{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,29]],"date-time":"2026-10-29T18:34:24Z","timestamp":1793298864345,"version":"4.5.0"},"reference-count":28,"publisher":"Wiley","issue":"5","license":[{"start":{"date-parts":[[2014,9,15]],"date-time":"2014-09-15T00:00:00Z","timestamp":1410739200000},"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":[[2014,11]]},"abstract":"<jats:title>ABSTRACT<\/jats:title><jats:sec><jats:title>Objectives<\/jats:title><jats:p>To compare uterine artery pulsatility index (PI) obtained at 11\u2009+\u20090 to 13\u2009+\u20096\u2009weeks of gestation in singleton and twin pregnancies and to evaluate changes in PI values of twin pregnancies developing pre\u2010eclampsia (PE) or small\u2010for\u2010gestational age (SGA) of either one or both fetuses.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>Uterine artery PI was measured in 421 twin pregnancies (384 dichorionic and 37 monochorionic) and in 500 singleton pregnancies. The measured mean and lowest uterine artery PI values were converted to multiples of the expected normal median (MoM) after correction for maternal body mass index, ethnicity and gestational age. The median PI\u2010MoM values of twins were compared with those of singleton pregnancies. In twin pregnancies, PI\u2010MoM values were analyzed according to chorionicity, development of early\u2010onset (&lt;\u200934\u2009weeks) or late\u2010onset (\u2265\u200934\u2009weeks) PE and SGA of one or both twins.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>Uterine artery PI\u2010MoM was significantly lower in twin compared with singleton pregnancies (mean <jats:italic>K<\/jats:italic>\u2009=\u2009174.31, <jats:italic>P<\/jats:italic>\u2009&lt;\u20090.0001, lowest <jats:italic>K<\/jats:italic>\u2009=\u2009139.27, <jats:italic>P<\/jats:italic>\u2009&lt;\u20090.0001). However, there were no significant differences in the uterine artery PI\u2010MoM values between monochorionic and dichorionic twins. The uterine artery PI in twin pregnancies that developed early\u2010onset PE (<jats:italic>P<\/jats:italic>\u2009&lt;\u20090.001) and SGA of both twins (<jats:italic>P<\/jats:italic>\u2009&lt;\u20090.05) was higher than the uterine artery PI in uncomplicated twin pregnancies, whereas no differences were found for late PE or SGA of one twin.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusions<\/jats:title><jats:p>First\u2010trimester placental impedance to flow, as assessed by uterine artery Doppler examination, is reduced in twin pregnancies, with no differences related to chorionicity. The relative increase of uterine artery PI found in twin pregnancies that developed early PE and SGA of both twins suggests that first\u2010trimester uterine artery assessment may be useful in identifying such complications. Copyright \u00a9 2014 ISUOG. Published by John Wiley &amp; Sons Ltd.<\/jats:p><\/jats:sec>","DOI":"10.1002\/uog.13340","type":"journal-article","created":{"date-parts":[[2014,2,24]],"date-time":"2014-02-24T17:10:10Z","timestamp":1393261810000},"page":"557-561","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":34,"title":["Uterine artery Doppler evaluation in twin pregnancies at 11\u2009+\u20090 to 13\u2009+\u20096\u2009weeks of gestation"],"prefix":"10.1002","volume":"44","author":[{"given":"G.","family":"Rizzo","sequence":"first","affiliation":[{"name":"Fetal Medicine Center  Rome Italy"},{"name":"Department of Obstetrics and Gynecology Universit\u00e0 di Roma \u2018Tor Vergata\u2019  Rome Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"M. E.","family":"Pietrolucci","sequence":"additional","affiliation":[{"name":"Fetal Medicine Center  Rome Italy"},{"name":"Department of Obstetrics and Gynecology Universit\u00e0 di Roma \u2018Tor Vergata\u2019  Rome Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"E.","family":"Aiello","sequence":"additional","affiliation":[{"name":"Department of Obstetrics and Gynecology Universit\u00e0 di Roma \u2018Tor Vergata\u2019  Rome Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"A.","family":"Capponi","sequence":"additional","affiliation":[{"name":"Department of Obstetrics and Gynecology Ospedale G.B. Grassi  Rome Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"D.","family":"Arduini","sequence":"additional","affiliation":[{"name":"Department of Obstetrics and Gynecology Universit\u00e0 di Roma \u2018Tor Vergata\u2019  Rome Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2014,9,15]]},"reference":[{"key":"e_1_2_5_2_1","volume-title":"World Health Report","author":"World Health Organisation Collaboration","year":"2005"},{"key":"e_1_2_5_3_1","first-page":"569","article-title":"The \u2018Great Obstetrical Syndromes\u2019 are associated with disorders of deep placentation","volume":"25","author":"Brosens I","year":"2010","journal-title":"Am J Obstet Gynecol"},{"key":"e_1_2_5_4_1","doi-asserted-by":"publisher","DOI":"10.1046\/j.0960-7692.2001.00572.x"},{"key":"e_1_2_5_5_1","doi-asserted-by":"publisher","DOI":"10.1002\/uog.5157"},{"key":"e_1_2_5_6_1","doi-asserted-by":"publisher","DOI":"10.1016\/0028-2243(94)01982-D"},{"key":"e_1_2_5_7_1","doi-asserted-by":"publisher","DOI":"10.1016\/S0002-9378(00)70350-4"},{"key":"e_1_2_5_8_1","first-page":"89","article-title":"Risks of obstetric complications in multiple pregnancies: an analysis of more than 400 000 pregnancies in the UK","volume":"6","author":"Sebire NJ","year":"2001","journal-title":"Prenat Neonat Med"},{"key":"e_1_2_5_9_1","first-page":"978","article-title":"Uterine artery Doppler velocity waveforms in twin pregnancies","volume":"82","author":"Rizzo G","year":"1993","journal-title":"Obstet Gynecol"},{"key":"e_1_2_5_10_1","doi-asserted-by":"publisher","DOI":"10.1046\/j.1469-0705.2002.00865.x"},{"key":"e_1_2_5_11_1","doi-asserted-by":"publisher","DOI":"10.1046\/j.1469-0705.2002.00866.x"},{"key":"e_1_2_5_12_1","doi-asserted-by":"publisher","DOI":"10.1046\/j.1469-0705.1996.07060421.x"},{"key":"e_1_2_5_13_1","unstructured":"Nice Clinical Guidlines. 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