{"id":4075,"date":"2024-07-03T15:57:00","date_gmt":"2024-07-03T15:57:00","guid":{"rendered":"https:\/\/www.osmosis.org\/blog\/?p=4075"},"modified":"2026-02-20T17:00:38","modified_gmt":"2026-02-21T01:00:38","slug":"usmle-step-1-question-of-the-day-quadruple-test","status":"publish","type":"post","link":"https:\/\/www.osmosis.org\/blog\/usmle-step-1-question-of-the-day-quadruple-test","title":{"rendered":"USMLE\u00ae Step 1 Question of the Day: Quadruple test"},"content":{"rendered":"<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_80 ez-toc-wrap-center counter-hierarchy ez-toc-counter ez-toc-custom ez-toc-container-direction\">\n<div class=\"ez-toc-title-container\">\n<p class=\"ez-toc-title\" style=\"cursor:inherit\">In This Article<\/p>\n<span class=\"ez-toc-title-toggle\"><a href=\"#\" class=\"ez-toc-pull-right ez-toc-btn ez-toc-btn-xs ez-toc-btn-default ez-toc-toggle\" aria-label=\"Toggle Table of Content\"><span class=\"ez-toc-js-icon-con\"><span class=\"\"><span class=\"eztoc-hide\" style=\"display:none;\">Toggle<\/span><span class=\"ez-toc-icon-toggle-span\"><svg style=\"fill: #999;color:#999\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" class=\"list-377408\" width=\"20px\" height=\"20px\" viewBox=\"0 0 24 24\" fill=\"none\"><path d=\"M6 6H4v2h2V6zm14 0H8v2h12V6zM4 11h2v2H4v-2zm16 0H8v2h12v-2zM4 16h2v2H4v-2zm16 0H8v2h12v-2z\" fill=\"currentColor\"><\/path><\/svg><svg style=\"fill: #999;color:#999\" class=\"arrow-unsorted-368013\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"10px\" height=\"10px\" viewBox=\"0 0 24 24\" version=\"1.2\" baseProfile=\"tiny\"><path d=\"M18.2 9.3l-6.2-6.3-6.2 6.3c-.2.2-.3.4-.3.7s.1.5.3.7c.2.2.4.3.7.3h11c.3 0 .5-.1.7-.3.2-.2.3-.5.3-.7s-.1-.5-.3-.7zM5.8 14.7l6.2 6.3 6.2-6.3c.2-.2.3-.5.3-.7s-.1-.5-.3-.7c-.2-.2-.4-.3-.7-.3h-11c-.3 0-.5.1-.7.3-.2.2-.3.5-.3.7s.1.5.3.7z\"\/><\/svg><\/span><\/span><\/span><\/a><\/span><\/div>\n<nav><ul class='ez-toc-list ez-toc-list-level-1 ' ><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/www.osmosis.org\/blog\/usmle-step-1-question-of-the-day-quadruple-test\/#The_correct_answer_to_todays_USMLE%C2%AE_Step_1_Question_is%E2%80%A6\" >The correct answer to today&#8217;s USMLE\u00ae Step 1 Question is&#8230;<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/www.osmosis.org\/blog\/usmle-step-1-question-of-the-day-quadruple-test\/#Incorrect_Answer_Explanations\" >Incorrect Answer Explanations<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/www.osmosis.org\/blog\/usmle-step-1-question-of-the-day-quadruple-test\/#Main_Explanation\" >Main Explanation<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/www.osmosis.org\/blog\/usmle-step-1-question-of-the-day-quadruple-test\/#Major_Takeaway\" >Major Takeaway<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"https:\/\/www.osmosis.org\/blog\/usmle-step-1-question-of-the-day-quadruple-test\/#References\" >References<\/a><\/li><\/ul><\/nav><\/div>\n\n<p class=\"wp-block-paragraph\"><em><strong>This USMLE Step 1 Question of the Day addresses abnormal lab results in a 17-week pregnant patient. Learn about the interpretation of quadruple test results and their implications.<\/strong><\/em><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">A <strong>39-year-old woman, gravida 1, para 0,<\/strong> comes to the office for the evaluation of <strong>abnormal laboratory results<\/strong>. The patient is at <strong>17 weeks gestation<\/strong> according to her last <strong>menstrual period.