Scheduled maintenance: Saturday, March 6 from 3–4 PM PST
Upgrade to remove ads
Only $2.99/month

Twin-to-twin transfusion syndrome

Terms in this set (14)

Placenta vs. twin placentas
placenta: -developing fetus receives nutrition (through umbilical cord)
-Where umbilical cord meets placenta it branches into many vessels (radiate out and penetrate placenta like roots of tree)
Twin placenta: more than one fetus in uterus must share resources provided by mother
-two main types of twin placentas: 1.dichorionic (each fetus connected to own separate placenta- although there might be competition between fetuses there is no direct sharing of blood bet. twins)
2.monochorionic (two fetuses share one placenta, monochorionic twins always identical twins (usually separated by thin wall (membrane) but have many direct connections to placenta), connections btw. blood vessels that radiate from each cord insertion are called vascular anastomoses (shunts)- allow passage of blood btw. their circulations, anastomoses found in all monochorionic pregnancies, twins exchange blood back and forth (in uncomplicated monochorionic pregnancies equal exchange in both directions -> balance btw. circulations)
-complicated monochorionic twins:

-sharing bet. monochorionic twins is not equal or unbalanced-> can lead to complications (TTTS is such a complication)
http://umm.edu/programs/ttts/health/what-is-ttts

-type of placenta nurturing identical twins plays significant role in development of complications in multiple gestation
-the impetus for and the timing of the embryo to split into identical twins is unknown (the later this occurs the more complications are seen)
-type of placenta determined by when (in days) embryo randomly splits into twins following the fertilization of the egg (conception)
(Twinning within first 4 days ->dichorionic placentas-> these twins have lowest complication rates)
(Twinning four or more days after conception -> monochorionic (MC)placenta
btw. 4-8 days the MC twins will have separate sacs of water (diamnionic) despite a shared placenta, but after 8 days will also be in same sac (monoamnionic)
-Diamnionic monochorionic (4-8 days split) twins are most common placental type for identical twins (most cases of TTTS occur in this group)
-if twins have a MC placenta it is absolut proof that they are "identical"
-MC placenta contains two anatomic variables thought to develop randomly (contribute to and explain why, when and to what degree TTTS will affect twins)
-1. is the presence of blood vessels in placenta (connect the umbilical cords and circulations of the twins)
-2. is the variations in the way the twins share their common placenta
(in some MC twins both these abnormalities may be present)
http://www.tttsfoundation.org/medical_professionals/monochoirionic_placenta.php
TTTS
-may threaten both twins
-unequal exchange of blood, placental sharing of nutrients,fluid, and oxygen
-donor twin sends blood and fluid to placenta but does not get equal amount back from placenta
-recipient twin also sends blood into placenta but gets back an excess of fluid and blood cells
-this met difference leaves donor short of fluid and placental supplies while recipient is overloaded
-occurs mainly b/c of blood vessel connections deep in placenta or on its surface
-artery of one twin may connect with artery of other twin (arterio-arterial anastomosis)
-similarly a vein of one twin can connect with corresponding vein from from the other (veno-venous anastomosis)
-these connections are on surface of placenta and permit blood exchange in both directions
-sometimes arteries coming from one twin to supply an area in placenta (the cotyledon) do not drain into a vein returning to same twin - blood is drained by a vein connections the other twin (such an arteriovenous anastomosis deep in placenta allow blood flow un one direction -> acts like one-way valve)
-if amount of blood flow in one direction can't be balanced by enough blood flow in opposite direction, then an imbalance is set up - if this imbalance progresses further it can lead to TTTS
http://umm.edu/programs/ttts/health/what-is-ttts

-is a disease of placenta (or afterbirth)-affects identical twin pregnancies
-affects identical twins who share common monochorionic placenta
-shared placenta contains abnormal blood vessels (connect umbilical cords and circulations of the twins)
-common placenta may also be shared unequally by the twins (one twin may have a share too small to provide necessary nutrients to grow normally or even survive)
-events in pregnancy that lead to TTTS(timing of twinning event, number/type of connections vessels, and the way the placenta is shared by twins ) are all random events that have no primary prevention and are not hereditary or genetic
-can occur at any time during pregnancy (even while mother is in labor at term)
-placental abnormalities determine when and to what degree a transfusion occurs btw. the twin
http://www.tttsfoundation.org/medical_professionals/what_is_ttts.php

