Anorectal manometry (ARM) provides comprehensive information about the physiologic state of the anal sphincter and rectal sensation for evaluation of fecal incontinence or constipation. It is also used to examine patients with low anterior resection syndrome (LARS), which means fecal incontinence due to anorectal anatomical and physiological changes occurring after a low anterior resection (LAR) for rectal cancer [1,2]. As the frequency of sphincter-saving procedures has increased due to technical developments in rectal cancer surgery, the incidence of LARS and the use of ARM have also increased. ARM is generally regarded as a safe procedure, and the literatures evaluating manometry-induced colon perforation and its management is lacking. Although a few cases have been reported, most of them were accompanied by complications or death. We successfully treated three patients experiencing manometry-induced colon perforation with fecal peritonitis without any complications by using prompt and active operations, and we report those cases so as to provide information on the principles and the general course of management for patients experiencing manometry-induced colon perforation.

An iatrogenic colorectal perforation related to ARM is a rare complication. Park et al. [3] reported 2 cases; 1 patient who had undergone a LAR improved after only conservative treatment, but the other who had undergone a LAR following preoperative chemoradiotherapy died immediately after the emergency surgery. Jeong et al. [4] reported 1 case, in which the patient had undergone a LAR following preoperative chemoradiotherapy and was treated by surgery after failure of conservative treatment resulting in colo-cutaneous fistula with abdominal fasciitis. Both authors suggested that manometry should be performed with great care. Park et al. [3] also insisted that the maximum tolerable volume should not be routinely measured for patients who had undergone a restorative proctectomy. In our institute, we perform ARM (Orion Platinum K003367, SRS Medical Systems, Billerica, MA, USA) on patients who present with severe LARS, who are intractable to loperamide, and whose qualities of life are markedly disturbed. Some of those patients are treated with biofeedback therapy. The ARM was initially performed by a colorectal surgeon, but it is now performed by a special nurse of the Outpatient Department, who has several years of recent experience with colorectal surgery. The resting and squeezing pressures are measured by using the stationary and continuous pull-through method and a sensory threshold test including first sensation, desire-to-defecate sensation, and maximal sensation. If the post-LAR patient cannot feel the maximal sensation even after 100 mL of saline is injected into the balloon or the patient complains of anal discomfort or pain, the examination is discontinued. In our cases, the first patient had undergone pelvic irradiation for prostate cancer. He also had chronic constipation combined with fecal incontinence after LAR. Therefore, the rectal wall of this patient was considered to be vulnerable and inelastic because of radiation injury and potential stercoral ulceration. The second patient had also undergone radiotherapy and a LAR. He also underwent manometry 3 months after the surgery. The neorectum was also considered to be vulnerable and inelastic due to radiation injury. The third patient had undergone only a LAR without radiotherapy. However, because the timing of manometry was relatively early, 2 months after the LAR, the neorectum was considered as vulnerable.

In the treatment of an iatrogenic colonic perforation, nonoperative management of the colonic perforation is advocated for patients who are clinically stable and present no evidence of peritonitis [5]. For selected patients with incidental intramural or small retroperitoneal perforations but no evidence of fecal spillage, favorable results have also been reported as the result of conservative treatment consisting of bowel rest combined with total parenteral nutrition, intravenous fluid treatment, and administration of broad-spectrum antibiotics [6]. Especially, when the colonic perforation occurs during a colonoscopy, the bowel content in the colon is minimal because of the bowel preparation, and colonic tissue is generally healthy. Therefore, laparoscopic primary repair or even conservative treatment can be considered [7]. As in the case of colonoscopy-induced colon perforation, in the case of ARM-induced colon perforation, if spillage of bowel content is minimal and the perforation occurs in the mesenteric space, the subsequent symptoms of the patient are usually tolerable, so primary repair or conservative treatment can be considered. However, when a colon perforation occurs after ARM in patients with LARS, the defect is likely to be relatively large; consequently, the fecal spillage tends to be extensive for 2 reasons. First, because their neorectums are relatively vulnerable and inelastic due to postoperative change or radiation injury, the defect is not small, so natural healing is difficult to expect in many cases. Furthermore, an underlying stercoral ulcer due to prolonged intake of loperamide may be present. Second, their neorectums are generally filled with fecal material due to inharmonic defecation in spite of the fecal incontinence associated with LARS. Overflow incontinence related to constipation due to prolonged intake of loperamide may be considerable.

As a result of our experience, especially with these 3 cases, we suggest that ARM with a balloon, as a measure of rectal compliance, be performed two or more months after the surgery. Especially, caution during ballooning is mandatory for irradiated patients regardless of when the examination is performed, even if it is performed several years after the surgery. Also, when a patient with LARS complains of discomfort or pain, especially of the abdomen, a cessation of the examination followed by close observation should be considered. When a perforation occurs, prompt and active surgical intervention is necessary due to high possibility of extensive fecal peritonitis.