DVT: compress, don't admire

Answer c. In the groin the vein sits medial to the artery, with the femoral nerve lateral to both. The order lateral to medial is nerve, artery, vein. The vein lies alongside the artery at the groin, not above or below it. The popliteal fossa is different, where the vein lies superficial to the artery.

Answer c. The deformed artery shows you pressed hard enough. A vein which does not close fully under that pressure contains thrombus, even if you see no clot. More pressure only makes sense when the artery has not changed shape. Longitudinal compression gives false reassurance. Colour Doppler adds little to a clear compression result.

Answer d. In longitudinal, a small sideways slip takes the vein out of the beam, and the screen shows what looks like a collapsed vein. In transverse you keep the artery and vein on screen together and watch the walls meet. Fresh clot is often black on screen, so its appearance does not decide the plane.

Answer b. Behind the knee the order flips compared with the groin. The popliteal vein sits between the skin and the popliteal artery, so you meet it first and compress it against the artery. The anterior tibial artery leaves below the knee, at the front of the leg. The deep femoral vein runs in the thigh.

Answer c. A negative proximal scan does not exclude a calf clot which then extends upwards. NICE (NG158) advises stopping interim anticoagulation and repeating the proximal ultrasound 6 to 8 days later when the D-dimer is positive. Discharge without review misses this group. CT venography is not the routine next step. Full treatment without a diagnosis exposes the patient to bleeding risk.