POUCHITIS - WHATS NEW IN ETIOLOGY AND MANAGEMENT

Pouchitis requires a clear clinicopathological definition. There are m any conflicting data concerning etiology. It is linked to an initial d iagnosis of ulcerative colitis by clinical association and occurrence of extra-alimentary manifestations, histologically and by macrophage t ypes and inflammatory mediators. Evidence for a bacteriological cause comes from response to metronidazole, increased counts of intramucosal bacteria in pouchitis and the possible association of hypochlorhydria . Most studies have, however, shown no specific bacterial pathogen or luminal bacterial count differences in pouches with or without pouchit is. Abnormal fecal bile salt concentrations have been reported. Stasis and evacuation efficiency of the pouch are not associated with pouchi tis in most studies. Reduced mucosal bloodflow may be associated perha ps leading to increased permeability to toxins causing activation of i nterleukin-1, platelet-activating factor (PAF) and tumour necrosis fac tor (TNF). PAF may be increased in pouchitis. Pouchitis may respond to allopurinol. Volatile short chain fatty acids (VSFA) may be reduced i n ileal reserviors compared with straight ileoanal segments and in pou chitis. The response of pouchitis to administered VSFA is, however, va riable. Glutamine administration may help. There is evidence that intr aepithelial T lymphocytes are reduced. Crypt cell turnover is higher i n colitic than in polypotic pouches. Mucosal morphological changes of villous atrophy and inflammation occur early after relapsing polychond ritis and may predict future susceptibility to pouchitis. Early mucosa l biopsy appears to have prognostic value. Metronidazole and antibioti cs (amoxicillin/potassium clavulanate, ciprofloxacin) may be effective although in a controlled trial of the former there was little advanta ge over placebo. The results of treatment using VSFA, glutamine, allop urinol sucralfate and anti-inflammatory agents, including aminosalicyc lic acid (5-ASA) and steroids, is reviewed. Assessment of efficacy is difficult because the definition of pouchitis is not standardized, the re may be more than one clinical type and studies may not be controlle d. Failure of medical treatment may require surgical defunctioning or removal of the pouch.