Mucosal morphology, cell proliferation and faecal bacteriology in acute pouchitis

The aetiology of pouchitis in patients with inflammatory bowel disease

Restorative proctocolectomy with ileal pouch-anal anastomosis is a treatment option for patients with refractory ulcerative colitis. Pouchitis is the most common complication, representing a spectrum of diseases ranging from acute antibiotic-responsive type to chronic antibiotic-refractory. Early accurate diagnosis using a combined assessment of symptoms, endoscopy and histology is important for both treatment and prognostication. Most patients respond well to antibiotic therapy; however, management of chronic antibiotic-refractory pouchitis remains a challenge, and treatment options are based on small studies. Pouchitis is thought to be driven by the interaction between genetics, the immune system and the environment but as yet a causal relationship has yet to be identified. Further longitudinal assessment of the pouch integrating new technologies may help us understand the factors driving pouchitis. This review outlines the currently understood risk factors and aetiology of pouchitis.

Association of colonic metaplasia of goblet cells and endoscopic phenotypes of the J pouch in patients with ulcerative colitis: a retrospective pilot study

BACKGROUND/AIMS

Mucosal adaptation of the ileum toward colonic epithelium has been reported in pouchitis in ulcerative colitis (UC); however, the clinical characteristics, endoscopic findings, and outcomes in patients with pouchitis with ileal mucosal adaptation are poorly understood.

METHODS

This was a single-center retrospective study comprising UC patients treated by proctocolectomy with ileal pouch-anal anastomosis who had undergone pouchoscopy at the University of Tsukuba Hospital between 2005 and 2022. Endoscopic phenotypes were evaluated according to the Chicago classification. High-iron diamine staining (HID) was performed to identify sulfomucin (colon-type mucin)-producing goblet cells (GCs) in pouch biopsies. We compared clinical data between patients with (high HID group) and without > 10% sulfomucin-producing GCs in at least one biopsy (low HID group).

RESULTS

We reviewed 390 endoscopic examination reports from 50 patients. Focal inflammation was the most common phenotype (78%). Five patients (10%) required diverting ileostomy. Diffuse inflammation and fistula were significant risk factors for diverting ileostomy. The median proportion of sulfomucin-producing GCs on histological analysis of 82 pouch biopsies from 23 patients was 9.9% (range, 0%-93%). The duration of disease was significantly greater in the high HID group compared to the low HID group. The median percentage of sulfomucin-producing GCs was significantly higher in patients with diffuse inflammation or fistula compared to other endoscopic phenotypes (14% vs. 6.0%, P= 0.011).

CONCLUSIONS

Greater proportions of sulfomucin-producing GCs were observed in endoscopic phenotypes associated with poor outcomes in UC, indicating patients with pouchitis showing colonic metaplasia of GCs may benefit from early interventions.

Gut Microbiota Composition Changes in Constipated Women of Reproductive Age

Background

Chronic constipation is one of the most prevalent functional gastrointestinal disorders, yet its etiology is multifactorial, and the pathophysiological mechanism is still unclear. Previous studies have shown that the gut microbiota of constipated patients differs from healthy controls; however, many discrepancies exist in the findings, and no clear link has been confirmed between chronic constipation and changes in the gut microbiota. Growing evidence indicates that age, gender, and hormone levels can affect the composition of gut microbiota. The aim of this study is to examine the overall changes in gut microbiota within a specific sub-population of patients, namely, constipated women of reproductive age.

Methods

We carried out a cross-sectional study comparing the fecal microbial composition of 30 healthy women and 29 constipated women using 16S rRNA gene sequencing. Only women of reproductive age were recruited to reduce the effects of age, gender, and hormone levels on the microbiome, and to prevent conflating the impact of these factors with the effects of constipation.

Results

There were obvious differences in the gut microbiota in constipated women of reproductive age compared with the healthy controls, manifesting mainly as a significant increase in the abundance of Bacteroides (p < 0.05) and a significant decrease in the abundance of Proteobacteria (p < 0.01). The overall composition of the gut microbiota in each group was different, which was reflected in the ratios of Firmicutes to Bacteroidetes (F/B), which was 1.52 in the constipated group vs. 2.21 in the healthy group. Additionally, there was a significant decrease in butyrate-producing bacteria, like Roseburia and Fusicatenibacter (p < 0.01).

Conclusion

The overall composition of the gut microbiota changed in constipated women of reproductive age, characterized by a loss in Proteobacteria and an increase in Bacteroidetes. Furthermore, the abundance of some butyrate-producing bacteria also reduced. These changes may reflect the unique interactions between host and some bacteria, or some bacterial metabolic products, which may be important targets for future studies to explore the pathogenesis of constipation.

Histopathological evaluation and risk factors related to the development of pouchitis in patients with ileal pouches for ulcerative colitis

OBJECTIVE

Many changes in mucosal morphology are observed following ileal pouch construction, including colonic metaplasia and dysplasia. Additionally, one rare but potential complication is the development of adenocarcinoma of the reservoir. The aim of this study was to evaluate the most frequently observed histopathological changes in ileal pouches and to correlate these changes with potential risk factors for complications.

METHODS

A total of 41 patients were enrolled in the study and divided into the following three groups: a non-pouchitis group (group 1) (n = 20; 8 males; mean age: 47.5 years) demonstrating optimal outcome; a pouchitis without antibiotics group (group 2) (n = 14; 4 males; mean age: 47 years), containing individuals with pouchitis who did not receive treatment with antibiotics; and a pouchitis plus antibiotics group (group 3) (n = 7; 3 males; mean age: 41 years), containing those patients with pouchitis who were administered antibiotics. Ileal pouch endoscopy was performed, and tissue biopsy samples were collected for histopathological analysis.

RESULTS

Colonic metaplasia was found in 15 (36.6%) of the 41 patients evaluated; of these, five (25%) were from group 1, eight (57.1%) were from group 2, and two (28.6%) were from group 3. However, no correlation was established between the presence of metaplasia and pouchitis (p = 0.17). and no differences in mucosal atrophy or the degree of chronic or acute inflammation were observed between groups 1, 2, and 3 (p>0.45). Moreover, no dysplasia or neoplastic changes were detected. However, the degree of mucosal atrophy correlated well with the time of postoperative follow-up (p = 0.05).

CONCLUSIONS

The degree of mucosal atrophy, the presence of colonic metaplasia, and the degree of acute or chronic inflammation do not appear to constitute risk factors for the development of pouchitis. Moreover, we observed that longer postoperative follow-up times were associated with greater degrees of mucosal atrophy.

A meta-analysis of probiotic efficacy for gastrointestinal diseases

Background

Meta-analyses on the effects of probiotics on specific gastrointestinal diseases have generally shown positive effects on disease prevention and treatment; however, the relative efficacy of probiotic use for treatment and prevention across different gastrointestinal diseases, with differing etiology and mechanisms of action, has not been addressed.

