22 Review
Management of Complicated Monochorionic Twin Pregnancies
Authors
J. Degenhardt1, C. Enzensberger2, A. Tenzer1, A. Kawecki1, T Kohl3, R. Axt-Fliedner1, 2
Affiliations
1
Department of OB/GYN, Division of Prenatal Medicine, Justus-Liebig University and UKGM, Campus Giessen, Giessen, Germany 2 Department of OB/GYN, Division of Prenatal Medicine, UKGM, Campus Marburg, Marburg, Germany 3 German Center for Fetal Surgery & Minimally Invasive Therapy (DZFT), Justus-Liebig University, Giessen, Germany
Key words ▶ Monochorionic twins ● ▶ twin-to-twin transfusion ● syndrome ▶ TRAP ●
Abstract
Zusammenfassung
Multiple gestation is associated with an increased risk for adverse pregnancy outcome. Monochorionic twins are at risk for complications specific to these pregnancies, such as twin-twin transfusion syndrome (TTTS) or twin reverse arterial perfusion (TRAP) sequence. In this article we give an overview on prenatal diagnosis, treatment and outcome of twin pregnancies complicated by TTTS and TRAP sequence.
Mehrlingsschwangerschaften im allgemeinen gehen mit einem erhöhten Risiko prä- und perinataler Komplikationen einher. Bei monochorialen Zwillingen besteht darüber hinaus das Risiko für die Entwicklung spezifischer Probleme wie eines feto-fetalen Transfusionssyndroms (FFTS) oder der Twin-Reverse-Arterial-Perfusion (TRAP) –Sequenz. Im vorliegenden Artikel geben wir einen Überblick über pränatale Diagnose, Behandlungsmöglichkeiten und postnatales Outcome von monochorialen Zwillingen mit FFTS oder TRAP-Sequenz.
Introduction
In the first section of this article we give an overview on prenatal diagnosis, treatment algorithms and outcome of twin pregnancies complicated by TTTS. In the second section we focus on TRAP sequence.
Schlüsselwörter ▶ Monochoriale Zwillinge ● ▶ feto-fetales Transfusions● syndrom ▶ TRAP ●
Bibliography DOI http://dx.doi.org/ 10.1055/s-0034-1382002 Z Geburtsh Neonatol 2015; 219: 22–27 © Georg Thieme Verlag KG Stuttgart · New York ISSN 0948-2393 Correspondence Dr. med. Jan Degenhardt Abteilung für Pränatalmedizin und gynäkologische Sonografie Universitäts-Frauenklinik Justus-Liebig-Universität Giessen Universitätsklinikum Giessen und Marburg GmbH Campus Giessen Klinikstraße 33 35392 Giessen Germany Tel.: + 49-6421-58-66214 Fax: + 49-6421-58-66413 [email protected]
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Multiple gestation is associated with an increased risk for adverse pregnancy outcome. Beside obstetrical complications like preterm delivery caused by preterm rupture of membranes or spontaneous labor higher rates of congenital anomalies and fetal growth retardation influence the perinatal outcome in both monochorionic and dichorionic twin pregnancies. Monochorionic multiple gestations have a higher rate for pregnancy complications than dichorionic twins. Monochorionic twins are monozygotic with both fetuses sharing one placenta. The vascular architecture in these placentas reveals anastomoses in almost every case. The anastomoses can be arterio-venous (AV), veno-arterial (VA), arterio-arterial (AA) or veno-venous (VV). Usually the blood flow in the anastomoses is balanced. Imbalance in this vascular system can lead to specific complications of monochorionic twins such as twin-to-twin transfusion syndrome (TTTS), twin anemia-polycythemia sequence (TAPS), or twin reversed arterial perfusion sequence (TRAP)
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Twin-to-Twin Transfusion Syndrome (TTTS)
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Pathophysiology TTTS is one of the most serious complications of monochorionic twin gestations. It affects 10–15 % of all monochorionic twins and is associated with prenatal untreated high mortality rates and high rates of adverse neurological outcome in surviving fetuses [1, 2]. The clinical appearance of TTTS is heterogeneous with variations in both severity and gestational age at manifestation. Placental intertwin vascular anastomoses are essential in the pathophysiology of TTTS. AV/VA anastomoses are found in 90–95 % of monochorionic placentas, AA in 85–90 %, and VV in 15–20 % [3]. AV and VA anastomoses consist of vessels on
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Management komplizierter monochorialer Zwillingsschwangerschaften
Review 23
Table 1 Quintero staging. Stage
Finding
I II III
Oligohydramnios and polyhydramnios sequence No visible bladder in the donor twin Doppler abnormality (absent/reversed end-diastolic velocity in the umbilical artery, reversed flow in a-wave of the ductus venosus, or pulsatile flow in the umbilical vein in either fetus) (● ▶ Fig. 4) ▶ Fig. 5) One or both fetuses with ascites or hydrops (● Demise of either fetus
IV V
PA = pulmonary artery; Ao = aorta; AEDF = absent end diastolic flow; REDF = reverse end diastolic flow; UA = umbilical artery
Table 2 Children’s Hospital of Philadelphia (CHOP) cardiovascular score. Recipi-
0
1
2
3
ent twin Ventricular characteristics Valve function
Venous Doppler Great vessel analysis Donor twin UA Doppler
Dilatation Hypertrophy Systolic dysfunction
None None None
Mild Mild Mild
Tricuspid regurgitation Mitral regurgitation Tricuspid inflow Mitral inflow Ductus venosus flow Umbilical vein flow
None None 2 peaks 2 peaks Forward No pulsation PA > Ao
Mild > Mild Mild > Mild 1 peak 1 peak Notching Reversal Pulsation
Normal
Decrease AEDF
PA vs. Ao size
PA = Ao
> Mild > Mild > Mild
PA < Ao
REDF
Diagnosis and clinical management of monochorionic twin gestations The diagnosis of TTTS is made by ultrasound either in asymptomatic patients in routine scans or because of symptomatic polyhydramnios causing uterine distention or labor. The diagnosis is based on an imbalance of amniontic fluid with polyhydramnios ▶ Fig. 3) and oligohydramnios in the donor in the recipient (● fetus. In cases with severe oligo- or anhydramnios the donor fetus may appear “stuck” to the uterine wall. Quintero developed a standardized staging system to describe severity and progression of TTTS [10]. In stage I the twins present with oligohydramnios/polyhydramnios sequence, in stage II the bladder in the donor fetus is no longer visible, stage III adds Doppler abnormality consisting of absent or reverse flow in the umbilical artery, reverse flow in the ductus venosus or pulsatile flow in the umbilical vein. In stage IV either fetus has ascites or hydrops and in stage V one or both fetuses has died ▶ Table 1). This classification has limitations as it implies an (● orderly progression of stages which is not the case. In addition, the Quintero system omits detailed description of cardiovascular changes in the fetuses. Rychik et al. developed a classification ▶ Table 2). system that incorporates cardiovascular changes (● As 10–15 % of monochorionic pregnancies develop TTTS [11] intensive monitoring is important. Essential for appropriate sur-
Fig. 1 T-sign.
