Endoscopic laser surgery versus serial amnioreduction for severe twin-to-twin transfusion syndrome

Fetal and neonatal haematological complications in monochorionic twins

Placental vascular anastomoses are almost invariably present in monochorionic (MC) placentas. These anastomoses are the essential anatomical substrate for the development of several haematological complications in MC twins, in particular twin-to-twin transfusion syndrome (TTTS). Several forms of TTTS have been described, including chronic TTTS, acute perimortem TTTS, twin anaemia-polycythaemia sequence, acute perinatal TTTS and twin reversed arterial perfusion sequence. A significant evolution in prenatal care strategies and management options for patients with TTTS has occurred during the last decade. In chronic TTTS, endoscopic laser ablation of communicating placental vessels has led to an increase in survival rates. This review analyzes the possible pathophysiologic mechanisms involved, discusses the latest findings in diagnosis, therapy and prognosis, and focuses on fetal and neonatal haematologic complications associated with the various forms of TTTS.

Arterio-venous flow between monochorionic twins determined during intra-uterine transfusion. Nonlinear decay of adult red blood cells

Recently, we derived equations relating the flow of adult red blood cells through a placental arterio-venous anastomosis with intra-uterine and post-natal measured adult hemoglobin concentrations. In this letter, we re-derived the equations, now including a more realistic nonlinear decay of adult red blood cells, and re-evaluated the measurement accuracy of the arterio-venous flow and the lifetime of the red blood cells.

Fetal growth after laser therapy for twin-twin transfusion syndrome

OBJECTIVE

The objective of the study was to compare twin weight discordance and prevalence of intrauterine growth restriction (IUGR) before laser therapy and after birth in pregnancies complicated by twin-twin transfusion syndrome (TTTS).

STUDY DESIGN

Women with TTTS who underwent laser therapy with dual neonatal survivors born at least 28 days after surgery were studied. Estimated fetal weight (EFW) discordance at the preoperative sonogram and birthweight (BW) discordance were calculated. Weights below gestational age-corrected 10th percentile at sonogram and at birth for each twin were designated as IUGR.

RESULTS

Among 211 women studied, the mean EFW discordance measured 26.6% and mean BW discordance was 18.4%, yielding a mean 8.2% decrease in weight discordance (P < .001). Comparing IUGR diagnoses before surgery and at birth, the recipient's proportion was unchanged (9.5% vs 7.1%, P = .353), whereas the donor's proportion decreased (64.5% vs 28.9%, P < .001).

CONCLUSION

Twin weight discordance and donor fetus IUGR appear to improve after laser therapy for TTTS.

Initial fetal cardiovascular profile score predicts recipient twin outcome in twin-twin transfusion syndrome

BACKGROUND

The aim of this study was to assess the relationship between cardiomyopathy and recipient twin (RT) outcome in twin-twin transfusion syndrome (TTTS).

METHODS

Fetal echocardiography and outcomes data in 62 consecutive pregnancies with TTTS were reviewed. The primary outcome was neonatal RT survival. The severity of RT cardiomyopathy at presentation was assessed by the cardiovascular profile score (CVPS). RT outcomes and odds of survival were compared between groups stratified by CVPS.

RESULTS

Overall neonatal survival for all fetuses was 61% (76 of 124). RT survival was 58% (36 of 62). Grouped by CVPS, RT survival was greater (50%) for those with CVPS > or = 9 and even higher (74%) for CVPS of 10. Among the components of the CVPS, atrioventricular valve regurgitation was associated with negative RT outcome. Other factors at presentation were not predictive of RT outcome.

CONCLUSIONS

A normal CVPS in the RT in TTTS is predictive of improved survival compared with an abnormal CVPS, even in RTs with minor deductions. Standard clinical staging did not predict outcome. Cardiac assessment by CVPS may improve clinical decision making and the timing of fetal interventions.

