Perinatal morbidity and mortality rates in severe twin-twin transfusion syndrome: results of the International Amnioreduction Registry

Incidence, mechanisms, and patterns of fetal cerebral lesions in twin-to-twin transfusion syndrome

OBJECTIVE

To determine the incidence of fetal cerebral lesions and their characteristics in twin-to-twin transfusion syndrome (TTTS).

DESIGN AND SETTING

This was a retrospective analysis at a single center for the period 1999 to 2004 in which 299 cases of severe TTTS at 15-28 weeks of gestation were reviewed.

METHODS

Only cerebral injuries diagnosed during pregnancy or ischemic lesions diagnosed within the first week of life were considered in order to exclude those related to prematurity. We only included cases resulting in at least one survivor at one week after delivery, as well as fetuses that were terminated because of severe cerebral abnormalities. We excluded all fetuses delivered at <24 weeks of gestation that died prior to undergoing postnatal cranial ultrasonography. The main outcome measures were fetal cerebral lesions, intrauterine death, survival, and neonatal death.

RESULTS

Two hundred and ninety-nine pregnancies were evaluated. Three hundred and fifteen fetuses were reviewed. Cerebral abnormalities developed antenatally in 26/315 fetuses (8.25%). All lesions but one were diagnosed prenatally. Prenatal diagnosis of these lesions was achieved primarily by ultrasound (US) and magnetic resonance imaging (MRI), in 20/25 (80%) and in 5/25 (20%) fetuses, respectively. Cerebral abnormalities developed following primary laser coagulation in 12/222 (5.40%), following serial amnioreduction in 9/66 (13.63%), and following expectant management in 3/14 (21.4%) fetuses. Abnormalities developed after single intrauterine fetal death (IUFD) in 14 cases.

CONCLUSIONS

Cerebral morbidity in TTTS mainly occurs following vascular disruptive lesions. Both donors and recipients are at risk of developing either ischemic or hemorrhagic lesions. The risk of developing cerebral lesions in single survivors is significantly lower following laser treatment. Combined use of a targeted US and fetal MRI could detect most cerebral abnormalities antenatally. Timing of the triggering event is critical for planning serial US and MRI follow-up examinations.

A case of successful selective abortion using radio-frequency ablation in twin pregnancy suffering from severe twin to twin transfusion syndrome

Twin to twin transfusion syndrome (TTTS) is one of the major complication of monochorionic twin pregnancy which is mainly understood by placental vascular anastomosis. Perinatal mortality and morbidity is high as 80-100% if untreated and even higher if the disease is developed at early stage. Variety of methods of isolating or intercepting placental vascular anastomosis are introduced, but they are only available in centers where all the required equipments are prepared. We report here a case of TTTS complicated with severe polyhydroamnios during the second trimester. The blood supply to donor twin was interrupted successfully at 19(+2) weeks of gestation by minimally invasive radio-frequency cord ablation, under ultrasound guidance. The normal recipient twin was delivered successfully at 35 weeks of gestation and had no eventful neonatal course.

Twin-to-twin transfusion syndrome: a comprehensive update

Twin-to-twin transfusion syndrome (TTTS) is a serious complication in about 10% to 20% of monozygous twin gestations with an incidence of 4% to 35% in the United States. Severe TTTS is reported to occur in 5.5% to 17.5% of cases. TTTS is a progressive disease in which sudden deteriorations in clinical status can occur, leading to death of a co-twin. Up to 30% of survivors may have abnormal neurodevelopment as a result of the combination of profound antenatal insult and the complications of severe prematurity. This article presents an overview of what is known about the pathophysiology and the diagnosis of TTTS, the role of echocardiography in TTTS, treatment options available for TTTS, complications of treatment for TTTS, and short- and long-term outcomes of TTTS.

Survival after laser surgery for twin-to-twin transfusion syndrome: when are they out of the woods?

PURPOSE

Severe, progressive twin-to-twin transfusion syndrome (TTTS) is associated with near-100% mortality if left untreated. Endoscopic laser ablation of placental vessels (ELA) is associated with 75% to 80% survival of at least one twin. The actuarial risk of fetal demise after ELA has not yet been described.

STUDY DESIGN

A retrospective cohort study from 2 centers on a consecutive series of 163 sets of monochorionic twins with severe TTTS (18 Quintero stage I, 55 stage II, 71 stage III, 19 stage IV) who underwent ELA. Actuarial survival was calculated and stratified for donor vs recipient and according to stage.

RESULTS

Median gestational age at diagnosis was 20.1 weeks; median operative time was 60 minutes. Overall survival was 63%, and survival of at least one twin was seen in 76% of pregnancies. Of fetal demises, 10% occurred within 48 hours after ELA, and 90% of all fetal demises occurred within 1 month. There was a 10% survival advantage of recipients over donors. Survival was similar for stages I, II, and IV (75%-80%), compared with 55% for stage III.

CONCLUSIONS

Actuarial survival curves for TTTS confirms a greater burden on donor than on recipient but not at a previously reported 2:1 ratio. The current staging system does not accurately reflect post-ELA mortality risk. The unexpected higher mortality in stage III may reflect a more acute progression of the disorder in this group, an adverse effect of LA on an as yet unknown subgroup with stage III or, alternatively, preoperative demise of fulminant stage IV patients, leaving a stage IV subgroup with a more benign course and better outcome.