veillance of twin gestations is the exact determination of chorionicity in the first trimester. This is easily possible by ▶ Fig. 1) which reflects a thin visualization of the “T-sign” (● membrane formed by the apposition of the 2 amnion layers approaching the placenta in an approximately 90 ° angle. In contrast, dichorionic gestation presents with a thicker inter-twin membrane formed by 2 thin amniotic membranes with a thick ▶ Fig. 2). layer of chorion in between (“Lambda sign”, ●
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the surface of the chorionic plate that descend into a common cotyledon capillary network where they anastomose. AA and VV anastomoses are direct superficial connections on the surface of the placenta with the potential for bidirectional flow. AV/VA anastomoses allow only unidirectional flow but are usually multiple and overall balanced in both directions. It has been suggested that imbalance of the number of AV/VA anastomoses without compensating AA anastomoses leads to the clinical appearance of TTTS [4]. The shift of blood flow leads to hypovolemia, oliguria and oligo-anhydramnios in the so-called donor twin. In contrast, the recipient twin presents with hypervolemia, polyuria and polyhydramnios. Triggered by the relative hypovolemia the donor’s renin–angiotensin system (RAS) is activated to restore the circulating volume. Angiotensin II leads to vasoconstriction and stimulates the release of aldosterone which leads to sodium and water retention [5]. As a result blood pressure increases in the donor twin. In the recipient twin, the imbalance of intertwin transfusion causes hypervolemia leading to the release of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) by an increased atrial preload [6]. As a response, diuresis and urine output are enhanced resulting in the clinical appearance of severe polyhydramnios. Hypervolemia and abnormal concentrations of vasoactive mediators have consequences for the cardiovascular system and lead to cardiac hypertrophy, cardiomegaly, atrioventricular valve regurgitation and increased outflow-tract peak velocities reflecting hyperdynamic circulation [7, 8]. Myocardial dysfunction predominantly affects the right ventricle [9]. Myocardial hypertrophy can finally lead to ▶ Fig. 6). functional pulmonal obstruction (● Differential diagnoses for TTTS in discordant monochorionic twins include selective intrauterine growth restriction (s-IUGR) caused by unequal placental sharing, uteroplacental dysfunction, and congenital anomalies. In these cases parental counselling should include the option for selective fetocide to improve the outcome of the healthy twin. This is beyond the scope of this manuscript.
Fig. 2 Lambda sign.
Fig. 3 Monochorionic twins with TTTS stage II. Note the polyhydramnios and the filled bladder in the recipient.
Fig. 5 Pleural effusion in a recipient fetus in TTTS stage IV.
Fig. 6 3 vessel view in a fetus with TTTS Quintero IV. Note the reverse flow in the pulmonary trunc (red colour) indicating functional pulmonal stenosis.
Attempts have been made to stratify the risk for developing TTTS in monochorionic twins in first trimester by ultrasound. Discrepant nuchal translucency (NT) measurements turned out not to be a good predictor for TTTS [12]. A discrepancy in crownrump length or discordant amniotic fluid are significant predictors for developing TTTS [12]. If such a discrepancy is detected surveillance intervals should be weekly in order to detect early TTTS. In monochorionic gestations, we recommend ultrasound examination weekly, beginning at 16 weeks of gestation and continuing until 24 weeks as most TTTS occur in this period. From 24–28 weeks we recommend examinations every 2 weeks. Examinations include assessment of amniotic fluid volume, fetal bladder visualization, feto-maternal Doppler and fetal growth (every 2 weeks). In the third trimester we advice weekly followup for detection of TAPS. Fig. 4 Reversed a-wave in the ductus venosus of the recipient fetus in TTTS stage III.
Management of twin-to-twin transfusion syndrome Theoretically management options for TTTS include expectant management, amnioreduction, septostomy fetoscopic laser ablation of placental anastomoses, and selective fetocide.
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24 Review
Due to the poor outcomes and low survival rates expectant management of TTTS is not recommended in Quintero stage II and higher. In stage I management regimes are still controversial because there are only few data focused specifically on the outcome of TTTS stage I. It is known that TTTS stage I can remain at this stage or even regress [13]. On the contrary, intervention may be associated with an improvement in long-term neurodevelopmental outcome in fetuses at TTTS stage I treated by laser ablation compared to those with expectant management [14] and improved perinatal survival [15]. Amnioreduction to remove excess amniotic fluid in the recipients amniotic cavity, either performed as one-time procedure or serially, results in higher survival rates than expectant management by decreasing the risk for preterm premature rupture of membranes (PPROM) and preterm labor. It may also reduce the intraamniotic and placental intravascular pressures, which improves placental blood flow. On the downside, serial amnioreduction increases the likelihood of complications such as PPROM, preterm labor, placental abruption, infection, and fetal death [16]. In a review of the literature including only TTTS stage I, the overall survival rates were 86 % after expectant management, 77 % after amnioreduction, and 86 % after laser therapy. The authors conclude that expectant management in TTTS stage I is legitimate [17]. At our center we prefer ultrasound surveillance over amnioreduction in mild cases but offer laser ablation as a definitive treatment in cases of stage I if the patient has symptomatic polyhydramnios, labor or shortening of the cervix to reduce the risk for abortion and loss of both fetuses. Fetoscopic laser ablation of placental anastomoses was introduced by De Lia in 1990 [18] and is recommended as a definitive treatment of the Quintero stages II–IV TTTS under 26 weeks of gestation. Senat et al. published data from a randomized clinical trial that evaluated outcomes after laser ablation vs. amnioreduction in 142 women with second trimester severe TTTS [19]. The group that underwent laser therapy had a significantly higher mean gestational age at delivery (33 vs. 29 weeks), higher survival of at least one fetus to 28 days of age (76 % vs. 56 %) and a significantly lower incidence of periventricular leukomalacia at six months of age (6 vs. 14 %). Furthermore, survivors were significantly more likely to be free of neurological complications at 6 months of age (52 vs. 31 %). These results were confirmed by a meta-analysis of studies that found fetuses undergoing laser ablation were twice as likely to survive and had an 80 % reduction in neurologic morbidity [20]. A recent study suggests that different treatment modalities may also have a long term impact on cardiac function in these twins [40]. The goal of laser ablation is “dichorionization” which is to functionally separate the monochorionic placenta into 2 regions, each supplying one of the fetuses. The procedure is performed under intravenous analgesia and local anesthesia. General anesthesia is usually not required. A 5 mm trocar is placed in the recipient’s amniotic sac in a Seldinger technique under ultrasound guidance. A 2 mm fetoscope is inserted and the placental equatorial plate between the 2 cord insertions is visualized. A laser fiber is inserted via the operating channel of the endoscope. At our center we use a diode laser that provides 50 watts of energy (single pulse). There are different technical approaches to laser ablation. Initially all vessels crossing the inter-twin membrane were ablated. In 2000, Quintero introduced the selective laser photocoagula-
tion (SLPCV). The identification of the placental vascular anastomoses that are to be coagulated led to a lower rate of fetal demise after selective ablation and was associated with improved survival of at least one fetus (83 vs. 61 %) [21]. In 2007, sequential selective laser photocoagulation (SQLPCV) was introduced. In this technique, first AV/VA, and then VV, and AA anastomoses are coagulated in sequential order. The authors hypothesize that this method “would result in an improved hemodynamic status and decreased likelihood of intrauterine fetal demise of the donor twin” [22]. The results seem to support this hypothesis as SQLPCV led to a reduction in the risk of intrauterine demise of both twins compared with selective ablation (40 vs. 50 %) and higher rates of perinatal survival [23]. Finally, the Solomon technique is another method of laser ablation. After an initial SLPCV the entire placental vascular equator on the surface of the placenta is coagulated in a line. In a randomized trial comparing this technique to standard laser coagulation in patients with TTTS II, III or IV the equatorial technique resulted in lower rates of twin anemia polycythemia sequence (TAPS) and recurrence of TTTS (3 vs. 16 % and 1 vs. 7 %, respectively), but no significant difference in perinatal mortality or severe neonatal morbidity [24]. At present a prospective multicenter randomized trial was started to compare selective laser ablation and the Solomon technique (Solomon Study). At our center we currently perform a sequential selective technique. Laser ablation is associated with complications including chorioamnionitis, PPROM, preterm delivery, amniotic fluid leakage, vaginal bleeding, and placental abruption. In the Eurofetus trial, the overall risk for most complications was about 3 % [19]. A complication specific to pregnancies after laser ablation is the persistance of TTTS or development of post-laser TAPS in up to 13 % [25] which is caused by residual AV/VA anastomoses. TAPS is a milder variant of, often reversed, TTTS. The anastomoses lead to a shifting of red blood cells with the recipient becoming anemic and the donor polycythemic. In approximately 25 % of cases, post-laser TAPS can also result in an anemic donor and a polycythemic recipient [26]. For this reason, pregnancies after laser ablation require intensive follow-up with ultrasound and Doppler assessment on a weekly basis to detect TAPS or intrauterine growth restriction (IUGR). TAPS is detectable by Doppler measurements of the middle cerebral artery (MCA). If there is a discordance of peak systolic velocities (> 1.5 MoM) in the donor and < 1.5 MoM in the recipient twin) TAPS is likely. The therapy for TAPS depends on the gestational age at occurrence. Treatment options include (repeat) laser ablation, intrauterine blood transfusion to the donor, and delivery [27, 39]. If there is no indication for early delivery, babies should be delivered at 37 weeks of gestation because the risk for fetal demise increases overproportionally.
