A venogram (catheter venography) is the definitive test for pelvic vein problems: through a small puncture in the neck or groin, a thin catheter is guided into the pelvic veins and contrast dye is injected while X-ray images run — showing, in real time, exactly which veins fill backwards, where blood pools, and how the whole drainage system behaves.
It outranks scans for one key reason: it shows function, not just anatomy — flow direction, filling patterns, and (with pressure measurements) how much a narrowing actually matters. It's usually paired with IVUS when compression syndromes are in question.
Practically: it's a day procedure under local anaesthetic and sedation, and it's often both diagnosis and treatment planning in one visit — if a clear target is found, embolisation can sometimes happen in the same session. Where it sits in the testing order — after ultrasound and MR/CT venography — is covered in how PeVD is diagnosed.