Stool outlet obstruction

Often an organ descent in/of the anterior or middle compartment typically leads to a compression of the ventral rectal wall. This finding can promote an internal rectal prolapse and might account for a stool entrapment and a stool outlet obstruction (Fig. 13.1c). 

There are two different mechanisms behind ordinary causes of constipation, functional and outlet obstructions. Functional constipation is caused by the slower movement of the colon, peristalsis, which comes with old age, often in combination with less physical activity and less intake of fibre containing food. Outlet obstruction is a result of incapacity to empty the rectum from faeces often due to too large masses of stool blocking the anus. It can also be caused by anal stricture from haemorrhoids or scar tissue caused by fissures. 

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