Restorative proctocolectomy: histological assessment and cytometric DNA analysis of ileal pouch biopsies

The pathological changes and the risk of developing cancer in the ileal pouch mucosa of patients who received restorative proctocolectomy with ileal pouch-anal anastomosis (IPAA) were studied. The presence or absence of remaining rectal mucosa below the IPAA in both patients with stapled and handsewn IPAA was also examined.

Endoscopy of the ileal pouch was performed on 38 patients at 4, 12, 18 and 36 months after restorative proctocolectomy with ileal pouch. Mucosal biopsy specimens were taken from the ileal reservoir in order to assess the histological incidence of inflammation. In 23 patients, biopsies were taken to perform cytometric DNA analysis. Clinical symptoms of pouchitis (over six evacuations in 24 hours, night-time evacuations, leakage of feces, bloody diarrhea, abdominal pain and fever) were recorded and correlated with the histological findings. Biopsies were also sampled below the ileo-anal anastomosis (IPAA) in order to identify residual rectal mucosa.

Results of histological assessment showed various degrees of chronic inflammation increasing over time (from 42 to 60%) while the presence of both acute and chronic inflammation of the reservoir was less frequent (from 18 to 30%). Villous atrophy was present in 39-68% of patients and the grade of villous atrophy was correlated to the grade of inflammation. Clinical pouchitis was present in 3 to 8% of cases at the different controls and it was always associated with the highest grade of histological inflammation and severe villous atrophy. No significant alteration of the DNA cellular content was observed. Very low incidence of aneuploidy (0.7-1% Ex.R.) has been reported in three cases. However, we found dysplasia in only one patient who underwent surgical treatment for familial polyposis coli. IPAA evaluation showed no residual rectal mucosa in 40% of cases with stapled IPAA; in the remaining 60%, we found a small amount of rectal mucosa (maximum 1 cm). We did not find rectal mucosa after handsewn IPAA with mucosectomy.

Patients treated with restorative proctocolectomy with IPAA showed a higher and increased incidence of inflammation during follow-up. No significant alteration of DNA cellular content nor dysplasia of the pouch mucosa were observed. In this study the chance of leaving rectal mucosa after stapled IPAA was about 60%.