Placenta praevia--comparison of four sonographic modalities

The aim of this study was the evaluation of four ultrasound modalities (transabdominal, perineal, transvaginal and transrectal) to examine placenta praevia or low lying placenta.

We prospectively investigated 24 patients after 25 weeks of their pregnancy with suspected placenta praevia or low lying placenta. We analysed picture quality and compared the results of all four scanning modalities with the actual diagnosis made at delivery.

The abdominal and perineal approach provided significantly poorer scanning quality (good or moderate in 79/38 %) as compared to the transvaginal and transrectal approach (good or moderate in 83/97 %). We can state similar results concerning accuracy of the diagnosis (abdominal/perineal 42/21 %, transvaginal/transrectal 67/86 %).

Our study supports the diagnostic superiority of transvaginal ultrasound in the diagnosis of placenta praevia in comparison to the abdominal/perineal view. We also show that transrectal scanning is at least equivalent in quality and safety without the imminent risks of transvaginal manipulation and infection.

The evaluation of the transrectal approach proved equivalent to the standard transvaginal approach in depiction quality and diagnostic safety. Thus, with less potential trauma to the pregnancy, it is a reasonable alternative.