<\/strong> She used to <strong>drink 1 glass of wine<\/strong> on weekends during the <strong>first trimester<\/strong>, as she was unaware of the <strong>pregnancy<\/strong>. Past medical history is unremarkable. She regularly takes <strong>prenatal vitamins,<\/strong> and her <strong>immunizations are up to date<\/strong>. Results of the quadruple test are shown:\u00a0<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><tbody><tr><td><strong>Laboratory value&nbsp;<\/strong><\/td><td><strong>Result&nbsp;<\/strong><\/td><\/tr><tr><td>Maternal serum alpha fetoprotein&nbsp;<\/td><td>Low&nbsp;<\/td><\/tr><tr><td>Unconjugated estriol&nbsp;<\/td><td>Low&nbsp;<\/td><\/tr><tr><td>\u03b2-HCG&nbsp;<\/td><td>High&nbsp;<\/td><\/tr><tr><td>Inhibin A&nbsp;<\/td><td>High&nbsp;<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">The fetus is at greatest risk of developing <em>which of the following<\/em>?\u00a0<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>A. Myelomeningocele&nbsp;<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>B. Omphalocele&nbsp;<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>C. Fetal alcohol syndrome&nbsp;<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>D. Duodenal atresia<\/strong><strong>E. Gastroschisis&nbsp;<\/strong><\/p>\n\n\n\n<p class=\"has-text-align-center wp-block-paragraph\"><strong><em>Scroll down for the correct answer!<\/em><\/strong><\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"The_correct_answer_to_todays_USMLE%C2%AE_Step_1_Question_is%E2%80%A6\"><\/span>The correct answer to today&#8217;s USMLE\u00ae Step 1 Question is&#8230;<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>D. Duodenal atresia&nbsp;<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Before we get to the Main Explanation, let&#8217;s look at the incorrect answer explanations. Skip to the bottom if you want to see the correct answer right away!<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Incorrect_Answer_Explanations\"><\/span>Incorrect Answer Explanations<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>A. Myelomeningocele&nbsp;<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Incorrect:<\/strong>\u00a0Myelomeningocele results from a <strong>neural tube defect<\/strong> and causes increased <strong>maternal serum AFP<\/strong>, whereas unconjugated estriol, \u03b2-HCG and inhibin A is <strong>within normal limits<\/strong>.\u00a0<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>B. Omphalocele&nbsp;<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Incorrect:<\/strong>\u00a0Omphalocele can be seen in association with <strong>Trisomy 18.<\/strong> The quadruple test shows <strong>reduced levels<\/strong> of maternal serum AFP, <strong>unconjugated estriol, \u03b2-HCG and inhibin A<\/strong>. Neonates with <strong>Down syndrome<\/strong> are at slightly elevated risk of developing <strong>omphalocele<\/strong>; however, their risk for another gastrointestinal anomaly is greater.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>C. Fetal alcohol syndrome<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Incorrect:<\/strong>\u00a0Pregnant women should be advised to <strong>avoid alcohol intake during pregnancy.<\/strong> However, 1 glass of wine a week does not significantly increase the risk of <strong>fetal alcohol syndrome,<\/strong> and the results of this quadruple test suggest a different diagnosis.\u00a0<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>E. Gastroschisis&nbsp;<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Incorrect:<\/strong>\u00a0Gastroschisis results from an <strong>abdominal wall defect<\/strong> and causes <strong>increased maternal serum <\/strong>and <strong>amniotic fluid AFP<\/strong>, whereas unconjugated estriol, \u03b2-HCG and inhibin A are within normal limits.