Restorative Proctocolectomy Ileo Pouch Anal Anastomosis IPAA

The interest in IRA may well have declined with the advent of proctocolectomy and the ileo pouch-anal anastomosis (IPAA). IPAA or restorative procto-colectomy, i.e. construction of a reservoir of distal ileum and an ileo pouch-anal anastomosis is the current most popular option for surgical treatment of ulcerative proctocolitis. There is no stoma or need for an external bag and the normal route of defecation is preserved, i.e. a normal body image. It has become the first choice operation to be recommended around the world. In the conventional technique, colectomy is combined with endoanal mucous proc-tectomy and the ileal pouch is hand-sewn to the pectinate line. In the currently most popular technique the abdominal dissection is carried out down to the levator muscle, the rectum is severed at this level and the ileal pouch is connected to the rectal stump by a stapling device. In analogy to the traditional total proctocolectomy procedure, it has been considered a curative and cancer-prophylactic procedure since all diseased mucosae are completely removed. At first sight, restorative proctocolectomy therefore seems to be an unmistakable opportunity; however, recent results imply that the IPAA procedure may not be the panacea it was thought to be. It is a demanding operation with a high potential for complications even in an experienced surgeon's hands and the functional results are sometimes far from perfect [41]; even its place as a cancer-prophylactic procedure may in fact be in question. An increasing number of cancers have been reported in these patients and the incidence is expected to rise as the length of follow-up increases [42].

Chronic inflammation in the ileal mucosa (pouch-itis) is a frequent complication in continent ileosto-my and has proved subsequently to be so even in the pelvic pouch (IPAA)[43]. A case of adenocarcinoma in the continent ileostomy [44] and sporadic reports of dysplasia in the ileal pouch mucosa, have currently appeared in the literature, suggesting that the morphological transformation of the ileal pouch mucosa might eventually result in cellular dysplasia and eventually carcinoma [45, 46]. The atrophic colonlike mucosa in the ileal pouch is hypothetically considered a potentially premalignant condition with risk of subsequent development of advanced neo-plastic transformation. It has been suggested that dysplasia and aneuploidy, as demonstrated by these authors, reflect a different pathway of an atrophic mucosa-dysplasia carcinoma sequence. However, the results from long-term studies, both on continent ileostomy patients and subsequently on IPAA patients, are reassuring [47, 48]. The overall incidence of mucosal dysplasia in the ileal pouch mucosa proved to be low and no case of high-grade dysplasia or carcinoma was observed. Considering an observation time of an average of 30 years in these studies, and the comparatively large series of patients, these results imply that dysplastic and neoplastic transformation within the ileal pouch mucosa is extremely rare regardless of the type of adaptation and the risk for epithelial dysplasia in the ileal pouch mucosa to progress into cancer seems to be very low.

The published reports on cancer that develops in the IPAA patients operated on for ulcerative colitis, reflect a quite different issue, however [42, 48]. Irrespective of the technique used, IPAA leaves residual rectal mucosa behind and dysplasia in these rectal mucosal remnants with subsequent cancer development has proved to be a procedural risk, reflecting the continuous risk of malignant transformation in the chronically inflamed rectal mucosa. Thus, it has been demonstrated that even after a careful macro-scopically complete mucosectomy, islands of remnants of rectal mucosa are left behind in about 20% of the cases [49], and in the alternative technique where the ileal pouch is stapled to the top of the anal canal, varying amounts of rectal mucosa as well as the anal transitional zone mucosa remain preserved. The rectal stump may even include part of the lower rectum in technically demanding cases. Thus, there is a potential risk for malignant development in the islands of mucosa remaining between the muscular cuff and ileal mucosa or in the retained mucosa in the anal transitional zone, the so-called residual epithelial cuff after the stapled technique. Moreover, it is convincingly demonstrated that this risk is impending in patients with a long history of antecedent ulcerative colitis, and with the diagnosis of dysplasia or cancer in the operative specimen at the time of colectomy [42, 48]). Therefore, although there are reports suggesting that an IPAA is a successful surgical approach for ulcerative colitis patients with coexisting colorectal cancer [50], it is doubtful if such an approach should be recommended.

Although some colorectal surgeons may question the need for routine surveillance for cancer in the IPAA patients [51], these observations imply that despite the fact that the cancer risk after IPAA may well be less than after the IRA procedure, a similar endoscopy surveillance is still justified. A close follow-up in all IPAA patients should be emphasised, with special attention focussed on those with a long antecedent disease history and those with dysplasia or cancer in the original specimen. In this context, it should be emphasised that the dysplasia or early cancer that arises from the residual rectal tissue in the muscular cuff after mucosectomy may not be easily detectable and endoscopy surveillance with deep random biopsies of the anal canal mucosa should be recommended.

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