Transperineal US: alternative technique to improve visualization of the presenting fetal part.

Transperineal ultrasound (TPU) was used as an alternative imaging technique to evaluate the anatomy of the presenting part in 27 second- and third-trimester fetuses when transabdominal ultrasound (US) images were suboptimal. Use of TPU improved visualization of the distal fetal spine in 20 of 21 breech cases, providing sufficient information regarding bone anatomy to rule out splaying of the posterior elements. In addition, the intact skin surface overlying the distal spine, not seen at transabdominal US, was well demonstrated at TPU in 18 of these fetuses. TPU was used to improve assessment of intracranial anatomy in six cases with a cephalic presentation in which the fetal head was located low in the maternal pelvis and could not be adequately visualized with the transabdominal technique. In one of these cases, TPU offered improved visualization of anencephaly. Use of TPU should be considered to optimize visualization of the presenting fetal part when results at transabdominal US are suboptimal and the poorly seen part overlies the maternal cervix.