Methods/Principal Findings

We included randomized controlled trials in humans that used a specified probiotic in the treatment or prevention of Pouchitis, Infectious diarrhea, Irritable Bowel Syndrome, Helicobacter pylori, Clostridium difficile Disease, Antibiotic Associated Diarrhea, Traveler's Diarrhea, or Necrotizing Enterocolitis. Random effects models were used to evaluate efficacy as pooled relative risks across the eight diseases as well as across probiotic species, single vs. multiple species, patient ages, dosages, and length of treatment. Probiotics had a positive significant effect across all eight gastrointestinal diseases with a relative risk of 0.58 (95% (CI) 0.51–0.65). Six of the eight diseases: Pouchitis, Infectious diarrhea, Irritable Bowel Syndrome, Helicobacter pylori, Clostridium difficile Disease, and Antibiotic Associated Diarrhea, showed positive significant effects. Traveler's Diarrhea and Necrotizing Enterocolitis did not show significant effects of probiotcs. Of the 11 species and species mixtures, all showed positive significant effects except for Lactobacillus acidophilus, Lactobacillus plantarum, and Bifidobacterium infantis. Across all diseases and probiotic species, positive significant effects of probiotics were observed for all age groups, single vs. multiple species, and treatment lengths.

Conclusions/Significance

Probiotics are generally beneficial in treatment and prevention of gastrointestinal diseases. Efficacy was not observed for Traveler's Diarrhea or Necrotizing Enterocolitis or for the probiotic species L. acidophilus, L. plantarum, and B. infantis. When choosing to use probiotics in the treatment or prevention of gastrointestinal disease, the type of disease and probiotic species (strain) are the most important factors to take into consideration.

Surgical prophylaxis of pouchitis in ulcerative colitis

Ileal pouch-anal anastomosis (IPAA) is now the procedure of choice for most patients requiring proctocolectomy for ulcerative colitis. The J-shaped pouch, usually 15-20 cm in length, is easiest to construct and has functional outcomes identical to those of the more complex designs. IPAA is a complex procedure, and complications occur frequently. Despite the significant improvements this surgical advance has made on the quality of life in these patients, inflammation of the surgically created ileal pouch or pouchitis remains a major late postoperative complication that can often overshadow the benefits of this otherwise curative operation. Several inflammatory and noninflammatory complications can occur after IPAA. Pouchitis is the most common, occurring in ≈50% of patients. Whereas acute pouchitis can be treated rapidly and successfully in the majority of patients, refractory and chronic pouchitis remain therapeutic challenges to patients and physicians. The problem is believed to be caused by stasis of feces in the pouch with overgrowth of aerobic and anaerobic organisms. The size of the pouch has a significant influence on the incidence of pouchitis: a smaller pouch usually empties better than a larger pouch and so may be less susceptible to pouchitis.

The bacterial pathogenesis and treatment of pouchitis

Restorative proctocolectomy (RPC) with ileal pouch-anal anastomosis is the operation of choice for patients with ulcerative colitis. Pouchitis is the most common cause of pouch dysfunction. Although the pathogenesis of this disease is not well understood, bacteria have been implicated in the disease process. Numerous bacterial studies have been reported over the last 25 years with few unifying findings. In addition, many different treatments for pouchitis have been reported with varying results. Antibiotic treatment remains the most studied and is the mainstay of treatment. In this article we review the aetiology of pouchitis and the evidenced-based treatment options.

Bacterial community diversity in cultures derived from healthy and inflamed ileal pouches after restorative proctocolectomy

BACKGROUND

Pouchitis is believed to occur as a reaction to dysbiosis. In this study we assessed differences between mucosal bacterial communities cultured from noninflamed and inflamed ileal pouches.

METHODS

Thirty-two ileal pouch patients, 22 with ulcerative colitis (UC) and 10 with familial adenomatous polyposis (FAP), underwent symptomatic, endoscopic, and histological assessment. The Objective Pouchitis Score (OPS) and the Pouch Disease Activity Index (PDAI) were used to diagnose pouchitis. Seven UC patients had pouchitis (UC+), 15 had a noninflamed pouch (UC-), 9 had a noninflamed pouch (FAP-), and 1 FAP patient had pouchitis (FAP+). Biopsies taken from the ileal mucosa of the pouch were cultured under aerobic and anaerobic conditions. Following standardized DNA extraction a polymerase chain reaction (PCR) was performed to generate 16S rRNA gene products. A "fingerprint" of the bacterial community within each sample was created using terminal-restriction fragment length polymorphism (T-RFLP) profiling. Species richness and evenness were determined using T-RF band lengths and relative band intensities.

RESULTS

From the 64 DNA samples, 834 bands were detected, of which 179 represented different species (operational taxonomic units [OTUs]). The average species richness for the FAP-, FAP+, UC-, and UC+ groups was 26, 35, 23.9, and 29.6 per patient, with the average species diversity within the groups of 10.6, 29, 8.3, and 11.4, respectively. Similar trends were observed when the anaerobic and aerobic-derived bacterial groups were analyzed separately.

CONCLUSIONS

No significant differences were found between the bacterial cultures derived from any of the clinical groups or between pouchitis and nonpouchitis patients.

Pros and cons of antibiotic therapy for pouchitis

Restorative proctocolectomy with ileal pouch-anal anastomosis has become the surgical treatment of choice for patients with medically refractory ulcerative colitis or ulcerative colitis with dysplasia and for the majority of patients with familial adenomatous polyposis. However, pouchitis and other pouch-associated complications frequently occur following surgery. Pouchitis is the most common long-term complication of ileal pouch-anal anastomosis in patients with ulcerative colitis, with a cumulative prevalence of up to 50%. The pathogenesis of pouchitis is probably associated with alterations in commensal bacterial flora, and most patients with pouchitis respond favorably to antibiotic therapy. Antibiotic therapy is the mainstay of treatment for active pouchitis, with ciprofloxacin or metronidazole traditionally being first-line agents. Some patients may develop dependency on antibiotics, thus requiring long-term maintenance therapy. In a subset of patients, the disease course may be refractory to antibiotic therapy, which is one of the common causes of pouch failure, requiring permanent ileostomy or pouch excision. On the other hand, long-term antibiotic use is expensive and can be associated with adverse effects and bacterial resistance. There may also be the risk of secondary infections, such as Clostridium difficile and fungal infections. The risks and benefits should be carefully balanced in patients who require long-term antibiotic therapy, and safe, efficacious, non-antibiotic-based agents are needed.