Fetal Doppler: umbilical artery, middle cerebral artery, and venous system

One of the most important applications of Doppler ultrasonography in obstetrics is the detection of fetal anemia in pregnancies complicated by either red-cell alloimmunization or by other causes of fetal anemia. Doppler of the umbilical artery also has prognostic value in pregnancies affected by twin-twin transfusion syndrome undergoing in-utero intervention. Another potential major application is the use of Doppler ultrasound in the management of intrauterine-growth-restricted fetuses. At the present time, there is no single test that appears superior to the other available tests for timing the delivery of the growth-restricted fetus. Therefore, the decision to deliver a fetus, especially at <32 weeks, remains mostly based on empirical management. Doppler may provide a more reliable and systematic basis for timing these deliveries. This review emphasizes the three following concepts: (a) normal and abnormal Doppler of the umbilical artery, middle cerebral artery, mitral and tricuspid valves, umbilical vein, and ductus venosus; (b) some clinical applications of Doppler sonography in obstetrics; and (c) potential future research of Doppler in obstetrics.

Laser coagulation of placental anastomoses with a 30 degrees fetoscope in severe mid-trimester twin-twin transfusion syndrome with anterior placenta

OBJECTIVE

To assess outcome after fetoscopic laser coagulation (FLC) of placental vascular anastomoses with the 30 degrees fetoscope in mid-trimester severe twin-to-twin transfusion syndrome (TTTS) with completely anterior placenta compared with the regular 0 degrees fetoscope in TTTS with other placental locations.

METHODS

This was a prospective study of 176 consecutive monochorionic twin pregnancies undergoing FLC for severe TTTS. Of these, 51 patients required use of the 30 degrees fetoscope (study group) and 125 placental locations permitted use of the 0 degrees fetoscope (controls).

RESULTS

The two groups had very similar outcomes. The median gestational age at FLC in the study group vs. control group was 21.0 (range, 17.4-24.6) weeks vs. 20.6 (range, 15.9-24.6) weeks. Both fetuses survived in 58.8% (30/51) of study patients vs. 66.4% (83/125) of controls. At least one fetus survived in 84.3% (43/51) of study patients and 88.8% (111/125) of controls (P = 0.45). Study patients delivered at a median of 34.1 (range, 25.0-38.4) weeks and controls at 34.0 (range, 25.0-40.3) weeks' gestation.

CONCLUSIONS

Use of a 30 degrees fetoscope for FLC in cases of technically challenging extensive anterior placentation is associated with an outcome that is very similar to that achieved when a 0 degrees fetoscope is used in cases of more favorable placental location.

Endoscopic laser surgery in severe second-trimester twin-twin transfusion syndrome: a three-year experience from a Latin American center

OBJECTIVE

In order to assess the outcome of pregnancies complicated by severe second trimester twin-twin transfusion syndrome (TTTS) undergoing treatment with endoscopic laser surgery, we reviewed our experience following the implementation of an institutional fetal surgery program.

METHODS

Patients presenting with monochorionic-diamniotic twin pregnancies complicated by severe TTTS before 26 weeks of gestation were offered endoscopic laser surgery to coagulate placental vascular anastomoses. Using regional anesthesia and guided by real-time sonography, anastomoses were identified and selectively coagulated. At the end of the procedure, amniodrainage was performed to restore normal amniotic fluid volume. Follow-up and delivery were carried out at the referring institutions. Six-month follow-up was performed in all cases.

RESULTS

During a 3-year period from September 2003 to December 2006, 33 consecutive cases of severe TTTS were operated on at a median gestational age of 21 weeks (range 17-25). Nine (27.3%) cases were classified as stage II, 21 (63.6%) as stage III, and three (9.1%) as stage IV. The placenta was anterior or predominantly anterior in 15 (45.5%) of the cases. Overall, both twins were born alive in 16 (48.5%) cases, only one twin was born alive in 11 (33.3%), and neither was born alive in the remaining six (18.2%). Therefore, 81.8% (27 of 33) of the pregnancies resulted in at least one liveborn infant. Among them, the mean gestational age at delivery was 32 weeks (range 23-38) and the mean birthweight of the liveborn infants was 1591 g (range 350-3800). Thirty-four infants survived the perinatal period, yielding an overall perinatal survival rate of 51.5%, with 75.8% (25 of 33) of the pregnancies resulting in at least one perinatal survivor. All neonatal deaths were associated with extreme prematurity.

CONCLUSIONS

This preliminary experience suggests that selective laser coagulation appears to be a good treatment option in cases of monochorionic twin pregnancies complicated by severe TTTS. However, technical skills and adequate equipment are required for implementing a fetal surgery program. Auditing outcomes during the learning curve would help in identifying potential problems.

A definition of selectivity in laser coagulation of chorionic plate anastomoses in twin-to-twin transfusion syndrome and its relationship to perinatal outcome

OBJECTIVE

This study was undertaken to correlate selectivity of surgery and perinatal outcome in twin-to-twin transfusion syndrome treated by endoscopic laser coagulation, using a quantitative definition of selectivity.

STUDY DESIGN

287 consecutive cases of severe twin-to-twin transfusion syndrome were reviewed. A selectivity index was built as the ratio of selective over nonselective coagulations per procedure. Outcome measures were survival at 28 days and failure of surgery as defined by recurrence of twin-to-twin transfusion syndrome or fetofetal hemorrhage.

RESULTS

Two populations were identified: a high selectivity group (63.8%) and a low selectivity group (36.2%). Survival of at least one twin and survival of both twins were higher in the high-selectivity group (p = .007 and p = .04 respectively). Failure of surgery rates were similar in both groups.

CONCLUSION

A quantitative definition of selectivity appears justified by the large variations found in the practice of a single center and by significant differences in outcome. Survival is significantly improved in highly selective procedures.

