{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,12,9]],"date-time":"2025-12-09T08:24:26Z","timestamp":1765268666617,"version":"3.40.5"},"reference-count":17,"publisher":"Wiley","issue":"6","license":[{"start":{"date-parts":[[2020,6,15]],"date-time":"2020-06-15T00:00:00Z","timestamp":1592179200000},"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":["Aust NZ J Obst Gynaeco"],"published-print":{"date-parts":[[2020,12]]},"abstract":"<jats:sec><jats:title>Background<\/jats:title><jats:p>The prediction model M4 can successfully classify pregnancy of unknown location (PUL) into a low\u2010 or high\u2010risk group in developing ectopic pregnancy. M4 was validated in UK centres but in very few other countries outside UK.<\/jats:p><\/jats:sec><jats:sec><jats:title>Aim<\/jats:title><jats:p>To validate the M4 model\u2019s ability to correctly classify PULs in a cohort of Australian women.<\/jats:p><\/jats:sec><jats:sec><jats:title>Materials and Methods<\/jats:title><jats:p>A retrospective analysis of women classified with PUL, attending a Sydney\u2010based teaching hospital between 2006 and 2018. The reference standard was the final characterisation of PUL: failed PUL (FPUL) or intrauterine pregnancy (IUP; low risk) vs ectopic pregnancy (EP) or persistent PUL (PPUL; high risk). Each patient was entered into the M4 model calculator and an estimated risk of FPUL\/IUP or EP\/PPUL was recorded. Diagnostic accuracy of the M4 model was evaluated.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>Of 9077 consecutive women who underwent transvaginal sonography, 713 (7.9%) classified with a PUL. Six hundred and seventy\u2010seven (95.0%) had complete study data and were included. Final outcomes were: 422 (62.3%) FPULs, 150 (22.2%) IUPs, 105 (15.5%) EPs and PPULs. The M4 model classified 455 (67.2%) as low\u2010risk PULs of which 434 (95.4%) were FPULs\/IUPs and 21 (4.6%) were EPs or PPULs. EPs\/PPULs were correctly classified with sensitivity of 80.0% (95% CI 71.1\u201386.5%), specificity of 75.9% (95% CI 72.2\u201379.3%), positive predictive value of 37.8% (95% CI 33.8\u201342.1%) and negative predictive value of 95.3% (95% CI 93.1\u201396.9%).<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusions<\/jats:title><jats:p>We have externally validated the prediction model M4. It classified 67.2% of PULs as low risk, of which 95.4% were later characterised as FPULs or IUPs while still classifying 80.0% of EPs as high risk.<\/jats:p><\/jats:sec>","DOI":"10.1111\/ajo.13201","type":"journal-article","created":{"date-parts":[[2020,6,15]],"date-time":"2020-06-15T09:18:10Z","timestamp":1592212690000},"page":"928-934","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":3,"title":["External validation of risk prediction model M4 in an Australian population: Rationalising the management of pregnancies of unknown location"],"prefix":"10.1111","volume":"60","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-2926-4053","authenticated-orcid":false,"given":"Batool","family":"Nadim","sequence":"first","affiliation":[{"name":"Acute Gynaecology Early Pregnancy and Advanced Endoscopic Surgery Unit Nepean Hospital Nepean Clinical School University of Sydney Sydney New South Wales 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