Uro-Renal PoCUS: A Focused Approach to Flank Pain and Urinary Retention
Uro-renal point-of-care ultrasound can rapidly assess the kidneys and bladder for hydronephrosis, urinary retention, renal cysts, and other findings that may guide bedside decision-making. The original post highlights hydronephrosis, ureteric jets, bladder volume, and renal cysts as key areas of assessment.
The original post by SonoRay highlights hydronephrosis, ureteric jets, bladder volume, and renal cysts as key areas of assessment.
Flank pain? Urinary retention? Reach for the probe.
Uro-renal point-of-care ultrasound is a rapid bedside examination that can support the evaluation of suspected renal colic and urinary retention. It allows clinicians to assess the kidneys and bladder without ionizing radiation and integrate the findings with the patient’s overall clinical presentation.
Begin by scanning both kidneys in longitudinal and transverse planes. Comparing the two sides can help identify asymmetry and distinguish an abnormal collecting system from normal anatomical variants. Comparing the two sides can help identify asymmetry and distinguish an abnormal collecting system from normal anatomical variants. Clinicians performing uro-renal PoCUS should be familiar with the relevant scanning techniques and limitations, which are commonly addressed in POCUS courses for healthcare professionals.
Look for the following key findings:
Hydronephrosis
Hydronephrosis appears as anechoic dilation of the renal pelvis and calyces. In a patient with suspected renal colic, it may serve as a secondary sign of urinary tract obstruction because ureteral stones are not always directly visible on ultrasound.
Renal or Ureteral Stones
Stones may appear as bright, echogenic structures with posterior acoustic shadowing. Stones within the ureter can be difficult to identify, particularly when they are located away from the ureteropelvic or ureterovesical junctions.
Ureteric Jets
Colour Doppler may be used to look for intermittent urine flow entering the bladder from the ureteric openings. Ureteric jets can provide additional information, but they should be treated as an adjunct rather than interpreted in isolation.
Bladder Volume
Bladder ultrasound can help assess suspected urinary retention. Obtain transverse and sagittal images and use the machine’s volume function or the following formula: Bladder volume = 0.52 × depth × width × height
Renal Cysts
Renal cysts may appear as smooth, fluid-filled structures within or along the periphery of the kidney. They should be distinguished from hydronephrosis, which follows the branching pattern of the renal collecting system.
A normal bedside scan does not completely exclude early obstruction, a small ureteral stone, or another cause of abdominal or flank pain. PoCUS findings should always be interpreted alongside the history, examination, laboratory results, and need for further imaging.
Scan both kidneys.
Assess the bladder.
Interpret every finding in clinical context.
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