Severe twin-twin transfusion syndrome: current management concepts

The Effect of Treatment of Twin-Twin Transfusion Syndrome on the Diagnosis-to-Delivery Interval

No randomised controlled trials of treatment of twin-to-twin transfusion syndrome (TTTS) exist. Since severely preterm neonatal survival has increased over time, survival as an outcome measure is confounded by improvements in neonatal care. The diagnosis-to-delivery interval is a measure of success of treatment independent of improvements in neonatal care. We wished to evaluate whether treatment of TTTS is associated with a lengthening of the diagnosis-to-delivery interval. MEDLINE search was performed supplemented by careful reference review. All TTTS series were included where the following information on each patient was available: survival, fetal demise, gestational age at diagnosis and diagnosis-to-delivery interval in days. Inclusion criteria: gestational age at diagnosis < 29 weeks and diagnosis by ultrasound in the absence of maternal symptoms. Cases undergoing multiple types of treatment were excluded. Eight publications met inclusion criteria and included the following cases: controls (n = 16), amnioreduction (n = 61), septostomy (n = 12), and fetoscopic laser occlusion of chorioangiopagus vessels (n = 51). There was no difference in the diagnosis-to-delivery interval, overall survival, at least one survivor, or number of fetal deaths between the four groups. Logistic regression using at least one survivor as the dependent variable revealed a positive association with gestational age at diagnosis and with diagno-sis-to-delivery interval, a negative correlation with fetal death, and no correlation with treatment group. We conclude that there is no difference in diagnosis-to-delivery interval or survival for any treatment for TTTS compared to expectant management. The lack of significance appears to be due to small sample sizes.

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.

Rapid and radical amniodrainage in the treatment of severe twin-twin transfusion syndrome

We have evaluated the role of a rapid and radical method of amniodrainage in the treatment of severe twin-twin transfusion. The outcome of 15 patients with severe twin-twin transfusion for which a amniodrainage was performed by means of a vacuum bottle system was compared with the outcome of 15 patients with a similar condition, matched for gestational age at the time of the initial procedure and drained using a standard procedure. In the study group the amniodrainage ended when no amniotic fluid could be aspirated, whereas the women in the standard group were drained with a syringe system and the fluid was removed until the deepest amniotic fluid pool was <8 cm. At the initial procedure, the mean volume of amniotic fluid drained was significantly (p<0.05) higher (3252 vs 2153 ml) and the length of the procedure significantly (p<0.001) shorter (21 vs 41 min) in the study group than in the standard group. The mean post-procedure amniotic fluid index was significantly (p<0.001) smaller (2.9 vs 7.7 cm) after radical amniodrainage than after the standard amniodrainage. The mean number of procedures was significantly (p<0.001) lower (1.5 vs 5.6) in the study group compared to the standard group. In the study group the mean placental thickness increased significantly (p<0.001) from 9 mm before the procedure to 49 mm after, and the overall perinatal survival rate was 80% and the proportion of pregnancies with at least one survivor was 93%. The present data indicate that early, rapid and radical amniodrainage is an effective and low-cost therapy for severe twin-twin transfusion syndrome. Compared to the standard amniodrainage technique it also appears to reduce the need for multiple procedures.

