**Question:** Thromboembolism after pelvic surgery is usually from the veins -

A. Internal iliac veins
B. External iliac veins
C. Femoral veins
D. Sacral veins

**Correct Answer:** .

**Core Concept:** Pelvic surgery is a risk factor for venous thromboembolism (VTE), which includes deep vein thrombosis (DVT) and pulmonary embolism (PE). This occurs due to the combination of surgery-induced venous stasis, venous wall damage, and hypercoagulable state. In the pelvic region, most VTEs arise from the deep veins draining the lower limbs and pelvis.

**Why the Correct Answer is Right:** Thromboembolism in pelvic surgery primarily occurs due to the involvement of the pelvic veins. The deep veins of the lower limbs and pelvis are the primary sources of thromboembolism in this scenario. The correct answer represents the main culprits:

A. **Internal iliac veins:** These veins drain the pelvic organs and are located within the pelvic cavity. The risk of DVT and PE from internal iliac veins is relatively low, as they are relatively distant from the heart and have a shorter venous length.

B. **External iliac veins:** These veins also drain the pelvic organs and are connected to the deep veins of the thigh. External iliac veins are more prone to thromboembolism as they are closer to the heart and have a shorter venous length.

C. **Femoral veins:** These veins are the most superficial veins in the pelvis, draining the lower limbs. Due to their proximity to the heart and shorter venous length, thromboembolism from femoral veins is more common than internal and external iliac veins.

D. **Sacral veins:** These veins are located in the pelvic region and drain the lower limbs. Thromboembolism from sacral veins is uncommon, as they are relatively distant from the heart.

**Why Each Wrong Answer is Incorrect:**

A. **Internal iliac veins:** Although they are relatively distant from the heart, their connection to the deep veins of the thigh makes them a source of thromboembolism. However, the correct answer represents the more common sources.

B. **External iliac veins:** These veins are a significant source of thromboembolism due to their close proximity to the heart and shorter venous length. The correct answer (C) is more specific and accurate.

C. **Sacral veins:** As mentioned, thromboembolism from sacral veins is uncommon due to their distance from the heart. The correct answer (C) is more precise and relevant.

D. **Femoral veins:** Although they are close to the heart, their connection to the deep veins of the lower limbs makes them a common source of thromboembolism. The correct answer (C) is more specific and accurate.