Growth abnormalities and multiple gestations

Growth abnormalities which include intrauterine growth restriction and weight discordance between twins are common in pregnancies complicated by multiple gestations and may be associated with poor perinatal outcomes. Knowledge of chorionicity is paramount when managing a multiple pregnancy. Monochorionic twins are at greater risk than dichorionic twins for growth issues, which may result in long-term complications including adverse neurological sequelae for the offspring. The purpose of the following article is to define normal and abnormal growth in multiples. In addition, the management of growth abnormalities in relationship to chorionicity will be discussed.

Interventions for twin-twin transfusion syndrome: a Cochrane review

We performed a Cochrane review to assess which of the treatments for twin-twin transfusion syndrome (TTTS) improves fetal, childhood and maternal outcomes. This article represents a version of the review which includes additional data to the published version. We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (April 2007) and the Cochrane Central Register of Controlled Trials (The Cochrane Library, October 2007) for randomized and quasi-randomized studies of amnioreduction, laser coagulation and septostomy and compared their outcomes. We also searched conference proceedings and contacted the authors of published trials for clarification and additional data. No trials compared intervention with no intervention. Three studies (253 women) were included. Laser coagulation resulted in less overall death (48% vs. 59%; relative risk (RR), 0.81; 95% CI, 0.65-1.01 adjusted for clustering; two trials, 364 fetuses), perinatal death (26% vs. 44%; RR, 0.59; 95% CI, 0.40-0.87 adjusted for clustering; one trial, 284 fetuses) and neonatal death (8% vs. 26%; RR, 0.29; 95% CI, 0.14-0.61 adjusted for clustering; one trial, 284 fetuses) when compared with amnioreduction. There was no difference in perinatal outcome between amnioreduction and septostomy. More babies were alive without neurological abnormality at the age of 6 months in the laser group than in the amnioreduction group (52% vs. 31%; RR, 1.66; 95% CI, 1.17-2.35 adjusted for clustering; one trial). There was no difference in the proportion of babies alive at 6 months that had undergone treatment for major neurological abnormality between the laser coagulation and the amnioreduction groups (4% vs. 7%; RR, 0.58; 95% CI, 0.18-1.86 adjusted for clustering; one trial). The results suggest that endoscopic laser coagulation of anastomotic vessels should be considered in the treatment of all stages of TTTS to improve perinatal and neonatal outcome.

Congenital heart disease in twin-to-twin transfusion syndrome treated with fetoscopic laser surgery

OBJECTIVE

To determine the incidence of congenital heart disease (CHD) and right ventricular outflow tract obstruction (RVOTO) in twin-to-twin transfusion syndrome (TTTS) treated with fetoscopic laser surgery and evaluate the role of increased afterload by determining the difference in blood pressure and endothelin-1 at birth between donor and recipient twins.

DESIGN

Prospective study.

SETTING

Tertiary medical center, serving as the national referral center for fetoscopic laser surgery for TTTS in The Netherlands.

PATIENTS

All consecutive cases of monochorionic twins with TTTS treated with laser (n = 46 twin pairs) and monochorionic twins without TTTS (n = 55 twin pairs) delivered at our center between June 2002 and June 2005 were included in the study.

INTERVENTIONS

Echocardiography was performed within 1 week after delivery. At birth, blood pressure was measured in all survivors and endothelin-1 was determined in umbilical cord blood. Data on RVOTO in TTTS treated with laser surgery at our center but delivered elsewhere were reviewed retrospectively from medical records.

RESULTS

The incidence of CHD in the TTTS group and non-TTTS group was 5.4% (4/74) and 2.3% (2/87) (P = .42), respectively. RVOTO was diagnosed in 1 recipient twin delivered at our center and 2 recipient twins delivered elsewhere. The incidence of RVOTO in recipients was 4% (3/75). Mean systolic blood pressure at birth was similar in donor and recipient twins, respectively, 53 mm Hg vs. 56 mm Hg (P = .42). Mean endothelin-1 level at birth was also similar between donors and recipients, respectively, 14.3 ng/L and 13.2 ng/L (P = .64).

CONCLUSION

The incidence of CHD in TTTS treated with fetoscopic laser surgery is higher than in the general population (5.4% vs. 0.5%). We found no difference in afterload parameters between donors and recipients after laser treatment.

