Will Endometrial Volume Measurements Add Something New to the Diagnosis of Early Pregnancy?

Transvaginal ultrasound will detect an intrauterine pregnancy, first seen as a visible gestational sac, as early as four weeks and 3-4 days (day 31-32 of the cycle) after the last menstrual period. However, our knowledge of ultrasonically detectable endometrial changes before the gestational sac visualization is minimal. With the recent introduction of a three-dimensional (3D) ultrasound with the Virtual Organ Computer-aided Analysis (VOCAL) software, it has become possible to measure endometrial volume, which, because of the shape of the endometrial cavity, was not feasible before. Theoretically, endometrial volume in conception cycles may vary according to patients' parity, and status of pregnancy, whether it is normal or abnormal; but it should be increased in pregnant compared to non-pregnant patients. Several studies have been published, investigating the endometrial thickness and volume in the luteal phase of the conception cycle, and finding that the above-mentioned is true. Endometrium does seem to be thicker in conception compared to non-conception cycles, and in normal pregnancy compared to abnormal pregnancy. However, at present there is no enough data to confirm that endometrial volume measurement will be powerful tool in differential diagnosis of early normal and abnormal pregnancy.