What diagnostic tests would be ordered for a patient presenting with left flank pain, possibly indicating Impaired renal function or nephrolithiasis (kidney stones)?

From the Guidelines

For a patient presenting with left flank pain, the most appropriate initial diagnostic test is a noncontrast CT (NCCT) scan of the abdomen and pelvis, as it is highly sensitive for detecting kidney stones and can help identify alternative etiologies of abdominal pain. This recommendation is based on the most recent and highest quality study available, which suggests that NCCT is the imaging study of choice for initial evaluation of patients with acute onset of flank pain and suspicion of stone disease 1.

Diagnostic Approach

The diagnostic approach for a patient with left flank pain should include:

• Urinalysis to check for blood, protein, or signs of infection
• Complete blood count and comprehensive metabolic panel to assess for infection markers, kidney function, and electrolyte imbalances
• Imaging studies, starting with NCCT, which can reliably characterize the location and size of an offending ureteral calculus, identify complications, and diagnose alternative etiologies of abdominal pain 1
• Ultrasound may have a role in evaluating for signs of obstruction, especially in patients who cannot undergo CT scanning
• If infection is suspected, urine culture would be ordered to identify specific pathogens

Imaging Studies

Imaging studies are crucial in diagnosing the underlying cause of left flank pain.

• NCCT is the preferred initial imaging study due to its high sensitivity for detecting kidney stones and its ability to identify alternative etiologies of abdominal pain 1
• CT abdomen and pelvis with IV contrast may be used to evaluate other etiologies of flank pain, but it is not the first-line test for suspected stone disease 1
• Ultrasound may be used as an alternative to CT scanning, especially in pregnant patients or those who cannot undergo CT scanning

Pain Management

Pain management is an important aspect of treating a patient with left flank pain.

• NSAIDs like ibuprofen (400-600mg every 6 hours) may be used to manage pain
• Opioid analgesics may be used if the pain is severe, while awaiting diagnosis
• The goal of pain management is to provide relief while awaiting diagnosis and treatment of the underlying cause of the pain.

From the Research

Diagnostic Tests for Left Flank Pain

The following diagnostic tests may be ordered for a patient presenting with left flank pain, possibly indicating impaired renal function or nephrolithiasis (kidney stones):

• Unenhanced helical CT (UHCT) scan to detect ureteral stones with high sensitivity and specificity, regardless of size, location, and chemical composition 2, 3
• Intravenous urography (IVU) to evaluate the urinary tract and detect ureteral calculi, although it may be hampered by poor quality due to lack of bowel preparation, nephrotoxicity of contrast agents, and significant radiation exposure 2
• Ultrasonography (US) to detect pyeloureteral dilatation, direct visualization of stones, and the absence of ureteral ejaculation, with a sensitivity to detect ureteral dilatation as high as 96% 2
• Plain abdominal radiographs to detect kidney stones, although it may not be as sensitive as other imaging modalities 2, 4
• CT scan of the abdominal and pelvis without contrast to evaluate the kidneys and detect any abnormalities, such as multicystic dysplastic kidney or perinephric stranding 5, 6
• Voiding cystouretrogram to evaluate the urinary tract and detect any abnormalities, such as vesicoureteral reflux (VUR) 5
• Dimercaptosuccinic acid scan to evaluate the renal function and detect any abnormalities, such as scarring or damage to the renal parenchyma 5

Additional Tests

Additional tests may be ordered to evaluate the patient's symptoms and detect any underlying conditions, such as:

• Urinalysis to detect infection, blood, or other abnormalities in the urine 5, 6, 4
• Urine culture to detect any bacterial infections in the urine 5
• Blood tests to evaluate the patient's renal function and detect any underlying conditions, such as hypertension or electrolyte imbalances 6