Pouchitis

Inflammation of the pouch after an IPAA (ileal pouch-anal anastomosis)

Epidemiology

Previous UC
- More extensive disease
- Extraintestinal manifestations including PSC
- Younger age at diagnosis or surgery
Coexisting autoimmune or autoinflammatory disorders
Obesity
Smoking (acute pouchitis)
Possibly dietary factors
Possibly J pouches at higher risk than S pouches (?less tension)
PV thrombosis
Faecal stasis

Maybe an abnormal immune response to altered luminal and/or mucosal bacteria in genetically susceptible hosts

Acute vs chronic (<4 weeks)
Frequency of flares
- Episodic (<3 episodes per year)
- Relapsing (>=3/year)
- Chronic
Disease extent
Antibiotic-responsive or resistant
- May evolve over time to be resistant
Pouchitis Disease Activity Index (PDAI)

Clinical criteria
Stool frequency
Usual post-op stool frequency	0
One to two stools/day > post-op usual	1
Three or more stools/day > post-op usual	2
Rectal bleeding
None or rare	0
Present daily	1
Fecal urgency/abdominal cramps
None	0
Occasional	1
Usual	2
Fever (temperature >100°F)
Absent	0
Present	1
Endoscopic criteria
Edema	1
Granularity	1
Friability	1
Loss of vascular pattern	1
Mucus exudate	1
Ulceration	1
Acute histologic criteria
Polymorph infiltration
Mild	1
Moderate + crypt abscess	2
Severe + crypt abscess	3
Ulceration per low-power field (average)
<25 percent	1
≥25 to ≤50 percent	2
>50 percent	3

Broad spectrum of severity and natural history
Increase in stool frequency
Urgency
Bleeding is rare - more suggestive cuffitis, pouch prolapse, or ulcers
Systemic infective symptoms are uncommon, and suggest an infective cause of pouchitis, Crohn disease of the pouch, or surgical complications
Straining or ineffective defecation is more suggestive of an obstructive disorder such as stricture or functional problem with pelvic floor
Abdominal cramping, pelvic pressure
Tenderness of lower abdomen may be present
Elevated CRP
Radiographic findings:
- Pouch thickening
- Mucosal hyperenhancement
- Accumulation of peri-pouch fat
- Pelvic lymphadenopathy

Ischaemic pouchitis - asymmetric inflammation and ulceration of the pouch
Cuffitis - recurrence of UC in the residual cuff of rectal mucosa
- Haematochaezia, circumferential inflammation of rectal cuff, typical UC histologic findings
CD of pouch
Structural or functional pouch outlet obstruction
Post-op complications
Pre-pouch ileitis
Diversion pouchitis - anal discharge of blood/mucus/urgency
Irritable pouch syndrome
De novo coeliac disease

Bloods
Pouchoscopy and mucosal biopsies
- Look for diffuse erythema, friability, granularity, exudates, erosions, ulcerations
- Pre-pouch ileitis may be present
- Don't biopsy the suture line - may be reported as granulomas, wrongly suggestive of CD
Stool studies to exclude infection

Treatment goals
- Alleviate symptoms
- Improve quality of life
- Achieve clinical and endoscopic remission by demonstrating mucosal healing
Primary prevention
- Minimise NSAIDs
- Maintain healthy weight
Acute idiopathic pouchitis
- Avoid NSAIDs
- Diet low in poorly digested carbohydrates and fibre (although there are variable recommendations… refer to dietician with expertise)
- Oral antibiotic for two weeks (ciprofloxacin 500mg BD, or metronidazole 500mg BD). If no response, culture the stool and give four weeks of antibiotics based on susceptibility.
- Pouch lavage?
Relapsed acute pouchitis
- PO Abx
- Consider maintenance therapy for those with frequent relapses
Chronic pouchitis
- Probiotic
CARP
- Screen for PSC, IgG4 disease, or other secondary cause
- Trial topical mesalamine for four weeks
- If effective, basically manage as UC
- Biologics are available for refractory cases

Most patients with acute pouchitis settle with antibiotics, but 50-90% will have at least one recurrence and 30% will get chronic pouchitis
If chronic antibiotic-refractory pouchitis (CARP) develops, it may progress to pouch failure requiring permanent diversion