Health check up is supposed to pick up silent diseases which can produce symptoms and complications later on in life.
Common examples are - diabetes, hypertension, silent malignancy, etc.
In the last few years I have seen half a dozen patients presenting with upper or lower GI bleed who had undergone a health check up few weeks or few months back. The fact is that portal hypertension is a silent disease. On examination, the prominent veins in the epigastrium are rarely seen specially in lying down position and the enlarged spleen is rarely felt clinically till it increases 3 times the normal size. The most common cause of lower GI bleed is angio-dysplesia. Unfortunately, till today there is no method of finding out on a health check up that which person is harbouring angio-dysplesia in the colon which can anytime cause a sudden lower GI bleed.