4.5 Functional, Malabsorptive & Infective Bowel Disorders, Anorectal Disease, Hernias & MASLD
Key Takeaways
NICE CG61 diagnoses IBS from at least 6 months of abdominal pain relieved by defecation or linked to altered bowel habit, plus 2 of straining or urgency, bloating, symptoms worse after eating, or mucus.
Before diagnosing IBS, check FBC, ESR or CRP, coeliac serology and (to exclude IBD in younger adults) faecal calprotectin, and assess NICE NG12 red flags.
Coeliac serology (tTG IgA with total IgA) is reliable only if the person has eaten gluten in more than one meal a day for at least 6 weeks before testing (NICE NG20).
A femoral hernia lies below and lateral to the pubic tubercle, has a high strangulation risk and needs urgent surgical referral.
Metabolic dysfunction-associated steatotic liver disease (MASLD) replaced the term NAFLD in 2023; FIB-4 and ELF or elastography identify advanced fibrosis.
Functional, Malabsorptive & Infective Bowel Disorders, Anorectal Disease, Hernias & MASLD
Irritable Bowel Syndrome (IBS)
IBS is a disorder of gut-brain interaction, common in young women.
Diagnosis (NICE CG61)
Consider IBS if there has been abdominal pain or discomfort for at least 6 months that is relieved by defecation or associated with altered stool frequency or form, plus at least 2 of:
- altered stool passage (straining, urgency, incomplete evacuation)
- abdominal bloating, distension or hardness
- symptoms made worse by eating
- passage of mucus
First-line tests: full blood count, ESR or CRP, and coeliac serology; faecal calprotectin helps distinguish IBD from IBS in adults when cancer is not suspected. NICE advises not routinely doing ultrasound, colonoscopy, thyroid tests or hydrogen breath tests when the criteria are met.
Warning
Red Flags Exclude a Simple IBS Label: age over 50–60 with a new change in bowel habit, rectal bleeding, unintentional weight loss, anaemia, a mass, nocturnal symptoms, or a family history of bowel or ovarian cancer need investigation under NICE NG12 (FIT, endoscopy, CA125 in women with bloating).
Management
- Diet and lifestyle: regular meals, adequate fluid, reduce insoluble fibre, caffeine, alcohol and fizzy drinks; soluble fibre (ispaghula, oats) for constipation; a low-FODMAP diet only with a trained dietitian.
- Medicines by symptom: antispasmodics (mebeverine, hyoscine) for pain; loperamide for diarrhoea; laxatives other than lactulose (which causes bloating) for constipation.
- Second-line: low-dose tricyclic antidepressant (for example amitriptyline 5–10 mg at night), then an SSRI if a TCA does not help.
- Psychological therapies (CBT, hypnotherapy) for refractory symptoms.
Coeliac Disease
An immune-mediated enteropathy triggered by gluten in people with HLA-DQ2 or DQ8.
- Presentations: diarrhoea, bloating, weight loss, iron-deficiency anaemia, fatigue, faltering growth in children, mouth ulcers, raised liver enzymes, osteoporosis, and dermatitis herpetiformis (itchy blisters on the extensor surfaces).
- Who to test: people with these features and those with type 1 diabetes, autoimmune thyroid disease, Down's or Turner syndrome, IBS symptoms, or a first-degree relative with coeliac disease.
- Testing (NICE NG20): tTG IgA with total IgA; if IgA-deficient, use IgG-based tests. The person must have eaten gluten in more than one meal a day for at least 6 weeks beforehand. Adults with positive serology are referred for duodenal biopsy (villous atrophy, crypt hyperplasia, intraepithelial lymphocytes); a no-biopsy pathway is used for some children with very high titres.
- Management: lifelong gluten-free diet with dietitian support, annual review, bone health assessment, and pneumococcal vaccination because of hyposplenism. Untreated disease increases the risk of enteropathy-associated T-cell lymphoma.
Other causes of malabsorption include chronic pancreatitis (steatorrhoea; pancreatic enzyme replacement), bile acid malabsorption (after ileal resection or cholecystectomy), lactose intolerance and small bowel bacterial overgrowth.
Infective Gastroenteritis
| Organism | Clues |
|---|---|
| Norovirus | Outbreaks of vomiting and diarrhoea in hospitals, care homes and cruise ships; very infectious |
| Campylobacter | Most common bacterial cause in the UK; undercooked poultry; bloody diarrhoea, abdominal pain; linked to Guillain-Barré syndrome |
| Salmonella | Eggs and poultry; fever, diarrhoea |
| Shiga toxin-producing E. coli (O157) | Bloody diarrhoea; risk of haemolytic uraemic syndrome in children; avoid antibiotics and antimotility drugs |
| Staphylococcus aureus / Bacillus cereus | Pre-formed toxin: vomiting within 1–6 hours (B. cereus with reheated rice) |
| Giardia lamblia | Travellers, prolonged diarrhoea, bloating, steatorrhoea; metronidazole |
| Clostridioides difficile | After antibiotics; see section 14.4 |
Most cases need oral rehydration only. Send stool culture if there is blood, severe or prolonged illness, recent travel, immunosuppression or an outbreak. Suspected food poisoning is notifiable. People with diarrhoea or vomiting should stay off work or school until 48 hours after symptoms stop, which is especially important for food handlers and healthcare workers.
