Hum. Reprod. Advance Access published online on June 10, 2008
Human Reproduction, doi:10.1093/humrep/den221
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The hCG ratio can predict the ultimate viability of the intrauterine pregnancies of uncertain viability in the pregnancy of unknown location population
1 Early Pregnancy and Gynaecological Ultrasound Unit, Department of Obstetrics and Gynaecology, St George's, University of London, Cranmer Terrace, London SW17 0RE, UK 2 Acute Gynaecology and Early Pregnancy Unit, Nepean Centre for Perinatal Care, Nepean Clinical School, University of Sydney, Nepean Hospital, Penrith, Sydney, Australia 3 Omni Gynaecological Care, Women's Ultrasound and Early Pregnancy Centre, St Leonards, Sydney, Australia 4 Department of Electrical Engineering (ESAT), KU Leuven, Belgium 5 Department of Obstetrics and Gynaecology, University Hospital, Gasthuisberg, KU Leuven, Belgium
6 Correspondence address. Acute Gynaecology and Early Pregnancy Unit, Nepean Centre for Perinatal Care, Nepean Clinical School, University of Sydney, Nepean Hospital, Penrith, Sydney, Australia. E-mail: tommaso.bignardi{at}alice.it
BACKGROUND: To determine whether hCG ratio at 48 h can predict ultimate viability of intrauterine pregnancies of uncertain viability (IPUVs) in the pregnancy of unknown location (PUL) population.
METHODS: Prospective observational study from June 2001 to October 2004. All women classified with PUL had serum hCG levels measured at 0 and 48 h to calculate hCG ratio (hCG 48/hCG 0 h). All women were followed up until final diagnosis: failing PUL, viable and non-viable intrauterine pregnancy (IUP), ectopic pregnancy. Those PULs found to have an IPUV at follow-up transvaginal ultrasound scan (TVS) were included in final analysis.
RESULTS: During the study period, 12 572 consecutive first trimester women were scanned. One thousand and three (8%) women were classified PULs. Three hundred and seventy-nine (37.8%) PULs were confirmed IPUVs at follow-up scan. Complete data from 334 IPUVs were analyzed: 82.6% (276/334) viable IUPs and 17.4% (58/334) non-viable IUPs. Median hCG ratio was greater in viable IUPs [2.32, inter-quartile range (IQR) 1.16–4.77] compared with non-viable IUPs 1.83 (IQR 0.97–4.60). Sensitivity, specificity, positive and negative predictive value, positive and negative likelihood ratios of an hCG ratio >2.00 for the prediction of a viable IUP are 77.2%, 95.8%, 86.6%, 90.9%, 15.5, 0.24, respectively. In our population, an hCG ratio >2.00 increases the odds for a viable IUP from 0.42 to 6.46 post-test.
CONCLUSIONS: The hCG ratio is significantly higher in those IPUVs which become viable IUPs compared with non-viable IUPs. New cut-offs for the hCG ratio need to be evaluated for the prediction of viability in the IPUV group of PULs.
Key words: intrauterine pregnancy/pregnancy of unknown location/hCG/hCG ratio/pregnancy viability
Submitted on January 16, 2008; resubmitted on March 25, 2008; accepted on April 9, 2008.