How to measure size of tubal ectopic pregnancy on ultrasound

To identify the preoperative ultrasound parameters for assessing the size of tubal ectopic pregnancy that correlate best with findings at surgery.

This was a prospective study of all women attending our center who had a conclusive transvaginal ultrasound diagnosis of tubal ectopic pregnancy over a 10-month period. In each case, the total size of the ectopic pregnancy was measured by placing the calipers on the outer edges of the visible trophoblastic tissue. In ectopic pregnancies presenting with a well-defined gestational sac, the size of the celomic (chorionic) cavity was also measured using the inner borders of the trophoblastic ring as reference points. In women with signs of intra-abdominal bleeding, the size of the hematosalpinx and/or hemoperitoneum was measured. Surgeons were blinded to the ultrasound measurements and were asked to estimate the size of the ectopic pregnancy and the amount of hemoperitoneum intraoperatively.

A total of 105 women were diagnosed with a tubal ectopic pregnancy on ultrasound examination, of whom 71 (67.6%) were managed surgically. A significant (P < 0.01) positive correlation was found between all ultrasound measurements and the size of the tubal ectopic pregnancy as reported during surgery. In the absence of hematosalpinx, the mean total outer diameter of the ectopic pregnancy had the highest positive correlation with the size of the tubal ectopic pregnancy at surgery (r = 0.65, P < 0.001). In cases complicated by hematosalpinx, the mean diameter of the tube was the only variable that correlated significantly with the estimated size of the ectopic pregnancy at surgery (P < 0.001). There was a significant positive association between the amount of hemoperitoneum on ultrasound and the estimated volume of intraperitoneal blood at surgery (P < 0.001).

The mean size of a hematosalpinx and the total outer mean diameter of an ectopic pregnancy on ultrasound correlate better with the surgical findings than does the size of the celomic cavity. Our findings show that the standard approach of measuring the size of an intrauterine pregnancy on ultrasound should be adapted to include these additional measurements in women diagnosed with a tubal ectopic pregnancy. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.