[Medical management of interstitiel pregnancy by in situ methotrexate]

Interstitial pregnancy accounts for 3 to 11% of ectopic pregnancy; these pregnancies are the more frequently non-tubal ectopic pregnancy. Medical treatment can be used in case of unruptured interstitial pregnancy and is used more and more frequently to avoid hemorrhagic risk and risk of conversion to radical surgery when a surgical management is decided. However, a larger use of methotrexate in interstitial pregnancy and conditions of use are not clearly defined. The aim of this study is to report a series of unruptured interstitial pregnancy managed by in situ injection of methotrexate.

This retrospective observational study included women treated for an interstitial pregnancy between 2010 and 2013 in a teaching hospital. Medical management used was an in situ injection of methotrexate (1mg/kg) guided by vaginal sonography plus an intramuscular injection of methotrexate (1mg/kg) in the 48hours following in situ injection and 600mg of mifepristone when progesterone blood rate was more than 9ng/mL. A great decrease of serum hCG without surgery was considered a success.

Fourteen women had an interstitial pregnancy during the study period. Six were managed surgically in 5 cases for suspicion of uterine rupture and one for pregnancy of unknown location. Eight women had a medical management and the success rate was 100%. Mean time for decrease of serum hCG until 2 UI/L was 54.4 days [34.0-74.8]. No uterine rupture or immediate complication was reported. Five women out of 8 had a spontaneous pregnancy after management of interstitial pregnancy.

Medical management by in situ injection of methotrexate under sonographic guidance with an intramuscular injection within the 48hours following the in situ injection and mifepristone when ectopic pregnancy was active can be proposed in first-line therapy in case of unruptured interstitial pregnancy. This treatment has a great efficiency and low rate of complications.