M/c cause of APH is
**Core Concept**
The most common cause of Antepartum Hemorrhage (APH) is related to the disruption of the normal physiological processes maintaining uteroplacental function. This involves the integrity of the placental site, particularly the decidua basalis, and the associated blood supply.
**Why the Correct Answer is Right**
The correct answer is **Placenta Previa**. This condition occurs when the placenta partially or completely covers the internal cervical os. The placental implantation site is abnormal, leading to separation of the placenta from the uterus, resulting in bleeding. The main risk factor for placenta previa is a previous uterine surgery. The bleeding in placenta previa is thought to result from the erosion of the placental implantation site into the lower uterine segment, which contains no significant blood supply to the placenta.
**Why Each Wrong Option is Incorrect**
**Option A:** **Cervical cancer** is not a common cause of APH. While cervical cancer can cause bleeding, it is not typically associated with the sudden, painless vaginal bleeding characteristic of APH.
**Option B:** **Amniotic fluid embolism** is a rare but serious condition that can cause sudden, severe bleeding. However, it is not a common cause of APH and typically occurs during labor.
**Option C:** **Uterine anomalies** can increase the risk of APH, but they are not the most common cause.
**Clinical Pearl / High-Yield Fact**
The classic teaching is that APH is characterized by painless vaginal bleeding, often accompanied by a sudden drop in maternal vital signs and fetal distress. Prompt recognition and management are critical to prevent fetal and maternal morbidity.
**Correct Answer:** C. Uterine anomalies