It is hypothesized that the inhibition of estradiol production by letrozole may interfere with physiological effects of progesterone necessary to maintain the pregnancy. Treatment of tubal pregnancy with letrozole would allow to avoid the adverse effects of methotrexate (MTX) in women refusing surgery. The aim was to compare the effectiveness of letrozole with MTX in the management of tubal pregnancy.

A prospective cohort study is conducted among women with tubal pregnancy. Women with increasing B-human chorionic gonadotropin (B-hCG) concentrations are included.

Two study arms were planned:

i) women treated with MTX: MTX in a single dose of 100 mg intravenously on day 0; ii) women treated with letrozole: letrozole at a daily dose of 5 mg orally for 10 days from day 0.

The inclusion criteria included B-hCG concentration up to 3000 mIU/ml and no contraindications to conservative treatment. Women who did not meet criteria for conservative treatment were excluded. Blood parameters (B-hCG, hemoglobin, creatinine, urea, alanine/aspartate transaminase, gamma-glutamyltransferase, bilirubin) were tested on days 0,4,7. Cases of treatment failure were counted, i.e. the need to perform laparoscopy due to tubal pregnancy rupture, pain, increase in B-hCG concentration.

The women were given the option to choose the treatment used in the study. All enrolled women gave informed written consent to participate in the study.

Inclusion Criteria:

• tubal pregnancy confirmed on pelvic ultrasound
• increasing serum B-hCG concentrations in at least two subsequent measures
• serum B-hCG concentration ≤ 3000 mIU/ml

Exclusion Criteria:

• free fluid in lesser pelvis on pelvic ultrasound
• positive fetal heartbeat on pelvic ultrasound
• abdominal pain
• heterotopic pregnancy
• contraindications to MTX