Pulmonary effects of gastroschisis in a fetal rabbit model

Respiratory insufficiency is a significant cause of mortality and morbidity among infants with anterior abdominal wall defects (AWD). The aim of this study was to evaluate the pulmonary effects in a fetal rabbit model where gastroschisis was induced at midgestation. Gastroschisis (GAS) was created in 20 rabbit fetuses on day 22 or 23 of gestation (pseudoglandular phase; term = 31-32 days). The amniotic sacs of 13 fetuses were subjected to hysterotomy and amniotomy only (HYST), while 13 underwent a sham laparotomy which was immediately closed by sutures (SHAM). Eleven nonoperated littermates served as internal controls (CTR). Fetuses were harvested by cesarean section on day 31 of gestation prior to respiration. Pulmonary response was evaluated by left lung to body weight ratio (LWBWR), airway morphometry, and density of type II pneumocytes, as evaluated by the number of surfactant protein B-positive cells. Fetuses from the GAS group had significantly lower body weights than did CTR (P = 0.0129). Of these fetuses, 27% were growth-restricted, i.e., with a body weight under the 10th percentile of the CTR population. There were no differences in left lung weight and LWBWR among the GAS and CTR groups. Moreover, the GAS group had similar alveolar size, alveolar wall thickness, and type II cell density as CTR fetuses. Only mean terminal bronchiolar density (MTBD), which is inversely related to the alveolar space, was slightly increased in the GAS group, but without reaching significance (P = 0.0821). No effect on lung growth and maturation could be demonstrated in this study.