Fetal surgery

Fetal surgery has emerged from the realm of medical curiosity into an exciting, multidisciplinary specialty now capable of improving patient outcomes for a wide variety of diseases. Recent advances allow prenatal providers to both accurately diagnose and treat many fetal anomalies while maintaining maternal safety. As the initial postnatal health care providers to the majority of these newborns, neonatologists need to be familiar with some of the more recent state-of-the-art procedures currently being used. In this review, the authors discuss the prenatal evaluation process and various operative approaches (ie, open hysterotomy, fetoscopy, and percutaneous) to conduct fetal surgery. They then analyze the effectiveness of some of the more established and experimental prenatal therapies that are being performed for a number of fetal anomalies, including twin-twin transfusion syndrome, thoracic malformations, airway obstruction, congenital diaphragmatic hernia, myelomeningocele, and aortic valve stenosis.

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.

Pseudoamniotic band syndrome: a rare complication of monochorionic twins with fetofetal transfusion syndrome treated by laser coagulation

OBJECTIVE

The purpose of this study was to assess the incidence and risk factors of limb constriction defects that are related to pseudoamniotic band syndrome (PABS) after selective fetoscopic laser surgery (FLS) in fetofetal transfusion syndrome (FFTS).

STUDY DESIGN

All consecutive cases of FFTS that were treated by selective FLS between 1999 and 2006 were examined prospectively for PABS at the time of delivery. Incidence and characteristics of PABS were reported. Univariate analysis was conducted to look for potential risk factors of developing PABS.

RESULTS

The 438 consecutive FFTS cases were treated at 15-26 weeks of gestation; PABS developed in 8 cases (1.8 %). The affected twin was always the former recipient. The diagnosis was made prenatally in 2 of 8 cases (25%). All cases survived the perinatal period. PABS affected fetal leg, arm, and foot in 3, 4, and 1 cases, respectively. In 5 (62.5%) and 7 (87.5%) cases, PABS occurred after premature rupture of membranes and intrauterine death of the donor, respectively. In 4 cases (50%), there was both premature rupture of membranes (PROM) and intrauterine fetal death; in 3 cases (37.5%), there was intrauterine fetal death alone, and in 1 case (12.5%), there was PROM alone. In the remaining 430 cases, PROM occurred in 62 cases (14.4%) and 66 cases (15.3%) within and after 3 weeks after surgery, respectively. PROM was significantly more frequent within the group that was complicated with PABS than within the rest of the cohort (P = .05). No maternal, fetal, or perioperative risk factor could be identified.

CONCLUSION

Awareness and targeted serial ultrasound evaluation in this high-risk group may improve prenatal diagnosis, counseling, and management of PABS after FLS.

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.

Radiofrequency ablation for selective reduction in the complicated monochorionic gestation

OBJECTIVE

This study was undertaken to describe the efficacy and safety of radiofrequency ablation for selective reduction in the treatment of complicated monochorionic gestations.

STUDY DESIGN

Case series of all consecutive patients treated at 1 institution. A 17-gauge radiofrequency needle was inserted under continuous ultrasound guidance into the fetal abdomen at the site of the umbilical cord insertion of the affected twin and radiofrequency energy delivered until cessation of vascular flow was documented with pulsed and color flow Doppler.

RESULTS

Nine patients with monochorionic twin gestations (1 set was part of a triplet gestation) underwent the radiofrequency ablation procedure. Gestational age at the procedure ranged between 18.6-22 weeks. Liveborn infants resulted in two-thirds of cases. Preterm premature rupture of the membranes occurred in 2 of the 9 cases. All liveborn neonates were alive and well.

CONCLUSION

Radiofrequency ablation can be effectively used for selective reduction in complicated monochorionic gestations.

Fetoscopic laser treatment of twin-to-twin transfusion syndrome followed by severe twin anemia-polycythemia sequence with spontaneous resolution

We present a case of twin anemia-polycythemia sequence after laser surgery for twin-to-twin transfusion syndrome which resolved spontaneously. No residual anastomoses were identified after placental injection with colored dye. We discuss the possible pathogenetic mechanisms that may have led to this remarkable clinical course and discuss the various management options.

