The accuracy of transvaginal ultrasonography for the diagnosis of ectopic pregnancy prior to surgery

Abstract

Background: To evaluate the accuracy of transvaginal ultrasonography (TVS) for the detection of ectopic pregnancies (EPs) in women undergoing surgery for presumed ectopic pregnancy.

Methods: A prospective, observational study. Women were diagnosed with an EP using TVS if any of the following were noted in the adnexal region: (i) an inhomogeneous mass or blob sign adjacent to the ovary and moving separately from the ovary; or (ii) a mass with a hyper-echoic ring around the gestational sac or bagel sign; or (iii) a gestational sac with a fetal pole with or without cardiac activity. The final diagnosis was based on the findings at surgery and subsequent histology of removed tissues.

Results: 6621 consecutive women underwent TVS during the study; 200/6621 (3.0%) women were diagnosed as having an EP using TVS. Forty-eight non-surgically managed women were excluded from the analysis. 85.5% of women presented with symptoms and 14.5% were asymptomatic. In 88 (57.9%) cases an inhomogeneous mass or blob sign was visualized and in 20 cases (13.2%) an embryo +/- cardiac activity. Thirty-one (20.4%) had a hyper-echoic ring in the adnexa. In 11 (7.2%) cases there was no evidence of either an intra-uterine (IUP) or EP on ultrasound. Two (1.3%) IUPs were subsequently diagnosed as heterotopic pregnancies. There was no association between the presenting complaints and TVS findings. 152 surgical procedures were performed. In 5.9% (9/152) of these cases no EPs were confirmed in fallopian tube or pelvis at laparoscopy. In 9.1% (13/143) of cases an EP was visualized at surgery when not seen on the index ultrasound scan. The sensitivity and specificity of TVS to detect EP were 90.9% and 99.9%, respectively, with positive and negative predictive values of 93.5% and 99.8%, respectively.

Conclusions: 90.9% of ectopic pregnancies in this study population can be accurately diagnosed using TVS prior to surgery. The diagnosis of an ectopic pregnancy should be based on the positive visualization of an adnexal mass using TVS. This should in turn result in a decrease in the number of false positive laparoscopies.