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PubMed2000

Anticipating twin-twin transfusion syndrome in monochorionic twin pregnancy. Is there a role for nuchal translucency and ductus venosus blood flow evaluation at 11-14 weeks?

Twin-twin transfusion syndrome is a major complication of monochorionic twin pregnancies. In foetuses from monochorionic twinning the presence of increased nuchal translucency thickness (NT) has been associated with an increased risk of developing this syndrome. One of the presumed mechanisms of increased NT is early cardiac failure, indirectly indicated by abnormal blood flow in the ductus venosus. We present eleven cases of monochorionic twin pregnancies in which nuchal translucency thickness and ductus venosus blood flow evaluation was performed at 11-14 weeks. In the two cases presenting with nuchal translucency discrepancy between the two foetuses along with anomalous ductus venosus blood flow in the foetus with increased nuchal translucency, twin-twin transfusion syndrome (TTTS) eventually developed. In none of the twins displaying no inter-twin difference in NT measurements and in those with discrepant NT but normal flow in both ductus venosus, was the progression to TTTS observed. In the two cases which developed TTTS, foetoscopic laser coagulation of the vascular anastomosis was successfully carried out at 18 weeks and normalisation of the venous return was registered. These findings suggest that the association of increased NT and abnormal flow in the ductus venosus in monochorionic twins may be an early manifestation of haemodynamic imbalance between the donor and the recipient eventually manifested as twin-twin transfusion syndrome. Further studies, however, are necessary to establish the potential role of the combination of NT and ductus venosus blood flow assessment as a screening method for TTTS.

Adult↗

PubMed1996

Agenesis of the ductus venosus in a case of monochorionic twins which mimics twin-twin transfusion syndrome.

We describe a pair of monochorionic twins with clinical manifestation of twin-twin transfusion syndrome, including discordant fetal growth, hydrops of the larger twin, and the 'stuck twin' phenomenon of the smaller twin. In the hydropic twin, we found agenesis of the ductus venosus and an abnormal umbilical vein draining directly into the inferior vena cava. There was also marked enlargement of the right atrium, representing the volume overload on it. We believe that the agenesis of the ductus venosus in the larger twin may have contributed to the 'unbalanced shunting' between the monochorionic twins. This then led to a clinical picture mimicking that seen in the authentic twin-twin transfusion syndrome.

Adult↗

PubMed2006

Leptin and bone turnover in monochorionic twins complicated by twin-twin transfusion syndrome.

INTRODUCTION: To test the hypothesis that the bone metabolism of a growth-restricted foetus is regulated by genetic, placental and/or foetal factors through leptin, we investigated the foetal bone turnover in monochorionic pregnancies complicated with or without twin-twin transfusion syndrome (TTTS). METHODS: Maternal and cord bloods were collected from gestational-age-matched monochorionic twins with (n=15) and without (n=15) TTTS. The samples were assayed for leptin, cross-linked carboxyl terminal telo-peptide (ICTP, a marker of bone resorption) and pro-peptide (PICP, a marker of bone formation) of type I collagen by radioimmunoassay (RIA). RESULTS: In the growth-restricted donor twin, the plasma concentration of leptin (P < 0.001), PICP (P < 0.001) was lower, while that of ICTP (P < 0.001) was higher than the recipient twin of the TTTS group. In contrast, leptin, PICP and ICTP were comparable in non-TTTS twins. In the recipient twin of TTTS and non-TTTS twins, leptin was positively associated with PICP (r=0.73; n=45, P < 0.001) and negatively with ICTP (r=-0.68; n=45; P < 0.001). No such association was found between leptin and bone marker in the growth-restricted donor twin of the TTTS group. CONCLUSION: Our data suggest that, in AGA twins, leptin maintains bone metabolism by inhibiting resorption and enhancing bone formation. In contrast, growth-restricted donor twins have high bone turnover and this does not seem to be due to leptin deficiency.

