The sudden appearance of swelling in the abdomen of the thumb is commonly caused by the following: 1. due to crushing injuries, in some cases the thumb is crushed when closing the door with the hand, although it is not very serious, swelling will occur, such as lifting heavy objects without good cooperation, which can also cause crushing injuries to the thumb, resulting in swelling symptoms; 2. can be seen in chronic strain injuries, such as patients The swelling of the thumb may occur after long hours of pressing and pinching the thumb or holding objects. 3. There are also traumatic injuries to the thumb, such as puncture wounds, where bacteria can enter the wound and directly invade the tissue, causing secondary infections.