Classification of tubal gestations by transvaginal sonography

Abstract

Transvaginal sonographic images of tubal pregnancies were correlated with the surgical findings in 191 patients having this condition. The sonographic appearance of the ectopic gestations was classified by the absence or presence of structures such as a 'tubal ring' containing the yolk sac, embryonic structures, heart activity, a sonolucent or irregularly echogenic gestational sac, dilated Fallopian tube with amorphous content, fluid in the pelvis and an empty uterus. The following classifications were made: Type Ia (n = 43) A well-defined 'tubal ring' and a beating heart with or without discrete embryonic or extra-embryonic structures. Type Ib (n = 48) A 'tubal ring' containing embryonic and/or extra-embryonic structures without heart beats. Type II (n = 64) An ill-defined or thin tubal wall containing sonolucent or an irregularly echogenic core but not embryonic or extra-embryonic structures. Type III (n = 28) Free pelvic fluid and an empty uterus in patients with positive serum beta-hCG levels. The outline of the tube cannot be visualized. Surgery revealed unruptured tubal pregnancies in 90 patients of the combined groups of Types Ia and Ib. In one additional patient, a tubal rupture was found. In the Type II patients, 26 tubal pregnancies with blood clots in the tube but no evidence of bleeding into the pelvis, and 38 tubal ruptures or abortions were diagnosed. All Type III patients had ruptured tubal pregnancies or bleeding tubal abortions. In eight patients (4.2%), the only sonographic finding was an empty uterus, and these cases were erroneously diagnosed as not having an ectopic pregnancy (false negatives). There were two false-positive cases in which a tubal ring was detected, and this was related to an hemorrhagic corpus luteum. When used for diagnosing tubal pregnancy, the transvaginal scanning technique (together with beta-hCG in Type III cases) carries a sensitivity of 95.8% and specificity of 99.9%. It is an invaluable tool in the diagnostic work-up and management of patients with suspected ectopic gestation.