Stage I twin-twin transfusion syndrome: rates of progression and regression in relation to outcome

OBJECTIVES

Twin-twin transfusion syndrome (TTTS) results in high rates of perinatal mortality and neurological morbidity. Fetoscopic laser ablation of placental anastomoses is now established as the treatment of choice for advanced disease. However, there remains controversy about its use in early-stage TTTS, in which laser-related fetal losses need to be balanced against relatively favorable outcomes with more conservative approaches. We investigated rates of progression and regression in Stage I TTTS and determined factors influencing the course of the disease.

METHODS

We undertook a retrospective observational study of all TTTS cases referred to our tertiary referral fetal medicine service from 2000 to 2006. In patients presenting with Stage I TTTS, the following variables were evaluated for their ability to predict the course and progression of the disease: gestational age (GA) at presentation, amniotic fluid index, recipient and donor deepest vertical pool, presence of artery-artery anastomoses, small-sized bladder compared to normal donor bladder and fetal size discordance. Study end-points were disease regression or progression, and neonatal survival at 28 days.

RESULTS

Among 132 consecutive cases of TTTS, 46 women presented with Stage I disease. In the majority (69.6%), disease remained stable (28.3%) or regressed (41.3%). Of cases that progressed, 79% did so within 2 weeks and 93% progressed to at least Stage III. No factor was significantly linked with progression or regression, although there was a trend towards the absence of an artery-artery anastomosis (P = 0.10) and the presence of a small rather than normal donor bladder (P = 0.10) influencing progression, and later GA at presentation (P = 0.07) influencing regression. At least one infant survived in 83% of cases and there was double survival in 59%. Perinatal outcome was significantly better in cases that regressed (the rates of at least one survivor and double survival being 89% and 89%, respectively) or remained Stage I (77% and 61%, respectively), compared with those cases that progressed (79% and 14%, respectively). Treatment with amnioreduction at first presentation did not influence progression or regression.

CONCLUSIONS

This study demonstrates that a high percentage of Stage I TTTS cases regress or remain early stage. Identification of factors predicting progression would facilitate the selection of patients for definitive therapy, while avoiding treatment-related morbidities in mild or transient disease.

A prospective, randomized, multicenter trial of amnioreduction vs selective fetoscopic laser photocoagulation for the treatment of severe twin-twin transfusion syndrome

OBJECTIVE

The objective of the study was to examine the effect of selective fetoscopic laser photocoagulation (SFLP) vs serial amnioreduction (AR) on perinatal mortality in severe twin-twin transfusion syndrome (TTTS).

STUDY DESIGN

This was a 5 year multicenter, prospective, randomized controlled trial. The primary outcome variable was 30 day postnatal survival of donors and recipients.

RESULTS

There was no statistically significant difference in 30-day postnatal survival between SFLP or AR treatment for donors at 55% (11 of 20) vs 55% (11 of 20) (P = 1.0, odds ratio [OR] 1, 95% confidence interval [CI] 0.242 to 4.14) or recipients at 30% (6 of 20) vs 45% (9 of 20) (P = .51, OR 1.88, 95% CI 0.44 to 8.64). There was no difference in 30 day survival of 1 or both twins on a per-pregnancy basis between AR at 75% (15 of 20) and SFLP at 65% (13 of 20) (P = .73, OR 1.62, 95% CI 0.34 to 8.09). Overall survival (newborns divided by the number of fetuses treated) was not statistically significant for AR at 60% (24 of 40) vs SFLP 45% (18 of 40) (P = .18, OR 2.01, 95% CI 0.76 to 5.44). There was a statistically significant increase in fetal recipient mortality in the SFLP arm at 70% (14 of 20) vs the AR arm at 35% (7 of 20) (P = .25, OR 5.31, 95% CI 1.19 to 27.6). This was offset by increased recipient neonatal mortality of 30% (6 of 20) in the AR arm. Echocardiographic abnormality in recipient twin Cardiovascular Profile Score is the most significant predictor of recipient mortality (P = .055, OR 3.025/point) by logistic regression analysis.

CONCLUSION

The outcome of the trial did not conclusively determine whether AR or SFLP is a superior treatment modality. TTTS cardiomyopathy appears to be an important factor in recipient survival in TTTS.

Percent absent end-diastolic velocity in the umbilical artery waveform as a predictor of intrauterine fetal demise of the donor twin after selective laser photocoagulation of communicating vessels in twin-twin transfusion syndrome

OBJECTIVE

Absent end-diastolic velocity (AEDV) in the umbilical artery of the donor twin is a known risk factor for intrauterine fetal demise (IUFD) of this fetus after selective laser photocoagulation of communicating vessels (SLPCV) for twin-twin transfusion syndrome (TTTS). The aim of this study was to assess the proportion of time, expressed as a percentage, of the cardiac cycle spent in AEDV (%AEDV) as a predictor of IUFD of the donor.

METHODS

All patients referred for possible SLPCV underwent complete preoperative staging evaluation including Doppler assessment of the umbilical artery. %AEDV was calculated retrospectively as 100 x (time of the cycle spent in AEDV divided by duration of total cardiac cycle). Patients without AEDV were considered to have a %AEDV of 0. Follow-up Doppler studies were performed 16-24 h after SLPCV. IUFD of the donor was recorded if the donor twin died any time prior to delivery.

RESULTS

Of 401 patients undergoing SLPCV, 127 had AEDV. Preoperative AEDV of the donor twin was associated with an increased risk of IUFD of the donor (40.9% vs. 14.2%, P < 0.0001). %AEDV was measured in 72/127 (56.7%) donors with AEDV for whom digital images were available. Within these 72 patients, the mean %AEDV was significantly higher in patients with IUFD of the donor (36.5% vs. 29.6%, P = 0.01). IUFD of the donor was similar in patients with AEDV, regardless of whether %AEDV was measured (36% vs. 47%, P = 0.2). A %AEDV > 30 was associated with a 4.3-fold increase in the risk of IUFD of the donor (95% CI, 1.4-12.7), a sensitivity of 77% and a negative predictive value of 81.3%. Logistic regression showed that %AEDV, but not number of anastomoses, placental location, presence of artery-to-artery anastomoses or the presence or absence of EDV was associated significantly with IUFD of the donor.