The efficacy and tolerability of AST-120 (spherical carbon adsorbent) in active pouchitis

OBJECTIVES

Although a majority of patients with pouchitis respond favorably to antibiotic therapy, many relapse frequently, and nonabsorbable and non-antibiotic-based agents are desirable for reducing bacterial resistance and the systemic adverse effects associated with long-term antibiotic exposure. AST-120 (a spherical carbon adsorbent) comprises highly adsorptive, porous carbon microspheres with the ability to adsorb small-molecular-weight toxins, inflammatory mediators,and harmful bile acids. The aim of this pilot trial was to evaluate the efficacy and tolerability of AST-120 in the treatment of active pouchitis.

METHODS

Eligible patients were recruited from two subspecialty pouchitis clinics. Inclusion criteria were(i) ileal pouch-anal anastomosis performed for ulcerative colitis; (ii) active pouchitis with Pouchitis Disease Activity Index (PDAI) scores > or =7; and (iii) discontinuation of antibiotic therapy for at least 2 weeks. Exclusion criteria included Crohn's disease of the pouch, isolated cuffitis, pouch strictures, abscess, and sinuses. All eligible patients received AST-120 in 2-g sachets (oral) open label, thrice a day for 4 weeks. The primary efficacy end point was remission as defined by a PDAI score of < 7 points; the main secondary end point was clinical response, defined by a reduction of the PDAI score of > or =3 points.

RESULTS

Nineteen of 20 patients completed the trial. Eleven patients (55.0 % ) had a clinical response to the therapy and 10 patients (50.0 % ) entered remission. Median reduction in the PDAI symptom, endoscopy, and histology subscores, and PDAI total scores after 4 weeks were -2( P = 0.002), -2 ( P = 0.003), 0 ( P = 0.32), and -4 ( P = 0.001) points, respectively. The agent was well tolerated; one patient experienced transient mild elevation of alkaline phosphatase of uncertain significance and one patient experienced an upper respiratory infection after taking one dose of AST-120 and was excluded from the fi nal analysis for the calculation of pre- and post-trial PDAI scores.

CONCLUSIONS

AST-120 seems to be effective and well tolerated in treating patients with active pouchitis.A randomized, placebo-controlled trial is warranted for assessing the long-term efficacy and safety of AST-120 in the disease.

Benefit of antibiotic therapy on pouchitis after ileal pouch anal anastomosis: A systematic review and meta-analysis of clinical trials

The aim of the study was to evaluate and collect current evidence on the effect of antibiotics in pretreatment of pouchitis after restorative ileal pouch anal anastomosis (IPAA). Pubmed, Embase, Web of Science, Scopus, and Cochrane Library databases were searched between 1966 and July 2008; and relevant clinical trials extracted, reviewed, and validated according to the study protocol. The outcome of interest was clinical improvement after treatment. Nine randomized, placebo-controlled clinical trials were found relevant and studied but 3 of them with 70 patients were entered into meta-analysis. Pooling of the results from these trials yielded an odds ratio of 15.96 with a 95% CI of 4.20–60.70, indicating a significant OR (p<0.0001) in treatment group in comparison to the placebo group. In conclusion, the meta-analysis confirms benefit of antibiotics in management of pouchitis after IPAA operation.

Pathogenesis of and unifying hypothesis for idiopathic pouchitis

Ileal pouch-anal anastomosis is the procedure of choice in the surgical management of refractory ulcerative colitis. Pouchitis affects up to 60% of patients following ileal pouch-anal anastomosis for ulcerative colitis. It overlaps significantly with ulcerative colitis such that improvements in our understanding of one will impact considerably on the other. The symptoms are distressing and impinge significantly on patients' quality of life. Despite 30 years of scientific and clinical investigation, the pathogenesis of pouchitis is unknown; however, recent advances in molecular and cell biology make a synergistic hypothesis possible. This hypothesis links interaction between epithelial metaplasia, changes in luminal bacteria (in particular sulfate-reducing bacteria), and altered mucosal immunity. Specifically, colonic metaplasia supports colonization by sulfate-reducing bacteria that produce hydrogen sulfide. This causes mucosal depletion and subsequent inflammation. Although in most cases antibiotics lead to bacterial clearance and symptom resolution, immunogenetic subpopulations can develop a chronic refractory variant of pouchitis. The aims of this paper are to discuss proposed pathogenic mechanisms and to describe a novel mechanism that combines many hypotheses and explains several aspects of pouchitis. The implications for the management of both pouchitis and ulcerative colitis are discussed.

Pouchitis: an evolving clinical enigma--a review

While the overall incidence of pouchitis is low, extensive research continues at clinical and experimental levels in attempts to unravel its etiology. The ileal pouch and pouchitis together represent a unique in vivo opportunity to study mucosal adaptation and inflammation in depth. In the recent past, molecular data relating to pouchitis has significantly expanded. These data provide invaluable insight into intracellular and extracellular events that underpin mucosal adaptation and inflammation. Advances in classification, risk factor evaluation, and prevention have meant that a review of this data, as well as its relationship to our current understanding of pouchitis, is both timely and warranted. Therefore, the aim of this review is to summarize recent data in the context of the established literature.

On the benefit of probiotics in the management of pouchitis in patients underwent ileal pouch anal anastomosis: a meta-analysis of controlled clinical trials

The objective of this study was to evaluate and collect current evidence on the effect of probiotics in preventing pouchitis after restorative ileal pouch anal anastomosis (IPAA). The Pubmed, Medline, EMbase, CINAHL, Web of Science, and Scopus bibliographic, and Google Scholar databases were searched between 1966 and May 2007, and relevant controlled clinical trials were extracted, reviewed, and validated according to the study protocol. The outcome of interest was for pouchitis defined by a pouchitis disease activity index (PDAI) > or =7. Five randomized, placebo-controlled clinical trials were included in the meta-analysis. Pooling of the results from these trials yielded an odds ratio (OR) of 0.04 with a 95% CI of 0.01-0.14 (P < 0.0001) in the treatment group in comparison with the placebo group. In conclusion, the benefit of probiotics in the management of pouchitis after IPAA operation was confirmed by the meta-analysis.

Sulphomucin expression in ileal pouches: emerging differences between ulcerative colitis and familial adenomatous polyposis pouches

PURPOSE

We characterized the expression of sialomucin and sulphomucin in pouches fashioned for familial adenomatous polyposis and ulcerative colitis. We correlated sulphomucin expression with bacterial colonization and mucosal inflammation.

METHODS

Ethical approval and informed consent were obtained. Mucosal biopsies from 9 patients with familial adenomatous polyposis and 12 with ulcerative colitis were obtained. Sulphomucin levels were assessed by using the high iron-diamine stain. Mucous gel layer composition was correlated with villous height, crypt depth, and total mucosal thickness. Mucous gel layer composition was correlated with acute and chronic inflammatory infiltrates. Colonization by a panel of seven bacterial species (including sulphate reducing bacteria) was established and correlated with sulphomucin levels.