\u00a0<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Main_Explanation\"><\/span>Main Explanation<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">This pregnant patient\u2019s results from the <strong>quadruple test<\/strong> demonstrate an <strong>elevated hCG and inhibin A with low AFP and estriol<\/strong>; these findings are most indicative of <strong>Down syndrome (trisomy 21)<\/strong>. Down syndrome is the most common autosomal trisomy and the most frequent form of intellectual disability caused by a <strong>chromosomal aberration<\/strong>. It is characterized by the presence of an extra copy of genetic material on chromosome 21, either in whole (trisomy 21) or in part (such as due to translocations). \u00a0<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">A fetus with Down syndrome is at greatest risk of <strong>duodenal atresia<\/strong>, which results from the failure of canalization of the duodenum in early gestation. Affected infants present with <strong>bilious emesis<\/strong> during the first few days of life and \u201c<strong>double bubble<\/strong>\u201d sign (<strong>dilated stomach <\/strong>and <strong>proximal duodenum<\/strong>) on an abdominal x-ray. Other gastrointestinal abnormalities associated with Down syndrome include <strong>Hirschsprung disease, imperforate anus, tracheoesophageal fistula, <\/strong>and <strong>celiac disease.\u00a0<\/strong><\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"792\" height=\"1004\" src=\"https:\/\/www.osmosis.org\/blog\/wp-content\/uploads\/sites\/2\/2024\/09\/abdominal-xray-with-double-bubble-sign.png\" alt=\"Abdominal X-ray with Double Bubble signs\" class=\"wp-image-4077\" srcset=\"https:\/\/www.osmosis.org\/blog\/wp-content\/uploads\/sites\/2\/2024\/09\/abdominal-xray-with-double-bubble-sign.png 792w, https:\/\/www.osmosis.org\/blog\/wp-content\/uploads\/sites\/2\/2024\/09\/abdominal-xray-with-double-bubble-sign.png?resize=237,300 237w, https:\/\/www.osmosis.org\/blog\/wp-content\/uploads\/sites\/2\/2024\/09\/abdominal-xray-with-double-bubble-sign.png?resize=768,974 768w\" sizes=\"auto, (max-width: 792px) 100vw, 792px\" \/><figcaption class=\"wp-element-caption\">\u201cDouble bubble\u201d sign in a patient with duodenal atresia. Reproduced from:&nbsp;<a href=\"https:\/\/commons.wikimedia.org\/wiki\/File:DuodAtres.png\" target=\"_blank\" rel=\"noreferrer noopener\"><u>Wikimedia Commons<\/u><\/a><\/figcaption><\/figure>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" height=\"957\" width=\"1024\" src=\"https:\/\/www.osmosis.org\/blog\/wp-content\/uploads\/sites\/2\/2024\/09\/prenatal-trisomy-screenings.png?w=1024\" alt=\"PRENATAL TRISOMY SCREENINGS\n1st trimester screening\nTrisomy \/ B-hCG \/ PAPP-A\n21 \/ up \/ down\n18 \/ down \/ down\n13 \/ down \/ down\n\n2nd trimester screening\nTrisomy \/ B-hCG \/ Inhibin A \/ Estriol \/ AFP\n21 \/ up \/ up \/ down \/ down\n18 \/ down \/ - or down \/ down \/down\n13 \/ - \/ - \/ - \/ -\n\nReproduced from First Aid 2020\" class=\"wp-image-4076\" srcset=\"https:\/\/www.osmosis.org\/blog\/wp-content\/uploads\/sites\/2\/2024\/09\/prenatal-trisomy-screenings.png 1248w, https:\/\/www.osmosis.org\/blog\/wp-content\/uploads\/sites\/2\/2024\/09\/prenatal-trisomy-screenings.png?resize=300,280 300w, https:\/\/www.osmosis.org\/blog\/wp-content\/uploads\/sites\/2\/2024\/09\/prenatal-trisomy-screenings.png?resize=768,718 768w, https:\/\/www.osmosis.org\/blog\/wp-content\/uploads\/sites\/2\/2024\/09\/prenatal-trisomy-screenings.png?resize=1024,957 1024w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Major_Takeaway\"><\/span>Major Takeaway<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Duodenal atresia<\/strong>\u00a0is the <strong>most common gastrointestinal anomaly associated with Down syndrome. <\/strong>Affected infants present with bilious emesis during the first few days of life and \u201cdouble bubble\u201d\u00a0sign (dilated stomach and proximal duodenum) on an abdominal x-ray. Hirschsprung disease, imperforate anus, tracheoesophageal fistula, and celiac disease are other common associations of Trisomy 21.