Role of Intrapartum Ultrasound in Instrumental Delivery

Investigators will perform a multicentric randomized controlled trial comparing the effect of transabdominal and transperineal ultrasound in pregnant women in the second stage of labor, in whom it was decided an operative delivery. Our objective is to evaluate the impact of intrapartal ultrasound measurements, as an auxiliary to clinical evaluation, in the efficacy of an instrumental delivery.

The study group will be constituted by pregnant women in whom the operative delivery will be preceded by a transabdominal and transperineal ultrasound to evaluate fetal head position and fetal head station, by means of determination of the 'angle of progression'.

The control group will be constituted by pregnant women in whom the operative delivery will be carried out based solely on clinical criteria, namely transvaginal digital examination.

Transabdominal ultrasound, for determining fetal head position, is performed with the pregnant women in supine position after bladder emptying, with the transducer placed transversely on the suprapubic region of the maternal abdomen. For the sonographic determination of the fetal descent we will perform a transperineal ultrasound achieved by placing the ultrasound transducer on the perineum in a mid sagittal position between the labia below the pubic symphysis.

low 5-minute Apgar score, umbilical artery metabolic acidosis, birth trauma and neonatal intensive care unit admission

Inclusion Criteria: pregnant women at term, in labor (≥ 37 weeks of gestation dated by a first trimester ultrasound live singleton pregnancy fetus in a cephalic presentation in the second stage of labor, after the decision to perform an instrumental delivery Exclusion Criteria: fetal malformations emergency situation