Discordant nuchal translucency in monochorionic twin pregnancy. A case report

The twin-to-twin transfusion syndrome is a serious anomaly occurring from vessels anastomosis between the fetal-planetary circulations of monochorionic twin pregnancies with a high perinatal morbidity and mortality. In the first trimester, the presence of discordant increase of the nuchal translucency associated a reverse blood flow in the ductus venosus are marks of twin-to-twin transfusion syndrome. In this report, we related a case of monochorionic twin pregnancy in the first trimester in that the first diagnostic signal this syndrome was an increase of the measurement of nuchal translucency, associated the reverse blood flow in the ductus venosus of receiving fetus.     

Twin pregnancy

Twins account for 2–3% of all births. They carry significant risks to both mothers and babies. These risks include preterm delivery, intrauterine growth restriction and pre-eclampsia. In addition, monochorionic gestations confer an even higher rate of perinatal morbidity and mortality arising from a shared placenta due to placental anastamoses, which may lead to twin-to-twin transfusion syndrome (TTTS). It is essential that chorionicity is established in the first trimester in order to initiate the appropriate antenatal management and surveillance. In view of the high risk of both maternal and fetal complications, twin pregnancies are ideally managed in a dedicated clinic according to agreed protocols.     

Search for hemodynamic compromise at 11-14 weeks in monochorionic twin pregnancy: is abnormal flow in the ductus venosus predictive of twin-twin transfusion syndrome?

BACKGROUND AND OBJECTIVES: Twin-twin transfusion syndrome is a devastating complication of monochorionic twin pregnancies. The presence of increased nuchal translucency thickness (NT) in one of the monochorionic twins has been associated with an increased risk of developing this syndrome. One of the most plausible mechanisms for increased nuchal translucency is heart failure, indirectly manifested by abnormal blood flow in the ductus venosus. We aimed to clarify the pathophysiology of increased NT found more frequently in monochorionic twins prone to develop twin-twin transfusion syndrome. DESIGN: We present 50 cases of monochorionic twin pregnancies in which nuchal translucency thickness was measured and ductus venosus blood flow evaluation was performed at 11-14 weeks of gestation. RESULTS: Whenever the fetuses of a twin pregnancy were found to have discrepant nuchal translucency thickness measurements and abnormal flow in the ductus venosus was found in the fetus with increased nuchal translucency thickness, twin-twin transfusion syndrome eventually developed. Progression to twin-to-twin transfusion syndrome was not observed in the twins displaying no intertwin difference in nuchal translucency thickness measurements and it was not observed in those with discrepant nuchal translucency thickness but normal flow in the ductus venosus of both fetuses. In the two cases which developed twin-to-twin transfusion syndrome, fetoscopic laser coagulation of the vascular anastomoses was successfully carried out at 18 weeks and normalization of the venous return was recorded. CONCLUSIONS: Both increased nuchal translucency and abnormal flow in the ductus venosus in monochorionic twins may be early manifestations of haemodynamic imbalance between donor and recipient. The combined evaluation of both parameters in monochorionic twin pregnancies may constitute an effective method for identifying those at risk of developing twin-to-twin transfusion syndrome.     

Twin pregnancy

Twins account for 2–3% of all births. They carry significant risks to both mothers and babies. These risks include preterm delivery, intrauterine growth restriction, and pre-eclampsia. In addition, monochorionic gestations confer an even higher rate of perinatal morbidity and mortality arising from a shared placenta due to placental anastomoses, which may lead to twin-to-twin transfusion syndrome (TTTS) or twin anaemia-polycythaemia sequence (TAPS). It is essential that chorionicity is established in the first trimester in order to initiate the appropriate antenatal management and surveillance. In view of the high risk of both maternal and fetal complications, twin pregnancies are ideally managed in a dedicated clinic according to agreed protocols with both obstetric and midwifery input.     

