Which organs can be affected by adhesions?

Mostly intestines. Usually the intestines are most affected by adhesions, but in theory, other organs could be as well. When intestines are affected, adhesions can cause a blockage that may require stomach decompression with a tube through the nose and sometimes surgery.
Many possibilities. Adhesions or scar tissue can be found anywhere. Adhesions are part of the healing process. They can scar together loops of bowel in the abdominal/peritoneal cavity causing bowel obstruction. Most of the time, bowel adhesions can be treated without surgery, using bowel rest, bowel decompression and fluids. Scar/adhesions in joints shoulders and back, occasionally need surgery.