A prospective evaluation of a single-visit strategy to manage pregnancies of unknown location

BACKGROUND: The aim was to assess whether women with a pregnancy of unknown location (PUL) can be safely excluded from potentially unnecessary multiple clinic visits. METHODS: A single-visit protocol was developed based upon data from 200 consecutive PULs. PULs were divided into groups according to the probable risk of ectopic pregnancy. Those PULs with an initial serum progesterone <= 10 nmol/l or a serum HCG of <= 25 U/l were deemed to be at low risk and classified as resolving or failing PULs. Those PULs with an initial serum progesterone of >50 nmol/l, regardless of serum HCG, were thought to be a probable intra-uterine pregnancy (IUP) and were also classified as being low risk. Those PULs with an initial serum progesterone of 10-50 nmol/l and a serum HCG of >25 U/l were classified as being at high risk. This protocol was then tested prospectively on 318 consecutive PULs. Management was based solely on the basis of an initial transvaginal ultrasound scan (TVS) and a single measurement of HCG and progesterone taken at the time of initial consultation. RESULTS: A total of 5544 consecutive women were scanned, of which 560 (10.1%) women were classified as PULs. Forty-two were lost to follow-up and therefore 518 (9.34%) were analysed. In the training set of 200 PULs, there were 111 (55.5%) failing PULs, 67 (33.5%) IUPs and 22 (11%) ectopic pregnancies. In the test set of 318, there were 189 (59.4%) failing PULs, 114 (35.8%) IUPs and 15 (4.7%) ectopic pregnancies. For the training group, the sensitivity and specificity of a single visit to detect low-risk PULs were 77 and 82%, respectively. The positive (PPV) and negative predictive values (NPV) were 97 and 31%, respectively. For the test group of 318 PULs, the sensitivity and specificity were 84 and 33%, respectively. The PPV and NPV were 96 and 9.4%, respectively. CONCLUSIONS: A single-visit strategy based on commonly used criteria eliminates 84% of non-ectopic pregnancies correctly from the system. However, as 67% of ectopic pregnancies are discharged without adequate follow-up, a single-visit strategy should not be used as an alternative to the current multi-visit strategy used in most units.