Objective: To assess the results of expectant management in women with pregnancy of unknown location and to identify diagnostic parameters that are predictive of spontaneous pregnancy resolution.
Design: Prospective, observational study.
Subjects: Women with a positive pregnancy test and suspected early pregnancy complications who were referred for ultrasound assessment.
Methods: Women were first examined by transvaginal ultrasound to establish the location and viability of pregnancy. All women with pregnancies that could not be located on the scan had a blood sample taken to quantify the serum human chorionic gonadotropin (hCG) and progesterone levels. Management was expectant until the pregnancy was identified, the condition resolved spontaneously or an intervention was required because clinical symptoms deteriorated or hCG levels did not decline. For each woman, age, clinical symptoms (pain and bleeding), menstrual dates, past gynecological history, endometrial thickness and levels of serum hCG and progesterone were recorded. All parameters were tested by univariate analysis and then analyzed in a stepwise procedure to form a logistic regression model for predicting spontaneous resolution of pregnancy.
Results: A total of 1625 women were included in the study. In 135 cases (8%) the location of pregnancy was unknown. Complete data sets were obtained in 127 cases. These included 34 (27%) normal intrauterine pregnancies, 11 (9%) miscarriages and 18 (14%) ectopic pregnancies. A total of 64 (50%) pregnancies resolved spontaneously. Stepwise analysis showed that four diagnostic parameters--vaginal bleeding, endometrial thickness, serum hCG level and progesterone level--contributed significantly to the predictive power of the logistic model. With the use of this model, spontaneous pregnancy resolution could be predicted at the initial visit with a sensitivity and specificity of 92%.
Conclusions: The majority of pregnancies of unknown location are abnormal: many resolve spontaneously when managed expectantly. A logistic model may be used at the initial visit to identify those cases in which the pregnancy is likely to resolve without the need for intervention.