The long term neurologic outcome of children from pregnancies complicated by twin-to-twin transfusion syndrome

OBJECTIVE: To assess long term outcomes of children from pregnancies complicated by twin-to-twin transfusion syndrome. DESIGN: Comparison of children from pregnancies with twin-to-twin transfusion syndrome in Western Australia with a contemporaneous regional comparison cohort of preterm and term infants studied using an identical assessment procedure. POPULATION AND SETTING: All infants aged > or =18 months were identified from a geographically based longitudinal cohort of monochorionic twin pregnancies with an antenatal diagnosis of twin-to-twin transfusion syndrome conducted prospectively since 1992. METHODS: Children were evaluated using age-specific developmental and behavioural assessments. Cerebral palsy was diagnosed clinically and ascertainment confirmed through the Western Australian Cerebral Palsy Register. MAIN OUTCOME MEASURES: Intellectual disability, cerebral palsy, behavioural and cognitive function. RESULTS: Fifty-two children were identified as eligible for study and assessments were performed on 49 (94%). Three surviving children had a diagnosis of cerebral palsy (5.8%). The mean IQ score was 8 points lower in twin-to-twin transfusion syndrome children compared with the comparison cohort although this was mainly due to a decrement of 13 points in those born before 33 weeks of gestation. There was no difference between the donor and the recipient twin in terms of IQ scores (median difference -3, 95% CI -9 to 6). There was no relationship of IQ score to the worst stage of the twin-to-twin transfusion syndrome. Child Behavior Check List and Vineland Adaptive Behavior Scale scores did not differ between twin-to-twin transfusion syndrome children and the comparison group. CONCLUSIONS: Twin-to-twin transfusion syndrome is associated with a significant reduction in IQ score in very preterm survivors. There seems to be no increase in the prevalence of cerebral palsy. Overall behaviour and adaptive behaviour scale scores are similar to a comparison group.     

Recipient's vascular doppler pattern immediately following death of the donor in a case of untreated severe twin-to-twin transfusion syndrome

In a stage III twin-to-twin transfusion syndrome, death of the donor at 31 weeks was followed by unusual umbilical artery (UA) doppler findings in the recipient, with a high diastolic peak velocity and a low S/D ratio. Besides, middle cerebral artery waveforms could not be obtained in the recipient. The recipient was delivered by emergency cesarean section, weighed 1,230 g, was strikingly pale and had a cord hemoglobin concentration of 15 g/dl. Neonatal blood average pressure was of 29 mm Hg, immediately after delivery, and ranged from 33 to 43 mm Hg in the first 12 h of life. Neonatal heart function returned to normal on day 2. We hypothesize that death of the donor twin induced an acute decrease in placental resistance. This phenomenon, combined with decreased systolic blood flow due to the recipient's systolic function impairment, could account for the umbilical artery flow pattern we observed. The acute decrease in volemia and the presence of systemic hypertension and cardiomyopathy may explain the inability to obtain middle cerebral artery doppler. This complex hemodynamic disturbance in the recipient may be responsible for morbidity unrelated to anemia in case of donor's demise, as acute fetal distress.     

Prenatal cardiovascular manifestations in the twin-to-twin transfusion syndrome recipients and the impact of therapeutic amnioreduction

OBJECTIVE: We evaluated the cardiovascular pathologic condition in the recipient twin in twin-to-twin transfusion syndrome and the influence of amnioreduction. STUDY DESIGN: Fetal echocardiograms and medical records of 54 pregnancies that were complicated by twin-to-twin transfusion syndrome were reviewed. Recipient twin right and left ventricular wall thickness, diameters, systolic and diastolic function, valve regurgitation, and structural cardiac defects were assessed at examination and after amnioreduction. RESULTS: At examination (n = 28 pregnancies), cardiomegaly because of right ventricular and/or left ventricular hypertrophy was observed in 58% of recipient twins, and biventricular hypertrophy was observed in 33% of recipient twins, without ventricular dilation. Biventricular diastolic dysfunction was present in two thirds of recipient twins, and right ventricular systolic dysfunction and significant atrioventricular valve regurgitation was observed in one third of recipient twins. Serial assessment (n = 21 pregnancies) revealed progressive biventricular hypertrophy and right ventricular systolic and biventricular diastolic dysfunction in most recipient twins. Steeper progression of hypertrophy, diastolic dysfunction, and structural or functional right ventricular outflow disease (20% incidence) were associated with an increased perinatal mortality rate. CONCLUSION: In twin-to-twin transfusion syndrome, the recipient twin has progressive biventricular hypertrophy with predominant right ventricular systolic and biventricular diastolic dysfunction. Despite amnioreduction, the cardiovascular disease persists and even progresses in many recipient twins.     