Twin Reversed Arterial Perfusion (TRAP) Sequence
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With an incidence of about 1 % of monochorionic twin pregnancies and 1 in 35 000 deliveries [28] twin reversed arterial perfusion sequence (TRAP) is a rare, unique complication of monochorionic twin pregnancy in which a twin with an absent or a non-functioning heart (“acardiac twin”) is perfused by its co-twin (“pump twin”) via placental arterial anastomoses. As the acardiac twin has no own placental circulation his blood supply is dependent from the pump twin´s circulation. His deoxygenated blood is shunted to the acardiac twin via AA anasto-
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Review 25
26 Review
Conclusion
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For monochorionic twin gestations complicated by TTTS or TRAP sequence minimally invasive procedures can be offered to improve survival and outcome of affected fetuses. These procedures cause little trauma to the expectant mothers but PPROM following endoscopic treatment is still challenging. Patients
should be counselled interdisciplinary by prenatal medicine specialists and neonatologists to support individual decision making. Still unclear is the optimal treatment regime for stage I TTTS. Further randomized trials are needed here.
Interessenkonflikt: Die Autoren geben an, dass kein Interessenkonflikt besteht. References 1 Berghella V, Kaufmann M. Natural history of twin-twin transfusion syndrome. J Reprod Med 2001; 46: 480–483 2 Lewi L, Jani J, Blickstein I et al. The outcome of monochorionic diamniotic twin gestations in the era of invasive fetal therapy: a prospective cohort study. Am J Obstet Gynecol 2008; 199: 514–518 3 De Paepe ME, Shapiro S, Greco D et al. Placental markers of twinto-twin transfusion syndrome in diamniotic-monochorionic twins: a morphometric analysis of deep artery-to-vein anastomoses. Placenta 2010; 31: 269–276 4 Denbow ML, Cox P, Taylor M et al. Placental angioarchitecture in monochorionic twin pregnancies: relationship to fetal growth, fetofetal transfusion syndrome and pregnancy outcome. Am J Obstet Gynecol 2000; 182: 417–426 5 Mahieu-Caputo D, Dommergues M, Delezoide AL et al. Twin-to-twin transfusion syndrome. Role of the fetal renin-angiotensin system. Am J Pathol 2000; 156: 629 6 Bajoria R, Ward S, Chatterjee R. Natriuretic peptides in the pathogenesis of cardiac dysfunction in the recipient fetus of twin-twin transfusion syndrome. Am J Obstet Gynecol 2002; 186: 121 7 Karatza AA, Wolfenden JL, Taylor MJ et al. Influence of twin-twin transfusion syndrome on fetal cardiovascular structure and function: prospective case-control study of 136 monochorionic twin pregnancies. Heart 2002; 88: 271 8 Simpson LL, Marx GR, Elkadry EA et al. Cardiac dysfunction in twintwin transfusion syndrome: a prospective, longitudinal study. Obstet Gynecol 1998; 92: 557 9 Barrea C, Alkazaleh F, Ryan G et al. Prenatal cardiovascular manifestations in the twin-to-twin transfusion syndrome recipients and the impact of therapeutic amnioreduction. Am J Obstet Gynecol 2005; 192: 892 10 Quintero RA, Morales WJ, Allen MH et al. Staging of twin-twin transfusion syndrome. J Perinatol 1999; 19: 550 11 Lewi L, Jani J, Boes AS et al. The natural history of monochorionic twins and the role of prenatal ultrasound scan. Ultrasound Obstet Gynecol 2007; 30: 401 12 Lewi L, Lewi P, Diemert A et al. The role of ultra-sound examination in the first trimester and at 16 weeks’ gestation to predict fetal complications in monochorionic diamniotic twin pregnancies. Am J Obstet Gynecol 2008; 199: e1–e7 13 Dickinson JE, Evans S. The progression of disease stage in twin–twin transfusion syndrome. J Matern Fetal Neonatal Med 2004; 16: 95–101 14 Wagner MM, Lopriore E, Klumper FJ et al. Short- and long-term outcome in stage 1 twin-to-twin transfusion syndrome treated with laser surgery compared with conservative management. Am J Obstet Gynecol 2009; 201: 286 e1 15 Middeldorp JM, Sueters M, Lopriore E et al. Fetoscopic laser surgery in 100 pregnancies with severe twin-to-twin transfusion syndrome in the Netherlands. Fetal Diagn Ther 2007; 22: 190–194 16 Roberts D, Gates S, Kilby M et al. Interventions for twin-twin transfusion syndrome: a Cochrane review. Ultrasound Obstet Gynecol 2008; 31: 701–711 17 Rossi C, D’Addario V. Survival outcomes of twin-twin transfusion syndrome in stage I: a systematic review of the literature. Am J Perinatol 2013 Jan; 30: 5–10 18 De Lia JE, Cruikshank DP, Keye WR Jr. Fetoscopic neodymium:YAG laser occlusion of placental vessels in severe twin-twin transfusion syndrome. Obstet Gynecol 1990; 75: 1046 19 Senat MV, Deprest J, Boulvain M et al. Endoscopic laser surgery versus serial amnioreduction for severe twin-to-twin transfusion syndrome. N Engl J Med 2004; 351: 136 20 Rossi AC, D’Addario V. Laser therapy and serial amnioreduction as treatment for twin-twin transfusion syndrome: a metaanalysis and review of literature. Am J Obstet Gynecol 2008; 198: 147 21 Quintero RA, Comas C, Bornick PW et al. Selective versus non-selective laser photocoagulation of placental vessels in twin-to-twin transfusion syndrome. Ultrasound Obstet Gynecol 2000; 16: 230
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mosis to the lower half of the recipient twin via its iliac arteries. Perfusion of the upper torso and head is poor. Blood supply is barely sufficient to maintain metabolic activity and leads to hypoxic damage to developing tissues. The selective perfusion of the lower body causes various structural abnormalities in the acardiac twin [29]. Umbilical-venous return of further deoxygenated blood to the pump twin is conditioned by VV anastomoses, so the blood administration to the pump twin includes oxygenated blood from the placenta and deoxygenated blood from the acardiac twin. This may lead to chronic hypoxia and growth restriction in the pump twin and has also effects on the pump twins cardiovascular system [30]. Volume preload as well as pump afterload increase. Therefore, the pump twin may develop high-output cardiac failure including polyhydramnios, cardiomegaly, tricuspid regurgitation, pleural effusions, ascites, and hydrops fetalis. The development of cardiac failure depends on the size of the acardiac twin. Given a ratio of the acardiac twin to that of the pump twin of more than 0.70 the risk of heart failure increases from 10–30 % [31]. These criteria are associated with poor outcome. If TRAP is suspected diagnosis is confirmed by Doppler ultrasound revealing arterial blood flow towards the acardiac twin in its umbilical