obstetrics and gynecology practices to visualize an embryo or fetus in utero, or to visualize a woman’s reproductive organs. Obstetric sonograms have traditionally been done by placing a transducer on the abdomen of the pregnant woman. More recently, however, advanced highly sensitive ultrasound probes have been developed that are placed in the woman’s vagina, resulting in transvaginal scans that provide pictures that are clearer, particularly in the early months of pregnancy and in obese women. In addition, a full bladder is not needed to obtain high-quality images, as for abdominal probes, resulting in greater comfort for the patient.
Dopplers, which are used to detect and measure fetal heart rate, also utilize both abdominal and vaginal probes. Some of these probes are waterproof, making them suitable for use during water births. The probes emit a sound wave, which is reflected back to the probe by the movement of the fetus’ heart. The difference in frequency between the emitted wave and the reflected wave that is received by the probe is known as the Doppler shift and is converted into the sound produced by the Doppler unit.
Low frequency Doppler probes penetrate deeper in the body and have a wider beam, while higher frequency Doppler probes have a narrower beam and do not penetrate as deeply. As such, a probe with a low frequency of 2 or 3 MHz is optimal for detecting relatively deep “objects” such as a fetal heartbeat, with 3 MHz probes used in early pregnancy and 2 MHz probes used later in the pregnancy.
Transvaginal ultrasound is indispensable in diagnosing gynecological diseases as well as during pregnancy. High frequency probes achieve extremely high accuracy, facilitating diagnosis of uterine pathologies, lesions, endometrial polyps and adenomyosis. The probes enable operators to gather detailed information about ultrasonographic morphology of the gonads.
In addition to ultrasound and Doppler probes, a variety of other probes are also used for gynecological procedures. Ribbed urogenital probes are used to obtain material from the cervical channel and urethra for cytological or microbiological tests. Electrically heated probes, known as electrocautery devices, are used to coagulate fallopian tube tissue as a means of sterilization. Cryogenic probes may be used to treat pre-tumorous disease of the cervix.