Stage I: The ultrasound shows an imbalance of amniotic fluid around the twins, but the donor twin's bladder is still visible. · Stage II · Stage III · Stage IV ...CareSpecialties&DepartmentsMidwestFetalCareCenterOverviewConditionsandServicesMeettheTeamWhattoExpectOutcomesResearchFAQLocationandContactUsForHealthProfessionalsGivingWhatistwintotwintransfusionsyndrome(TTTS)?Twintotwintransfusionsyndrome(TTTS)isaconditionthatoccursonlyinmonochorionicpregnancies —onesinwhichtwoormoregeneticallyidenticalbabies(usuallytwins)sharethesameplacenta.Althoughallidenticaltwinsshareaplacenta,TTTSdevelopsinabout10to15percentofthosepregnancies.Theconditiondoesnotoccurwhenthetwinsarenon-identical(fraternal).Whenbabiesshareaplacentatheyalsoshareconnectingbloodvessels.Usuallythebloodflowisequallybalancedbetweenthem,andthebabiesareabletogrowanddevelopnormally(Figure1).ButincasesofTTTS,theflowofbloodbecomesunbalanced,andonebabywillactuallydonatebloodtotheother.Whenthishappens,thebabydonatingtheblood(the“donor”twin)becomesdehydratedandstopsmakingurine.Thisresultsinadecreaseinamnioticfluid,theprotectiveliquidthatsurroundsthebabyinthewomb.Thebabyreceivingtheextrablood(the“recipient”twin),however,produceshigher-than-normalamountsofurine,resultinginexcessamnioticfluid(Figure2).Untreated,TTTScanbelife-threateningforbothbabies.Thedonortwinmayexperiencemuchslower-than-normalgrowth,whiletherecipienttwinisatriskofheartfailureduetotheextravolumeofblood.TwintotwintransfusionsyndrometreatmentisavailableatMidwestFetalCareCenter.InsomeTTTScasesonlyredbloodcellstransferbetweenthebabies.Inthesecasestheamnioticfluidlevelsremainnormal.ThisformofTTTSisknownasTwinAnemiaPolycythemiaSequence(TAPS).Itoccurswhenthevascularconnectionsbetweenthebabiesareonlytinybloodvesselsinthesharedplacenta,permittingjustredbloodcellstoflowfromonebabytotheother.Overtime,toomanyredbloodcellsbuildupintherecipienttwin’sblood,causingthebloodtothicken(aconditionknownaspolycythemia).Atthesametime,thedonortwin’sbloodwillhavetoofewredblo