ABSTRACT

• Despite of advances in perinatal management and treatment modalities congenital diaphragmatic hernia(CDH) remains a frustrating problem. Although the sheep has proven to be a reliable experimental model for the production of intrauterine CDH, the rabbit may have some advantages. These include lower cost, smaller body size, year-round availability, high number of fetuses per pregnancy, and short gestational period. To evaluate the feasibility of the rabbit model of CDH, twenty-seven pregnant New Zealand rabbits were utilized. Hysterotomy and an operative procedure for creating a diaphragmatic defect on gestational day 24 or 25, in two fetuses of each pregnant rabbit were performed. In one fetus of one cornu of the uterus, the left fetal diaphragm was excised through an open thoracotomy(DH group). In another fetus in the other cornu, CDH was created and the trachea clipped(Surgiclip, USSC, Norwalk, Conn., USA) (TL group). Delivery was by Cesarean section on 30 days of gestation. Among twenty- seven pregnant rabbits, 12 in the DH group and eight in the TL group were born alive. The most common herniated organ was the left lobe of the liver. In thee DH group, the lungs were hypoplastic with decreased lung weightlbody weight ratio, reduced numbers of alveoli, thicker media of the pulmonary arteries, and immature alveoli. In TL group, the alveoli were more mature and did not differ from the control animals. In conclusion, (1) pulmonary hypoplasia develops in the fetal rabbit diaphragmatic hernia model and (2) simultaneous tracheal ligation prevents pulmonary hypoplasia.
• Keywords: diaphragmatic hernia; fetal surgery; tracheal ligation; animal model