Absence of red blood cells on urinalysis rules out kidney stones.

• A. True
• B. Cannot be ruled out
• C. False
• D. Only with imaging

Answer: (C)

Hematuria is common with kidney stones, but its absence does not exclude stones. Stones can cause severe flank or groin pain from obstruction or ureteral irritation even when no blood is detected in the urine at the time of testing. Bleeding can be intermittent or microscopic, so a single urinalysis may miss it. Because of this, a normal urinalysis cannot be used to rule out stones. If clinical suspicion remains high, imaging is needed to confirm the diagnosis, with non-contrast CT being the most sensitive test and ultrasound used in pregnancy or specific situations.