This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Ecotopic Pregnancy, Subject name: Gynaecology & Obstetrics
Methotrexate is best suited when b-hCG concentration is: 
Select and explain. 
A. <5000 IU, B. <6000 IU, C. <7000 IU, D. <10,000 IU
A: <5000 IU
Answer: A: <5000 IU 
Explanation: Ans. is a, i.e. < 5000 IU.(Ref. Williams Obs 25/e pg 378)Failure rate of methotrexate is 3.8%. If b-hCG levels are < 5000 IU but rise to 14% if levels are between 5000-10,000.