Nuriya D. Robinson
Breech presentation is defined as the fetus in a longitudinal lie whose buttocks, knees, or feet are adjacent to the cervix. The prevalence of breech presentation is inversely proportional to fetal gestational age, occurring 25% to 30% at 28 weeks or less, 7% at 32 weeks, and 3% to 4% at term deliveries.1 This represents the most common fetal malpresentation, necessitating emergency medicine providers to acquire and maintain the skills necessary to perform a vaginal breech delivery. The most serious complication with a breech delivery, especially in a preterm infant, is head entrapment. In normal labor, the head, which is the largest part of the infant, presents first and dilates the cervix, but with a breech presentation the head may become entrapped due to an incompletely dilated cervix.
The majority of breech presentations develop by chance; however, breech presentation is more likely in the presence of maternal, fetal, or placental abnormalities. The most common pathologies resulting in breech presentation are those that disturb fetal movement or the polarity of the uterine cavity. Risk factors for breech presentation include preterm gestation, prior breech delivery, uterine abnormalities (i.e., leiomyoma, septate uterus), placental abnormalities (i.e., placenta previa), multiparity, aneuploidies, poly- and oligohydramnios, fetal anomalies (i.e., goiter, hydrocephaly), multiple gestation, extended fetal legs, contracted maternal pelvis, fetal growth restriction, short umbilical cord, and older maternal age.2
CLASSIFICATION OF BREECH PRESENTATIONS
There are three main types of breech presentation. The frank breech is the most common, accounting for 50% to 70% of breech fetuses. In this position, the hips are flexed and the knees are extended, so that the feet are neighboring the fetal head with the infant in a pike position. The footling or incomplete breech is the second most common, making up 10% to 40% of breech fetuses. One or both hips or knees are not completely flexed, resulting in one or both feet presenting before the buttocks. Finally, in the complete breech position, both the hips and knees are flexed. This is the least common and represents 5% to 10% of breech fetuses (see Figure 22.1).3
RISKS OF BREECH DELIVERY
The literature suggests that vaginal breech deliveries pose a higher risk to the neonate than planned cesarean birth. When planned vaginal breech delivery is compared with planned cesarean delivery, there is a higher risk of perinatal mortality, serious neonatal morbidity (including hypoxic and traumatic injuries), and neonatal mortality in the breech group.4 However, in the appropriately selected patient and with specific management protocols, there are instances where vaginal breech and cesarean delivery outcomes are identical.
The following criteria portend a higher likelihood of having a safe and successful vaginal breech delivery5:
No contraindication to vaginal birth (e.g., placenta previa, cord presentation)
Gestational age equal to 36 weeks or more
No prior cesarean deliveries
Frank or complete breech presentation
Estimated fetal weight greater than or equal to 2000 g and less than or equal to 4000 g
No hyperextension of the fetal head
Absence of fetal anomaly
Alternatively, there are several instances in which a vaginal breech delivery is contraindicated—except in emergent situations—and the mother would benefit from a cesarean section.6,7,8
Preterm Fetus: A fetus of less than 36 weeks’ gestation is generally seen as a contraindication for vaginal delivery due to increased risk of neonatal mortality and delivery complications.9 A smaller part can slip through the incompletely dilated cervix, leading to head entrapment or cord compression. Both of these complications can cause asphyxia and fetal compromise. However, if delivery is imminent and there is no time to arrange for cesarean delivery, rupturing of the membranes should be delayed until the fetus has passed through the vagina. This reduces the risk of head entrapment by an insufficiently dilated cervix, protects the fetus from trauma, and prevents cord prolapse.10
Incomplete Breech: Ideally, vaginal delivery should only be attempted on frank or complete breech presentations. In a complete breech at term, the fetal lower legs, thighs, and trunk are the presenting part and these are large enough to cause cervical dilation, making the risk of head entrapment less likely. Similarly, in the frank breech presentation, the thighs and the trunk are the presenting parts. However, in footling breech presentations, the presenting part is smaller and can pass through an incompletely dilated cervix or small pelvis, which can lead to head entrapment. Hence, footling breech deliveries are generally limited to the delivery of a second twin.5
Fetal Growth Restriction or Macrosomia: A growth-restricted fetus has a high likelihood of metabolic acidemia during labor due to an already compromised placental function reducing fetal tolerance to cord compression during expulsion. In contrast, a normal fetus is well oxygenated and may tolerate a few minutes of extrinsic cord compression.6 Half of the perinatal deaths in the Term Breech Trial, a large multicenter randomized controlled trial comparing outcomes of planned vaginal breech with planned cesarean section for breech, were growth-restricted fetuses.8 Therefore, growth-restricted fetuses should be delivered via cesarean section.
Cord Prolapse: A fetus with cord prolapse is a general contraindication for vaginal delivery due to concern of cord rupture and asphyxia. Cord prolapse detection with timely access to cesarean section has been associated with good fetal outcome.11,12
Congenital Malformation: If any congenital malformation or anatomic variant is known, it is safer for the patient to undergo cesarean section to avoid the possibility of dystocia or fetal entrapment through the vaginal canal.
Prolonged Vaginal Delivery: Failure to deliver a breech fetus with adequate maternal pushing after 60 minutes is an indication for cesarean delivery given the increased risk of neonatal morbidity.8
Based on available evidence, the best mode of delivery for fetuses in the breech presentation remains controversial. The American College of Obstetricians and Gynecologists recommends that the mode of delivery should depend on the competence/experience of individual providers in conjunction with hospital inclusion criteria.13 However, in the emergency department setting, a pregnant woman may present in active labor with a fetus in the breech presentation. The decision regarding mode of delivery will depend on whether delivery is imminent or whether there is time to arrange for cesarean delivery. Additionally, the emergency provider may need to take into account acute situations such as fetal distress or lack of resources (i.e., surgical specialties). In these situations, a vaginal breech delivery may be indicated. Familiarity with recognizing breech presentation as well as breech delivery techniques promotes success in these emergent circumstances.
Diagnostic evaluation of a suspected breech presentation begins with the physical examination. Palpation of the rounded fetal head at the fundus and/or the inability to palpate a presenting part in the lower abdomen (i.e., superior to the pubic bone) would suggest breech presentation. For diagnostic accuracy, an abdominal examination should be used in conjunction with a vaginal examination. Findings suggestive of breech presentation on vaginal examination include palpation of a buttocks, lower extremity, or complete lack of a palpable fetal presenting part. These clinical examination findings are imperfect as they may be obscured by maternal habitus, uterine abnormalities, or fetal/placental variability.14 The most rapid and accurate bedside examination by the emergency provider is the point-of-care ultrasound. Fetal transabdominal ultrasound easily identifies the fetal head at the fundus and/or the buttocks/lower extremities in the lower uterine segment. It is also important to gather specific information with the ultrasound regarding the type of breech and placental lie/location if time allows.
Once a fetus in breech presentation is identified on examination either through ultrasound or by performing a transvaginal examination and palpating buttocks or limbs, it is critical to determine whether the delivery is imminent and to contact obstetric and pediatric providers immediately. The delivery requires care of two patients, both the fetus and the mother. A physician skilled in neonatal resuscitation should ideally be present at the time of delivery. Mobilize the appropriate resources at your facility.
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