Diagnosis of ectopic pregnancy by vaginal ultrasonography in combination with a discriminatory serum hCG level of 1000 IU/l (IRP).

The diagnostic value of vaginal sonography in combination with a discriminatory serum hCG level of 1000 iu/l (International Reference Preparation) was tested prospectively in 200 pregnant women suspected of having an ectopic pregnancy. An ectopic pregnancy was diagnosed in 68 women (34%), a miscarriage in 56 (28%) and a normal pregnancy in 76 (38%). On admission, an intrauterine sac was seen in 89% of the intrauterine pregnancies, but in none of the ectopic pregnancies. Detection of an adnexal mass separate from the ovaries was diagnostic of ectopic pregnancy with a sensitivity of 93%, a specificity of 99%, a positive predictive value of 98% and a negative predictive value of 96%. In 19 patients (9%) the initial sonogram was non-diagnostic and the final diagnosis was obtained after a repeated scan within 6 days. Five of these women had an ectopic pregnancy, 12 a miscarriage and two a normal pregnancy. On admission the hCG level exceeded 1000 iu/l in 77% of all patients and in 67% of those with ectopic pregnancies. In patients with an initial level exceeding 100 iu/l, an intrauterine sac was found in all the intrauterine pregnancies but in none of the ectopic pregnancies. The use of this threshold in combination with sonographic detection of an adnexal mass was diagnostic of ectopic pregnancy with a sensitivity of 97%, a specificity of 99%, a positive predictive value of 98% and a negative predictive value of 98%.