Tuesday, August 7, 2012

Premenstrual Syndrome

Essentials of Diagnosis • Symptoms include mood symptoms (irritability, mood swings, depression, anxiety), physical symptoms (bloating, breast tenderness, insomnia, fatigue, hot flushes, appetite changes), and cognitive changes (confusion and poor concentration). • Symptoms must occur in the second half of the menstrual cycle (luteal phase). • There must be a symptom-free period of at least 7 days in the first half of the cycle. • Symptoms must occur in at least two consecutive cycles. • Symptoms must be severe enough to require medical advice or treatment. General Considerations Premenstrual syndrome (PMS) is a psychoneuroendocrine disorder with biologic, psychologic, and social parameters. It is both difficult to define adequately and quite controversial. One major difficulty in detailing whether PMS is a disease or a description of physiologic changes is its extraordinary prevalence. Up to 75% of women experience some recurrent PMS symptoms; 20–40% are mentally or physically incapacitated to some degree, and 5% experience severe distress. The highest incidence occurs in women in their late 20s to early 30s. PMS is rarely encountered in adolescents and resolves after menopause. Evidence suggests that women who have suffered with PMS and premenstrual dysphoric disorder are more likely to suffer from perimenopausal symptoms. The symptoms of PMS may include headache, breast tenderness, pelvic pain, bloating, and premenstrual tension. More severe symptoms include irritability, dysphoria, and mood lability. When these symptoms disrupt daily functioning, they are clustered under the name premenstrual dysphoric disorder (PMDD). Other symptoms commonly included in PMS are abdominal discomfort, clumsiness, lack of energy, sleep changes, and mood swings. Behavioral changes include social withdrawal, altered daily activities, marked change in appetite, increased crying, and changes in sexual desire. In all, more than 150 symptoms have been related to PMS. Thus the symptom complex of PMS has not been clearly defined. Pathogenesis The etiology of the symptom complex of PMS is not known, although several theories have been proposed, including estrogen–progesterone imbalance, excess aldosterone, hypoglycemia, hyperprolactinemia, and psychogenic factors. A hormonal imbalance previously was thought to be related to the clinical manifestations of PMS/PMDD, but in the most recent consensus, physiologic ovarian function is believed to be the trigger. This is supported by the efficacy of ovarian cyclicity suppression, either medically or surgically, in eliminating premenstrual complaints. Further research has shown that serotonin (5-hydroxytryptamine [5-HT]), a neurotransmitter, is important in the pathogenesis of PMS/PMDD. Both estrogen and progesterone have been shown to influence the activity of serotonin centrally. Many of the symptoms of other mood disorders resembling the features of PMS/PMDD have been associated with serotonergic dysfunction. Diagnosis No objective screening or diagnostic tests for PMS and PMDD are available; thus special attention must be paid to the patient's medical history. Certain medical conditions (eg, thyroid disease and anemia) with symptoms that can mimic those of PMS/PMDD must be ruled out. The patient is instructed to chart her symptoms for at least 2 symptomatic cycles. The classic criteria for PMS require that the patient have symptoms in the luteal phase and a symptom-free period of at least 7 days in the first half of the cycle for a minimum of 2 consecutive symptomatic cycles. To meet the criteria for PMDD, in addition to the criteria for PMS, she must have a chief complaint of at least 1 of the following: irritability, tension, dysphoria, or mood lability; and 5 of 11 of the following: depressed mood, anxiety, affective lability, irritability, decreased interest in daily activities, concentration difficulties, lack of energy, change in appetite or food cravings, sleep disturbances, feeling overwhelmed, or physical symptoms (eg, breast tenderness, bloating). Clinical Findings A careful history and physical examination are most important to exclude organic causes of PMS localized to the reproductive, urinary, or gastrointestinal tracts. Most patients readily describe their symptoms, but careful questioning may be needed with some patients who may be reluctant to do so. Although it is important not to lead a patient to exaggerate her concerns, it is equally important not to minimize them. Symptoms of PMS may be specific, well localized, and recurrent. They may be exacerbated by emotional stress. Migrainelike headaches may occur, often preceded by visual scotomas and vomiting. Symptomatology varies among patients but often is consistent in the same patient. A psychiatric history should be obtained, with special attention paid to a personal history of psychiatric problems or a family history of affective disorders. A mental status evaluation of affect, thinking, and behavior should be performed and recorded. A prospective diary correlating symptoms, daily activities, and menstrual flow can be useful to document changes and to encourage patient participation in her care. If underlying psychiatric illness is suspected, a psychiatric evaluation is indicated. The most common associated psychiatric illness is depression, which generally responds to antidepressant drugs and psychotherapy. Recall that psychiatric illnesses have premenstrual exacerbations, so medications should be altered accordingly. Treatment Treatment of PMS/PMDD depends on the severity of the symptoms. For some women, changes in eating habits—limiting caffeine, alcohol, tobacco, and chocolate intake, and eating small, frequent meals high in complex carbohydrates—may be sufficient. Decreasing sodium intake may alleviate edema. Stress management, cognitive behavioral therapy, and aerobic exercise have all been shown to improve symptoms. Low-risk pharmacologic interventions that may be effective include calcium carbonate (1000–1200 mg/d) for bloating, food cravings, and pain; magnesium (200–360 mg/day) for water retention; vitamin B6 (note that prolonged use of 200 mg/d may cause peripheral neurotoxicity) and vitamin E; nonsteroidal anti-inflammatory drugs (NSAIDs); spironolactone for cyclic edema; and bromocriptine for mastalgia. Herbal preparations have been proposed. St. John's wort has potential given its selective serotonin reuptake inhibitor (SSRI)-like effects but should be used with caution given its enzyme-inducing property on cytochrome P450. Chaste berry fruit (Vitex agnus-castus) 20 mg/day has been shown to be more effective than placebo and has minimal side effects but is not as effective as fluoxetine. For symptoms of severe PMS and PMDD, further pharmacologic intervention may be necessary. Psychotropic medications that are effective include SSRIs, desipramine, and L-tryptophan. SSRIs have minimal side effects and provide symptom improvement in more than 60% of patients studied. Treatment should be given 14 days prior to the onset of menstruation and continued through the end of the cycle. Anxiolytics such as alprazolam and buspirone also have been shown to be efficacious, but their side effects and potential for dependence must be seriously considered. Hormonal interventions have been shown to be effective. Use of gonadotropin-releasing hormone (GnRH) agonists leads to a temporary "medical menopause" and an improvement in symptoms. Their limitations lie in a hypoestrogenic state and a risk for osteoporosis, although "add-back" therapy with estrogen and progesterone may obviate these problems. Danazol may improve mastalgia. Finally, bilateral oophorectomy is a definitive surgical treatment option; again, estrogen replacement would be recommended. Use of oral contraceptives has been suggested because they suppress ovulation. However, studies have found little difference between women taking a low-dose birth control pill and women who do not take pills, and oral contraceptives currently are not recommended for treatment of PMS/PMDD.

