title: Single point biochemical measurement algorithm for early diagnosis of ectopic pregnancy.
abstract: OBJECTIVE
  Tubal rupture as a result of an ectopic pregnancy is the leading cause of first trimester maternal mortality. Currently, the diagnosis of ectopic pregnancy depends on transvaginal ultrasound and serial serum measurements of human chorionic gonadotrophin (hCG), which requires follow up. The objective of this study was to examine whether single point measurements at presentation could distinguish between women with ectopic pregnancy, viable pregnancy, and spontaneous miscarriage.
  
  
  METHODS
  Serum total hCG (hCGt), hyperglycosylated hCG (hCGh), free beta subunit of hCG (hCGβ), progesterone (P), and CA-125 were measured by chemiluminescence immunoassay over a 3 month period in 441 women presenting at the emergency room with abdominal pain and a positive pregnancy test. Patient outcomes were followed and confirmed by histology. 65 samples were excluded due to poor sample storage, or lost to follow up.
  
  
  RESULTS
  The pregnancy outcomes were 175 viable pregnancies, 175 spontaneous miscarriages, and 26 ectopic pregnancies. A serum hCGt <3736 mIU/mL cut off was 100% sensitive, with 76% specificity, for distinguishing ectopic pregnancy from viable pregnancy; but did not differentiate spontaneous miscarriage. Serum CA125 <41.98 U/mL produced 100% sensitivity and 43% specificity in distinguishing ectopic pregnancy from spontaneous miscarriage. Sequential application of hCGt and CA-125 cut off followed by ultrasound could detect 100% of ectopic pregnancies with 87% specificity for all intrauterine pregnancies.
  
  
  CONCLUSIONS
  The combination of serum hCGt <3736 mIU/mL, followed by CA125 <41.98 U/mL is a promising algorithm for detecting all ectopic pregnancy at initial presentation.
authors.affiliation: School of Science and Technology, Middlesex University, The Burroughs, Hendon, London NW4 4BT, UK.
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Butler
authors.forename: Thomas K A
authors.initials: TK
authors.lastname: Abban
authors.forename: Paola T A
authors.initials: PT
authors.lastname: Borrelli
authors.forename: Jameel M
authors.initials: JM
authors.lastname: Luttoo
authors.forename: Bryn
authors.initials: B
authors.lastname: Kemp
authors.forename: Ray K
authors.initials: RK
authors.lastname: Iles
mesh_terms: D000022:Abortion, Spontaneous / Q000097:blood / Q000175:diagnosis*; D000328:Adult; D000465:Algorithms; D018394:CA-125 Antigen / Q000097:blood*; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000097:blood*; D042241:Early Diagnosis; D005260:Female; D006801:Humans; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011271:Pregnancy, Ectopic / Q000097:blood / Q000175:diagnosis*; D011374:Progesterone
chemical_list: D018394:CA-125 Antigen; D018997:Chorionic Gonadotropin, beta Subunit, Human; D011374:Progesterone
keywords: Biomarkers; CA125; Ectopic pregnancy; Progesterone; hCG; hCGβ