Absolute contraindications to methotrexate include breast-feeding, evidence of immunodeficiency, blood dyscrasias including significant anemia, sensitivity to methotrexate, active pulmonary or pelvic ulcer disease, hepatic or renal dysfunction, or alcoholism. Kelly et al. reported a fatal outcome after methotrexate treatment for an ectopic pregnancy in a woman with renal insufficiency [10].

Up to 30 % of patients who receive a single dose of methotrexate and 40 % who receive multiple doses will experience side effects. The most common side effects are stomatitis and conjunctivitis, which are usually mild and self-limiting. Other rare side effects include pleuritis, dermatitis, alopecia, gastritis, enteritis, elevated liver enzymes, and bone marrow suppression. Therefore, even if there is no viable intrauterine pregnancy developing that is at risk for embryopathy, as in the case of a miscarriage, unnecessary methotrexate administration (or surgery) can cause unjustified morbidity to the patient.