Which of the following is the most common predisposing factor for placenta accreta? (AIPG 2008)
|C||Previous cesarean section|
a. Placenta accreta is an extremely rare condition in which the placenta is directly anchored to the myometrium partially or completely without any intervening deciduas. The probable cause is defective decidual formation.
b. This condition is usually seen when the placenta is implanted in the lower segment (placenta praevia) or over the previously injured sites such as– on caesarean section scar, dilatation and curettage operation, manual removal, synaecolysis or myomectomy.
c. The diagnosis is made only during attempted manual removal when the plane of cleavage between the placenta and the uterine wall cannot be made out. Ultrasound imaging, color Doppler and MRI have all been valuable in the diagnosis of placenta accreta during pregnancy.
d. Pathological confirmation includes:
i. Absence of decidua basalis
ii. Absence of Nitabuch’s fibrinoid layer, and
iii. Varying degree of penetration of the villi into the muscle bundles (increta) or up to the serosal layer (percreta).
e. The risks include hemorrhage, shock, infection and rarely inversion of the uterus.
f. 10% of cases of placenta previa are associated with placenta accreta, an abnormally firm attachment of the placenta to the uterine wall.
g. Placenta accreta prevents the placenta from separating from the wall of the uterus at the time of delivery and can cause severe bleeding that often necessitates a hysterectomy.
h. Placenta accreta is particularly common in women with placenta previa and one or more previous caesarean sections and may complicate 1/3 to ½ of all such cases.
i. More than 50% of the patients with Placenta Accreta require a blood transfusion–William’s obstetrics.