Gastroenterology: Bowel Disorders (Complete)

• Diarrhoea and malabsorption: Approach to Chronic Diarrhoea | Coeliac Disease | Bile Acid Diarrhoea | Other Causes of Malabsorption | Clostridioides difficile Infection
• Functional and motility: Irritable Bowel Syndrome | Chronic Constipation
• Colon: Diverticular Disease | Colorectal Polyps | Colorectal Cancer | Bowel Cancer Screening | Inherited Bowel Cancer Syndromes | Vascular Bowel Disorders
• Anorectal: Haemorrhoids and Anal Fissure | Other Anorectal Conditions
• Revision: Drug Reference Table | Spot the Diagnosis | Exam-style Scenarios | Key Points | Guidelines and Further Reading

🧻 Bowel disorders range from the very common (IBS, constipation, haemorrhoids) to the very important (colorectal cancer, the second biggest cancer killer in the UK). The key skills are spotting who needs urgent investigation, finding treatable causes of diarrhoea, and managing functional symptoms well.
Your four questions for every patient: Are there red flags (rectal bleeding, change in bowel habit over 50, iron deficiency, weight loss, a mass)? What does the FIT or calprotectin show? Is there a treatable cause such as coeliac disease, bile acid diarrhoea, drugs or infection? If tests are normal, can I confidently diagnose and treat a functional disorder?

Approach to Chronic Diarrhoea

Definition: Looser or more frequent stools for more than 4 weeks.

Red flags - investigate promptly:

• Age over 50 with a change in bowel habit.
• Rectal bleeding.
• Weight loss.
• Iron deficiency anaemia.
• Night-time diarrhoea.
• Family history of bowel cancer or IBD.
• Abdominal or rectal mass.

Clues from the history:

• Bloody - IBD, infection, cancer, ischaemia.
• Watery - microscopic colitis, bile acid diarrhoea, drugs, neuroendocrine tumours, overflow.
• Pale, greasy, foul, hard to flush (steatorrhoea) - fat malabsorption: pancreatic insufficiency, coeliac disease.
• After cholecystectomy or ileal resection - bile acid diarrhoea.
• Drugs - metformin, PPIs, SSRIs, NSAIDs, magnesium, antibiotics, laxative misuse, alcohol.
• Travel - giardiasis.
• Thyrotoxicosis, diabetes (autonomic neuropathy).

First tests (BSG chronic diarrhoea guideline):

• FBC, U&E, LFTs, CRP, ferritin, B12, folate, calcium, TFTs.
• Coeliac serology (tTG with total IgA).
• Faecal calprotectin (under 40s or where IBD is suspected).
• FIT if cancer is possible.
• Stool culture, ova and parasites, and C. difficile if relevant.

Second-line tests as guided:

• Colonoscopy with biopsies - always biopsy even if normal (microscopic colitis).
• SeHCAT scan (bile acid diarrhoea).
• Faecal elastase (pancreatic insufficiency).
• OGD with duodenal biopsies.
• Breath tests (SIBO, lactose).
• Gut hormones (neuroendocrine tumours).

💡 Clinical Pearl: In older people, "diarrhoea" is often overflow around faecal impaction. Always do a rectal examination before adding treatment.

↑ Back to index

Coeliac Disease

What it is: An autoimmune reaction to gluten (in wheat, barley and rye) in people with HLA-DQ2 or DQ8. It damages the small bowel lining (villous atrophy) and affects about 1 in 100 people in the UK - most are undiagnosed.

Symptoms - often subtle:

• Diarrhoea, bloating, abdominal pain, weight loss (or none).
• Fatigue.
• Iron, folate or B12 deficiency.
• Mouth ulcers.
• Raised liver enzymes.
• Low bone density.
• Subfertility and recurrent miscarriage.
• Neurological symptoms (ataxia, neuropathy).
• Children: faltering growth.
• Dermatitis herpetiformis - itchy blisters on the elbows, knees and buttocks; it is coeliac disease of the skin.

Who to test:

• The symptoms above.
• IBS-type symptoms.
• Type 1 diabetes; autoimmune thyroid disease.
• First-degree relatives.
• Down and Turner syndromes.
• Microscopic colitis.

