Bowel Habits
ABCs
- check vitals + RBS
- assess hydration + mental status
- establish IV access if unstable
diarrhea · red flags
don’t miss
- SBP < 90 / HR > 100 → shock
- fever > 38.5°C + bloody stool → infectious colitis / C. diff
- AMS + acidosis → sepsis / severe dehydration
- recent antibiotics → C. difficile
- immunocompromised → opportunistic infection
diarrhea · HPI & examination
- onset, frequency, volume; character: watery / fatty / bloody
- associated: fever, vomiting, abdominal pain
- PMH: IBD, malignancy, recent surgery; medications: antibiotics, PPIs, laxatives
- examination: hydration (dry mucosa, hypotension); abdomen (distension, tenderness); bowel sounds: hyperactive → gastroenteritis, absent → ileus / obstruction
diarrhea · management
- general: oral rehydration ± IV fluids; monitor stool output + hydration; stop offending medications
- constipation: lactulose 15–30 mL PO BD (bloating, flatulence, cramps); senna 7.5–15 mg PO nocte (cramps); macrogol (Movicol) 1–3 sachets/day; bisacodyl 5–10 mg PO/PR; glycerin / phosphate enema if impacted; opioid-induced → senna + osmotic laxative, reduce the opioid
- diarrhea: rehydration; loperamide 4 mg then 2 mg per loose stool (max 16 mg/day; avoid if infective / colitis / bloody)
- C. difficile: fidaxomicin 200 mg PO BID (preferred) or vancomycin 125 mg PO QID ×10 d; metronidazole 500 mg PO/IV TDS if unavailable; stop offending antibiotics; current regimens → empiric antibiotics
- severe bacterial colitis: ceftriaxone ± metronidazole; toxic megacolon / ischaemia → surgery
- investigations
- bloods: CBC, U&E
- stool: C. diff PCR, fecal leukocytes / calprotectin, O&P
- if unwell: lactate, ABG / VBG
call surgery STAT
- toxic megacolon, obstruction, ischemic colitis
call ICU STAT
- septic shock; severe acidosis / electrolyte derangement
cause-specific
| cause | management |
|---|---|
| C. difficile | Vancomycin 125 mg PO QID × 10 days |
| bacterial (severe) | Ceftriaxone ± Metronidazole |
| viral | supportive only |
| parasitic | targeted therapy (e.g. Metronidazole) |
| IBD flare | supportive ± steroids (GI input) |
constipation · red flags
don’t miss
- severe pain + vomiting + no flatus → obstruction
- distension + absent bowel sounds → ileus
- neurological deficit → spinal pathology
- weight loss + new onset → malignancy
constipation · HPI & examination
- duration, last bowel motion, flatus; pain, distension; post-op status
- medications: opioids, chemotherapy, diuretics
- examination: abdomen (distension, tenderness); rectal exam (impaction, bleeding); bowel sounds: normal q5–10 sec, absent → ileus, hyperactive → obstruction
constipation · management
- obstruction suspected
- NPO + NGT; IV fluids; labs CBC, RFT, lactate; imaging AXR / CT
- call Surgery STAT
- no obstruction
- mild: hydration + fiber + glycerin suppository
- moderate (> 48 hr): Movicol 1–2 sachets BID ± enema
- severe (> 72 hr / symptomatic): DRE → rule out impaction; if impacted → manual disimpaction, then suppository ± enema
- symptom control: pain → Buscopan or Paracetamol IV
escalation
- suspected obstruction → Surgery STAT
- clinical deterioration → escalate early
studying for the IM exam? the IM Rapid Review covers this in the same format. see the sample chapter.
Last reviewed · May 2026