Objective To compare the effect of ultrasound guided intra-amniotic cavity and fetal lung injection ofpulmonary surfactant（PS）to prevent lung injury in premature rabbits.MethodsFifteen pregnant New Zealand rabbits wererandomly divided into fetal lung injection PS group（lung group）

amniotic cavity injection PS group（amniotic cavity group）andcontrol group

each group has 5 rabbits.On the 27 th day of pregnancy

rabbit fetuses were removed through cesarean section 1 hafter injection.The survival time of premature rabbits in each group was observed

the content of dipalmitoyl phosphatidylcholine（DPPC） and interleukin-6（IL-6） in bronchoalveolar lavage fluid were detected. Lung tissue was taken for lung injurypathological score

the expression level of PS-active substance associated protein-A（SP-A）and apoptosis index were detected.Morphological changes of type Ⅱ alveolar epithelial cells were observed by electron microscopy.ResultsCompared with thecontrol group

the survival time of premature rabbits in lung group and amniotic cavity group was significantly prolonged

thecontent of DPPC and SP-A expression level were increased

the apoptosis index of lung tissue and the pathological score of lunginjury and IL-6 content were decreased.All were statistically significant（all P<0.05）.The lamellar bodies of type Ⅱ alveolarepithelial cells was increased

and the swelling of endoplasmic reticulum was decreased. Compared with the amniotic cavitygroup

the content of DPPC

SP-A expression level and IL-6 content in preterm rabbits of lung group were increased

and thedifferences were statistically significant（all P<0.05）

and there were no significant difference between the remaining indicators.ConclusionBoth intra-amniotic and fetal lung injection PS can prevent lung injury in premature rabbits effectively.Comparedwith PS injected into amniotic cavity

PS injection into fetal lung with the same amount can obtain greater benefits

which isexpected to be a new treatment to prevent lung injury in premature infants.