Diagnosis (BSG 2026 guideline):

• The patient must be eating gluten (in more than one meal a day for at least 6 weeks) - tests are falsely negative on a gluten-free diet.
• IgA tTG with total IgA. In IgA deficiency, use IgG-based tests and biopsy.
• Duodenal biopsies at OGD (4 from the second part of the duodenum and 2 from the bulb) - Marsh classification.
• No-biopsy route - now an option for symptomatic adults seen in secondary care with IgA tTG 10 times or more the upper limit of normal, after discussion. Biopsy is still needed for red flags or doubt.
• HLA-DQ2/DQ8 typing - mainly to exclude coeliac disease (a negative result makes it very unlikely).

Treatment:

• Lifelong strict gluten-free diet - with a specialist dietitian. Gluten-free oats are usually tolerated.
• Correct deficiencies (iron, folate, vitamin D, calcium).
• DEXA scan (often at diagnosis or after a year).
• Pneumococcal vaccine (hyposplenism).
• Annual review at first, with tTG to check adherence (it should fall). Patient-initiated follow-up once stable.
• Dermatitis herpetiformis: Gluten-free diet, plus dapsone in the short term (check G6PD first).

Ongoing symptoms despite treatment:

• The commonest cause is gluten exposure (often accidental).
• Consider IBS, microscopic colitis, lactose intolerance, SIBO, pancreatic insufficiency.
• Refractory coeliac disease (rare) - persistent villous atrophy despite a strict diet for 12 months. Type 2 carries a risk of enteropathy-associated T-cell lymphoma. Refer to a specialist centre.

Complications:

• Osteoporosis.
• Hyposplenism.
• Small bowel lymphoma (EATL) and adenocarcinoma.
• Oesophageal cancer (small increase).
• Risks fall with a gluten-free diet.

↑ Back to index

Bile Acid Diarrhoea

What it is: Bile acids that are normally reabsorbed in the terminal ileum reach the colon and cause watery diarrhoea. It is common and under-diagnosed - up to a third of people with "IBS-diarrhoea" may have it.

Types:

• Type 1 - ileal disease or resection (Crohn's).
• Type 2 - primary (idiopathic; too much bile acid made).
• Type 3 - other causes: after cholecystectomy, after pelvic radiotherapy, SIBO, coeliac disease, diabetes, microscopic colitis.

Symptoms:

• Urgent watery diarrhoea, often after meals and in the morning.
• Faecal incontinence.
• Bloating.

Diagnosis: SeHCAT scan - a swallowed radiolabelled bile acid. Under 15% retained at 7 days confirms it (under 5% is severe). Serum C4 is an alternative where available. A treatment trial is reasonable if testing isn't available.

Treatment:

• Bile acid sequestrants:
  • Colestyramine 4 g sachet, 1–4 times daily.
  • Colesevelam (tablets, better tolerated; off-label).
  • Colestipol.
• Give other drugs 1 hour before or 4–6 hours after - sequestrants bind them (e.g. levothyroxine, warfarin, the pill).
• Long term, they can cause deficiency of fat-soluble vitamins.
• Low-fat diet; loperamide.

