Endosonography of the anal spincter in women with particular reference to obstetric sphincter tears

Sammanfattning: The aim of this thesis was to study the endosonographic morphology of the anal sphincter in women, to establish an endosonographic sphincter defect score and to relate it to anal incontinence and anal sphincter pressure. A further aim was to determine intra-observer and inter-observer agreement in detection of endosonographic anal sphincter defects. An endosonographic anal sphincter defect classification system in women with known or unknown sphincter trauma and reference data representative of normal findings at anal endosonography in women has been established. The normal findings did not differ between nonpregnant nulliparous and parous women and did not change substantially with age. The internal sphincter was thickest at 9 o’clock, and the external sphincter was thinnest at 12 o’clock. Both endosonographic sphincter defects and minor gas incontinence were common in women without known sphincter trauma but were unrelated to each other. Small endosonographic anal sphincter defects were common (13%) in pregnant nulliparous women in the third trimester of pregnancy, and we also found new sphincter defects after vaginal delivery without a clinically recognizable sphincter tear. Episiotomy increased the risk of new defects. The larger the new defect the higher the anal incontinence score. Ninety per cent of women with a clinical third- or fourth-degree perineal tear had endosonographic sphincter defects at one week, three months and one year after primary suture. The extent of the endosonographic defects 2-7 days after primary repair, seemed to be determined mainly by the surgical experience of the doctor performing the repair and not by the clinical degree of the tear. There was a positive correlation between endosonographic sphincter defect score at one week, three months and one year and the Wexner incontinence score at one year and four years. The endosonographic sphincter score at one week was the variable most predictive of anal incontinence score at four years. This suggests that it maybe worth repairing an obstetric sphincter tear with as good an endosonographic result as possible. There was a good intra- and inter-observer agreement in detection of endosonographic anal sphincter defects.