To explore the ultrasonographic imaging characteristics of placenta increta and clinical data, and analyze the reasons for failure to make an accurate diagnosis.

By means of a retrospective analysis of 27 patients with placenta increta confirmed by operation and pathologic examination from January 2014 to May 2017 in the General Hospital of the People′s Liberation Army (also Hospital 301 for short), the reasons for missed diagnosis and misdiagnosis are comprehensively summarized.

The ultrasound examination in all the 27 cases (5 cases of first pregnancy, 17 cases of scar, 5 cases of maternal) illustrated the poorly-defined boundary between placenta and uterus mesometrium, the loss of retroplacental space, multiple lacunae echo areas, and the incomplete high-echo area of the serous membrane of placenta and bladder (involving the bladder); despite 3 normal placenta, the rest 24 were all diagnosed as placenta previa before operation, of which 20 belonged to central placenta previa and the other 4 belonged to marginal placenta previa. Twenty liveborn infants were delivered in the study, 13 of them went through abdominal hysterectomy after cesarean section surgery, 8 of them only received cesarean section surgery; 2 of them went through vaginal hysterectomy, 1 received cesarean section surgery after interventional embolization, 1 Uterine rupture in utero before got to the hospital, with the rest 2 received interventional embolization clamp scraping as a consequence of deadly induced labor or stillbirth. Postoperative placenta increta types demonstrated adhensive implantation, penetrating implantation, and implantation into muscular but not membrane layer in 3, 2, and 22 cases respectively. In terms of implanting position, only 3 patients (3/17) with cicatricial uterus did′t undergo the implantation into the scar area mainly in the left wall, left anterior wall and posterior wall, as for patients with non-scar uterus, posterior wall implantation was the main mode presented in 6 cases (6/10). Fifteen of all the involved 27 cases were identified while 12 cases failed to be distinguished. The deep reasons of misdiagnosis were placental location (placenta adheres to the posterior wall), fetal head shelter, or small placental placement, gestational age, larger range of placenta implantation, emergency ultrasound only pay attention to the emergency situation and ignore the exist at the same time, experience of inspectors with placenta increta and so on.

Although there are some limitations in prenatal ultrasound diagnosis of placenta, it is still an important method for the diagnosis and prenatal dynamic monitoring of the condition before the placenta implantation.