{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,16]],"date-time":"2026-01-16T03:24:56Z","timestamp":1768533896019,"version":"3.49.0"},"reference-count":26,"publisher":"Wiley","issue":"2","license":[{"start":{"date-parts":[[2015,6,29]],"date-time":"2015-06-29T00:00:00Z","timestamp":1435536000000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":["obgyn.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Ultrasound in Obstet &amp;amp; Gyne"],"published-print":{"date-parts":[[2015,8]]},"abstract":"<jats:title><jats:styled-content style=\"fixed-case\">ABSTRACT<\/jats:styled-content><\/jats:title><jats:sec><jats:title>Objectives<\/jats:title><jats:p>To evaluate the diagnostic accuracy of ultrasound in predicting the location of an intrauterine pregnancy before visualization of the yolk sac is possible.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>This was a systematic review conducted in accordance with the <jats:styled-content style=\"fixed-case\">PRISMA<\/jats:styled-content> statement and registered with <jats:styled-content style=\"fixed-case\">PROSPERO<\/jats:styled-content>. We searched <jats:styled-content style=\"fixed-case\">MEDLINE<\/jats:styled-content>, <jats:styled-content style=\"fixed-case\">EMBASE<\/jats:styled-content> and The Cochrane Library for relevant citations. Studies were selected in a two\u2010stage process and their data extracted by two reviewers. Accuracy measures were calculated for each ultrasound sign, i.e. gestational sac, double decidual sac sign, intradecidual sign, chorionic rim sign and yolk sac. Individual study estimates were plotted in summary receiver\u2013operating characteristics curves and forest plots for examination of heterogeneity. The quality of included studies was assessed.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>Seventeen studies including 2564 women were selected from 19\u2009959 potential papers. Following meta\u2010analysis, the presence of a gestational sac on ultrasound examination was found to predict an intrauterine pregnancy with a sensitivity of 52.8% (95%\u2009<jats:styled-content style=\"fixed-case\">CI<\/jats:styled-content>, 38.2\u201366.9%) and specificity of 97.6% (95%\u2009<jats:styled-content style=\"fixed-case\">CI<\/jats:styled-content>, 94.3\u201399.0%). The corresponding performance of the double decidual sac sign, intradecidual sign, chorionic rim sign and yolk sac were: 81.8% (95%\u2009<jats:styled-content style=\"fixed-case\">CI<\/jats:styled-content>, 68.1\u201390.4%) and 97.3% (95%\u2009<jats:styled-content style=\"fixed-case\">CI<\/jats:styled-content>, 76.1\u201399.8%); 66.1% (95%\u2009<jats:styled-content style=\"fixed-case\">CI<\/jats:styled-content>, 58.9\u201372.8%) and 100% (95%\u2009<jats:styled-content style=\"fixed-case\">CI<\/jats:styled-content>, 91.0\u2013100%); 79.9% (95%\u2009<jats:styled-content style=\"fixed-case\">CI<\/jats:styled-content>, 73.0\u201385.7%) and 97.1% (95%\u2009<jats:styled-content style=\"fixed-case\">CI<\/jats:styled-content>, 89.9\u201399.6%); and 42.2% (95% CI, 27.7\u201357.9%) and 100% (95% CI, 54.1\u2013100%),  respectively.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusion<\/jats:title><jats:p>Visualization of a gestational sac, double decidual sac sign, intradecidual sign or chorionic rim sign increases the probability of an intrauterine pregnancy but is not as accurate for diagnosis as the detection of the yolk sac. However, the findings were limited by the small number and poor quality of the studies included and heterogeneity in the index test and reference standard. Copyright \u00a9 2014 ISUOG. Published by John Wiley &amp; Sons Ltd.<\/jats:p><\/jats:sec>","DOI":"10.1002\/uog.14725","type":"journal-article","created":{"date-parts":[[2014,11,13]],"date-time":"2014-11-13T06:38:55Z","timestamp":1415860735000},"page":"142-149","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":17,"title":["Accuracy of first\u2010trimester ultrasound in diagnosis of intrauterine pregnancy prior to visualization of the yolk sac: a systematic review and meta\u2010analysis"],"prefix":"10.1002","volume":"46","author":[{"given":"A.","family":"Richardson","sequence":"first","affiliation":[{"name":"Nurture Fertility The East Midlands Fertility Clinic  Nottingham UK"},{"name":"Division of Child Health, Obstetrics and Gynaecology, School of Medicine University of Nottingham  Nottingham UK"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"I.","family":"Gallos","sequence":"additional","affiliation":[{"name":"School of Clinical and Experimental Medicine, College of Medical and Dental Sciences University of Birmingham  Birmingham UK"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"S.","family":"Dobson","sequence":"additional","affiliation":[{"name":"Nottingham University Hospitals NHS Trust Queen's Medical Centre  Nottingham UK"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"B. 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