Laser for twin-to-twin transfusion syndrome: a guide for endoscopic surgeons

Abstract

Twin-to-twin-transfusion syndrome (TTTS) is the most important cause of handicap and death in monochorionic twin pregnancies. It is caused by a certain pattern of anastomoses between the two fetal circulations leading to an unbalanced blood and fluid transfer. This leads to severe amniotic fluid discordance and variable degrees of cardiac dysfunction. Untreated, this condition has a very poor survival rate. Fetoscopic laser has been shown to be the best first line treatment, which aims to dichorionise the placenta therefore arresting the inter-twin transfusion. Fetoscopic laser is a causative therapy, which aims to functionally create a dichorionized placenta hence arresting inter-twin transfusion. This is achieved by percutaneous sono-endoscopic coagulation of placental anastomoses. In addition, redundant amniotic fluid is drained. Fetoscopic laser coagulation of chorionic plate anastomoses is safe and effective. There is level I evidence that it is the best treatment modality, in particular when the placental surface is lined along the vascular equator. A recent meta-analysis confirmed an increased fetal survival and decreased risk for neonatal and pediatric neurologic morbidity. Laser therapy is the first line therapy for TTTS. The technique is quite standardized and safe and effective in experienced hands. Herein we describe the technique and current instrumentation used for this procedure.

Keywords: Fetoscopy; Laser; TOPS; TTTS; monochorionic twin pregnancy; twin twin transfusion.

Conflict of interest statement

JD is partly funded by the Great Ormond Street Hospital Charity Fund. LVDV and JvdM is supported by the Erasmus+ Programme of the European Commission (2013-0040). LL is funded by the FWO (Fonds voor Wetenschappelijk Onderzoek) (1804718N). Our research on novel instrumentation in fetal surgery is supported by an Innovative Engineering for Health award by the Wellcome Trust (WT101957) and the Engineering and Physical Sciences Research Council (ESPRC) (NS/A000027/1).

Copyright © 2019 Facts, Views & Vision.

Figures

Figure 1

Image from a placenta of a monochorionic pregnancy. Multiple anastomoses are present: 1AA (open star) ; 2 VV (full star) ; multiple AV (dotted circle) ; multiple VA (full circle). Reproduced with permission and copyright: UZ Leuven, Belgium.

Figure 2

Left: Schematic view of the placenta with the different types of anastomoses. Right: A) normal cotyledon with paired vessels, from and to the same fetus. B) Shared cotyledon, with artery and vein belonging to a different fetus. C) Superficial unpaired vessels, that do not connect closely. Drawing Myrthe Boymans, Reproduced with permission and copyright: UZ Leuven, Belgium.

Figure 3

Trocar entry with Seldinger technique. A) A 18G needle is inserted in the uterus. B) The guidewire is advanced through the needle. C) The needle is removed and the cannnula is advanced over the guidewire. D) The guidewire is withdrawn to leave only the cannula as entry to the uterus. Reproduced with permission and copyright: UZ Leuven, Belgium.

Figure 4

Fetoscopic views of different landmarks used for mapping of the placenta. A) umbilical cord ; B) the membrane appears as a white line, donor vessels can be seen leaving under the membrane ; C) veins have a more typical red (oxygenated) color and arteries are darker (deoxygenated blood) ; D) The donor can be seen stuck under the membranes. E and F) schematic drawings how the stuck twin can relate to the vascular equator. Drawing Myrthe Boymans, all images reproduced with permission and copyright: UZ Leuven, Belgium.

Figure 5

Typical view with ultrasound (left) and fetoscopically (right) during active lasering. Reproduced with permission and copyright: UZ Leuven, Belgium.

Figure 6

Solomon-technique: after coagulating the anastomoses, coagulation points are connected by a continuous line from one placental border to the other for complete coagulation of all small vessels that may have been missed initially. This should lead to functional “dichorionization”. Drawing Myrthe Boymans, all images reproduced with permission and copyright: UZ Leuven, Belgium.

Figure 7

For an anterior placenta a ‘curved scope can be used to achieve a more perpendicular view. Drawing Myrthe Boymans, reproduced with permission and copyright: UZ Leuven, Belgium. Photo: reproduced with permission from Karl Storz, Tuttlingen, Germany.