**Question:** A multigravida at 35 weeks' gestation had the following finding on ultrasound. The following can be the causes except:

A. Fetal hydrops
B. Fetal growth restriction
C. Placenta previa
D. Polyhydramnios

**Correct Answer:** **C. Placenta previa**

**Core Concept:** Placenta previa is a complication in pregnancy where the placenta is positioned low in the uterus and partially or completely covers the internal cervical os (opening of the uterine عنق الرحم). This can lead to increased risk of bleeding during labor and delivery.

**Why the Correct Answer is Right:** Placenta previa is a specific placental location issue, which can lead to complications. In this case, the correct answer "C" is right because Placenta previa is not a cause of the ultrasound findings mentioned in the question. Other causes include:

1. **A. Fetal hydrops**: Fetal hydrops is a condition characterized by the accumulation of fluid in various body cavities, leading to generalized edema and increased risk of infections. It can be caused by various genetic and acquired disorders.

2. **B. Fetal growth restriction**: This refers to a condition where the fetus fails to achieve its expected growth potential due to insufficient blood supply or placental dysfunction. This can lead to developmental abnormalities and increased risk of complications during labor and delivery.

3. **D. Polyhydramnios**: It is excessive accumulation of amniotic fluid in the amniotic sac, leading to increased risk of preterm labor and possible infections. Polyhydramnios can be caused by various factors, including placental dysfunction and maternal diabetes.

**Why Each Wrong Option is Incorrect:**

1. **A. Fetal hydrops**: This is a specific cause of ultrasound findings mentioned in the question. The correct answer is not hydrops, as it is not a cause of ultrasound findings related to placental location.
2. **B. Fetal growth restriction**: This is a specific cause of ultrasound findings mentioned in the question. The correct answer is not growth restriction, as it is a cause of ultrasound findings related to fetal growth and not placental location.
3. **D. Polyhydramnios**: This is a specific cause of ultrasound findings mentioned in the question. The correct answer is not polyhydramnios, as it is a cause of ultrasound findings related to excessive fluid accumulation and not placental location.

**Clinical Pearl:** Understanding the various causes of ultrasound findings is essential for effective prenatal care and decision-making regarding the course of labor and delivery. By recognizing these causes, healthcare professionals can identify and manage complications effectively, ensuring better maternal and fetal outcomes.