Hepatic Doppler / liver transplant — Reference values

Hepatic Doppler / liver transplant — Reference values: Transplant hepatic artery — resistive index, Hepatic artery — systolic acceleration time.

Applies to native liver, postoperative studies and liver transplant. Arterial, portal and venous criteria are used internationally, but final weight depends on postoperative timing, surgical technique, serial comparison and institutional protocol. In Brazil, keep anatomic description clear and communicate critical findings; in the US/Europe, align with ACR-AIUM, RSNA/Radiographics and local transplant protocols.

Measurements and reference values

Measurement	Usual value	Note
Transplant hepatic artery — resistive index	0,55–0,80	High values may be transient in the first 48-72 h; low index with tardus-parvus favors stenosis.usual: 0,55–0,80borderline or transient: 0,50–0,55 ou >0,80 nas primeiras 72 h sem outro alertahigh risk: <0,50 com tardus-parvus, ausência de fluxo ou piora clínicaSource: Radiographics/RSNA liver transplant Doppler / Clinical Imaging review / institutional transplant protocols
Hepatic artery — systolic acceleration time	< 80 ms	Above 80 ms is used with low resistive index and tardus-parvus waveform to suspect stenosis.brisk upstroke: <80 mstechnical zone: 80–100 ms sem baixo índice de resistênciastenosis concern: >80 ms + índice baixo/tardus-parvusSource: Radiographics/RSNA / AJR liver transplant Doppler
Hepatic artery — focal peak systolic velocity	< 200 cm/s	Velocity >=200 cm/s at the jet/anastomosis, especially with aliasing and distal waveform change, favors stenosis.no focal elevation: <150 cm/scaution: 150–199 cm/sstrong concern: ≥200 cm/s com gradiente/turbulênciaSource: Radiographics/RSNA / liver transplant Doppler reviews
Hepatic artery — absent flow	critical abnormality if confirmed	Confirm with low/high gain, slow scale, power Doppler and intra/extrahepatic search.communicate: arterial thrombosis until proven otherwise in transplantSource: Radiographics/RSNA / Clinical Imaging review
Portal vein — flow direction	toward the liver	Flow away from the liver or no flow is abnormal in the graft unless there is an intended shunt.expected: toward the liverborderline: very slow or to-and-froabnormal: away from liver, thrombus or no flowSource: StatPearls Liver Doppler / transplant Doppler protocols
Transplanted portal vein — anastomotic velocity	< 125 cm/s	Some protocols accept high velocities early postoperatively; ratio and turbulence increase specificity.usual: <100 cm/s sem turbulênciaobserve: 100–124 cm/s ou edema precocestenosis concern: ≥125 cm/s com aliasing ou razão elevadaSource: Radiographics/RSNA / liver transplant Doppler reviews
Portal vein — anastomosis/reference ratio	< 3:1	Ratio >=3:1 is a strong criterion when there is focal narrowing, turbulence or serial change.no gradient: <2:1borderline: 2–2,9:1significant: ≥3:1Source: Radiographics/RSNA / transplant Doppler protocols
Hepatic veins and inferior vena cava — waveform	phasic/triphasic	Isolated monophasic waveform can be nonspecific; absent flow, focal jet and elevated ratio suggest outflow obstruction.reassuring: phasic or triphasiccontextual: monophasic without jet/congestionlikely obstruction: no flow, thrombus, focal jet or ratio >=3:1Source: Radiographics/RSNA / UW Liver Transplant Doppler protocol
Transjugular intrahepatic portosystemic shunt — velocity	90–190 cm/s	Included for differentiation; do not confuse a shunt with the transplant portal anastomosis.usual: 90–190 cm/scaution zone: 50–90 ou 190–250 cm/slikely dysfunction: <50, >250, oclusão ou gradiente focalSource: StatPearls Liver Doppler / TIPS institutional protocols

Classifications and calculators

Interactive assistant — hepatic and transplant Doppler

Output	Color	Interpretation
Preserved pattern	Green	Patent hepatic artery, usual resistive index, brisk upstroke, portal flow toward the liver and phasic hepatic veins.
Borderline/contextual zone	Yellow	High index early postoperatively, intermediate velocity, isolated monophasic waveform or technical limitation.
Vascular alert	Red	Absent arterial flow, tardus-parvus with low index, arterial velocity >=200 cm/s, portal thrombus, portal/venous ratio >=3:1 or venous obstruction.

The assistant calculates ratios and color-codes results. In transplant, comparison with baseline Doppler can be more important than an isolated number.

