{"id":386,"date":"2020-08-13T20:21:25","date_gmt":"2020-08-13T20:21:25","guid":{"rendered":"https:\/\/brooksidepress.org\/basic_obgyn\/?page_id=386"},"modified":"2020-10-20T17:02:24","modified_gmt":"2020-10-20T17:02:24","slug":"multiple-gestation","status":"publish","type":"page","link":"https:\/\/brooksidepress.org\/basic_obgyn\/advanced-training\/multiple-gestation\/","title":{"rendered":"Multiple Gestation"},"content":{"rendered":"<p><iframe loading=\"lazy\" src=\"https:\/\/www.youtube.com\/embed\/4EKrNaMn7v4\" width=\"560\" height=\"315\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\"><\/iframe><\/p>\n<p>Duration 10:10<\/p>\n<input type='hidden' bg_collapse_expand='69e9c848cdcdb0006067163' value='69e9c848cdcdb0006067163'><input type='hidden' id='bg-show-more-text-69e9c848cdcdb0006067163' value='Show Teaching Transcript'><input type='hidden' id='bg-show-less-text-69e9c848cdcdb0006067163' value='Hide Teaching Transcript'><button id='bg-showmore-action-69e9c848cdcdb0006067163' class='bg-showmore-plg-button bg-blue-button  '   style=\" color:#ffffff;\">Show Teaching Transcript<\/button><div id='bg-showmore-hidden-69e9c848cdcdb0006067163' ><\/p>\n<p>Multiple Gestation Pregnancies<\/p>\n<p>Liang A<\/p>\n<p>Clinical Cases Applicability: Twin and higher order multiples pregnancy, IVF, TTTS<\/p>\n<p>Learning Objectives:<\/p>\n<p>1) Describe early fetal development from fertilization to implantation<\/p>\n<p>2) Understand the physiology of twinning<\/p>\n<p>3) Understand the pathophysiology of placental abnormalities in monochorionic twin pregnancies<\/p>\n<p>What happens after fertilization? see figure 1<\/p>\n<p>Formation of zygote (diploid cell with 46 chromosomes) in fallopian tube, day 0 \uf0e0 cleavage to form blastomeres (cells produced by division) \uf0e0 blastomeres divide to form a solid ball of cells known as the morula, day 3-4 \uf0e0 accumulation of fluid between morula cells to form a blastocyst, day 4-5 (58-cell stage: 5 cells = inner cell mass, 53 outer cells = trophoblast that surrounds the ICM and the blastocele<\/p>\n<p>What is \u201chatching\u201d? When does the blastocyst implant?<\/p>\n<p>The blastocyst is released from the zona pellucidum via secretion of proteases from the endometrium \uf0e0 allows association of trophoblasts with endometrium for implantation at day 6-7<\/p>\n<p>How do twins develop? Figure 1<\/p>\n<p>1) 80% &#8211; Two separate ova fertilized \uf0e0 dizygotic \uf0e0 dichorionic, diamniotic<\/p>\n<p>2) 20% &#8211; Single fertilization followed by splitting of the zygote \uf0e0 monozygotic \uf0e0 variable in chorionicity &#038; # of amnion; 1\/250 pregnancies &#8211; independent of race, heredity, age, parity<\/p>\n<p>What determines the # of chorions and amnions in monozygotic twins? Figure 2 &#038; 3<\/p>\n<p>The timing of division<\/p>\n<p>0-3 days (~33%)\u2013 di-di; before morula stage &#038; differentiation of trophoblast<\/p>\n<p>4-8 days (~67%)\u2013 mo-di; after differentiation of trophoblast, before the formation of the amnion<\/p>\n<p>8-12 days (~1%)\u2013 mo-mo<\/p>\n<p>&gt;13 days \u2013 conjoined twins \u2013 mo-mo<\/p>\n<p>What are common complications with multiples?<\/p>\n<p>-Spontaneous abortion, congenital anomalies, hypertensive disorders, preterm delivery<\/p>\n<p>-Growth restriction: Monochorionic: 1)Unequal allocation of blastomeres 2)vascular anastomoses in the placenta\uf0e0unequal distribution of nutrients\/oxygen; Dichorionic: unequal placentation\uf0e01 placental site receives more perfusion<\/p>\n<p>What are unique complications of monozygotic pregnancies?<\/p>\n<p>-Monoamniotic twins: high fetal death rate, estimated at 17%, &gt;50% from cord entanglement<\/p>\n<p>-Monochorionic twins: sharing fetal circulations through anastomoses of placental arteries &#038; veins (A-A, V-V, A-V); Deep A-V communications create a \u201cthird circulation deep\u201d within villous tissue; if significant pressure \uf0e0shunt develops \uf0e0chronic fetofetal transfusion<\/p>\n<p>TTTS: Unidirectional flow through AV anastomoses \u2013 deoxygenated blood from donor placental artery pumped into a cotyledon shared by the recipient \uf0e0imbalance of blood volumes; Donor becomes anemic, growth restricted, oliguric with oligohydramnios (\u2193renal perfusion); recipient becomes polycythemic &#038; circulatory overload (hydrops)<\/p>\n<p>Treatment: laser ablation of anastomoses is preferred for severe TTTS, amnioreduction, selective feticide, septostomy (intentional creation of communication between dividing amniotic membrane) Multiple Gestation Pregnancies<\/p>\n<p>Liang A<\/p>\n<p>Figure 1 Figure 2<\/p>\n<p>Figure 3<\/p>\n<p>Cunningham F, Leveno KJ, Bloom SL, Spong CY, Dashe JS, Hoffman BL, Casey BM, Sheffield JS. &#8220;Chapter 5. Implantation and Placental Development.&#8221; Williams Obstetrics, Twenty-Fourth Edition. New York, NY: McGraw-Hill; 2013.<\/p>\n<p>Cunningham F, Leveno KJ, Bloom SL, Spong CY, Dashe JS, Hoffman BL, Casey BM, Sheffield JS. \u201cChapter 45. Multifetal Pregnancy.\u201d Williams Obstetrics, Twenty-Fourth Edition. New York, NY: McGraw-Hill; 2013.<\/p>\n<p>Kibble JD, Halsey CR. \u201cChapter 9. Reproductive Physiology.\u201d Medical Physiology: The Big Picture. New York, NY: McGraw-Hill; 2014.<\/p>\n<p><\/div>\n","protected":false},"excerpt":{"rendered":"<p>Duration 10:10<\/p>\n","protected":false},"author":2,"featured_media":0,"parent":160,"menu_order":9,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-386","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/brooksidepress.org\/basic_obgyn\/wp-json\/wp\/v2\/pages\/386","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/brooksidepress.org\/basic_obgyn\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/brooksidepress.org\/basic_obgyn\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/brooksidepress.org\/basic_obgyn\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/brooksidepress.org\/basic_obgyn\/wp-json\/wp\/v2\/comments?post=386"}],"version-history":[{"count":2,"href":"https:\/\/brooksidepress.org\/basic_obgyn\/wp-json\/wp\/v2\/pages\/386\/revisions"}],"predecessor-version":[{"id":475,"href":"https:\/\/brooksidepress.org\/basic_obgyn\/wp-json\/wp\/v2\/pages\/386\/revisions\/475"}],"up":[{"embeddable":true,"href":"https:\/\/brooksidepress.org\/basic_obgyn\/wp-json\/wp\/v2\/pages\/160"}],"wp:attachment":[{"href":"https:\/\/brooksidepress.org\/basic_obgyn\/wp-json\/wp\/v2\/media?parent=386"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}