Assessment of the implantation site by transvaginal ultrasonography.

OBJECTIVE

To investigate the implantation site in a singleton pregnancy.

DESIGN

Transvaginal ultrasonography (US) was performed at the mid or late follicular phase and/or at very early gestation before 6 weeks.

SETTING, PATIENTS: Ultrasound monitoring was performed on 21 women with spontaneous cycles or treated by administration of 2.5 mg/d bromocriptine mesylate (Parlodel; Sando Co., Tokyo, Japan) for occulted hyperprolactinemia at the Fertility Clinic of the Department of Obstetrics and Gynecology at Gunma University Hospital.

MAIN OUTCOME MEASURES

The site of the ovary with a growing follicle and/or a corpus luteum of pregnancy, and the location of a gestational sac in longitudinal and transverse views were observed.

RESULTS

When ovulation occurred in the right ovary, 12 of the 14 gestational sacs were located on the right wall, 1 on the midwall, and 1 on the left wall. Ovulation in the left ovary resulted in 5 gestational sacs located in the left wall and 2 on the midwall. That is, of 21 gestational sacs, 17 were located on the ipsilateral uterine wall to the ovulating ovary, 3 on the midwall, and only 1 on the contralateral.

CONCLUSION

Implantation occurs on the ipsilateral uterine wall to the ovulating ovary.