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Suspected renal colic in pregnancy — MSRA MCQ

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ModerateNephrologySuspected renal colic in pregnancyMSRA

A 31-year-old woman who is 26+2 weeks pregnant presents to an urgent GP assessment service with sudden severe left-sided loin pain radiating to the groin. The pain began 3 hours ago, is colicky, and she has vomited once. She has no vaginal bleeding, uterine tightening, dysuria, fever or rigors. Her temperature is 36.8°C, pulse 88 bpm and BP 118/72 mmHg. There is left renal angle tenderness but no abdominal guarding. Urine dipstick shows blood 3+, protein negative, nitrites negative and leucocytes negative. Her creatinine is 62 micromol/L and CRP is 4 mg/L. After initial analgesia, which is the most appropriate next diagnostic investigation?

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Correct answer: A — Arrange urgent renal tract ultrasound within 24 hours

This presentation is strongly suggestive of renal colic: acute colicky loin-to-groin pain with haematuria, without features suggesting urinary infection, sepsis, acute kidney injury or an obstetric cause. NICE recommends urgent imaging within 24 hours for adults with suspected renal colic. Although low-dose non-contrast CT is the first-line investigation for most non-pregnant adults, pregnancy is the key discriminator: ultrasound should be used instead of CT to avoid ionising-radiation exposure. A is the usual first-line test for a non-pregnant adult and is therefore an attractive distractor, but CT is not the recommended initial imaging modality in pregnancy. B has limited diagnostic performance for ureteric stones and exposes the fetus to radiation. C avoids ionising radiation and may occasionally be considered in specialist practice when diagnostic uncertainty persists, but it is not NICE first-line imaging for suspected renal colic in pregnancy. D inappropriately delays imaging despite a convincing presentation; normal inflammatory markers and renal function reduce the likelihood of infected obstruction but do not remove the need to establish the diagnosis promptly. Urgent ultrasound is therefore the single best next investigation.

Reference: NICE NG118: Renal and ureteric stones: assessment and management, recommendation 1.1.1 (Published 8 January 2019; last reviewed 26 February 2021) — https://www.nice.org.uk/guidance/ng118/chapter/Recommendations