↑ Back to index

Other Causes of Malabsorption

• Lactose intolerance:
  • Loss of lactase - common in people of African, Asian and South American descent; can follow gastroenteritis or coeliac disease.
  • Bloating, wind and diarrhoea after dairy.
  • Trial of a low-lactose diet; hydrogen breath test.
  • Small amounts of dairy are usually tolerated; hard cheese and yoghurt are better tolerated.
• Small intestinal bacterial overgrowth (SIBO):
  • Risk factors:
    • Blind loops after surgery.
    • Strictures.
    • Diverticula.
    • Poor motility (diabetes, systemic sclerosis).
    • Low stomach acid (PPIs).
    • Older age.
  • Symptoms: Bloating, diarrhoea, B12 deficiency (bacteria use it), with normal or high folate (bacteria make it).
  • Diagnosis: Glucose or lactulose hydrogen breath test, or small bowel aspirate.
  • Treatment: Antibiotics (e.g. rifaximin, doxycycline, co-amoxiclav); treat the cause.
• Pancreatic exocrine insufficiency: Steatorrhoea and weight loss. Low faecal elastase. Pancreatic enzyme replacement - see the Pancreas and Biliary chapter.
• Giardiasis:
  • Parasite from contaminated water (travel, camping, children's nurseries).
  • Bloating, sulphurous burps, greasy diarrhoea, weight loss.
  • Stool antigen or PCR.
  • Metronidazole (e.g. 400 mg three times daily for 5 days) or tinidazole.
  • Common in IgA deficiency.
• Whipple's disease:
  • Rare infection with Tropheryma whipplei, usually in middle-aged white men.
  • Features:
    • Arthralgia (often years earlier).
    • Diarrhoea and weight loss.
    • Lymphadenopathy; skin pigmentation.
    • Neurological features (dementia, eye movement problems).
    • Culture-negative endocarditis.
  • Duodenal biopsy shows PAS-positive macrophages; PCR.
  • Treatment: IV ceftriaxone for 2 weeks, then oral co-trimoxazole for 12 months. Fatal if untreated.
• Tropical sprue: Malabsorption after long stays in the tropics. Folate deficiency. Treated with tetracycline and folic acid.
• Short bowel syndrome - see the GI Investigations and Nutrition chapter.
• Small bowel lymphoma, neuroendocrine tumours (carcinoid syndrome - flushing and diarrhoea; see the NETs chapter), amyloidosis, radiation enteritis.

↑ Back to index

Clostridioides difficile Infection

What it is: A toxin-producing bacterium that causes diarrhoea and colitis, usually after antibiotics disrupt normal gut bacteria.

Risk factors:

• Antibiotics - especially clindamycin, cephalosporins, co-amoxiclav and quinolones ("the 4 Cs").
• Older age; hospital or care home stays.
• PPIs.
• Immunosuppression; IBD.

Diagnosis:

• Test diarrhoeal stool only (Bristol type 5–7).
• Two-step testing - GDH or PCR (organism present) then toxin test (active infection).
• Severity markers:
  • WCC over 15 × 10⁹/L.
  • Rising creatinine.
  • Temperature over 38.5 °C.
  • Colitis on imaging.
• Life-threatening: Hypotension, ileus, toxic megacolon.

Management (NICE NG199):

• Isolate the patient (side room, gloves and apron). Wash hands with soap and water - alcohol gel does not kill spores.
• Stop the causative antibiotic if possible; review PPIs, laxatives and antimotility drugs.
• First episode: Oral vancomycin 125 mg four times daily for 10 days.
• Second line: Fidaxomicin 200 mg twice daily for 10 days.
• Recurrence within 12 weeks: Fidaxomicin. After 12 weeks: vancomycin or fidaxomicin.
• Life-threatening: Oral vancomycin 500 mg four times daily plus IV metronidazole 500 mg three times daily; urgent surgical review (colectomy).
• Two or more recurrences: Faecal microbiota transplant.
• Monitor fluids, electrolytes and kidney function. Root cause analysis for hospital cases.

↑ Back to index

Irritable Bowel Syndrome

What it is: A common disorder of gut–brain interaction - the gut is oversensitive and moves abnormally, with no structural disease. It affects 10–20% of people, is commonest in young women, and is often triggered by stress or gastroenteritis.

Diagnosis (NICE CG61) - think of IBS if there are 6 months or more of:

• Abdominal pain or discomfort that is relieved by opening the bowels, or linked to a change in stool frequency or form, plus 2 of:
  • Altered passage of stool (straining, urgency, incomplete emptying).
  • Bloating or distension.
  • Worse after eating.
  • Passing mucus.
• Types: IBS with constipation (IBS-C), with diarrhoea (IBS-D), or mixed.

Tests - to exclude other causes:

• FBC, CRP or ESR.
• Coeliac serology.
• Faecal calprotectin (diarrhoea).
• CA125 in women with persistent bloating, especially over 50 (ovarian cancer).
• FIT if there are any lower GI cancer concerns.
• Colonoscopy is not needed without red flags.

