What Are The Complications Of Diverticular Disease?

Diverticular disease has seven recognised complications: bleeding, abscess, perforation with peritonitis, fistula, stricture, bowel obstruction and sepsis, according to NICE Clinical Knowledge Summaries. Most people with pouches in the bowel wall never experience any of them. Williams and colleagues report that 10% to 25% of people with diverticular disease develop acute diverticulitis, and about 15% of those go on to a complication such as an abscess, bleeding or perforation. Complications arrive most often at the first episode, not after years of repeat flares.

Our members describe the same surprise again and again. They manage a few flares, feel normal in between, and then a scan, a bleed or an emergency admission reveals something far bigger. Several tell us they never realised it could get this serious.

This article explains each complication in plain English, lists the warning symptoms of each, sets NICE guidance and published research beside what our members report, and shows how doctors grade and manage each one. It also covers the aftermath that few leaflets mention: scar tissue, stomas, anxiety and travel.

What Are The Main Complications Of Diverticular Disease?

NICE lists the complications below. The warning signs come from the same NICE page and describe what doctors find or what people notice. They help you describe a problem to a doctor and do not replace an examination.

How Common Are Complications Of Diverticular Disease?

Complications affect a minority of people, and the published figures vary with the group studied. The table gathers the numbers from the three sources behind this article.

The 15% and 25% figures for complicated diverticulitis differ, and neither paper explains the gap. The 25% figure of Imaeda and Hibi traces back to a 1969 review of 521 cases, while Williams and colleagues cite a different source. Treat both as estimates. The percentages for abscess, perforation and fistula add up to more than 100% in the Williams review, and this article reports them as the review gives them.

Timing matters as much as the numbers. Williams and colleagues report that complicated diverticulitis most often occurs at the first episode (fistulating disease is the exception) and that the risk of complications falls with further episodes. Age matters too. The mean age at admission for acute diverticulitis is 63, yet about 16% of admissions involve people under 45 (Imaeda and Hibi).

Why Do Complications Catch Members Off Guard?

Members who face a complication often describe years of ordinary flares first. One member in his late sixties described this pattern, and his scans later showed a perforation.

“Just a couple of simple flare-ups a year, which amoxicillin took care of in a couple of days. 99% of the time I feel normal.”

Gordon, Tampa

The same member then described what a routine CT scan found.

“Two hours later my doctor called and told me to go to the ER. They admitted me for a perforated colon.”

Gordon, Tampa

His story matches a second pattern in the sources. NICE explains that recurrent inflammatory episodes leave scar tissue (fibrosis) that narrows the bowel, which fits his later experience of failed colonoscopies. Other members describe a sudden escalation with no warning at all.

“This disease is no joke and can get out of hand without any warning.”

Callum, Winnipeg

Callum told the group he had lost over seven litres of blood and needed 12 transfusions. Other members replied with their own shock at how serious the condition can become.

“Truth is, I never really knew it could get this bad either. It’s pretty scary.”

Callum, Winnipeg

“I am so lucky, as I read others’ posts about hospital stays and operations. It has really opened my eyes.”

Ruth, Cork

“It’s a horrible thing to have. Unfortunately, lots of people just don’t realise how difficult it is.”

Marjorie, Bath

A second theme runs through the replies: members feel the medical profession underplays the condition.

“This disease is not taken seriously enough by the medical profession. I have been through hell and now have an ileostomy because of it.”

Bernadette, Glasgow

“I had three and was in hospital nine weeks. It is more serious than is spoken about.”

Trudy, Perth

These accounts are individual experiences. They show how wide the gap can be between a mild flare and a complication, and why members ask us to explain the difference.

What Does Each Complication Mean In Practice?

What Is A Diverticular Abscess?

An abscess is a pocket of pus beside the bowel. It is the most common complication of complicated diverticulitis, at about 70% according to Williams and colleagues. Williams and colleagues report that doctors treat a pericolic abscess without surgery, and that a radiologist draining a distant abscess through the skin is favoured over surgery for the grades they call Hinchey IIa and IIb (see the grading table below).

