Three-dimensional transvaginal sonography of interstitial pregnancy.

We describe the case of a 33-year-old pregnant woman, gravida 1 para 0, who was referred to us with a presumptive diagnosis of an interstitial pregnancy. The patient had had amenorrhea for 7 weeks and had previously undergone myomectomy. Two-dimensional sonographic examination revealed a gestational sac located outside the uterine cavity but could not define its exact anatomic position. Using transvaginal 3-dimensional sonography, we were able to correctly depict the sac, which was located where the fallopian tube crossed the uterine horn. We performed a cornual resection, during which the diagnosis of interstitial pregnancy was confirmed. The use of 3-dimensional sonography in this patient's case thus led to appropriate early treatment and avoidance of possible subsequent morbidity.