Rupture of the Uterus


Essentials of Diagnosis
  • Fetal heart rate abnormalities.
  • Increased suprapubic pain and tenderness with labor.
  • Sudden cessation of uterine contractions with a "tearing" sensation.
  • Vaginal bleeding (or bloody urine).
  • Recession of the fetal presenting part.
General Considerations
Rupture of the pregnant uterus is a potential obstetric catastrophe and a major cause of maternal death. The incidence of uterine rupture is 0.8% for women with a prior low-transverse uterine scar and 4–8% for women with a prior classic scar. Complete rupture includes the entire thickness of the uterine wall and, in most cases, the overlying serosal peritoneum (broad ligament) (Fig 20–5). Occult or incomplete rupture is a term usually reserved for dehiscence of a uterine incision from previous surgery, in which the visceral peritoneum remains intact. Such defects usually are asymptomatic unless converted to complete rupture during the course of pregnancy or labor.
Risk factors
Risk factors for uterine rupture include history of hysterotomy (cesarean section, myomectomy, metroplasty, cornual resection), trauma (motor vehicle accident, rotational forceps, extension of a cervical laceration), uterine overdistention (hydramnios, multiple gestation, macrosomia), uterine anomalies, placenta percreta, and choriocarcinoma.
Ruptures usually occur during the course of labor. One notable exception is scars from a classic cesarean section (or hysterotomy), one-third of which rupture during the third trimester before term and before the onset of labor. Other causes of rupture without labor are placenta percreta, invasive mole, choriocarcinoma, and cornual pregnancy.
Complete ruptures can be classified as traumatic or spontaneous. Traumatic ruptures occur most commonly as a result of motor vehicle accidents, improper administration of an oxytocic agent, or an inept attempt at operative vaginal delivery. Breech extraction through an incompletely dilated cervix is the type of operative vaginal delivery most likely to produce uterine rupture. Other maneuvers that impose risk of rupture are internal podalic version and extraction, difficult forceps, destructive operations, and cephalic replacement to relieve shoulder dystocia. Neglected obstructed labor may be responsible for rupture of the uterus. Causes of obstructed labor include contracted pelvis, fetal macrosomia, brow or face presentation, hydrocephalus, or tumors involving the birth canal. The vast majority of uterine ruptures are associated with prior uterine surgery. Previous uterine surgery includes both classic and low cervical section, intramural or submucous myomectomy, resection of the uterine cornu, metroplasty, and trachelectomy. Other operative procedures that may have damaged the uterus are vigorous curettage, induced abortion, and manual removal of the placenta.
Clinical Findings
There are no reliable signs of impending uterine rupture that occurs before labor, although the sudden appearance of gross hematuria is suggestive.
Rupture may produce local pain and tenderness associated with increased uterine irritability and, in some cases, a small amount of vaginal bleeding. Premature labor may follow. As the extent of the rupture increases, more pain, more bleeding, and perhaps signs of hypovolemic shock will occur. Exsanguination prior to surgery is unlikely because of the reduced vascularity of scar tissue, but the placenta may be completely separated and the fetus extruded partially or completely into the abdominal cavity.
By far the most common clinical setting for rupture of the uterus is rupture of a low cervical scar; this almost always occurs during active labor. Clearly identifiable signs and symptoms may be lacking. However 78–90% of patients have FHR abnormalities as the first sign of rupture. Although it is possible that labor will progress to the vaginal birth of an unaffected infant, rupture may lacerate a uterine artery, producing exsanguination, or the fetus may be extruded into the abdominal cavity. If a defect is palpated in the lower uterine segment following vaginal delivery, laparotomy may be necessary to assess the damage. Laparotomy is mandatory if continuing hemorrhage is present. If such a defect is palpated in a stable patient who does not require exploration, a subsequent trial of labor is contraindicated.
Although much less common than FHR abnormalities, other findings of spontaneous rupture during labor are suprapubic pain and tenderness, cessation of uterine contractions, disappearance of fetal heart tones, recession of the presenting part, and vaginal hemorrhage—followed by the signs and symptoms of hypovolemic shock and hemoperitoneum. Ultrasound examination might confirm an abnormal fetal position or extension of the fetal extremities. Hemoperitoneum can sometimes be seen on ultrasound.
The clinical picture depends on the extent of rupture. Unfortunately, valuable time is often lost because the rupture was not diagnosed at the time of initial examination. Whenever a newly delivered patient exhibits persistent bleeding or shock, the uterus must be carefully reexamined for signs of a rupture that may have been difficult to palpate because of the soft, irregular tissue surfaces.
Whenever an operative delivery is performed—especially if the history includes events or problems that increase the likelihood of uterine rupture—the initial examination of the uterus and birth canal must be diligent. A dehiscence of the lower uterine segment contained only by a layer of visceral peritoneum is not an uncommon finding at time of repeat cesarean section.
Treatment
Treatment is dictated by clinical scenario and can range from simply repairing the defect and obtaining hemostasis to removing the entire uterus. If hysterectomy is deemed necessary, either total hysterectomy or the subtotal operation can be performed, depending on the site of rupture and the patient's condition. The most difficult cases are lateral ruptures involving the lower uterine segment and a uterine artery with hemorrhage and hematoma formation obscuring the operative field. Care must be taken to avoid ureteral damage by blind suturing at the base of the broad ligament. If there is a question of ureteral occlusion by a suture, it is best to perform cystotomy to observe the bilateral appearance of an intravenously injected dye such as indigo carmine. If doubt still exists, a retrograde ureteral catheter can be passed upward through the cystotomy wound.
If childbearing is important and the risks—both short and long term—are acceptable to the patient, rupture repair can be attempted. Many ruptures can be repaired. Successful pregnancies have been reported following uterine repair; however, the risk of rupture in a subsequent pregnancy is at least as high as the risk with a prior classic cesarean section. Occult ruptures of the lower uterine segment encountered at repeat section can be treated by freshening the wound edges and secondary repair, but the newly repaired incision is at increased risk for rupture, and a subsequent trial of labor is contraindicated.
Prevention
Most causes of uterine rupture can be avoided by carefully selecting patients for trial of labor. Thorough and well-documented informed consent that includes mention of fetal or maternal death is needed. The ideal candidate will have a single prior low-transverse cesarean for a nonrepetitive indication (eg, breech), will have a prior vaginal delivery, will present in active labor, and will not require augmentation during labor. The further the characteristics diverge from those of this ideal patient, the greater the chance of a failed trial of labor and complications including uterine rupture. Continuous FHR monitoring by fetal scalp electrode as soon as feasible is the best means of detecting evolving rupture during labor. Two-layer closure of the uterine incision and increasing interval between pregnancies appears to decrease the risk of subsequent rupture of the low-transverse scar.
Complications
The complications of ruptured uterus are hemorrhage, shock, postoperative infection, bladder or ureteral damage, thrombophlebitis, amniotic fluid embolus, DIC, pituitary failure, and death.
Prognosis
The maternal mortality rate is 4.2%. The perinatal mortality rate is approximately 46%


