From the Guidelines
For this patient with increased urinary frequency and abdominal pain radiating from the suprapubic region to bilateral flanks upon urination, the most appropriate diagnostic approach is to perform a Noncontrast CT (NCCT) of the abdomen and pelvis. This recommendation is based on the latest evidence from the Journal of the American College of Radiology, 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 without known prior stone disease 1. The patient's symptoms, including increased frequency of urination and abdominal pain, are consistent with possible obstructive urolithiasis, and NCCT can reliably characterize the location and size of an offending ureteral calculus, identify complications, and diagnose alternative etiologies of abdominal pain.
Key points to consider in this diagnosis include:
- The patient's symptoms of increased urinary frequency and abdominal pain radiating to the flanks are consistent with possible obstructive urolithiasis
- NCCT is the most sensitive and specific imaging modality for detecting ureteral stones and identifying complications such as hydronephrosis
- Ultrasound may have a role in evaluating for signs of obstruction, but it is less sensitive than NCCT for detecting stones
- The patient's daily water intake of 48 ounces is relatively low, which may contribute to the development of kidney stones
While other diagnostic tests, such as Post-Void Residual Urine (PVRU) measurement, may be useful in evaluating the patient's lower urinary tract symptoms, NCCT is the most appropriate initial diagnostic step given the clinical presentation of possible obstructive urolithiasis. Additionally, a study published in 2024 found that CT abdomen and pelvis without IV contrast can be useful in evaluating symptomatic patients with hydronephrosis of unknown cause, and that hydronephrosis can help predict the likelihood of ureteral stone on subsequent CT 1. However, NCCT remains the test of choice for initial evaluation of patients with suspected stone disease, and it is the most appropriate diagnostic approach for this patient.
From the Research
Diagnostic Approach
The patient's symptoms of increased frequency of urination and abdominal pain radiating from the suprapubic region to bilateral flanks upon urination may indicate a urinary tract issue. To diagnose the cause of these symptoms, the following diagnostic approaches can be considered:
- Computed Tomography (CT) of the abdomen, which is usually appropriate for the initial imaging of many urinary tract diseases 2
- Post-voiding residual volume (PVR) assessment, which can help identify patients at risk for bacteriuria and urinary tract infection 3
- Uroflowmetry (UF) and ultrasound (US) to evaluate lower urinary tract dysfunction (LUTD) 4
- Pressure-flow studies (PFS) to diagnose bladder outlet obstruction (BOO) and detrusor underactivity (DUA) 5
Diagnostic Tests
The following diagnostic tests can be used to evaluate the patient's symptoms:
- CT urography (CTU) to visualize the upper and lower urinary tract and detect urinary tract malignancies 2
- Urinalysis and culture to rule out infection 6
- Renal function tests to assess damage to the upper tracts 6
- Post-void residual urine ratio (PVR-R) to assess pathological bladder emptying 5
Considerations
When evaluating the patient's symptoms, the following considerations should be taken into account:
- The patient's daily water intake of 48 ounces may be contributing to the frequency of urination
- The patient's symptoms of abdominal pain and radiating pain to the bilateral flanks may indicate a more serious underlying condition, such as a urinary tract infection or malignancy
- The patient's age and medical history should be taken into account when selecting diagnostic tests and developing a treatment plan 6