Cola-Colored Fluid from Lungs - 1254988

Not sure I'm in the right place, but I have a ? For Dr. West. My father-in-law had fluid taken off his lungs in the doctors office by his lung doctor. This last time the fluid that came out was the color of cola, doc had a concerned look on his face, in the past the fluid was beer colored. It was tested for cancer and bacteria, nothing found. However, the doctor has sent him to have a cat scan, which did reveal a spot on his lung. He said the spot could be 15 different things. He has scheduled my father-in-law for a pet scan, a plural effusion at the hospital, and a scan on his lymph nodes. The last tests mentioned have not been performed yet. What do you think of all this, and why do you think the fluid was so dark? We feel the doctor knows more than he is telling us. Thank you.

There are a lot of things that can discolor pleural fluid, including infection and blood. Blood, in turn, can come from many sources, including cancer. The most important tests to evaluate why pleural fluid has changed color are the lab tests on the fluid itself. These lab tests can differentiate two broad categories of fluids, transudates and exudates. Each of these groups themselves then have many causes, amongst which lung cancer is only one. Additional tests on the fluid are then guided by these initial results. Cytology (looking at cells under microscope) can help with looking for cancer, cultures can help with looking for infection, and so on.