Laser therapy and serial amnioreduction as treatment for twin-twin transfusion syndrome: a metaanalysis and review of literature

OBJECTIVE

The objective of the study was to review current controversy on laser therapy (LT) vs serial amnioreduction (SA) performed for twin-twin transfusion syndrome (TTTS).

STUDY DESIGN

A search in PubMed from 1997-2007 was performed. Inclusion criteria were diamniotic monochorionic pregnancy, TTTS diagnosed with standard parameters, and peri- and neonatal outcomes well defined. Triplets and investigations on other topics of TTTS rather than perinatal outcomes were excluded. A metaanalysis was performed by fixed-effect model (heterogeneity <25%).

RESULTS

Ten articles provided 611 cases of TTTS (LT: 70%; SA: 30%) and included 4 studies comparing the 2 treatments (395 cases: LT, 58%; SA, 42%). Fetuses undergoing LT were more likely to survive than fetuses undergoing SA (overall survival rate: P < .0001; odds ratio [OR], 2.04; 95% confidence interval [CI], 1.52-2.76; neonatal death: P < .0001; OR, 0.24; 95% CI, 0.15-0.40; neurologic morbidity: P < .0001; OR, 0.20; 95% CI, 0.12-0.33).

CONCLUSION

This metaanalysis shows that LT is associated with better outcomes than SA and proposes new topics for future research.

The effect of fetoscopic laser therapy on fetal cardiac size in twin-twin transfusion syndrome

OBJECTIVES

To evaluate the influence of fetoscopic laser therapy on fetal cardiac size in monochorionic twins complicated by twin-twin transfusion syndrome (TTTS).

METHODS

In a longitudinal, prospective study, we assessed fetal cardiac size sonographically in monochorionic diamniotic twins with TTTS treated by laser therapy and in monochorionic twins without TTTS. The fetal cardiothoracic ratio (cardiac circumference divided by thoracic circumference) of TTTS twins was determined within 24 h before, 12-24 h after and 1 week after laser treatment, and from then on every 2-4 weeks until birth. TTTS twins were classified into Quintero Stages 1-2 (n = 18) and Stages 3-4 (n = 16), and measurements were compared with biweekly measurements of non-TTTS monochorionic twins matched for gestational age (n = 38). Cardiomegaly was defined as a cardiothoracic ratio above the 97.5th percentile.

RESULTS

Before laser treatment, cardiomegaly was observed in 44% (8/18) and 50% (8/16) of recipients in Quintero Stages 1-2 and Stages 3-4, respectively. Cardiomegaly occurred in none of the donors before treatment. After laser treatment, cardiomegaly was observed in 76% (13/17) and 50% (7/14) of recipients in Stages 1-2 and Stages 3-4, respectively, and in 17% (3/18) and 13% (2/15) of donors in Stages 1-2 and Stages 3-4, respectively. Cardiomegaly was present in 18% (7/38) and 8% (2/25) of non-TTTS monochorionic twins and singletons. After laser therapy, the cardiothoracic ratio of recipients in Stages 1-2 and Stages 3-4 was not significantly changed (P = 0.34 and P = 0.67, respectively). The cardiothoracic ratio of donors in Stages 1-2 and Stages 3-4 was increased compared with that before laser therapy (P = 0.0002 and P = 0.005, respectively). Cardiothoracic ratios of non-TTTS monochorionic twins were not significantly different from our reference range in singletons throughout gestation, and were smaller than those in both recipients and donors after laser therapy.

CONCLUSIONS

TTTS recipients show cardiomegaly before as well as after fetoscopic laser therapy for TTTS. Donors develop cardiomegaly only after laser treatment. Our findings emphasize the significant effect of TTTS and fetoscopic laser therapy on the fetal heart of both recipient and donor twins.

Interventions for the treatment of twin-twin transfusion syndrome

BACKGROUND

Twin-twin transfusion syndrome, a condition affecting monochorionic twin pregnancies, is associated with a high risk of perinatal mortality and morbidity. A number of treatments have been introduced to treat the condition but it is unclear which intervention improves maternal and fetal outcome.