RESULTS

High-iron-diamine positivity (i.e., sulphomucin expression) was greater in ulcerative colitis pouch mucous gel (2.083 +/- 0.5 vs. 0.556 +/- 0.4, P = 0.003). Sulphomucin expression correlated with reduced crypt depth, villous height, and total mucosal thickness. In the ulcerative colitis group, chronic inflammatory infiltrate scores were significantly greater for high-iron-diamine-positive patients. Colonization by sulphate reducing bacteria was increased in high-iron-diamine-positive patients.

CONCLUSIONS

Sulphomucin expression is increased in the mucous gel layer of the ulcerative colitis pouch compared with that of the familial adenomatous polyposis pouch. Sulphomucin expression is associated with colonization by sulphate-reducing bacteria and increased chronic inflammation.

Use of a monoclonal antibody to sucrase-isomaltase for evaluation of the columnar cuff after stapled restorative proctocolectomy

PURPOSE

Restorative proctocolectomy with a double-stapled pouch-anal anastomosis retains a cuff of diseased columnar mucosa (columnar cuff) in the upper anal canal that may require biopsy. Biopsying this can be difficult and colonic phenotypic change in the pouch can lead to errors interpreting the histology. This study was designed to investigate the use of a monoclonal antibody to sucrase-isomaltase for differentiating ileal pouch from columnar cuff mucosa. Then, by using this antibody, the ability to accurately take and report biopsies from the anal canal was examined.

METHODS

The technique of staining for sucrase-isomaltase was developed. From 113 patients who had a double-stapled pouch-anal anastomosis, 467 formalin-fixed biopsies and 177 fresh-frozen biopsies were taken from the ileal pouch, columnar cuff, or anal transitional zone. Biopsies were stained with a monoclonal antibody to sucrase-isomaltase, and fixed biopsies were routinely reported after staining with hematoxylin and eosin.

RESULTS

A monoclonal antibody to sucrase-isomaltase reliably discriminated between ileal from rectal mucosa. A biopsy of columnar cuff mucosa as reported by routine histology was obtained during 72 percent of attempted outpatient examinations. Sucrase-isomaltase staining of reported columnar cuff biopsies showed that biopsies were of pouch rather than columnar cuff in 4.4 percent (95 percent confidence interval, 2-8) of outpatient examinations.

CONCLUSIONS

The monoclonal antibody to sucrase-isomaltase used in this study may have a clinical role when interpreting columnar cuff biopsies from patients being investigated for pouch dysfunction, or in patients having surveillance biopsies to exclude neoplasia in the columnar cuff.

Vascular endothelial growth factor and cyclooxygenase-2 are overexpressed in ileal pouch-anal anastomosis

PURPOSE

Pathophysiology of pouchitis after ileal pouch-anal anastomosis is controversial because of the potential for development of carcinoma. Cyclooxygenase-2-derived prostaglandins may be involved in the inflammatory process and play a role in the pathogenesis of colon cancer. Vascular endothelial growth factor plays a major role in neoangiogenesis and is overexpressed in a number of gastrointestinal malignancies. The goal of this study was to evaluate the expression of cyclooxygenase-2 and vascular endothelial growth factor and to assess neoangiogenesis and epithelial cell proliferation in patients with ileal pouch-anal anastomosis.

METHODS

Endoscopic biopsies were obtained from 15 patients with ileal pouch-anal anastomosis without pouchitis (10 biopsies from the ileal pouch and 10 from ileal nonpouch mucosa) and from 15 subjects with irritable bowel syndrome (10 biopsies from normal-appearing ileum and rectum). Cyclooxygenase-1, cyclooxygenase-2, and vascular endothelial growth factor messenger ribonucleic acid expression was determined by reverse transcriptase polymerase chain reaction. Cyclooxygenase-2 and vascular endothelial growth factor protein expression was evaluated by Western blot. Cyclooxygenase-2, vascular endothelial growth factor, CD34 (neoangiogenesis marker), and Ki67 (proliferation marker) mucosal localizations were evaluated by immunohistochemistry.

RESULTS

Expression of cyclooxygenase-2 and vascular endothelial growth factor was increased in ileal pouch mucosa compared with ileal nonpouch mucosa, normal ileum, and rectum. Cyclooxygenase-2 and vascular endothelial growth factor immunostaining in ileal pouch mucosa was more intense in the crypt area than in the surface epithelium compared with ileal nonpouch mucosa. CD34 (neoangiogenesis marker) and Ki67 (proliferation marker) expression was increased in ileal pouch mucosa.

CONCLUSIONS

Cyclooxygenase-2 and vascular endothelial growth factor are overexpressed in the ileal pouch mucosa. This is associated with increased proliferative activity and neoangiogenesis. Cyclooxygenase-2 and vascular endothelial growth factor overexpression might play a role in the pathogenesis of pouchitis.

Systematic review of dysplasia after restorative proctocolectomy for ulcerative colitis

Background

The aim of this systematic review was to assess the prevalence and site of dysplasia after restorative proctocolectomy (RPC) for ulcerative colitis (UC), and to identify risk factors that could be used in a surveillance programme.

Methods

Medical databases were searched for potentially relevant publications between 1978 and 2006. Studies that dealt with RPC for UC and postoperative surveillance were included. Two researchers independently performed study selection, quality assessment, data extraction and analysis.

Results

Twenty-three observational studies and case series were included, with a total of 2040 patients. The pooled prevalence of confirmed dysplasia in the pouch, anal transitional zone or rectal cuff was 1·13 (range 0–18·75) per cent. The prevalence of high-grade dysplasia, low-grade dysplasia and indefinite for dysplasia was 0·15 (range 0–4·49), 0·98 (range 0–15·62) and 1·23 (range 0–25·28 per cent) respectively. Dysplasia was equally frequent in the pouch and rectal cuff or anal transitional zone. Dysplasia and cancer identified before or at operation seemed to be significant predictors of the development of dysplasia. Pouchitis and duration of follow-up were not of predictive value.

Conclusion

Although based on low-level evidence from uncontrolled studies, the prevalence of dysplasia observed after RPC was remarkable. A surveillance programme that takes into account the risk factors found is therefore advocated.

Dysbiosis and pouchitis

BACKGROUND AND METHODS

The exact aetiology of pouchitis is unknown, but an association with dysbiosis has been suggested. This is a retrospective review of 17 studies published between 1985 and 2005, identified by a search of the Medline, Pubmed and Embase databases.

RESULTS

The methodology of the studies varied widely. Many were performed at a time when the distinction between a healthy and an inflamed pouch was vague; misclassification of patients makes the analysis of data difficult and conclusions uncertain.

