Diverticula, haemorrhoids and fissures: what can go wrong at the end of the gut

Healthy state

The wall of the colon has weak spots where blood vessels pass through the muscle layer. There, the lining can bulge outwards, probably encouraged by high pressure with hard stools. These little pouches are called diverticula Diverticula Small pouches of the gut lining that bulge through weak spots in the colon wall. When they become inflamed, it is called diverticulitis. , and having them is diverticulosis. They are common, especially with age, and usually cause no symptoms: of more than 2,000 people whose colonoscopy showed diverticula, only about 4 per cent developed inflammation over eleven years.

Everyone has haemorrhoids. They are vascular cushions at the end of the rectum that act like a seal to help close the anus. Haemorrhoidal disease is only present when they swell, bleed, itch or protrude.

The skin of the anal canal is very sensitive. An inner sphincter keeps the anus closed involuntarily, an outer one can be controlled at will. During a bowel movement both relax, and soft, formed stool slides out without straining (see the pelvic floor chapter).

What all three problems have in common is that hard stools, heavy straining and long sitting raise the pressure. Fibre that makes stools soft and bulky is therefore the foundation for all three.

Disrupted state: causes and effects

When a diverticulum becomes inflamed, diverticulitis develops: usually pain in the lower left abdomen, often with fever, sometimes with nausea or changed bowel habits. In the uncomplicated form, the inflammation stays within the gut wall; in the complicated form, abscesses, fistulas or a perforation develop. The diagnosis is usually confirmed by CT. In one study, people under 50 had a higher risk of recurrence.

For a long time everyone with diverticulitis received antibiotics. Two large randomised trials Randomised trial A study in which chance decides who gets the treatment and who does not, for comparison. This makes results particularly reliable. challenged this: in the Swedish AVOD trial (623 people) and the Dutch DIABOLO trial (528 people), a first uncomplicated diverticulitis healed just as well without antibiotics, with the same rates of complications and recurrence, even after two years. US gastroenterologists therefore now recommend antibiotics only selectively, but explicitly for people with weakened immunity. This is the doctor's decision, not yours: diverticulitis always needs to be seen by a doctor.

A persistent piece of advice is to avoid nuts, seeds, corn and popcorn with diverticula because they could get stuck in the pouches. A study of more than 47,000 men over 18 years found the opposite: those who ate nuts or popcorn at least twice a week tended to have diverticulitis less often, and there was no link with diverticular bleeding.

More fibre is associated with less diverticular disease. In a meta-analysis Meta-analysis An analysis that combines the results of several studies. It is only as good as the studies it includes. of five large cohort studies, the risk fell by about a quarter per 10 grams of fibre a day, most clearly for fibre from cereals and fruit.

Haemorrhoids cause problems when the cushions swell under pressure and the supporting tissue gives way: bright red blood on the paper, itching, seepage, a lump that comes out when straining. Long sitting on the toilet is considered a risk. In a US study of 125 people before colonoscopy, two thirds took their phone to the toilet; they sat longer, and phone use was linked to a 46 per cent higher risk of haemorrhoids. A Turkish study found no such link for phones, but did for sitting times over 20 minutes. What matters is probably the time, not the device.

An anal fissure is a small tear in the skin of the anal canal, usually after a hard stool. Typical is a sharp, burning pain during bowel movements that often lingers for a long time, and a little bright red blood. The pain makes the inner sphincter cramp, which reduces blood flow, the tear heals poorly, and fear of the next bowel movement makes people hold back stool. If a fissure lasts longer than about six weeks, it is considered chronic.

Important: blood from the anus is never automatically "just haemorrhoids". In people aged 50 and over who saw their GP with rectal bleeding, colorectal cancer was behind it in about 8 per cent of cases, according to a review. A colonoscopy is also often recommended after diverticulitis: in just under 2 per cent, colorectal cancer was hiding behind the picture, considerably more often in the complicated form.