title: Early and late half-life of human chorionic gonadotropin as a predictor of persistent trophoblast after laparoscopic conservative surgery for tubal pregnancy.
abstract: BACKGROUND
  To determine if the early or late half-lives (T0.5) of human chorionic gonadotropin (hCG) can identify patients with persistent trophoblastic activity after conservative surgery for tubal pregnancy.
  
  
  METHODS
  Prospective cohort study.
  
  
  METHODS
  Department of obstetrics and gynecology of a university hospital.
  
  
  METHODS
  All patients with a tubal pregnancy treated by laparoscopic salpingostomy between June 1997 and September 2000 were enrolled in the study. Postoperative sequential hCG sampling was performed at days 0, 2 (+/- 1) and 7 (+/- 2) and followed until levels were undetectable. Taking the biexponential hCG declining curve as a model, we calculated the early (days 0-2) and late (days 2-7) T0.5 hCG values.
  
  
  METHODS
  To assess success or failure of surgical treatment.
  
  
  RESULTS
  Seventy-three patients with an ectopic pregnancy were managed by conservative surgery. Early and late T0.5 allowed us to identify 2/10 and 9/10 women, respectively, with persistent trophoblast. Late T0.5 levels revealed two patients with false-positive values, but one patient showed a secondary increase in hCG after day 7 (false-negative) despite a normal late T0.5.
  
  
  CONCLUSIONS
  Early and late half-lives of hCG do not identify all women at risk for persistent ectopic pregnancy. To exclude persistent trophoblast, postoperative serum hCG determination should be performed until levels are undetectable.
authors.affiliation: Department of Gynecology and Obstetrics, University Hospitals of Geneva, Geneva, Switzerland. marie-helene.billieux@hcuge.ch
authors.forename: Marie-Hélène
authors.initials: MH
authors.lastname: Billieux
authors.forename: Patrick
authors.initials: P
authors.lastname: Petignat
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Anguenot
authors.forename: Aldo
authors.initials: A
authors.lastname: Campana
authors.forename: Paul
authors.initials: P
authors.lastname: Bischof
mesh_terms: D000293:Adolescent; D000328:Adult; D015415:Biomarkers / Q000032:analysis; D006063:Chorionic Gonadotropin / Q000032:analysis / Q000493:pharmacokinetics*; D005189:False Positive Reactions; D005260:Female; D006207:Half-Life; D006801:Humans; D010535:Laparoscopy; D011237:Predictive Value of Tests; D011247:Pregnancy; D011271:Pregnancy, Ectopic / Q000473:pathology / Q000601:surgery*; D012307:Risk Factors; D014327:Trophoblasts
chemical_list: D015415:Biomarkers; D006063:Chorionic Gonadotropin