{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,5]],"date-time":"2026-05-05T12:26:38Z","timestamp":1777983998069,"version":"3.51.4"},"reference-count":28,"publisher":"Wiley","issue":"4","license":[{"start":{"date-parts":[[2025,3,4]],"date-time":"2025-03-04T00:00:00Z","timestamp":1741046400000},"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":["Ultrasound in Obstet &amp;amp; Gyne"],"published-print":{"date-parts":[[2025,4]]},"abstract":"<jats:title>ABSTRACT<\/jats:title><jats:sec><jats:title>Objective<\/jats:title><jats:p>To analyze comprehensively the incidence, antenatal ultrasound characteristics and prognostic implications of antenatal pop\u2010off mechanisms of the fetal urinary system in pregnancies with suspected fetal megacystis.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>This was a retrospective multicenter study of pregnancies with suspected fetal megacystis conducted across all academic hospitals in The Netherlands. Three antenatal pop\u2010off mechanisms were identified: presence of an umbilical cord cyst (UCC), extravasation of urine into the intraperitoneal space (ascites) or perirenal subcapsular (urinoma), and megaureter\/ureterocele. Cases that exhibited two different pop\u2010off mechanisms, underwent vesicoamniotic shunt placement or had unclear information regarding shunt placement were excluded. We compared the antenatal ultrasound characteristics and outcomes among pregnancies with UCC, those with extravasation, those with megaureter\/ureterocele and those without a pop\u2010off mechanism. Logistic regression analysis was used to evaluate the association of pop\u2010off mechanisms with antenatal characteristics and postnatal outcomes.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>Among 543 fetuses with suspected megacystis, 76% exhibited no pop\u2010off mechanism, 7% presented with UCC only, 9% presented with extravasation only, 7% presented with a megaureter\/ureterocele only and 1% presented with two pop\u2010off mechanisms. Following exclusions, 511 cases were included in the analysis. The identification of UCC (<jats:italic>n<\/jats:italic>\u2009=\u200939) was associated with early\u2010onset megacystis (odds ratio (OR), 4.2 (95%\u2009CI, 1.9\u20139.1); <jats:italic>P<\/jats:italic>\u2009&lt;\u20090.001), severe megacystis (OR 2.3 (95%\u2009CI, 1.1\u20135.0); <jats:italic>P<\/jats:italic>\u2009=\u20090.033), normal amniotic fluid index (AFI) (OR, 3.3 (95%\u2009CI, 1.3\u20138.2); <jats:italic>P<\/jats:italic>\u2009=\u20090.011) and additional associated anomaly (OR, 3.3 (95%\u2009CI, 1.7\u20136.4); <jats:italic>P<\/jats:italic>\u2009&lt;\u20090.001), and thus with the highest prevalence of complex diagnosis (66%), primarily represented by anorectal malformation. Extravasation (<jats:italic>n<\/jats:italic>\u2009=\u200942) was associated with severe megacystis (OR, 2.4 (95%\u2009CI, 1.1\u20135.4); <jats:italic>P<\/jats:italic>\u2009=\u20090.030), abnormal AFI (OR, 2.8 (95%\u2009CI, 1.2\u20136.8); <jats:italic>P<\/jats:italic>\u2009=\u20090.022), the keyhole sign (OR, 2.5 (95%\u2009CI, 1.1\u20135.8); <jats:italic>P<\/jats:italic>\u2009=\u20090.033) and additional associated anomaly (OR, 2.1 (95%\u2009CI, 1.1\u20134.1); <jats:italic>P<\/jats:italic>\u2009=\u20090.026). Megaureter\/ureterocele (<jats:italic>n<\/jats:italic>\u2009=\u200936) was associated with late\u2010onset megacystis (OR, 4.0 (95%\u2009CI, 1.6\u20139.7); <jats:italic>P<\/jats:italic>\u2009=\u20090.003), a thickened bladder wall during pregnancy (OR, 6.6 (95%\u2009CI, 1.9\u201323.1); <jats:italic>P<\/jats:italic>\u2009=\u20090.003) and the lowest prevalence of additional associated anomaly (22%).