One member in her late sixties had an abscess alongside a perforation and had elective surgery afterwards.

“I’m 67 and had elective surgery after my last flare caused a perforation with an abscess. It was an open operation lasting five hours, and it went so well. I needed no pain medication once I got home after five days in hospital.”

Rosemary, Lincoln

What Happens In A Perforation With Peritonitis?

A perforation is a tear in the bowel wall. It can let pus or stool spill into the abdomen and cause peritonitis, an inflammation of the abdominal lining that can lead to sepsis. Imaeda and Hibi report that only 1% to 2% of people with acute diverticulitis have a perforation with purulent or faecal peritonitis, yet mortality in those cases approaches 20%. NICE cites a population-based cohort study in which people with perforation had a 4.5-fold increase in one-year mortality compared with the general population.

Perforations vary in size. Gordon’s doctors told him his was tiny.

“The next day I was told that it was so small that air could not pass through it.”

Gordon, Tampa

Hilary’s experience shows the other end of the range, and it shows how long the aftermath lasts.

“I had a diverticulitis bowel perforation with peritonitis, which led to emergency open surgery a few years ago. It resulted in a stoma bag, then a stoma reversal eight months later.”

Hilary, Exeter

What Is A Fistula, And How Would You Know?

A fistula is an abnormal channel between the bowel and another organ. NICE reports that the bladder is the most common destination and lists faeces, air or pus in the urine as the signs. NICE also cites a population-based cohort study in which people with a stricture or fistula had a 2.5-fold increase in one-year mortality compared with the general population. Imaeda and Hibi describe fistulas as a result of inflammation from acute diverticulitis.

Geraldine described her son’s journey. He had a five-hour open operation after a flare with an abscess and a micro perforation, and a fistula developed afterwards. She suspects a radiology procedure played a part. The three sources behind this article do not address that question, so the article reports it as her suspicion and not as a finding.

Another member linked repeated urinary problems to her condition.

“I keep getting urine infections because of diverticulitis. Really such a pain.”

Beryl, Chester

Urine infections have many causes, and NICE lists pus or air in the urine among the signs of a fistula. Anyone with recurring urinary symptoms alongside diverticular disease can raise the link with a GP.

Can Diverticulitis Narrow Or Block The Bowel?

Yes. NICE explains that fibrosis and stricture formation after recurrent inflammatory episodes narrow the bowel, and that obstruction follows when the narrowing becomes severe. Williams and colleagues note that surgical resection is usually needed for a fistula or a chronic obstruction caused by a stricture.

Gordon met this complication before his planned surgery.

“A colonoscopy failed due to a constriction. Scar tissue from flare-ups caused it.”

Gordon, Tampa

Judith described a complete blockage that needed surgery, which followed a perforation and sepsis the year before.

“I had surgery for a complete bowel blockage due to a perforation and sepsis the previous year.”

Judith, Hobart

How Serious Is Diverticular Bleeding?

Diverticular bleeding is a different kind of complication from the infective ones. NICE reports that it occurs in about 15% of people with diverticulosis, that one-third of bleeds are massive, and that 70% to 80% stop on their own. Williams and colleagues report that people with ongoing rectal bleeding or an unstable circulation should have an immediate CT angiogram, which finds the bleeding point and guides treatment through interventional radiology or endoscopy. Imaeda and Hibi add that more than half of bleeds in Western countries come from the right side of the colon, and that bleeding recurs in 14% to 38% of people.

Callum’s account shows what repeated bleeding looks like. He had bowel surgery with a temporary stoma bag, and the diverticular disease that remained kept bleeding.

“The complications came from the still active diverticulitis, which has now been constantly bleeding when it wants to. The bleeds have been extreme and led to over 7 litres of blood loss and 12 transfusions.”

Callum, Winnipeg

His doctors clipped the bleeding points and explained the limits of that approach.

