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

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.