**Question:** Which of the following statements concerning placenta previa is true?

A. Placenta previa is a condition where the placenta is located low in the uterus, covering the internal cervical os.
B. Placenta previa is always associated with heavy bleeding in the third trimester.
C. Placenta previa is a rare complication affecting only 1 in 1000 pregnancies.
D. Placenta previa is a condition where the placenta is located high in the uterus, covering part of the cervix.

**Correct Answer: C.** Placenta previa is a rare complication affecting only 1 in 1000 pregnancies.

**Core Concept:** Placenta previa is a condition in which the placenta is located low in the uterus, covering the internal cervical os, which is the opening of the uterine cervix into the vagina. It is associated with an increased risk of bleeding during pregnancy and labor.

**Why the Correct Answer is Right:** Placenta previa is a specific placental implantation pattern, in which the placenta is located at or below the internal cervical os. This placement increases the risk of bleeding due to mechanical trauma during labor and delivery. In this case, option C is correct as placenta previa is indeed a rare complication affecting only 1 in 1000 pregnancies.

**Why Each Wrong Option is Incorrect:**

A. Placenta previa is not specifically classified as low placental implantation, but rather the placenta covering the internal cervical os. This option is incorrect because it does not address the specific risk associated with the low placental implantation site.

B. While heavy bleeding in the third trimester is a potential symptom of placenta previa, not all cases result in heavy bleeding. This option is incorrect as it oversimplifies the clinical presentation of the condition.

D. Placenta previa is characterized by the placenta covering part of the cervix, not being high in the uterus. This option is incorrect because it contradicts the definition of placenta previa as a low placental implantation.

**Clinical Pearl:** Placenta previa is a serious obstetric condition that requires careful management during labor and delivery to prevent maternal hemorrhage. It is essential for healthcare providers to be aware of the potential complications and manage patients accordingly to ensure a safe delivery and effective postpartum care.