title: Symptomatic patients with an early viable intrauterine pregnancy: HCG curves redefined.
abstract: OBJECTIVE
  To analyze the change in serial human chorionic gonadotropin (hCG) levels in women symptomatic with pain or bleeding who presented with nondiagnostic ultrasonography but were ultimately confirmed to have a viable intrauterine pregnancy.
  
  
  METHODS
  The rise in serial hCG measures were modeled over time, with the start point defined in 2 ways: by last menstrual period and by date of presentation for care. Both semiparametric (spline) curves and linear random-effects models were explored. The slope and projected increase of hCG were calculated to define 99% of viable intrauterine pregnancies.
  
  
  RESULTS
  A total of 287 subjects met inclusion criteria and contributed 861 measurements of hCG. On average, these subjects contributed 3.00 observations and were followed up for 5.25 days. A linear increase in log hCG best described the pattern of rise. Curves derived from last menstrual period and day of presentation do not differ substantially. The median slope for a rise of hCG after 1 day was 1.50, (or a 50% increase); 2.24 after 2 days (or a 124% rise), and 5.00 after 4 days. The fastest rise was 1.81 at 1 day, 3.28 at 2 days, and 10.76 at 4 days. The slowest or minimal rise for a normal viable intrauterine pregnancy was 24% at 1 day and 53% at 2 days.
  
  
  CONCLUSIONS
  These data define the slowest rise in serial hCG values for a potentially viable gestation and will aid in distinguishing a viable early pregnancy from a miscarriage or ectopic pregnancy. The minimal rise in serial hCG values for women with a viable intrauterine pregnancy is "slower" than previously reported, suggesting that intervention to diagnosis and treat an abnormal gestation should be more conservative.
authors.affiliation: Department of Obstetrics and Gynecology, University of Pennsylvania Medical Center, Philadelphia, Pennsylvania 19104, USA. kbarnhart@mail.obgyn.upenn.edu
authors.forename: Kurt T
authors.initials: KT
authors.lastname: Barnhart
authors.forename: Mary D
authors.initials: MD
authors.lastname: Sammel
authors.forename: Paolo F
authors.initials: PF
authors.lastname: Rinaudo
authors.forename: Lan
authors.initials: L
authors.lastname: Zhou
authors.forename: Amy C
authors.initials: AC
authors.lastname: Hummel
authors.forename: Wensheng
authors.initials: W
authors.lastname: Guo
mesh_terms: D000022:Abortion, Spontaneous / Q000175:diagnosis; D000293:Adolescent; D000328:Adult; D006063:Chorionic Gonadotropin / Q000097:blood*; D005260:Female; D006801:Humans; D015233:Models, Statistical; D011247:Pregnancy / Q000097:blood*; D011271:Pregnancy, Ectopic / Q000175:diagnosis
chemical_list: D006063:Chorionic Gonadotropin