CONCLUSION

The evidence that dysbiosis is a cause of pouchitis is poor. Nevertheless, available data allow the construction of an algorithm to aid management and suggest a structured approach for future research.

Increased bacterial permeation in long-lasting ileoanal pouches

BACKGROUND AND AIMS

Bacterial overgrowth appears to play an important role in the pathogenesis of ileoanal pouches. Therefore, the capability of bacterial permeation and its determinants is of great interest. The aim of this study was to examine bacterial permeation in the ileoanal pouch and to correlate the results with the degree of inflammation, the epithelial resistance, the mucosal transport function, and the age of the ileoanal pouches.

MATERIALS AND METHODS

Biopsies were taken from 54 patients before colectomy (n = 13; preileal pouch-anal anastomosis [IPAA]), and closure of ileostomy (n = 7; deviation), <1 year after closure of ileostomy (n = 8; intact pouch I), >1 year after closure of ileostomy (n = 16; intact pouch II), in the case of pouchitis (n = 11), and in 11 controls. Tissues were mounted in a miniaturized Ussing chamber. Escherichia coli was added to the mucosal side of the Ussing chamber, and the permeation was proven by serosal presence of E. coli. Epithelial and subepithelial resistance was determined by transmural impedance analysis. Active Na-glucose cotransport and active Cl secretion were measured. Specimens were analyzed by fluorescent in situ hybridization with oligonucleotide probes targeting the bacterial 16s ribosomal RNA. The bacteria in and on the tissue were enumerated.

RESULTS

Bacterial permeation occurred in 2 of 13 pre-IPAA, 2 of 7 deviations, 0 of 8 intact pouch I, 9 of 16 intact pouch II, 5 of 11 pouchitis specimens, and 0 of 11 ileum controls. The frequency of bacterial permeation in the intact pouch II group is higher than in the intact pouch I group (P < 0.001). Epithelial resistance, mannitol fluxes, electrogenic chloride secretion, sodium-glucose cotransport of the bacterially permeated specimens versus nonpermeated of the intact pouch II group, and the pouchitis group and subepithelial resistance remained unchanged. Intramural bacteria could be detected by fluorescence in situ hybridization mainly in long-lasting pouches, but there was no correlation with bacterial permeation.

CONCLUSIONS

The long-lasting ileoanal pouch is associated with increased bacterial permeability. This is not correlated with a disturbed function of the pouch mucosa but could be a precursor of pouchitis.

Systematic review: the management of pouchitis

Pouchitis is the most common complication following proctocolectomy and ileal pouch-anal anastomosis in patients with ulcerative colitis. We aim at discussing relevant information on epidemiology, clinical features, risk factors, diagnostic testing, differential diagnosis and treatment of this idiopathic inflammatory condition. A computerized search of PubMed was performed with the search term 'pouchitis', limited to English papers on humans. This strategy identified 514 references. Relevant articles were selected from this list. In addition, the reference list for each of the selected articles was reviewed to identify any additional references. Pouchitis occurs in up to 60% of patients after ileal pouch-anal anastomosis for ulcerative colitis, and has characteristic clinical, endoscopic and histological features. The most important test for diagnosis is pouch endoscopy with biopsy. Antibiotics remain the mainstay of treatment, and other options are discussed for those patients who are refractory to antibiotic therapy.

A characterization of anaerobic colonization and associated mucosal adaptations in the undiseased ileal pouch

INTRODUCTION

The resolution of pouchitis with metronidazole points to an anaerobic aetiology. Pouchitis is mainly seen in patients with ulcerative colitis pouches (UCP). We have recently found that sulphate reducing bacteria (SRB), a species of strict anaerobe, colonize UCP exclusively. Herein, we aimed to correlate levels of different bacterial species (including SRB) with mucosal inflammation and morphology.

METHODS

Following ethical approval, fresh faecal samples and mucosal biopsies were taken from 9 patients with UCP and 5 patients with familial adenomatous polyposis pouches (FAPP). For the purposes of comparison, faecal samples and mucosal biopsies were also taken from the stomas of 7 of the 9 patients with UC (UCS). Colonization by four types of strict anaerobes (SRB, Clostridium perfringens, Bifidobacteria and Bacteroides) as well as by three types of facultative anaerobes (Enterococci, Coliforms and Lactobacilli) was evaluated. Inflammatory scores and mucosal morphology were assessed histologically in a blinded fashion by a pathologist.

RESULTS

In general, strict anaerobes predominated over facultative in the UCP (P = 0.041). SRB were present in UCP exclusively. Even after exclusion of SRB from total bacterial counts, strict anaerobes still predominated. In the UCS, facultative anaerobes predominated. Strict and facultative anaerobes were present at similar levels in the FAPP. Enterococci were present at significantly reduced levels in the UCP when compared with the UCS (P = 0.031). When levels of SRB and other anaerobic species were individually correlated with mucosal inflammation and morphology, no trends were observed.

CONCLUSION

We have previously identified that SRB exclusively colonize UCP. In addition we have now identified a novel increase in the strict/facultative anaerobic ratio within the UCP compared to UCS. These stark differences in bacterial colonization, however, appear to have limited impact on mucosal inflammation or morphology.

Diagnosis and treatment of pouchitis

Total proctocolectomy with ileal pouch-anal anastomosis is the surgical procedure of choice for the management of ulcerative colitis. Pouchitis, a non-specific inflammation of the ileal reservoir, is the most frequent complication that patients experience in the long-term. Diagnosis should be made on the basis of clinical, endoscopic and histological aspects. The Pouchitis Disease Activity Index (PDAI) represents an objective and reproducible scoring system for pouchitis: active pouchitis is defined as a score > or = 7 and remission as a score < 7. About 15% of patients develop a chronic disease. Treatment of pouchitis is empirical, and very few controlled studies have been carried out. Antibiotics, particularly metronidazole and ciprofloxacin, are the treatment of choice. Chronic pouchitis may benefit from a prolonged course of a combination of antibiotics. Highly concentrated probiotics are effective for both prevention of relapses and prevention of pouchitis onset. There is no convincing evidence of the efficacy of other therapeutic agents.

Sulfate-reducing bacteria colonize pouches formed for ulcerative colitis but not for familial adenomatous polyposis

PURPOSE

Ileal pouch-anal anastomosis remains the "gold standard" in surgical treatment of ulcerative colitis and familial adenomatous polyposis. Pouchitis occurs mainly in patients with a background of ulcerative colitis, although the reasons for this are unknown. The aim of this study was to characterize differences in pouch bacterial populations between ulcerative colitis and familial adenomatous pouches.