Adolescent↗

PubMed2001

Acquired right ventricular outflow tract obstruction in the recipient twin in twin-twin transfusion syndrome.

OBJECTIVES: The goal of this study was to determine the prevalence and evolution of acquired right ventricular outflow tract obstruction (RVOTO) in the recipient twin in twin-twin transfusion syndrome (TTTS). BACKGROUND: Twin-twin transfusion syndrome complicates 4% to 26% of diamniotic monochorionic twin gestations and is associated with high fetal morbidity and mortality. Cardiac dysfunction and biventricular hypertrophy may develop in the recipient twin with the potential for RVOTO. METHODS: This was a retrospective review of a two-center experience of TTTS to describe the prevalence and evolution of acquired RVOTO in the recipient twin. Right ventricular outflow tract obstruction was diagnosed or excluded by fetal or postnatal echocardiography or clinical assessment. RESULTS: Of 73 twin pregnancies with TTTS identified between 1994 to 1998, a total of seven (9.6%) were complicated by RVOTO in the recipient twin: two subvalvar/muscular, four valvar and one combined. Of 44 pregnancies with fetal echo, six had in utero RVOTO with antegrade flow diagnosed at gestational ages ranging from 19 to 27 weeks. In utero progression occurred in four cases over a period of four to eight weeks, with the development of RVOT atresia by delivery. Postnatal progression of RVOTO occurred in two cases, one of which required pulmonary balloon valvuloplasty at age two years. Postnatal regression of subvalvar RVOTO occurred in two cases in early infancy. Death related directly or indirectly to the RVOTO occurred in all four patients who developed complete RVOT obliteration. CONCLUSIONS: Right ventricular outflow tract obstruction may occur in the recipient twin of at least 9% of pregnancies complicated by TTTS. Right ventricular outflow tract obstruction progression is common in utero and may worsen neonatal outcome.

Canada↗

PubMed1995

Extrauterine twin-twin transfusion syndrome after birth in conjoined twins.

Cross-circulation of conjoined twins in utero has been demonstrated and the extent of its severity has varied. Significant 'extrauterine' twin-twin transfusion syndrome after birth, however, caused by an unbalanced shunting within the circulation has not been reported. In a case of omphalopagus conjoined twins complicated by hypovolemia in one twin and hypervolemia in the other, we demonstrated by color Doppler imaging an aberrant vessel from the hepatic artery of one twin to the hepatic vein of the other. Unbalanced shunting through this aberrant vessel was suspected and urgent separation of the conjoined twins was undertaken. Circulatory changes after birth leading to 'extrauterine twin-twin transfusion syndrome' are discussed. A possible explanation of the pathophysiology of intrauterine twin-twin transfusion syndrome is also given.

Adult↗

PubMed2001

Discordant fetal leptin levels in monochorionic twins with chronic midtrimester twin-twin transfusion syndrome.

The objective of this study was to determine the plasma leptin concentrations in monochorionic twin fetuses with and without twin-twin transfusion syndrome (TTTS). Paired maternal and fetal blood samples were obtained at birth from monochorionic twin pregnancies complicated with (n=12) or without TTTS (n=12). Amniotic fluid samples were also collected from twin pairs at amnioreduction and/or fetal blood sampling in utero. Plasma and amniotic fluid leptin concentrations were measured by radio-immunoassay. Fetal leptin levels in the growth-restricted donor were lower than the recipient twin of the TTTS group (Delta mean 3.7; CI 2.6 to 4.7 ng/ml; P< 0.001). Fetal leptin levels were comparable between non-TTTS twin pairs (Delta mean 0.9; CI 0.1 to 1.4 ng/ml; P=0.10) and recipient twins of TTTS (P=NS). Maternal plasma concentrations of leptin were comparable between the two groups and were higher than the fetal levels. There was a positive association between cord leptin levels and birthweight of twin pairs (y=0.002x-0.37; r=0.58; P< 0.01; n=48). A significant positive relation was also found between delta leptin levels and percentage discordance in birthweight in the TTTS group (y=0.25x-2.21; r=0.82; P< 0.001, n=12). In conclusion, leptin levels in the recipient twins were three times higher than their growth restricted donor twins. However further studies are warranted to elucidate the underlying mechanism.