Umbilical Cord Prolapse


Umbilical cord prolapse is defined as descent of the umbilical cord into the lower uterine segment, where it may lie adjacent to the presenting part (occult cord prolapse) or below the presenting part (overt cord prolapse) . In occult prolapse, the umbilical cord cannot be palpated during pelvic examination, whereas in funic presentation, which is characterized by prolapse of the umbilical cord below the level of the presenting part before the rupture of membranes occurs, the cord often can be easily palpated through the membranes. Overt cord prolapse is associated with rupture of the membranes and displacement of the umbilical cord into the vagina, often through the introitus.
Prolapse of the umbilical cord to a level at or below the presenting part exposes the cord to intermittent compression between the presenting part and the pelvic inlet, cervix, or vaginal canal. Compression of the umbilical cord compromises fetal circulation and, depending on the duration and intensity of compression, may lead to fetal hypoxia, brain damage, and death. In overt cord prolapse, exposure of the umbilical cord to air causes irritation and cooling of the cord, resulting in further vasospasm of the cord vessels.
The incidence of overt umbilical cord prolapse in cephalic presentations is 0.5%, frank breech 0.5%, complete breech 5%, footling breech 15%, and transverse lie 20%. The incidence of occult prolapse is unknown because it can be detected only by fetal heart rate changes characteristic of umbilical cord compression. However, some degree of occult prolapse appears to be common, given that as many as 50% of monitored labors demonstrate fetal heart rate changes compatible with umbilical cord compression. In most cases, the compression is transient and can be rectified simply by changing the patient's position.
Whether occult or overt, umbilical cord prolapse is associated with significant rates of perinatal morbidity and mortality because of intermittent compression of blood flow and resultant fetal hypoxia. The perinatal mortality rate associated with all cases of overt umbilical cord prolapse approaches 20%. Prematurity, itself a contributor to the incidence of umbilical cord prolapse, accounts for a considerable portion of this perinatal loss.
Causes
Any obstetric condition that predisposes to poor application of the fetal presenting part to the cervix can result in prolapse of the umbilical cord. Cord prolapse is associated with prematurity (< 34 weeks' gestation), abnormal presentations (breech, brow, compound, face, transverse), occiput posterior positions of the head, pelvic tumors, multiparity, placenta previa, low-lying placenta, and cephalopelvic disproportion. In addition, cord prolapse is possible with hydramnios, multiple gestation, or premature rupture of the membranes occurring before engagement of the presenting part. A recent study revealed that obstetric intervention contributes to nearly half of cases of umbilical cord prolapse. Examples cited include amniotomy, scalp electrode application, intrauterine pressure catheter insertion, attempted external cephalic version, and expectant management of preterm premature rupture of membranes.
Clinical Findings
Overt Cord Prolapse
Overt cord prolapse can be diagnosed simply by visualizing the cord protruding from the introitus or by palpating loops of cord in the vaginal canal.
Funic Presentation
The diagnosis of funic presentation is made by pelvic examination if loops of cord are palpated through the membranes. Antepartum detection of funic presentation is discussed below.
Occult Prolapse
Occult prolapse is rarely palpated during pelvic examination. This condition can be inferred only if fetal heart rate changes (variable decelerations, bradycardia, or both) associated with intermittent compression of the umbilical cord are detected during monitoring.
Fetus
The fetus in good condition whose well-being is jeopardized by umbilical cord compression may exhibit violent activity readily apparent to the patient and the obstetrician. Variable fetal heart rate decelerations will occur during uterine contractions, with prompt return of the heart rate to normal as each contraction subsides. If cord compression is complete and prolonged, fetal bradycardia occurs. Persistent, severe, variable decelerations and bradycardia lead to development of hypoxia, metabolic acidosis, and eventual damage or death. As the fetal status deteriorates, activity lessens and eventually ceases. Meconium staining of the amniotic fluid may be noted at the time of membrane rupture.
Complications
Maternal
Cesarean section is a major operative procedure with known anesthetic, hemorrhagic, and operative complications. These risks must be weighed against the real risk to the fetus of continued hypoxia if labor were to continue.
Maternal risks encountered at vaginal delivery include laceration of the cervix, vagina, or perineum resulting from a hastily performed delivery.
Neonatal
The neonate at delivery may be hypoxic, acidotic, or moribund. A pediatric team should be present to effect immediate resuscitation of the newborn.
Prevention
Patients at risk for umbilical cord prolapse should be treated as high-risk patients. Patients with malpresentations or poorly applied cephalic presentations should be considered for ultrasonographic examination at the onset of labor to determine fetal lie and cord position within the uterine cavity. Because most prolapses occur during labor as the cervix dilates, patients at risk for cord prolapse should be continuously monitored to detect abnormalities of the fetal heart rate. Artificial rupture of membranes should be avoided until the presenting part is well applied to the cervix. At the time of spontaneous membrane rupture, a prompt, careful pelvic examination should be performed to rule out cord prolapse. Should amniotomy be required and the presenting part remains unengaged, careful needling of the membranes and slow release of the amniotic fluid can be performed until the presenting part settles against the cervix.
Management
Overt Cord Prolapse
The diagnosis of overt cord prolapse demands immediate action to preserve the life of the fetus. An immediate pelvic examination should be performed to determine cervical effacement and dilatation, station of the presenting part, and strength and frequency of pulsations within the cord vessels. If the fetus is viable, the patient should be placed in the knee–chest position, and the examiner should apply continuous upward pressure against the presenting part to lift and maintain the fetus away from the prolapsed cord until preparations for cesarean delivery are complete. Alternatively, 400–700 mL of saline can be instilled into the bladder in order to elevate the presenting part. Oxygen should be given to the mother until the anesthesiologist is prepared to administer a rapid-acting inhalation anesthetic for delivery. Successful reduction of the prolapsed umbilical cord has been described, but such an attempt may worsen fetal heart rate changes and should not delay preparation for cesarean delivery. Abdominal delivery should be accomplished as rapidly as possible through a generous midline abdominal incision, and a pediatric team should be on standby in the event immediate resuscitation of the newborn is necessary.
Occult Cord Prolapse
If cord compression patterns (variable decelerations) of the fetal heart rate are recognized during labor, an immediate pelvic examination should be performed to rule out overt cord prolapse. If occult cord prolapse is suspected, the patient should be placed in the lateral Sims or Trendelenburg position in an attempt to alleviate cord compression. If the fetal heart rate returns to normal, labor can be allowed to continue, provided no further fetal insult occurs. Oxygen should be administered to the mother, and the fetal heart rate should be continuously monitored electronically. Amnioinfusion can be performed via an intrauterine pressure catheter in order to instill fluid within the uterine cavity and possibly decrease the incidence of variable decelerations. If the cord compression pattern persists or recurs to the point of fetal jeopardy (moderate to severe variable decelerations or bradycardia), a rapid cesarean section should be accomplished.
Funic Presentation
The patient at term with funic presentation should be delivered by cesarean section prior to membrane rupture. However, there is no consensus on management if the fetus is premature. The most conservative approach is to hospitalize the patient on bed rest in the Sims or Trendelenburg position in an attempt to reposition the cord within the uterine cavity. Serial ultrasonographic examinations should be performed to ascertain cord position, presentation, and gestational age.
Route of Delivery
Vaginal delivery can be successfully accomplished in cases of overt or occult cord prolapse if, at the time of prolapse, the cervix is fully dilated, cephalopelvic disproportion is not anticipated, and an experienced physician determines that delivery is imminent. Internal podalic version, midforceps rotation, or any other operative technique is generally more hazardous to mother and fetus in this situation than is a judiciously performed cesarean delivery. Cesarean delivery is the preferred route of delivery in most cases. Vaginal delivery is the route of choice for the previable or dead fetus.
Prognosis
Maternal
Maternal complications include those related to anesthesia, blood loss, and infection following cesarean section or operative vaginal delivery. Maternal recovery is generally complete.
Neonatal
Although the prognosis for intrapartum cord prolapse is greatly improved, fetal mortality and morbidity rates still can be high, depending on the degree and duration of umbilical cord compression occurring before the diagnosis is made and neonatal resuscitation is started. If the diagnosis is made early and the duration of complete cord occlusion is less than 5 minutes, the prognosis is good. Gestational age and trauma at delivery also affect the final neonatal outcome. If complete cord occlusion has occurred for longer than 5 minutes or if intermittent partial cord occlusion has occurred over a prolonged period of time, fetal damage or death may occur.