CONCLUSION

%AEDV is a novel Doppler parameter in the assessment of patients with TTTS. %AEDV, rather than AEDV alone, is a significant risk factor for IUFD of the donor twin and %AEDV > 30 is associated with an increased risk of IUFD of the donor in TTTS patients treated with SLPCV. Assessment of %AEDV should be considered part of the preoperative evaluation of TTTS patients.

Twin-to-twin transfusion syndrome: Is the future getting brighter?

The twin-to-twin transfusion syndrome (TTTS) continues to pose a major challenge in the area of fetal therapy. Untreated, the mortality and morbidity are extremely high, and the fact that there are two structurally normal fetuses at risk makes the case for effective in utero therapy even more compelling. Advances in therapeutic procedures, in particular the development of selective laser photocoagulation of intertwin vascular anastomoses, have improved outcomes, both in terms of survival and survival free of disability. This review examines the pathophysiology, diagnosis, surveillance, contemporary therapies, expected outcomes and ongoing challenges in TTTS.

Long-term neurodevelopmental outcome in twin-to-twin transfusion syndrome treated with fetoscopic laser surgery

OBJECTIVE

This study was undertaken to determine the long-term neurodevelopmental outcome in twin-to-twin transfusion syndrome treated with laser.

STUDY DESIGN

All twin-to-twin transfusion syndrome cases treated at our center with laser between August 2000 and December 2003 were included in the study. Neurologic, mental, and psychomotor development at 2 years of age corrected for prematurity was assessed in all twin-to-twin transfusion syndrome survivors. Neurodevelopmental impairment was defined as any of the following: cerebral palsy, deafness, blindness, mental, or psychomotor development index of the Bayley Scales of Infant Development II less than 2 SD.

RESULTS

A total of 82 twin-to-twin transfusion syndrome pregnancies were treated with fetoscopic laser surgery during the study period. Perinatal survival was 70% (115/164). The incidence of neurodevelopmental impairment was 17% (19/115) and was due to cerebral palsy (n = 8), mental developmental delay (n = 9), psychomotor developmental delay (n = 12), and deafness (n = 1).

CONCLUSION

The incidence of neurodevelopmental impairment in twin-to-twin transfusion syndrome survivors treated with laser is high and warrants long-term follow-up.

Septostomy with amniodrainage in the treatment of twin-to-twin transfusion syndrome: a 16-case report

OBJECTIVE

To report the treatment results of 16 monochorionic and diamniotic gestations cases, which had complications due to the twin-to-twin transfusion syndrome (TTTS), the neonatal and other possible complications of the septostomy associated to the amniodrainage.

METHOD

Based on ultrasonographic findings, 16 pregnant women were diagnosed with the twin-to-twin transfusion syndrome (TTTS). These cases were divided in two groups: one of them included the fetuses without hydrops and the second included the "recipient" fetuses with hydrops. The therapy measures included septostomy with or without amniodrainage. The following parameters were evaluated: gestational age at the time the septostomy was performed, volume of drained amniotic fluid, gestational age at delivery, birth weight, postnatal evolution, and procedure complications.

RESULTS

The average gestational age for this procedure was of 23.6 weeks (from 14 weeks and 1 day to 33 weeks). The gestational age for the septostomy until the delivery was of 8.18 weeks (from 1.0 to 21.3 weeks). The survival rate in the group without hydrops was of 68.7%, while in the second group it was of 25%. Some of the complications were as follows: two cases of premature membrane rupture and one case of preterm labor.

CONCLUSION

Septostomy with amniodrainage, when performed on the initial stages and on earlier gestational ages has good perinatal results.

Stage-dependent fetal umbilical blood flow changes induced by laser therapy and amniodrainage in twin-to-twin transfusion syndrome

OBJECTIVE

To estimate changes in umbilical blood flow (UBF) and Doppler indices in pregnancies complicated by twin-to-twin transfusion syndrome (TTS) treated with either laser therapy or amniodrainage, and to evaluate the influence of the presence of hemodynamic deterioration prior to therapy, as determined by the Quintero stages of severity.

METHODS

Forty-eight cases of TTS were included, and further classified into severity Stages I or II (absence of critically abnormal Dopplers (CAD), n = 22) and Stages III or IV (presence of CAD or hydrops fetalis, n = 26). In Stages I-II, 14 cases were treated with laser and eight with amniodrainage, and in Stages III-IV, 17 were treated with laser and nine with amniodrainage. Differences in the UBF, umbilical artery pulstility index (UA-PI) and ductus venosus pulsatility index (DV-PI) were estimated for both groups of severity before and after both treatments. Eleven normal monochorionic pregnancies were evaluated as controls.

RESULTS

In recipients, UBF was significantly higher with respect to controls regardless of the stage, while donors had a significant decrease in UBF, but only in Stages III-IV. After laser treatment no changes were observed in fetuses in Stages I-II. In Stages III-IV, recipients showed a significant reduction in the DV-PI (mean DV-PI 1.31 +/- 0.18 vs. 1.05 +/- 0.22; P = 0.005) whereas donors showed a significant increase in the UBF (mean UBF 134 +/- 36 mL/min vs. 195 +/- 25 mL/min; P < 0.001) and in the DV-PI (mean DV-PI 0.99 +/- 0.26 vs. 1.36 +/- 0.42; P = 0.002), and a reduction in the UA-PI (mean UA-PI 1.86 +/- 0.41 vs. 1.58 +/- 0.30; P = 0.01). After amniodrainage only donor fetuses in Stages III-IV showed an increase in UA-PI (mean UA-PI 1.54 +/- 0.35 vs. 1.72 +/- 0.40; P = 0.015). No other changes were observed in any of the parameters studied.

