Imaging recommendation · Abdomen · Pelvis

Renal transplant — post-operative imaging and complications

Q: What's the alternative imaging for renal transplant — post-operative imaging and complications when ra stenosis suspected on us (elevated psv, tardus parvus distal)?

MRI — MR angiography or CT angiography (iv contrast).

Q: What's the alternative imaging for renal transplant — post-operative imaging and complications when urinoma / leak suspected?

NM — MAG3 renogram or CT urogram (iv contrast).

Q: What's the alternative imaging for renal transplant — post-operative imaging and complications when suspected abscess / collection drainage?

CT — CT or US-guided drainage (iv contrast).

Q: What's the alternative imaging for renal transplant — post-operative imaging and complications when rejection vs atn — biopsy is the answer?

US — US-guided transplant biopsy (no contrast).

Q: What's the alternative imaging for renal transplant — post-operative imaging and complications when ptld suspected?

NM — FDG-PET-CT (see ptld) (iv contrast).

Recommended: Doppler ultrasound of the transplant kidney is the preferred imaging study for renal transplant — post-operative imaging and complications. Ultrasound is first-line for any concern in the renal transplant: vascular (renal artery stenosis, RA/RV thrombosis, AV fistula), peri-transplant collection (hematoma, urinoma, lymphocele, abscess), parenchymal (elevated RI suggests rejection / ATN).

Recommended study

Doppler ultrasound of the transplant kidney

US No contrast Preferred Abdomen · Pelvis Acute inpatientOutpatient Reviewed 2026-05

Ultrasound is first-line for any concern in the renal transplant: vascular (renal artery stenosis, RA/RV thrombosis, AV fistula), peri-transplant collection (hematoma, urinoma, lymphocele, abscess), parenchymal (elevated RI suggests rejection / ATN). MRI / CT for problems US can't resolve.

If the default doesn't apply

RA stenosis suspected on US (elevated PSV, tardus parvus distal)

MRI MR angiography or CT angiography IV contrast

Urinoma / leak suspected

NM MAG3 renogram or CT urogram IV contrast

Suspected abscess / collection drainage

CT CT or US-guided drainage IV contrast

Rejection vs ATN — biopsy is the answer

US US-guided transplant biopsy No contrast

PTLD suspected

NM FDG-PET-CT (see ptld) IV contrast

Watch-outs

Elevated resistive index (RI > 0.8)

Non-specific — can be rejection, ATN, obstruction, or compression by hematoma. Doesn't differentiate the cause.

Lymphocele vs urinoma vs hematoma

Timing helps: hematoma immediate post-op, urinoma days 1–7, lymphocele weeks–months.

PTLD — solid organ transplant + new mass

Can occur anywhere — bowel wall, transplant kidney itself, lymph nodes. FDG-avid.

Pearls

Normal transplant RA waveform: low-resistance, brisk upstroke, RI 0.5–0.7.
Tardus parvus + elevated PSV (> 200 cm/s) at the anastomosis → RA stenosis.
Acceleration time > 0.07 s downstream of stenosis is a strong indirect sign.
Routine post-op US: day 1, then PRN — not surveillance after the first week unless concern arises.