Persistent Pain After Colonic Endoscopic Mucosal Resection: Predictors, a Management Algorithm and Outcomes

Large, sessile, colonic polyps of ≥ 20 mm are at increased risk of progressing to colorectal cancer (CRC). Most colonic polyps are small and pedunculated and can be safely removed by conventional polypectomy. Treatment of large polyps however, is challenging but very important in preventing development of CRC, the second leading cause of cancer deaths worldwide. Early detection and treatment of these polyps, possible through vigilant CRC screening via colonoscopy, shows significant reduction in incidence of CRC.

Over the last decade, endoscopic mucosal resection (EMR) has been recognised as a safe and reliable alternative to surgery to remove large, sessile colonic polyps of ≥ 20mm. The benefits of EMR over traditional surgery include reduced risk of peri- and post-operative complications from surgery (particularly in elderly patients with multiple co-morbidities), less health expenditure and reduced length of hospital admission. The majority of patients can be managed safely as outpatients post EMR.

EMR has been proven to be a safer alternative to traditional surgery, but is a technically challenging procedure. The most common complication post procedure is non-specific abdominal pain, which occurs in 10-20% of cases. The cause is often innocent such as simple luminal distension during the procedure. The advent of improved EMR techniques, for example using carbon dioxide instead of air insufflation, significantly reduces incidence of abdominal pain and subsequently need for admission.

Colonic perforation during colonoscopy rates range from 0.06 to 0.1%. Advanced age, female gender, having a colonoscopy indication of abdominal pain or Crohn's disease, result in a statistically higher risk of colonic perforation. In addition, ICU inpatients have substantially greater odds of perforation. A recent study, conducted over twelve years in a total of 110,785 patients undergoing diagnostic and therapeutic colonoscopies, showed one case of colonic perforation associated with EMR.

Currently, it remains difficult to delineate innocent abdominal pain from more serious complications. There are no standard algorithms used in clinical practice to stratify risk post EMR according to patient's symptoms and there are no data supporting previously proposed pain algorithms. There is also a paucity of data regarding pain scales employed in the past to show significant correlation between pain level and risk of perforation or bleeding. The 100mm Visual Analog Scale (VAS) has been documented to have sound correlation in patients presenting to the emergency department with an acute abdomen and could be a useful aid in a formal assessment based on pain post EMR.