Thursday, August 2, 2012

Abruptio Placentae


Premature Separation of the Placenta (Abruptio Placentae, Marginal Sinus Bleed
Essentials of Diagnosis
  • Unremitting abdominal (uterine) or back pain.
  • Irritable, tender, and often hypertonic uterus.
  • Visible or concealed hemorrhage.
  • Evidence of fetal distress may or may not be present, depending on the severity of the process.
General Considerations
Premature separation of the placenta is defined as separation from the site of uterine implantation before delivery of the fetus
The term premature separation of the normally implanted placenta is most descriptive because it differentiates the placenta that separates prematurely but that is implanted some distance beyond the cervical internal os from one that is implanted over the cervical internal os—that is, placenta previa. This is cumbersome, however, and hence a shorter term abruptio placenta, or placental abruption, has been used. The Latin abruptio placentae, which means "rending asunder of the placenta," denotes a sudden accident, a clinical characteristic of most cases of this complication.
Two principal forms of premature separation of the placenta can be recognized, depending on whether the resulting hemorrhage is external or concealed
Concealed form
Less often, the blood does not escape externally but is retained between the detached placenta and the uterus, leading to concealed hemorrhage
Detachment of the placenta may be complete, and the complications often are severe. Approximately 10% of abruptions are associated with clinically significant coagulopathies (disseminated intravascular coagulation [DIC]), but 40% of those severe enough to cause fetal death are associated with coagulopathy
External form
Some of the bleeding of placental abruption usually insinuates itself between the membranes and uterus, and then escapes through the cervix, causing external hemorrhage
Placental detachment is more likely to be incomplete, and the complications are fewer and less severe. Occasionally, the placental detachment involves only the margin or placental rim. Here, the most important complication is the possibility of premature labor.
Etiology
The hypertensive states of pregnancy are associated with 2.5–17.9% incidence of placental separation
Other predisposing factors include advanced maternal age, multiparity, uterine distention (e.g., multiple gestation, hydramnios), vascular disease (e.g., diabetes mellitus, systemic lupus erythematosus), thrombophilias, uterine anomalies or tumors (e.g., leiomyoma), cigarette smoking, alcohol consumption (> 14 drinks per week), cocaine use, and possibly maternal type O blood.
Risk Factors for Placental Abruption
Risk Factor
Increased age and parity
Preeclampsia
Chronic hypertension
Preterm ruptured membranes
Multifetal gestation
Hydramnios
Cigarette smoking
Thrombophilias
Cocaine use
Prior abruption
Uterine leiomyoma

Pathophysiology & Pathology
Several mechanisms are thought to be important in the pathophysiology of premature placental separation. One mechanism is local vascular injury that results in vascular rupture into the decidua basalis, bleeding, and hematoma formation. The hematoma shears off adjacent denuded vessels, producing further bleeding and enlargement of the area of separation.
Another mechanism is initiated by an abrupt rise in uterine venous pressure transmitted to the intervillous space. This results in engorgement of the venous bed and separation of all or a portion of the placenta.
Conditions predisposing to vascular injury and known to be associated with an increased incidence of placental separation are preeclampsia–eclampsia, chronic hypertension, diabetes mellitus, chronic renal disease, cigarette smoking, and cocaine use.
Retained or concealed hemorrhage is likely when:
1.      There is an effusion of blood behind the placenta but its margins still remain adherent.
2.      The placenta is completely separated yet the membranes retain their attachment to the uterine wall.
3.      Blood gains access to the amnionic cavity after breaking through the membranes.
4.      The fetal head is so closely applied to the lower uterine segment that the blood cannot make its way past it.
Clinical Findings
Signs and Symptoms in patients with abruptio placentae
Sign or Symptom
Vaginal bleeding
Uterine tenderness or back pain
Fetal distress
Preterm labor a
 
High-frequency contractions
Hypertonus
Dead fetus

Differential Diagnosis
With severe placental abruption, the diagnosis generally is obvious. Milder and more common forms of abruption are difficult to recognize with certainty, and the diagnosis is often made by exclusion. Unfortunately, neither laboratory tests nor diagnostic methods are available to detect lesser degrees of placental separation accurately. Therefore, with vaginal bleeding complicating a viable pregnancy, it often becomes necessary to rule out placenta previa and other causes of bleeding by clinical inspection and ultrasound evaluation. It has long been taught, perhaps with some justification, that painful uterine bleeding means placental abruption, whereas painless uterine bleeding is indicative of placenta previa. Unfortunately, the differential diagnosis is not that simple. Labor accompanying placenta previa may cause pain suggestive of placental abruption. On the other hand, abruption may mimic normal labor, or it may cause no pain at all. The latter is more likely with a posteriorly implanted placenta. At times, the cause of the vaginal bleeding remains obscure even after delivery.
Management
Expectant Management in Preterm Pregnancy
Delaying delivery may prove beneficial when the fetus is immature, but it is exceptional, not rule. This management pathway should be attempted only with careful observation of the patient and a clear clinical picture. In general, expectant management may be appropriate when the mother is stable, the fetus is immature, and the fetal heart tracing is reassuring. The patient should be observed in the labor and delivery suite for 24–48 hours to ensure that further placental separation is not occurring. Continuous fetal and uterine monitoring should be maintained. Changes in fetal status may be the earliest indication of an expanding abruption.
Emergency Measures
Most cases of placental abruption are diagnosed as an acute event (upon presentation to labor and delivery or during the intrapartum period), making immediate intervention necessary. If the patient exhibits clinical findings that become progressively more severe or if a major placental separation is suspected as manifested by hemorrhage, uterine spasm, or fetal distress, an acute emergency exists.
Blood should be drawn for laboratory studies and at least 4 units of PRBCs typed and crossed. Two large-bore intravenous catheters should be placed and crystalloid administered.
Otherwise delivery should be considered either with caesarian section or vaginal delivery as patient’s condition and pregnancy allows.
 Vaginal Delivery
An attempt at vaginal delivery is indicated if the degree of separation appears to be limited and if the continuous FHR tracing is reassuring. When placental separation is extensive but the fetus is dead or of dubious viability, vaginal delivery is indicated. The exception to vaginal delivery is the patient in whom hemorrhage is uncontrollable and operative delivery is necessary to save the life of the fetus or mother.
Induction of labor with an oxytocin infusion should be instituted if active labor does not begin shortly after amniotomy. In practice, augmentation often is not needed because usually the uterus is already excessively irritable. If the uterus is extremely spastic, uterine contractions cannot be clearly identified unless an internal monitor is used, and the progress of labor must be judged by observing cervical dilatation. Pudendal block anesthesia is recommended. Conduction anesthesia is to be avoided in the face of significant hemorrhage because profound, persistent hypotension may result. However, in the volume-repleted patient in early labor, a preemptive epidural should be considered because rapid deterioration of maternal or fetal status can occur as labor progresses.
Cesarean Section
The indications for cesarean section are both fetal and maternal. Abdominal delivery should be selected whenever delivery is not imminent for a fetus with a reasonable chance of survival who exhibits persistent evidence of distress. Cesarean section also is indicated if the fetus is in good condition but the situation is not favorable for rapid delivery in the face of progressive or severe placental separation. This includes most nulliparous patients with less than 3–4 cm of cervical dilatation. Maternal indications for cesarean section are uncontrollable hemorrhage from a contracting uterus, rapidly expanding uterus with concealed hemorrhage (with or without a live fetus) when delivery is not imminent, uterine apoplexy as manifested by hemorrhage with secondary relaxation of a previously spastic uterus, or refractory uterus with delivery necessary (20%).
Complications
Disseminated Intravascular Coagulation
Placental abruption can lead to initiation of the coagulation cascade by release of tissue thromboplastin into the maternal circulation. Consumption of coagulation factors and platelets is followed by coagulopathic hemorrhage. A cycle ensues as further bleeding worsens the depletion of coagulation factors. Continuous monitoring for evidence of a clotting deficiency is mandatory from the time the diagnosis of placental abruption is considered well into the postpartum period. Treatment will depend not only on the demonstration of hematologic deficiencies but also on the amount of active bleeding and the anticipated route of delivery.
Reference
Tenth edition of Current Diagnosis & Treatment Obstetrics & Gynecology.
Twenty second edition Williams Obstetrics 