METHODS

After ethical approval was obtained, fresh stool samples were collected from patients with ulcerative colitis pouches (n = 10), familial adenomatous polyposis (n = 7) pouches, and ulcerative colitis ileostomies (n = 8). Quantitative measurements of aerobic and anaerobic bacteria were performed.

RESULTS

Sulfate-reducing bacteria were isolated from 80 percent (n = 8) of ulcerative colitis pouches. Sulfate-reducing bacteria were absent from familial adenomatous polyposis pouches and also from ulcerative colitis ileostomy effluent. Pouch Lactobacilli, Bifidobacterium, Bacteroides sp, and Clostridium perfringens counts were increased relative to ileostomy counts in patients with ulcerative colitis. Total pouch enterococci and coliform counts were also increased relative to ileostomy levels. There were no significant quantitative or qualitative differences between pouch types when these bacteria were evaluated.

CONCLUSIONS

Sulfate-reducing bacteria are exclusive to patients with a background of ulcerative colitis. Not all ulcerative colitis pouches harbor sulfate-reducing bacteria because two ulcerative colitis pouches in this study were free of the latter. They are not present in familial adenomatous polyposis pouches or in ileostomy effluent collected from patients with ulcerative colitis. Total bacterial counts increase in ulcerative colitis pouches after stoma closure. Levels of Lactobacilli, Bifidobacterium, Bacteroides sp, Clostridium perfringens, enterococci, and coliforms were similar in both pouch groups. Because sulfate-reducing bacteria are specific to ulcerative colitis pouches, they may play a role in the pathogenesis of pouchitis.

Upregulation of Fas-Fas-L (CD95/CD95L)-mediated epithelial apoptosis--a putative role in pouchitis?

INTRODUCTION

Ileal pouch-anal anastomosis (IPAA) remains the gold standard for patients with refractory ulcerative colitis. Pouchitis causes considerable morbidity in 40% of patients with IPAA. This study examined the role of increased epithelial apoptosis in the etiology of pouchitis.

METHODS

Following ethical approval pouch biopsies taken from patients with a history of pouchitis were compared with age-matched controls from patients who were pouchitis free. Apoptosis was detected immunohistochemically using a monoclonal antibody (M30) and terminal deoxyribonucleotidyl transferase (TDT)-mediated dUTP-digoxigenin end labeling (TUNEL). Villous atrophy was assessed histologically and correlated with levels of apoptosis. Epithelial Fas-ligand (L) was also assessed immunohistochemically.

RESULTS

A significant increase in TUNEL staining was seen at the epithelial but not at the lamina propria level for known pouchitis patients versus controls (0.091 vs 0.035; P < 0.01). Similarly, epithelial M30 immunoreactivity (0.225 vs 0.082; P < 0.05) and villous atrophy (0.035 vs 0.10; P < 0.05) were significantly increased in pouches with previous pouchitis when compared with normal pouches. Upregulation of Fas-L expression was characteristic of this epithelium. Mononuclear cells were strongly positive for Fas-L. Increased epithelial levels of apoptosis correlated with increased levels of villous atrophy.

CONCLUSIONS

Our data suggest a role for elevated Fas-Fas-L (CD95-CD95L)-mediated epithelial apoptosis in the etiology of pouchitis. Increased levels of villous atrophy may result from increased apoptosis and thereby predispose to infection by otherwise apathogenic organisms.

Pouch and pouchitis

Pouchitis is an inflammation of unknown origin occurring in the ileal pouch after IPAA. It is considered by many to be a form of ulcerative colitis that recurs in the pouch and rarely, if ever, occurs in patients with FAP. Most patients respond to a short course of antibiotics. When remission cannot be maintained or the disease is nonresponsive to prolonged treatment with antibiotics, anti-inflammatory agents or steroids may be useful. A variety of alternative drugs have been tried with mixed success and should be considered as experimental. Rarely, when pouchitis is refractory to medical management, excision of the pouch may be required.

Pattern of mucosal adaptation in acute and chronic pouchitis

PURPOSE

Variant pathological changes have been observed in ileoanal pouches, including inflammation, villous atrophy, and crypt hyperplasia. Therefore, we investigated the type and degree of mucosal adaptation in patients with ulcerative colitis and familial adenomatous polyposis.

METHODS

Forty-two patients with ulcerative colitis and 14 patients with familial adenomatous polyposis with ileoanal pouches were assessed. Samples were taken from three months to eight years after creation of an ileoanal pouch. Mucosal architecture was examined by morphometry after microdissection.

RESULTS

Structural changes of the mucosa can be categorized into three groups. Compared with preoperative values, patients without pouchitis (73 percent) has only minor decrease of villous length (402 microm vs. 540 microm) and increase in crypt depth (274.5 microm vs. 177 microm). In patients with acute pouchitis (20 percent), a slight increase in villous length (477 microm vs. 402 microm) and pronounced crypt hyperplasia (376 microm vs. 274.5 microm) was observed compared with noninflamed ileoanal pouches. In contrast, in patients with chronic pouchitis (7 percent), severe villous atrophy (62.5 microm) and crypt hyperplasia (543 microm) was found.

CONCLUSIONS

Minor structural changes of ileoanal pouch mucosa develop early as an adaptive response to a new environment. Only in a small group of patients with chronic pouchitis does severe villous atrophy and crypt hyperplasia of the ileoanal pouch mucosa develop, most likely as a consequence of mucosal inflammation.

Antibiotic combination therapy in patients with chronic, treatment-resistant pouchitis

BACKGROUND

Pouchitis is the major long-term complication after ileal pouch-anal anastomosis for ulcerative colitis. About 15% of patients have a chronic, treatment-resistant disease.

AIMS

To evaluate the efficacy of an antibiotic combination for chronic active, treatment-resistant pouchitis.

PATIENTS AND METHODS

Eighteen patients were treated orally with rifaximin 1 g b.d. + ciprofloxacin 500 mg b.d. for 15 days. Symptoms assessment, endoscopic and histological evaluations were performed at screening and after 15 days using the Pouchitis Disease Activity Index (PDAI). Improvement was defined as a decrease of at least 3 points in PDAI score, and remission as a PDAI score of 0. Systemic absorption of rifaximin was determined by high performance liquid chromatography. Faecal samples were collected before and after antibiotic treatment for stool culture.

RESULTS

Sixteen out of 18 patients (88.8%) either improved (n=10) or went into remission (n=6); the median PDAI scores before and after therapy were 11 (range 9-17) and 4 (range 0-16), respectively (P < 0.002). No side-effects were reported. Rifaximin plasma levels and urinary excretion were negligible, confirming its mainly topical activity. A significant decrease in total anaerobes and aerobes, enterococci, lactobacilli, bifidobacteria and bacteroides in faecal samples was observed, while the reduction in number of coliforms and Clostridium perfringens did not reach a statistical significance.

