Uncovering Preoperative Characteristics Linked to Crohn’s Disease of the Pouch Post-IPAA

Photo Credit: Panuwat Dangsungnoen

Patients who develop CDP after IPAA often face significantly lower QOL with a higher risk of septic complications and pouch failure.

According to a team of researchers led by Michael Fadel, NIHR Doctoral Fellow, “following ileal pouch-anal anastomosis (IPAA) for ulcerative colitis (UC), up to 16% of patients develop Crohn’s disease (CD) of the pouch (CDP), which is a major cause of pouch failure.” They posted their findings online in the Journal of Crohn’s and Colitis.

“Despite advances in the medical treatment of UC, up to 35% of patients with UC will ultimately require colectomy,” they explained. “It has been reported that 5%–16% of UC patients undergoing total proctocolectomy and IPAA subsequently develop clinical, radiological, endoscopic or histopathological findings of CD described as CDP or Crohn’s-like disease of the pouch.”

Understanding the Risk

The researchers aimed to identify preoperative characteristics and risk factors for CDP following IPAA for UC. They conducted a systematic review and meta-analysis of seven studies with 1,274 patients. The study team found that patients with CDP were more likely to have a younger age at UC diagnosis and pouch surgery, a shorter duration of UC, a family history of inflammatory bowel disease (IBD), and a history of smoking. Dysplasia or cancer of the colon as an indication for pouch surgery was found to be a protective factor against CDP. Other factors such as Ashkenazi heritage, female gender, primary sclerosing cholangitis (PSC), and family history of CD were not associated with CDP. The study found that age at UC diagnosis and pouch surgery, family history of IBD, and previous smoking are potential risk factors for CDP post-IPAA. These findings have important implications for preoperative counseling, surgical management, and prognosis evaluation.

“The development of CDP after IPAA is associated with a significantly lower quality of life and higher risk of septic complications and pouch failure, resulting in pouch resection or permanent diversion,” said Dr. Fadel and colleagues. “Therefore, the identification of risk factors for CDP is becoming an increasingly important component of preoperative surgical planning, evaluation of prognosis and postoperative management.”

The study also highlighted challenges in diagnosing CDP, with significant variation in the definition in the literature. The consensus guidelines from the International Ileal Pouch Consortium emphasized the importance of reaching an agreement on the terminology and diagnostic criteria of CDP.

The findings of the study suggested that CDP may develop from variable settings, such as those with a preoperative diagnosis of CD and development of de novo disease after colectomy.

Lowering the Risk of CDP Following IPAA

The most reported diagnostic criteria were the presence of fistula, stricture of the pouch or pre-pouch ileum, or pre-pouch ileitis. The researcher also considered the presence of non-caseating, non-crypt rupture-associated granulomas in the afferent limb, pouch body, or cuff biopsy highly suggestive but not required for diagnosing CDP. The study authors said that the development of CDP following IPAA adversely affects patient outcomes and prognosis, with patients often requiring aggressive therapy and potential excision of the pouch with the formation of a permanent end ileostomy.

Dr. Fadel and his team also discussed the potential mechanisms of CDP following IPAA, including changes in bacterial flora, underlying genetic susceptibility, and the non-physiological environment created in the terminal ileum. Their study highlighted the need for further research to better understand the mechanisms and risk factors associated with CDP and the development of standardized diagnostic criteria.

Overall, they concluded that the identification of risk factors for CDP is becoming increasingly important for preoperative surgical planning, prognosis evaluation, and postoperative management.

“These factors need to be taken into consideration with preoperative counselling, planning surgical management and monitoring patients postoperatively to reduce the risk of pouch failure, the authors concluded. “Patients should be counseled that if they develop a stricture or stenosis, then their pouches may fail as a result, which may be secondary to CDP.”