{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,27]],"date-time":"2026-10-27T09:44:18Z","timestamp":1793094258561,"version":"4.5.0"},"reference-count":24,"publisher":"Wiley","issue":"3","license":[{"start":{"date-parts":[[2020,10,7]],"date-time":"2020-10-07T00:00:00Z","timestamp":1602028800000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["obgyn.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["BJOG"],"published-print":{"date-parts":[[2021,2]]},"abstract":"<jats:sec><jats:title>Objective<\/jats:title><jats:p>To validate externally five approaches to predict ectopic pregnancy (EP) in pregnancies of unknown location (PUL): the M6P and M6NP risk models, the two\u2010step triage strategy (2ST, which incorporates M6P), the M4 risk model, and beta human chorionic gonadotropin ratio cut\u2010offs (BhCG\u2010RC).<\/jats:p><\/jats:sec><jats:sec><jats:title>Design<\/jats:title><jats:p>Secondary analysis of a prospective cohort study.<\/jats:p><\/jats:sec><jats:sec><jats:title>Setting<\/jats:title><jats:p>Eight UK early pregnancy assessment units.<\/jats:p><\/jats:sec><jats:sec><jats:title>Population<\/jats:title><jats:p>Women presenting with a PUL and BhCG\u00a0&gt;25\u00a0IU\/l.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>Women were managed using the 2ST protocol: PUL were classified as low risk of EP if presenting progesterone\u00a0\u22642\u00a0nmol\/l; the remaining cases returned 2\u00a0days later for triage based on M6P. EP risk\u00a0\u22655% was used to classify PUL as high risk. Missing values were imputed, and predictions for the five approaches were calculated post hoc. We meta\u2010analysed centre\u2010specific results.<\/jats:p><\/jats:sec><jats:sec><jats:title>Main outcome measures<\/jats:title><jats:p>Discrimination, calibration and clinical utility (decision curve analysis) for predicting EP.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>Of 2899 eligible women, the primary analysis excluded 297 (10%) women who were lost to follow up. The area under the ROC curve for EP was 0.89 (95% CI 0.86\u20130.91) for M6P, 0.88 (0.86\u20130.90) for 2ST, 0.86 (0.83\u20130.88) for M6NP and 0.82 (0.78\u20130.85) for M4. Sensitivities for EP were 96% (M6P), 94% (2ST), 92% (N6NP), 80% (M4) and 58% (BhCG\u2010RC); false\u2010positive rates were 35%, 33%, 39%, 24% and 13%. M6P and 2ST had the best clinical utility and good overall calibration, with modest variability between centres.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusions<\/jats:title><jats:p>2ST and M6P performed best for prediction and triage in PUL.<\/jats:p><\/jats:sec><jats:sec><jats:title>Tweetable abstract<\/jats:title><jats:p>The M6 model, as part of a two\u2010step triage strategy, is the best approach to characterise and triage PULs.<\/jats:p><\/jats:sec>","DOI":"10.1111\/1471-0528.16497","type":"journal-article","created":{"date-parts":[[2020,9,21]],"date-time":"2020-09-21T18:54:46Z","timestamp":1600714486000},"page":"552-562","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":28,"title":["External validation of models to predict the outcome of pregnancies of unknown location: a multicentre cohort study"],"prefix":"10.1111","volume":"128","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-7900-5952","authenticated-orcid":false,"given":"E","family":"Christodoulou","sequence":"first","affiliation":[{"name":"Department of Development and Regeneration KU Leuven Leuven Belgium"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"S","family":"Bobdiwala","sequence":"additional","affiliation":[{"name":"Tommy's National Centre for Miscarriage Research Queen Charlotte's &amp; Chelsea Hospital Imperial College London UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"C","family":"Kyriacou","sequence":"additional","affiliation":[{"name":"Tommy's National Centre for Miscarriage Research Queen Charlotte's &amp; Chelsea Hospital Imperial College London UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"J","family":"Farren","sequence":"additional","affiliation":[{"name":"St Marys' Hospital London UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"N","family":"Mitchell\u2010Jones","sequence":"additional","affiliation":[{"name":"Chelsea and Westminster NHS Trust London UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"F","family":"Ayim","sequence":"additional","affiliation":[{"name":"Hillingdon Hospital London UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"B","family":"Chohan","sequence":"additional","affiliation":[{"name":"Wexham Park Hospital Slough UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"O","family":"Abughazza","sequence":"additional","affiliation":[{"name":"Royal Surrey County Hospital Guildford UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"B","family":"Guruwadahyarhalli","sequence":"additional","affiliation":[{"name":"Chelsea and Westminster NHS Trust London UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"M","family":"Al\u2010Memar","sequence":"additional","affiliation":[{"name":"Tommy's National Centre for Miscarriage Research Queen Charlotte's &amp; Chelsea Hospital Imperial College London UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"S","family":"Guha","sequence":"additional","affiliation":[{"name":"Chelsea and Westminster NHS Trust London UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"V","family":"Vathanan","sequence":"additional","affiliation":[{"name":"Wexham Park Hospital Slough UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"D","family":"Gould","sequence":"additional","affiliation":[{"name":"St Marys' Hospital London UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"C","family":"Stalder","sequence":"additional","affiliation":[{"name":"Tommy's National Centre for Miscarriage Research Queen Charlotte's &amp; Chelsea Hospital Imperial College London UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3037-122X","authenticated-orcid":false,"given":"L","family":"Wynants","sequence":"additional","affiliation":[{"name":"Department of Development and Regeneration KU Leuven Leuven Belgium"},{"name":"Department of Epidemiology CAPHRI Care and Public Health Research Institute Maastricht University Maastricht The Netherlands"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3707-6645","authenticated-orcid":false,"given":"D","family":"Timmerman","sequence":"additional","affiliation":[{"name":"Department of Development and Regeneration KU Leuven Leuven Belgium"},{"name":"Department of Obstetrics and Gynaecology University Hospitals Leuven Leuven Belgium"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1421-6059","authenticated-orcid":false,"given":"T","family":"Bourne","sequence":"additional","affiliation":[{"name":"Department of Development and Regeneration KU Leuven Leuven Belgium"},{"name":"Tommy's National Centre for Miscarriage Research Queen Charlotte's &amp; 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