“They clipped off nine different areas that were bleeding or could potentially bleed, but the surgeon said there are hundreds of areas that could possibly bleed. He compared it to potholes in a city: they can’t fix every single one in one sitting.”

Callum, Winnipeg

Another member, Dorothy, shared a different outcome from years ago. She said surgeons treated her husband’s bleeding point through a blood vessel in his leg, that he has not bled since, and that the team told them the method does not always work. Williams and colleagues list interventional radiology among the treatment routes after a CT angiogram, and individual results differ.

How Does Sepsis Fit In?

Sepsis is the body’s extreme response to infection. NICE links it to perforation and peritonitis and lists its signs as altered mental state, fast breathing, low blood pressure, fast heart rate, low temperature, no urine output or skin discolouration. NICE refers readers to its separate sepsis guidance for more detail. Judith’s account above shows it as one step in a longer chain of events.

How Do Doctors Grade And Treat Complicated Diverticulitis?

Doctors grade complicated diverticulitis on a CT scan with the modified Hinchey classification. Williams and colleagues report that the grade at the first presentation correlates with the risk of recurrence and further complications, and that it guides treatment.

Antibiotics play a narrower role than many members expect. Williams and colleagues report that several randomised trials found antibiotics did not help in uncomplicated diverticulitis, and that European and American guidelines advise antibiotics for people with complicated disease and for people with weakened immune systems. Your own clinician decides whether antibiotics suit your situation.

What Does Emergency Surgery Involve?

Williams and colleagues describe two main operations for the most serious grades. The Hartmann procedure removes the diseased sigmoid colon and creates an end colostomy. It carries a mortality rate of 2.6% to 7.3%, and a second major operation is needed to restore the bowel. The overall stoma closure rate is low. A sigmoid colectomy with a primary join (anastomosis), with or without a protective loop ileostomy, has been proposed as an alternative with a possible reduction in mortality. The review recommends the Hartmann procedure for Hinchey IV disease and for unstable patients, and it says surgeons may consider a primary join for Hinchey III. Imaeda and Hibi report that laparoscopic surgery for diverticular disease brings a shorter hospital stay and fewer complications than open surgery in a meta-analysis of non-randomised studies.

Members who have a stoma describe the waiting as the hardest part.

“I’ve had the bag for five weeks and I’m having a hard time dealing with it. They said it can be reversed in five or six months.”

Terence, Cardiff

Callum faces a wait of six to nine months for his reversal while the bleeding continues. Whether a stoma is temporary or permanent depends on the operation, the surgeon’s judgement and the person’s recovery.

Does Surgery Remove The Risk Of Further Problems?

Surgery does not eliminate diverticulitis or the symptoms that follow it. Williams and colleagues report an overall 20% risk of recurrence, with 8% of people having a further attack within the first year. The risk rises with each episode.

The same review reports that tummy pain persists in up to 25% of people after surgery. National guidelines advise against deciding on elective surgery by counting episodes. They recommend a case-by-case decision that weighs the person’s wishes, quality of life and other health conditions. Members make this decision with their surgeons, and they weigh it differently.

“Better to have the surgery at 69 than 79.”

Gordon, Tampa

That is one man’s judgement about his own situation, reached after a perforation and a narrowed bowel, and it does not apply to everyone. Williams and colleagues also note that elective surgery does not remove the possibility of recurrence.

What Happens After A Complication?

Complications leave marks that last beyond the hospital stay. Members describe scar tissue, adhesions, unpredictable bowel habits and anxiety. Hilary lives with all of these.

“That left me with a restricted bowel, loads of abdominal scar tissue and adhesions, and LARS.”

Hilary, Exeter

LARS stands for low anterior resection syndrome, a group of bowel function changes that some people experience after bowel surgery. Hilary also told the group that nobody had followed up her scar tissue and adhesions, and members who share that gap can ask their surgeon or GP who reviews them.

