system
Given the following post, respond as if you're commenting on Reddit:
human
As a hospital security dispatcher, I see a lot of elderly patients who come into the ER for rectal bleeding. Why is this so common in the elderly population?

To clarify. I work in the dispatch office which is directly across from the ED triage. I have access to a program which displays all ER patients info and their issues. I have no direct contact with the patients or staff and it would be distasteful to ask the staff in person. Any ideas?
gpt
Elderly patients often have poor diets(no fiber), little fluid intake, and are usually immobile/static(no abd muscle flexion to help the intestines). They also have decreased smooth muscle tone in the intestines(just like any other muscle in the body), and are more prone to tears due to the age and fragility of the intestinal wall.

Even though we usually just say rectal bleeding, this is only half the case. 50% of the time, if they are actually bleeding, they are due to hemmorhoids which are caused by increased thoracic pressures due to pushing while pooping(Weight lifters get them too)--its called the vasalva maneuver and is the reason you're told to breath while you lift and poop. This increased pressure causes the internal and/or external rectal veins(or other veins) to abnormally expand and possibly rupture(you go to wipe), thus bleeding. If you have these, it will be bright red blood. This is probably what you are referring to and its mainly due to poor diet, immobility(obese get this as well), and as a result, excess straining while pooping. 

The other 50% of the time, the patient actually has a GI(stomach, small intestine, etc) bleed but can present with signs of rectal bleeding. Upper GI bleeds are usually detected by the presence of dark colored stool, while lower colon and rectal bleeds are often characterized by gross blood or stool mixed with bright red blood. (darker color is due to the intestines breaking down the hemoglobin, thus allowing oxidation of the iron). We call dark stools with blood, "occult blood", and we perform a DRE/stool guiuac test(stick a finger up your butt) to confirm--the patient then goes for a EGD scope or colonoscopy if positive. Upper GI bleeds  can be caused by poor diet but is often due to some underlying malignancy(cancer--chemo drugs wreak havok on the GI system due to the fast turnover), disease(diabetes, htn), ulceration(peptic or duodenal ulcer), or trauma.