### instruction:
If you are a doctor, please answer the medical questions based on the patient's description.

### input:
Hi, my father is in hospital following an operation to remove half of his stomach and lower part of his esophagus following cancer of he gastroesopegeul junction.  A week after coming out he was rushed in to A&e with racing heart and difficulty breathing to be diagnosed with  collapsed lung and a pleural effusion.  2.5 weeks on they are still draining the effusion which is draining a cloudy yellow fluid and they are struggling to reinflate his lung. His heamaglobin levels were low yesterday and he has been given 2 bags of blood but he is still breathless.  The doctors do not seem to know what the problem is or they are not saying.  They have X-rayed Him numerous times and cannot see any problems except the fluid. they have also put a camera in to his lung to find only clear fluid which hey said was good fluid (assume they will have taken sample but no one has said this).  We are concerned the cancer has spread although no one is sayin anything, but we understand it could just be a post op side effect of abdominal surgery.  The surgeon could not see any signs of spreading during the op. Can you help me understand what is going on and why his lung will not reinflate and why fluid I still draining. Thanks for any further information you can provide.

### output:

Hi, in such a critical case we from online cant come to a conclusion, we can try to convey some causes, but they are not hard and fast facts, to ask your doctor, they are probables.  There could be slight oozing of blood, or infection, pus collection, there may be damage to the diaphragm or there could be metastasis, from an invisible part of malignancy. C.T.scan may relieve the fault to some extent. Thank you.