[Diagnosis of popliteal cysts and their complications]

Popliteal cysts and their complications (rupture, expansion and pseudothrombosis) all of which may simulate deep venous thrombosis of the lower extremity may be diagnosed reliably by ultrasonography. Even small cysts can be detected, their extension can be defined and rupture with leakage of fluid into the surrounding muscles can be diagnosed. Phlebography can be avoided in most cases. Arthrography rarely gives additional information. Ultrasonography of the erect patient is recommended if rupture is suspected.