What is the rate of uterine blood flow at term in a primigravida?
**Core Concept**
At term, the uterus undergoes significant changes to accommodate the growing fetus, leading to increased metabolic demands and blood flow. Uterine blood flow plays a crucial role in fetal development and well-being. In a primigravida, the uterus is not accustomed to the increased demands of pregnancy, and blood flow is accordingly adjusted to meet these needs.
**Why the Correct Answer is Right**
At term, uterine blood flow in a primigravida is approximately 300-400 mL/min. This increase in blood flow is necessary to meet the high metabolic demands of the growing fetus, placenta, and uterine tissues. The myometrium and decidua receive a significant proportion of this blood flow, which is essential for maintaining uterine tone and supporting fetal growth. The increased blood flow is also necessary to facilitate the exchange of oxygen, nutrients, and waste products between the mother and the fetus.
**Why Each Wrong Option is Incorrect**
* **Option A:** 100-200 mL/min is too low to meet the metabolic demands of the fetus and placenta at term.
* **Option B:** 500-600 mL/min is higher than the typical range for uterine blood flow at term.
* **Option C:** 200-300 mL/min is closer to the range for early pregnancy, but still too low for the increased demands at term.
**Clinical Pearl / High-Yield Fact**
Uterine blood flow increases significantly throughout pregnancy, from approximately 50-100 mL/min in the non-pregnant state to 300-400 mL/min at term. This increase is essential for supporting fetal growth and development.
**Correct Answer:** A. 300-400 mL/min.