arteries. Mortality rates of 55 % for untreated TRAP have been reported [32]. In cases with one or more poor prognostic criteria, intrauterine intervention or delivery, depending on the gestational age, should be considered. Treatment options are laser ablation, bipolar cord coagulation, radiofrequency ablation (RFA), and fetoscopic cord ligation [33–35]. Laser ablation is performed with the patient under local anesthesia and access to the acardiac sac is achieved analogously to laser ablation for TTTS. The umbilical cord is visualized and coagulated near the placental insertion site. If the umbilical cord is too thick for complete coagulation the goal of cord occlusion is achievable by using a bipolar cautery forceps. Laser ablation in TRAP can also be performed as intrafetal laser ablation [36]. At our center we prefer RFA over laser ablation in pregnancies of more than 16 weeks of gestation. A radio frequency (at our center 17-gauge with a 2 cm umbrella) needle is inserted into the amniotic cavity of the acardiac twin under ultrasound guidance in local anesthesia. The abdominal wall at the base of the umbilical cord is targeted and the tines are deployed within the abdomen. The emitted energy is initially 10 watts and increased stepwise until the specific impedance is reached. Success of the operation is documented by the absence of flow from the pump twin to the acardiac twin in Doppler ultrasound. The outcome data of both techniques is comparable with survival rates of 80–90 % [37, 38]. Both techniques are safe for the mothers. Possible complications are uncommon and the same as in other invasive procedures such as chorioamnionitis, PPROM, preterm delivery, amniotic fluid leakage, vaginal bleeding, and placental abruption. A recent meta-analysis reported significantly lower rates of adverse pregnancy outcome when the treatment was performed before 16 weeks of gestation [37].
22 Quintero RA, Ishii K, Chmait RH et al. Sequential selective laser photocoagulation of communicating vessels in twin-twin transfusion syndrome. J Matern Fetal Neonatal Med 2007; 20: 763–768 23 Chmait RH, Kontopoulos EV, Korst LM et al. Stage-based outcomes of 682 consecutive cases of twin-twin transfusion syndrome treated with laser surgery: the USFetus experience. Am J Obstet Gynecol 2011; 204: 393 e1 24 Slaghekke F, Lopriore E, Lewi L et al. Fetoscopic laser coagulation of the vascular equator versus selective coagulation for twin-totwin transfusion syndrome: an open-label randomised controlled trial. Lancet 2014; pii: S0140-6736(13)62419-8 doi:10.1016/S01406736(13)62419-8 [Epub ahead of print] 25 Lopriore E, Slaghekke F, Middeldorp JM et al. Residual anastomoses in twin-to-twin transfusion syndrome treated with selective fetoscopic laser surgery: localization, size, and consequences. Am J Obstet Gynecol 2009; 201: 66 e1 26 Slaghekke F, Kist WJ, Oepkes D et al. Twin anemia-polycythemia sequence: diagnostic criteria, classification, perinatal management and outcome. Fetal Diagn Ther 2010; 27: 181 27 Lopriore E, Hecher K, Vandenbussche FP et al. Fetoscopic laser treatment of twin-to-twin transfusion syndrome followed by severe twin anemia-polycythemia sequence with spontaneous resolution. Am J Obstet Gynecol 2008; 199: 493 e1–493 e7 28 Moore TR, Gale S, Benirschke K. Perinatal outcome of forty-nine pregnancies complicated by acardiac twinning. Am J Obstet Gynecol 1990; 163: 907–912 29 Van Allen MI, Smith DW, Shepard TH. Twin reversed arterial perfusion (TRAP) sequence: a study of 14 twin pregnancies with acardius. Semin Perinatol 1983; 7: 285 30 Van Gemert MJC, Umur A, van den Wijngaard JPHM et al. Increasing cardiac output and decreasing oxygenation sequence in pump twins of acardiac twin pregnancies. Phys Med Biol 2005; 50: N33–42
31 Moore TR, Gale S, Benirschke K. Perinatal outcome of forty-nine pregnancies complicated by acardiac twinning. Am J Obstet Gynecol 1990; 163: 907 32 Lewi L, Valencia C, Gonzalez E et al. The outcome of twin reversed arterial perfusion sequence diagnosed in the first trimester. Am J Obstet Gynecol 2010; 203 (213): e1–e4 33 Ville Y, Hyett JA, Vandenbussche FP et al. Endoscopic laser coagulation of umbilical cord vessels in twin reversed arterial perfusion sequence. Ultrasound Obstet Gynecol 1994; 4: 396 34 Lee H, Wagner AJ, Sy E et al. Efficacy of radiofrequency ablation for twin-reversed arterial perfusion sequence. Am J Obstet Gynecol 2007; 197: 459 35 Deprest JA, Audibert F, Van Schoubroeck D et al. Bipolar coagulation of the umbilical cord in complicated monochorionic twin pregnancy. Am J Obstet Gynecol 2006; 28: 688 36 Jolly M, Taylor M, Rose G et al. Interstitial laser: a new surgical technique for twin reversed arterial perfusion sequence in early pregnancy. BJOG 2001; 108: 1098–1102 37 Pagani G, D’Antonio F, Khalil A et al. Intrafetal laser treatment for twin reversed arterial perfusion sequence: cohort study and meta-analysis. Ultrasound Obstet Gynecol 2013; 42: 6 38 Cabassa P, Fichera A, Prefumo F et al. The use of radiofrequency in the treatment of twin reversed arterial perfusion sequence: a case series and review of the literature. Eur J Obstet Gynecol Reprod Biol 2013; 166: 127 39 Diehl W, Glosemeyer P, Tavares De Sousa M et al. Twin anemia-polycythemia sequence in a case of monoamniotic twins. Ultrasound Obstet Gynecol 2013; 42: 108–111 40 Gardiner HM, Matsui H, Roughton M et al. Cardiac function in 10-yearold twins following differetn fetal therapies for twin-twin transfusion syndrome. Ultrasound Obestet Gynecol 2014; 43: 652–657
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Review 27
Management of Complicated Monochorionic Twin Pregnancies
Authors
J. Degenhardt1, C. Enzensberger2, A. Tenzer1, A. Kawecki1, T Kohl3, R. Axt-Fliedner1, 2
Affiliations
1
Department of OB/GYN, Division of Prenatal Medicine, Justus-Liebig University and UKGM, Campus Giessen, Giessen, Germany 2 Department of OB/GYN, Division of Prenatal Medicine, UKGM, Campus Marburg, Marburg, Germany 3 German Center for Fetal Surgery & Minimally Invasive Therapy (DZFT), Justus-Liebig University, Giessen, Germany
Key words ▶ Monochorionic twins ● ▶ twin-to-twin transfusion ● syndrome ▶ TRAP ●
Abstract
Zusammenfassung
Multiple gestation is associated with an increased risk for adverse pregnancy outcome. Monochorionic twins are at risk for complications specific to these pregnancies, such as twin-twin transfusion syndrome (TTTS) or twin reverse arterial perfusion (TRAP) sequence. In this article we give an overview on prenatal diagnosis, treatment and outcome of twin pregnancies complicated by TTTS and TRAP sequence.