Treatment:

• Explain the diagnosis positively - it is real, common and not dangerous.
• Diet:
  • Regular meals; limit caffeine, alcohol, fizzy drinks and fatty food.
  • Adjust fibre - reduce insoluble fibre (bran); try oats or linseed for bloating.
  • Low-FODMAP diet with a dietitian if symptoms persist.
• Drugs by symptom:
  • Pain and spasm: Antispasmodics - mebeverine 135 mg three times daily, hyoscine butylbromide, peppermint oil.
  • Constipation: Soluble fibre (ispaghula), macrogol (avoid lactulose - causes bloating); linaclotide if laxatives have failed after 12 months.
  • Diarrhoea: Loperamide.
• Second line: Low-dose amitriptyline (10 mg at night, increasing to 30–50 mg; the ATLANTIS trial showed benefit in primary care); an SSRI if a tricyclic doesn't help.
• Psychological therapies: CBT, gut-directed hypnotherapy.
• Exercise; probiotics - a 4-week trial.

⚠️ Safety Pearl: New "IBS" symptoms starting over the age of 50 are not IBS until bowel and ovarian cancer have been considered.

↑ Back to index

Chronic Constipation

What it is: Infrequent stools (fewer than 3 a week), hard stools, straining, or a feeling of incomplete emptying. It is very common in older people.

Look for causes:

• Drugs: Opioids, iron, calcium channel blockers, anticholinergics, antidepressants, antipsychotics, aluminium antacids, ondansetron.
• Metabolic: Hypercalcaemia, hypothyroidism, low potassium, diabetes.
• Neurological: Parkinson's, MS, spinal cord damage.
• Structural: Colorectal cancer, strictures.
• Lifestyle: Immobility, low fibre and fluid intake, ignoring the urge.
• Pelvic floor problems: Dyssynergic defaecation, rectocele.

Assessment:

• Red flags (age over 50 with new symptoms, bleeding, weight loss, anaemia).
• Rectal examination - impaction, masses, anal tone.
• Bloods: FBC, calcium, TFTs.
• FIT if cancer is a concern.

Laxatives (step-wise):

• Bulk-forming - ispaghula husk. Needs fluid; avoid in opioid constipation and impaction.
• Osmotic - macrogol (first choice for most), lactulose.
• Stimulant - senna, bisacodyl, sodium picosulfate.
• Softener - docusate.
• Opioid-induced constipation: Osmotic plus stimulant (not bulk-forming). If they fail, use naloxegol (oral) or methylnaltrexone (injection) - peripheral opioid blockers.
• If at least 2 laxatives have failed for 6 months: Prucalopride (a prokinetic) or linaclotide.
• Faecal impaction: High-dose macrogol; suppositories or enemas.

Specialist: Transit studies, anorectal physiology, biofeedback for dyssynergic defaecation, transanal irrigation.

↑ Back to index

Diverticular Disease

Terms:

• Diverticulosis - small pouches in the colon wall, usually in the sigmoid. Very common with age (most over-70s); usually no symptoms.
• Diverticular disease - symptoms (pain, change in bowel habit) from diverticula.
• Diverticulitis - inflammation or infection of a diverticulum.

Risk factors:

• Low-fibre diet.
• Obesity.
• Smoking.
• NSAIDs.
• Older age.

Acute diverticulitis (NICE NG147):

• Symptoms: Left iliac fossa pain, fever, change in bowel habit, raised CRP. Some have right-sided disease (Asian populations).
• Uncomplicated and systemically well: Consider no antibiotics - paracetamol, fluids. Review if symptoms persist or worsen.
• Systemically unwell, immunosuppressed or significant comorbidity: Co-amoxiclav (500/125 mg three times daily for 5 days) - or cefalexin plus metronidazole, or trimethoprim plus metronidazole, if allergic to penicillin.
• Admit if pain is uncontrolled, the patient can't eat or drink, or complications are suspected. CT confirms the diagnosis and shows complications.
• Complications:
  • Abscess (drain radiologically if large).
  • Perforation and peritonitis (Hartmann's procedure).
  • Fistula - colovesical: pneumaturia and recurrent UTIs.
  • Stricture.
  • Bleeding.
• After recovery: Colonoscopy or CT colonography to exclude cancer, if not already done.

