There is no role for uterine curettage in the contemporary diagnostic workup of women with a pregnancy of unknown location.

Background: The aim of this study was to generate and evaluate a new protocol that defined non-viability in the pregnancy of unknown location (PUL) population and therefore ensured no viable intra-uterine pregnancy (IUP) would be interrupted if uterine curettage was performed. A secondary aim was to evaluate published biochemical criteria that define non-viability in a PUL population to establish if these criteria could result in inadvertent termination of pregnancy (TOP) if uterine curettage was performed.

Methods: All clinically stable women classified as having a PUL were included in this study. Protocol 1 was developed retrospectively based on data from 500 consecutive PULs. Using this protocol, no cases of viable IUPs would undergo uterine curettage and the potential for TOP was eliminated. This protocol was then validated prospectively on the data from a further 503 consecutive PULs. Results were then compared with three established criteria (Protocols 2-4) for the use of uterine curettage as a diagnostic tool to classify the location of PULs. Protocol 2 defined non-viability when the hCG ratio (hCG at 48 h/hCG at 0 h) was or=2000 U/l or when the initial serum hCG was <2000 U/l with a serum hCG rise of <35% over 48 h (hCG ratio<1.35); Protocol 4 advised uterine curettage with a serum hCG rise of <50% over 48 h (hCG ratio<1.50). The number of uterine curettages performed and viable IUPs that would have undergone an unplanned TOP were recorded for all protocols.

Results: A total of 12 572 consecutive women were scanned: 1003 (8.0%) women were classified as PULs. Training set consisted of 500 PULs: 278 (55.6%) failing PULs, 176 (35.2%) IUPs and 46 (9.2%) ectopic pregnancies (EPs). Test set consisted of 503 PULs: 255 (50.7%) failing PULs, 203 (40.4%) IUPs and 45 (9.0%) EPs. Protocol 1 when developed retrospectively on the training set would have resulted in 293 uterine curettages and no potential TOP. Protocol 1 tested prospectively on 503 PULs would have resulted in 272 uterine curettages and no potential TOP. Three established criteria were tested on the entire data set (n=1003). Protocol 2 would have resulted in 114 uterine curettages and 14 (12.3%) potential TOPs; Protocol 3 would have led to 611 uterine curettages and seven (1.2%) potential TOPs; Protocol 4 would have resulted in 617 uterine curettages and three (0.5%) potential TOPs. No harm came to the women whose EP diagnosis was delayed.

Conclusions: Established criteria for the use of uterine curettage in the management of PULs, including those advocated by the American Society for Reproductive Medicine (ASRM), can theoretically result in an inadvertent TOPs. On the basis of these data, a change in contemporary clinical practice should be considered to avoid further damage to wanted pregnancies. We conclude that uterine curettage should not be used in the routine diagnostic workup of women with a PUL.