Methotrexate Calculator for Ectopic Pregnancy
Methotrexate Calculator for Ectopic Pregnancy
Accurate MTX Dosage Calculation for Ectopic Pregnancy Treatment
Essential tool for OB/GYNs, emergency physicians, and healthcare providers
Calculate Methotrexate Dose
Enter patient details to calculate the recommended methotrexate dosage for ectopic pregnancy treatment.
Note: 1 kg = 2.2 lbs
Note: 1 cm = 0.3937 inches
Recommended Methotrexate Dose
This is an estimate based on standard protocols for ectopic pregnancy management.
Always confirm with clinical guidelines and patient-specific factors.
Calculation Methodology
BSA (m²) = √[ Height(cm) × Weight(kg) / 3600 ]
Dose = BSA × 50 mg/m²
Standard protocol: Single-dose intramuscular methotrexate 50 mg/m²
Methotrexate for Ectopic Pregnancy
What is Methotrexate?
Methotrexate (MTX) is a folic acid antagonist that inhibits rapidly dividing cells. It is used as a non-surgical treatment option for appropriately selected ectopic pregnancies.
Patient Selection Criteria
Methotrexate is appropriate when:
- Hemodynamically stable patient
- Unruptured ectopic pregnancy
- hCG levels < 5,000 mIU/mL (some protocols up to 15,000)
- Ectopic mass < 3.5-4.0 cm by ultrasound
- No fetal cardiac activity
- Normal renal and hepatic function
- Patient compliance with follow-up
Treatment Protocols
Single-Dose Protocol:
- Day 1: MTX 50 mg/m² IM
- Day 4: Measure hCG
- Day 7: Measure hCG
- Additional dose if hCG decrease < 15% between days 4-7
Two-Dose Protocol:
- Day 1: MTX 50 mg/m² IM
- Day 4: MTX 50 mg/m² IM
- Measure hCG on days 4, 6, and 7
Contraindications & Precautions
Methotrexate is contraindicated in:
- Breastfeeding women
- Immunodeficiency
- Active pulmonary disease
- Peptic ulcer disease
- Hepatic dysfunction (AST >2x normal)
- Renal dysfunction (creatinine >1.5 mg/dL)
- Sensitivity to methotrexate
Patients must avoid alcohol, NSAIDs, and folic acid supplements during treatment.
Frequently Asked Questions
What is the success rate of methotrexate for ectopic pregnancy?
The overall success rate for single-dose methotrexate treatment is approximately 70-95%. Success is higher when hCG levels are < 5,000 mIU/mL and there's no fetal cardiac activity.
How long does it take for hCG to reach zero after methotrexate?
hCG levels typically take 2-8 weeks to return to zero. The average time is 35 days, but this varies depending on initial hCG levels and individual patient factors.
What are the signs of treatment failure?
Signs requiring surgical intervention include: increasing abdominal pain, hemodynamic instability, rupture signs on ultrasound, or inadequate hCG decline (less than 15% between days 4-7).
When can a patient conceive after methotrexate treatment?
It’s recommended to wait until hCG reaches zero and then allow one full menstrual cycle (about 3 months total) before attempting conception. This allows the methotrexate to clear completely and endometrial lining to regenerate.