Our colon is a designed to move like an earthworm.
It has two muscular layers - one running the length of the tube, the other encircling it.
One contracts and the tube stretches out, lengthening.
One contracts and the tube constricts, shortening.
We're not aware of our colons moving; the muscles are involuntary. They undergo large waves of contraction, called peristaltic waves, moving our stool forward.
There's very little pathology associated with the muscular wall of our colon:
A rare congenital disease called Hirshsprung's disease is one sad example - a portion of the colon is missing the nerve cells needed to stimulate contraction and so infants can suffer life-threatening complications.
Rarely a part of a colon is removed for slow-transit constipation. Once I had to examine ('gross in') a large portion of the colon removed for constipation. It had very thin walls and the. entire. colon. was. full. of. thick. sticky. brown. poop. ( I still remember it). Everything I documented about that colon was only the after effects of some unknown cause - why had that happened, why was the colon no longer pushing stool through? We can look for the evidence of laxative abuse, but that was not found in this case. Nothing in our pathology report would tell you why there was slow-transit constipation.
I just said that there is little pathology associated with the muscular wall of our colons, but we all know that is not true. Colon motility problems are a big health problem - diarrhea, constipation, irritable bowel syndrome - but there is no pathology-based description. Pathologists are not curious about what people consume. In fact, gastroenterologists, gastrointestinal pathologists, and colorectal surgeons (together, the triumvirate of gut doctors), are all remarkably not curious about diet. They just really don't seem to care about what people consume. I have met psychiatrists more interested in diet than gastroenterologists*.
If there is a vacuum of physicians not being curious about diet, it is being filled, like a constipated colon, with lots of bad advice from medical quacks. Extreme diets, specialized supplements, colonic washes and clay enemas are all being pushed and sold by those with no expertise. People suffer and lose hope without a competent, scientifically-based approach to their colonic health. Physicians should step up to the plate, no pun intended, and get curious about what patients eat and how it affects their health and disease.
What I like about pathology is that we have the answers. As someone joked to me, we are keeping the answers to most questions under the microscope. But sometimes there's no pattern or abnormality to be found. It's hard for me to admit, but sometimes there is no physical finding to document. But just because it doesn't exist under the microscope, doesn't mean it is not a real, physical process.