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57 Cards in this Set
- Front
- Back
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btw asians, blacks, and whites, put them in order from most likely to have twins to least likely?
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blacks
white asians |
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what factors cause an increase in the probability of becoming pregnant?
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increase w/ maternal age
increased w/ parity positve family hx multiovulatory drugs -monozygotic is independant of these factors ad occurs 1/2500 pregnancies |
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what is one way to determine if twins are mono, dizogotic
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sex them
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explain the membranes and their probablility w/ dizogotic and monozigotic twins?
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Dizigotic=2 eggs, 4 membranes(DC/DA)=70%
Monozygotic: DC/DA-10% MC/DA 20% MC/MA-3%-splits 8-13 days after fertilization |
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explain the days the egg splits(from fertilization), and what becomes as a result of this?
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4 days-DC/DA
4-8days-MC/DA 8-13 days-MC/MA >13days=conjoined twins |
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explain discordinant growth of twins
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1) 1 or both don't demonstrate any growth or increse in size over a 2 wk period
2) 1 or both have an EFV<10th percentile 3)>20 % discrpency of the EFW based on the wight of the larger twin |
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explain the growth rate of twins?
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-similar to singletons until 28-30 wks
->30 wks; grow slower than singletons -term=38 wks -IUGR occurs in 30% of a twin |
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fetal papyraceuous
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mumified fetus(die in utero)
-calcified fetus w/ onligo around it |
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lambda sign
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aka twin peak sign(indicates DC/DA)
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why do most cord knots occur?
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due to MC/MA pregnancies(50%)
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what is the prognosis of conjoined twins?
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-40% still born
-35% die within 24 hours -surgical separation dependant on shared organs -c-section |
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what type of membranes do TTTS and TRAP have?
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MC/DA
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what type of membranes do conjoined and parasitic twins have?
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MC/MA
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when is the optimum time to determine chorionicity?
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10-14 wks
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T/F TTTS cant' happen w/ MC/MA twinning?
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true
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What are the complications of the recipeint and the donor w/ TTTS?
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recipient:
-hypervolemia -poly -CHF -hydrops -crdiac dysfunction -polycythemia-too many red cells Donor: -hypovolemia -oligo(anuric) -stuck(contractures) -growth restricted -pulm. hypoplansia -anemic |
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what are some other names for TTTS?
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-fetal parabiotic syndrome
-twin oligio poly sequence(TOPS) |
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Name the stages of TTTS from least severe to most based on the sonographic appeance?
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1=donor bladder visible
2=donor blad not visible; recipient has bladder=intervension 3=abnormal doppler=desprite intervension 4=hydrops 5=demise of 1 twin |
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what are options for treatment of twin/oligo poly sequency? explain?
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-amnioreduction
-amnioseptostomy(cut through the amnion to balence out fluid) -laser ablation-laser fiber inserted through an endoscope into the uterus to block all vessels that AV fuse. |
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fetus infetu?
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embedding of fetus due to viteline duct anastamosis
-incusion of parasitic twin within its partner differential=teratoma |
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multifetal pregnancy reduction
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-offerend to patients w/ higher order multiple pregnancies in an attempt to reuce both fetal and maternal perinatal mortality
-offered @ 10-12 wks -assoc. w/ additional 10% loss rate -potassium chloride injection -done in DC pregnancies only |
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supine hypotensive syndrome
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increased nasea and dizziness when laying flat on back due to pressure of baby compressing the IVC
-have patient lay on her left side |
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what are the maternal risks w/ twins? fetal risks?
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-preeclampsia
-3rd trimester bleeding -prolapse cord Fetal: -umbilival cord prolapse -premature delivery -congenital anomolies |
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how often do conjoined twins occur?
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1/50,000-100,000
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explain conjoined twins?
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arise from MC/MA gestation where division occurs >13th day resulting in incomplete cleavage of the embryo
-always the same sex -femal 70% of the time -"pagus"-greek word for fastening -single umbilical cord w/ abnormal # of vessels(supranumery) |
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name and explain how conjoined twins are classified?
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-thoracopagus(joined @ thorax-40%)
-omphalopagus(joined @ abdominal wall-34%) -craniopagus-joined @ head -pyopagus-joined@ buttocks(18%) -ishiopagus-joined @ ishia -xiphopagus-joined at xiphoid |
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what is the most common type of conjoined twins?
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-thoracomphalopagus
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what are the sonographic findings w/ conjoined twins?
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-1st tri-V or shaped pole
-no separating membrane in twin gestation -inability to separate bodies -most are fused ventrally and face eachother resulting in backwards flexion of cervical spine ->3 vessels in a single umbilical cord -polyhydramnios(50%) |
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what are some complex fetal anomolies seen w/ conjoined twins?
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-unusial extension of the spine
-single heart -proximity of extremities -polyhydramnios(50%) |
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explain twin embolization syndrome?