Placenta Previa


Essentials of Diagnosis
  • Spotting during first and second trimesters.
  • Sudden, painless, profuse bleeding in third trimester.
  • Initial cramping in 10% of cases.
General Considerations
In placenta previa, the placenta is implanted in the lower uterine segment within the zone of effacement and dilatation of the cervix, constituting an obstruction to descent of the presenting part
Etiology
The incidence of placenta previa is increased by multiparity, advancing age, and previous cesarean delivery. Thus, possible etiologic factors include scarred or poorly vascularized endometrium in the corpus, a large placenta, and abnormal forms of placentation such as succenturiate lobe. The incidence of placenta previa is slightly higher in multiple gestation. A cesarean section scar triples the incidence of placenta previa. Another contributory factor is an increased average surface area of a placenta implanted in the lower uterine segment, possibly because these tissues are less well suited for nidation.
Bleeding in placenta previa may be due to any of the following causes: (1) mechanical separation of the placenta from its implantation site, either during the formation of the lower uterine segment or during effacement and dilatation of the cervix in labor, or as a result of intravaginal manipulation; (2) placentitis; or (3) rupture of poorly supported venous lakes in the decidua basalis that have become engorged with venous blood.
Classification
1. Complete placenta previa: The placenta completely covers the internal cervical os.
2. Marginal placenta previa: The placenta is implanted at the margin of the internal cervical os, within 2 cm. If the placenta is seen to be more than 2 cm from the internal os, the rate of antepartum or intrapartum hemorrhage is not increased.
Diagnosis
Every patient suspected of placenta previa should be hospitalized, and cross-matched blood should be at hand. To avoid provoking hemorrhage, both vaginal and rectal examination should not be performed.
Symptoms and Signs
Painless hemorrhage is the cardinal sign of placenta previa. Although spotting may occur during the first and second trimesters of pregnancy, the first episode of hemorrhage usually begins after the 28th week and is characteristically described as sudden, painless, and profuse. With the initial bleeding episode, clothing or bedding may be soaked by an impressive amount of bright red, clotted blood, but the blood loss usually is not extensive, seldom produces shock, and almost never is fatal. In approximately 10% of cases there is some initial pain, probably because of coexisting placental separation and localized uterine contractions. Spontaneous labor can be expected over the next few days in 25% of patients. In a small minority of cases, bleeding is less dramatic or does not begin until after spontaneous rupture of the membranes or the onset of labor. A few nulliparous patients even reach term without bleeding, possibly because the placenta has been protected by an uneffaced cervix.
The uterus usually is soft, relaxed, and nontender. A high presenting part cannot be pressed into the pelvic inlet. The infant will present in an oblique or transverse lie in approximately 15% of cases. FHR abnormalities are unlikely unless there are complications such as hypovolemic shock, placental separation, or a cord accident.
Ultrasonography
 Bedside transabdominal ultrasonography can definitively identify 95% of placenta previas. Transvaginal or transperineal studies can make the diagnosis in virtually every case. This approach is particularly helpful with the posterior placenta previa.