Amniotic Fluid↗

PubMed1990

[Significance of twin to twin transfusion syndrome in the prognosis of twin pregnancies and its prenatal diagnosis by ultrasonography].

The reason why TTS worsen the prognosis of twin pregnancies was discussed with reference to case results for perinatal death, and antenatal diagnostic criteria for TTS by ultrasonography was established. Of 12 perinatal deaths in 71 twin pregnancies, eight fetuses were affected with TTS (1 acardia, 4 donors, 3 recipients). Perinatal mortality rate (39.3%), rate of preterm lobar (62.2%), rate of polyhydramnion (50.0%), mean amniotic fluid volume (3.310 ml) and cord cross section area ratio (2.38) in monochorionic discordant twins were higher than in the other three groups (monochorionic concordant twins, dichorionic discordant twins and dichorionic concordant twins). Eight fetuses among 12 monochorionic discordant twins were affected with TTS. All twins which showed a single GS in early pregnancy were monochorionic twins. Therefore TTS was considered to have a poorer prognosis than usually reported for all TTS, and to find monochorionic discordant twins with a high cord cross section area ratio must be the key in the screening of TTS. Antenatal diagnosis of TTS by ultrasonography is summarized as follows: 1) A single GS in early pregnancy. 2) Estimated body weight difference between the twins/estimated body weight of the larger twins greater than or equal to 0.2. 3) Cord cross sectional area ratio greater than or equal to 2.0.

Adult↗

PubMed2004

Zygosity diagnosis in young twins by questionnaire for twins' mothers and twins' self-reports.

The present study deals with the determination of zygosity in twins of childhood age by simple questionnaire. The subjects were 224 twin pairs and their mothers, consisting of 159 monozygotic and 65 same-sex dizygotic pairs, identified by genetic markers including DNA samples. Mothers of twins responded to 19 questionnaire items dealing with twin similarity in 16 items about physical features and 3 items about the degree of similarity and frequency of being mistaken (confusion of identity) when twins were about 1 year of age. The twins themselves responded to three questionnaire items dealing with only confusion of identity items. The results of stepwise logistic regression analysis were as follows: the total accuracy of the mothers' questionnaire was 91.5% when using only the items dealing with confusion of identity. This accuracy was slightly lower than that obtained by twins' self-reports dealing with nearly the same question items of confusion of identity, answered by both twins separately with 93.3% accuracy. The total accuracy of mothers' questionnaire responses rose to 95.1% when we used all 19 items. In addition to "the frequency of being mistaken", two physical features, namely "shape of fingers" and "shape of eyebrow", were very informative. In conclusion, twin zygosity can be estimated by the use of the mothers' simple questionnaire with sufficient accuracy even in very young twins about 1 year of age.

Female↗

PubMed2006

Perinatal outcome in monochorionic twin pregnancies complicated by amniotic fluid discordance without severe twin-twin transfusion syndrome.

