In an adult with gross hematuria, severe colicky flank pain, and sandy urine but a non‑contrast CT scan shows no stones, what is the appropriate next step in evaluation and management?

Evaluation and Management of Suspected Renal Colic with Negative Non-Contrast CT

When a non-contrast CT shows no stones in a patient with gross hematuria, severe colicky flank pain, and sandy urine, proceed with CT abdomen and pelvis with IV contrast to identify alternative diagnoses, as 15% of patients with flank pain and negative urinalysis without stone history have important alternative diagnoses best characterized by contrast-enhanced imaging. 1

Understanding the Clinical Scenario

Your patient presents with classic stone symptoms but imaging shows no calculi—this creates a diagnostic dilemma requiring systematic evaluation:

Why Stones Might Be Missed

• Small or recently passed stones: Non-contrast CT has 97% sensitivity for stones, but very small stones (<2mm) or stones that passed between symptom onset and imaging may not be visualized 1
• Radiolucent stones: While rare, some matrix stones or certain medication-related stones may be difficult to visualize on non-contrast CT 2
• Timing of hydronephrosis: Secondary signs of obstruction may not develop in the first 2 hours of presentation, leading to false-negative findings 3

The Hematuria Paradox

The presence of gross hematuria does NOT confirm stones and its absence does NOT exclude them:

• 11-19% of patients with confirmed ureteral stones have no hematuria on urinalysis 4, 5
• Conversely, 51% of patients WITHOUT stones have hematuria present 5
• The combined absence of both hydronephrosis AND hematuria has a 96.4% negative predictive value for ureteral stones 3—but your patient HAS hematuria, so stones remain possible

Next Steps in Evaluation

Primary Recommendation: CT Abdomen/Pelvis WITH IV Contrast

Obtain CT with IV contrast to evaluate for alternative diagnoses 1:

• In patients with flank pain and negative urinalysis without stone history, 15% have diagnoses best characterized by contrast-enhanced CT 1
• Contrast imaging can identify:
  • Vascular emergencies: Renal infarction, renal vein thrombosis, subcapsular hematoma (Page kidney) 6
  • Infectious causes: Pyelonephritis, perinephric abscess, pyonephrosis 1
  • Malignancies: Renal cell carcinoma, urothelial carcinoma
  • Other urologic pathology: Papillary necrosis, ureteropelvic junction obstruction

Consider Point-of-Care Ultrasound (POCUS)

If not already performed, bedside ultrasound can provide critical information 7:

• Moderate-to-severe hydronephrosis on POCUS is 94.4% specific for obstructing stone 7
• If moderate-to-severe hydronephrosis is present despite negative CT, this suggests either:
  • A stone passed between imaging studies
  • Alternative obstruction (blood clot, papillary tissue, external compression)
• Absence of hydronephrosis does NOT rule out stones (NPV only 65-87%) 3, 7

Alternative Diagnoses to Consider

Given the symptom complex with negative stone imaging, actively evaluate for:

1. Hemorrhagic cystitis with ureteral clot obstruction: Blood clots can acutely obstruct the distal ureter, causing hydronephrosis and flank pain that mimics stones 8

2. Page kidney: Subcapsular hematoma causing renal compression, presenting with flank pain, hematuria, and hypertension 6

3. Renal infarction: Severe flank pain with hematuria, often with elevated LDH and minimal hydronephrosis

4. Papillary necrosis: "Sandy urine" may represent sloughed papillary tissue rather than stone fragments

Management Algorithm

Immediate Actions:

• Pain control: Manage symptoms regardless of imaging findings
• Check vital signs: Hypertension suggests Page kidney or renal vascular pathology 6
• Repeat urinalysis: Examine for dysmorphic RBCs (glomerular disease), WBC casts (pyelonephritis), or tissue fragments

Imaging Decision Tree:

1. If hydronephrosis present on initial CT → Proceed with contrast-enhanced CT to characterize cause 1

2. If no hydronephrosis and symptoms persist → Consider:

   • POCUS to reassess for interval development of hydronephrosis 7
   • Contrast-enhanced CT for alternative diagnoses 1

3. If symptoms resolve spontaneously → Likely passed stone; consider outpatient follow-up with KUB radiography or ultrasound 1

Critical Pitfalls to Avoid

• Do not assume absence of stones on CT excludes urolithiasis: 13% of patients with negative CT have stone-related findings requiring management 1

• Do not rely solely on hematuria: Its presence or absence has insufficient predictive value for stone disease 4, 5

• Do not delay contrast imaging when infection is suspected: CT cannot reliably distinguish pyonephrosis from simple hydronephrosis without contrast 1

• Do not dismiss "sandy urine" as definitively representing stones: This may indicate papillary necrosis, hemorrhagic debris, or other pathology requiring different management

When to Involve Urology

Urgent consultation indicated for 7:

• Moderate-to-severe hydronephrosis with suspected obstruction
• Signs of infection with obstruction (requires emergent decompression)
• Alternative diagnoses requiring surgical intervention (e.g., significant subcapsular hematoma)