Discussion of Placenta accreta
- Placenta accreta, placenta increta, or placenta percreta describe abnormal placental implantation.
- Placenta accreta: placental villi extend beyond the confines of the endometrium and attach to the superficial aspect of the myometrium.
- Placenta increta: Placental villi invade the myometrium.
- Placenta percreta: Placental villi advance into the serosa or parametria.
- Placenta accreta occurs in approximately 1 in 7,000 pregnancies.
- Placenta accreta is the most common form of placental invasion (76% of cases).
- The primary risk factors for placenta accreta:
- Placenta previa
- Advanced maternal age
- Prior cesarean section.
- Accurate prenatal diagnosis of placenta accreta is vital because this abnormality is an important cause of significant hemorrhage in the immediate postdelivery period with resultant maternal and fetal morbidity and mortality. However, the diagnosis is not usually made prospectively.
- Definitive treatment for placenta accreta consists of hysterectomy with possible resection of adjacent organs if percreta is present.
- In certain instances, however, conservative treatment may be used, especially if uterine preservation is desired.
- Conservative measures include curettage, oversewing of the placental bed, and ligation of the uterine arteries or the anterior divisions of the internal iliac arteries.
 Imaging Findings for Placenta accreta
- US criteria for the diagnosis of placenta accreta have been reported: loss of the retroplacental hypoechoic zone, interruption of the hyperechoic border between the uterine serosa and bladder, presence of mass-like tissue with echogenicity similar to that of the placenta, and the visualization of prominent vessels or lakes within the placenta or myometrium.
- Magnetic resonance imaging has also been used to diagnose placenta accreta. On T2-weighted MR images, the mass is hyperintense and may be heterogeneous. In addition, T2-weighted MR images are useful in the assessment of focal thinning of the myometrium and interruption of the junctional zone.
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 References for Placenta accreta
- Ramesh Avva, Hemendra R. Shah, and Teresita L. Angtuaco. US Case of the Day. RadioGraphics 1999 19: 1089-1092.