ABSTRACT
Isolated tears of the rectal mucosa without involvement of the anal sphincter ( Fig. 85.2 ) are a rare event and should not be included in the above classification.
incidence of oasis and outcome of repair The reported incidence of OASIS varies from one unit to the next and is dependent on obstetric practice but is especially related to the type of episiotomy practiced. OASIS are reported to occur between 0.5% in earlier studies ( 10 , 11 ) and 7.5% ( 12 ) of deliveries in centers where mediolateral episiotomy is practiced. It has been reported in 16% of instrumental deliveries ( 13 ) and 11% ( 14 ) [19% in primiparae ( 15 )] in centers where midline episiotomy is practiced. Midline episiotomies have been favored in North American practice while mediolateral episiotomies are favored in Europe. Over a 25 year period between 1980 and 2005, 35 studies have evaluated outcome following OASIS with follow-up ranging from one to 36 months ( Table 85.1 ) ( 16 ). The prevalence of anal incontinence (including flatus as a sole symptom) and fecal incontinence (liquids and solids with or without flatus) following end to end repair ranges between 15% and 61% (n = 35; mean = 39%) and 2% and 29% (n = 25; mean = 14%), respectively ( Table 85.1 ). In addition, fecal urgency can affect a further 6% ( 10 , 46 ) to 28% ( 48 ) of women. Despite repair, persistent sonographic anal sphincter defects were identified in 34% ( 23 ) to 91% ( 46 ) of women. Anal incontinence during coitus occurs in about 17% of women following OASIS ( 44 ).