CONCLUSION

Laser therapy induces consistent hemodynamic variations in TTS mainly manifested in Stages III-IV.

The role of laser surgery in dissecting the etiology of absent or reverse end-diastolic velocity in the umbilical artery of the donor twin in twin-twin transfusion syndrome

OBJECTIVE

This study was undertaken to gain insight on the cause of absent or reverse end-diastolic velocity (AREDV) in the umbilical artery (UA) of the donor twin by analysis of individual placental mass and vascular anastomoses in patients with twin-twin transfusion syndrome (TTTS) treated with laser.

STUDY DESIGN

TTTS patients who successfully underwent selective laser photocoagulation of communicating vessels (SLPCV), 16 and 26 weeks' gestation, with both twins born alive and complete Doppler and placental data were considered eligible for the study. Doppler examination of the UA was performed before and 24 hours after SLPCV. Abnormal UA Doppler findings were defined as persistent AREDV. Pre- and post-SLPCV UA Doppler results yielded the following 4 groups: (1) normal-normal; (2) normal-abnormal; (3) abnormal-normal; and (4) abnormal-abnormal. The types of vascular anastomoses were categorized during surgery. Individual placental territory (IPT) was defined as individual placental weight divided by total placental weight x 100.

RESULTS

There were 132 cases in group 1 and no patients in group 2. AREDV resolved in 78% (28/36) of patients (group 3) and remained unchanged in 22% (8/36) (group 4). The mean IPT-donor in group 4 was significantly smaller than in group 1 (P = .015). Patients with preoperative AREDV (groups 3 and 4) were more likely to have artery-to-artery anastomoses (P = .002). However, AREDV resolved in 57% (16/28) patients without artery-to-artery anastomoses.

CONCLUSION

Preoperative AREDV may result from a small IPT, placental vascular anastomoses, or both. AREDV resulting from a small IPT may have a similar cause to that of singletons, and may be inferred by lack of postoperative resolution. Resolution of AREDV after SLPCV implies the presence of an adequate IPT and removal of donor hypotension.

The management of multiple pregnancy

The epidemic of multiple pregnancy continues albeit in a different form with twin pregnancies predominating. Determination of chorionicity is the key to management and regular monitoring by ultrasound is a hallmark of quality care. All multiple pregnancies should be offered first trimester screening by nuchal translucency for aneuploidy. MC twins should be scanned at fortnightly intervals to allow complications such as twin-twin transfusion or IUGR to be detected and referral made to a fetal medicine centre. Maternal complications are common and vigilance is required for their detection. Although planned vaginal delivery can often be achieved, mothers must be prepared for the substantial risk of requiring a caesarean section as this currently occurs in the majority.

Hypothesis: The Placental ‘Steal’ Phenomenon – A Possible Hazard of Amnioreduction

The twin-twin transfusion syndrome (TTTS) complicates approximately 15% of monochorionic twin pregnancies. Severe TTTS is associated with poor neonatal outcome and a relatively high rate of neurological abnormalities. Some studies have suggested this outcome to be more severe in cases treated by amnioreduction. In this paper we present a hypothesis that radical amnioreduction performed after 24 weeks of gestation might cause a shift of blood from the fetus into the placenta. This could explain some of the severe neurological outcomes, such as hypoxic ischemic brain damage, seen in these cases.

Fetal echocardiographic findings are not predictive of death in twin-twin transfusion syndrome

OBJECTIVE

The purpose of this study was to determine whether fetal echocardiographic findings are predictive of prognosis in recipient fetuses with twin-twin transfusion syndrome (TTTS).

METHODS

A cohort of 30 pregnancies with TTTS between 1990 and 2001 was included. Diagnosis and staging of TTTS were made according to the Quintero system. Fetal echocardiographic findings of cardiomegaly, right ventricular hypertrophy, and tricuspid regurgitation were evaluated for relationship with fetal death. Power analysis revealed an approximately 80% power to detect a 2-fold increased risk of fetal death, with alpha = .05. Logistic regression was used to determine the relationship between echocardiographic findings and death.

RESULTS

Most pregnancies were Quintero stage 1, n = 13 (43%), and ranged in severity to Quintero stage 5, n = 4 (13%). Cardiac findings in the recipient fetus that were assessed for a relationship with death included cardiomegaly at the initial appearance of TTTS or at the most severe evaluation findings, right ventricular hypertrophy at initial appearance or at the most severe evaluation findings, or tricuspid regurgitation at initial appearance or at the most severe evaluation findings. Fetal or neonatal death in the recipient twin was not related to the presence of cardiac findings (odds ratio, 0.77; 95% confidence interval, 0.16-3.74).

CONCLUSIONS

Fetal echocardiographic findings, whether evaluated at initial appearance or over the course of serial evaluations, were not related to fetal or neonatal death in recipient twins with TTTS.

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.

[Twin-twin transfusion syndrome and cardiovascular complications]

INTRODUCTION

Twin-twin transfusion syndrome carries high morbidity and mortality, related in part to the cardiovascular alterations that it produces.

