Two weeks after a fracture of the femur, a 33-year-old female is seen for swelling of the calf of the same leg. The preliminary diagnosis, prior to performance of any noninvasive testing, should include:

In this scenario involving a 33-year-old female who presents with calf swelling two weeks following a femur fracture, the preliminary diagnosis must consider conditions that could lead to swelling in the affected limb.

Deep vein thrombosis (DVT) is a crucial consideration in this context. The immobilization associated with a femur fracture often predisposes patients to venous stasis, which can facilitate the formation of a clot in the deep veins of the legs, leading to swelling and pain. The timing and the history of trauma make DVT a likely occurrence in this case.

Arteriovenous fistula is another potential diagnosis to consider, although less common in this immediate context. While a fistula could lead to altered circulation and swelling in the limb, it is not as directly linked to the recent fracture as DVT.

Popliteal entrapment is generally associated with vascular issues and anatomical variations, and while it can cause limb swelling and pain, it is a less likely immediate cause following a recent fracture.

Given the circumstances of recent trauma, immobilization, and resultant swelling, both DVT and arteriovenous fistula are plausible conditions to consider. Therefore, the selection of two out of these three potential diagnoses as significant considerations prior to testing is