Objective  To compare the prenatal ultrasonographic features and prognostic factors of placenta accreta between first-trimester pregnancy and second-, third-trimester pregnancy.

  Methods  The clinical materials of 120 patients with placenta accreta were analyzed retrospectively, including 18 cases in first-trimester pregnancy and 102 cases in second-, third-trimester pregnancy. All the pregnant women were conducted with prenatal ultrasound examination, the efficacy of prenatal ultrasound in diagnosing placenta accreta during different periods of pregnancy was compared, and the ultrasonic characteristics were analyzed. The prognosis of pregnant women was followed up and the related factors of prognosis in pregnant women with placenta accreta were analyzed.

  Results  Compared with pregnant women with placenta accreta in second- and third-trimester pregnancy, the ultrasonic detection rate of placental accreta in the first-trimester pregnancy was lower. The ultrasonic features of placental accreta in the first-trimester pregnancy were mainly the low position of gestational sac, followed by the thinning of anterior wall muscle layer, the low echo area or sound transmission area (lacunae like) in the placenta, and the irregular decidua uterus or placenta uterus interface. The ultrasonic features of placental accreta in the second- and third-trimester pregnancy were mainly the formation of intraplacental vortex, followed by unclear boundary between placenta and uterine myometrium and cervical tissue, rich peripheral blood flow signals, disappearance of retroplacental space and abnormal thickening of placenta. Multivariate analysis showed that the history of cesarean section, postpartum hemorrhage and placenta previa were the risk factors for poor prognosis of pregnant women with placenta accreta, while the anterior wall placenta and the experience of the diagnostician were the protective factors.

  Conclusion  There are great differences in prenatal ultrasonic characteristics of placental accreta between the first-trimester pregnancy and second-, third-trimester pregnancy. The history of cesarean section, placental attachment, postpartum hemorrhage, placenta previa and the experience of the diagnostician are the main factors affecting the prognosis of pregnant women with placental accreta.