The use of colonoscopy solely for the detection of recurrences is limited because the majority of cancer recurrences are extraluminal. Nonetheless, colonoscopy is still important for the detection of metachronous lesions, even if there is no suspicion of cancer recurrence. Positron emission tomography/CT is the best way to detect widespread recurrences; however, locoregional tumor recurrence may occur after colorectal resection of a tumor. Commonly, recurrence starts extraluminally from metastatic nodules, regional lymph nodes, or the pelvic side walls. The recurrent tumor only eventually invades the intestinal lumen. The presence of an intact anastomotic line on endoscopy may be an indication that the recurrence is but a locoregional manifestation of a disseminated recurrence (Fig. 5.2). In this respect, previous anastomotic leakage is one of the risk factors for anastomotic recurrence [11, 21, 22]. Endoscopy and biopsies are necessary to confirm whether the lesion has indeed invaded the lumen and may be used concurrently with other imaging suggestive of locoregional recurrence.

Occasionally, local recurrence may start at the anastomotic line. This may be due to luminal implantation of viable shed or trapped cancer cells during the initial colorectal manipulation or anastomosis and is a not uncommon finding after transanal surgery or transanal endoscopic microsurgery procedures, particularly when performed for T2 lesions with mucinous or poor differentiation [23]. These occurrences direct many coloproctologists toward intraoperative cytocidal rectal washout before colorectal anastomosis [24]. Isolated colorectal anastomotic recurrence has a better prognosis than extraluminal recurrence, and detection of such cases in the absence of extraluminal disease is an indication for radical curative repeat resectional surgery. Occasionally, the “recurrent tumor” may be noted to be near but not at the anastomotic line. Such cases, coupled with no recurrence elsewhere as seen on extensive imaging, may indicate a metachronous cancer due to field change, and careful colonoscopy is, therefore, vital in deciding the most appropriate resection and extent of resection to be undertaken.

Endoscopy is one of many available tools used to evaluate structural abnormalities of these pouches, including pouch inlet and outlet strictures, pouch fistulas, and sinuses and leaks. The accuracy of endoscopy is enhanced by combining it with other methods of imaging, including CT enterography, gastrograffin enemas, and MRI [25]. A specific complication is a leak from the blind end of the “J” pouch, which may require ultrasound- or CT-guided drainage and catheter placement. Over time, when repeated radiology is needed in some patients, MRI will be favored over the radiation exposure of repeated CT. In this respect, CT enterography seems to have the lowest accuracy for the diagnosis of small-bowel strictures, inlet strictures, or both, whereas MRI has the lowest accuracy for pouch sinuses; combining these modalities with pouch endoscopy increases the overall diagnostic accuracy in these conditions. The main advantage of endoscopy over the other modalities is the ability to obtain tissue ­biopsies, where histological analysis may reveal a diagnosis of Crohn’s disease after a previous diagnosis of ulcerative colitis or show the presence of dysplastic mucosa after previous surgery for familial adenomatous polyposis. Endoscopic mucosal surveillance detects and grades pouchitis and monitors treatment, which has implications for the diagnosis of pouch failure and will help determine whether a pouch salvage procedure or pouch excision should be undertaken.

Anastomotic stricture after colorectal or coloanal anastomoses occurs in up to 30 % of patients [26–28]. Direct visualization with endoscopy allows the surgeon to determine the location, nature, length, and extent of the stricture as well as the opportunity for biopsy. Asymptomatic strictures discovered incidentally during radiological examination or endoscopically may not need intervention; a narrowed anastomosis in the early postoperative period normally dilates naturally with time. Symptomatic strictures, however, need further evaluation and treatment, as indicated by the symptoms or cause. Endoscopy permits balloon dilatation, which has been reported to be successful in up to 90–100 % of patients (Figs. 5.3, 5.4, and 5.5) [27, 29, 30], which may be supplemented by deployment of a self-expanding metallic stent. Recently, Forshaw et al. [31] have reported successful outcomes with endoscopic transanal stricture resection for the management of high-grade anastomotic strictures; there is a short length of hospital stay, although there is an incidence of reoperation for bleeding and reported microperforations, with technical difficulties with its use if the anastomosis is acutely angulated. Several endoscopic electrocision ­techniques have been described, also using a papillotomy or hook knife in combination with fluoroscopic identification of the proximal bowel, particularly if the original anastomosis is an end-to-side configuration [32–35]. In this regard, some techniques have been associated with a relatively high rate of restricturing [32].

Further alternatives have included endoscopic steroid injection of Crohn’s strictures, although single treatments do not reduce the time to repeat dilatation, and at least two injections are required in most cases [36]. More recently, ­biodegradable stents have been used, but there is no clear relationship between the number of dilatations required in combination with stenting and the incidence of symptomatic stricture recurrence [29, 37, 38]. In these patients, there is a greater self-reported incidence of gastrointestinal symptoms in patients undergoing dilatation, including frequent bowel movements, bloating, abdominal pain, and constipation or diarrhea, with an impaired reported health-related quality of life that is somewhat independent of the delay between stricture dilatation and the time of assessment [39]. This probably is representative of a disparity between radiological, endoscopic, and patient-related clinical symptoms in the definition of stricture severity and length.