Methotrexate (MTX) Therapy in Ectopic Pregnancy (EP)
Methotrexate Pharmacology in brief:
– MTX is a folic acid antagonist widely used for treatment of neoplasia, severe psoriasis & rheumatoid arthritis.
– Dose: 50 mg/m2 OR 1 mg/kg.
– Antidote: leucovorin (folinic acid), it rescue bone marrow & GIT mucosa from MTX.
– Routes of administration: the most common route is IM, but it can be given IV, IM, orally or by direct local injection into the EP sac transvaginally or laparoscopically.
– Adverse reactions: usually mild & self-limited in the form of stomatitis (commonest), conjunctivitis & elevated liver enzymes.
Methotrexate Indications:
– Hemodynamically stable EP.
– Desire for future fertility.
– hCG ≤5000 mIU/ml.
– EP mass size < 3-4 cm.
– No fetal cardiac activity.
Methotrexate Contraindications:
– Leucopenia (WBC <3000), thrombocytopenia (platelets <100,000) OR severe anemia.
– Active pulmonary disease & peptic ulcer:
– Heterotopic pregnancy with coexisting viable IUP.
– Breastfeeding.
– Suspected rupture EP.
– Relative contraindications: β-hCG >5000 mIU/ml, GS >3.5 cm & +ve cardiac activity.
– Liver enzymes >2 times normal OR creatinine >1.5 mg/dl as:
* MTX is renally cleared.
* In women with renal insufficiency, a single dose of MTX can lead to bone marrow suppression, acute respiratory distress (ARDS), bowel ischemia & even death.
* Renal & liver disease slows the metabolism of MTX & result in pancytopenia & skin & mucosal damage.
* Chronic renal disease or liver disease are contraindications.
Methotrexate Factors that decrease efficacy:
– High hCG concentration: is the most important factor associated with treatment failure. Women with hCG >5000 mIU/ml are more likely to require multiple courses of MTX or experience treatment failure.
– Fetal cardiac activity.
– Large EP size:
– Peritoneal fluid: U/S finding of free peritoneal fluid is an exclusion criterion for MTX treatment as it may be blood (tubal rupture or abortion).
– Isthmic location of the EP mass rather than ampullary (early rupture).
– High pretreatment folic acid level (will oppose MTX action).
Methotrexate Important points:
– The fertility rates after treatment of EP with salpingostomy, salpingectomy or MTX are similar.
– Treatment with MTX doesn’t appear to compromise ovarian reserve.
– Expectant management is contraindicated if the serum hCG is >200 mIU/ml. We treat these women with MTX or surgical therapy.
Best Regards