Strategies of antenatal diagnosis and management of pathologies related to multiple pregnancies

In the first trimester, ultrasound is crucial to screen for aneuploidies based on nuchal translucency, to diagnose major birth defects, and to establish chorionicity. Indeed prenatal diagnosis strategies as well as obstetrical management options are largely based on placental type. In the second trimester, maternal serum screening is not as effective, and ultrasound screening is more difficult in twins than in singletons. When a severe abnormality in found in one twin, selective termination of pregnancy may be considered. This technique is safe in dichorionic twins, but hazardous in monochorionic pregnancies. Selective termination in dichorionic twins is safer in the first trimester, underscoring the need for early prenatal diagnosis in twins. Monochorionic twin pregnancies carry specific risks, such as the twin-to-twin transfusion syndrome, which can be treated by endoscopic photo-coagulation of intertwin anastomoses in the severe early onset cases, or by amnioreduction in milder cases.     

Intervalle de naissance entre les jumeaux : une limite de temps est-elle justifiée ?

OBJECTIVES: To assess the effect of the twin-to-twin delivery interval on the umbilical cord blood gas status and the neonatal outcome of the second twin following vaginal delivery. PATIENTS AND METHODS: Retrospective study of twin deliveries at or beyond 34 weeks of gestation over a period of five years. The correlation between the twin-to-twin delivery interval, and the umbilical arterial blood gas parameters of the second twin, including pH, PO(2), PCO(2), HCO(3-) and base excess, was studied. A second analysis was performed after exclusion of non-vertex presentation, need for general anesthesia, growth restriction and weight difference between the twin>30%. RESULTS: Two hundred and thirty-nine patients were studied. The mean twin-to-twin delivery interval was 11.3+/-6.4 minutes (between 6 and 14 minutes in 56.1% of cases). The second twin had more Apgar score<7 at 1 minute (P<0.02) and more arterial ombilical pH<7.20 (P<0.01) than the first twin. Over 15 minutes, the mean arterial pH was lower (P<0.01) and the number of arterial pH<7.20 increased (P<0.03). In contrast, the mean Apgar score and the rate of neonatal transfer did not differ significantly. There were significant negative correlations between arterial pH, base excess and bicarbonates and the twin-to-twin delivery interval (P<0.05). Similar results were found in the homogenised population. The reduction in the second twin arterial pH was expressed as pH=7.282-0.003 x time. DISCUSSION AND CONCLUSION: Umbilical cord arterial blood gas parameters deteriorate with increasing twin-to-twin delivery interval. Our results suggest that this interval should be less than 15 minutes, but obstetrician should adapt to every clinic situation.     

The acardiac twin. A case report

The acardiac twin is a rare consequence of monozygotic twinning and occurs in 1 per 35,000 deliveries. One percent of all monozygotic twins is affected. Prenatal diagnosis is possible with ultrasonography. Complications associated with the presence of an acardiac twin include sequelae from the twin-to-twin transfusion syndrome, polyhydramnios, dystocia, ruptured uterus and congestive heart failure in the normal twin. In utero fetal therapy is possible in some instances.     

Single fetal demise in twin gestation

A single fetal demise in a twin gestation occurs infrequently: it is recognized in fewer than 7% of twins past the first trimester. Increased morbidity is associated primarily with monozygotic twins who have vascular anastomoses associated with diamniotic-monochorionic placentation, and with monoamniotic twins. Morbidity and mortality of these twin gestations potentially can be reduced with identification of the at-risk pregnancy and with intensive antenatal surveillance. The most difficult management problem is the twin-to-twin transfusion syndrome, which will require improved technologic developments to resolve.     

Acute foeto-foetal transfusion syndrome--case report and review of the literature

