What Is Diverticulitis?


Diverticulitis is a complication that occurs when small pouches in your gut, called diverticula, become inflamed or infected. These pouches can develop in weak spots of the colon walls, being more commonly found in the sigmoid colon (the lower part of the colon). Diverticulitis can result in severe abdominal pain, nausea, diarrhoea, constipation, and vomiting. If the diverticula becomes inflamed, the affected individual may require immediate medical attention to avoid any serious health consequences.1

Causes of diverticulitis

Diverticulitis is caused by the inflammation or infection of one or more diverticula, which are small, bulging pouches that can form in the mucosal lining of the digestive system. The exact causes of inflammation and infection that lead to diverticulitis are varied and may not always be fully understood. Physical damage to diverticula, such as a tear in the lining of the colon, may start an inflammatory response. These tears may occur when passing hard stools. Additionally, diverticula formed in the lining of the gut act as an effective hiding place for bacterial growth, allowing harmful bacteria (pathogens) to invade surrounding tissues and evade the immune system. Accumulation of bacteria results in the swelling of the diverticula. Some studies suggest that the cytomegalovirus (CMV infection) may also be a significant contributor to inflammatory responses that lead to diverticulitis.1

Signs and symptoms of diverticulitis

Patients with diverticulitis may present with general gut-related symptoms that can make the condition difficult to distinguish from other conditions.The following are the most common symptoms of diverticulitis:

  • Persistent or constant abdominal pain (mostly on the left side)
  • Nausea
  • Vomiting
  • Rectal bleeding
  • Constipation
  • Diarrhoea
  • Palpable colon (a colon that can be felt by an examiner’s fingers)
  • Fever

Diagnosis of diverticulitis

Diverticulitis is usually diagnosed by taking a patient’s medical history, performing a physical examination and conducting diagnostic tests. The following are some of the common tests used for the diagnosis of diverticulitis:2

  • Blood tests: A full blood count (FBC) may be ordered by your health provider to check for signs of infection, such as the presence of an elevated white blood cell count
  • Urine tests: A urinalysis may be performed to rule out urinary tract infections, which can cause a patient to present with similar symptoms
  • Stool tests: Stool tests may be done to check for the presence of blood in the stool
  • Imaging tests: Imaging tests, such as CT scans or ultrasounds, can help visualise the inflamed or infected diverticula and evaluate the extent of aninfection
  • Colonoscopy: A colonoscopy may be performed to rule out other conditions that can cause similar symptoms, such as inflammatory bowel disease or colon cancer
  • Flexible sigmoidoscopy: A flexible sigmoidoscopy may be performed to visualise the lower part of the colon and rectum

Management and treatment of diverticulitis 

If your doctor suspects the presence of diverticulitis, they may recommend different treatment options, depending on the severity of the condition. Patients affected by uncomplicated diverticulitis, where inflammation or infection of the diverticula is not severe and has not caused any permanent organ damage,  are typically managed with antibiotics and painkillers. Patients are advised to implement a low-fibre diet to allow their colon to heal and to prevent the recurrence of tears that can reinstate an inflammatory response. In complicated diverticulitis, where inflammation has become severe enough to cause secondary organ damage, a surgical procedure may be recommended to remove parts of the affected colon (colectomy).2

Risk factors

  • Ageing: Diverticulitis is more common in people over the age of 50
  • Low-fibre diet: A diet that lacks fibre can cause constipation, increasing pressure in the colon that can lead to diverticula formation
  • Obesity: Gaining weight can increase the risk of diverticulitis
  • Genetics: Although diverticulitis is thought to occur randomly, there may be a possibility of a genetic component to the development of diverticulitis
  • Sedentary lifestyle: A sedentary lifestyle can contribute to the development of diverticulitis
  • Smoking: Smoking has been linked to an increased risk of diverticulitis
  • Nonsteroidal anti-inflammatory drugs (NSAIDs): The use of NSAIDs, such as ibuprofen and aspirin, may increase the risk of diverticulitis


Most of the time, diverticulitis is uncomplicated. However, in severe cases, the condition can lead to dangerous complications, which include:3

  • Abscesses: Pockets of pus can form in the wall of the colon or in the surrounding tissues
  • Perforations: The inflamed or infected diverticula can rupture, causing faecal matter to leak into the abdominal cavity. This canlead to a serious infection known as peritonitis
  • Fistulas: An abnormal tunnel can form between the colon and other organs, such as the bladder, the vagina, or the skin
  • Bowel obstruction: The repeated inflammation and healing of the diverticula can cause scarring and narrowing of the colon, making it difficult for waste to pass through
  • Bleeding: Rarely, the inflamed diverticula can bleed, leading to rectal bleeding and anaemia


What is the difference between diverticulitis and diverticulosis?

