Reasoning GP · Algorithm · 1-page summary
Faecal incontinence in adults
For: adults with leakage of stool, any setting including care homes. Not for: children (unexplained FI in a child → safeguarding, block 2).
Core rule: exclude cauda equina and colorectal red flags, then examine for faecal loading before calling it diarrhoea. Overflow is the most commonly missed cause, and loperamide makes it worse.
0Stop — emergency now — before the bowel history
- New incontinence with saddle sensory disturbance, new urinary retention or loss of urinary sensation, reduced anal tone, bilateral or progressive leg weakness, or severe back pain with new bladder or bowel dysfunction → suspected cauda equina → Emergency spinal assessment + emergency MRI
- Sepsis, shock, rapidly progressive perianal infection or Fournier's gangrene (crepitus, spreading perianal necrosis) → 999
- Severe abdominal pain, distension and vomiting (absolute constipation) with suspected obstruction from impaction → 999 / emergency
- Do not delay transfer for primary-care tests. FI alone, without compatible neurological signs, is not cauda equina.
1Triage by type of leakage — a pointer only; often multifactorial
| Leakage | Think |
|---|---|
| Passive | No warning. Internal sphincter weakness, neuropathy, prolapse. |
| Urge | Cannot defer. External sphincter weakness, rectal inflammation (IBD, radiation), IBS-D. |
| "Diarrhoea" | Older, immobile or constipated → overflow until examination excludes loading. |
| Loose stools | Medicines, IBD, microscopic colitis, bile acid, coeliac disease. |
2Screen — one row is enough
- NG12 colorectal symptoms (e.g. change in bowel habit, iron-deficiency anaemia, unexplained rectal bleeding, weight loss) → offer FIT; ≥10 µg Hb/g → Suspected cancer pathway. FI alone is not a FIT indication.
- Rectal mass, unexplained anal mass or ulceration → Suspected cancer pathway, no FIT. Low FIT but concern persists → refer anyway.
- Perianal abscess → urgent surgical drainage, not antibiotics alone; systemically unwell → Same-day
- Rectal bleeding with instability → Same-day colorectal
- Progressive neurological symptoms without cauda equina features → neurology referral and MRI spine.
- Safeguarding: unexplained FI or anal injury in a child or vulnerable adult → document objectively; discuss with safeguarding per local policy.
3Assess — only once blocks 0–2 are answered
☐ Obstetric, surgical, radiotherapy and medicine history ☐ Abdomen: loading, mass ☐ Perianal: skin, gaping anus, prolapse, scars, fistula ☐ DRE with consent and chaperone: tone, squeeze, loading, mass ☐ Cognition, mobility, toilet access ☐ Bowel diary with Bristol type
Tests only as directed (FBC, CRP, coeliac, calprotectin, stool tests). Not in primary care: anorectal physiology, endoanal ultrasound.
4Classify — only if the screen is negative
- Overflow — loading on abdomen or DRE → disimpact; no antidiarrhoeals.
- Obstetric sphincter injury — previous 3rd/4th degree tear → specialist continence or colorectal pathway.
- Prolapse or rectocele — seen on straining, incomplete evacuation → colorectal if symptomatic.
- Loose-stool driven — metformin, excess laxatives, SSRIs, NSAIDs or PPIs (microscopic colitis), antibiotics, IBD, IBS-D → treat the cause.
- Neurological — diabetes, MS, stroke, Parkinson's, dementia → bowel programme.
- Uncertain or mixed — say so; bowel diary, initial measures and a set review.
5Treat today — doses: NICE/SPC, BNF, local formulary
- Impaction: rectal first (glycerol or bisacodyl suppository, or enema; phosphate enema only if no renal impairment, heart failure, frailty, electrolyte or rectal mucosal disease); oral macrogol if that fails and obstruction excluded; then maintenance.
- Loose stools, loading excluded: loperamide 0.5–16 mg/day, start low and titrate. Not with hard stools, impaction, obstruction, acute undiagnosed or bloody diarrhoea, or severe colitis.
- Bowel programme: predictable stool; one dietary change at a time; never restrict fluids; toileting after meals; pelvic-floor exercises.
- Skin and support: barrier product; review culprit medicines; Talking Therapies, Bladder and Bowel UK.
6Refer routinely — no fixed wait if earlier input is needed
- Persists after initial measures, or severe → continence service (pelvic-floor programme, biofeedback, irrigation).
- Early colorectal: symptomatic tear, prolapse, significant rectocele, fistula, sphincter defect, FI after anal surgery or pelvic radiotherapy.
- Loose-stool FI → gastroenterology (IBD, microscopic colitis, bile acid). Specialist only: nerve stimulation, sphincter repair.
7Never reassure by
- "Diarrhoea" in an older or immobile patient — examine for impaction first.
- A normal DRE: proximal loading is still possible.
- A low or unreturned FIT when symptoms persist.
- Delivery or surgery "years ago" — sphincter injury can present decades later.
- "Just old age" after a stroke, in dementia or in a care home.
- The patient not raising it — ask high-risk groups directly.
8Safety-net — say it, then document it
999 / A&E “Go to A&E now, or call 999, if you get numbness between the legs or around the bottom, cannot pass urine, weakness in both legs, a hot spreading painful area near the back passage with feeling very unwell, or severe tummy pain with swelling and vomiting.” Same day: “New bleeding from the back passage, losing weight quickly, new or worsening leg weakness, or a painful swelling near the back passage — contact us today.”
Remote or OOH: book face to face — loading, a mass and prolapse need examination. Not improving at review → continence service.
✓Safe to leave primary care only if — all five, documented
No block 0–2 row applies; NG12 symptoms → FIT or referral
Abdomen and DRE done (or reason recorded); loading excluded
Medicines reviewed; cause or "multifactorial" stated
Safeguarding and care support considered
Safety-net given; review and referral owner set
Summary of the full Reasoning GP faecal incontinence algorithm, which holds the detail, causes, examination and evidence. Sources: NICE CG49, QS54, NG12 (updated April 2026), HTG690, HTG61, HTG135. Clinical reference — follow local emergency and cauda equina pathways and check doses: NICE/SPC, BNF.