OBJECTIVES

The objective of this review was to evaluate the impact of treatment modalities in twin-twin transfusion syndrome.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (October 2007) and the Cochrane Central Register of Controlled Trials (The Cochrane Library 2007, Issue 4). We also searched conference proceedings and made personal contact with experts active in the area of the review.

SELECTION CRITERIA

Randomised and quasi-randomised studies of amnioreduction versus laser coagulation, septostomy versus laser coagulation or septostomy versus amnioreduction.

DATA COLLECTION AND ANALYSIS

One review author assessed eligibility and extracted data, which were checked by a second author. We contacted study authors for additional information.

MAIN RESULTS

Two studies (213 women) were included. This review shows that laser coagulation of anastomotic vessels results in less death of both infants per pregnancy (relative risk (RR) 0.33; 95% confidence interval (CI) 0.16 to 0.67, one trial), less perinatal death (RR 0.59; 95% CI 0.0.40 to 0.87 adjusted for cluster, one trial) and less neonatal death (RR 0.29; 95% CI 0.14 to 0.61 adjusted for cluster, one trial) than in pregnancies treated with amnioreduction. There is no difference in perinatal outcome between amnioreduction and septostomy. A third study is awaiting assessment. More babies were alive without neurological abnormality at the age of six months in the laser group than the amnioreduction groups (RR 1.66; 95% CI 1.17 to 2.35 adjusted for clustering, one trial). This difference did not persist beyond six months of age. There was no significant difference in the babies alive at six months with neurological abnormality treated by laser coagulation or amnioreduction (RR 0.58; 95% CI 0.18 to 1.86 adjusted for clustering, one trial).

AUTHORS' CONCLUSIONS

Endoscopic laser coagulation of anastomotic vessels should be considered in the treatment of all stages of twin-twin transfusion syndrome to improve perinatal outcome. Further research on the effect of treatment on milder forms of twin-twin transfusion syndrome (Quintero stage 1 and 2) are required. The long-term outcomes of survivors from the studies included in this review are required.

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.

Early manifestations and spectrum of recipient twin cardiomyopathy in twin-twin transfusion syndrome: relation to Quintero stage

OBJECTIVES

To examine cardiac structural and functional changes in twin-twin transfusion syndrome (TTTS), relative to Quintero stage, as a means of evaluating the spectrum of cardiomyopathy in TTTS.

METHODS

This was a cross-sectional, retrospective study of 42 consecutive cases of TTTS referred to a single fetal therapy center. Quintero stages were assigned by standard criteria. Presence of ventricular hypertrophy, cardiomegaly, atrioventricular valve regurgitation (AVVR), ventricular systolic dysfunction and right ventricular outflow tract obstruction on fetal echocardiography were noted. The Doppler myocardial performance index (MPI), an index of global ventricular function, was calculated for both ventricles in subjects with adequate Doppler data. We compared cardiac changes across Quintero stages.

RESULTS

There was no cardiomyopathy observed in donor twins. The majority of subjects presented at Quintero Stage I (n = 14), II (n = 14) or III (n = 11), with fewer at Stages IV (n = 2) or V (n = 1). As early as Quintero Stages I and II, a significant proportion of recipient twins had ventricular hypertrophy (17/28, 61%), AVVR (6/28, 21%) or quantitative abnormalities in either right (12/24, 50%) or left (14/24, 58%) ventricular function. Increasing prevalence of biventricular systolic dysfunction and cardiomegaly accompanied advancing Quintero stage.

CONCLUSIONS

Changes in cardiac structure and function not reflected in Quintero staging occur in recipient twins early in the evolution of TTTS. Incorporation of cardiac findings into assessment of TTTS severity may prove useful in stratification of risk and treatment selection.

Relevance of measuring diastolic time intervals in the ductus venosus during the early stages of twin-twin transfusion syndrome

OBJECTIVE

To determine if the discrete myocardial diastolic dysfunction documented previously in the recipient twin during the early stages of twin-twin transfusion syndrome (TTTS) has any repercussion on flow velocities through the ductus venosus (DV) and to investigate if this could allow early differentiation between TTTS and selective intrauterine growth restriction (IUGR).