Anorectal Disorders
- Haemorrhoids: painless bright red bleeding on the paper or coating the stool, with prolapse. Internal haemorrhoids are graded I–IV. Treat with fibre, fluids and topical preparations; rubber band ligation for persistent grade I–III. A thrombosed external haemorrhoid is very painful; excision is considered within about 72 hours, otherwise ice, analgesia and stool softeners.
- Anal fissure: sharp pain on defecation lasting minutes to hours, with bright red blood; a midline posterior tear. Chronic fissures (more than 6 weeks) are treated with topical glyceryl trinitrate 0.4% for 6–8 weeks (topical diltiazem is an alternative), with stool softeners; refer if they do not heal (botulinum toxin or sphincterotomy). Lateral or multiple fissures suggest Crohn's disease, TB, HIV or malignancy.
- Perianal abscess: throbbing pain, swelling and fever; needs urgent incision and drainage (antibiotics alone are inadequate). Recurrent abscesses suggest a fistula-in-ano or Crohn's disease.
- Pilonidal sinus: natal cleft sinus or abscess in young hairy men; drainage, then definitive surgery.
- Anal cancer: usually squamous cell carcinoma linked to HPV; an unexplained anal mass or ulcer needs a suspected cancer pathway referral.
Abdominal Wall Hernias
| Hernia | Key Features |
|---|---|
| Indirect inguinal | Most common hernia; through the deep inguinal ring, lateral to the inferior epigastric vessels; can enter the scrotum; common in men and children |
| Direct inguinal | Through the posterior wall (Hesselbach's triangle), medial to the inferior epigastric vessels; older men |
| Femoral | Below and lateral to the pubic tubercle; more common in women; high risk of strangulation, so needs urgent surgical referral |
| Umbilical (infant) | Most close spontaneously in early childhood |
| Paraumbilical / incisional | Adults, obesity, previous surgery |
An incarcerated hernia is irreducible; a strangulated hernia (tender, red, irreducible lump with bowel obstruction or systemic upset) is a surgical emergency. Inguinal hernias in infants are repaired promptly because of the incarceration risk.
Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD)
In 2023, international liver societies replaced the term non-alcoholic fatty liver disease (NAFLD) with MASLD (steatosis plus at least one cardiometabolic risk factor) and non-alcoholic steatohepatitis with MASH. MASLD is the commonest cause of abnormal liver tests in the UK and is linked to obesity, type 2 diabetes, hypertension and dyslipidaemia.
- Assess fibrosis: calculate the FIB-4 score from routine blood tests; if indeterminate or high, use the Enhanced Liver Fibrosis (ELF) test or transient elastography (FibroScan). Advanced fibrosis needs hepatology referral and surveillance for cirrhosis and hepatocellular carcinoma.
- Management: sustained weight loss of 7–10%, physical activity, Mediterranean-style diet, limiting alcohol, and treating diabetes, blood pressure and lipids (statins are safe and should not be withheld). GLP-1 receptor agonists help weight and liver fat.
Rectal Prolapse
Protrusion of the rectum through the anus, most often full-thickness prolapse in older women with chronic straining and weak pelvic floor muscles; in children it can be the first sign of cystic fibrosis or chronic constipation. Patients describe a lump on straining, mucus discharge, bleeding and faecal incontinence. A prolapse that cannot be reduced or looks dusky needs urgent surgical review; elective treatment is surgical (for example rectopexy).
A 26-year-old woman has 8 months of crampy lower abdominal pain relieved by opening her bowels, alternating loose and hard stools, and bloating that is worse after meals. She has no weight loss or rectal bleeding, and examination is normal. Which set of tests is most appropriate before diagnosing irritable bowel syndrome?
Faecal immunochemical test, CA125 and pelvic ultrasound
Colonoscopy, abdominal ultrasound and thyroid function tests
FBC, ESR or CRP, coeliac serology and faecal calprotectin
Lactose hydrogen breath test and CT of the abdomen and pelvis
A 34-year-old man has iron-deficiency anaemia and bloating. He started a gluten-free diet 2 months ago because he felt better without bread, and his tTG IgA is negative with a normal total IgA. What is the most appropriate next step?
Test for HLA-DQ2 and DQ8 and diagnose coeliac disease if positive
Arrange immediate duodenal biopsy while he stays gluten-free
Exclude coeliac disease and continue the gluten-free diet
Eat gluten in more than one meal daily for 6 weeks, then retest
A 71-year-old woman has a tender, irreducible lump in her right groin below and lateral to the pubic tubercle. She has vomited twice and has not passed flatus for 12 hours. What is the most appropriate management?
Emergency surgical admission for repair
Routine surgical outpatient referral
Attempt firm manual reduction and discharge
Ultrasound in 2 weeks to confirm the diagnosis
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