OBJECTIVES: To assess the natural history and perinatal outcome in monochorionic diamniotic twin pregnancies with discordant amniotic fluid volume without signs of severe twin-twin transfusion syndrome (TTTS). METHODS: This was an observational study of 84 consecutive monochorionic twin pregnancies which did not meet the criteria for severe TTTS and endoscopic laser coagulation of placental anastomoses at initial presentation. The population was subdivided into two groups. Group 1 consisted of 64 pregnancies (median gestational age, 20.1 (range, 15.6-24.7) weeks) with amniotic fluid discordance and no signs of congestive heart failure in the twin with the larger amniotic fluid volume (Twin 1) and positive end-diastolic flow in the umbilical artery of the twin with the smaller amniotic fluid volume (Twin 2). Group 2 (median gestational age, 19.1 (range, 16.0-24.4) weeks) consisted of 20 pregnancies with amniotic fluid discordance and intrauterine growth restriction (IUGR) (abdominal circumference < 5th percentile) in combination with absent or reversed end-diastolic (ARED) flow in the umbilical artery of Twin 2. After exclusion of one patient from Group 1, who opted for termination of pregnancy, nine patients in Group 1 and one in Group 2 developed severe TTTS, and laser coagulation was offered. The remaining 54 pregnancies of Group 1 were compared with the remaining 19 pregnancies of Group 2. RESULTS: Fetuses in Group 1 showed significantly higher survival rates (overall survival, 100/108 (92.6%) vs. 23/38 (60%), P < 0.0001; survival of both fetuses, 49/54 (90.7%) vs. 9/19 (47.4%), P = 0.0002) and median gestational age at delivery (33.6, (range, 27.6-37.8) weeks vs. 32.0 (range, 26.9-36.3) weeks, P = 0.0457). Overall, there was a significantly higher incidence of complications, defined as necessity for intrauterine intervention, fetal or neonatal death or delivery prior to 32 weeks, in Group 2 (Group 1: 30/63 (47.6%); Group 2: 16/20 (80%), P = 0.0188). CONCLUSIONS: Our data suggest that amniotic fluid discordance in monochorionic diamniotic twin pregnancies in combination with IUGR and umbilical artery ARED flow in one fetus represents an extremely high-risk constellation for adverse pregnancy outcome.

Adult↗

PubMed1993

Twin-to-twin transfusion syndrome: a subset of the twin oligohydramnios-polyhydramnios sequence.

OBJECTIVE: Our purpose was to assess the adequacy of currently accepted criteria for the diagnosis of twin-to-twin transfusion syndrome. STUDY DESIGN: Between April 1991 and February 1992 nine consecutive women with twin gestations and ultrasonographic findings of marked growth discordance, coexistent oligohydramnios-polyhydramnios, monochorionic placenta, and same sex of the fetus in the second trimester were evaluated. Mean gestational age at diagnosis was 19 weeks 5 days +/- 5 weeks, and mean growth discordance was 34% +/- 9%. Seven women underwent attempted sequential amniocentesis and cordocentesis at 23 weeks 6 days +/- 2 weeks 4 days to obtain amniotic fluid and cord blood from each fetus. Type O negative, leucocyte-poor, washed adult red blood cells were transfused into the small, oligohydramnic twin during cordocentesis; immediately afterward blood from the polyhydramnic twin was tested with the Kleihauer-Betke stain. RESULTS: The combined procedure was successful in six (86%) of the cases attempted. True twin-to-twin transfusion was confirmed in only four (44%) of those initially identified by ultrasonographic criteria. Hemoglobin difference > 5 g/dl was present in only one of the four cases, and in this case the recipient was anemic. CONCLUSIONS: Currently accepted criteria are insufficient for the diagnosis of true twin-to-twin transfusion. Ultrasonographic findings of marked growth discordance, coexistent oligohydramnios-polyhydramnios, monochorionic placenta, and same sex identify the twin oligohydramnios-polyhydramnios sequence.

Amniocentesis↗

PubMed2001

Controlled fetal blood-letting of the recipient twin as a new method for the treatment of severe twin-twin transfusion syndrome: preliminary results.

