Predicting Outcomes in Pregnancies of Unknown Location

Emma Kirk; Tom Bourne


Women's Health. 2008;4(5):491-499. 

In This Article

Number of Visits

As previously mentioned, neither the sole use of a single progesterone level nor a single hCG measurement, as used when applying a discriminatory zone, is useful in the prediction of ectopic pregnancy in women with a PUL. A single-visit strategy based on the initial serum progesterone in combination with the initial serum hCG level to categorize women into being at either high or low risk of ectopic pregnancy has also been developed and tested prospectively on a total of 518 PULs.[35] While it correctly eliminated 84% of nonectopic pregnancies from further follow-up, its safety was challenged since 67% of ectopic pregnancies would also have been discharged without adequate follow-up. Therefore, current research suggests that more than one visit is necessary to successfully predict ectopic pregnancy within the PUL population.

Although there are strategies, such as the use of mathematical models that enable the location of the pregnancy to be predicted within 48h, in reality, in many cases it is often significantly longer before the true location of the pregnancy is confirmed after either TVS or surgical intervention, in the form of either laparoscopy or surgical uterine evacuation. At present, there is no standardized protocol for follow-up. During this time period, women may have multiple blood tests in order to measure serum hCG and progesterone levels and undergo numerous TVS examinations until the pregnancy is visualized or hCG levels decrease. This represents a significant workload for clinicians and is inconvenient for patients.

A recently published, prospective study aimed to rationalize the follow-up of women with PULs by managing them according to a protocol based on the predictions of a mathematical model.[7] Almost 90% of the women included were successfully managed according to the set protocol, with the majority of IUPs (80.2%) being confirmed on the basis of two ultrasound scans and two serum hCG measurements within 7days±1day, and the majority of failing PULs (93.0%) being confirmed within 2days after only one TVS examination and two serum hCG measurements. The majority of ectopic pregnancies (87%) were diagnosed within 7days. Overall, more than 60% of PULs could be eliminated from further follow-up at 48 h. By 7days after presentation, only 2.5% of women remained classified as PULs. Further studies are now needed to test the reproducibility of such models and follow-up protocols in other units. Seeber etal. have also demonstrated that the time to diagnosis of an ectopic pregnancy can be decreased by 2.5 days with the use of hCG curves compared with conventional clinical management.[16]


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