Interactive calculator — renal transplant Doppler
Source: ACR-AIUM-SPR-SRU 2024 / Clinical Radiology 2003 / AJR 2017 / UT Southwestern 2020
Renal transplant (Doppler) — Reference values
Renal transplant (Doppler) — Reference values: Minimum technical protocol, Peak systolic velocity in the graft artery, Graft artery / iliac artery ratio.
International protocols converge on the complete technical examination, but there is no single universal threshold for transplant renal artery stenosis. Interpretation should combine post-transplant timing, focal velocity, graft artery/iliac artery ratio, aliasing, intrarenal tardus-parvus waveform, resistive index, renal function and comparison with prior studies.
Measurements and reference values
| Measurement | Usual value | Note |
|---|---|---|
| Minimum technical protocol | Grayscale + color Doppler + spectral Doppler | Document graft size, parenchyma, collecting system, bladder/ureter when applicable, perigraft space, graft artery and vein, anastomoses, adjacent iliac artery/vein, and intrarenal waveforms in upper, mid and lower poles.Source: ACR-AIUM-SPR-SRU 2024 / UT Southwestern 2020 |
| Peak systolic velocity in the graft artery | <200 / 200-249 / 250-299 / >=300 cm/s | An isolated value can be false positive, especially immediately after surgery or in a tortuous artery. Risk increases with focal acceleration plus aliasing, iliac ratio >=2.0 and intrarenal tardus-parvus waveform.usually normal: <200 cm/sborderline or context-dependent: 200-249 cm/ssuspicious if isolated: 250-299 cm/sstrong when combined with direct/indirect criteria: >=300 cm/s ou >=250 cm/s + aliasing/razão alta/tardus-parvusSource: ACR-AIUM-SPR-SRU 2024 / Clinical Radiology 2003 / AJR 2017 |
| Graft artery / iliac artery ratio | <1,8 / 1,8-1,99 / >=2,0 | Helps reduce false positives from high output or elevated systemic velocities. Measure the iliac artery adjacent to the anastomosis and use the same technique on follow-up.no proportional criterion: <1,8gray zone: 1,8-1,99abnormal when focal acceleration is present: >=2,0Source: ACR-AIUM-SPR-SRU 2024 / UT Southwestern 2020 / BMUS teaching material |
| Intrarenal tardus-parvus waveform | Acceleration time >70 ms or acceleration index <300 cm/s² | This is an indirect criterion; it carries more weight when distal to a focal acceleration. It can also occur with proximal iliac stenosis, hypotension or suboptimal technique.preserved waveform: rapid systolic upstrokeisolated or technical: time >70 ms or index <300 without focal jetstrong indirect criterion: tardus-parvus + high velocity/ratioSource: UT Southwestern 2020 / BMUS teaching material |
| Intrarenal resistive index | 0,60-0,70 / 0,70-0,80 / >0,80 | It does not by itself separate rejection, tubular injury, drug toxicity, obstruction, venous compression or systemic congestion. Trend and clinical context matter more than one isolated measurement.common in stable graft: 0,60-0,70borderline or nonspecific: 0,70-0,80elevated, correlate: >0,80concerning if persistent or with dysfunction: >=0,90, fluxo diastólico ausente/reversoSource: UT Southwestern 2020 / Radiopaedia / review literature |
| Graft renal vein | Venous flow present, no thrombus and no marked focal acceleration | Absent venous flow, thrombus, marked graft enlargement and reversed arterial diastolic flow are critical findings and should be communicated.normal: patent veinevaluate compression or technique: focal acceleration without thrombuscritical: no flow, thrombus or reversed arterial diastolic flowSource: ACR-AIUM-SPR-SRU 2024 / transplant vascular complication reviews |
| Collecting system and perigraft collections | Describe grade, size, location and compressive effect | Mild dilatation may be transient; moderate/severe dilatation, complex collection or compressive collection changes management, especially with pain, fever, reduced urine output or rising creatinine.no relevant finding: no dilatation and no compressive collectionfollow/correlate: mild dilatation or small simple collectionrelevant abnormality: marked dilatation, complex or compressive collectionSource: ACR-AIUM-SPR-SRU 2024 / renal transplant ultrasound reviews |
Classifications and calculators
Acquisition checklist
| Step | What to record |
|---|---|
| Grayscale | Graft location, length, cortical thickness/echogenicity, corticomedullary differentiation, renal sinus, collecting system, ureter/stent when visible, bladder and residual urine if indicated. |
| Perigraft space | Look for hematoma, seroma, lymphocele, urinoma or abscess; measure, locate and describe complexity and compressive effect. |
| Arterial Doppler | Measure adjacent iliac artery, anastomosis, proximal, mid and hilar graft artery; look for multiple arteries, kinking, aliasing and turbulence. |
| Intrarenal Doppler | Record waveforms in upper, mid and lower poles, with resistive index, acceleration time and acceleration index when stenosis is the clinical question. |
| Venous Doppler | Confirm patent renal and iliac veins without thrombus; in hematuria or recent biopsy, look for arteriovenous fistula and pseudoaneurysm. |
Source: ACR-AIUM-SPR-SRU 2024 / UT Southwestern 2020
Graft artery stenosis — color reading
| Color | Practical criteria | How to report |
|---|---|---|
| Green | No relevant focal acceleration; velocity <200 cm/s; iliac ratio <1.8; no distal tardus-parvus. | No ultrasound criteria for hemodynamically significant stenosis on the current study. |
| Yellow | Velocity 200-249 cm/s, or isolated 250-299 cm/s in postoperative/surveillance context, or borderline ratio, especially with tortuosity or difficult angle. | Borderline/contextual finding; correlate with renal function, blood pressure and prior Doppler. |
| Red | Velocity >=300 cm/s, or >=250 cm/s associated with aliasing/turbulence, ratio >=2.0 and intrarenal tardus-parvus waveform. | Combination of findings suspicious for hemodynamically significant stenosis; communicate and consider confirmation according to local protocol. |
Source: Clinical Radiology 2003 / AJR 2017 / UT Southwestern 2020
Resistive index — cautious interpretation
| Range | Color | Comment |
|---|---|---|
| 0,60-0,70 | Green | Common range in stable grafts, but always compare with baseline and clinical context. |
| 0,70-0,80 | Yellow | Intermediate zone; may be normal in some patients and abnormal in others. |
| >0,80 | Yellow | Elevated and nonspecific: rejection, tubular injury, toxicity, obstruction, venous compression, systemic congestion and cardiovascular factors may overlap. |
| >=0,90 ou diástole ausente/reversa | Red | Concerning when persistent or associated with dysfunction; reversed diastolic flow requires prompt communication. |
Source: UT Southwestern 2020 / Radiopaedia / review literature
Complications requiring communication
| Finding | Why it matters | Color |
|---|---|---|
| No arterial flow in the graft | May represent arterial thrombosis, technical complication or severe hypoperfusion. | Red |
| No venous flow or thrombus in renal vein | May cause acute graft congestion and rapid functional loss. | Red |
| Reversed arterial diastolic flow | May occur with venous thrombosis, severe rejection, edema/high pressure or significant compression. | Red |
| Complex, infected or compressive collection | May indicate hematoma, abscess, urinoma or lymphocele affecting ureter/vessels. | Red |
| Post-biopsy arteriovenous fistula or pseudoaneurysm | May cause hematuria, vascular steal, enlargement or need for embolization. | Yellow/Red |
Source: ACR-AIUM-SPR-SRU 2024 / UT Southwestern 2020 / vascular complication reviews
Didactic impression template
Source: SonoAI synthesis from cited sources