Placenta Accreta

Dec 21, 2011
Michelle Parker

Different types of placenta accreta - By TheNewMessiah at en.wikipedia (Transferred from en.wikipedia) [Public domain], from Wikimedia Commons

Placenta accreta is a rare condition that can arise during pregnancy due to abnormal attachment of the placenta to the uterus.

Placenta accreta is a case of when all or part the placenta attaches abnormally to the myometrium, the muscular layer of the uterus. Normally, the placenta attaches to the endometrium of the uterus, which is called the decidua during pregnancy. The myometrium is the second layer, after the endometrium. Different types of placenta accreta exist, including

Placenta accreta, the placenta attaches to the myometrium
Placenta increta, the placenta invades into the myometrium
Placenta perceta, the placenta invades through the myometrium.

Bleeding in the third trimester or uterine contractions can be a common feature of placenta accreta. In normal pregnancies, the placenta detaches from the uterus lining. Placenta accreta usually results in the failure of the placenta to separate from the uterus at birth. This failure to separate from the uterus can result in massive postpartum haemorrhage and other complications. That is why cases of placenta accreta are managed to avoid these complications.

Risk factors

Factors that may predispose an individual to placenta accreta include

placenta previa
previous caesarean section
multiparity
advanced maternal age
previous uterine surgery
endometrial defects.

Diagnosis

Antenatal diagnosis of placenta accreta is usually achieved using ultrasound sonography in the second or third trimester. In cases where ultrasound is inconclusive, magnetic resonance imaging can be used to confirm the diagnosis of placenta accreta.

Management

Most cases of placenta accreta, due to the potential for massive postpartum haemorrhage, require a hysterectomy. Surgery is usually performed with the uterus incision above the placenta’s attachment site and the placenta left in place to avoid massive haemorrhage.

Because a hysterectomy is not without surgical complications and also denies future fertility, uterine conservative management may be an alternative where appropriate. Such management might involve delayed removal of the placenta, embolization of the uterine arteries, methotrexate therapy, removal of the affected uterine segment, curettage and oversewing of the implantation site of the placenta. However patients conservative management may pose unpredictable outcomes and significant consequences, including death.

References:

Cunningham, F.G., Leveno, K.J., Bloom, S.L., Hauth, J.C., Rouse, D.J., and Spong, C.Y. (2010). Williams obstretrics (23rd ed.). USA: McGraw-Hill.
Francois, K.E. and Foley, M.R. (2007). Antepartum and Postpartum Hemorrhage. In Gabbe, S.G., Niebyl, J.R. and Simpson, J.L. Obstretics: Normal and problem pregnancies (5th ed.). Philadelphia: Churchill Livingstone.
Oyelese, Y., & Smulian, J. C. (2006). Placenta previa, placenta accreta, and vasa previa. Obstetrics & Gynecology, 107(4), 927-941.
Scearce, J. and Uzelac, P.S. (2007). In DeCherney, A.H. and Nathan, L. Current diagnosis and treatment: Obstretrics and gynecology (10th ed.). USA: McGraw-Hill.