Documentation of Normal Bilateral Renal Artery/Venous Duplex Ultrasound
Document this study as a technically adequate examination showing no hemodynamically significant renal artery stenosis bilaterally, with normal kidney sizes and patent renal veins, while explicitly noting the technical limitation of body habitus that may reduce sensitivity for detecting stenosis.
Essential Documentation Components
Primary Findings to Document
State explicitly "No hemodynamically significant renal artery stenosis" rather than just "no stenosis," as hemodynamically significant stenosis is defined as ≥50-60% diameter reduction with clinical indicators 1, 2
Document the renal-aortic ratios (RAR): Right RAR 1.52 and Left RAR 1.27 are both well below the threshold of 3.5-3.7 that indicates significant stenosis, confirming normal flow velocities 1, 3, 2
Record kidney measurements: Right kidney 10.37 cm and left kidney 11.77 cm are both within normal range (>10 cm), indicating no chronic ischemic atrophy 1, 4
Confirm venous patency: Both renal veins patent with no evidence of thrombosis or compression 5
Critical Technical Limitation Statement
You must explicitly document that body habitus limited the examination, as this is a recognized factor that reduces diagnostic accuracy of duplex ultrasound and may result in false-negative results even with severe stenosis 5, 1. The American College of Radiology guidelines emphasize that large body habitus can obscure visualization of the entire renal artery, particularly ostial segments 1.
Recommended Documentation Format
Document as follows:
"Bilateral renal artery duplex ultrasound demonstrates:
- No hemodynamically significant stenosis of bilateral renal arteries
- Peak systolic velocities within normal limits throughout visualized segments
- Renal-aortic ratios: Right 1.52, Left 1.27 (normal <3.5)
- Normal intrarenal vascular perfusion bilaterally without tardus-parvus waveforms
- Patent bilateral renal veins without thrombosis
- Normal kidney sizes: Right 10.37 cm, Left 11.77 cm
- Technical limitation: Study quality adequate but technically difficult due to body habitus, which may reduce sensitivity for detecting stenosis"
Clinical Interpretation Guidance
When to Consider Additional Imaging
Despite normal findings, recommend proceeding to CT angiography or MR angiography if clinical suspicion remains high for renal artery stenosis, particularly given the technical limitation 1, 6. The American Heart Association specifically warns not to assume a negative duplex ultrasound rules out renal artery stenosis in patients with high clinical suspicion, as false-negative results can occur even with severe stenosis in technically challenging patients 1.
High-Risk Clinical Scenarios Requiring Further Imaging
- Resistant hypertension despite multiple antihypertensive agents 4
- Acute kidney injury precipitated by ACE inhibitors or ARBs 6, 4
- Flash pulmonary edema with refractory hypertension 6, 4
- Progressive azotemia in elderly patients with atherosclerotic disease elsewhere 4
Velocity Thresholds for Reference
While your study shows normal velocities, document awareness that:
- Peak systolic velocity (PSV) ≥200-285 cm/s indicates ≥60% stenosis 1, 2
- RAR ≥3.5-3.7 indicates significant stenosis 1, 3, 2
- Your patient's values are well below these thresholds, supporting the normal interpretation
Common Documentation Pitfalls to Avoid
Do not document this as definitively ruling out renal artery stenosis given the body habitus limitation—instead, state findings are "consistent with" or "demonstrate no evidence of" stenosis while acknowledging the technical constraint 1.
Do not omit the technical limitation statement, as this is medicolegally important if the patient later proves to have stenosis that was not visualized due to body habitus 5, 1.
Do not fail to document the RAR values, as these provide objective hemodynamic data that support your interpretation and are more specific than PSV alone 7, 3, 2.
Include a statement about study quality (you noted "adequate"), as duplex ultrasound accuracy depends heavily on technical factors and operator expertise 5, 8.