MAIN RESULTS AND THE ROLE OF CHANCE
tubal ectopic pregnancy
TUBAL ECTOPIC PREGNANCY
A total of 322 women with tubal ectopic pregnancy were treated with single-dose methotrexate. The overall single-dose methotrexate treatment success rate was 59% (n = 189/322). For any fall in serum hCG on Days 1–4, likelihood ratios were >3, while for any fall of serum hCG >20% on Days 1–7, likelihood ratios reached 5. Any rise of serum hCG on Days 1–7 and 4–7 strongly reduced the chance of success. Any fall in Days 1–4 hCG predicted single-dose methotrexate treatment success with a sensitivity of 58% and specificity 84%, resulting in positive and negative predictive values of 85% and 57%, respectively. Any rise in Days 1–4 serum hCG <18% was identified as an optimal test threshold that predicted treatment success with 79% sensitivity and 74% specificity, resulting in 82% positive predictive value and 69% negative predictive value.