Colorectal 25

Aims: To assess anal sphincter structure and functional outcomes following third-degree perineal tears and the effect of its disruption on the development of anal incontinence. Methods: Fifty-one consecutive patients, 41 primigravidae and 10 multigravidae, with third-degree intrapartum perineal tears, primarily repaired, were recruited 4 months postpartum. Patients completed questionnaires assessing faecal incontinence. Anal manometry and endosonography were then performed. Results: No patient reported incontinence prior to pregnancy. The incidence of faecal incontinence was 12 per cent. Six patients were incontinent of faeces and 10 incontinent of either flatus and/or fluid. Eighty-one per cent of anal incontinent patients were primigravidae (OR 0.96). Three women had previous third-degree tears, with one anal incontinence on subsequent delivery. Disruption of the external anal sphincter (EAS) was identified endosonographically in 26 patients. In 13 patients, there was an associated internal anal sphincter (IAS) defect. Clinically unsuspected tears of the Anal sphincter mechanism were diagnosed by anal endosonography in 46 per cent of asymptomatic patients. The EAS alone was involved in 14, IAS in three, and both in five patients. Clinical examination of women with anal incontinence identified an anal sphincter defect in 46 per cent. Ultrasound in anal incontinent patients showed an IAS defect in 42 per cent and an EAS defect in 52 per cent. All patients with faecal incontinence had a disruption of the EAS identified by endosonography (P < 0.05). No significant relationship was demonstrated between symptoms and anal manometry (P = 1.0, n.s.). Conclusions: Third-degree tears cause significant, although clinically unsuspected anal sphincter defects. It may be that anal manometry alone is not sufficient to exclude sphincter injury.