During the middle of the second trimester, the placenta is observed by ultrasound to cover the internal cervical os in approximately 30% of cases. With development of the lower uterine segment, almost all of these low implantations will be carried to a higher station. An early ultrasonic diagnosis of placenta previa requires the confirmation of an additional study before definitive action is taken.
Differential Diagnosis
Placental causes of bleeding other than placenta previa include partial premature separation of the normally implanted placenta or circumvallate placenta.
Treatment
The treatment depends on the amount of uterine bleeding; the duration of pregnancy and viability of the fetus; the degree of placenta previa; the presentation, position, and station of the fetus; the gravidity and parity of the patient; the status of the cervix; and whether or not labor has begun. The patient must be admitted to the hospital to establish the diagnosis and ideally should remain in the hospital once the diagnosis is made. Blood should be readily available for transfusion.
Expectant Therapy
The initial hemorrhage of placenta previa may occur before pulmonary maturity is established. In such cases, fetal survival can often be enhanced by expectant therapy. Early in pregnancy, transfusions to replace blood loss and the use of tocolytic agents to prevent premature labor are indicated to prolong pregnancy to at least 32–34 weeks. After 34 weeks, the benefits of further maturation must be weighed against the risk of major hemorrhage. The possibility that repeated small hemorrhages may be accompanied by intrauterine growth retardation also must be considered. Approximately 75% of cases of placenta previa are now delivered between 36 and 40 weeks.
In selecting the optimum time for delivery, tests of fetal lung maturation, including assessment of amniotic fluid surfactants and ultrasonic growth measurements, are valuable adjuvants.
If the patient is between 24 and 34 weeks' gestational age, a single course of betamethasone (2 doses of 12 mg intramuscularly separated by 24 hours) or dexamethasone (4 doses of 6 mg intravenously or intramuscularly separated by 12 hours) should be given to promote fetal lung maturity. Repeat courses of steroids are not necessary and usually are considered only for patients who initially present and receive treatment with steroids at less than 24 weeks.
Because of the costs of hospitalization, patients with a presumptive diagnosis of placenta previa are sometimes sent home on strict bed rest after their condition has become stable under ideal, controlled circumstances. Such a policy is always a calculated risk in view of the unpredictability of further hemorrhage, but the practice has been studied and is an acceptable alternative.
Delivery
Cesarean Section
Cesarean section is the delivery method of choice with placenta previa. Cesarean section has proved to be the most important factor in lowering maternal and perinatal mortality rates (more so than blood transfusion or better neonatal care).
If possible, hypovolemic shock should be corrected by administration of intravenous fluids and blood before the operation is started. Not only will the mother be better protected, but an at-risk fetus will recover more quickly in utero than if born while the mother is still in shock.
The choice of anesthesia depends on current and anticipated blood loss. A combination of rapid induction, endotracheal intubation, succinylcholine, and nitrous oxide is a suitable method for proceeding in the presence of active bleeding.
The choice of operative technique is of importance because of the placental location and the development of the lower uterine segment. If the incision passes through the site of placental implantation, there is a strong possibility that the fetus will lose a significant amount of blood—even enough to require subsequent transfusion. With posterior implantation of the placenta, a low-transverse incision may be best if the lower uterine segment is well developed. Otherwise, a classic incision may be required to secure sufficient room and to avoid incision through the placenta. Preparations should be made for care and resuscitation of the infant if it becomes necessary. In addition, the possibility of blood loss should be monitored in the newborn if the placenta has been incised.
In a small percentage of cases, hemostasis in the placental bed is unsatisfactory because of the poor contractility of the lower uterine segment. Mattress sutures or packing may be required in addition to the usual oxytocin, prostaglandins, and methylergonovine. If placenta previa accreta is found, hemostasis may necessitate a total hysterectomy. Puerperal infection and anemia are the most likely postoperative complications.
Vaginal Delivery
Vaginal delivery usually is reserved for patients with a marginal implantation and a cephalic presentation. If vaginal delivery is elected, the membranes should be artificially ruptured prior to any attempt to stimulate labor (oxytocin given before amniotomy likely will cause further bleeding). Tamponade of the presenting part against the placental edge usually reduces bleeding as labor progresses.
Because of the possibility of fetal hypoxemia due to either placental separation or a cord accident (as a result of either prolapse or compression of low insertion of the cord by the descending presenting part), continuous fetal monitoring must be used. If FHR abnormalities develop, a rapid cesarean section should be performed unless vaginal delivery is imminent.
Deliver the patient in the easiest and most expeditious manner as soon as the cervix is fully dilated and the presenting part is on the perineum. For this purpose, a vacuum extractor is particularly valuable because it expedites delivery without risking rupture of the lower uterine segment.
Complications
Maternal
Maternal hemorrhage, shock, and death may follow severe antepartum bleeding resulting from placenta previa. Death may occur as a result of intrapartum and postpartum bleeding, operative trauma, infection, or embolism.
Premature separation of a portion of a placenta previa occurs in virtually every case and causes excessive external bleeding without pain; however, complete or wide separation of the placenta before full dilatation of the cervix is uncommon.
Placenta previa accreta is a serious abnormality in which the sparse endometrium and the myometrium of the lower uterine segment are penetrated by the trophoblast in a manner similar to placenta accreta higher in the uterus. In patients with 1 prior cesarean section, the rate of accreta in the presence of previa is 20–25% and rises to 50% with 2 or more prior cesarean sections.
Fetal
Prematurity (gestational age < 36 weeks) accounts for 60% of perinatal deaths due to placenta previa. The fetus may die as a result of decreased oxygen delivery intrapartum or birth injury. Fetal hemorrhage due to tearing of the placenta occurs with vaginal manipulation and especially upon entry into the uterine cavity as cesarean section is done for placenta previa. About half of these cesarean babies lose some blood. Fetal blood loss is directly proportional to the time that elapses between lacerating the cotyledon and clamping the cord.
Prognosis
Maternal
With rapid recourse to cesarean section, use of banked blood, and expertly administered anesthesia, the overall maternal mortality has fallen to less than 1 in 1000.
Fetal
The perinatal mortality rate associated with placenta previa has declined to approximately 1%. Although premature labor, placental separation, cord accidents, and uncontrollable hemorrhage cannot be avoided, the mortality rate can be greatly reduced if ideal obstetric and newborn care is given.

Wednesday, August 1, 2012

Breech presentation

Breech presentation, which complicates 3–4% of all pregnancies, occurs when the fetal pelvis or lower extremities engage the maternal pelvic inlet. Three types of breech are distinguished, according to fetal attitude (Fig 21–1). In frank breech, the hips are flexed with extended knees bilaterally. In complete breech, both hips and knees are flexed. In footling breech, 1 (single footling breech) or both (double footling breech) legs are extended below the level of the buttocks.
In singleton breech presentations in which the infant weighs less than 2500 g, 40% are frank breech, 10% complete breech, and 50% footling breech. With birth weights of more than 2500 g, 65% are frank breech
, 10% complete breech, and 25% footling breech.
Fetal position in breech presentation is determined by using the fetal sacrum as the point of reference to the maternal pelvis. This is true for frank, complete, and footling breeches. Eight possible positions are recognized: sacrum anterior (SA), sacrum posterior (SP), left sacrum transverse (LST), right sacrum transverse (RST), left sacrum anterior (LSA), left sacrum posterior (LSP), right sacrum anterior (RSA), and right sacrum posterior (RSP). The station of the breech presenting part is the location of the fetal sacrum with regard to the maternal ischial spines.

