Changes in ultrasonography indicators of abnormally invasive placenta during pregnancy.

OBJECTIVE: To ascertain whether the prevalence of ultrasonography signs of abnormally invasive placenta (AIP) changes during pregnancy.

METHODS: The present retrospective analysis included women with a prenatal diagnosis of AIP that was confirmed at delivery between January 1, 2007, and April 30, 2017, at the Department of Obstetrics and Gynaecology, Arnas Civico Hospital, Palermo, Italy. Ultrasonography signs of AIP were recorded at four different intervals during pregnancy: early first (6-9 weeks), first (11-14 weeks), second (15-24 weeks), and third trimester (25-36 weeks).

RESULTS: There were 105 pregnancies included. Low implantation of the gestational sac was present on all ultrasonography images from the early first trimester compared with on 23 of 83 (27.7%) images from 11-14 weeks of pregnancy. The identification of loss of the clear space, placental lacunae, bladder wall interruption, and uterovesical hypervascularity all increased (all P<0.001) from the early first trimester onwards; these could all be identified in a majority of patients at 11-14 weeks of pregnancy.

CONCLUSIONS: The prevalence of ultrasonography signs suggestive of AIP varied throughout pregnancy. During the early first trimester, indicators of AIP were similar to those of a cesarean scar pregnancy; classical ultrasonography signs of AIP were already present at 11-14 weeks of pregnancy for most patients.