Bruises can be very disconcerting because they can often appear when you don't recall the injury
that caused them, and, even when you do remember a minor trauma the bruise
itself can look like a serious injury. Overall, it sounds like your bruise is probably a mild injury to the deep tissue of the thigh, hence the yellowish color. A bruise is what results when there is bleeding into body tissues following a mechanical trauma such as a bump or a fall. Bruises close to the surface in people with light-toned skin will often look black or blue initially because of the blood accumulating under the skin. However, over time the pigment in blood begins to break down and turn from black/blue to yellow/green shades. In addition, bruises that result from bleeding into deeper tissue can often appear more on the yellow spectrum up front.
If you have any concerns about this injury, it is always a good idea to make an appointment with your primary care physician
. He or she can examine the injury and make sure that it is healing properly. In addition, if you find yourself bruising very easily or in situations when you don't remember the initial injury, that is also something you should discuss with your physician. Hopefully this bruise will heal without event and you will have no further run-ins with the table!