Twin-twin transfusion syndrome: etiology, severity and rational management

The twin-twin transfusion syndrome is a serious complication of monochorionic twin pregnancies. Partly as a result of an inadequate understanding of the pathophysiology of the syndrome, there is a lack of consensus in clinical management. We sought to review the available information on the etiology of twin-twin transfusion syndrome, to identify parameters that contribute to the severity of the syndrome, and propose a rational management plan based on pathophysiology, clinical presentation and the efficacy of therapies. We therefore amalgamated recent advances in twin-twin transfusion syndrome computer modelling and clinical studies, particularly on therapeutic outcomes. We found that the oligo-polyhydramnios sequence that defines twin-twin transfusion syndrome prenatally represents a wide continuum of severity in the imbalance between the fetoplacental circulations of both twins. In severe twin-twin transfusion syndrome cases, in which the circulatory imbalance deteriorates beyond fetal control, fetoscopic laser therapy of all anastomoses along the placental vascular equator is predicted to have significantly better survival rates and fewer neurological sequelae than amnioreduction. In contrast, mild twin-twin transfusion syndrome cases have better outcomes after one or at most a few amnioreductions than laser therapy, as a result of significantly fewer procedure-related risks. In conclusion, optimal individual therapy may possibly achieve an 85% survival rate in twin-twin transfusion syndrome, but requires advancement in non-invasive criteria that predict the severity of the syndrome. Identifying such criteria is a future challenge. For the interim, twin-twin transfusion syndrome diagnosed before 26 weeks' gestation has significantly better survival rates and fewer neurological sequelae after laser therapy than amnioreduction. Twin-twin transfusion syndrome diagnosed after 26 weeks can best be treated by amnioreduction, or delivery. Contrary to previous claims, fetoscopic laser therapy has outgrown its experimental status. Although improvements in technique and technology are likely, laser placental ablation has a firm scientific and clinical basis.

Twin-twin transfusion syndrome: the challenge of etiology-based management decisions

Studies published in the past year have attempted to model the pathophysiology of the twin-twin transfusion syndrome and also to establish the minimal diagnostic criteria for the condition. Many papers focused on treatment regimens and their sequelae. Aggressive treatment with serial amnioreduction continues to predominate, and appears to be more successful than conservative medical management, whereas selective feticide is reserved for cases that fail to respond to amnioreduction. Small series utilizing laser ablation and amniotic septostomy appeared; with laser proponents suggesting that their approach may carry a lower risk of neurological sequelae. Progress in ultrasound and Doppler techniques has begun to yield earlier and better diagnostic approaches which, coupled with an awareness of the possible anastomotic configurations, may allow for the selection of the management protocol most likely to succeed in each individual case.

Placental anatomy, fetal demise and therapeutic intervention in monochorionic twins and the transfusion syndrome: new hypotheses

OBJECTIVE

Monochorionic twins with circulatory sharing have an incompletely understood response to acute hemodynamic events. We relate placental vascular anatomy with, first, the response to (a) acute fetal demise and (b) laser interrupted placental anastomoses and, second, the efficacy of current and possibly future therapeutic interventions in twin-twin transfusion syndrome.

DESIGN

Hemodynamic response to acute fetal demise and laser interrupted anastomoses is analysed using the model previously developed for monochorionic twins. Efficacy of therapeutic interventions in twin-twin transfusion syndrome is analysed by combining the estimated incidence of placental anastomotic patterns with three previously proposed pathophysiologic mechanisms.

RESULTS

Fetal demise may cause sequelae for the co-twin in all anastomotic patterns except unidirectional arteriovenous and single venovenous anastomoses which are predicted to be hemodynamically harmless. In twin-twin transfusion syndrome, laser interruption of all anastomoses mitigates further transfusion. This is of benefit for the twins in equally but not in unequally shared placentas. Analysis predicts that approximately 75% fetal survival could be achieved interrupting only arteriovenous anastomoses. Amniocentesis may only prolong pregnancies that lack progressively increasing discordance, assuming that placental anastomoses remain patent following polyhydramnios. This proposed mechanism of action predicts current therapeutic efficacy accurately and could explain the significantly higher reported serious morbidity compared with laser (15/81 = 19+/-5% versus 4/146=3%, P=0.00004). However, if therapeutic interventions could match the syndrome's individual placental anatomy, the analysis suggests approximately 10-15% laser related mortality (premature rupture of membranes) and <3% severe morbidity could possibly become achievable goals.

CONCLUSION

Our predictions allow clinical testing. This information may contribute to an improved management of monochorionic twins.