OBJECTIVE: To investigate the feasibility of withdrawal of blood from the recipient twin as a new method for the treatment of severe twin-twin transfusion syndrome. METHODS: Seven consecutive monozygotic monochorionic twin pregnancies affected by severe twin-twin transfusion syndrome were treated. Fetal blood was withdrawn from the recipient twin using cordocentesis. The volume of blood to be removed was determined using the formula for intrauterine blood transfusion of anemic fetuses. Fetal outcome was evaluated in relation to changes in the amniotic fluid and in growth curves (comparing the differences between the centiles of the estimated fetal weight before the procedure and the centiles of weight at birth), fetal mortality, gestational age at delivery, neonatal weight and neurological damage. RESULTS: Overall, seven of the 14 (50%) fetuses survived; at least one fetus survived in five (71%) pregnancies, both fetuses survived in two (29%) pregnancies, while in two (29%) pregnancies there were no survivors. No maternal complications were observed. At follow-up, one (14%) baby had minor neurological damage. CONCLUSIONS: Withdrawal of blood from the recipient twin in the treatment of severe twin-twin transfusion syndrome was associated with survival similar to that of the alternative techniques of serial amniodrainage and fetoscopic laser surgery, with some possible advantages such as reduced neurological damage compared with serial amniodrainage. It is also less invasive compared with fetoscopic laser surgery.

Cordocentesis↗

PubMed1994

Clinical and echographic features of in utero cardiac dysfunction in the recipient twin in twin-twin transfusion syndrome.

OBJECTIVE: Fetal twin-twin transfusion syndrome (TTTS) presenting in the second trimester has been associated with almost no perinatal survival until recently, when serial drainage of amniotic fluid has improved the prognosis to 70%-80%. Most recipient twins now survive but develop cardiac dysfunction. The study was undertaken to evaluate the abnormal echocardiographic features and clinical complications of cardiac disease in the recipient twin of TTTS. DESIGN: Antenatal and postnatal echocardiographic and clinical observational study. SETTING: Antenatal studies in a tertiary referral centre. Postnatal management and follow up were performed by the same paediatric cardiologist, either at the obstetric hospital or at the regional referral centre. PATIENTS: Twin pregnancies complicated by TTTS with severe polyhydramnios diagnosed earlier than 25 weeks that proceeded until viability (n = 5). INTERVENTION: Serial fetal echocardiography with colour Doppler. Postnatal echocardiography in the first week and between two and seven months. Serial amnioreduction was performed in all pregnancies. Digoxin treatment, pericardiocentesis, paracentesis, or laser ablation of placental anastomoses was undertaken when there was hydrops. RESULTS: Increased cardiothoracic ratio and tricuspid regurgitation were seen in all recipient twins. High pulmonary artery velocities developed in three. One recipient twin died a week after delivery of endocardial fibroelastosis and infundibular pulmonary stenosis. Two other had balloon dilatation for pulmonary stenosis, one shortly after birth and one at four months. A further twin has apical thickening of the right ventricle at six months. The remaining recipient twin had normal echocardiographic findings at follow up. CONCLUSION: This report characterises for the first time a cardiac disease acquired in utero in the recipient twin in pregnancies complicated by TTTS. Clinical manifestations in utero range from mild to critical pulmonary stenosis or lethal cardiomyopathy. Although perinatal prognosis seems to be related to the severity of dysfunction when first diagnosed in utero, follow up in infancy is recommended in view of the possibility of progressive pulmonary stenosis.

Echocardiography, Doppler↗

PubMed1998

Twins, placentas, and genetics: acardiac twinning in a dichorionic, diamniotic, monozygotic twin gestation.

We describe a human acardiac twin with associated vascular anastomoses in a dichorionic diamniotic fused twin placenta. A 22-year-old woman delivered a healthy 3,554 g male infant and a fused diamniotic dichorionic twin placenta with a 230 g umbilical cord-attached, skin-covered, ovoid mass, consistent with acardiac amorphus. By gross and histological examination, the placental dividing membranes comprised four leaves, one amnion from each placenta, and two centrally fused chorions, diagnostic of dichorionicity. Placental barium injection of the normal twin's umbilical vein showed an anastomosis with the acardiac twin which traversed the dividing membranes, then supplied major vessels of the acardiac mass via its 5.5 cm umbilical cord. DNA-typing studies of the normal twin's placenta and of the acardiac twin's tissues revealed identical alleles at 11 distinct genetic polymorphic loci, consistent with monozygosity. Our findings demonstrate that vascular anastomoses can occur in dichorionic twin placentas, and that human acardiac twinning is not, as heretofore believed, restricted to monochorionic placentas.