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-demise of a co-twin in MA pregnancies can result in embolization of clot and debris across the placental anastamosis to the surviving twin
-it is now thought of to be due to changing pressured btw 2 twins instead of emboilization -selective termination not performed in MC twinning due to risk of TES for the surviving twin -w/ DC/DA pregnancies, demise of 1 twin is only a minimal risk for the surviving twin - |
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when a co-twin dies and is embedded in membranes, what is this called? explain it
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fetal papyraceous:
-rare -when a DC/DA or MC/DA 2nd trimester cotwin demise occurs, the water content and soft tissue of the dead fetus may be resorbed. -results in a small, flattend fetus w/ little or no fluid surrounding it |
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parasitic twinning
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-one twin is within the abdomin of its sibling
-fetus in fetu-complex fibrous mass containing some fluid and a fetus suspended by a cod -complex mass within the fetus -benign -may be confused w/ teratoma |
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what does trap syndrome stand for?
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twin reversed arterial perfusion
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explain trap syndrome
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-occuse in monochorionic pregnancy where there is a placental arterial-arterial and venous-venous anastamosis btw twins
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explain the acardiac twin in trap syndrome?
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-blood received from donor twin is not well oxygenated and enterns the acardiac twin through the umbilical artery.
-reversed perfusion results in development of lower extremities, but sacrificed upper thorax, head and upper extremities |
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how does TRAP syndrome impact the pump twin?
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pump twin=normal twin
-effects the heart -increased cardiac output, and blood flow to the kidneys leads to overproduction of fetal urine -this can lead to preterm labour and premature delivery |
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what is the outcome for the pump twin in TRAP syndome?
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50% survive
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what is the management for trap syndorme
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-termination or interruption of flow to acardiac fets by surgical extraction, fetoscopic umbilical cord ligation, radiofrequency ablation, emboliziton, and or laser vaporization
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heterotopic twinning
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-occurs 1/60000
-single or multiple untrauterine pregnancies w/ an ectopic pregancy |
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what are some predisposing conditions fro heterotopic twinning?
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-oculation induction
-PID -tubal surgery -endometriosis -IVF |
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superfetation
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-2 separate ova fertilized months apart
-ovulation occurs after conception |
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superfecundation
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2 ova fertilized by 2 different sperm within the same ovulation cycle
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what does TTTS stand for?
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twn-twin transfusion sydrome
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how often does TTTS occur
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15-20% of monozygotic twins
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explain TTTS
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-occurs in monochorionic twins only
-cannot occur w/ dichorionic pregnencies even if the placentas fuse -arterial blood of one twin is pumped into venous blood of the other -donor twin is small -recipient twin is normal or macrosomic -both twins risk dying -70-80% mortality -dead fetus sometimes develops into fetal papyraceus -if there is no intervension, there is a 30% chance that 1 twin will survive |
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explain the donor twin in TTTS?
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-becomes small, anemic, and hypotensive
-oligo develops due to decreased perfusion of kidneys -decreased urine output -starving to death |
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explain the recipient twin in TTTS?
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-gets too much blood flow
-normal or macrosomic -poly due to excess blood through kidneys, and increased urine output -at risk for heart faulure and may be hydropic |
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explain stuck twin
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-occurs w/ oligo in one sac and poly in the other(diamniotic)
-donor twin w/ oligo may be held in a fixed position by the membrane -any cause of oligo can result in this appearance, not just TTTS |
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vanishing twin
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-1st trimester loss
-resorption of one twin -occurs in 20% of 1st trimester twins |
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what is the sonographic appearance of vanishing twins?
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-small or empty often irregular sac along a normal fetal gestation
or... -nonviable twin appearing as a fetal papyraceus along uterine wall or.. early vanishing twin distinguished from implantation bleed by the presence of a trophoblastic ring or... w/ DC/DA-normal growth of one embryo, and elimination of the other. |
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how do you sonographically distinguish btw a vanishing twing and an implantation bleed?
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vanishing twin will have a trophoblastic ring
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what are the maternal complications associated w/ multiple gestations?
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-premature labor(most common complication); due to uterine overdistension resulting in contractions
-PROM due to increased intramniotic pressure -HTN -Anemia -pyelonephritis -hepatic cholestasis -preeclamsia -eclamsia |
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what are the fetal complications associated w/ multiple gestations?
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-prematurity
-IUGR -congenital anomolies(@ twice the rate) |
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what is considered discordinant growth
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-500gm or 20% weight diff. btw. twins
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what is the most common genetic defect in MZ twinning?
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normal fetus w/ a turner's syndome twin
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T/F dizigotic twins have a high chance of genetc and developmental abrnomalities?
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false-low chance compared to monozygotic
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how do genetic defects effect monozygotic twins?
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-almost 100% concordant in monozygotic twinning
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