Ectopic pregnancy--potentials for diagnosis using ultrasound and urine and serum pregnancy tests.
The ultrasound findings from 260 patients with a clinical suspicion of ectopic pregnancy have been analysed and correlated with the results of urine pregnancy tests and tests of serum LH and/or HCG levels. Most importantly in a practical clinical context, it was found that a negative serum test virtually excludes an ectopic pregnancy, and an empty uterus with an adnexal mass and/or the presence of free fluid together with a positive urine test gives a very high probability of an ectopic pregnancy. The absolute diagnosis of an ectopic pregnancy by the demonstration of a living fetus outside the uterus is an uncommon finding (8%). Conversely, an empty uterus alone on ultrasound examination in the absence of other ultrasound findings in those patients with a positive serum test is not a reliable guide to the presence of an ectopic pregnancy unless there is an irrefutable conception date at least 5 weeks previously. It is recommended that pathology laboratories and ultrasound departments establish absolute levels of HCG above which an intrauterine pregnancy should always be visible within the uterus. Given appropriate attention to the clinical condition of the patient, the combined use of diagnostic ultrasound, simple urine pregnancy tests and serum assays of beta HCG levels goes a long way to discriminating between those patients with and those without an ectopic pregnancy.