-condition in which identical twins share blood supply due to an anomaly with the blood vessel connections of the placenta (b/c of connection smaller twin acts as donor for larger recipient twin-receives excess fluid resulting in an enlarged bladder ans an in area in amniotic fluid)
- TTTS phenomenon almost exclusive to monochorionic pregnancies
-natural history of severe TTTS well established with mortality rates approaching 80%-100% if left untreated (especially when it presents prior to 20 weeks gestation -> tends to be more severe and more rapidly progressive

http://coloradofetalcarecenter.childrenscolorado.org/conditions/twin-to-twin-transfusion-syndrome-ttts/introduction
Risks general
-if detected in first 20 weeks of pregnancy and left untreated-> very high chance that neither twin will survive
-in TTTS each twin tries to adapt (donor: tries to save water and energy-> donor has low urine output-> low amniotic fluid volume (oligohydramnios) and poor fetal nutrition -> intrauterine growth restriction (IUGR)
recipient: tries to get rid of excess fluid-> increased urination-> excess amniotic fluid (polyhydramnios)
also has to deal with the excess blood cells (put severe stress on the fetal heart ->lead to many complications of increased blood volume and abnormal blood thickness (hyper viscosity)
http://umm.edu/programs/ttts/health/what-are-the-risks
Risks of donor
-as imbalance worsens donor is at risk for abnormalities due to compression (being squashed b/c of low amniotic fluid)
-abnormalities from effects of failing placental function (low oxygen ->brain damage, circulatory collapse, other permanent damages)
-abnormalities from long-term effects of malnutrition
-effects may be made even worse if overstretching of uterus (by excessive amniotic fluid produced by recipient)worsens placental function or if preterm labor starts
-in severe TTTS donor twin very fragile and cannot cope with added stress of prematurity
http://umm.edu/programs/ttts/health/what-are-the-risks

-transfusion causes donor to have decreased blood volume ->slower than normal growth than its co-twin, and poor urinary output
->little to no amniotic fluid or oligohydramnios (the source of most of the amniotic fluid is urine from the baby)
http://www.tttsfoundation.org/medical_professionals/what_is_ttts.php
Risks of recipient
-mainly due to volume overload
-circulatory effect may be thickening of heart muscle-> can progress to heart failure and complications affecting all of the baby's systems
-effects on heart can last into newborn life (may be made much worse if birth is premature)
http://umm.edu/programs/ttts/health/what-are-the-risks

-becomes overloaded with blood
-excess blood puts a strain on baby's heart to the point that it may develop heart failure
-also causes baby to have too much amniotic fluid (polyhydramnios) from a greater than normal production of urine
http://www.tttsfoundation.org/medical_professionals/what_is_ttts.php
Both twins
-circumstances are suboptimal for normal development of either twin ->may account for increased rate of developmental delay observed in monochorionic twins at 2 years of age
-placental anastomoses carry additional danger in event that one twin dies (surviving twin can lose large amount of blood volume across connecting vessels into dead twin-> may cause sudden drop in blood pressure->heart attack/stroke)
-when donor dies the hydramnios disappears quickly (great likelihood that survivor bleeds (backwards through the anastomoses) into donor,partially exsanguinate rapidly and suffer brain damage with subsequent cerebral palsy)
-fate of one twin remains linked to other through placental anastomoses
-if TTTS worsens and recipient creates more and more amniotic fluid it will overstretch the uterus-> may cause mother discomfort and may put pressure on the cervix
-with continuing pressure the cervix may open or membranes may rupture-> miscarriage or preteen delivery (often occurs at an early gestational age where chances of survival are poor9
-even if babies survive dangers of prematurity+ complications from TTTS may lead to permanent injury or even death
http://www.tttsfoundation.org/medical_professionals/history_of_TTTS.php
http://umm.edu/programs/ttts/health/what-are-the-risks
Maternal risks
-physical risks foremother from overdistended uterus, from attempted treatments, and even from delivery
http://umm.edu/programs/ttts/health/what-are-the-risks
Chronic TTTS
-describes cases that appear early in pregnancy (12-26 weeks' gestation)
-these cases are most serious b/c babies are immature and cannot be delivered
-also twins will have a longer time during development in the womb to be affected by TTTS abnormalities
-without treatment most babies would not survive (of the survivors most would have handicaps/ birth defects)
http://www.tttsfoundation.org/medical_professionals/what_is_ttts.php
Acute TTTS
-describes those cases that occur suddenly (whenever there is a major difference in blood pressure btw. the twins
-may occur in labor at term or during last third of pregnancy (whenever one twin becomes gravely ill or even passes away as a result of the abnormalities in shared placenta
-twins may have better chance to survive based on their gestational age (may have greater chance of surviving with handicaps)
http://www.tttsfoundation.org/medical_professionals/what_is_ttts.php
History off TTTS
first delineation of TTTS was by German obstetrician Friedrich Schatz in 1875
Treatment OPTIONS
Fetoscopic Laser Photocoagulation:
-most innovative and completely curative approach has been developed by De Lia (1983)
-confronted the human syndrome by the obliteration of the blood vessel communication on placental surface (required their identification through fetoscopy and then using a laser beam to coagulate the blood within the "third circulation")
-if done successfully the donor urinates immediately -> the hydramnios disappears (avoiding premature delivery) and twins grow more normally
-moreover, possibility of exsanguination by backwards bleeding is forestalled

