Hidden pain in the lower abdomen while bending may be caused by lumbar spine slippage, lumbar disc herniation, and abdominal wall muscle injury. 1. Lumbar spondylolisthesis: there is unstable lumbar spondylolisthesis, if the lumbar spondylolisthesis occurs in the process of bending, it will spread to the abdomen with the pulling of muscle tissues, resulting in pain. 2. Lumbar disc herniation: If the nerves in lumbar 1 and 2 are compressed, they will radiate to the lower abdomen and cause abdominal pain. 3. Muscle damage to the abdominal wall: If there is strenuous exercise, such as sit-ups, or if the abdomen has been subjected to a direct violent attack, resulting in damage to the muscles of the abdominal wall. When bending over, it will involve the injured area, thus causing pain in the abdomen. Hidden pain in the small of the abdomen when bending over may also be seen in the presence of serious lesions in the abdominal cavity such as intestinal ulcers, bowel cancer and other diseases. If the symptoms of pain in the abdomen persist without relief, you need to seek medical treatment.