Inclusion Criteria:  Diagnosis of tubal ectopic pregnancy. Pre-treatment beta-human chorionic gonadotrophin (β-hCG) level below 1500 mIU/ml. Gestational sac with largest diameter as 4cm. Willing to take methotrexate treatment. Willing to follow up.  Exclusion Criteria:  Heterotrophic pregnancy Persistent tubal pregnancy Embryonic cardiac motion Suspected tubal rupture Past history of harmful effects of methotrexate treatment on organ functions.