EFFECT OF VAGINAL DELIVERY ON THE ANAL SPHINCTERS

Sphincter tears: Vaginal delivery can lead to tears in the anal sphinc ters. Total perineal distension following expulsion concerns less than 1% of all deliveries. Initially, sphincter tears generally go unnotic ed although echographically detectable defects can be found in one-thi rd of all primiparturients. The inner or outer sphincter may be involv ed alone or in combination as is seen in half of the cases. Neurologic al lesions: Moderate signs of incontinence (gas, urge) are frequently reversible although the long-term outcome remains unknown. In half of the cases, perineal denervation is secondary to stretch lesions of the pudendal nerve terminasions. Favoring factors: Primiparity, forceps d elivery, fetal macrosomy, and certain presentations (breech, occipitop osterior) may favor sphincter lesions. Diagnosis: A complete examinati on of the posterior perineum is required with anorectal manometry, a p erineal electrophysiologic study, and a transanal ultrasound study whe never function signs are found at the post partum follow-up. Treatment : The therapeutic strategy is guided by the exploration results. In ca se of symptomatic rupture of the external sphincter, sphicteroplasty i s needed followed by functional rehabilitation therapy with biofeedbac k. Women who have suffered traumatic lesions of the posterior perineum should be carefully followed for signs of secondary incontinence. Ces arean section may be indicated as a preventive measure in case of a ne w pregnancy.