OC34.04: Postpartum evaluation of the anal sphincter by transperineal 3D US in primiparous women after normal vaginal delivery and after surgical repair of 3rd‐degree tears

Abstract

Intrapartum damage to the anal sphincter is an important factor in fecal incontinence. Recognized lacerations occur in 0.17–5% of vaginal deliveries, and occult sphincter damage in up to 35% of primiparous women. In the present study we applied 3D transperineal US (3DTUS) in the evaluation of the anal sphincter following normal vaginal delivery and after surgical repair of third-degree intrapartum tears. During 2004–05 93 primiparous women without clinically recognized 3–4 degree anal sphincter tears (Group 1) and 9 primiparous women after surgical repair of third-degree tears with the overlapping technique (Group 2), were prospectively studied 24–72 hours postpartum. A 3D 5–9 MHz transvaginal probe (Voluson 730) was placed in the area of the fourchette and perineal body in transverse and sagittal planes and 2–4 volumes were stored. Parameters studied were examination feasibility, continuity of the internal (IS) and external sphincter (ES), occult damage, width 1.5 cm proximal to the anus at 12–3–6–9 o'clock positions, and IS length. Scanning was possible in all women. Exam time was 2–8 min. IS was consistently visualized in both groups. ES was fully visualized in 72/93 women in Group 1 and in 5/9 in Group 2, and partially visualized in the remainder. In Group 1, mean IS thickness was 0.26, 0.28, 0.27, 0.26 cm at 12–3–6–9 o'clock respectively. Mean ES thickness was 0.2, 0.21, 0.20, 0.22 cm and mean IS length was 3.2 cm. Occult sphincter defect was present in 5/93 women (5%). In Group 2, 3DTUS confirmed continuity defects of the IS and ES in all women in the area between 9 and 3 o'clock. Mean IS thickness was 0.1 cm, 0.22, 0.31, and 0.22cm at 12, 3, 6, and 9 o'clock, respectively. Mean ES thickness was 0.09 cm, 0.24, 0.19, and 0.16 cm at 12, 3, 6, and 9 o'clock, respectively. Mean IS length was 3.04 cm. Compared with Group 1, IS was thinner in the area of damage (0.1 vs. 0.26 cm) and thicker on the opposite side (0.31 vs. 0.27 cm). 3DTUS is an accessible and reliable method for postpartum sphincter evaluation, tolerated by patients. Despite repair with the overlapping technique, thinning in the area of damage and thickening on the opposite side are reliable signs of third-degree intrapartum sphincter tears.