Source http://www.tttsfoundation.org/medical_professionals/history_of_TTTS.php used:
De Lia, J.E., Kuhlmann, R.S., Cruikshank, D.P., O'Bee, L.R.: Placental surgery: a new frontier. Placenta 14:477-485, 1993

-treatments vary (treatment of TTTS is one of most challenging clinical problems concerning multiple gestations)
-Approx. 20% of all twin pregnancies are monochorionic (incidence of TTTTS in monochorionic diamniotic gestations approx. 5-15 %)
http://coloradofetalcarecenter.childrenscolorado.org/conditions/twin-to-twin-transfusion-syndrome-ttts/introduction

Amnioreduction:
Diagnosis
-lack of agreement on specific diagnostic criteria to define midgestation TTTS+influence of older neonatal criteria have hampered understanding of its pathophysiology and slowed development of more effective treatment strategies
-donor twin characterized by oliguria, oligohydramnios or anhydramnios, growth restriction and abnormal umbilical artery Doppler velocimetry
-recipient characterized by polyuria, polyhydramnios, abnormal venous Doppler, progressive cardiac dysfunction due to TTTS-cardiomyopathy
http://coloradofetalcarecenter.childrenscolorado.org/conditions/twin-to-twin-transfusion-syndrome-ttts/diagnosis
Sonographic Criteria Suggestive of a TTTS
-not all of the following sonographic criteria are necessary for a diagnosis of TTTS, the following findings are suggestive of the diagnosis:
1. Monochorionicity
2.Discrepany in amniotic fluid btw. amniotic sacs with polyhydramnios of one twin (largest vertical pocket greater than 8cm) and oligohydramnios of the other (largest vertical pocket less than 2 cm)
3.Discrepancy in size of umbilical cords
4.Cardiac dysfunction in the polyhydramniotic twin
5.Abnormal umbilical artery or ductus venous Doppler velocimetry
6. Significant growth discordance (often > 20%)
http://coloradofetalcarecenter.childrenscolorado.org/conditions/twin-to-twin-transfusion-syndrome-ttts/diagnosis
Staging for TTTS
Quintero et al. proposed staging system for TTTS (considers a sequence of progressive sonographic features
Stage1:
polyhydramnios in the recipient, severe oligohydramnios in donor but urine visible within the bladder of the donor
Stage2:
polyhydramnios in the recipient, a stuck donor, urine not visible within the donor's bladder
Stage3:
polyhydramnios and oligohydramnios, as well as critically abnormal Dopplers (at least one of absent or reverse end diastolic flow in the umbilical artery, reverse flow in the ductus venosus or pulsatile umbilical venous flow), with or without urine visualized within the donor's bladder
Stage 4:
presence of ascites or frank hydrops (fluid collection in two or more cavities) in either donor or recipient
Stage 5:
demise of either fetus. This staging system is descriptive but had not been validated as prognostically important
Source used by http://coloradofetalcarecenter.childrenscolorado.org/conditions/twin-to-twin-transfusion-syndrome-ttts/staging:
Quintero RA, Morales WJ, Allen MH et al. Staging of twin-twin transfusion syndrome. J Perinatol 1999;19: 550-5.
-large study showed that Quintero stage at presentation, at first treatment and at worst stage did predict both prenatal and double survival but not survival of any twin
Tan TYT, Taylor MJO, Lee LY et al. Doppler for artery-artery anastomosis and stage-independentsurvival in twin-twin transfusion. Obstet Gyneco12004; 103: 1174-80.
-Duncombe et. al. also showed correlation of Quintero stage at initial presentation and perinatal survival

Duncombe GJ, Dickinson JE, Evans SF. Perinatal characteristics and outcomes of pregnancies complicated by twin-twin transfusion syndrome. Obstet Gynecol 2003; 101: 1190-6.
- Quintero staging system provides useful shorthand to describe progression of TTTA along a spectrum of severity
-Yet it has potential limitations in its use in guiding therapy
THIS SET IS OFTEN IN FOLDERS WITH...