The perinatal morbidity and mortality risk in monochorionic twin pregnancies are 3-5-fold increased compared to those of dichorionic twin pregnancies. Partially, this is due to the higher rate of preterm delivery but also to the twin-to-twin transfusion syndrome (TTTS). Caused by unidirectional blood flow via placental anastomoses, the TTTS leads to weight differences of more than 20% between monochorial twins. The blood donor often shows oligohydramnios, whereas the recipient shows polyhydramnios. Lewi et al. demonstrated, in a study with 202 monochorionic twin pregnancies, a 9% rate of severe TTTS. The mortality of this complication is about 90% when untreated. In contrast to the chronic TTTS, little is known about the acute intrapartal one, which is characterised by anaemia and hypovolaemia of the donor and polyglobulia of the recipient without significant weight differences between the two. In most cases, anaemia occurred after normal delivery of the first twin. Still, there are no means or signs for early detection. We describe the case of a 30-year-old primigravida with a monochorionic diamniotic twin pregnancy. During pregnancy, no evidence of TTTS could be detected. At 37 + 1 weeks gestation labour was induced with prostaglandin-containing gel. Both foetuses showed cephalic presentation. The CTG of the first twin showed a conspicuous heart rate. After labour the first twin presented with anaemia and hypovolaemic shock, the APGAR was 2/7/8. The infant's haemoglobin was 13.7 g/dL. After delivery, the second twin with APGAR 10/10/10 showed a haemoglobin of 19.6 g/dL, which is in the upper normal range. Their birth weights differed by merely 10.4%. Acute TTTS is frequently characterised by anaemia and hypovolaemia of the second twin. In our case of a monochorionic twin delivery with acute TTTS the donor was born first. Early diagnosis and neonatal intervention is essential for reducing postnatal morbidity and mortality.     

Brain damage to the survivor within 30 min of co-twin demise in monochorionic twins

Single fetal death in a twin pregnancy in the late second or early third trimester is associated with significant morbidity and mortality rate in the surviving co-twin, especially in monochorionic twin pregnancies. The common causes are twin-to-twin transfusion syndrome, chromosomal abnormalities, and congenital anomalies of the fetus or anomalies of the umbilical cord-placenta. Here we report a case of monochorionic twin pregnancy in which one fetus had a single umbilical artery (SUA) while the co-twin had two umbilical arteries. The twin with SUA died in utero at the 30th week of gestation and the other fetus was delivered by cesarean section immediately due to fetal distress diagnosed by cardiotocography. Disseminated intravascular coagulation and multicystic encephalomalacia have been observed in the surviving neonate. This case and review of the literature suggest that neurologic complication rates are also increased in monochorionic twin pregnancies with single fetal demise despite the immediate delivery as in our case.     

Fetal umbilical artery flow velocity-time waveforms in twin pregnancies

Summary. The umbilical artery flow velocity-time waveforms were studied in 76 twin pregnancies. The ratio of peak systolic (A) to least diastolic (El) velocity was calculated for each fetus as an index of umbilical placental flow resistance. Seventy-one sets of twins were studied within 14 days before delivery. In 65 cases both twins were alive at the time of study. In 32 pregnancies both fetuses were of birthweight appropriate for gestational age (AGA) and had A/B ratios within the normal singleton range. In 33 pregnancies one or both of the liveborn infants were small for gestational age (SGA) and in 78% of these at least one fetus had an elevated A/B ratio. Discordancy in birthweight and A/B ratio was associated with growth retardation. Clinically manifest twin-to-twin transfusions occurred in five of the ten pregnancies resulting in an SGA infant (eight with discordant weight) associated with a normal and concordant A/B ratio. Two twin-to-twin transfusions were associated with perinatal death. The placentas were examined in 61 patients. In 43 dichorionic pairs the A/B ratio was elevated in 12 of the 18 where there was at least one SGA infant. There was a greater incidence of growth retardation in the monochorionic pairs (12 of 18). Only seven of these were identified by an elevated A/B ratio. In 10 of these 18 pairs vascular anastomoses were demonstrated on placental inspection and in a further two there was evidence of twin-to-twin transfusion by haemoglobin discrepancy. Twin pregnancy may result in the birth of a small-for-dates infant because of intrauterine growth retardation or twin-to-twin transfusion. An abnormally elevated A/B ratio identifies growth retardation. In twin-to-twin transfusion the A/B ratio of the two fetuses is similar (crossed circulation) yet difference in size may be seen on ultrasound measurement.     

Twin-to-twin transfusion syndrome: what are appropriate diagnostic criteria?

One hundred seventy-eight consecutive twin pregnancies were studied to reevaluate the standard diagnostic criteria for chronic twin-to-twin transfusion syndrome of an intertwin hemoglobin difference greater than 5 gm/dl and a birth weight difference greater than 20%. Hemoglobin differences greater than 5 gm/dl were found in six pregnancies with monochorionic placentas but also in seven with dichorionic placentas. Birth weight differences greater than 20% occurred no more commonly in monochorionic than in dichorionic pregnancies. Of the four pregnancies with a coexisting hemoglobin difference greater than 5 gm/dl and birth weight difference greater than 20%, only one had a monochorionic placenta and therefore likelihood of vascular anastomoses. Diagnosis of twin-to-twin transfusion syndrome cannot be definitively established by current standard diagnostic criteria.     