METHODS

Two groups of monochorionic twin pregnancies with growth discordance between twins were reviewed retrospectively. Group I was composed of fetuses in Stages I and II of TTTS; laser or amnioreduction was not performed in any instance. Group II twin pairs each included one fetus with IUGR due to placental circulatory insufficiency. Intertwin differences (smaller minus larger fetus) were analyzed for myocardial performance index of the right ventricle (MPI-RV) and for time variables in the DV.

RESULTS

There were 38 pairs of monochorionic twins (24 TTTS and 14 IUGR) in this study. In the TTTS group, the donors had a significantly lower MPI-RV (0.419 +/- 0.18 vs. 0.596 +/- 0.17, F(1,19df) = 24.017, P < 0.001), a significantly longer total ventricular filling time (150.9 +/- 25.6 ms vs. 124.0 +/- 22.6 ms; F(1,21df) = 19.631, P < 0.001) and a significantly longer early filling time (118.9 +/- 22.9 ms vs. 92.6 +/- 18.9 ms, F(1,21df) = 28.419, P < 0.001) than had the recipient. None of these three differences was present in the IUGR group. Probability studies revealed that cut-off values of 12.75 for intertwin differences in total filling time and 8.5 for intertwin differences in early filling time had sensitivities of 71% and 92%, respectively. The false-positive rates were 23% and 15%, respectively, for the early diagnosis of TTTS.

CONCLUSION

In monochorionic twin pregnancies, shortening of the ventricular filling time in the recipient twin indicates diastolic myocardial dysfunction occurring early in the pathophysiology of TTTS. This early interwin difference in myocardial function is not found in pregnancies with IUGR in one twin due to placental circulatory insufficiency, allowing early differentiation between TTTS and selective IUGR.

Laser treatment in twin-to-twin transfusion syndrome

Twin-to-twin transfusion syndrome (TTTS) is a severe fetal condition that has regained attention since surgical endoscopic treatment proved beneficial in a randomized controlled trial. Our objective is to review published series of cases treated with fetoscopic surgery. Diagnostic criteria, surgical technique, and perinatal outcome of series of TTTS cases treated by laser were reviewed. Over 1300 cases from 17 publications have been included, with a median perinatal survival rate of 57% (50-100%); brain lesions were present in 2-7% of the survivors at the age of 1-6 months. The percutaneous technique has gained wide acceptance, with an acceptable risk of maternal morbidity but a significant risk of miscarriage or preterm rupture of the membranes, presenting in 6.8-23% and 5-30%, respectively. The conclusion is that standardization of the technique and stability to improvement of the initial results should broaden the use of this technique. The overall survival rate at birth was 66% (1894/2869). However, variations in survival rates between centres and inconsistency in the reporting of complications call for more homogeneity in the pre- and post-operative assessment.

Fetal intervention for cardiac disease: the cutting edge of perinatal care

Fetal cardiac valvuloplasty has been proposed for progressive cardiac disease with a poor prognosis, such as critical aortic stenosis and pulmonary atresia with intact ventricular septum and balloon atrial septostomy for hypoplastic left heart syndrome, or simple transposition of the great arteries with closed or restrictive inter-atrial communication. It is anticipated that early rescue of ventricles or the pulmonary veins from an unfavourable environment may promote healthier ventricular and vascular growth and improve postnatal outcomes. While close collaboration between the fetal medicine specialist and perinatal cardiologist may optimize the chances of technical success, obstacles to progress include the relative rarity of suitable cases and late referral for therapy. In common with other interventions in fetal medicine, there is a learning curve, and it would benefit progress if the procedures were initially concentrated in just a few centres to enable them to develop skills and experience. Following careful evaluation, it may then be desirable to train further centres and roll out best practice models.

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.

