It depends on the amount of the internal bleeding. An average of 24 hrs.

Faith is correct but fair skinned people tend to bruise quickly within an hour or less. I am speaking from experience.

It depends on several factors, including: 1. What part of the body got the injury. 2. How hard the impact was to that part of the body. 3. The person's state of health --do they take any blood thinners even aspirin on a regular basis? 4. Is the person generally in good health? Does the person have sound nutrition, which if not, can cause easy or much more severe bruising (bleeding under the skin) if certain vitamin and minerals are deficient. 5. Did the person who got the injury put anything like ice or other first air on the area soon after the injury? 6. The person's age. Older people generally have more thin skin, more fragile capillaries and veins, and weaker muscle tone. Therefore, they will tend to bruise more severely and easily, and the bruise will appear more quickly and take a longer time to fade away. It is a very individual situation. One person might trip and fall into a table and hit their leg muscle hard. Let's assume they put nothing like ice on the spot, and just yelled and cursed for 20 minutes until the severe pain subsided. They could show a bruise within an hour, or if they have good strong muscles and veins, it might not start to discolor and show (although it could be very sore) for 1-3 days, even longer. The deeper the injury, often the longer it takes for the discoloration to show and the hematoma (the blue-purple coloring we see with bruises at first) to come up to the top layers so we can see it under the skin. Some people who have great health and get plenty of vitamin C and B complex vitamins and who are in good muscular shape, don't show a bruise at all, unless they take a very hard blow in an area where the skin and muscles and vascular system is much more fragile and "thin" (the facial area for example, like around the eye). How fast a bruise shows up is very individual, and likewise, how long it takes to fade to the yellow-green colors then disappear is also very individual, based on the factors mentioned above.

Is it possible for a child to have suffered a hit and not show bruising for several days?