Antonio FD et al. – The systematic review investigated if ultrasound (US) signs indicating abnormally invasive placenta (AIP) are observed in the first trimester of pregnancy and confirmed the strength of association and predictive accuracy of these signs in detecting AIP during this period. The results demonstrated the presence of US signs of AIP during the first trimester of pregnancy, especially before 11 weeks of gestation. Although, the individual predictive accuracy was not high, low anterior implantation of the placenta or sac close to or within the scar was shown to be the most common early US signs, suggestive of AIP.

Methods

• Seven studies (551 pregnancies at risk of AIP) that reported the first trimester diagnosis of AIP, which was subsequently confirmed in the third trimester either during operative delivery or pathology, were included.

Results

• A total of 91.4% cases with confirmed AIP showed at least 1 ultrasound sign suggestive of AIP.
• The most common US feature in the first trimester was low implantation of gestational sac close to the previous uterine scar, which was observed in 82.4% cases.
• In addition, 46.0% cases showed anechoic spaces within the placental mass and 66.8% cases showed a reduced myometrial thickness in cases affected by AIP.
• Risk of AIP was significantly higher in pregnancies with low implantation of the gestational sac (44.4% sensitivity and 93.4% specificity).