<\/jats:p><jats:p>Intrauterine fetal demise was most prevalent in fetuses with UCC (15%), while termination of pregnancy and non\u2010survivors were most common in cases with extravasation (50% and 17%, respectively). The majority of fetuses with megacystis associated with megaureter\/ureterocele were still alive during follow\u2010up (72%) and the odds of survival were the highest for this group (OR, 2.7 (95%\u2009CI, 1.3\u20135.7); <jats:italic>P<\/jats:italic>\u2009=\u20090.010).<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusions<\/jats:title><jats:p>Antenatal pop\u2010off mechanisms may alleviate high intraluminal pressure within the fetal urinary tract. Each mechanism leads to a different antenatal clinical picture and outcome, which may explain partially the heterogeneity of outcomes in fetuses with megacystis. Therefore, understanding the implications of these mechanisms and their antenatal characteristics could guide antenatal counseling and management of fetal megacystis. \u00a9 2025 The Author(s). <jats:italic>Ultrasound in Obstetrics &amp; Gynecology<\/jats:italic> published by John Wiley &amp; Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.<\/jats:p><\/jats:sec>","DOI":"10.1002\/uog.29200","type":"journal-article","created":{"date-parts":[[2025,3,11]],"date-time":"2025-03-11T17:18:00Z","timestamp":1741713480000},"page":"487-494","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Pop\u2010off mechanisms in fetal megacystis: extravasation, umbilical cord cyst, ureterocele and megaureter"],"prefix":"10.1002","volume":"65","author":[{"ORCID":"https:\/\/orcid.org\/0009-0005-0789-7329","authenticated-orcid":false,"given":"L. A. M.","family":"Brinkman","sequence":"first","affiliation":[{"name":"Department of Obstetrics and Gynecology, University Medical Center Groningen University of Groningen  Groningen The Netherlands"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4089-9973","authenticated-orcid":false,"given":"L. K.","family":"Duin","sequence":"additional","affiliation":[{"name":"Department of Obstetrics and Gynecology, University Medical Center Groningen University of Groningen  Groningen The Netherlands"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"P. N.","family":"Adama van Scheltema","sequence":"additional","affiliation":[{"name":"Department of Obstetrics, Gynecology and Prenatal Diagnosis Leiden University Medical Center  Leiden The Netherlands"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9949-1476","authenticated-orcid":false,"given":"T. E.","family":"Cohen\u2010Overbeek","sequence":"additional","affiliation":[{"name":"Department of Obstetrics and Gynecology, Division of Obstetrics and Fetal Medicine Erasmus MC\u2010Sophia Children's Hospital University Medical Center  Rotterdam The Netherlands"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"E.","family":"Pajkrt","sequence":"additional","affiliation":[{"name":"Department of Obstetrics and Gynecology, Amsterdam University Medical Center University of Amsterdam  Amsterdam The Netherlands"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7372-4291","authenticated-orcid":false,"given":"M. 