Final answer:
Methotrexate is used to manage early ectopic pregnancies by arresting the growth of embryonic cells. Approximately 50% of tubal pregnancies not resolving spontaneously may require it. The treatment success rate is favorable with early diagnosis and proper patient selection.
Step-by-step explanation:
The question asks about the success rate of methotrexate in managing early ectopic pregnancy. An ectopic pregnancy occurs when a fertilized egg implants and grows outside the main cavity of the uterus, often in a fallopian tube. Methotrexate works by inhibiting the metabolism of folic acid, essential for DNA synthesis and cell replication, thereby arresting the growth of rapidly dividing embryonic, trophoblastic, and fetal cells. It's considered a less invasive treatment option as compared to surgery.
While specific success rates can vary depending on the extent of the condition and other patient factors, methotrexate can be highly effective if the ectopic pregnancy is diagnosed early before the fallopian tube is damaged. Approximately half of tubal pregnancies that do not resolve spontaneously may require such medical intervention with methotrexate. However, if the diagnosis is late and a ruptured tube occurs, surgical intervention becomes necessary. For the cases suitable for methotrexate treatment, the success rate is quite favorable but is also contingent on careful selection of patients and monitoring.