Study on the diagnosis of placenta membranacea using a new method of abdominal wall low frequency vibration

Objective To study the value of the new method of abdominal wall low frequency vibration (AWLFV) by prenatal ultrasound in diagnosis and differential diagnosis of placenta membranacea (PM). Methods Thirty-six cases of abnormal placenta were enrolled into the study. AWLFV was used in all 36 cases. The vibration was conducted with a frequency of 3 to 5 times per second and a duration less than 3 seconds at a time. And then the placenta was immediately observed to record the placenta echogenicity changes, and in the same place the thickness of the placenta was measured. The echo characteristics of PM and other abnormal placenta was compared. Results Thirty-six cases were finally diagnosed as complete PM in 2 cases, partial PM in 16 cases, placental sinus in 15 cases, and placental chorionic hemangioma in 3 cases. The echo characteristics of complete and partial PM were obviously different before and after AWLFV on ultrasonic image. The homogeneous echotexture of PM before AWLFV was changed immediately to the inhomogeneous echotexture after AWLFV. The ″spiral shape″ of the placenta was displayed. And in other plasental anomalies this feature was not observed before and after vibration. Conclusion The AWLFV is an effective method in diagnosis and differentiation of PM. Key words: Placenta membranacea; Diagnosis, differential; Ultrasonography, prenatal