Williams and colleagues describe a further pattern. Up to 25% of people with diverticular disease have chronic, irritable bowel syndrome (IBS) like symptoms, and a retrospective study of over 1,000 people found those with diverticulitis were 4.7 times more likely to receive an IBS diagnosis. The authors call this possible “postdiverticulitis IBS” and say further work is needed.

Several members also describe a psychological toll. These are members’ own words, not diagnoses.

“It definitely causes great, overwhelming PTSD, what we’ve been through.”

Hilary, Exeter

“So much PTSD. So much.”

Jan, Dundee

“I have had some very hard situations with diverticulitis and I’m always on guard now.”

Dawn, Calgary

Can You Travel After A Complication?

Travel is the most common practical worry members raise after a serious episode. The three sources behind this article do not address flying, cabin pressure or travel insurance, so members’ answers below reflect personal experience and not medical evidence. A surgeon or GP can answer questions about your own bowel and your own operation.

Hilary started the discussion with a fear many members share.

“I want to go away on holiday, but I’m so scared to fly in case the scar tissue and adhesions cause pain or blockages. I’m petrified to do anything.”

Hilary, Exeter

Replies came from different experiences. One member reassured her about the plane itself and shared her own anxiety.

“I don’t think you have anything to worry about with cabin pressure. Planes are pressurised, otherwise we would all have issues. But I do understand travel anxiety. I never had it before, and now I do because of diverticulitis.”

Joan, Columbus

Another member who survived a long hospital stay chose to holiday closer to home.

“After the coma and four and a half months in hospital with a perforated bowel, the aftercare, too many appointments and insurance through the roof, I decided to stay on home ground this year and booked a few mini holidays.”

Lorraine, Leeds

Judith has flown several times since her surgery. She travels with antibiotics that her doctor prescribed for diverticulitis, and she described her experience abroad.

“I have flown several times with no issues, except an infection on returning from a trip abroad, which I was told was possibly due to a change in diet.”

Judith, Hobart

Whether to carry antibiotics is a decision for the prescriber, and the research above shows that antibiotics suit complicated disease and weakened immunity but not routine uncomplicated flares. Beryl added a practical point about insurance.

“I’ve just got insurance for a trip to France, and I double-checked that I had disclosed all my conditions, just in case.”

Beryl, Chester

What Raises The Risk Of A Complication?

Researchers have not identified a single trigger for complications. Williams and colleagues describe several associations, and these show a link and do not prove that one thing caused another. Our article on what causes diverticular disease explains how pouches form and why some become inflamed.

Imaeda and Hibi add that complications occur more often in left-sided diverticulitis, which is the usual pattern in Western countries. People who take any of the medicines above for another condition should speak to their GP, pharmacist or specialist before changing anything.

Family history also appears in our group, though the sources behind this article do not measure it for complications.

“My granny, dad, aunt, myself, sister, then two sons have diverticulitis, all in varying degrees of seriousness. Never underestimate this illness.”

Elaine, Swansea

When Should You Seek Urgent Medical Help?

The NHS advises contacting a GP as soon as possible if you have symptoms of diverticular disease or diverticulitis. It also says people who already have a diagnosis usually do not need to contact a GP for symptoms they can treat at home, but they should seek immediate medical advice for any bleeding or severe pain. The NICE signs in the table below match the complications described above. Doctors confirm which one applies, and nobody can diagnose a complication from a list.

Our guide on when to go to the ER with diverticulitis walks through the decision in more detail, and our article on whether diverticulitis is a serious problem puts the risks in context. For a day-to-day picture, read our guide to the symptoms of a diverticulitis flare-up.

Frequently Asked Questions

Which Complication Is The Most Common?

An abscess is the most common complication of complicated diverticulitis, at about 70% in the Williams review. Bleeding affects 5% to 15% of people with diverticulosis.

Can Diverticular Bleeding Stop By Itself?

Yes in most cases. NICE reports that bleeding stops spontaneously in 70% to 80% of cases. About one-third of bleeds are massive and need emergency transfusion, and Imaeda and Hibi report that bleeding recurs in 14% to 38% of people. Callum’s experience shows that some bleeds do not settle.