Diverticular bleeding: Sudden painless bright red bleeding - usually stops on its own (see the Gastroenterology Emergencies chapter).

Prevention:

• High-fibre diet; fluids.
• Weight loss; stop smoking; exercise.
• No need to avoid nuts, seeds or popcorn.
• Elective surgery only for recurrent complicated disease or ongoing symptoms.

↑ Back to index

Colorectal Polyps

What they are: Growths from the bowel lining. Most bowel cancers develop from polyps over about 10 years (the adenoma–carcinoma sequence), so removing them prevents cancer.

Types:

• Adenomas - tubular, tubulovillous or villous. The risk of cancer rises with size, villous features and dysplasia.
• Serrated lesions - sessile serrated lesions (often flat, right-sided, hard to see; a cause of "interval" cancers).
• Hyperplastic polyps - small ones in the rectum are harmless.
• Inflammatory and hamartomatous polyps.
• Villous adenomas can secrete mucus - causing low potassium.

Surveillance after polyp removal (BSG/ACPGBI/PHE 2020):

• High-risk findings - one-off colonoscopy at 3 years:
  • 2 or more premalignant polyps, including at least one "advanced" polyp (10 mm or more, or with high-grade dysplasia, or serrated with any dysplasia), or
  • 5 or more premalignant polyps.
• Large flat polyps (20 mm or more) removed in pieces: Check the site at 2–6 months, then 12 months later.
• Everyone else: No surveillance - return to the national screening programme if eligible.
• Surveillance generally stops at 75, or earlier if unfit.

↑ Back to index

Colorectal Cancer

The basics: About 44,000 new cases a year in the UK. Most occur over 50, but rates are rising in younger adults.

Risk factors:

• Age.
• Family history and inherited syndromes.
• IBD (extensive colitis, PSC).
• Red and processed meat; low fibre.
• Obesity; inactivity.
• Smoking; alcohol.
• Type 2 diabetes.
• Acromegaly.

Symptoms by site:

• Right side (caecum, ascending colon): Iron deficiency anaemia, weight loss, a right iliac fossa mass; bowel symptoms are often absent.
• Left side and rectum: Rectal bleeding (dark or mixed with stool), change in bowel habit, tenesmus, obstruction.
• Emergency presentations (about 1 in 5): Obstruction, perforation.

Referral (NICE NG12 and DG56):

• Offer FIT to people with symptoms that could be bowel cancer (change in bowel habit, weight loss, abdominal pain, iron deficiency anaemia, rectal bleeding).
• FIT 10 µg Hb/g or more → urgent suspected cancer referral.
• Refer urgently regardless of FIT if there is a rectal or abdominal mass, anal ulceration, or strong clinical concern. A normal FIT does not exclude cancer if the doctor remains worried.

Diagnosis and staging:

• Colonoscopy with biopsy (or CT colonography if unfit).
• CT chest, abdomen and pelvis.
• MRI pelvis for rectal cancer.
• CEA (baseline, for follow-up - not for diagnosis).
• Test every tumour for mismatch repair deficiency (MMR/MSI) - this screens for Lynch syndrome and guides treatment. Also test RAS and BRAF.

Treatment (colorectal MDT):

• Colon cancer:
  • Surgery (right or left hemicolectomy, sigmoid colectomy), increasingly laparoscopic or robotic.
  • Adjuvant chemotherapy (CAPOX or FOLFOX) for node-positive (stage III) and high-risk stage II disease.
• Rectal cancer:
  • Total mesorectal excision, often after radiotherapy or chemoradiotherapy.
  • "Watch and wait" for complete responders.
• Very early cancers in polyps: Endoscopic removal may be enough.
• Metastatic disease:
  • Chemotherapy with targeted drugs (anti-EGFR for RAS wild-type, anti-VEGF).
  • Immunotherapy (pembrolizumab) for MMR-deficient tumours.
  • Resection or ablation of liver or lung metastases in selected patients.
• Emergency obstruction: Resection, a stoma or a colonic stent.
• Follow-up: CEA and CT for 3–5 years; colonoscopy at 1 year and then periodically.

