To explore the sonographic features, diagnosis, differential diagnosis and prognosis of placental mesenchymal dysplasia (PMD). Because ofthe lack of knowledge about the ultrasonic patterns of this kind of disease, misdiagnosis frequently happens. Throughreviewing the cases and relevant researches, we are able to understand the disease and figure it out inultrasonic images.

Six cases of patients with Placental mesenchymal dysplasia were reviewed which werehospitalized in Beijing Obstetrics and Gynecology Hospital during 2013 to 2017. All of the patients underwentultrasound examinations before surgery. And the diagnosisof placental mesenchymal dysplasia was confirmed by placental pathology. Inclusion criteria for the review were diagnosis of PMD as defined by placental pathology, description of placental morphology on antenatal ultrasound and reporting of pregnancy outcomes.

All of 6 patients were found abnormal ultrasound results at routine examination of the pregnancy. The placentas were enlarged, partly with mini cysts at 12 weeks. The sonographic featurewas peak at 22 weeks, the local hive hypoechoic region of the placenta subsurface had clear border with normal placental tissue. Most of the cystic echoes of different size in the area were long circular, parallel to the distribution of the long axis of the placenta, and then the cystic change of the lesion gradually reduced, and the lesion area gradually returned to the similar state as 12 weeks of pregnancy, but it had clear border with the surrounding normal placental tissue at the 28 week of pregnancy. Some patients had umbilical vein dilation. One case PMD and fetal omphalocele suggestive of Beckwith-Wiedemann syndrome.

When a cystic placenta is detected by ultrasound examination, placental mesenchymal dysplasia should be considered in the differential diagnosis. PMD must be differentiated from gestational trophoblastic disease because management and outcomes differ.