title: Methotrexate-treated ectopic pregnancy: beta human chorionic gonadotropin serum changes as a success predictor using a mathematical model validation.
abstract: BACKGROUND
  Surgical rescue of methotrexate-treated ectopic pregnancy is necessary when tubal rupture or medical therapy failure is detected during post-therapeutic monitoring. It is known that an increased beta human chorionic gonadotropin (β-hCG) concentration is the most important factor associated with treatment failure. Therefore, we suggested that relative changes in serum β-hCG could predict a successful result of medical treatment, leading to facilitation of the decision to forgo the prospect of possible surgical rescue.
  
  
  METHODS
  A retrospective observational study of 115 patients with an ectopic pregnancy who were treated with a single dosage protocol of 50mg/m2of methotrexate injected intramuscularly was performed at Puerta de Hierro University Hospital and Gregorio Marañón University General Hospital. Standard statistical tests were applied in order to evaluate the relative changes in β-hCG concentration between the 1st and the 4th days following methotrexate injection.
  
  
  RESULTS
  Methotrexate treatment has a 95% probability to be successful if the relative change of β-hCG from the 1st to the 4th day of monitoring is within the following interval: [-1.02; 0.15]. Moreover, if the values of β-hCG-relative change from 1st to 4th day of monitoring are within [0.54; 1.2], it assures a negative result of treatment with 95% probability. Therefore, the value 0.15 (15%) of β-hCG relative change can be considered a cut-off value for a positive result to treatment.
  
  
  CONCLUSIONS
  Our data support that negative β-hCG relative changes on the 4th day of treatment likely predict a successful result of methotrexate therapy, with a cut-off point of 0.15. Expectant management should be carried out in these cases if no clinical indications of surgery are presented.
authors.affiliation: University Hospital of Tajo, Spain. Electronic address: sasnad_84@hotmail.com.
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Kovaleva
authors.affiliation: Carlos III University, Madrid, Spain.
authors.forename: Natalia
authors.initials: N
authors.lastname: Irishina
authors.affiliation: Department of Obstetrics and Gynecology, University Hospital of Gregorio Marañón, Madrid, Spain.
authors.forename: Augusto
authors.initials: A
authors.lastname: Pereira
authors.affiliation: Department of Obstetrics and Gynecology, University Hospital of Gregorio Marañón, Madrid, Spain.
authors.forename: Tatiana
authors.initials: T
authors.lastname: Cuesta-Guardiola
authors.affiliation: Department of Obstetrics and Gynecology, University Hospital of Gregorio Marañón, Madrid, Spain.
authors.forename: Luis
authors.initials: L
authors.lastname: Ortiz-Quintana
mesh_terms: D000020:Abortifacient Agents, Nonsteroidal / Q000627:therapeutic use*; D015415:Biomarkers / Q000097:blood; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000097:blood*; D005260:Female; D006801:Humans; D008727:Methotrexate / Q000627:therapeutic use*; D011247:Pregnancy; D011271:Pregnancy, Ectopic / Q000097:blood / Q000188:drug therapy*; D012189:Retrospective Studies
chemical_list: D000020:Abortifacient Agents, Nonsteroidal; D015415:Biomarkers; D018997:Chorionic Gonadotropin, beta Subunit, Human; D008727:Methotrexate
keywords: Ectopic pregnancy; Methotrexate; Predictor; β-hCG