Mehrlingsschwangerschaften im allgemeinen gehen mit einem erhöhten Risiko prä- und perinataler Komplikationen einher. Bei monochorialen Zwillingen besteht darüber hinaus das Risiko für die Entwicklung spezifischer Probleme wie eines feto-fetalen Transfusionssyndroms (FFTS) oder der Twin-Reverse-Arterial-Perfusion (TRAP) –Sequenz. Im vorliegenden Artikel geben wir einen Überblick über pränatale Diagnose, Behandlungsmöglichkeiten und postnatales Outcome von monochorialen Zwillingen mit FFTS oder TRAP-Sequenz.
Introduction
In the first section of this article we give an overview on prenatal diagnosis, treatment algorithms and outcome of twin pregnancies complicated by TTTS. In the second section we focus on TRAP sequence.
Schlüsselwörter ▶ Monochoriale Zwillinge ● ▶ feto-fetales Transfusions● syndrom ▶ TRAP ●
Bibliography DOI http://dx.doi.org/ 10.1055/s-0034-1382002 Z Geburtsh Neonatol 2015; 219: 22–27 © Georg Thieme Verlag KG Stuttgart · New York ISSN 0948-2393 Correspondence Dr. med. Jan Degenhardt Abteilung für Pränatalmedizin und gynäkologische Sonografie Universitäts-Frauenklinik Justus-Liebig-Universität Giessen Universitätsklinikum Giessen und Marburg GmbH Campus Giessen Klinikstraße 33 35392 Giessen Germany Tel.: + 49-6421-58-66214 Fax: + 49-6421-58-66413 [email protected]
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Multiple gestation is associated with an increased risk for adverse pregnancy outcome. Beside obstetrical complications like preterm delivery caused by preterm rupture of membranes or spontaneous labor higher rates of congenital anomalies and fetal growth retardation influence the perinatal outcome in both monochorionic and dichorionic twin pregnancies. Monochorionic multiple gestations have a higher rate for pregnancy complications than dichorionic twins. Monochorionic twins are monozygotic with both fetuses sharing one placenta. The vascular architecture in these placentas reveals anastomoses in almost every case. The anastomoses can be arterio-venous (AV), veno-arterial (VA), arterio-arterial (AA) or veno-venous (VV). Usually the blood flow in the anastomoses is balanced. Imbalance in this vascular system can lead to specific complications of monochorionic twins such as twin-to-twin transfusion syndrome (TTTS), twin anemia-polycythemia sequence (TAPS), or twin reversed arterial perfusion sequence (TRAP)
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Twin-to-Twin Transfusion Syndrome (TTTS)
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Pathophysiology TTTS is one of the most serious complications of monochorionic twin gestations. It affects 10–15 % of all monochorionic twins and is associated with prenatal untreated high mortality rates and high rates of adverse neurological outcome in surviving fetuses [1, 2]. The clinical appearance of TTTS is heterogeneous with variations in both severity and gestational age at manifestation. Placental intertwin vascular anastomoses are essential in the pathophysiology of TTTS. AV/VA anastomoses are found in 90–95 % of monochorionic placentas, AA in 85–90 %, and VV in 15–20 % [3]. AV and VA anastomoses consist of vessels on
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Management komplizierter monochorialer Zwillingsschwangerschaften
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Table 1 Quintero staging. Stage
Finding
I II III
Oligohydramnios and polyhydramnios sequence No visible bladder in the donor twin Doppler abnormality (absent/reversed end-diastolic velocity in the umbilical artery, reversed flow in a-wave of the ductus venosus, or pulsatile flow in the umbilical vein in either fetus) (● ▶ Fig. 4) ▶ Fig. 5) One or both fetuses with ascites or hydrops (● Demise of either fetus
IV V
PA = pulmonary artery; Ao = aorta; AEDF = absent end diastolic flow; REDF = reverse end diastolic flow; UA = umbilical artery
Table 2 Children’s Hospital of Philadelphia (CHOP) cardiovascular score. Recipi-
0
1
2
3
ent twin Ventricular characteristics Valve function
Venous Doppler Great vessel analysis Donor twin UA Doppler
Dilatation Hypertrophy Systolic dysfunction
None None None
Mild Mild Mild
Tricuspid regurgitation Mitral regurgitation Tricuspid inflow Mitral inflow Ductus venosus flow Umbilical vein flow
None None 2 peaks 2 peaks Forward No pulsation PA > Ao
Mild > Mild Mild > Mild 1 peak 1 peak Notching Reversal Pulsation
Normal
Decrease AEDF
PA vs. Ao size
PA = Ao
> Mild > Mild > Mild
PA < Ao
REDF
Diagnosis and clinical management of monochorionic twin gestations The diagnosis of TTTS is made by ultrasound either in asymptomatic patients in routine scans or because of symptomatic polyhydramnios causing uterine distention or labor. The diagnosis is based on an imbalance of amniontic fluid with polyhydramnios ▶ Fig. 3) and oligohydramnios in the donor in the recipient (● fetus. In cases with severe oligo- or anhydramnios the donor fetus may appear “stuck” to the uterine wall. Quintero developed a standardized staging system to describe severity and progression of TTTS [10]. In stage I the twins present with oligohydramnios/polyhydramnios sequence, in stage II the bladder in the donor fetus is no longer visible, stage III adds Doppler abnormality consisting of absent or reverse flow in the umbilical artery, reverse flow in the ductus venosus or pulsatile flow in the umbilical vein. In stage IV either fetus has ascites or hydrops and in stage V one or both fetuses has died ▶ Table 1). This classification has limitations as it implies an (● orderly progression of stages which is not the case. In addition, the Quintero system omits detailed description of cardiovascular changes in the fetuses. Rychik et al. developed a classification ▶ Table 2). system that incorporates cardiovascular changes (● As 10–15 % of monochorionic pregnancies develop TTTS [11] intensive monitoring is important. Essential for appropriate sur-
Fig. 1 T-sign.
