Outcome of primary repair of obstetric anal sphincter injuries (OASIS) - does the grade of tear matter?

OBJECTIVES:: The aim was to assess risk factors and outcome of different grades of obstetric anal sphincter injuries (OASIS) after primary repair, and secondly to assess the relationship between outcome and anal sphincter defects, as diagnosed with endoanal ultrasound. METHODS:: Included were 531 consecutive women (including 8 tertiary referrals) who sustained OASIS and were followed-up between July 2002 and July 2008. At follow up defecatory symptoms and bowel related Quality of Life (QoL) were evaluated. Anal manometry and endoanal ultrasound were performed. RESULTS:: Mean follow-up was 9 weeks (SD 5.9) after delivery. Compared to a minor (grade 3a/3b) tear a major (3c/4(th) degree) tear had a significantly poorer outcome (p<0.05) with respect to the development of defecatory symptoms and associated QoL as well as anal manometry. Women with major tears were significantly more likely to have an endosonographic isolated internal anal sphincter (IAS) or combined IAS and external anal sphincter (EAS) defect. Combined defects were associated with a higher risk of incontinence of loose stool and lower anal canal pressures. Epidural use was the only independent factor predicting a major tear. CONCLUSIONS:: The finding of more endosongraphic anal sphincter defects in women with major tears compared to minor tears is the probable cause of a less favorable outcome of primary repair. Endosonographic combined defects are associated with poorer outcome and it is therefore important to identify the full extent of injury at delivery in women who sustain OASIS, paying particular attention to the repair of the disrupted IAS. Copyright (c) 2009 ISUOG. Published by John Wiley & Sons, Ltd.