Three-dimensional sonographic assessment of fetal urine production before and after laser surgery in twin-to-twin transfusion syndrome

OBJECTIVE

Fetal urine production in twin-to-twin transfusion syndrome (TTTS) reflects the hemodynamic imbalance between the donor and recipient twins but it has not been measured in this particular condition. The aim of this study was to measure fetal urine production using three-dimensional (3D) ultrasound in donor and recipient twins before and after laser treatment for TTTS and to correlate this with umbilical venous volume flow (UVVF).

METHODS

Urine production rate (UPR) was measured using 3D ultrasound with Virtual Organ Computer-aided AnaLysis (VOCAL) in 106 cases of severe TTTS. The rotation angle was set at 30 degrees . The bladder volume was measured twice in each fetus (V(1) and V(2)), with an interval of 5-30 min between measurements, in order to calculate the UPR. When V(2) > V(1), UPR was calculated using the formula: V(2) - V(1) /time interval. Together with UPR, UVVF was measured before and after treatment. Both parameters were corrected for fetal weight. Inter- and intraobserver variability were calculated in 16 cases using the intraclass correlation coefficient.

RESULTS

Before laser treatment, UPR was significantly higher in recipients compared with donors (median, 14.8 and 0 mL/h/kg, mean 23.8 and 2.3 mL/h/kg, respectively, P < 0.001), and UPR was positively correlated with UVVF in both twins. Following laser treatment (48 h later), UPR decreased to 9 mL/h/kg (P < 0.001) in recipients, while there was no change in donors. UVVF increased significantly from a median value of 92 to 132 mL/min/kg (P < 0.01) in donors and decreased significantly from 150 to 99 mL/min/kg (P < 0.001) in recipients.

CONCLUSIONS

In TTTS UPR is correlated to UVVF and reflects the hemodynamic imbalance between donor and recipient twins. Following laser treatment, UPR decreases in recipients but is unaffected in donors. However, changes in UVVF occur in both twins. This suggests that although fetal renal function is driven by fetal hemodynamics, there may be a lag in the recovery of renal function in the donor twin.

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.

In-utero intervention for severe congenital heart disease

The concept of fetal therapy is well established for many disorders diagnosed before birth but practical issues regarding its introduction into clinical practice are more difficult. Cardiac malformations are common, with major lesions affecting about 3.5 per thousand pregnancies; however, only a small proportion of these is likely to benefit from an intrauterine intervention. In addition, there are no good animal models of human cardiac disease and our knowledge of the underlying mechanisms is at best sketchy. This combination of factors has resulted in slow progress in developing effective therapies for the intrauterine management of cardiac disease. Recent research and clinical developments have included percutaneous valvuloplasty for severe aortic and pulmonary stenosis, perforation of the closed or restrictive inter-atrial septum and pacing for complete heart block. Progress in these endeavours has been variable but - overall - shows promise for treatment of the human fetus.

Miniature bending manipulator for fetoscopic intrauterine laser therapy to treat twin-to-twin transfusion syndrome

BACKGROUND

Recent typical therapy for twin-to-twin transfusion syndrome (TTTS) is selective laser photocoagulation of anastomotic communicating vessels on the placenta using the fetoscopic approach. The difficulty of a conventional laser device approach for this procedure depends significantly on the placental location, so a new robotized device is required to bend the direction of laser irradiation flexibly within the narrow uterus.

METHODS

The authors designed a miniature bending mechanism impelled by a wire-guided linkage driving method that provides a stable procedure for bending laser irradiation from -90 degrees to 90 degrees . Using this bending mechanism, the authors developed a bending manipulator with a diameter of 3.5 mm and a hollow central channel with a diameter of 0.8 mm for passing a glass fiber for neodymium:yttrium-aluminum-garnet (Nd:YAG) laser photocoagulation. The bending mechanism is motorized by an electrical actuator and controlled by a grip-type interface with a small joystick. The robotized tip's part and the actuator's part are easily separable for cleaning and sterilization.

RESULTS

In performance evaluations of the manipulator, the bending characteristics with a glass fiber were examined. The bending range was -52.6 degrees to 80 degrees, with a very small hysteresis error, and the bending repeatability error was 0.5 degrees +/- 0.2 degrees, which corresponds with the high accuracy of 0.2 +/- 0.1-mm positioning error at the glass fiber's tip. In the evaluation of Nd:YAG laser photocoagulation, the study confirmed that the manipulator performed effective laser photocoagulation of the placental phantom surface (underwater chicken liver). The large bending range, reaching 80 degrees, enabled a flexible approach from various directions with a high irradiation efficiency of no less than 96.6%.

