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Ureteric stone causing renal colic in the third trimester of pregnancy — MSRA MCQ

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HardNephrolithiasisUreteric stone causing renal colic in the third trimester of pregnancyMSRA

A 30-year-old woman who is 31+5 weeks pregnant presents to an urgent treatment centre with abrupt severe left-sided colicky flank pain and vomiting. She has no vaginal bleeding, uterine activity, dysuria or fever. Her temperature is 36.9°C, heart rate 92 beats/minute and blood pressure 118/70 mmHg. Urinalysis shows blood 3+ but nitrites and leucocytes are negative. Her creatinine is 62 micromol/L. Renal ultrasound performed urgently demonstrates mild left hydronephrosis and a 6 mm distal ureteric calculus. She has no history of peptic ulcer disease, renal disease, opioid use or drug allergy. What is the most appropriate immediate analgesic treatment?

Educational content. Not a substitute for clinical judgement or local policy.

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Correct answer: C — Administer intravenous paracetamol

This is uncomplicated renal colic in the third trimester: ultrasound has demonstrated a ureteric stone, while the absence of fever, pyuria, haemodynamic instability and renal impairment makes infected obstruction or urgent decompression unlikely at this point. NSAIDs would normally be first-line for renal colic, but diclofenac is contraindicated in the third trimester because prostaglandin inhibition can cause fetal cardiopulmonary and renal toxicity and can delay labour. NICE therefore recommends intravenous paracetamol when NSAIDs are contraindicated or inadequate. Opioids are not the next routine step. NICE advises considering them only when both NSAIDs and intravenous paracetamol are contraindicated or have failed to provide sufficient analgesia. Oral morphine is additionally unsuitable in a vomiting patient when prompt, reliable analgesia is required. Hyoscine butylbromide is an antispasmodic; NICE specifically advises against antispasmodics for suspected renal colic. Intravenous paracetamol is therefore the appropriate immediate analgesic, with reassessment and escalation to an opioid only if pain remains uncontrolled.

Reference: Renal and ureteric stones: assessment and management (NG118) — Recommendations (2019; guideline PDF updated 2026) — https://www.nice.org.uk/guidance/ng118/chapter/Recommendations Diclofenac sodium Dexcel XL 100 mg prolonged-release tablets — Summary of Product Characteristics (2026) — https://www.medicines.org.uk/emc/product/2662/smpc