For the fetus, prematurity and its complications are frequently comorbid with breech presentation. Rates of congenital anomalies are also greater (Cammu, 2014; Mostello, 2014). Compared with cephalic presentation, umbilical cord prolapse is more frequent with breech fetuses (Behbehani, 2016; Obeidat, 2010). Birth trauma can include fractures of the humerus, clavicle, and femur (Canpolat, 2010; Matsubara, 2008). In some cases, traction may separate scapular, humeral, or femoral epiphyses (Lamrani, 2011). Trauma is more common with vaginal births, but fetal trauma is also seen with cesarean deliveries.
Rare traumatic injuries may involve soft tissues. Brachial plexus injury and paralysis is one example (Foad, 2008). The spinal cord may be injured or even severed, or vertebrae fractured, especially if great force is employed (Vialle, 2007). Hematomas of the sternocleidomastoid muscles occasionally develop after delivery but usually disappear spontaneously. Last, genital injury may follow breech delivery (Saroha, 2015).
Some perinatal outcomes may be inherent to the breech position rather than delivery. For example, development of hip dysplasia is more common in breech compared with cephalic presentation and is unafected by delivery mode (de Hundt, 2012; Fox, 2010; Ortiz-Neira, 2012).
In many fetuses-especially those that are preterm-the breech is smaller than the atercoming head. Moreover, unlike cephalic presentations, the head of a breech-presenting fetus does not undergo appreciable molding during labor. Thus, if vaginal delivery is considered, fetal size, type of breech, and degree of neck lexion or extension are evaluated. In addition, pelvic dimensions are assessed to avoid head entrapment from cephalopelvic disproportion. Sonography and fetal pelvimetry are options.
Sonographic fetal evaluation will have been performed in most cases as part of prenatal care. If not, gross fetal abnormalities, such as hydrocephaly or anencephaly, can be rapidly ascertained with sonography. This will identiy many fetuses not suitable for vaginal delivery. It will also help to ensure that a cesarean delivery is not performed under emergency conditions for an anomalous fetus with no chance of survival.
Head flexion can usually also be determined sonographically, and for vaginal delivery, the fetal head should not be extended (Fontenot, 1997; Rojansky, 1994). If imaging is uncertain, then simple two-view radiography of the maternal abdomen is useful to define fetal head inclination. Sonographic identification of a nuchal arm may warrant cesarean delivery to avoid neonatal harm (Sherer, 1989).
he accuracy of fetal weight estimation by sonography is not altered by breech presentation (McNamara, 2012). Although variable, many protocols use fetal weights >2500 g and <3800 to 4000 g or evidence of growth restriction as exclusion criteria for planned vaginal delivery (Azria, 2012; Kotaska, 2009). Similarly, a biparietal diameter (BPD) >90 to 100 mm is often considered exclusionary (Giuliani, 2002; Roman, 2008).