Tridimensional sonographic anatomical changes on pelvic floor muscle according to the type of delivery

Introduction and hypothesis The aim of the study was to evaluate the association of avulsion and postnatal hiatal dimensions with delivery mode. These anatomical changes on pelvic floor muscle may be assessed by 3–4D ultrasonography. Methods This is a prospective observational study that included 164 women: 20 nulliparous, 20 primigravid, and 124 postpartum women (62 at 1 month, 62 at 9 months postpartum). We performed an introital 3–4D ultrasonography to assess levator ani muscle's integrity, levator hiatal area at rest, on Valsalva, and on contraction. Results Levator ani avulsion was diagnosed in 59.5% of forceps deliveries. There were no statistically significant differences in postnatal hiatal dimensions between normal vaginal deliveries at 9 months postpartum and nulligravid. Levator hiatal area was significantly higher after forceps delivery. Conclusion Low incidence of levator avulsion takes place in normal vaginal deliveries. However, forceps delivery is the riskiest type of delivery for pelvic floor pathology and its recovery.