veillance of twin gestations is the exact determination of chorionicity in the first trimester. This is easily possible by ▶ Fig. 1) which reflects a thin visualization of the “T-sign” (● membrane formed by the apposition of the 2 amnion layers approaching the placenta in an approximately 90 ° angle. In contrast, dichorionic gestation presents with a thicker inter-twin membrane formed by 2 thin amniotic membranes with a thick ▶ Fig. 2). layer of chorion in between (“Lambda sign”, ●
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the surface of the chorionic plate that descend into a common cotyledon capillary network where they anastomose. AA and VV anastomoses are direct superficial connections on the surface of the placenta with the potential for bidirectional flow. AV/VA anastomoses allow only unidirectional flow but are usually multiple and overall balanced in both directions. It has been suggested that imbalance of the number of AV/VA anastomoses without compensating AA anastomoses leads to the clinical appearance of TTTS [4]. The shift of blood flow leads to hypovolemia, oliguria and oligo-anhydramnios in the so-called donor twin. In contrast, the recipient twin presents with hypervolemia, polyuria and polyhydramnios. Triggered by the relative hypovolemia the donor’s renin–angiotensin system (RAS) is activated to restore the circulating volume. Angiotensin II leads to vasoconstriction and stimulates the release of aldosterone which leads to sodium and water retention [5]. As a result blood pressure increases in the donor twin. In the recipient twin, the imbalance of intertwin transfusion causes hypervolemia leading to the release of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) by an increased atrial preload [6]. As a response, diuresis and urine output are enhanced resulting in the clinical appearance of severe polyhydramnios. Hypervolemia and abnormal concentrations of vasoactive mediators have consequences for the cardiovascular system and lead to cardiac hypertrophy, cardiomegaly, atrioventricular valve regurgitation and increased outflow-tract peak velocities reflecting hyperdynamic circulation [7, 8]. Myocardial dysfunction predominantly affects the right ventricle [9]. Myocardial hypertrophy can finally lead to ▶ Fig. 6). functional pulmonal obstruction (● Differential diagnoses for TTTS in discordant monochorionic twins include selective intrauterine growth restriction (s-IUGR) caused by unequal placental sharing, uteroplacental dysfunction, and congenital anomalies. In these cases parental counselling should include the option for selective fetocide to improve the outcome of the healthy twin. This is beyond the scope of this manuscript.
Fig. 2 Lambda sign.
Fig. 3 Monochorionic twins with TTTS stage II. Note the polyhydramnios and the filled bladder in the recipient.
Fig. 5 Pleural effusion in a recipient fetus in TTTS stage IV.
Fig. 6 3 vessel view in a fetus with TTTS Quintero IV. Note the reverse flow in the pulmonary trunc (red colour) indicating functional pulmonal stenosis.
Attempts have been made to stratify the risk for developing TTTS in monochorionic twins in first trimester by ultrasound. Discrepant nuchal translucency (NT) measurements turned out not to be a good predictor for TTTS [12]. A discrepancy in crownrump length or discordant amniotic fluid are significant predictors for developing TTTS [12]. If such a discrepancy is detected surveillance intervals should be weekly in order to detect early TTTS. In monochorionic gestations, we recommend ultrasound examination weekly, beginning at 16 weeks of gestation and continuing until 24 weeks as most TTTS occur in this period. From 24–28 weeks we recommend examinations every 2 weeks. Examinations include assessment of amniotic fluid volume, fetal bladder visualization, feto-maternal Doppler and fetal growth (every 2 weeks). In the third trimester we advice weekly followup for detection of TAPS. Fig. 4 Reversed a-wave in the ductus venosus of the recipient fetus in TTTS stage III.
Management of twin-to-twin transfusion syndrome Theoretically management options for TTTS include expectant management, amnioreduction, septostomy fetoscopic laser ablation of placental anastomoses, and selective fetocide.
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24 Review
Due to the poor outcomes and low survival rates expectant management of TTTS is not recommended in Quintero stage II and higher. In stage I management regimes are still controversial because there are only few data focused specifically on the outcome of TTTS stage I. It is known that TTTS stage I can remain at this stage or even regress [13]. On the contrary, intervention may be associated with an improvement in long-term neurodevelopmental outcome in fetuses at TTTS stage I treated by laser ablation compared to those with expectant management [14] and improved perinatal survival [15]. Amnioreduction to remove excess amniotic fluid in the recipients amniotic cavity, either performed as one-time procedure or serially, results in higher survival rates than expectant management by decreasing the risk for preterm premature rupture of membranes (PPROM) and preterm labor. It may also reduce the intraamniotic and placental intravascular pressures, which improves placental blood flow. On the downside, serial amnioreduction increases the likelihood of complications such as PPROM, preterm labor, placental abruption, infection, and fetal death [16]. In a review of the literature including only TTTS stage I, the overall survival rates were 86 % after expectant management, 77 % after amnioreduction, and 86 % after laser therapy. The authors conclude that expectant management in TTTS stage I is legitimate [17]. At our center we prefer ultrasound surveillance over amnioreduction in mild cases but offer laser ablation as a definitive treatment in cases of stage I if the patient has symptomatic polyhydramnios, labor or shortening of the cervix to reduce the risk for abortion and loss of both fetuses. Fetoscopic laser ablation of placental anastomoses was introduced by De Lia in 1990 [18] and is recommended as a definitive treatment of the Quintero stages II–IV TTTS under 26 weeks of gestation. Senat et al. published data from a randomized clinical trial that evaluated outcomes after laser ablation vs. amnioreduction in 142 women with second trimester severe TTTS [19]. The group that underwent laser therapy had a significantly higher mean gestational age at delivery (33 vs. 29 weeks), higher survival of at least one fetus to 28 days of age (76 % vs. 56 %) and a significantly lower incidence of periventricular leukomalacia at six months of age (6 vs. 14 %). Furthermore, survivors were significantly more likely to be free of neurological complications at 6 months of age (52 vs. 31 %). These results were confirmed by a meta-analysis of studies that found fetuses undergoing laser ablation were twice as likely to survive and had an 80 % reduction in neurologic morbidity [20]. A recent study suggests that different treatment modalities may also have a long term impact on cardiac function in these twins [40]. The goal of laser ablation is “dichorionization” which is to functionally separate the monochorionic placenta into 2 regions, each supplying one of the fetuses. The procedure is performed under intravenous analgesia and local anesthesia. General anesthesia is usually not required. A 5 mm trocar is placed in the recipient’s amniotic sac in a Seldinger technique under ultrasound guidance. A 2 mm fetoscope is inserted and the placental equatorial plate between the 2 cord insertions is visualized. A laser fiber is inserted via the operating channel of the endoscope. At our center we use a diode laser that provides 50 watts of energy (single pulse). There are different technical approaches to laser ablation. Initially all vessels crossing the inter-twin membrane were ablated. In 2000, Quintero introduced the selective laser photocoagula-
tion (SLPCV). The identification of the placental vascular anastomoses that are to be coagulated led to a lower rate of fetal demise after selective ablation and was associated with improved survival of at least one fetus (83 vs. 61 %) [21]. In 2007, sequential selective laser photocoagulation (SQLPCV) was introduced. In this technique, first AV/VA, and then VV, and AA anastomoses are coagulated in sequential order. The authors hypothesize that this method “would result in an improved hemodynamic status and decreased likelihood of intrauterine fetal demise of the donor twin” [22]. The results seem to support this hypothesis as SQLPCV led to a reduction in the risk of intrauterine demise of both twins compared with selective ablation (40 vs. 50 %) and higher rates of perinatal survival [23]. Finally, the Solomon technique is another method of laser ablation. After an initial SLPCV the entire placental vascular equator on the surface of the placenta is coagulated in a line. In a randomized trial comparing this technique to standard laser coagulation in patients with TTTS II, III or IV the equatorial technique resulted in lower rates of twin anemia polycythemia sequence (TAPS) and recurrence of TTTS (3 vs. 16 % and 1 vs. 7 %, respectively), but no significant difference in perinatal mortality or severe neonatal morbidity [24]. At present a prospective multicenter randomized trial was started to compare selective laser ablation and the Solomon technique (Solomon Study). At our center we currently perform a sequential selective technique. Laser ablation is associated with complications including chorioamnionitis, PPROM, preterm delivery, amniotic fluid leakage, vaginal bleeding, and placental abruption. In the Eurofetus trial, the overall risk for most complications was about 3 % [19]. A complication specific to pregnancies after laser ablation is the persistance of TTTS or development of post-laser TAPS in up to 13 % [25] which is caused by residual AV/VA anastomoses. TAPS is a milder variant of, often reversed, TTTS. The anastomoses lead to a shifting of red blood cells with the recipient becoming anemic and the donor polycythemic. In approximately 25 % of cases, post-laser TAPS can also result in an anemic donor and a polycythemic recipient [26]. For this reason, pregnancies after laser ablation require intensive follow-up with ultrasound and Doppler assessment on a weekly basis to detect TAPS or intrauterine growth restriction (IUGR). TAPS is detectable by Doppler measurements of the middle cerebral artery (MCA). If there is a discordance of peak systolic velocities (> 1.5 MoM) in the donor and < 1.5 MoM in the recipient twin) TAPS is likely. The therapy for TAPS depends on the gestational age at occurrence. Treatment options include (repeat) laser ablation, intrauterine blood transfusion to the donor, and delivery [27, 39]. If there is no indication for early delivery, babies should be delivered at 37 weeks of gestation because the risk for fetal demise increases overproportionally.