Complicated monochorionic twin pregnancies: experience with bipolar cord coagulation

OBJECTIVE: The purpose of the study was to evaluate our experience with ultrasound-guided bipolar diathermy forceps for cord occlusion in complicated monochorionic twin pregnancies. STUDY DESIGN: Seventeen consecutive cases were included: 9 cases were twin-to-twin transfusion syndrome; 2 cases were twin reversed arterial perfusion syndrome, and 6 cases were discordant for fetal abnormality. Bipolar diathermy was performed under local anesthetic with the use of 3-mm forceps with ultrasound guidance. RESULTS: Cord occlusion was successfully accomplished in all cases between 18 and 27 weeks' gestation. There were 2 deaths of the co-twin within 12 hours; 1 death was due to cord hemorrhage, and 1 death was unexplained. One neonatal death occurred after delivery at 27 weeks, and 1 woman with twin-to-twin transfusion syndrome elected termination of pregnancy when hydrocephaly was diagnosed 7 days after the procedure (probably related to the underlying pathologic condition). All other co-twins are alive and well, although 2 pregnancies were complicated by preterm delivery and premature rupture of membranes before 30 weeks' gestation. CONCLUSION: Bipolar diathermy is an effective procedure for cord occlusion, although it still has significant morbidity and mortality rates.     

Umbilical cord cyst in a monochorionic twin pregnancy: an experiment of nature for the treatment of twin-twin transfusion syndrome

A patient with a monochorionic twin pregnancy developed signs of twin-twin transfusion syndrome from 18 weeks of gestational age. At 23 weeks, an umbilical cord cyst and absent diastolic umbilical artery flow were noted in the donor twin. The pregnancy progressed uncomplicated until term and resulted in vaginal delivery of 2 healthy male babies at 38 weeks of gestational age. We hypothesize that the compression on the umbilical arteries of the donor twin by the umbilical cord cyst has resulted in a partial "compensation" of the twin-twin transfusion phenomenon.     

Endoscopic laser coagulation of placental anastomoses in 200 pregnancies with severe mid-trimester twin-to-twin transfusion syndrome

OBJECTIVE: To investigate perinatal outcome after endoscopic laser coagulation of the placental vascular anastomoses in severe mid trimester twin-to-twin transfusion syndrome (TTTS). STUDY DESIGN: In a prospective study between January 1995 and September 1999, we performed laser therapy in 200 consecutive pregnancies with TTTS between 16 and 25 weeks of gestation. We compared outcome of the first group of 73 pregnancies whose outcome has been reported previously in a study comparing laser surgery and serial amniodrainages [Am J Obstet Gynecol 1999;180:717-24], with the following group of 127 patients. RESULTS: The overall survival rate increased from 61% (89/146) in group 1 to 68% (172/254) in group 2. The percentage of pregnancies with survival of both fetuses was 42% (31/73) in group 1 and increased to 54% (69/127) in group 2 (P=0.142). The survival rate for at least one fetus was 81% (103/127) in group 2. The median gestational age at delivery of liveborn babies was 33.7 weeks in group 1 and 34.4 weeks in group 2 with a median interval of 13 weeks between the intervention and delivery. CONCLUSION: This study of a large population of pregnancies with severe second trimester twin-to-twin transfusion syndrome confirms the improvements of outcome after laser therapy as compared to serial amniodrainages reported previously. Furthermore, it shows a trend towards an increase in survival rates with growing experience in this technique, most likely attributable to a more selective identification and efficient coagulation of the placental vascular anastomoses.     

Intratwin arteriovenous fistula of the placenta in a case of twin-to-twin transfusion syndrome

Arteriovenous fistulas of the placenta are extremely rare in singleton pregnancies and, to our knowledge, have not previously been reported in twin gestations. We describe a case of an arteriovenous fistula of the placenta in a diamniotic-monochorionic twin pregnancy complicated by twin-to-twin transfusion syndrome (TTTS). The arteriovenous fistula was demonstrated by color-coded vascular injection studies of the placenta. We speculate that the hemodynamic effects of the fistula may have contributed to the refractoriness of the TTTS to serial amniodrainages and laser ablation of communicating intertwin vessels.