Ultrasound made using a transvaginal sensor is considered the most reliable. The device, protected by a condom and inserted into the vagina, is located very close to the woman's pelvic organs, which are to be examined. At an initial time of 3 to 6 weeks, diagnosis is carried out only if there is a suspicion that the embryo is fixed in the wrong place, and an ectopic pregnancy could occur.
More accurate data obtained using the sensor helps the doctor not to be mistaken in the timing of conception with an error of a couple of days. Sometimes it is necessary to take into account the structural features of a woman's organs in order to make a correct diagnosis. The study should be carried out on an empty bladder to avoid data distortion. It is recommended to visit the toilet immediately before entering the office and starting the procedure.