**Core Concept**
The venous drainage of the upper part of the uterus and placenta occurs via the ovarian veins, which drain into the internal iliac veins and ultimately the inferior vena cava. This is due to the anatomical proximity of the upper uterine segments to the ovaries and the ovarian venous plexus.

**Why the Correct Answer is Right**
The upper part of the uterus, especially in the first trimester, is anatomically adjacent to the ovaries. The ovarian veins, which originate from the ovarian plexus, receive venous blood from the upper uterine segment and placenta. These veins drain into the internal iliac veins, but the direct drainage pathway from the upper uterus is via the ovarian veins. This is a key point in understanding uterine and placental vascular anatomy.

**Why Each Wrong Option is Incorrect**
Option B: Uterine veins drain the lower uterine segment and body, not the upper part. They are not responsible for upper uterine or placental drainage.
Option C: Internal iliac vein is a terminal recipient of venous blood from the uterine and ovarian veins, but it is not the direct drainage pathway.
Option D: Incorrect because venous drainage does occur — the upper uterus and placenta are not avascular.

**Clinical Pearl / High-Yield Fact**
In early pregnancy, the upper uterine segment drains via ovarian veins, making ovarian vein thrombosis a rare but serious cause of pelvic pain and miscarriage. Always remember: ovarian veins drain upper uterus, not lower.

✓ Correct Answer: A. Ovarian vein