CASE REPORT

Patient 1 underwent a cesarian section at week 28 due to myocardial dysfunction and severe tricuspid regurgitation in the recipient twin. Twelve hours after birth the recipient twin developed refractory shock. Severe biventricular hypertrophy was observed and the twin died 60 hours after birth from multisystemic failure. Patient 2 underwent a cesarian section at week 29 due to cardiomegaly and cardiac insufficiency in the recipient twin. At birth, he showed hypertension and poor peripheral perfusion. Biventricular hypertrophy was observed, which increased until it produced a mild right midventricular stenosis at 72 hours, decreasing after the 8th day. Mild hypertrophy persisted at 6 months of life.

DISCUSSION

Cardiovascular alterations appear only in recipient fetuses affected by twin-twin transfusion syndrome. The most frequent findings are cardiac dilation, hypertrophy, myocardial dysfunction, tricuspid regurgitation and pulmonary stenosis. These alterations usually disappear during the first few months of life, but may also worsen.

Current concepts in fetal cardiovascular disease

This article discusses the unique properties of the fetal cardiovascular system and patterns of blood flow in congenital heart disease. It also explores the complex interactive dependency between the developing heart and pulmonary vasculature, with particular attention to hypoplastic left heart syndrome. The article goes on to highlight some recent advances in the understanding of fetal cardiovascular medicine, specifically the possibilities and prognosis for fetal cardiac interventions. An understanding of the enigmatic process of twin-twin transfusion syndrome may help in elucidating one of the mechanisms for development of cardiac structural abnormalities in the fetus.

[Neurological outcome of children from twin pregnancies]

The neurological outcome is an important issue regarding twin pregnancies. In fact, twin pregnancy is clearly associated with an important neurological morbidity, roughly 4 times higher than singleton pregnancy. It is possible to distinguish some high-risk situations, making it possible to calculate more accurately the individual risk. The different aetiologies are analysed: hypotrophy, prematurity, malformations, prenatal occurrence of anoxic and ischemic lesions, and particularly the link with monochorionicity. The neurological outcome is mainly depending on hypotrophy and prematurity. However, the rate of long-term neurological complications is not different between twins and singletons after adjustment for term and birth weight. An increased risk of malformation is associated with twin pregnancies, essentially a high rate of abnormal neural tube closing (RR=2). Monochorionic pregnancies have a specific morbidity, not related to these aetiologies, with characteristic anoxic and ischemic lesions. Cerebral palsy is observed in 10-20% of the monochorionic pregnancies, vs 3.7% of the bichorionic ones. These complications are linked to the constant vascular anastomoses, between the circulations of the two monochorionic twins. When the twin-to-twin transfusion syndrome is severe, a poor neurological outcome is observed in 4 to 18% of the surviving children. However, this rate depends on studies, treatments, and methods of neurological evaluation. The laser destruction of anastomoses could decrease this morbidity. The stillbirth rate, either associated or not with twin to twin transfusion syndrome, is increased by monochorionicity. The death of one of the twins is associated with a 20% higher risk of neurological sequelae for the surviving co-twin.

Neonatal outcome in twin-to-twin transfusion syndrome treated with fetoscopic laser occlusion of vascular anastomoses

OBJECTIVE

To determine neonatal mortality and morbidity rates in monochorionic twins with chronic twin-to-twin transfusion syndrome (TTTS) treated with fetoscopic laser occlusion of vascular anastomoses.

STUDY DESIGN

In a prospective study of monochorionic twins delivered at our center between June 2002 and December 2004, neonatal outcome was assessed in 40 monochorionic twin pairs with TTTS treated with laser compared with 46 monochorionic twin pairs without TTTS.

RESULTS

The neonatal mortality rate in the TTTS and no-TTTS group was 8% (6/76) and 3% (3/90), respectively. The rate of severe cerebral lesions on ultrasound scanning in the TTTS and no-TTTS group was 14% (10/72) and 6% (5/82), respectively. The incidence of adverse neonatal outcome (neonatal death, major neonatal morbidity, or severe cerebral lesions) in the TTTS and no-TTTS group was, respectively, 26% (20/76) and 13% (12/90) (RR = 1.97, 95% CI = 1.03 to 3.77).

CONCLUSIONS

Although perinatal outcome in TTTS has improved after laser therapy, neonatal mortality and morbidity rates remain high. Relative risk for adverse neonatal outcome is increased 2-fold in TTTS treated with laser relative to monochorionic twins without TTTS.

Management of twin-twin transfusion syndrome in pregnancies with iatrogenic detachment of membranes following therapeutic amniocentesis and the role of interim amniopatch

OBJECTIVE

Detachment of membranes may occur after therapeutic amniocentesis for twin-twin transfusion syndrome (TTTS). Subsequent amniocenteses or endoscopic fetal therapy may be hindered or made altogether impossible by this complication. The purpose of this study was to describe our experience in the assessment and management of TTTS patients with iatrogenic detached membranes (IDM).

METHODS

Patients with IDM referred for fetal surgery for TTTS were considered ineligible for standard surgery and were offered different alternatives, including expectant management, serial amniocentesis, or an attempt at surgery with or without prior amniopatch. Pregnancy outcomes were compared between surgical and non-surgical patients.

RESULTS

Nine hundred and forty-four patients with a diagnosis of TTTS were referred between July 1997 and December 2004, of whom 322 (34.1%) had a prior therapeutic amniocentesis. Twenty-six of the 322 patients (8%) had IDM. Ten patients opted to be managed with subsequent amniocenteses, two of which had an amniopatch. One patient had voluntary interruption of pregnancy. Fifteen patients underwent surgery, 10 of whom underwent an amniopatch. Overall, resealing of membranes occurred in 8/12 (66%) patients treated with an amniopatch. Survival of at least one fetus was greater in patients treated surgically with or without an amniopatch (12/15, 80% vs. 4/11, 36%, P = 0.04).

