7 days after a head injury of a2 year old baby with no symptoms or other than subcutaneous heamatoma at the sight of injury ( 3 x 3 cm). what to do?

Don't be alarmed: After a head injury a hematoma is fairly common. It can take several weeks for the blood to be reabsorbed into the body. When the blood is reabsorbed it typically leaves behind calcium that potentially can be felt for months after the injury but this will also go away over time. Bleeds inside the head almost always happen within the first day after an injury. Ice or heat can help with pain.

Observe: When there are no symptoms immediately after the trauma and there was no loss of consciousness, the likelihood of having complications so far out after the injury is very low. Fortunately for this child, the injury does not appear to have been severe.

child head injury: At 7 days out the danger of life threatening intracranial injury may have passed but subdural hematoma can still exist. Unfortunately "symptoms" in any child 2 yrs of age are are subtle and far less easy to elicit than those of a patient who can communicate. And some subcutaneous hematomas can become infected through almost undetectable breaks in skin. A through exam is in order.

Close observation: The scalp hematoma will typically resolve over the course of several weeks. If no other problems, just closely observe the child for another week. It sounds like the child is doing fine.