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Renal ultrasound
From WikEM
Contents
Background
- Bedside renal ultrasound has accepted use in the diagnosis of nephrolithiasis
- In comparison of diagnosis by CT vs. U/S (by EP) vs. U/S (by radiologist):[1]
- No difference in rate of missed high-risk diagnoses that resulted in complications (pyelo/sepsis/diverticular abscess)
- No difference in rate of serious adverse events, pain scores, return emergency department visits, or hospitalizations
Indications
- Flank pain
- Suspected nephrolithiasis
Technique
- Select probe
- Curvilinear/large convex probe (phased array probe may substitute)
- Location
- Right kidney
- Patient supine
- Probe in the right lower intercostal space in the midaxillary line
- Left kidney
- Patient supine or right lateral decubitus
- Probe in the lower intercostal space on the posterior axillary line
- More cephalad and posterior than when visualizing the right kidney
- Right kidney
- Scan entire kidney (through liver)
- Longitudinal (long axis) and transverse (short axis) views
- Scan the bladder
Findings
- Hydronephrosis
- Mild: Distention of collecting system
- Moderate: Dilation of collecting system, rounding of calyces
- Severe: Dilated renal calyces and cortical thinning[2]
- “Bear claw” appearance
- Represents severe obstructive uropathy
Images
Normal
No hydronephrosis
Abnormal
Mild hydro
Moderate hydro
Severe hydro
Pearls and Pitfalls
- Renal cysts can sometimes be mistaken for hydronephrosis
- Cysts are typically single, circular, and arise in the periphery of the kidney
- They can be multiple as in polycystic kidney disease
- Patients that are overhydrated, pregnant, or with a full-bladder may have mild hydronephrosis bilaterally without obstruction
- Underhydrated patients may not have hydronephrosis on initial renal scanning, despite obstruction
Documentation
Normal Exam
A bedside ultrasound was conducted to assess for hydronephrosis with clinical indication of left/right flank pain. The left kidney, right kidney, and bladder were identified in the transverse and sagittal plane. There was no hydronephrosis identified.
Abnormal Exam
A bedside ultrasound was conducted to assess for hydronephrosis with clinical indication of left/right flank pain. The left kidney, right kidney, and bladder were identified in the transverse and sagittal plane. There was mild/moderate/severe hydronephrosis identified on the left/right.
Clips
Normal
Abnormal
Mild hydro
Moderate hydro
Severe hydro
Pitfall
Nonobstructing stone
Using color flow to determine vasculature vs hydro