CONCLUSION

Membrane detachment is an important complication of therapeutic amniocentesis in the treatment of TTTS. Although successful treatment of IDM can be achieved with an interim amniopatch, this alternative is not without risks. Therapeutic amniocenteses should be discouraged in patients considering endoscopic fetal surgery for TTTS.

Twin-twin transfusion syndrome: where do we go from here?

Management of Twin-Twin Transfusion Syndrome (TTTS) is one of the most challenging clinical problems concerning multiple gestations. The pathophysiology of TTTS and Quintero staging system are described. The importance of fetal echocardiograms in assessing prognosis and response to therapy is highlighted. Treatment modalities, particularly amnioreduction, microseptostomy, and fetoscopic laser photocoagulation, are discussed. Questions still remain as to how various treatment options affect short- and long-term cardiac and neurodevelopmental outcomes and which patients will benefit most from selective laser photocoagulation therapy.

A randomized trial of amnioreduction versus septostomy in the treatment of twin-twin transfusion syndrome

OBJECTIVE

Left untreated, severe twin-to-twin transfusion syndrome (TTTS) presenting in the early second trimester of pregnancy is often associated with significant maternal morbidity and almost universal perinatal loss. Removal of excessive amounts of amniotic fluid through serial amniocenteses (amnioreduction) has been the mainstay of therapy. We sought to compare amnioreduction to intentional perforation of the intervening twin membrane (septostomy).

STUDY DESIGN

Pregnant women with TTTS before 24 weeks' gestation were randomly assigned to serial amnioreduction or septostomy. A single puncture technique under ultrasound guidance was used for the septostomy. The primary outcome measure was survival to neonatal discharge, and was assessed based on the number of pregnancies or the number of fetuses as appropriate.

RESULTS

The study was terminated at the planned interim analysis stage after 73 women were enrolled. This was because the rate of survival of at least 1 infant was similar in the amnioreduction group compared to the septostomy group (78% vs 80% of pregnancies, respectively; RR=0.94, 95%CI 0.55-1.61; P=.82). Patient undergoing septostomy were more likely to require a single procedure for treatment (64% vs 46%; P=.04).

CONCLUSION

Although overall perinatal survival is not enhanced, septostomy offers the advantage of often requiring a single procedure compared to serial amnioreduction in the treatment of severe twin-to-twin transfusion syndrome.

What--and why--the pediatric surgeon should know about twin-to-twin transfusion syndrome

Abstract Endoscopic laser ablation of placental vessels is the most commonly performed fetal operation today. Herein, we review the pathophysiology of twin-to-twin transfusion syndrome and the challenges of its treatment. Pediatric surgeons, with their knowledge of fetal and congenital pathology, and their technical expertise with minimally invasive surgery, can be of great benefit to the patient and the medical team.

Monochorionic twin pregnancies

The monochorionic placenta should be considered a developmental malformation and, as such, represents one of the most common birth defects. Great strides are being made to unravel the progression of nature's successful attempt at human cloning through fission. Critical to any strategy to reduce the perinatal morbidity and mortality associated with monochorionic placentas is early detection. Intense surveillance in at risk pregnancies will provide a better understanding of their natural progression, improve the prognosis with early intervention, and ultimately provide the key to prevent many of the complications unique to the monochorionic placenta.

Antepartum management of multifetal pregnancies

Correct antepartum management of multifetal gestations is a critical skill for practitioners of obstetrics. This article reviews important issues surrounding these complicated pregnancies while discussing current management options and recommendations. Topics include antepartum surveillance, preterm labor prediction, diagnosis, and management, and special situations unique to multiple gestations, such as twin-twin transfusion syndrome and death of one twin in utero. It is the authors' hope that this article is comprehensive in enhancing the reader's knowledge of these complex pregnancies.

Contemporary Treatments for Twin–Twin Transfusion Syndrome

OBJECTIVE

To undertake a systematic review to determine the effects of fetal therapy interventions compared with amniodrainage for twin-twin transfusion syndrome on perinatal survival and outcome.

METHODS

Searching MEDLINE (1966-2004), EMBASE (1988-2004), a hand search of specialist journals, and the Cochrane library (2004:2) identified relevant articles. Studies were selected if the effects of fetal therapeutic interventions for twin-twin transfusion syndrome (laser photocoagulation, serial amnioreduction, septostomy, and selective feticide) on perinatal survival, complications, and morbidity were compared. Study selection, quality assessment, and data abstraction were performed independently and in duplicate.

RESULTS

Only 3 controlled observational studies (comparing treatment in 306 twins) and 1 randomized controlled trial (of 142 twins) were identified. Laser photocoagulation significantly improved perinatal survival of at least 1 fetus and reduced neurologic morbidity compared with serial amnioreduction. No such differences were observed in the comparison of serial amnioreduction with septostomy.

CONCLUSION

In a systematic review of observational and randomized controlled studies, laser photocoagulation of chorionic plate vessels at the intertwin membrane seems to be more effective than serial amnioreduction in the treatment of twin-twin transfusion syndrome with less associated perinatal morbidity and mortality. However, septostomy and selective feticide have not been robustly evaluated.

Prevalence of cranial scan abnormalities in preterm twins in relation to chorionicity and discordant birth weight

OBJECTIVE

The purpose of this study was to determine the incidence of ultrasonographically detected cerebral white matter lesions (WMLs) in preterm twins at birth in relation to chorionicity, discordant weight and twin-twin transfusion syndrome (TTTS).

