Carbon Dioxide and Horizontal Fluoroscopy in Intrauterine Fetal Transfusions

INTRAUTERINE transfusions of packed red blood cells to the erythroblastotic fetus must be performed under radiological guidance. The smaller, more premature fetuses are not candidates for early delivery and require blood replacement until viability is reached. A simplified method of introducing a catheter for intrauterine transfusion is the subject of this report. History Red blood cells have been shown to be absorbed intact from the fetal peritoneal cavity (1). Since the major cause of death of the erythroblastotic fetus prior to viability is anemia, therapeutic efforts are directed to red blood cell replacement by intrauterine transfusion to carry the fetus to viability. Selection of patients for intrauterine transfusion is based upon amniotic fluid analysis for bilirubin and the obstetrical history. Where the amniotic fluid bilirubin level indicates likely fetal death prior to thirty-two weeks gestation, the risk associated with intrauterine fetal transfusion is justified (2–4, 6, 8). The technic as outlined by Liley has been widely used and is as follows: Approximately five hours prior to transfusion, 20 cc of 76 per cent Urografin or similar radiopaque material is injected into the amniotic cavity. Time is allowed for the fetus to swallow the contrast material so that the fetal bowel becomes opacified and serves as a target for the needle puncture. Preliminary anteroposterior and lateral films of the maternal abdomen are taken with markers on the skin for a guide to the angle of puncture. An 18 cm 17-gauge Tuohy needle is inserted into the amniotic cavity and the stylet removed. A syringe of sterile saline is attached to the needle and slowly injected as the needle is advanced into the fetus. A resistance to the injection occurs as the fetal abdominal wall is penetrated, to be followed by a free flow after the needle tip enters the fetal peritoneal cavity. A 30 cm catheter is inserted through the needle and left in place for transfusion. Three cubic centimeters of methylglucamine diatrizoate is injected to confirm the position of the catheter. Characteristic curvilinear shadows of bowel loops will be outlined if the catheter is correctly positioned. No mention of fluoroscopy was made, but other authors have emphasized the use of image intensifiers for fluoroscopy in the anteroposterior projection (7). Technic Two modalities have simplified the procedure in our hands. One is fluoroscopy with a horizontal x-ray beam employing image intensifiers, the other is the use of carbon dioxide as a contrast agent. Anteroposterior and translaterai views of the maternal abdomen are taken with the patient supine. The roentgenograms are viewed for fetal position, with relation to the maternal spine and iliac crest. We have not found it necessary to inject contrast agents into the amniotic cavity for intestinal localization.