Glycine as a potential window for minimal access fetal surgery.

Abstract

Carbon dioxide insufflation of the uterine cavity in sheep enables electrocautery to the surface and superficial tissues of the fetal lamb, using minimally invasive surgery. Absorption of the CO2, however, causes a potentially lethal acidosis. To enable the use of electrocautery dissection of the fetal sheep, without using gas, we have partially replaced the amniotic fluid with 0.5% glycine. To determine whether glycine would have any short- or long-term deleterious effects on the developing fetus, we replaced amniotic fluid with 0.5% glycine in 10 normal fetuses at 101 days of gestation (normal gestation 145-149 days), without later replacing it with the removed amniotic fluid. Histological changes were then sought in the skin, gastrointestinal tract, and pulmonary tree, at 2 ('early', n = 5) or 6 weeks ('late', n = 5) after the introduction of the glycine. There were no histological differences between these and normal sheep at either time point. The use of glycine as a replacement for amniotic fluid subsequently enabled us to carry out electrocautery dissection of the sheep fetus and electrocoagulation of any bleeding vessel. Its use was not associated with any apparent untoward effects. Therefore, it has the potential to be used in minimally invasive surgery on the fetal trachea or on an enlarged fetal bladder.