CONCLUSIONS

A combination of rifaximin and ciprofloxacin was effective in patients with active chronic, treatment-resistant pouchitis, suggesting the need, in these patients, for treatment using antibiotic agents with wide antibacterial spectrum of activity.

Crohn's-like complications in patients with ulcerative colitis after total proctocolectomy and ileal pouch-anal anastomosis

Total proctocolectomy with ileal pouch-anal anastomosis (IPAA) has become an established surgical procedure for ulcerative colitis. Occasional patients who have undergone IPAA develop persistent or recurrent episodes of pouchitis (chronic pouchitis), from which a subset also develop gastrointestinal and systemic complications that are identical to those seen in Crohn's disease. These complications include enteric stenoses or fistulas in the pouch or pouch inlet segment, perianal fistulas or abscesses, pouch fistulas, arthritis, iridocyclitis, and pyoderma gangrenosum. The development of Crohn's-like gastrointestinal complications in a patient with chronic pouchitis frequently engenders concern that the pathologist misinterpreted the proctocolectomy specimen as ulcerative colitis instead of Crohn's disease. We describe eight patients who developed chronic pouchitis and Crohn's-like complications after IPAA and total proctocolectomy. In each case, concern was voiced about misinterpretation of the proctocolectomy specimen as ulcerative colitis instead of Crohn's disease after the development of the Crohn's-like complications. Preoperatively, all eight patients had characteristic clinical, radiographic, and pathologic features of ulcerative colitis. Review of the pathology specimens indicated that all eight had ulcerative colitis. Crohn's-like complications are most likely related to chronic pouchitis, which probably is a form of recrudescent ulcerative colitis within the novel environment of the pouch. A diagnosis of Crohn's disease after IPAA surgery should only be made when reexamination of the original proctocolectomy specimen shows typical pathologic features of Crohn's disease, Crohn's disease arises in parts of the gastrointestinal tract distant from the pouch, pouch biopsies contain active enteritis with granulomas, or excised pouches show the characteristic features of Crohn's disease, including granulomas. There were no histologic differences in the total colectomy specimens between the eight ulcerative colitis study patients and 16 control ulcerative colitis patients who had a favorable clinical outcome after IPAA surgery groups. Crohn's-like complications and chronic pouchitis does not necessarily imply an incorrect original interpretation of ulcerative colitis by the pathologist.

Long-term efficacy of bismuth carbomer enemas in patients with treatment-resistant chronic pouchitis

BACKGROUND

Mucosal inflammation of the ileal pouch (pouchitis) is the major long-term complication after ileal pouch-anal anastomosis for ulcerative colitis. Broad-spectrum antibiotics are the mainstay of treatment, however, 15% of patients with pouchitis have a chronic, treatment-resistant disease.

AIM

To determine the safety and efficacy of bismuth carbomer enemas in achieving and maintaining remission in treatment-resistant chronic pouchitis.

METHODS

Twelve patients with treatment-resistant chronic pouchitis were treated nightly for 45 days with enemas containing elemental bismuth complexed with carbomer. Diagnosis of pouchitis and response to treatment were evaluated with the Pouchitis Disease Activity Index (PDAI), which includes clinical, sigmoidoscopic and histological criteria. Serum bismuth concentrations were determined by atomic absorption.

RESULTS

Ten of 12 patients (83%) went into remission, with a significant decrease of mean total PDAI score from 12 (range 9-15) to 6 (4-15) (P < 0.002), and were continued on bismuth carbomer enemas administered every third night for 12 months. Patients were monitored clinically, sigmoidoscopically and histologically every 2 months for evidence of recurrence (increase > or = 2 in the clinical symptom portion of the PDAI). Six of 10 patients (60%) were able to maintain remission throughout the 12-month trial; 4/10 had an exacerbation, two of which occurred soon after discontinuing daily treatment. Serum bismuth levels were negligible in all patients and no side-effects were registered.

CONCLUSIONS

Our findings suggest that bismuth carbomer enemas are safe and effective in achieving and maintaining remission in patients with treatment-resistant chronic pouchitis.

Ileal pouches: adaptation and inflammation

Ileal pouch-anal anastomosis (IPAA) has become the operation of choice following proctocolectomy for ulcerative colitis (UC) and familial adenomatous polyposis. Functioning ileal pouch mucosa undergoes histological changes resembling the colon (colonic metaplasia). The possible role of stasis and luminal factors--bile acids, short-chain fatty acids and bacteria--are discussed. It seems likely that colonic metaplasia is an adaptive response to the new luminal environment in IPAA. Inflammation in the ileal reservoir ('pouchitis') is the most significant late complication in IPAA. It occurs in 20-30% of patients and is virtually confined to those with prior UC. The clinical picture in pouchitis is highly variable; however, it can be easily categorized into three groups. Nevertheless, in most cases it is likely to represent recurrent UC in the ileal pouch. Current treatments and possible preventative strategies for pouchitis have been outlined.

Metabolic consequences of total colectomy

Colectomy is performed for inflammatory bowel disease, familial polyposis syndrome and colorectal carcinoma. Surgical procedures are ileostomy with or without pouch, ileorectal anastomosis or ileal pouch-anal anastomosis. One of the major functions of the intact large intestine is to absorb water and electrolytes. After colectomy, as much as 400-1000 ml of nearly isotonic ileostomy fluid may be excreted, resulting in a chronic salt and water depletion. This is compensated for by an activation of the renin-angiotensin-aldosterone system. Reduced urine volumes may cause kidney stones. Both dehydration and renal sodium retention are probably less frequent in patients with ileal pouch-anal anastomosis. Absorption of nutrients in general is not impaired by colectomy. The large intestine salvages energy from malabsorbed organic matter through absorption of the short-chain fatty acids produced in bacterial fermentation. In ileostomy patients, fermentation is negligible, which leads to a significant loss of energy in the ileostomy fluid. Pouches are colonized by a bacterial flora similar to colonic bacteria. In these patients conservation of energy from malabsorbed substrate may be similar to healthy subjects. Resection of ileum and bacterial colonization may lead to malabsorption of vitamin B12 and bile acids. The latter may cause increased incidence of biliary cholesterol stones. Pouchitis is a frequent problem which may be caused by a deficiency of short-chain fatty acids and glutamine in the pouch contents. It is concluded that although the colon is not essential as a digestive organ in man, colectomy results in a number of metabolic changes. The ileal pouch-anal anastomosis may in part substitute for the functions of the large intestine.

Pouchitis following pelvic pouch operation for ulcerative colitis. Incidence, cumulative risk, and risk factors

AIM

This study was undertaken to assess the risk for pouchitis in patients with ulcerative colitis who underwent surgery with colectomy, restorative pelvic pouch, and ileoanal anastomosis and to evaluate possible factors predictive for pouchitis development.

