Thanks for your question on Healthcare Magic. I can understand your concern. Fluid in the lungs is known as pleural effusion. Your husband is having pleural effusion after abdominal surgery (colon resection). This can be due to either of the following causes. 1. Infective etiology 2. Fluid resorption in the pleural cavity after abdominal surgery. Tobacco confirm this, we need to examine and do certain tests of fluid. So consult pulmonologist and get pleural fluid aspiration and send sample for fluid routine and microscopic examination and culture examination. Don t worry, he will be alright. Hope I have solved your query. I will be happy to help you further. Wishing good health to your husband. Thanks.