Intrapartum translabial three-dimensional ultrasound visualization of levator trauma

The aim of this study was to visualize levator trauma by three-dimensional (3D) ultrasound performed during labor and soon after the crowning of the fetal head and to determine how often levator trauma occurs.

This was a prospective, observational study of 66 women enrolled during the first stage of labor. The women underwent intrapartum 3D transperineal ultrasound examination during the first and second stages of labor and within 12 h after delivery. Volume datasets were acquired and analyzed to determine the presence of levator trauma.

Data from 10 of the 66 women were excluded from analysis-nine because they underwent Cesarean section in the first or second stage of labor and one because she underwent hysterectomy and no postpartum volumes were collected. Thus our study group comprised 56 women-35 nulliparous and 21 parous. A total of 504 volumes were collected in the 56 women (three volumes for each stage of labor). One hundred and twenty levator volumes were excluded from analysis, but volumes of acceptable quality were available for all three stages of labor in all women. Eleven (31.4%) of the 35 nulliparae had levator lesions detected postpartum and none of them had levator lesions before delivery. Five (23.8%) of the 21 parous women had a levator tear detected in their postpartum volumes. In two of these five women the levator tear was also present in both volumes taken during labor.

Visualization of the levator ani during labor by 3D ultrasound examination is feasible. Comparison of volumes obtained during labor and within the first 2 h after delivery supports the theory that crowning of the head is the immediate cause of avulsion of the levator ani muscle.