Carbon dioxide fetoscopic technique to enhance visualization in cases of placental laser ablation for twin twin transfusion syndrome

Dear Editor, we present a case of twin twin transfusion syndrome (TTTS) with carbon dioxide (CO2) insufflation enhancing visualization to complete fetoscopic laser ablation (FLA). 19-year-old P0 presented at 24 weeks with symptomatic stage 1 TTTS, with regular uterine contractions. Imaging revealed anterior placenta, maximum amniotic fluid (AF) vertical pockets of 12 and 1 cm in the recipient and donor sacs. Doppler studies of the umbilical artery, ductus venosus and middle cerebral arteries were normal. Twin B, recipient, was noted to have an epignathus teratoma that was primarily external, measuring 6.4 × 5.6 × 5.6 cm, with a small intraoral portion, 3.5 × 4.3 × 2.4 cm. The tracheal position, esophageal diameter and stomach bubble appeared to be normal in size on fetal magnetic resonance imaging, suggestive of a lack of airway or esophageal obstruction. The patient was informed of the alternative options of selective reduction of the anomalous fetus vs termination of pregnancy, which she declined. We were concerned the AF would be cloudy and dark due to presence of the teratoma with a larger external component. Approval was obtained by the Fetal Therapy board and patient was informed of the experimental nature of the procedure. Uterine entry was by seldinger technique using a 12 Fr cannula, AF was dark brown, limiting visualization (Fig. 1A). 200 mL of AF was drained, then 200 mL of heated, humidified CO₂ was insufflated into the uterus, using a 60 mL syringe, minimizing concerns regarding increased intrauterine pressure. CO₂ gas rose to the anterior surface when in supine position, providing access to the anterior placenta. The inter twin membrane and anastomosing vessels were identified (Fig. 1B) and FLA was performed successfully. CO₂ was then evacuated using 60 mL syringe under ultrasound guidance. Following surgery, the Dopplers remained stable and the fluid normalized in both sacs by the end of the first week. Fetal MRI was performed at 28 weeks which revealed a significant increase in size, extra-oral measuring 8.7 × 8.6 × 10.2 cm, volume of 400 mL and intraoral measuring 3.5 × 4.8 × 4.1 cm with concerns for airway compromise. Twin B was noted to be growth restricted. Ex utero intrapartum treatment (EXIT) procedure was planned and performed successfully at 29 weeks due to repetitive spontaneous decelerations with minimal variability. Birth weight of twin A was 1460 g and her postnatal course was uneventful. Twin B weighed 700 g, the teratoma was debulked using a GIA^TM stapler (Medtronic, Minnesota, USA) and the airway was secured by tracheostomy. However, she remained critical and died on day of life 19. Placental pathology did not demonstrate any residual anastomoses.