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IM16.{13-14,16-17} | Diarrheal Disorder Treatment — SDL Guide (Part 3)

Self-Assessment: Integrating Diarrhoeal Treatment Decisions

The following scenarios require you to integrate rehydration assessment, antibiotic selection (or withholding), anti-parasitic drug selection with correct dosing, and surgical decision-making. Work through each before reading the analysis — this is the application level that the NMC KH competency requires.

Scenario A: A 25-year-old returns from a wedding where many guests fell ill with sudden-onset profuse watery diarrhoea. He has passed 6 litres of rice-water stools in 8 hours and is now in the emergency department unable to drink due to vomiting. BP 70/40 mmHg, HR 150/min, skin pinch recoils in >3 seconds, sunken eyes, altered sensorium. What is the immediate management, and when is antibiotic appropriate?

Analysis: Severe dehydration (Plan C) with hypovolaemic shock. Immediate: IV Ringer's Lactate 100 mL/kg — first 30 mL/kg in 30 minutes as rapid bolus to restore perfusion pressure; then 70 mL/kg over 2.5 hours. Monitor: radial pulse, BP, capillary refill, urine output. When patient is alert and tolerating oral intake, switch to WHO ORS. Antibiotic: once stable and tolerating oral intake, give doxycycline 300 mg single dose (or azithromycin if resistant cholera or pregnancy). Do NOT give antibiotic in shock — rehydration is the life-saving intervention, not the antibiotic.

Scenario B: A 38-year-old man is diagnosed with intestinal amoebiasis after stool microscopy showing E. histolytica trophozoites with erythrophagocytosis. He has no hepatic tenderness or fever. He is started on metronidazole 400 mg TDS for 10 days and his symptoms resolve completely. Two weeks later he returns requesting a repeat stool examination to confirm cure before stopping treatment. What is the CORRECT treatment status, and what further action is required?

Analysis: Metronidazole has been completed (correct). However, the luminal amoebicide has NOT been given. The patient still carries intraluminal cysts that metronidazole does not eradicate. The correct action: prescribe diloxanide furoate 500 mg TDS × 10 days immediately. Do not wait for a stool examination to confirm cyst presence — the stool examination result does not change the management (even if cysts are not detected on a single examination, cyst excretion is intermittent and the luminal agent is always required after tissue treatment for amoebiasis). Explain: this second drug prevents relapse and stops transmission to household contacts.

Scenario C: A 55-year-old man with 10-year UC (pancolitis) has been on mesalamine maintenance and has had three corticosteroid courses in the past 18 months. His most recent colonoscopy showed high-grade dysplasia in a flat lesion in the sigmoid colon. He is otherwise well and has no acute symptoms. What is the recommended management?

Analysis: High-grade dysplasia in UC is an indication for elective colectomy — it is a precursor to colorectal carcinoma, and in the context of long-standing pancolitis, the entire colon is at risk. This is not urgent (no acute emergency), but should be planned promptly with surgical referral. The procedure of choice: total proctocolectomy with ileo-anal pouch anastomosis (J-pouch). The three corticosteroid courses in 18 months additionally indicate steroid dependence — another indication for surgical consideration even before dysplasia appeared, though dysplasia takes clinical priority now. Pre-operative preparation: stop/bridge immunosuppressants (per surgical team guidance), nutritional optimisation, patient education about ileostomy (temporary, while the pouch heals).