Final answer:
The most frequent form of internal bleeding in children with hemophilia is joint bleeding, due to the inadequate production of clotting factors that prevent the blood from clotting properly, resulting in spontaneous and potentially damaging bleeding episodes into the joints.
Step-by-step explanation:
The most frequent form of internal bleeding in a child with hemophilia is joint bleeding. Hemophilia is a genetic disorder that impairs the body's ability to make blood clots, a process necessary to stop bleeding. Due to a deficiency in clotting factors, such as factor VIII in hemophilia A or factor IX in hemophilia B, individuals with this condition experience spontaneous bleeding episodes, particularly into joints, which is known as hemarthrosis.
These bleeding events can cause significant joint damage and disability if not properly managed with clotting factor replacement therapy.