CONCLUSIONS

The authors' original miniature bending manipulator can change the laser irradiating direction with highly repeatable positioning accuracy for speedy, safe, and effective vessel occlusion in clinical practice.

Laparoscopically Guided Uterine Entry for Fetoscopy in Twin-to-Twin Transfusion Syndrome with Completely Anterior Placenta: A Novel Technique

OBJECTIVE

Laser coagulation of anastomotic vessels on the placental surface is the treatment of choice in severe second trimester twin-to-twin transfusion syndrome (TTTS). This procedure is associated with technical difficulties when the placenta is located on the anterior side of the uterus. We describe a novel technique for fetoscopy in TTTS with completely anterior placenta where laparoscopy is used to guide safe percutaneous insertion of the fetoscope through the lateral abdominal wall and the dorsal side of the uterus.

METHODS

Prospective controlled series of 16 TTTS pregnancies with completely anterior placenta (study group) treated with this novel technique. Studied outcomes were technical result of the procedure and perinatal survival. Outcome in the study group was compared with outcome of 49 TTTS pregnancies treated with conventional percutaneous fetoscopic laser without laparoscopy, 9 of these with partially anterior placenta (control group A) and 40 with lateral or posterior placenta (control group B).

RESULTS

In the study group, the procedure-related complication rate was 25% (4/16). In 1 case, uterine entry of the fetoscope from the lateral abdominal wall was not possible due to complex bowel adhesions. In 3 patients, intra-amniotic haemorrhage occurred after fetoscopic entry, preventing complete laser coagulation of anastomoses. One of these patients required 2 units of blood transfusion. The procedure-related complication rate in control groups A and B was 22% (2/9) and 5% (2/40), respectively (intra-amniotic haemorrhage n = 3, severe leakage of amniotic fluid into the peritoneal cavity, n = 1). Perinatal survival in the study group, control group A and control group B was 63% (20/32), 78% (14/18) and 70% (56/80), respectively.

CONCLUSION

Combined laparoscopy and fetoscopy is a novel technique that enables safe uterine entry and creates optimal visualisation for laser coagulation of inter-twin anastomoses in TTTS pregnancies with completely anterior placenta. The procedure-related complication rate and perinatal survival rate were similar compared to the conventional percutaneous technique. Procedure-related complications occur more often with partially or completely anterior placenta.

Immune functions after severe twin-twin transfusion syndrome

Long-term immune functions after intrauterine laser treatment for severe twin-twin transfusion syndrome was investigated. Immunologic parameters were measured in 18 twin pairs at a median age of 3.5 years. Both donors and recipients showed no severe deficiencies in total and specific immunoglobulin concentrations.

Modeling Severely Discordant Hematocrits and Normal Amniotic Fluids After Incomplete Laser Therapy in Twin-To-Twin Transfusion Syndrome

Our objective was to explain the clinical presentations of sustained arteriovenous anastomotic transfusion of blood after incomplete laser therapy in twin-to-twin transfusion syndrome (TTTS). We extended our mathematical model of TTTS by adding the dynamics of hematocrit, and simulated incomplete laser therapy, first, by leaving one patent opposite arteriovenous anastomosis from the recipient to the donor and, second, by leaving one patent arteriovenous anastomosis from the donor to the recipient. In both simulations we reproduced the clinical observation of severe hematocrit discordance preceding delayed amniotic fluid imbalance. In conclusion, incomplete laser therapy may cause a severe circulatory imbalance between the twins which presents predominantly as discordant hematocrits rather than discordant amniotic fluid volumes as in primary TTTS. These results imply that the anemia-polycythemia sequence is a sensitive mechanism to identify transfusion reversal after complicated laser therapy, confirming the suggested role of middle cerebral artery peak systolic velocity Doppler measurements as a useful method of follow-up.

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.