Ultrasound evaluation of ectopic pregnancy

Abstract

Ectopic pregnancy, the implantation of a fertilized ovum outside the uterine cavity, now accounts for 2 % of all pregnancies in the United States. Nearly all ectopic pregnancies (97 %) are implanted within the fallopian tube, and a common factor for the development of such ectopics is the presence of a pathological fallopian tube. Ectopic implantation can also occur outside of the fallopian tube, within the cervix, ovary, abdomen, uterine cornua, and cesarean scars. These extratubal implantations may not be associated with tubal pathology or the expected preexisting risk factors for tubal ectopic implantation. The imaging modality of choice for the diagnosis of early pregnancy, regardless of implantation site, is transvaginal ultrasound. Early transvaginal ultrasound can locate most, if not all early pregnancies, and should be performed on every early pregnancy with symptoms of gestational pathology or a high likelihood of ectopic pregnancy based on gynecologic history.