Breech presentation occurs in about 2% of singleton de-liveries at term and more frequently in the early third and second trimesters. In addition to prematurity, other condi-tions associated with breech presentation include multiple pregnancy, polyhydramnios, hydrocephaly, anencephaly, aneuploidy, uterine anomalies, and uterine tumors. The three kinds of breech presentation—frank, complete, and incomplete breech (Fig. 9.6)—are diagnosed by a combi-nation of Leopold maneuvers, pelvic examination, ultra-sonography, and other imaging techniques (Fig. 9.7). Themorbidity and mortality rates for mother and fetus, regardless of gestational age or mode of delivery, are higher in the breech than in the cephalic presentation. This increased risk to the fetuscomes from associated factors such as fetal anomalies, prematurity, and umbilical cord prolapse, as well as birth trauma.
External cephalic version (ECV) involves applyingpressure to the mother’s abdomen to turn the fetus in either a forward or backward somersault to achieve a vertex pre-sentation prior to labor (Fig. 9.8). The goal of ECV is to increase the proportion of vertex presentations among fe-tuses that were formerly in the breech position near term. Once a vertex presentation is achieved, the chances for a vaginal delivery increase. This maneuver is successful in ap-proximately half of properly selected cases. Patients who havecompleted 36 weeks of gestation are preferred candidates for ECV for several reasons. First, if spontaneous version is going to occur, it is likely to have taken place by 36 com-pleted weeks of gestation. Second, risk of a spontaneous reversion is decreased after external cephalic version at term compared with earlier gestations. Selection criteria in-clude a normal fetus with reassuring fetal heart tracing, ade-quate amniotic fluid, presenting part not in the pelvis, and no uterine operative scars. The risks include premature rup-ture of membranes, placental abruption, cord accident, and uterine rupture. External version is more often suc-cessful in parous women. Existing evidence may support theuse of a tocolytic agent (a drug that stops uterine contractions) during ECV attempts, particularly in nulliparous patients
Administration of anti-D immune globulin to Rh negative women is recommended.
In light of recent studies that further clarify the long-term risks of vaginal breech delivery, the decision regard-ing mode of delivery should depend on the experience of the healthcare provider. Cesarean delivery will be the pre-ferred mode for most physicians because of the diminishing ex-pertise in vaginal breech delivery. Planned vaginal delivery ofa term singleton breech fetus may be reasonable under hospital-specific protocol guidelines for both eligibility and labor management. The following criteria have been suggested for vaginal breech delivery:
· Normal labor curve
· Gestational age greater than 37 weeks
· Frank or complete breech presentation. Because of the risk of umbilical cord prolapse, vaginal delivery of a fetus in the footling breech position is not recommended.
· Absence of fetal anomalies on ultrasound examination
· Adequate maternal pelvis
· Estimated fetal weight between 2500 g and 4000 g
· Documentation of fetal head flexion. Hyperextension of the fetal head occurs in about 5% of term breech fetuses, requiring cesarean delivery to avoid head entrapment.
· Adequate amniotic fluid volume (defined as a 3-cm ver-tical pocket)
· Availability of anesthesia and neonatal support
If a vaginal breech delivery is planned, the woman should be informed that the risk of perinatal or neonatal mortality or short-term serious neonatal morbidity may be higher in it than in a cesarean delivery, and the patient’s informed consent should be documented.