See ultrasound ("ultrasound scanning method"), prefix trans- ("through"), vaginal ("relative to the vagina"), transvaginal.
Transvaginal ultrasound is a photograph or image achieved with an ultrasound scanner that emits low-frequency ultrasound. There are two types of gynecological ultrasounds: vaginal (transvaginal) and abdominal. Both types of scans can be done in 2D, 3D or 4D.