Source: Radiographics/RSNA / Clinical Imaging / AJR / UW and UT Southwestern transplant Doppler protocols

Minimum technical protocol — native liver and transplant

Vessel/step	Record	Why it matters
Main hepatic artery and intrahepatic branches	Patency, resistive index, systolic velocity, systolic upstroke and sample location.	Main screening for post-transplant arterial thrombosis or stenosis.
Main portal vein, anastomosis and branches	Direction, jet velocity and reference velocity before/after.	Differentiates transient hyperflow from anastomotic stenosis.
Hepatic veins and inferior vena cava	Phasicity, focal jet, anastomotic velocity, ratio and residual flow.	Assesses outflow obstruction and graft congestion.
Surgical context	Transplant date, graft type, caval technique, stent, angioplasty and baseline exam.	Changes thresholds and avoids false positives early postoperatively.
Doppler technique	Angle up to 60 degrees, low scale for slow flow, adjusted gain, power Doppler when needed.	Avoids simulating thrombosis from slow flow or poor window.

Source: ACR-AIUM-SPR-SRU abdomen parameter / UW Liver TX Doppler / UTSW transplant protocol

Post-transplant hepatic artery — color reading

Color	Criterion	Practical reading
Green	Flow present, index 0.55-0.80, acceleration time <80 ms, no focal jet.	Compatible with arterial patency when the tracing is reliable.
Yellow	Index >0.80 in the first 72 h, velocity 150-199 cm/s or technically limited tracing.	Repeat/follow, compare with baseline and correlate with labs.
Red	No flow, index <0.50 with tardus-parvus, time >80 ms with low index, focal velocity >=200 cm/s.	Priority communication; consider complementary imaging or intervention according to protocol.

Isolated high index early postoperatively is a known pitfall; the same late finding or with graft dysfunction carries more weight.

Source: Radiographics/RSNA liver transplant Doppler / Clinical Imaging 2014

Transplanted portal vein — stenosis, thrombosis and hyperflow

Color	Finding	Interpretation
Green	Flow toward the liver, no thrombus, velocity <100 cm/s and ratio <2:1.	Usual pattern when there is no focal aliasing.
Yellow	Velocity 100-124 cm/s, ratio 2-2.9:1 or high early postoperative velocity without narrowing.	Zone dependent on edema, caliber and comparison.
Red	Velocity >=125 cm/s with aliasing, ratio >=3:1, thrombus or absent flow.	Suggests portal stenosis, thrombosis or critical flow.

Source: Radiographics/RSNA / Doppler ultrasound in liver transplant complications

Graft venous outflow — hepatic veins and inferior vena cava

Color	Finding	Reading
Green	Phasic/triphasic hepatic veins and patent cava.	Against important outflow obstruction when the rest agrees.
Yellow	Isolated monophasic waveform, mild damping or poor respiratory/technical exam.	Nonspecific; repeat and correlate with ascites, pleural effusion and congestion.
Red	No flow, thrombus, focal jet, important aliasing or ratio >=3:1.	Suggests venous outflow stenosis/occlusion.

Source: UW Liver TX Doppler / RSNA transplant imaging reviews

Native liver — hepatic Doppler outside transplant

Structure	Consensus normal	Alert
Portal vein	Flow toward the liver, diameter 6-13 mm, mean velocity 16-40 cm/s.	Flow away from liver, thrombus, cavernoma, collaterals or very slow flow.
Hepatic artery	Resistive index 0.50-0.70 outside transplant, with present diastole.	Absent flow, extreme index or tardus-parvus in the right context.
Hepatic veins	Phasic/triphasic tracing.	No flow, thrombus, compression or obstructive pattern.

In the native liver, isolated numbers rarely make the diagnosis; flow direction, thrombus, collaterals and clinical context dominate.

Source: StatPearls Liver Doppler / Radiographics liver Doppler

Pitfalls and when to escalate

Situation	Error risk	How to reduce
First 72 hours	High arterial index may reflect edema, spasm or transient increased resistance.	Compare serially and weigh graft function.
Slow flow	High scale or high wall filter may simulate thrombosis.	Lower scale, adjust gain and use power Doppler.
No arterial flow in transplant	May represent arterial thrombosis, a time-sensitive event.	Confirm technically and communicate immediately according to local workflow.
Late arterial stenosis	May cause biliary ischemia, abscesses or progressive dysfunction.	Integrate Doppler with bile ducts, collections and labs.

Source: Radiographics/RSNA / Clinical Imaging review / transplant protocols

Report checklist — hepatic/transplant Doppler

Block	Text that should not be missing	Color if absent
Identification	Time after transplant, graft/anastomosis type if known, prior comparison.	Yellow
Hepatic artery	Patency, resistive index, velocity, acceleration time and presence/absence of tardus-parvus.	Red if transplant
Portal vein	Direction, anastomotic velocity, ratio if suspicious, thrombus and branches.	Red if vascular concern
Venous outflow	Hepatic veins, cava, phasicity, focal jet and ratio when stenosis is suspected.	Yellow/red according to finding
Associated findings	Bile ducts, collections, ascites, pleural effusion and technical limitation.	Yellow

Source: CBR reporting principles / ACR-AIUM practice parameter / transplant Doppler literature

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