OP05.09: Preliminary experience in Poland with fetoscopic laser surgery for severe TTTS

Abstract

Objective: To compare the transfer of technetium-99m labelled red blood cells (99mTc RBCs) in monochorionic (MC) placentas, MC placentas after laser coagulation of the vascular anastomoses for TTTS and fused dichorionic (DC) placentas. Methods: Placental perfusion study with 99mTc O Rh – RBCs in 5 MC, 5 lasered MC and 5 fused DC placentas. The arteries of twin 1 were injected with 20–30.10 × 9 99mTc RBCs diluted in 100 mL NaCl, whereas the vessels of twin 2 were rinsed with 200 mL NaCl. The % of transferred 99mTc RBCs was calculated by dividing the radioactivity measured in the rinsing solution of twin 2 by the initial radioactivity injected in twin 1. Afterwards, each placenta was injected with dyed barium sulphate to document the angioarchitecture. Results: GA at birth was similar in the 3 groups. None of the lasered MC and fused DC placentas had visible anastomoses, whereas all 5 MC placentas had visible anastomoses-1 had only small arteriovenous (AV)-venoarterial anastomoses (VA) without an arterioarterial (AA) anastomosis, 4 had an AA with AV/VA. The % of transferred 99mTc RBCs in lasered MC placentas (0, range: 0–000012) was similar to fused DC placentas (0, range: 0–001760) (NS), but significantly lower than in MC placentas (8.5, range: 1–66) (p < 0.01). In MC placentas, the larger the AA, the higher the % of transferred 99mTc RBCs. Conclusion: In MC placentas successfully separated by laser coagulation of the vascular anastomoses, the transfer of 99mTc RBCs was not significant and similar to fused DC twin placentas. Therefore, laser seems to functionally separate the 2 fetal circulations.