From the Guidelines
Renal insufficiency is a contraindication to methotrexate therapy for ectopic pregnancy. Methotrexate is primarily eliminated by the kidneys, so impaired renal function can lead to drug accumulation, resulting in increased toxicity and serious adverse effects 1. The other options listed (Beta-hCG < 5,000 mIU/mL, ectopic gestational sac < 3.5 cm, and no fetal cardiac activity) are actually favorable criteria for methotrexate treatment, as they indicate scenarios where medical management is likely to be successful. Patients with lower beta-hCG levels, smaller ectopic masses, and absence of fetal cardiac activity typically have better outcomes with methotrexate therapy.
Key Considerations
- Before administering methotrexate, clinicians should assess renal function through blood tests and avoid using this medication in patients with significant renal impairment 1.
- Other contraindications to methotrexate include moderate to severe anemia, leukopenia, thrombocytopenia, active liver disease, breastfeeding, immunodeficiency, and known sensitivity to methotrexate 1.
- The use of a test dose of methotrexate is mandatory in patients with a decreased glomerular filtration rate or other significant risk factors for hematologic toxicity 1.
Monitoring and Precautions
- Serum urea nitrogen (BUN) and creatinine should be obtained at 2- to 3-month intervals 1.
- Liver chemistries including alanine aminotransferase, AST, alkaline phosphatase, and serum albumin levels should be performed every 4 weeks 1.
- More frequent monitoring is suggested with dosage increases, as pancytopenia may occur as long as 4 to 6 weeks after increasing the methotrexate dosage 1.
From the FDA Drug Label
Methotrexate elimination is reduced in patients with impaired renal functions, ascites, or pleural effusions. Methotrexate has been reported to cause fetal death and/or congenital anomalies. Pregnant women with psoriasis or rheumatoid arthritis should not receive methotrexate (See CONTRAINDICATIONS).
The answer is Renal insufficiency. Methotrexate elimination is reduced in patients with impaired renal functions, which may lead to increased toxicity. 2
From the Research
Contraindications to Methotrexate Therapy
- Renal insufficiency is a contraindication to methotrexate therapy for ectopic pregnancy, as methotrexate is excreted predominantly by the kidney and can be fatal in patients with renal insufficiency 3, 4, 5, 6
Acceptable Conditions for Methotrexate Therapy
- Beta-hCG < 5,000 mIU/mL is not a contraindication to methotrexate therapy, but rather a consideration for the treatment of ectopic pregnancy 7
- Ectopic gestational sac < 3.5 cm is not a contraindication to methotrexate therapy, but rather a consideration for the treatment of ectopic pregnancy
- No fetal cardiac activity is not a contraindication to methotrexate therapy, but rather a predictive factor for success of the treatment 7