\u00a0<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"References\"><\/span>References<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Stoll, C., Dott, B., Alembik, Y., &amp; Roth, M. P. (2015). Associated congenital anomalies among cases with Down syndrome. European journal of medical genetics, 58(12), 674-680.&nbsp;<\/li>\n\n\n\n<li>Epstein CJ. Down syndrome (Trisomy 21). In: The metabolic and molecular bases of inherited disease, 8th ed, Scriver CR, Beaudet AL, Sly WS, Valle D (Eds), McGraw-Hill, New York 2001. p.1223.<\/li>\n<\/ul>\n\n\n\n<figure class=\"wp-block-image size-large\"><a href=\"https:\/\/www.osmosis.org\/ultimate-guide\/usmle-step-1\" target=\"_blank\" rel=\"noreferrer noopener\"><img loading=\"lazy\" decoding=\"async\" width=\"700\" height=\"250\" src=\"https:\/\/www.osmosis.org\/blog\/wp-content\/uploads\/sites\/2\/2024\/09\/the-ultimate-guide-usmle-step-1-banner.png?w=700\" alt=\"The Ultimate Guide to the USMLE Step 1: Everything you need to know\" class=\"wp-image-760\" srcset=\"https:\/\/www.osmosis.org\/blog\/wp-content\/uploads\/sites\/2\/2024\/09\/the-ultimate-guide-usmle-step-1-banner.png 700w, https:\/\/www.osmosis.org\/blog\/wp-content\/uploads\/sites\/2\/2024\/09\/the-ultimate-guide-usmle-step-1-banner.png?resize=300,107 300w\" sizes=\"auto, (max-width: 700px) 100vw, 700px\" \/><\/a><figcaption class=\"wp-element-caption\"><em><em><sub>The United States Medical Licensing Examination (USMLE\u00ae) is a joint program of the Federation of State Medical Boards (FSMB\u00ae) and National Board of Medical Examiners (NBME\u00ae). Osmosis is not affiliated with NBME nor FSMB.&nbsp;<\/sub><\/em><\/em><\/figcaption><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\"><em><strong>Want more USMLE\u00ae Step 1 practice questions? Try Osmosis by Elsevier today! Access your&nbsp;<\/strong><em><a href=\"https:\/\/www.osmosis.org\/login?type=create\" target=\"_blank\" rel=\"noreferrer noopener\"><strong>free trial<\/strong><\/a><\/em><strong>&nbsp;and find out why millions of current and future clinicians and caregivers love learning with us.<\/strong><\/em><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><\/p>\n","protected":false},"excerpt":{"rendered":"<p>A pregnant patient\u2019s quadruple test shows abnormal markers. Which fetal condition is most likely associated with these results?<\/p>\n","protected":false},"author":202,"featured_media":4083,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[27,20,16,1366,1369,44],"tags":[1941,1946,1943,1944,245,1945,1940,1942,664,1947],"class_list":["post-4075","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-medicine","category-exam-prep","category-do","category-questions","category-step-1-questions","category-step-1","tag-down-syndrome","tag-duodenal-atresia","tag-fetal-anomalies","tag-maternal-serum-alpha-fetoprotein","tag-nursing-education","tag-prenatal-screening","tag-quadruple-test","tag-trisomy-21","tag-usmle-step-1","tag--hcg"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v23.6 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>USMLE\u00ae Step 1 Question of the Day: Quadruple test - Osmosis Blog<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.osmosis.org\/blog\/usmle-step-1-question-of-the-day-quadruple-test\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"USMLE\u00ae Step 1 Question of the Day: Quadruple test - Osmosis Blog\" \/>\n<meta property=\"og:description\" content=\"A pregnant patient\u2019s quadruple test shows abnormal markers. 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