Sonographic detection of a nuchal arm in the intrapartum assessment of the breech-presenting fetus

Abstract

of the breech-presenting fetus is currently applied in many obstetrical services, replacing traditional abdominal radiographic evaluation of the fetus during the first stage of labor. In addition to the type of breech presentation (frank, complete, or incomplete) and estimated fetal weight, further information that Figure 1 Sonographic documentation of a nuchal arm. A, Longitudinal scan. Vtx, Fetal head; sp, fetal spine; curved arrow, fetal digits. 8, Transverse scan. Note foramen magnum in posterior fossa indicating fetal occipital area (curved arrow, fetal digits). 524can be gleaned from this sonographic examination includes assessment of the intracranial fetal anatomy and delineation of the precise positioning of the fetal head 1 (hyperextension of the fetal head is an indication for abdominal delivery).Extension of an arm in the breech-presenting fetus with its positioning behind the fetal head is termed a nuchal arm.2 The occurrence of a nuchal arm during the second stage of labor often may lead to fetal trauma during attempts to reduce the arm at delivery and constitutes a well-recognized severe complication encountered in vaginal breech deliveries.2.3 Radiologic documentation of a nuchal arm in the first stage of labor has been suggested as a additional indication for abdominal delivery.4 This important information can also be obtained sonographically.Recently, while performing a third trimester sonographic examination of a breech-presenting fetus (using AI Model5200, Acoustic Imaging, Phoenix, AZ), we documented the fetal hand in dose proximity to the occipital area (Fig. 1). This positioning 1 if persistent, is indicative of an extended nuchal arm and constitutes information that should be forwarded to the obstetrician prior to the decision on the recommended mode of delivery.