Abnormalities, Severe Teratoid↗

PubMed2003

Monoamniotic-versus diamniotic-monochorionic twin placentas: anastomoses and twin-twin transfusion syndrome.

OBJECTIVE: The purpose of this study was to compare monoamniotic-monochorionic and diamniotic-monochorionic twin placentas and to estimate the incidence of twin-twin transfusion syndrome in monoamniotic-monochorionic twin pregnancies. STUDY DESIGN: We analyzed the angioarchitecture and cord insertion distance in 24 monoamniotic-monochorionic and 200 diamniotic-monochorionic placentas. RESULTS: Compared with diamniotic-monochorionic placentas, monoamniotic-monochorionic placentas had significantly more arterioarterial anastomoses (20/20 vs 159/200, respectively; P=.013), significantly less opposite arteriovenous anastomoses (10/20 vs 165/200, respectively; P=.002), similar venovenous anastomoses (6/20 vs 46/200, respectively; P=.323), and arteriovenous anastomoses (20/20 vs 187/200 respectively; P=.279) and significantly shorter umbilical cord distances (median [+/-SD], 5.0+/-6.9 cm vs 17.5+/-6.8 cm; P<.001). CONCLUSION: Monoamniotic-monochorionic and diamniotic-monochorionic placentas have different anastomotic patterns. The (virtually) 100% incidence of arterioarterial anastomoses in monoamniotic-monochorionic placentas explains the reason that twin-twin transfusion syndrome rarely occurs in monoamniotic-monochorionic twin pregnancies and predicts that twin-twin transfusion syndrome manifestations are approximately 5 times less often recognized in monoamniotic-monochorionic pregnancies than in diamniotic-monochorionic pregnancies.

Amnion↗

PubMed1998

Extrauterine twin-twin transfusion affects renal function and perioperative management of conjoined twins.

This series describes the occurrence of unbalanced circulatory shunting in three consecutively treated pairs of conjoined twins. The impact of renal functional changes and compensatory cardiac physiology on the timing of surgery and perioperative management are illustrated. The craniopagus set of twins presented in renal failure (1A) and cardiac failure (1B) to our hospital at age 2.5 years. Renal transplantation for anuria was performed in 1A before separation of the twins. This did not improve urine output in the hypoperfused twin, and normal renal function was not restored until the twins were separated. Two sets of omphalopagus twins were delivered and transferred to our hospital and separated during the first week of life. In each case a preoperative oliguric state in the underperfused twin reversed after separation, and a postoliguric diuresis ensued. Serum creatinine levels were similar in each pair preoperatively despite the inequality in urine volumes. In conjoined twins, assessment of renal function is necessary and should include serial measurements of urine volumes and urine creatinine clearance. Serum creatinine is not a useful marker of individual twin renal function in this situation. When disparity in renal function exists, early separation is indicated to prevent renal failure and compensatory cardiac failure.

Child, Preschool↗

PubMed2004

Modelling the influence of amnionicity on the severity of twin-twin transfusion syndrome in monochorionic twin pregnancies.

Clinical treatment for diamniotic-monochorionic twin-twin transfusion syndrome (TTTS) may include conversion of diamniotic pregnancies to a monoamniotic-monochorionic state by disrupting the amnion septum. We sought to test the underlying hypothesis, i.e. that a monoamniotic state reduces the severity of TTTS. With use of our previously developed mathematical model of two equal fetoplacental circulatory units connected by various sizes and types of placental anastomoses, we compared the haemodynamic and amniotic fluid dynamics of monoamniotic and diamniotic twins that develop TTTS. We used three anastomotic patterns that produce severe, moderate or mild forms of TTTS, respectively, in our diamniotic-monochorionic twin model. Monoamnionicity was modelled by adding the two amniotic fluid volumes and using the volume-averaged amniotic fluid osmolality. The results were as follows: for severe TTTS, small differences develop between diamniotic and monoamniotic donor twins in fetal urine production, swallowed volume, blood volume, blood pressures, net fetofetal transfusion, and blood and amniotic fluid osmolality. However, the circulatory imbalance between the monoamniotic twins deteriorates similar to that of diamniotic twins. The pathophysiological differences tend to disappear for milder TTTS. In conclusion, our model suggests that the uncommon finding of TTTS in monoamniotic twins is not due to the presence of a single amniotic sac. Rather, clinically significant differences in anastomotic patterns and the delayed or lack of identification of manifestations in monoamniotic twins account for the reduced rate of TTTS diagnosis. Based on these results we expect the clinical disruption of the amnion septum in diamniotic-monochorionic TTTS pregnancies to have only minimal benefits.

