Overlapping sphincteroplasty: does preservation of the scar influence immediate outcome?

BACKGROUND: The importance of the overlapping scar in an anterior sphincteroplasty is often emphasized. The aim of this study was to identify the tissue type used in overlapping sphincter repair based upon ultrasound images, and to correlate these results with the immediate clinical outcome. METHODS: Data were collected prospectively on all patients with faecal incontinence who underwent anterior overlapping sphincteroplasty between June 1998 and May 1999. Continence was assessed by a standardized incontinence score ranging from 0 to 20. Pre-operative ultrasound images were compared to intraoperative ultrasound findings for each patient. In each case the surgeon performed an overlap of what was grossly felt to represent scar after which a single blinded observer performed intraoperative ultrasound. The degree of overlap was measured and classified as hyperechoic over hyperechoic (muscle over muscle; Type 1), hyperechoic over or under hypoechoic (muscle over or under scar; Type 2), hypoechoic over hypoechoic (scar over scar; Type 3). The patient follow-up included incontinence score that was obtained by telephone interview; suboptimal outcome was considered as an incontinence score >/= 6. Statistical analysis was performed using the Mann-Whitney test and Wilcoxon matched-pairs test. RESULTS: Fourteen female patients with a mean age of 51.6 (range 28-79) years were evaluated. The mean pre-operative incontinence score was 17.1 (range 7-20) and 13 of the 14 (93%) patients had an incontinence score >/= 15. All pre-operative ultrasound images were hypoechoic which correlated with the surgeon's intraoperative findings of scar. The operative appearance included two Type 1, four Type 2, and eight Type 3 images. Larger pre-operative ultrasound image defects were statistically significantly related to intraoperative Type 3 ultrasound images. At a mean follow up of 7.5 (range 2-16) months the mean postoperative incontinence score was 4.5 (range 0-12). In patients with Type 1 and Type 2 images, the mean postoperative score was 8.6 (range 4-12) whereas in patients with Type 3 it was 1.3 (range 0-5) (P < 0.003); 7 of the 8 patients in Type 3 (87.5%) had an incontinence score </= 2. CONCLUSION: These preliminary results show a significant immediate benefit to the overlap of scar over scar, however, such overlapping may not always be achieved despite the surgeon's intent. Furthermore, larger pre-operative defects may predispose to more extensive anterior scarring and thus a better chance of achieving this desired overlap.