How can I differentiate between renal colic and other causes of acute abdominal pain in a primary care setting?

In a primary care setting, differentiating renal colic from other causes of acute abdominal pain relies primarily on clinical assessment supported by targeted investigations. Key clinical features suggestive of renal colic include sudden onset of severe, colicky flank pain radiating to the groin, often accompanied by nausea or vomiting, and sometimes visible haematuria. The pain is typically severe and intermittent, reflecting ureteric spasm due to stone obstruction. Systemic signs such as fever or sepsis suggest alternative or complicated diagnoses and warrant urgent hospital referral. ¹,²

Physical examination may reveal flank tenderness but usually lacks peritoneal signs, which are more indicative of other acute abdominal pathologies. Absence of abdominal guarding or rebound tenderness helps differentiate renal colic from surgical causes like appendicitis or cholecystitis. (Schwarzenbach and Jenzer, 2012)

Urinalysis can support the diagnosis by detecting microscopic haematuria, although its absence does not exclude renal colic. (Schwarzenbach and Jenzer, 2012) In contrast, signs of infection in urine or blood tests may indicate pyelonephritis or other causes.

When the diagnosis is uncertain or if the patient is at risk of complications, urgent imaging is recommended within 24 hours. For adults, low-dose non-contrast CT is the preferred modality due to its high sensitivity and specificity for detecting stones and assessing obstruction. For pregnant women, children, and young people, ultrasound is the first-line imaging to avoid radiation exposure, with CT reserved if ultrasound is inconclusive. ¹,²,³

Other causes of acute abdominal pain, such as gastrointestinal, gynecological, or vascular conditions, often present with different pain characteristics, associated symptoms, or examination findings. For example, persistent abdominal pain with systemic features or masses may require cancer pathway referral or other urgent investigations. ⁴

In summary, the differentiation in primary care hinges on a detailed history focusing on pain characteristics, associated symptoms, physical examination findings, urinalysis, and timely imaging when indicated. Immediate pain relief with NSAIDs is appropriate if renal colic is suspected, but referral is necessary if systemic infection, risk factors for kidney injury, or diagnostic uncertainty exist. ¹,²,³ (Schwarzenbach and Jenzer, 2012)