A Rectal prolapse: This is a protrusion of rectal tissue through the anus to the exterior of the body that becomes visible outside the body. In hamsters although very rare it does happen occasionally and is often associated with long term diarrhea or long term constipation. There may be bleeding and or tissue that protrude from the rectum, a hamster with constipation will have stools that are often dry hard and may be abnormally large or small.
Intussusceptions: This occurs when a section of intestine twists or over rides another section trapping it inside in a telescoping effect but does not exit the anus. When this occurs it creates an obstruction in the bowel and this can lead to abdominal swelling, (distended or extended stomach) and passing stools (poop) mixed with blood and mucus.
Rats, mice and hamsters don't usually show symptoms of being in pain and are able to mask pain very well, this is an evolutionary adaption. Therefore an animal suffering in any pain may be evident in altered behavior. Most evident this may be seen as a hunched posture, a ruffled unkempt coat / fur, vocalization, greater or less activity, and the animal will resent being handled with a reluctance to move or be moved, an abnormal gait, aggressiveness, or a reduction in food and water consumption.