**Question:** Which of the following is true about vasa previa except?

A. Vasa previa is a rare condition where the fetal vessels (umbilical and/or ovarian arteries) protrude through the lower segment of the cervix into the vagina during pregnancy.
B. Vasa previa usually presents with fetal bradycardia (a slow heart rate) during a routine ultrasound examination.
C. Vasa previa is a clinical diagnosis that can be made during labor when the premature rupture of membranes is accompanied by heavy bleeding.
D. The risk of vasa previa is higher in pregnancies with a history of previous cesarean sections.

**Correct Answer: D.**

**Core Concept:** Vasa previa is a rare obstetric complication characterized by the exposure of fetal vessels (umbilical and/or ovarian arteries) through the lower segment of the cervix into the vagina. This can lead to life-threatening hemorrhage during delivery.

**Why the Correct Answer is Right:** Vasa previa is a specific condition, and thus, it is unusual for the risk to be higher in pregnancies with a history of previous cesarean sections (option D). While cesarean sections can increase the risk of uterine scar rupture during labor, the risk of vasa previa remains low and unrelated to cesarean section history.

**Why Each Wrong Option is Incorrect:**

A. Vasa previa is a rare condition, but option A is incorrect as it states that vasa previa is a clinical diagnosis that can be made during labor when the premature rupture of membranes is accompanied by heavy bleeding. However, vasa previa is diagnosed antenatally (before delivery) through ultrasound examination.

B. Vasa previa is usually diagnosed antenatally through ultrasound examination and can lead to fetal heart rate decelerations (decrease in fetal heart rate) rather than bradycardia (slow heart rate).

C. While vasa previa can present with heavy vaginal bleeding during labor, the statement "accompanied by heavy bleeding" is not essential for the diagnosis. Vasa previa is diagnosed based on the ultrasound findings of fetal vessels protruding through the cervix into the vagina.

**Clinical Pearl:** Ultrasound examination is the primary diagnostic tool for vasa previa, typically detected before labor. This condition requires immediate management to prevent severe hemorrhage during delivery.