**Question:** All the following can be a cause for obstruction of after coming head of breech Except:

A. Placenta previa
B. Uterine rupture
C. Placenta abnormally low
D. Vacuum extraction

**Core Concept:** Obstruction of the after coming (obstetric emergency) is a situation where the head of a fetus, after passing the pelvic brim, gets stuck in the pelvis, preventing further descent. This can be caused by various obstetric factors.

**Why the Correct Answer is Right:** The correct answer is D. Vacuum extraction, a method of assisted delivery involving the use of a vacuum device to facilitate delivery, is a technique used to aid in the delivery when other methods fail or are deemed unsafe. It is not a cause for obstruction of the after coming, as its primary purpose is to facilitate delivery, not cause obstructions.

**Why Each Wrong Option is Incorrect:**

A. Placenta previa: Placenta previa is a condition where the placenta is located low in the uterus, covering part of the cervix. It can cause bleeding and rarely, maternal hypovolemic shock. Placenta previa is not a cause for obstruction of the after coming, as it is not related to the fetus's position during delivery.

B. Uterine rupture: Uterine rupture is a rare and severe complication of pregnancy where the uterus ruptures due to trauma or previous surgical intervention. Uterine rupture is not a cause for obstruction of the after coming, as it is an obstetric emergency unrelated to the fetus's position during delivery.

C. Placenta abnormally low: Placenta abnormally low refers to placenta that is located low in the uterus, but not covering the cervix. This can lead to bleeding, but not directly cause obstruction of the after coming.

**Clinical Pearl:**

Vacuum extraction is a safe and effective method for delivering a fetus when other methods fail or are deemed unsafe. It is essential to know the correct indications and contraindications for vacuum extraction, as misapplication can lead to complications or worsening of the situation. Understanding the different causes of obstruction of the after coming is crucial to make an informed decision on the appropriate management strategy, including the use of vacuum extraction when necessary.