Objective: Evaluation of the influence of vaginal childbirth on the integrity of the puborectalis muscle with the help of real-time 3D ultrasound. Design: Prospective pilot study. Setting: Institute for Care for Mother and Child, Prague, Czech Republic. Material and Methods: We examined 20 primigravid women in the third trimester and on the third day after vaginal delivery. The transperineal 3D ultrasound examination was performed and the data were evaluated afterwards in the 4D view© software. The VCI (Volume Contrast Imaging) mode with slice thickness 3 millimeters was used for analysis. We evaluated the integrity of the puborectalis muscle on both sides, the quality of the images and the presence of hematomas. Results: The examination before delivery did not show any abnormal anatomy of the examined region. We found four (20%) unilateral defects and one (5%) bilateral puborectalis avulsion after the delivery. The bilateral defect was after the forceps delivery, the other defects occurred after normal uncomplicated vaginal deliveries, where only left mediolateral episiotomy was performed and the birth weight did not exceed 3700 g. In our series, 25% of women suffered an injury of a major muscle of pelvic floor. No defect was diagnosed during the delivery and did not show any connection with the episiotomy. Conclusions: 3D ultrasound can detect major birth trauma to the puborectalis muscle. The puborectalis muscle avulsion is usually not recognized during the delivery and does not cause immediate problem to the patient.

        Key words: 3D ultrasound, birth trauma, prolapse, levator ani, stress urinary incontinence