Transvaginal ultrasound is when a sonographer inserts an ultrasound transducer into a woman’s vagina for internal imaging. They can detect a variety of conditions, including but not limiting to cancers or other growths, fluid deposits, bone damage, . . . it is useful for many valid diagnostic reasons.
There are, however, some risks associated with having the transducer closer to the fetus: One study detected damage in microvilli extracted from fetuses exposed to transabdominal ultrasound, but not transvaginal for the same duration: http://www.ncbi.nlm.nih.gov/pubmed/11776185
[Influence of sonographic examination on embryo villi during early pregnancy].
To evaluate the effects of sonographic examination on embryo villi during early pregnancy.
Eighty early pregnant women intended for artificial abortion were divided into 4 groups: group I served as control, the remaining 3 groups underwent pelvic sonographic examination transabdominally for 10 minutes (group II), transvaginally for 3 minutes (group III) or for 10 minutes (group IV) respectively. After 1 hour embryo villi were obtained through artificial abortion and examined by electronic microscopy, biochemical methods and sister chromatid exchanges (SCE).
In group IV, but not group II, III, the embryo microvilli were found broken, lost and disarranged. The rough endoplasmic reticulum of trophoblasts expanded. Their malondial dehyde levels increased while the superoxide dismutase (SOD) decreased as compared with control (P < 0.01). There was no difference of SCE among these 4 groups.
It is recommended that sonographic examination should be done through abdominal approach for shorter than 10 minutes during early stage of pregnancy.