Recto-perineal fistula is a common anorectal anomaly in which the anus is abnormally located in the perineum anterior to the center of the muscle complex. Usually, a part of the anal canal is present within the sphincter mechanism, so most of these patients would be expected to have a good chance for fecal continence after the repair . However, fecal soiling can occur in some of these patients usually associating severe constipation (over retentive stool incontinence; ORSI) .
Management of recto-perineal fistula is controversial. Some surgeons prefer not to do surgical correction especially when the fistula is sufficiently wide because they assume that there is a high incidence of postoperative constipation that would make surgery of little or no value. Others would prefer prolonged regular dilatation for managing a narrow fistula . Surgical options for recto-perineal fistula include simple anoplasties (Y-V anoplasty; cut-back; posterior anoplasty) and limited posterior sagittal anorectoplasty (PSARP). Hendren described his technique of posterior anoplasty that include incomplete circumferential incision around the anus (from 1 to 11 o’clock position). He reported successful outcome in treating constipation with a relatively lower risk of wound complications . However, simple anoplasties may be suitable only for cases with mild anterior anal displacement [10, 15]. On the other hand, limited PSARP can be used to correct all degrees of recto-perineal fistulae by complete mobilization and repositioning of the anorectum backwards within the muscle complex, but this may be associated with a higher risk of wound dehiscence and anal retraction that may necessitate temporary fecal diversion (colostomy) [11, 12].
One reason for this study was to answer the following question: Does limited PSARP have a role in treating or improving constipation in patients with recto-perineal fistula?
Constipation is a common finding after surgical repair of low anorectal anomalies. The reason for constipation is unclear and it seems to occur regardless of the used surgical technique [3, 16]. Preoperative constipation rate in our study was 77% (23/30) which has been improved after limited SARP to 30% (9/30). This postoperative constipation rate is lower than many reported studies [3, 4, 16]. Constipation before and after the repair was graded according to Krickenbeck classification . Most of the cases who had preoperative constipation (14/23) were treated from constipation. One case (1/23) has been improved as regard constipation grade (from grade 3 to grade 2). The remaining 8 cases (8/23) are still having the same degree of constipation. According to these results, repair of recto-perineal fistula by limited PSARP treat or at least improve constipation in about two third of cases who were suffering from constipation.
We do agree that the severity of constipation can change with time as patients go older, but this is not expected to occur during the early years of life. Kyrklund et al. reported significant constipation among cases of recto-perineal fistula treated by simple anoplasties; however, significant improvement of constipation was noticed at follow-up in older children (> 12 years of age) . In our study, most operations were performed in infancy and were followed by improvement of constipation in this young age group that would suggest the effect to be directly related to surgery. Although we cannot exclude a possible “halo” effect of the surgical procedure that may result in some symptomatic improvement; however, this halo effect should be temporary and not expected to persist (median follow-up in our study was 40 months). Another possible external influence may be related to postoperative dietary change. In our study group, weaning from breastfeeding was a common dietary change after operation influenced by the period of perioperative fasting. This would probably aggravate constipation rather than improve it.
From previous studies, we have learned that constipation in anorectal anomalies may be attributed to multiple factors (anterior anal displacement, narrow anus, colonic dysmotility, neurogenic factors) . Among these factors, the abnormal anterior displacement of the anal canal within the pelvic muscles can disturb the normal orientation of the longitudinal axis of anal canal in relation to the surrounding vector forces created by these muscles during defecation . A potential benefit of surgery (limited PSARP) is restoring the normal orientation of the anal canal within the pelvic musculature that can explain improvement of constipation in these cases after operation [7, 19]. Another possible beneficial effect of surgery would be removing of a stenotic termination of the recto-perineal fistula, which we have noticed to be more common in male patients.
Soiling is defined as fecal staining of underwear which occurs because of defects in the sphincteric mechanism or as a consequence of protracted constipation (overflow incontinence) [20, 21]. Previous studies reported soiling rate in low anorectal anomalies ranging from 9 to 48% [3, 4, 16]. In our study group, seven cases (23%) had soiling; all of them were constipated. Treatment of constipation by stimulant laxatives (Senna derivatives) markedly improved soiling in all cases that would suggest the cause of soiling in these patients to be due to overflow (pseudo-incontinence) rather than true incontinence from sphincteric defects.
Wound dehiscence at the mucocutaneous junction after sagittal anorectoplasty is a common complication [9, 22], that may lead to delayed functional sequelae (constipation and soiling) . However, in this study we could not find significant correlation between the occurrence of wound dehiscence and delayed functional sequelae. We reported 6 patients (20%) with wound dehiscence; 3 cases had minor dehiscence which was managed non-operatively, another case of minor dehiscence was managed by secondary sutures, and 2 cases had major dehiscence that needed covering colostomy and secondary sutures. From all cases with wound dehiscence, only one case had persistent postoperative constipation.
Some scholars question the value of limited PSARP in the repair of recto-perineal fistula and may consider it a sort of overdoing , also it raises the concern toward sphincter muscle dissection and possibility of true incontinence which is not found among our patients. To answer this question, it may be more appropriate to compare the repaired cohort with an unrepaired cohort, as well as comparing limited PSARP with other simpler anoplasties. However, in this report, we tried to address this issue from a different perspective by comparing constipation in the same subject before and after the repair. The study still may be criticized for the small sample size and absence of long-term follow-up in all cases which is important to get more representative results about delayed functional sequelae.