Twin Reversed Arterial Perfusion (TRAP) Sequence
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With an incidence of about 1 % of monochorionic twin pregnancies and 1 in 35 000 deliveries [28] twin reversed arterial perfusion sequence (TRAP) is a rare, unique complication of monochorionic twin pregnancy in which a twin with an absent or a non-functioning heart (“acardiac twin”) is perfused by its co-twin (“pump twin”) via placental arterial anastomoses. As the acardiac twin has no own placental circulation his blood supply is dependent from the pump twin´s circulation. His deoxygenated blood is shunted to the acardiac twin via AA anasto-
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26 Review
Conclusion
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For monochorionic twin gestations complicated by TTTS or TRAP sequence minimally invasive procedures can be offered to improve survival and outcome of affected fetuses. These procedures cause little trauma to the expectant mothers but PPROM following endoscopic treatment is still challenging. Patients
should be counselled interdisciplinary by prenatal medicine specialists and neonatologists to support individual decision making. Still unclear is the optimal treatment regime for stage I TTTS. Further randomized trials are needed here.
Interessenkonflikt: Die Autoren geben an, dass kein Interessenkonflikt besteht. References 1 Berghella V, Kaufmann M. Natural history of twin-twin transfusion syndrome. J Reprod Med 2001; 46: 480–483 2 Lewi L, Jani J, Blickstein I et al. The outcome of monochorionic diamniotic twin gestations in the era of invasive fetal therapy: a prospective cohort study. Am J Obstet Gynecol 2008; 199: 514–518 3 De Paepe ME, Shapiro S, Greco D et al. Placental markers of twinto-twin transfusion syndrome in diamniotic-monochorionic twins: a morphometric analysis of deep artery-to-vein anastomoses. Placenta 2010; 31: 269–276 4 Denbow ML, Cox P, Taylor M et al. Placental angioarchitecture in monochorionic twin pregnancies: relationship to fetal growth, fetofetal transfusion syndrome and pregnancy outcome. Am J Obstet Gynecol 2000; 182: 417–426 5 Mahieu-Caputo D, Dommergues M, Delezoide AL et al. Twin-to-twin transfusion syndrome. Role of the fetal renin-angiotensin system. Am J Pathol 2000; 156: 629 6 Bajoria R, Ward S, Chatterjee R. Natriuretic peptides in the pathogenesis of cardiac dysfunction in the recipient fetus of twin-twin transfusion syndrome. Am J Obstet Gynecol 2002; 186: 121 7 Karatza AA, Wolfenden JL, Taylor MJ et al. Influence of twin-twin transfusion syndrome on fetal cardiovascular structure and function: prospective case-control study of 136 monochorionic twin pregnancies. Heart 2002; 88: 271 8 Simpson LL, Marx GR, Elkadry EA et al. Cardiac dysfunction in twintwin transfusion syndrome: a prospective, longitudinal study. Obstet Gynecol 1998; 92: 557 9 Barrea C, Alkazaleh F, Ryan G et al. Prenatal cardiovascular manifestations in the twin-to-twin transfusion syndrome recipients and the impact of therapeutic amnioreduction. Am J Obstet Gynecol 2005; 192: 892 10 Quintero RA, Morales WJ, Allen MH et al. Staging of twin-twin transfusion syndrome. J Perinatol 1999; 19: 550 11 Lewi L, Jani J, Boes AS et al. The natural history of monochorionic twins and the role of prenatal ultrasound scan. Ultrasound Obstet Gynecol 2007; 30: 401 12 Lewi L, Lewi P, Diemert A et al. The role of ultra-sound examination in the first trimester and at 16 weeks’ gestation to predict fetal complications in monochorionic diamniotic twin pregnancies. Am J Obstet Gynecol 2008; 199: e1–e7 13 Dickinson JE, Evans S. The progression of disease stage in twin–twin transfusion syndrome. J Matern Fetal Neonatal Med 2004; 16: 95–101 14 Wagner MM, Lopriore E, Klumper FJ et al. Short- and long-term outcome in stage 1 twin-to-twin transfusion syndrome treated with laser surgery compared with conservative management. Am J Obstet Gynecol 2009; 201: 286 e1 15 Middeldorp JM, Sueters M, Lopriore E et al. Fetoscopic laser surgery in 100 pregnancies with severe twin-to-twin transfusion syndrome in the Netherlands. Fetal Diagn Ther 2007; 22: 190–194 16 Roberts D, Gates S, Kilby M et al. Interventions for twin-twin transfusion syndrome: a Cochrane review. Ultrasound Obstet Gynecol 2008; 31: 701–711 17 Rossi C, D’Addario V. Survival outcomes of twin-twin transfusion syndrome in stage I: a systematic review of the literature. Am J Perinatol 2013 Jan; 30: 5–10 18 De Lia JE, Cruikshank DP, Keye WR Jr. Fetoscopic neodymium:YAG laser occlusion of placental vessels in severe twin-twin transfusion syndrome. Obstet Gynecol 1990; 75: 1046 19 Senat MV, Deprest J, Boulvain M et al. Endoscopic laser surgery versus serial amnioreduction for severe twin-to-twin transfusion syndrome. N Engl J Med 2004; 351: 136 20 Rossi AC, D’Addario V. Laser therapy and serial amnioreduction as treatment for twin-twin transfusion syndrome: a metaanalysis and review of literature. Am J Obstet Gynecol 2008; 198: 147 21 Quintero RA, Comas C, Bornick PW et al. Selective versus non-selective laser photocoagulation of placental vessels in twin-to-twin transfusion syndrome. Ultrasound Obstet Gynecol 2000; 16: 230