Causes
Before 28 weeks, the fetus is small enough in relation to intrauterine volume to rotate from cephalic to breech presentation and back again with relative ease. As gestational age and fetal weight increase, the relative decrease in intrauterine volume makes such changes more difficult. In most cases, the fetus spontaneously assumes the cephalic presentation to better accommodate the bulkier breech pole in the roomier fundal portion of the uterus.
Breech presentation occurs when spontaneous version to cephalic presentation is prevented as term approaches or if labor and delivery occur prematurely before cephalic version has taken place. Some causes include oligohydramnios, hydramnios, and uterine anomalies such as bicornuate or septate uterus, pelvic tumors obstructing the birth canal, abnormal placentation, advanced multiparity, and a contracted maternal pelvis.
In multiple gestations, each fetus may prevent the other from turning, with a 25% incidence of breech in the first twin, nearly 50% for the second twin, and higher percentages with additional fetuses. Additionally, 6% of breech presentations are found to have congenital malformations, which include congenital hip dislocation, hydrocephalus, anencephalus, familial dysautonomia, spina bifida, meningomyelocele, and chromosomal trisomies 13, 18, and 21. Thus, those conditions that alter fetal muscular tone and mobility increase the likelihood of breech presentation.
Diagnosis
Palpation and Ballottement
Performance of Leopold's maneuvers and ballottement of the uterus may confirm breech presentation. The softer, more ill-defined breech may be felt in the lower uterine segment above the pelvic inlet. Diagnostic error is common, however, if these maneuvers alone are used to determine presentation.
Pelvic Examination
During vaginal examination, the round, firm, smooth head in cephalic presentation can easily be distinguished from the soft, irregular breech presentation if the presenting part is palpable. However, if no presenting part is discernible, further studies are necessary (ie, ultrasound).
Radiographic Studies
X-ray studies will differentiate breech from cephalic presentations and help determine the type of breech by locating the position of the lower extremities. X-ray studies can reveal multiple gestation and skeletal defects. Fetal attitude may be seen, but fetal size cannot readily be determined by x-ray film. Because of the risks of radiation exposure to the fetus with this technique, ultrasonography is now used instead of radiography to determine fetal presentation or malformations.
Ultrasound
Ultrasonographic scanning by an experienced examiner will document fetal presentation, attitude, and size; multiple gestation; location of the placenta; and amniotic fluid volume. Ultrasound also will reveal skeletal and soft-tissue malformations of the fetus.
Management
Antepartum Management
Following confirmation of breech presentation, the mother must be closely followed to evaluate for spontaneous version to cephalic presentation. If breech presentation persists beyond 36 weeks, external cephalic version should be considered (see below).
In women considering a vaginal breech delivery, radiographic pelvimetry using x-ray, computed tomography, or magnetic resonance imaging should be performed to rule out women with a borderline or contracted pelvis. Attempts at vaginal delivery with an inadequate pelvis are associated with a high rate of difficulty and significant trauma to mother and fetus. Difficult vaginal delivery may still occur in women with adequate pelvic measurements.
Management during Labor
Examination
Patients with singleton breech presentations are admitted to the hospital with the onset of labor or when spontaneous rupture of membranes occurs because of the increased risk of umbilical cord complications. Upon admission, a repeat ultrasound is obtained to confirm the type of breech presentation and to ascertain head flexion. The fetus is again screened for lethal congenital malformations, such as anencephaly, which would preclude cesarean delivery for fetal indications. A thorough history is taken, and a physical examination is performed to evaluate the status of mother and fetus. Based on these findings, a decision must be made regarding the route of delivery (see below).
Electronic Fetal Monitoring
Continuous electronic fetal heart rate monitoring is essential during labor. If a fetal electrocardiographic electrode is needed, care should be taken to avoid injury to the fetal anus, perineum, and genitalia when attaching the electrode to the breech presenting part. An intrauterine pressure catheter can be used to assess the frequency, strength, and duration of uterine contractions. With the catheter in place, fetal distress or dysfunctional labor can easily be identified and the decision to proceed with a cesarean section made expeditiously to optimize fetal outcome.
Oxytocin
The use of oxytocin in the management of breech labor is controversial. Although some obstetricians condemn its use, others use oxytocin with benefit and without complications. Generally, oxytocin should be administered only if uterine contractions are insufficient to sustain normal progress in labor. Continuous fetal and uterine monitoring should be used whenever oxytocin is administered.
Delivery
The decision regarding route of delivery must be made carefully on an individual basis. Criteria for vaginal or cesarean delivery are outlined in Table.
Criteria for Vaginal or Cesarean Delivery in Breech Presentation.
Vaginal Delivery
Cesarean Delivery
Frank breech presentation 
Estimated fetal weight of 3500 g or more, or less than 1500 g. 
Gestational age of 34 weeks or more. 
Contracted or borderline maternal pelvic measurements. 
Estimated fetal weight of 2000–3500 g.
Flexed fetal head.
Adequate maternal pelvis as determined by x–ray pelvimetry (pelvic inlet with transverse diameter of 11.5 cm and anteroposterior diameter of 10.5 cm; midpelvis with transverse diameter of 10 cm and anteroposterior diameter of 11.5 cm).
No maternal or fetal indications for cesarean section.
Previable fetus (gestational age < 25 weeks and weight < 700 g).
Documented lethal fetal congenital anomalies.
Presentation of mother in advanced labor with no fetal or maternal distress; even if cesarean delivery was originally planned (a carefully performed, controlled vaginal delivery is safer in such cases than is a hastily executed cesarean section).
Deflexed or hyperextended fetal head.
Prolonged rupture of membranes.
Unengaged presenting part.
Dysfunctional labor.
Elderly primigravida.
Mother with infertility problems or poor obstetric history.
Premature fetus (gestational age of 25–34 weeks).
Most cases of complete or footling breech over 25 weeks' gestation without detectable lethal congenital malformations (to prevent umbilical cord prolapse).
Fetus with variable heart rate decelerations on electronic monitoring
Footling presentation

