Placenta accreta

Case contributed by Dr Simon Meagher


Placental re-assessment at 33 weeks gestation.

Antenatal ultrasound


Transabdominal and transvaginal ultrasound demonstrate an abnormally low position of the placenta, covering the anterior lower uterine segment, and also the internal cervical os, in keeping with a major grade placenta previa.  

Multiple blood filled spaces are noted throughout the placenta (placental lacunae), a finding associated with abnormal placental adherence.

There is marked thinning of the anterior myometrium, with no appreciable myometrial tissue demonstrated between the placenta and the bladder serosa.

Color imaging further supports the diagnosis, with marked placental vascularity and increased vascularity of the uterine-bladder interface

Case Discussion

Abnormal placental adherence is an important cause of maternal peripartum morbidity and mortality due to massive hemorrhage.  

Awareness of the sonographic findings and vigilant imaging of patients with risk factors - in particular placenta previa and multiple previous Cesarian sections - increases the likelihood of accurate prenatal diagnosis. 

This in turn enables adequate pre-operative preparation, such as planned delivery at a tertiary institution, and preparation of a large quantity of crossmatched red blood cells.

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