ASSESSMENT OF THE IMPLANTATION SITE BY TRANSVAGINAL ULTRASONOGRAPHY

Objective: To investigate the implantation site in a singleton pregnan cy. Design: Transvaginal ultrasonography (US) was performed at the mid or late follicular phase and/or at very early gestation before 6 week s. Setting, Patients: Ultrasound monitoring was performed on 21 women with spontaneous cycles or treated by administration of 2.5 mg/d bromo criptine mesylate (Parlodel; Sando Co., Tokyo, Japan) for occulted hyp erprolactinemia at the Fertility Clinic of the Department of Obstetric s and Gynecology at Gunma University Hospital. Main Outcome Measures: The site of the ovary with a growing follicle and/or a corpus luteum o f pregnancy, and the location of a gestational sac in longitudinal and transverse views were observed. Results: When ovulation occurred in t he right ovary, 12 of the 14 gestational sacs were located on the righ t wall, 1 on the midwall, and 1 on the left wall. Ovulation in the lef t 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 th e ipsilateral uterine wall to the ovulating ovary, 3 on the midwall, a nd only 1 on the contralateral. Conclusion: Implantation occurs on the ipsilateral uterine wall to the ovulating ovary.