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

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Abstract

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

Introduction

The prerequisite for the development of twin-to-twin transfusion syndrome (TTTS) is the existence of placental vascular anastomoses which are present only in monozygotic multiple pregnancies with monochorionic placentas [1], [2]. In 10–20% of these pregnancies, severe TTTS may occur owing to an imbalance in net blood flow from one twin to the other. Thereby, one fetus (recipient) becomes hypervolemic and polyuric, leading to progressive polyhydramnios and congestive heart failure, whereas the other fetus (donor) becomes hypovolemic and anuric, leading to anhydramnios (stuck twin) and growth restriction.

Severe second trimester TTTS carries a high risk for fetal death (80–100%) if left untreated. Rupture of the membranes owing to the extreme polyhydramnios, miscarriage and extremely preterm delivery, as well as intrauterine death are the main complications contributing to the high perinatal mortality of the syndrome. As fetal viability is not yet achieved during the second trimester of pregnancy, delivery is not a realistic option for the management of these pregnancies.

So far, two therapeutic approaches have been developed for the treatment of TTTS: serial amniodrainages and endoscopic laser coagulation of placental vascular anastomoses. The first one improves the symptoms by reduction of intra-amniotic pressure, thus decreasing the risk for miscarriage and preterm delivery and, thereby, prolonging the pregnancy. The rationale for endoscopic laser coagulation is the interruption of blood flow in the underlying morphological substrate, offering a causal treatment option [3], [4]. In a previous study, we have compared endoscopic laser surgery (73 pregnancies) versus serial amniodrainages (43 pregnancies) and we have found that the laser technique offered a more effective alternative of treatment in severe mid trimester TTTS [4]. The proportion of pregnancies with at least one survivor was significantly higher in the laser group (79%) than in the amniodrainage group (60%). Furthermore, laser coagulation as a single invasive procedure led to a significantly higher median gestational age at delivery (33.7 weeks versus 30.7 weeks) and a higher median birthweight (1750 g versus 1145 g for donors, 2000 g versus 1560 g for recipients). In a second study including 121 patients, we have correlated clinical and sonographic parameters, in particular Doppler results, with pregnancy outcome after laser coagulation, to estimate their prognostic value [5]. This study also showed a tendency towards further improvement of fetal survival with this technique.

The aim of the present study was to compare obstetrical outcome of the first group of patients [4], who underwent endoscopic laser coagulation in our centre, with the following group of 127 patients.

Section snippets

Materials and methods

This was a prospective study on 200 patients with severe mid trimester TTTS referred to our centre for endoscopic laser coagulation of placental anastomoses between January 1995 and September 1999. For comparison of data, the whole group of 200 pregnancies was divided into two groups: group 1 consisted of the first 73 cases, whose outcome has been reported already [4], group 2 consists of 127 consecutive pregnancies treated between June 1997 and September 1999. In all cases, parents gave

Results

The overall survival rate (up to at least 6 months of age) increased from 61% (89/146) in group 1 to 68% (172/254) in group 2. The percentage of pregnancies with survival of both fetuses was 42% (31/73) in group 1 and increased to 54% (69/127) in group 2 (P=0.142). Survival of only one fetus occurred in 37% (27/73) in group 1 and in 27% (34/127) in group 2, thus resulting in a survival rate for at least one fetus of 79% (58/73) in group 1 and 81% (103/127) in group 2. In detail, the survival

Comments

This study of a large population of pregnancies with severe second trimester TTTS confirms the improvements of outcome after laser therapy as compared to serial amniodrainages reported in a previous study [4]. Furthermore, it shows an increase in survival rates with growing experience in the technique, most likely attributable to a more selective identification and efficient coagulation of the placental vascular anastomoses.

Recently, survival rates of 71% for at least one twin at 4 weeks of age

Acknowledgements

This study was supported by the Biomed 2 Programme of the European Commission (‘Eurofoetus’, project number ‘PL962383’). L.Z. was a recipient of a research fellowship of that project.

References (10)

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