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mosis to the lower half of the recipient twin via its iliac arteries. Perfusion of the upper torso and head is poor. Blood supply is barely sufficient to maintain metabolic activity and leads to hypoxic damage to developing tissues. The selective perfusion of the lower body causes various structural abnormalities in the acardiac twin [29]. Umbilical-venous return of further deoxygenated blood to the pump twin is conditioned by VV anastomoses, so the blood administration to the pump twin includes oxygenated blood from the placenta and deoxygenated blood from the acardiac twin. This may lead to chronic hypoxia and growth restriction in the pump twin and has also effects on the pump twins cardiovascular system [30]. Volume preload as well as pump afterload increase. Therefore, the pump twin may develop high-output cardiac failure including polyhydramnios, cardiomegaly, tricuspid regurgitation, pleural effusions, ascites, and hydrops fetalis. The development of cardiac failure depends on the size of the acardiac twin. Given a ratio of the acardiac twin to that of the pump twin of more than 0.70 the risk of heart failure increases from 10–30 % [31]. These criteria are associated with poor outcome. If TRAP is suspected diagnosis is confirmed by Doppler ultrasound revealing arterial blood flow towards the acardiac twin in its umbilical arteries. Mortality rates of 55 % for untreated TRAP have been reported [32]. In cases with one or more poor prognostic criteria, intrauterine intervention or delivery, depending on the gestational age, should be considered. Treatment options are laser ablation, bipolar cord coagulation, radiofrequency ablation (RFA), and fetoscopic cord ligation [33–35]. Laser ablation is performed with the patient under local anesthesia and access to the acardiac sac is achieved analogously to laser ablation for TTTS. The umbilical cord is visualized and coagulated near the placental insertion site. If the umbilical cord is too thick for complete coagulation the goal of cord occlusion is achievable by using a bipolar cautery forceps. Laser ablation in TRAP can also be performed as intrafetal laser ablation [36]. At our center we prefer RFA over laser ablation in pregnancies of more than 16 weeks of gestation. A radio frequency (at our center 17-gauge with a 2 cm umbrella) needle is inserted into the amniotic cavity of the acardiac twin under ultrasound guidance in local anesthesia. The abdominal wall at the base of the umbilical cord is targeted and the tines are deployed within the abdomen. The emitted energy is initially 10 watts and increased stepwise until the specific impedance is reached. Success of the operation is documented by the absence of flow from the pump twin to the acardiac twin in Doppler ultrasound. The outcome data of both techniques is comparable with survival rates of 80–90 % [37, 38]. Both techniques are safe for the mothers. Possible complications are uncommon and the same as in other invasive procedures such as chorioamnionitis, PPROM, preterm delivery, amniotic fluid leakage, vaginal bleeding, and placental abruption. A recent meta-analysis reported significantly lower rates of adverse pregnancy outcome when the treatment was performed before 16 weeks of gestation [37].
22 Quintero RA, Ishii K, Chmait RH et al. Sequential selective laser photocoagulation of communicating vessels in twin-twin transfusion syndrome. J Matern Fetal Neonatal Med 2007; 20: 763–768 23 Chmait RH, Kontopoulos EV, Korst LM et al. Stage-based outcomes of 682 consecutive cases of twin-twin transfusion syndrome treated with laser surgery: the USFetus experience. Am J Obstet Gynecol 2011; 204: 393 e1 24 Slaghekke F, Lopriore E, Lewi L et al. Fetoscopic laser coagulation of the vascular equator versus selective coagulation for twin-totwin transfusion syndrome: an open-label randomised controlled trial. Lancet 2014; pii: S0140-6736(13)62419-8 doi:10.1016/S01406736(13)62419-8 [Epub ahead of print] 25 Lopriore E, Slaghekke F, Middeldorp JM et al. Residual anastomoses in twin-to-twin transfusion syndrome treated with selective fetoscopic laser surgery: localization, size, and consequences. Am J Obstet Gynecol 2009; 201: 66 e1 26 Slaghekke F, Kist WJ, Oepkes D et al. Twin anemia-polycythemia sequence: diagnostic criteria, classification, perinatal management and outcome. Fetal Diagn Ther 2010; 27: 181 27 Lopriore E, Hecher K, Vandenbussche FP et al. Fetoscopic laser treatment of twin-to-twin transfusion syndrome followed by severe twin anemia-polycythemia sequence with spontaneous resolution. Am J Obstet Gynecol 2008; 199: 493 e1–493 e7 28 Moore TR, Gale S, Benirschke K. Perinatal outcome of forty-nine pregnancies complicated by acardiac twinning. Am J Obstet Gynecol 1990; 163: 907–912 29 Van Allen MI, Smith DW, Shepard TH. Twin reversed arterial perfusion (TRAP) sequence: a study of 14 twin pregnancies with acardius. Semin Perinatol 1983; 7: 285 30 Van Gemert MJC, Umur A, van den Wijngaard JPHM et al. Increasing cardiac output and decreasing oxygenation sequence in pump twins of acardiac twin pregnancies. Phys Med Biol 2005; 50: N33–42
31 Moore TR, Gale S, Benirschke K. Perinatal outcome of forty-nine pregnancies complicated by acardiac twinning. Am J Obstet Gynecol 1990; 163: 907 32 Lewi L, Valencia C, Gonzalez E et al. The outcome of twin reversed arterial perfusion sequence diagnosed in the first trimester. Am J Obstet Gynecol 2010; 203 (213): e1–e4 33 Ville Y, Hyett JA, Vandenbussche FP et al. Endoscopic laser coagulation of umbilical cord vessels in twin reversed arterial perfusion sequence. Ultrasound Obstet Gynecol 1994; 4: 396 34 Lee H, Wagner AJ, Sy E et al. Efficacy of radiofrequency ablation for twin-reversed arterial perfusion sequence. Am J Obstet Gynecol 2007; 197: 459 35 Deprest JA, Audibert F, Van Schoubroeck D et al. Bipolar coagulation of the umbilical cord in complicated monochorionic twin pregnancy. Am J Obstet Gynecol 2006; 28: 688 36 Jolly M, Taylor M, Rose G et al. Interstitial laser: a new surgical technique for twin reversed arterial perfusion sequence in early pregnancy. BJOG 2001; 108: 1098–1102 37 Pagani G, D’Antonio F, Khalil A et al. Intrafetal laser treatment for twin reversed arterial perfusion sequence: cohort study and meta-analysis. Ultrasound Obstet Gynecol 2013; 42: 6 38 Cabassa P, Fichera A, Prefumo F et al. The use of radiofrequency in the treatment of twin reversed arterial perfusion sequence: a case series and review of the literature. Eur J Obstet Gynecol Reprod Biol 2013; 166: 127 39 Diehl W, Glosemeyer P, Tavares De Sousa M et al. Twin anemia-polycythemia sequence in a case of monoamniotic twins. Ultrasound Obstet Gynecol 2013; 42: 108–111 40 Gardiner HM, Matsui H, Roughton M et al. Cardiac function in 10-yearold twins following differetn fetal therapies for twin-twin transfusion syndrome. Ultrasound Obestet Gynecol 2014; 43: 652–657
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