**Question:** In a multipara, the most common cause of Postpartum Haemorrhage is?

A. Placenta previa
B. Placenta abruptio
C. Uterine atony
D. Vasa praevia

**Core Concept:** Postpartum Hemorrhage (PPH) is defined as bleeding from the genital tract within 42 days of giving birth. In multiparas, the most common causes are related to uterine involution and uterine bleeding mechanisms.

**Why the Correct Answer is Right:** In multiparous women, the commonest cause of PPH is **Uterine atony**. Uterine atony occurs due to inadequate uterine contractility, leading to insufficient involution of the uterus after delivery. This results in reduced uterine wall thickness and inadequate uterine contractions, causing delayed or inadequate involution and increased bleeding.

**Why Each Wrong Option is Incorrect:**

A. **Placenta previa:** Placenta previa is a rare cause of PPH, particularly in multiparas. It occurs when the placenta is positioned low in the uterus and blocks the cervix, leading to excessive bleeding during or after delivery.

B. **Placenta abruptio:** Placenta abruptio is another rare cause of PPH. It occurs when the placenta detaches prematurely from the uterine wall, leading to excessive blood loss. In contrast to placenta previa, it is more common in multiparas.

C. **Vasa praevia:** Vasa praevia is a rare cause of PPH, particularly in primigravidae. It occurs when the fetal vessels are located abnormally low in the uterus and are exposed to rupture during labor or delivery, leading to excessive bleeding. In multiparas, this cause is less common due to previous uterine scarring and contractility changes associated with previous pregnancies.

D. **Vasa praevia:** Similar to vasa praevia, vas praevia is also a rare cause of PPH, particularly in primigravidae. It involves the same mechanism as vasa praevia, with low-lying fetal vessels that can rupture during labor or delivery, causing excessive bleeding. In multiparas, this cause is less common due to previous uterine scarring and contractility changes associated with previous pregnancies.

**Core Concept:** Postpartum hemorrhage, also known as PPH, is a significant cause of maternal morbidity and mortality worldwide. Early recognition and management are critical to prevent severe complications.

**Clinical Pearl:** In multiparous women, the most common cause of postpartum hemorrhage is **Uterine atony**, which is a consequence of inadequate uterine contractility and involution. This occurs due to changes in uterine contractility and involution associated with previous pregnancies. The other options are less common in multiparous women due to scarring and changes in contractility associated with previous pregnancies.