Predicting outcomes in pregnancies of unknown location.

A pregnancy of unknown location (PUL) is a descriptive term used to classify a woman when she has a positive pregnancy test but no intra- or extra-uterine pregnancy is visualized on transvaginal sonography. Expectant management has been shown to be safe for the majority of women with a PUL. Serum progesterone and human chorionic gonadotrophin levels as well as mathematical models play a role in predicting the final outcomes of PULs, which include intrauterine pregnancy, failing PUL and ectopic pregnancy. Other possible predictors of outcome have been studied, but currently no factor has been identified that combines accuracy with reproducibility and simplicity. This article discusses the various aspects of the management of women with PULs. Future work should be aimed at prospectively testing current models in order to predict the outcome of a PUL and minimizing follow-up.