Detection of levator ani trauma with 2D and 3D/4D ultrasound in women after their first vaginal birth – a prospective cohort study

Introduction:

Childbirth related trauma of the pelvic floor, especially of the levator ani muscle, is common after vaginal birth. Levator ani avulsions mainly occur after the first vaginal birth of a woman and are strongly associated with prolapse and prolapse symptoms. The aim of our study was to determine the incidence of levator ani defects in women after their first vaginal birth in our university hospital and to evaluate the feasibility of ultrasound for the detection of levator ani trauma within the first days after birth and after 6 – 10 weeks.

Material and methods:

Between 3/2017 and 1/2019 we included 350 women in our prospective observational study, who planned to give birth vaginally to a singleton in vertex presentation ≥36+0 gestational weeks (gw) at our university hospital. Within the first 2 – 5 days and 6 – 10 weeks postpartum, we performed a 2D and 3D/4D translabial ultrasound examination of the levator ani muscle on both sides (450 muscles in 225 women) and assessed 3 categories of levator ani trauma (complete avulsion, partial avulsion, hematomas/tears within the body of the muscle).

Results:

After excluding cesareans and preterm births before 36 gw, 225 women remained for evaluation. Eleven of them (5%) did not show up for the follow-up examination after 6 – 10 weeks. 70 – 83 women (28 – 37%) were affected by any kind of levator ani trauma, depending on the time of examination and the ultrasound technique used. In the 450 levator ani muscles, we found 25 – 29 partial avulsions on the right side and 28 – 30 on the left side, 10 – 11 complete avulsions on the right side and 8 – 10 on the left side, 4 – 18 hematomas/tears within the muscle body on the right side and 1 – 20 on the left side. For partial and complete avulsions, the accordance between 2D and 3D/4D ultrasound and between the 2 evaluation periods was very good. For hematomas/tears within the muscle body the accordance between the two ultrasound techniques was also good, but not between the two evaluation periods. Much less hematomas/tears within the muscle body were found after 6 – 10 weeks. 24 – 32 women (11 – 14%) suffered from any kind of bilateral levator ani trauma, including 23 – 24 women (10 – 11%) with bilateral partial or complete avulsions. Translabial ultrasound was technically not feasible or inconclusive in 1 – 4 women (0.4 – 2%).

Discussion:

Levator ani avulsions and trauma frequently occur after the first vaginal birth and are almost equally distributed between the right and the left body side. Accordance between the two different ultrasound techniques and evaluation periods is good. Levator ani trauma can reliably be diagnosed with translabial ultrasound already during the hospital stay within the first days after a vaginal birth. Nevertheless, some of the trauma diagnosed within the first postpartum days might be categorized incorrectly, as discrimination between hematoma and (partial) avulsion is sometimes difficult at that time.