↑ Back to index

Bowel Cancer Screening

• NHS Bowel Cancer Screening Programme (England):
  • Home FIT kit posted every 2 years to people aged 50–74.
  • Over 75s can request a kit.
• Threshold:
  • England lowered the referral threshold from 120 to 80 µg Hb/g from February 2026, so more cancers and advanced polyps are found.
  • Scotland and Wales use similar thresholds.
  • An abnormal result leads to a specialist nurse assessment and colonoscopy (or CT colonography).
• Bowel scope (one-off flexible sigmoidoscopy at 55) has been stopped.
• Screening FIT is not for people with symptoms - they should see their GP for a symptomatic FIT and referral.
• Higher-risk people (family history, syndromes, IBD) need their own surveillance programme instead of, or as well as, screening.
• Uptake is lowest in deprived areas, men, and people in their 50s - encourage participation.

↑ Back to index

Inherited Bowel Cancer Syndromes

• Lynch syndrome (hereditary non-polyposis colorectal cancer):
  • Genes: Autosomal dominant mutations in mismatch repair genes (MLH1, MSH2, MSH6, PMS2, EPCAM). The commonest inherited bowel cancer syndrome (about 1 in 300 people).
  • Cancers: Colorectal (often right-sided, younger age), endometrial, ovarian, stomach, small bowel, urinary tract, pancreas.
  • Found by: Testing all colorectal and endometrial cancers for MMR deficiency, then germline genetic testing.
  • Management:
    • Colonoscopy every 2 years (from 25 for MLH1 and MSH2; from 35 for MSH6 and PMS2).
    • Daily aspirin (NICE NG151 - reduces cancer risk).
    • Consider risk-reducing hysterectomy and removal of ovaries once the family is complete.
• Familial adenomatous polyposis (FAP):
  • Gene: Autosomal dominant APC mutation.
  • Features:
    • Hundreds to thousands of adenomas from the teens - cancer is almost certain by 40 without surgery.
    • Also duodenal adenomas (cancer risk - surveillance OGD), desmoid tumours, osteomas, dental problems, epidermoid cysts (Gardner syndrome), and CHRPE (pigmented spots on the retina).
  • Management:
    • Colonoscopy from about 12–14 years.
    • Prophylactic colectomy (usually late teens or twenties).
• MUTYH-associated polyposis: Autosomal recessive - tens to hundreds of polyps; often no family history.
• Peutz–Jeghers syndrome:
  • STK11 gene.
  • Pigmented freckles on the lips and mouth.
  • Hamartomatous polyps - cause intussusception and bleeding.
  • Raised risk of many cancers (breast, pancreas, GI).
• Juvenile polyposis: SMAD4 or BMPR1A - SMAD4 overlaps with hereditary haemorrhagic telangiectasia.
• Family history without a known syndrome (BSG 2019):
  • One first-degree relative under 50, or two at any age - a one-off colonoscopy at 55.
  • Stronger histories - colonoscopy every 5 years from 40 to 75.
  • Refer to clinical genetics if the history suggests a syndrome.

↑ Back to index

Vascular Bowel Disorders

• Angiodysplasia:
  • Small fragile blood vessels in the bowel wall, commonest in the right colon and small bowel in older people.
  • Causes iron deficiency anaemia or recurrent bleeding.
  • Linked to aortic stenosis (Heyde's syndrome - acquired von Willebrand deficiency; bleeding often stops after valve replacement), kidney failure and LVADs.
  • Treatment:
    • Argon plasma coagulation at endoscopy.
    • Iron (IV iron if oral fails).
    • Review anticoagulants.
    • Octreotide for recurrent cases.
• Chronic mesenteric ischaemia:
  • Atherosclerosis of the gut arteries (usually 2 or more of: coeliac axis, superior mesenteric, inferior mesenteric).
  • Pain after eating ("gut angina"), fear of food and weight loss in a smoker with vascular disease.
  • CT angiography.
  • Stenting or surgical bypass; it can progress to acute ischaemia.
• Ischaemic colitis - see the IBD chapter. Acute mesenteric ischaemia - see the Gastroenterology Emergencies chapter.
• Median arcuate ligament syndrome: Compression of the coeliac artery - rare cause of pain after eating in young people.