Do Complications Only Happen At The First Flare?

No, but most do. Williams and colleagues report that complicated diverticulitis occurs most often at the first presentation, with fistulating disease as the exception. Gordon had ten years of flares before his perforation and narrowing, which shows that individual patterns differ.

Is A Stoma Always Permanent?

No. Hilary’s stoma was reversed eight months after her operation, and Terence was told to expect five or six months. Williams and colleagues note that the Hartmann procedure needs a second major operation to restore the bowel and that the overall closure rate is low. Your surgeon explains which outcome applies to your operation.

Can Younger People Develop Complications?

Yes. Williams and colleagues report that diverticular disease is rising rapidly in younger age groups, and Imaeda and Hibi report that about 16% of admissions for acute diverticulitis involve people under 45.

Does Everyone With A Complication Need Antibiotics?

No. European and American guidelines advise antibiotics for complicated disease and for people with weakened immune systems, and they advise against routine antibiotics in uncomplicated diverticulitis in people with healthy immune systems. A clinician makes that decision after assessing you.

Do Complications Differ Around The World?

Yes. Imaeda and Hibi report that diverticulitis occurs mostly on the left side of the colon in Western countries and mostly on the right side in Asian countries. Complications occur more often in left-sided diverticulitis. In Western countries, more than half of diverticular bleeds come from the right colon.

Can Anyone Avoid Complications?

Nobody can guarantee prevention. Williams and colleagues describe vigorous activity, a healthy body mass index and a high-fibre diet as associated with a lower risk of diverticulitis, and they note that targeted preventive measures have proved difficult to establish. Discuss your own situation with your GP.

More Reading

What Are The Symptoms of a Diverticulitis Flare Up?

Ultimate Guide to Diverticulosis and Diverticulitis

Can Stress Trigger Diverticulitis Symptoms?

Is Exercise Good Or Bad For Diverticulitis?

The Best 10 Food and Symptoms Diaries, Journals and Apps for Understanding Diverticulitis

Key Takeaways

• • Diverticular disease has seven recognised complications: bleeding, abscess, perforation with peritonitis, fistula, stricture, bowel obstruction and sepsis.
  • Most people with diverticulosis never develop a complication. About 15% of people with diverticulitis do in the Williams review, and about 25% in the Imaeda and Hibi review.
  • Most complications occur at the first episode of diverticulitis, and the risk falls with later episodes.
  • Abscess is the most common complication of complicated diverticulitis, and perforation with peritonitis carries a mortality approaching 20% in the Imaeda and Hibi review.
  • Diverticular bleeding stops without treatment in 70% to 80% of cases, but it recurs in 14% to 38% of people.
  • Surgery for a complication does not remove the chance of further problems, and guidelines advise deciding on elective surgery case by case.
  • Members describe scar tissue, stomas, anxiety and travel worries after a complication, and several say the condition is not spoken about enough.
  • Seek medical advice promptly for bleeding, severe pain, or any of the warning signs above.

Sources

• • NICE Clinical Knowledge Summaries. Diverticular disease: What are the complications? Last revised December 2023.
  • Imaeda H, Hibi T. The Burden of Diverticular Disease and Its Complications: West versus East. Inflammatory Intestinal Diseases, 2018.
  • Williams S, Bjarnason I, Hayee B, Haji A. Diverticular disease: update on pathophysiology, classification and management.
  • Diverticular disease and diverticulitis.

If a complication has changed how you live, you are not alone. Share your own experience in our Diverticulitis Club Facebook group, join the conversation in our forums, or track your own patterns in the Food And Symptoms Diary. Reading what other members go through will not replace medical care, but it shows you that other people have faced the same fears.

Disclaimer: This article does not constitute medical advice. Diverticulitis affects everyone differently. Always seek advice from a qualified medical practitioner about your own symptoms, diagnosis and treatment.