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T.","family":"Verweij","sequence":"additional","affiliation":[{"name":"Department of Obstetrics, Gynecology and Prenatal Diagnosis Leiden University Medical Center  Leiden The Netherlands"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1894-0626","authenticated-orcid":false,"given":"C.","family":"Bilardo","sequence":"additional","affiliation":[{"name":"Department of Obstetrics and Gynecology, University Medical Center Groningen University of Groningen  Groningen The Netherlands"},{"name":"Department of Obstetrics and Gynecology, Amsterdam University Medical Center University of Amsterdam  Amsterdam The Netherlands"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"F.","family":"Fontanella","sequence":"additional","affiliation":[{"name":"Department of Obstetrics and Gynecology, University Medical Center Groningen University of Groningen  Groningen The Netherlands"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"311","published-online":{"date-parts":[[2025,3,4]]},"reference":[{"key":"e_1_2_7_2_1","doi-asserted-by":"publisher","DOI":"10.1002\/uog.19182"},{"key":"e_1_2_7_3_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.ejogrb.2018.12.007"},{"key":"e_1_2_7_4_1","doi-asserted-by":"publisher","DOI":"10.1080\/15513815.2022.2158052"},{"key":"e_1_2_7_5_1","doi-asserted-by":"publisher","DOI":"10.7863\/jum.1999.18.2.95"},{"key":"e_1_2_7_6_1","doi-asserted-by":"publisher","DOI":"10.3389\/fped.2022.1014422"},{"key":"e_1_2_7_7_1","doi-asserted-by":"publisher","DOI":"10.5152\/tud.2013.016"},{"key":"e_1_2_7_8_1","doi-asserted-by":"publisher","DOI":"10.1007\/s00467-002-0862-x"},{"key":"e_1_2_7_9_1","doi-asserted-by":"publisher","DOI":"10.1046\/j.1469-0705.1997.08060387.x"},{"key":"e_1_2_7_10_1","doi-asserted-by":"publisher","DOI":"10.1002\/pd.4215"},{"key":"e_1_2_7_11_1","doi-asserted-by":"publisher","DOI":"10.1002\/uog.23647"},{"key":"e_1_2_7_12_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.ajog.2004.12.062"},{"key":"e_1_2_7_13_1","doi-asserted-by":"publisher","DOI":"10.1148\/rg.332125046"},{"key":"e_1_2_7_14_1","doi-asserted-by":"publisher","DOI":"10.1681\/ASN.2008030287"},{"issue":"356","key":"e_1_2_7_15_1","first-page":"e351","article-title":"Nadir creatinine in posterior urethral valves: how high is low enough?","volume":"11","author":"Coleman R","year":"2015","journal-title":"J Pediatr Urol"},{"key":"e_1_2_7_16_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.jpurol.2019.02.010"},{"key":"e_1_2_7_17_1","doi-asserted-by":"publisher","DOI":"10.7863\/jum.2010.29.2.295"},{"key":"e_1_2_7_18_1","volume-title":"Larsen's Human Embryology","author":"Schoenwolf GC","year":"2022"},{"key":"e_1_2_7_19_1","doi-asserted-by":"publisher","DOI":"10.1016\/S0029-7844(96)00526-1"},{"key":"e_1_2_7_20_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.bpobgyn.2014.01.009"},{"key":"e_1_2_7_21_1","doi-asserted-by":"publisher","DOI":"10.1080\/14767050500277602"},{"key":"e_1_2_7_22_1","doi-asserted-by":"publisher","DOI":"10.1016\/S0022-5347(17)41908-2"},{"key":"e_1_2_7_23_1","doi-asserted-by":"publisher","DOI":"10.1016\/S0022-5347(17)56435-6"},{"key":"e_1_2_7_24_1","doi-asserted-by":"publisher","DOI":"10.1016\/S0090-4295(74)80253-0"},{"key":"e_1_2_7_25_1","doi-asserted-by":"publisher","DOI":"10.1111\/j.1464-410X.1973.tb12173.x"},{"key":"e_1_2_7_26_1","doi-asserted-by":"publisher","DOI":"10.1002\/uog.2830"},{"key":"e_1_2_7_27_1","first-page":"394","article-title":"Fetal monolateral urinoma and neonatal renal function outcome in posterior urethral valves obstruction: the pop\u2010off mechanism","volume":"24","author":"Silveri M","year":"2002","journal-title":"Pediatr Med Chir"},{"key":"e_1_2_7_28_1","doi-asserted-by":"publisher","DOI":"10.1007\/BF02011386"},{"key":"e_1_2_7_29_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.eucr.2021.101697"}],"container-title":["Ultrasound in Obstetrics &amp; 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