↑ Back to index

Haemorrhoids and Anal Fissure

Haemorrhoids (piles):

• What they are: Swollen vascular cushions in the anal canal. Linked to constipation, straining, pregnancy, and ageing.
• Symptoms:
  • Painless bright red bleeding on the paper or dripping into the pan, separate from the stool.
  • A lump; itching; mucus.
• Grades (internal haemorrhoids):
  • I - don't prolapse.
  • II - prolapse and return on their own.
  • III - need pushing back.
  • IV - permanently prolapsed.
• Treatment:
  • Fibre, fluids, no straining; topical soothing preparations (short courses of steroid creams).
  • Rubber band ligation for grade I–III.
  • Haemorrhoidal artery ligation, stapled haemorrhoidopexy, or haemorrhoidectomy for larger or recurrent haemorrhoids.
• Thrombosed external haemorrhoid: A sudden, very painful purple lump. Within 72 hours, consider excision; otherwise analgesia, ice and stool softeners (it settles over 1–2 weeks).
• Older patients with rectal bleeding still need assessment for cancer - don't assume piles.

Anal fissure:

• What it is: A tear in the anal lining, usually in the posterior midline, from hard stools.
• Symptoms: Sharp, tearing pain on opening the bowels that lasts for hours, with a little bright red blood.
• Acute (under 6 weeks) vs chronic (skin tag, exposed muscle fibres).
• Treatment:
  • Stool softeners, fibre and fluids; topical lidocaine.
  • GTN 0.4% ointment twice daily for 6–8 weeks (headache is common) or diltiazem 2% cream (off-label).
  • Botulinum toxin injection; lateral internal sphincterotomy (risk of incontinence).
• Atypical fissures (lateral, multiple, painless): Consider Crohn's disease, TB, HIV, syphilis, herpes and anal cancer.

↑ Back to index

Other Anorectal Conditions

• Perianal abscess: A painful, hot, throbbing swelling, with fever. Needs incision and drainage - antibiotics alone don't work. Many lead to a fistula.
• Fistula-in-ano:
  • A tract from the anal canal to the skin, with persistent discharge.
  • Linked to Crohn's, TB and HIV.
  • MRI to map it.
  • Treatment: Fistulotomy (simple), seton (complex - protects the sphincter).
• Pilonidal sinus: Hair in the natal cleft causing abscesses and sinuses in young hairy men. Drainage or excision.
• Pruritus ani:
  • Causes: Poor hygiene or over-washing, haemorrhoids, leakage of stool, threadworms (children), dermatitis, psoriasis, candida.
  • Treatment: Keep the area clean and dry; avoid scented products; short-course mild steroid.
• Rectal prolapse:
  • Full-thickness rectum through the anus - older women, chronic straining.
  • Mucus, bleeding, incontinence.
  • Surgery (abdominal rectopexy or perineal procedures).
• Faecal incontinence (NICE CG49):
  • Causes:
    • Obstetric sphincter injury.
    • Faecal impaction with overflow.
    • Diarrhoea.
    • Neurological disease.
    • Dementia.
  • Management:
    • Treat the cause.
    • Loperamide; bowel routines.
    • Pelvic floor exercises and biofeedback.
    • Transanal irrigation.
    • Sacral nerve stimulation; sphincter repair.
  • Ask about it - many people never mention it.
• Anal cancer:
  • Usually squamous cell carcinoma linked to HPV.
  • Higher risk in HIV, men who have sex with men, smokers, and immunosuppression.
  • Bleeding, a lump, pain, an ulcer.
  • Treated with chemoradiotherapy (often curative) rather than surgery.
• Proctalgia fugax: Brief, severe stabbing rectal pain, often at night, with no cause found - reassure.

↑ Back to index

Drug Reference Table