Cesarean Delivery
The type of incision chosen is extremely important. If the lower uterine segment is well developed, as is usually the case in women at term in labor, a transverse "lower segment" incision is adequate for easy delivery. In premature gestations, in an unlabored uterus, or in many cases of malpresentation, the lower uterine segment may be quite narrow, and a low vertical incision is almost always required for atraumatic delivery.
Vaginal Delivery
Obstetricians who contemplate performing a vaginal breech delivery should be experienced in the maneuver and should be assisted by 3 physicians: (1) an experienced obstetrician who will assist with delivery; (2) a pediatrician capable of providing total resuscitation of the newborn; and (3) an anesthesiologist, to ensure that the mother is comfortable and cooperative during labor and delivery. The type of anesthesia required depends on the type of breech delivery. Multiparous women undergoing spontaneous breech delivery may require no anesthesia or only intravenous analgesia for pain relief during labor and a pudendal anesthetic during delivery. Epidural anesthesia may also be administered during labor or in anticipation of partial breech extraction, including application of Piper forceps to the aftercoming head. In emergency circumstances, complete relaxation of the perineum and uterus is essential for a successful outcome. This is accomplished by immediate induction of inhalation anesthesia or by administration of intravenous nitroglycerin.
Spontaneous Vaginal Delivery
During spontaneous delivery of an infant in the frank breech position, delivery occurs without assistance, and no obstetric maneuvers are applied to the body. The fetus negotiates the maternal pelvis as outlined below, while the operator simply supports the body as it delivers.
Engagement occurs when the bitrochanteric diameter of the fetus has passed the plane of the pelvic inlet. As the fetus descends into the pelvis (Fig 21–2), the buttocks reach the levator ani muscles of the maternal pelvis. At this point, internal rotation occurs, whereby the anterior hip rotates beneath the pubic symphysis, resulting in a sacrum transverse position. The bitrochanteric diameter of the fetal pelvis is now in an anteroposterior position within the maternal pelvis. The breech then presents at the pelvic outlet and, upon emerging, rotates from sacrum transverse to sacrum anterior. Crowning occurs when the bitrochanteric diameter passes under the pubic symphysis. As this occurs, the shoulders enter the pelvic inlet with the bisacromial diameter in the transverse position. As descent occurs, the bisacromial diameter rotates to an oblique or anteroposterior diameter, until the anterior shoulder rests beneath the pubic symphysis. Delivery of the anterior shoulder occurs as it slips beneath the pubic symphysis. Upward flexion of the body allows for easy delivery of the posterior shoulder over the perineum.
As the shoulders descend, the head engages the pelvic inlet in a transverse or oblique position. Rotation of the head to the occiput anterior position occurs as it enters the midpelvis. The occiput then slips beneath the pubic symphysis, and the remainder of the head is delivered by flexion as the chin, mouth, nose, and forehead slip over the maternal perineum.
As delivery of the breech occurs, increasingly larger diameters (bitrochanteric, bisacromial, biparietal) of the body enter the pelvis, whereas in cephalic presentation, the largest diameter (biparietal diameter) enters the pelvis first. Particularly in preterm labors, the head is considerably larger than the body and provides a better "dilating wedge" as it passes through the cervix and into the pelvis. The smaller bitrochanteric and bisacromial diameters may descend into the pelvis through a partially dilated cervix, but the larger biparietal diameter may be trapped. Delivery in these cases is described in the following.
Partial Breech Extraction
Partial breech extraction (assisted breech extraction) is used when the operator discerns that spontaneous delivery will not occur or that expeditious delivery is indicated for fetal or maternal reasons. The body is allowed to deliver spontaneously up to the level of the umbilicus. The operator then assists in delivery of the legs, shoulders, arms, and head.
As the umbilicus appears at the maternal perineum, the operator places a finger medial to 1 thigh and then the other thigh, pressing laterally as the fetal pelvis is rotated away from that side by an assistant. Thus, the thigh is externally rotated at the hip and results in flexion of the knee and delivery of one, then the other, leg. The fetal trunk is then wrapped in a towel to support the body. When both scapulae are visible, the body is rotated counterclockwise. The operator locates the right humerus and laterally sweeps the arm across the chest and out the perineum (Fig 21–3). In a similar fashion, the body is rotated clockwise to deliver the left arm. The head then spontaneously delivers by gently lifting the body upward and applying fundal pressure to maintain flexion of the fetal head (Fig 21–4). During partial breech extraction, the anterior shoulder may be difficult to deliver if it is impacted behind the pubic symphysis. In this event, the body is gently lifted upward toward the pubic symphysis, and the operator inserts 1 hand along the hollow of the maternal pelvis and identifies the posterior humerus of the fetus. By gentle downward traction on the humerus, the posterior arm can be easily delivered, thus allowing for easier delivery of the anterior shoulder and arm.
Complications of Breech Delivery
Birth Anoxia
Umbilical cord compression and prolapse may be associated with breech delivery, particularly in complete (5%) and footling (15%) presentations. This is due to the inability of the presenting part to fill the maternal pelvis, either because of prematurity or poor application of the presenting part to the cervix so that the umbilical cord is allowed to prolapse below the level of the breech (see below). Frank breech presentation offers a contoured presenting part, which is better accommodated to the maternal pelvis and is usually well applied to the cervix. The incidence of cord prolapse in frank breech is only 0.5% (the same as for cephalic presentations).
Compression of the prolapsed cord may occur during uterine contractions, causing moderate to severe variable decelerations in the fetal heart rate and leading to fetal anoxia or death. Continuous electronic monitoring is mandatory during labor in these cases to detect ominous decelerations. If they occur, immediate cesarean delivery must be performed.
Birth Injury
The incidence of birth trauma during vaginal breech delivery is 6.7%, 13 times that of cephalic presentations (0.51%). Only high forceps and internal version and extraction procedures have higher rates of birth injury than do vaginal breech deliveries. The types of perinatal injuries reported in breech delivery include tears in the tentorium cerebellum, cephalohematomas, disruption of the spinal cord, brachial palsy, fracture of long bones, and rupture of the sternocleidomastoid muscles. Vaginal breech delivery is the main cause of injuries to the fetal adrenal glands, liver, anus, genitalia, spine, hip joint, sciatic nerve, and musculature of the arms, legs, and back.
Factors contributing to difficult vaginal breech delivery include a partially dilated cervix, unilateral or bilateral nuchal arms, and deflexion of the head. The type of procedure used may affect the neonatal outcome.
Partially Dilated Cervix
Delivery of a breech fetus may progress even though the cervix is only partially dilated because the bitrochanteric and bisacromial diameters are smaller than the biparietal diameter. This is true especially in prematurity. The hips and shoulders may negotiate the cervix, but the aftercoming head becomes entrapped, resulting in difficult delivery and birth injury.
Nuchal Arms
During partial breech extraction and more often in total breech extraction, excessive downward traction on the body results in a single or double nuchal arm. This occurs because of the rapid descent of the body, leading to extension of 1 or both arms, which become lodged behind the neck. When delivery of the shoulder is difficult to accomplish, a nuchal arm should be suspected. To dislodge the arm, the operator rotates the body 180 degrees to bring the elbow toward the face. The humerus can then be identified and delivered by gentle downward traction. In cases of double nuchal arm, the fetus is rotated counterclockwise to dislodge and deliver the right arm and rotated clockwise to deliver the left arm. If this action is unsuccessful, the operator must insert a finger into the pelvis, identify the humerus, and possibly extract the arm, resulting in fracture of the humerus or clavicle. Nuchal arms cause a delay in delivery and increase the incidence of birth asphyxia.
Deflexion of the Head
Hyperextension of the head is defined as deflexion or extension of the head posteriorly beyond the longitudinal axis of the fetus (5% of all breech deliveries). Causes of hyperextension include neck cysts, spasm of the neck musculature, and uterine anomalies, but over 75% have no known cause. Although deflexion may be documented by ultrasonographic or x-ray studies weeks before delivery, there is little apparent risk to the fetus until vaginal delivery is attempted. At that time, deflexion causes impaction of the occipital portion of the head behind the pubic symphysis, which may lead to fractures of the cervical vertebrae, lacerations of the spinal cord, epidural and medullary hemorrhages, and perinatal death. If head deflexion is diagnosed prior to delivery, cesarean section should be performed to avert injury. Cesarean section cannot prevent injuries such as minor meningeal hemorrhage or dislocation of the cervical vertebrae, which may develop in utero secondary to longstanding head deflexion.
Type of Delivery
More complex delivery procedures have a higher rate of birth trauma. Whereas few infants are injured during spontaneous breech births, as many as 6% are injured during partial breech extraction and 20% during total breech extraction. Injuries associated with total breech extraction usually are extensive and severe, and this procedure should never be attempted unless fetal survival is in jeopardy and cesarean section cannot be immediately performed.
An additional important factor in breech injury and perinatal outcome is the experience of the operator. Inexperience may lead to hasty performance of obstetric maneuvers. Delay in delivery may result in birth asphyxia due to umbilical cord compression, but haste in the management of breech delivery results in application of excessive pressure on the fetal body, causing soft-tissue damage and fracture of long bones. Too-rapid extraction of the body from the birth canal causes the arms to extend above the head, resulting in unilateral or bilateral nuchal arms and difficult delivery of the aftercoming head. All breech deliveries should be performed slowly and methodically by experienced obstetricians who execute the maneuvers with gentleness and skill—not speed.
Prognosis
The incidence of cesarean section for breech delivery has been steadily increasing, from approximately 30% in 1970 to 85% in 1999. A recent review of breech deliveries in California revealed an 88% cesarean section rate, with more vaginal deliveries performed in public teaching hospitals and far fewer in private facilities. A decreased number of practitioners currently are skilled in vaginal breech delivery, and although academic faculty support its teaching, there are insufficient numbers of vaginal breech deliveries to properly teach this procedure at most institutions. It should be noted that cesarean section for the immature or malformed fetus does not improve chances for perinatal survival; vaginal delivery should be performed in these cases.
The Term Breech Trial Collaborative Group recently conducted a randomized controlled trial to compare planned cesarean section with vaginal birth for selected breech presentation pregnancies. They found that fetuses of women who underwent planned cesarean sections were less likely to die or to experience poor outcomes in the immediate neonatal period than were fetuses of women who underwent vaginal birth. There was no difference in the 2 groups in terms of maternal mortality or serious morbidity. They concluded that a policy of planned cesarean section will result in 7 cesarean births to avoid 1 infant death or serious morbidity. Because of the results of this trial, the American College of Obstetricians and Gynecologists recommends planned cesarean delivery for persistent breech presentations at term.