Rush Protocol for Treating Ectopic Pregnancy with Methotrexate
The Rush protocol for treating ectopic pregnancy consists of a multiple-dose methotrexate regimen of 1 mg/kg intramuscularly, alternating with leucovorin (folinic acid) rescue at 0.1 mg/kg. 1
Patient Selection Criteria
- Treatment is appropriate for hemodynamically stable patients with unruptured ectopic pregnancy ≤3.5 cm in greatest dimension 2
- Ideal candidates have β-hCG levels ≤5,000 mIU/mL and no embryonic cardiac activity on ultrasound 2
- Patients must be willing and able to comply with close follow-up monitoring 2
- Contraindications include alcoholism, immunodeficiency, peptic ulcer disease, active disease of lungs, liver, kidneys, or hematopoietic system 2
Protocol Details
- Pre-treatment laboratory testing required: complete blood count with differential and platelet counts, liver enzyme levels, and renal function tests 2
- The Rush protocol consists of:
- Treatment continues until β-hCG levels decline appropriately 1
- This differs from the single-dose protocol (50 mg/m²) which doesn't require leucovorin rescue 3
Monitoring and Follow-up
- β-hCG levels are monitored frequently (typically three times in the first week, then weekly) 3
- Treatment continues until β-hCG levels fall below 15 mIU/mL 3
- Patients should be monitored for side effects including nausea, vomiting, stomatitis, and elevated liver enzymes 4
Important Precautions
- Folic acid supplements should be avoided as they counteract methotrexate's mechanism of action 5
- Aspirin and NSAIDs should be avoided due to potentially lethal interactions with methotrexate 5
- For Rh-negative women, anti-D immunoglobulin should be administered due to risk of alloimmunization 2
Treatment Outcomes and Expectations
- The success rate of the multiple-dose regimen appears more effective than single-dose protocols, though they have not been directly compared 4
- Patients should be warned about potential rupture, which can occur even after treatment begins (median time to rupture is 14 days, maximum 32 days) 6
- Warning signs requiring immediate medical attention include severe abdominal pain, signs of hemodynamic instability, heavy vaginal bleeding, and shoulder pain 2
Side Effects and Complications
- Common side effects include nausea, vomiting, stomatitis, elevated liver function tests, anorexia, and diarrhea 4
- The most serious complication is ruptured ectopic pregnancy, which requires immediate surgical intervention 2
- Patients with higher β-hCG levels (>5,000 mIU/mL) or larger adnexal masses have higher failure rates and may require surgical intervention 6