Amnion↗

PubMedDate not supplied

Changes in survival of twins delivered after twin-twin transfusion syndrome versus preterm singletons over the calendar years 1970-1994.

OBJECTIVE: The use of serial amniotic fluid volume reduction for the treatment of twin-twin transfusion syndrome (TTTS) became available about 1986 and may account for a recent increase in survival of TTTS twins. To determine whether the increase in survival has been due to advances in neonatal care rather than the advent of amnioreduction, the current study evaluated whether increases in survival of preterm TTTS twins were greater than increases in survival of preterm singletons from studies before 1986 compared to studies after 1986. METHODS: Medline literature search identified all reported cases of TTTS and all reports of severely preterm neonatal survival. Studies were divided into groups according to gestational age at birth (</=27 vs. >27 weeks) and midyear of each study (</=1986 vs. >1986). Comparison was performed of the increase in survival from pre-1986 studies to post-1986 studies between preterm singletons and TTTS twins. RESULTS: When comparing studies from before 1986 to after 1986, there was no difference in the increase in survival between preterm (>27 weeks) TTTS twins (67-92%) and preterm (>27 weeks) singletons (79-91%) (p = NS). When comparing studies from before 1986 to after 1986, there was a greater increase in survival among severely preterm (</=27 weeks) TTTS twins (0-22%) than among severely preterm (</=27 weeks) singletons (47-57%) (p = 0.036). CONCLUSIONS: Because of the paucity of data on TTTS twins and the retrospective nature of this study, conclusions are limited. There appears to be some basis for the belief that amnioreduction improves survival in TTTS twins delivered at </=27 weeks' gestation. These results confirm the need for a randomized, controlled trial of expectant management versus amnioreduction for the treatment of TTTS.

Amniotic Fluid↗

PubMed1998

Placental pathophysiology of the twin oligohydramnios-polyhydramnios sequence and the twin-twin transfusion syndrome.

Currently accepted sonographic criteria for antenatal diagnosis of twin-twin transfusion (TTT) syndrome include a monochorionic placenta with same-sex twins, marked growth discordance, and oligohydramnios of the growth-retarded twin with coexistent polyhydramnios of the larger twin. Our previous report of nine women fulfilling these criteria, examined using sequential funipuncture of both fetuses, demonstrated inter-twin blood transfusion in only four cases (44 per cent). It was proposed that traditional sonographic criteria actually describe a heterogeneous group of disorders more appropriately described as the twin oligohydramnios-polydramnios sequence (TOPS). True TTT is a subset of this population, the antenatal diagnosis of which requires specific demonstration of transfusion from one fetus (donor) to the other (recipient). In this report, antenatal placental evaluation has been correlated using duplex pulsed-wave Doppler analysis of arterial blood flow velocity with postpartum gross and histopathologic evaluation of the placenta, with special attention to microvasculature. There was a higher incidence of resistance to blood flow, abnormal umbilical cord insertion, and diminished placental microvasculature associated with oligohydramnic growth-retarded (donor) twins when compared with polyhydramnic (recipient) twins. Based on these observations, it is proposed that TTT and TOPS represent asymmetric placental insufficiency resulting from aberrant placentation.

Blood Flow Velocity↗