Single point biochemical measurement algorithm for early diagnosis of ectopic pregnancy

• Published in: Clinical biochemistry Vol. 46; no. 13-14; pp. 1257 - 1263
• Main Authors: Butler, Stephen A., Abban, Thomas K.A., Borrelli, Paola T.A., Luttoo, Jameel M., Kemp, Bryn, Iles, Ray K.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01-09-2013
• Subjects: Abortion, Spontaneous - blood; Abortion, Spontaneous - diagnosis; Adult; Algorithms; Biomarkers; CA-125 Antigen - blood; CA125; Chorionic Gonadotropin, beta Subunit, Human - blood; Early Diagnosis; Ectopic pregnancy; Female; hCG; hCGβ; Humans; Pregnancy; Pregnancy Trimester, First; Pregnancy, Ectopic - blood; Pregnancy, Ectopic - diagnosis; Progesterone; Biomarkers; CA125; Progesterone; Ectopic pregnancy; hCG; hCGβ
• ISSN: 0009-9120; 1873-2933
• DOI: 10.1016/j.clinbiochem.2013.06.019

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.
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 3month 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.
The pregnancy outcomes were 175 viable pregnancies, 175 spontaneous miscarriages, and 26 ectopic pregnancies. A serum hCGt <3736mIU/mL cut off was 100% sensitive, with 76% specificity, for distinguishing ectopic pregnancy from viable pregnancy; but did not differentiate spontaneous miscarriage. Serum CA125 <41.98U/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.
The combination of serum hCGt <3736mIU/mL, followed by CA125 <41.98U/mL is a promising algorithm for detecting all ectopic pregnancy at initial presentation.
•Tubal rupture due to ectopic pregnancy is a leading cause of maternal mortality.•A single point measurement at presentation to distinguish ectopic pregnancy•A serum hCGt <3736mIU/mL distinguished ectopic from viable pregnancies.•Serum CA125 <41.98U/mL distinguished ectopic pregnancy from spontaneous miscarriage.•hCGt with CA125 has 100% sensitivity and 75% specificity for ectopic pregnancy.