Does flank pain suggest bladder stones?

Flank Pain Does NOT Signify Bladder Stones

Flank pain is a classic symptom of kidney stones (nephrolithiasis) or ureteral stones, not bladder stones. Bladder stones typically present with suprapubic pain, dysuria, urinary frequency, and interrupted urinary stream—not flank pain. 1

Understanding the Anatomic Distinction

• Flank pain arises from the kidney or ureter due to obstruction, distension of the collecting system, and ureteral hyperperistalsis caused by stones at these levels. 1
• The pain is characteristically colicky, wave-like, and severe, independent of body position, often radiating to the groin or genitals with abrupt onset. 2
• Bladder stones cause lower abdominal (suprapubic) discomfort, not flank pain, because the bladder is located in the pelvis, far below the anatomic region of the flanks. 1

Why This Distinction Matters Clinically

Diagnostic Implications

• Non-contrast CT of the abdomen and pelvis is the gold standard for evaluating flank pain, with 97–100% sensitivity and specificity for detecting kidney and ureteral stones. 1, 2
• CT imaging identifies the stone location (kidney, ureter, or bladder) and reveals alternative diagnoses in approximately one-third of patients presenting with flank pain. 2
• Hematuria is present in only 77% of patients with urolithiasis; more than 20% of confirmed stone cases have negative urinalysis, so absence of blood does not exclude stones. 2, 3

Management Differences

• Ureteral stones <5 mm typically pass spontaneously with conservative management including NSAIDs and hydration. 1, 4
• Stones >5 mm or causing complete obstruction may require endoscopic intervention (ureteroscopy, percutaneous nephrolithotomy, or shock wave lithotripsy). 1, 4
• Bladder stones are managed differently, often requiring cystoscopic removal or open cystolithotomy, and do not present with the acute colicky flank pain typical of upper urinary tract stones. 1

Common Pitfalls to Avoid

• Do not assume all lower abdominal or pelvic pain is from bladder stones; the anatomic location of pain is the key distinguishing feature. 2
• Do not confuse flank pain with suprapubic pain; flank pain localizes to the costovertebral angle and lateral abdomen, while bladder pathology causes midline lower abdominal discomfort. 1, 2
• Do not delay imaging based on negative urinalysis alone; proceed with non-contrast CT when clinical suspicion for urolithiasis remains high. 2, 4

Red Flags Requiring Urgent Evaluation

• Fever, chills, or signs of systemic infection suggest obstructive pyelonephritis or urosepsis and mandate immediate hospitalization, IV antibiotics, and possible urologic decompression. 2, 4
• Hemodynamic instability or shock requires emergent evaluation. 2
• Solitary kidney with obstruction is a urologic emergency. 2
• Inability to urinate or decreased urine output warrants urgent assessment. 2

Alternative Diagnoses to Consider with Flank Pain

When imaging reveals no stones, consider:

• Acute pyelonephritis (fever, costovertebral angle tenderness, pyuria). 4, 5
• Perinephric abscess (pain worsening with external pressure). 6
• Left-sided colonic diverticulitis (mimics renal colic; CT shows pericolic fat stranding). 2
• Pelvic congestion syndrome in women (dilated pelvic veins on contrast-enhanced imaging). 2
• Ectopic pregnancy in women of reproductive age (always obtain beta-hCG before imaging). 2, 4
• Musculoskeletal pain (worsens with movement or prolonged static positioning, unlike classic renal colic). 2