Congenital diaphragmatic hernia: lung compliance after antenatal tracheal obstruction or surgical correction of the defect.

Fetal lambs with diaphragmatic herniae (CDH) created surgically at 73 days' gestation were subjected to three different forms of intrauterine correction: silastic patch correction of the diaphragmatic defect plus an abdominal patch at 101 days gestation; an intrathoracic "silo" at 101 days; and a tracheal "plug" obstruction at 101 or 129 days. At 143 days' gestation (term 145-149 days), the lambs were delivered by caesarean section and ventilated for 30 min before undergoing respiratory compliance measurements. These results were compared to those of normal lambs and animals with uncorrected herniae. The total respiratory system compliance values in those groups undergoing corrections were remarkably similar: those with any form of correction had a significant improvement (P < 0.05) compared to those with herniae and no correction (patch = 1.57 = ± 0.182 ml/cm H2O; silo = 1.53 ± 0.179; plug at 101 days = 1.66 ± 0.311; plug at 129 days = 2.00 ± 0,175; without correction = 0.62 ± 0.073). None, however, reached the values of those with normal lungs: 2.72 ± 0.223 (P < 0.05). This improvement in compliance in all corrected groups suggests that fetal tracheal obstruction is as effective as the two more invasive forms of open fetal surgery carried out in this study and, as this procedure lends itself to surgery through a small uterine incision or "minimally invasive" surgery, it may be the procedure of choice to reduce the incidence of preterm labour for those human fetuses undergoing antenatal correction of a CDH.bb.