What are the recommended initial investigations for a patient presenting with renal colic?

Guideline-aligned answer with reasoning, red flags and references. Clinically reviewed by Dr Kola Tytler MBBS CertHE MBA MRCGP.

Posted: 16 August 2025 Guideline-Aligned (High Confidence) Clinically Reviewed
Dr Kola Tytler MBBS CertHE MBA MRCGPClinical Lead • iatroX

Recommended initial investigations for a patient presenting with renal colic include urgent imaging and assessment of clinical risk factors.

  • For most adults, urgent (within 24 hours) low-dose non-contrast CT is recommended to confirm the diagnosis and assess the likelihood of spontaneous stone passage.
  • If the patient is a pregnant woman, ultrasound should be offered instead of CT to avoid radiation exposure.
  • For children and young people, ultrasound is the first-line imaging investigation, with low-dose non-contrast CT considered only if diagnosis remains uncertain after ultrasound.
  • Immediate hospital admission and further investigations are warranted if the patient has signs of systemic infection or sepsis, is at increased risk of acute kidney injury (e.g., pre-existing chronic kidney disease, solitary or transplanted kidney, or suspected bilateral obstructing stones), or cannot tolerate oral fluids due to nausea/vomiting.

These imaging investigations are essential to confirm the diagnosis, evaluate stone size and location, and identify any anatomical or medical conditions associated with recurrent stones.

Educational content only. Always verify information and use clinical judgement.