Diverticulitis

Diverticula are small bulges or pouches that can form in the lining of the large intestine (colon) as people get older. Simply having these pouches is called diverticulosis, and it usually causes no symptoms at all.

Diverticulitis is what happens when one or more of these pouches become inflamed or infected. This can cause persistent tummy pain, a change in bowel habits, and a high temperature. It is a different, more active problem than just having the pouches present.

Doctors use the term diverticular disease when the pouches cause symptoms such as intermittent lower abdominal pain or bloating, but without active infection. Diverticulitis is more specific: it refers to acute inflammation or infection of the pouches, which tends to cause more constant and severe pain.

The two are part of the same spectrum. Many people have painless diverticulosis for years, a smaller number develop ongoing diverticular disease, and some go on to have one or more episodes of diverticulitis.

The most common symptom is a constant, often severe pain low in the abdomen, frequently on the left side. Other symptoms can include a high temperature, feeling generally unwell, nausea, and a change in bowel habits such as constipation or diarrhoea. Some people notice blood in their stool.

Pain from diverticulitis tends to come on and stay, rather than coming and going. If the pouches bleed, you may pass a noticeable amount of fresh or dark blood from the back passage, which should always be checked by a doctor.

It is not fully understood why pouches form, but they become more common with age and are thought to be linked to pressure inside the bowel, possibly related to a low-fibre diet. Diverticulitis is believed to begin when a pouch becomes blocked or irritated, allowing inflammation or infection to develop.

Risk factors include older age, a diet low in fibre, being physically inactive, carrying excess weight, and smoking. Some medicines may also play a role. Having had one episode makes future episodes more likely.

A doctor will ask about your symptoms and examine your abdomen. Blood tests can show signs of infection or inflammation, and a stool sample may be taken to rule out other causes of similar symptoms.

Imaging, most often a CT scan, is the main way to confirm diverticulitis and to check for complications such as an abscess or perforation. A colonoscopy may be recommended once an acute episode has settled to look directly at the bowel lining and exclude other conditions.

Many milder episodes can be managed at home with rest, plenty of fluids, and simple pain relief such as paracetamol. Your doctor may suggest a lighter diet for a short time and, in some cases, a course of antibiotics if infection is present.

More severe diverticulitis may need hospital treatment with fluids and antibiotics given through a drip. If a complication develops, such as a collection of pus (abscess), a hole in the bowel (perforation), a blockage, or an abnormal connection between organs (fistula), a procedure or surgery may be needed.

Seek urgent medical help if you have severe or worsening abdominal pain, especially with a high temperature, persistent vomiting, or a swollen, very tender tummy. These can be signs of a serious complication such as perforation or peritonitis.

Heavy bleeding from the back passage, passing large clots, or feeling faint and unwell also need emergency assessment. It is always safer to be checked than to wait when symptoms are severe.

A diet rich in fibre from wholegrains, fruit, vegetables, and pulses, along with drinking enough fluids, staying active, and not smoking, is generally recommended to support bowel health and may reduce symptoms. Fibre is usually increased gradually rather than all at once.

Most people recover well from an episode of diverticulitis, particularly when it is mild. Some have repeated episodes over time, and a smaller number develop complications that need more intensive treatment. Ongoing healthy habits and follow-up with your doctor help keep the condition under control.