Qualitative assessment and morphometry in the study of the ileal reservoir after restorative proctocolectomy

Little is known about the long-term effects on the reservoir mucosa in patients with ulcerative colitis and familial polyposis coli who undergo proctocolectomy with subsequent construction of ileal reservoir/pouch and ileoanal anastomosis. In these patients, questions regarding adaptation towards a more colon-like mucosa and/or development of (pre)malignant changes are of particular importance. With the aim of designing a method for reliable evaluation of the mucosa in the ileal pouch, biopsies from 10 patients were studied by semiquantitative assessment and morphometry. The findings were compared with those obtained from normal jejunum, ileum, and colon. The following parameters were found to be important: Villous surface density, quantity of goblet cells, number of mitoses, and the presence/absence of predominantly sulphated mucin+ goblet cells. The number of Paneth cells did not show significant changes. The villous surface density was determined by a cycloid test system applied to vertical sections. Semiquantitative assessment was a sufficiently precise method for the evaluation of the quantity of goblet cells. The counting of sulphated mucin+ goblet cells was not reproducible, instead a simple statement about the presence or absence of these cells was judged to be adequate. The number of mitoses and of Paneth cells were counted directly. During the first year of function the ileal pouch showed signs of adaptation towards a colon-like mucosa: Reduction of villous surface density, increased mitotic activity, and appearance of sulphated mucin+ goblet cells. The number of Paneth cells did not show significant changes. The amount of goblet cells was generally not increased, rather reduced in some patients.