Ultrasound measurements have many applications in the infertility evaluation and are also used for monitoring during in vitro fertilization (IVF) cycles. The transvaginal ultrasound (through the vagina) is used frequently because it allows the physician to view the ovaries, uterus, and many other internal organs.
The ultrasound produces images similar to an x-ray; however, sound waves are used instead of radiation. Many times dense structures, such as uterine fibroids, are clearly visible on transvaginal ultrasound. The ultrasound is also able to show the follicles on the ovaries as they develop and are ovulated. The fertility specialist must know the number and size of the follicles during IVF cycles as this information helps in adjusting medication dosages.
Ultrasound is used to measure the width of the endometrium (lining of the uterus), which must thicken and become more vascular to accept a developing embryo. It is also used as a means to document pregnancy by visualizing the fetal heartbeat.