METHODS

In this retrospective study, perinatal, neonatal, and cranial scan data of 85 monochorionic (MC) and 94 dichorionic (DC) twin pregnancies (341 infants) delivered between 24 and 34 weeks of gestation were collected. Data were analysed according to chorionicity, discordant birth weight (>20%), single intrauterine death and TTTS.

RESULTS

The cerebral WML was seen in 14% of preterm twins. Monochorionic infants had higher risks of WML than DC twin (odds ratio 7.1; 95% CI 3.28-15.8). In MC group, discordant weight (37%), TTTS (38%), single intrauterine death (67%) had higher incidence of cerebral WML than concordant weight infants (7%). Similarly, incidence of WML was higher in DC discordant compared with concordant weight infants (13% versus 2%; P < 0.05).

CONCLUSION

Monochorionic infants had a seven-fold higher incidence of cerebral WML than DC infants. Discordant birth weight, TTTS and survivor of co-twin demise are an independent risk of cerebral white matter lesion.

Discordant growth in twins

Discordant growth in twins contributes significantly to rates of perinatal morbidity and mortality. These rates vary according to chorionicity, timing of onset and severity. We have reviewed English language literature in Medline since 1980. It is clear that diagnosis of discordant growth has improved due to the use of serial ultrasound examination. Following the detection of differences in fetal size, diagnosis is facilitated by umbilical artery and fetal Doppler studies. Management options vary according to chorionicity, timing of onset and umbilical-fetal Doppler studies. The mode of delivery in discordant twins remains controversial. We conclude that ultrasound surveillance of twin gestations, combining serial biometry and selective Doppler studies, is effective in the recognition of significant intrauterine growth restriction in co-twins. Differences in etiology and management underscore the importance of establishing chorionicity routinely as soon as twin gestation is diagnosed.

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.

Management of fetofetal transfusion syndrome

Feto-fetal transfusion syndrome contributes heavily to high rates of perinatal mortality and morbidity in monochorionic multiple pregnancies. Its prenatal management has been controversial for at least 25 years. We review the recent literature in order to present the basis for a pragmatic reappraisal of the management of this condition. Laser surgery of the chorionic plate inter-twin anastomoses is the best first-line treatment when the syndrome develops before 26 weeks' gestation. Survival (including quality of survival) and gestational age at delivery are improved when compared to serial amnioreduction. Second-line treatment options include repeat-laser, intra-uterine blood transfusion, serial amnioreduction, selective feticide using bipolar cord coagulation or elective delivery, depending upon gestational age and the severity of the disease and its complications. We have found that fetoscopic placental surgery has proven itself over simplicity of amnioreduction. There is no evidence that treatment should be customized according to the stage of the disease at diagnosis. Early recognition of the syndrome through fortnightly serial ultrasound follow-up of all monochorionic pregnancies should ensure timely referral and make up for geographical constraints. Laser surgery should now be available in fetal medicine units that are managing at least 20 cases per year.

Insights into the pathophysiology of twin–twin transfusion syndrome

Twin-twin transfusion syndrome (TTTS) is attributed to trans-anastomotic transfusion between twins. Anastomoses are ubiquitous in monochorionic (MC) placentae, yet TTTS develops in only 15%. Although ex vivo and in vivo studies fail to identify a unique anastomotic signature, TTTS placentae are typically associated with an imbalance in unidirectional arteriovenous anastomoses with absent bidirectional anastomoses. Doppler detection of an artery-artery anastomosis reduces the chance of TTTS, whereas, in those that develop the disease, it improves stage-independent survival. Selective laser is often curative, but an increasingly recognized risk of persistent or reverse TTTS may be attributable to atypical arteriovenous anastomoses not identifiable from the chorionic plate. Simple dysvolaemia fails to explain several phenotypic features, including haematological concordancy, recipient hypertension, and reversibly absent end diastolic flow in the donor. The renin-angiotensin system is upregulated in the donor and downregulated in the recipient's kidneys, while paradoxically raised renin levels in the recipient may contribute to raised afterload along with endothelin. Although research is limited in humans by therapy and the lack of a suitable experimental model, further studies of placental and vascular pathophysiology may not only refine current treatment modalities but may also, in addition, suggest further avenues for downstream management such as genetic predisposition testing or pharmacological intervention.

Twin–Twin Transfusion Syndrome: A Population-Based Study

OBJECTIVE

To study the incidence and mortality and morbidity rates of twin-twin transfusion syndrome in a complete population-based cohort in Nova Scotia.

METHODS

A population-based cohort study of all monochorionic diamniotic twin pregnancies of 20 weeks of gestation or longer born to Nova Scotia (Canada) residents between 1988 and 2000 was examined. The effect of gestational age adjustment and birth weight discordancy of more than 20% on mortality and 1-year survival was studied. Other outcomes studied included birth depression, respiratory distress syndrome, chronic lung disease, interventricular hemorrhage, periventricular leukomalacia, acute renal failure, and congestive heart failure.

RESULTS

Of 404 monochorionic-diamniotic twin pregnancies examined, 48 were identified with twin-twin transfusion syndrome. Total mortality rates per pregnancy were significantly greater in the twin-twin transfusion syndrome group than in the remainder of our monochorionic diamniotic population (P < .01). However, when adjusted for gestational age, mortality failed to achieve statistical significance. Similarly, no differences were noted for 1-year survival and other outcomes of liveborn infants after gestational age adjustment. Discordance in birth weight predicted a higher incidence of morbid outcomes per pregnancy, but this effect was lost after gestational age adjustment.

CONCLUSION

Increased morbidity and mortality of twins with twin-twin transfusion syndrome is likely to be due to a higher incidence of preterm birth. Birth weight discordancy was not found to be an independent predictor of mortality after controlling for gestational age and twin-twin transfusion syndrome.