PATIENTS AND METHODS

All patients receiving a pelvic pouch because of ulcerative colitis at Huddinge University Hospital between 1980 and 1993 (n = 149; 89 men) were prospectively evaluated for symptoms suggestive of pouchitis. Diagnosis of pouchitis was based on occurrence of certain symptoms in combination with endoscopic findings. Pouchitis was divided into mild and severe, and the time span until the first attack of mild or severe pouchitis was calculated for each patient.

RESULTS

Median follow-up time was 54 (5-152) months. The absolute cumulative risk of developing mild pouchitis was 21, 26, and 39 percent at 6, 12, and 48 months, respectively. The corresponding cumulative risk of developing severe pouchitis was 9, 11, and 14 percent, respectively. Risk for both groups together was 51 percent at 48 months. The occurrence of pouchitis, calculated at six-month intervals after closure of the loop ileostomy, was highest (23.1 percent) during the first six months. Incidence during the next six-month period was 11.4 percent and then only 3.1 percent thereafter. Thirty-two patients (21.5 percent) had chronic continuous symptoms requiring long-term metronidazole treatment, and 14 (9.4 percent) of those had chronic severe pouchitis. In two patients, removal of the pouch and permanent ileostomy became necessary. Extracolonic manifestations and early onset of ulcerative colitis were predictive factors for developing pouchitis. Former smoking seemed to be a protective factor.

CONCLUSION

The risk for pouchitis was highest during the initial six-month period. Cumulative risk leveled off after two years but was substantial (51 percent) at four years. Less than 10 percent of patients had severe, chronic pouchitis, and only two patients (1.3 percent) had their pouches removed.

Substance P--an underlying factor for pouchitis? Prospective study of substance P- and vasoactive intestinal polypeptide-immunoreactive innervation and mast cells

Recent studies suggest that substance P (SP), vasoactive intestinal polypeptide (VIP), and mast cells play a role in inflammatory processes of the bowel. The aim of this study was to evaluate the distribution of SP and VIP immunoreactivities and to count mast cells in the ileal pouch of patients, who had pouchitis after restorative proctocolectomy performed for treatment of ulcerative colitis (UC), and to compare the findings in the same patients after a follow-up period. Nine patients with pouchitis underwent clinical evaluation, endoscopy of the pouch, and histological examination, which were repeated after the follow-up period of 14 months on average. The number and intensity of SP- and VIP-immunoreactive nerve fibers were visualized by immunofluorescence microscopy and subjected to quantitative scoring, and the number of mast cells per unit area was counted. The results were compared to the histological findings and the clinical status. Lamina propria contained fibers showing bright immunofluorescence for SP and VIP. The mean fluorescence intensity score of SP-immunoreactive nerve fibers in the lamina propria remained similar after the follow-up period (2.99 +/- 0.79 and 2.06 +/- 0.82, NS). SP-immunoreactive innervation correlated with the grade of acute (R2 = 0.5396, P = 0.0242) and chronic inflammation (R2 = 0.4561, P = 0.0459), while SP and VIP immunoreactivity, mast cell count, and histological changes did not correlate with the clinical status. The present study demonstrates an increase in the density of SP-immunoreactive nerve fibers in inflamed ileal pouch mucosa of clinically asymptomatic pouchitis patients. These results raise the possibility of therapeutic interference of SP-related processes in treatment of pouchitis.

Long-term histomorphological surveillance of the pelvic ileal pouch: dysplasia develops in a subgroup of patients

BACKGROUND & AIMS

Little is known about the long-term morphology of the pelvic ileal pouch after restorative proctocolectomy in patients with ulcerative colitis. This study analyzed the mucosal adaptation in the pouch during a long-term follow-up.

METHODS

Mucosal biopsy specimens were obtained from 87 patients during a follow-up of 6.3 years (SD, 2.7; range, 3-14 years). The villous surface density, degree of inflammation, and type of mucin were determined from glycolmethacrylate-embedded sections.

RESULTS

Three basic patterns of mucosal adaptation were observed: regular response with normal mucosa or mild villous atrophy and no or mild inflammation (type A, 51%), transient atrophy response with temporary moderate or severe villous atrophy followed by normalization of architecture (type B, 40%), and constant atrophy response with permanent subtotal or total villous atrophy developing from the early functioning period accompanied by severe pouchitis (type C, 9%). Low-grade dysplasia occurred in 3 patients with type C response.

CONCLUSIONS

In a small group of patients with ulcerative colitis, the mucosa of the pelvic pouch adapts with constant severe villous atrophy accompanied by long-standing pouchitis. This group of patients should be identified and undergo regular endoscopic and histomorphological surveillance because of risk of developing neoplasia in the pouch mucosa.

Bile acid absorption from ileoanal pouches using enema scintigraphy

It is unclear whether bile acid absorption is affected by ileoanal pouch construction. Bile acid absorption was measured in the abdomen of 16 patients with pouches (nine with good and seven with poor pouch function based on a clinical score) and in six patients with an end ileostomy using a radiolabelled synthetic bile acid (75SeHCAT) enema and dynamic scintigraphy. The median (interquartile range) 75SeHCAT absorption was 81 (79-87) per cent in patients with ileostomy, 46 (43-53) per cent in patients having well functioning pouches, and 24 (18-38) per cent in the group with poor pouch function (P < 0.01). Log transformation of the absorption curves revealed a two-component uptake (fast component t1/2 = 1.4-7.2 min; slow component t1/2 = 16-144 min) in all patients with ileostomy, in eight of nine patients with pouches with good function, and in one of seven patients with a poorly functioning pouch (P < 0.05); in the other six patients with poorly functioning pouches, only the slow component of absorption was present. This test showed significantly reduced bile acid absorption in patients with an ileoanal pouch and gave an objective discrimination between well and poorly functioning pouches.

Clinical and physiological aspects of ileal pouch-anal anastomosis

Proctocolectomy with ileal pouch-anal anastomosis is the surgical treatment of choice for severe chronic ulcerative colitis and familial polyposis coli because the entire colonic mucosa is removed while anal function can be preserved and the necessity for permanent ileostomy is eliminated. Long-term functional results are generally gratifying, as defecation frequency and degree of incontinence are acceptable in most patients. Pouchitis, however, a non-specific inflammation of the ileal reservoir, is a major long-term complication occurring in a considerable number of patients. The etiology of pouchitis is unknown. Since pouchitis occurs more frequently or even exclusively in ulcerative colitis patients it is assumed that pouchitis is a novel manifestation of inflammatory bowel disease. However, bacterial overgrowth in the ileal pouch may also play a pathogenetic role. Chronic inflammation and villous atrophy of varying severity is found in virtually all pouches. Acute inflammatory changes and ulceration are associated with pouchitis.