Diverticulosis and diverticulitis are both related conditions that affect the large intestine or colon. Diverticulosis is a condition in which small, bulging pouches (diverticula) form in the lining of the colon. Diverticulitis, on the other hand, is a more serious condition that occurs when those pouches become inflamed or infected.

Diverticulosis is a common condition, especially in older adults, and often causes no symptoms. However, in some cases, diverticulosis can cause bloating, constipation, diarrhoea, or abdominal pain.

Diverticulitis is instead a more serious condition that can cause severe abdominal pain, nausea, fever, and changes in bowel movements. It's worth noting that diverticulitis can sometimes be a complication of diverticulosis, but not everyone with diverticulosis will develop diverticulitis.4

How common is diverticulitis?

Generally, diverticulosis is quite common among the population while diverticulitis is relatively uncommon. It is estimated that diverticulitis affects around 4% of individuals with diverticulosis. Moreover, diverticulosis usually does not occur before the age of 40. This suggests that ageing is a significant risk factor in the development of the condition. Studies have shown that among people who are above the age of 50, diverticulitis is more prevalent in females than in males.

How can I prevent diverticulitis?

While there is no guaranteed way to prevent diverticulitis, there are steps you can take to reduce your risk of developing this condition or having it occur again. Here are some lifestyle changes you can implement to help prevent diverticulitis:

  • High-fibre diet: Eating a diet that is high in fibre can help prevent constipation and reduce the risk of developing diverticula. It is best to add plenty of fruits, vegetables, whole grains, and legumes to your diet
  • Stay hydrated: Drinking plenty of water and fluids can help keep your stools soft and prevent constipation
  • Exercise regularly: Regular physical activity can help maintain a healthy weight and promote regular bowel movements
  • Quit smoking: Smoking has been associated with an increased risk of diverticulitis, so avoiding smoking can help reduce your risk of developing this condition
  • Manage stress: Chronic stress can have a negative impact on your digestive system. Hence, finding ways to manage stress, such as through meditation or yoga, can help you prevent diverticulitis l

When should I see a doctor?

It is advised to seek medical attention if you experience persistent, unexplained pain in the abdominal region, fever, diarrhoea, or constipation. Your doctor may help to evaluate your condition and recommend treatment to prevent any further complications.


Diverticulitis is a condition where small pouches, called diverticula, form in the wall of the colon and become inflamed or infected. They are prone to form in  the sigmoid (lower) colon and can cause uncomfortable symptoms such as abdominal pain, fever, nausea, vomiting, constipation, and diarrhoea. In the majority of cases, diverticulitis can resolve with little to no treatment. However, it is important to seek medical advice about your condition to avoid any complications. Changes in diet and lifestyle, along with medical treatment, can aid in alleviating your symptoms and improving your gut health.


  1. Strate LL, Morris AM. Epidemiology, Pathophysiology, and Treatment of Diverticulitis. Gastroenterology. 2019 Apr;156(5):1282–98. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6716971/ 
  2. Kishnani S, Ottaviano K, Rosenberg L, Arker SH, Lee H, Schuster M, et al. Diverticular Disease—An Updated Management Review. Gastroenterology Insights. 2022 Sep 30;13(4):326–39. https://www.mdpi.com/2036-7422/13/4/33 
  3. Onur MR, Akpinar E, Karaosmanoglu AD, Isayev C, Karcaaltincaba M. Diverticulitis: a comprehensive review with usual and unusual complications. Insights into Imaging [Internet]. 2016 Nov 22;8(1):19–27. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5265196/figure/Fig6/ 
  4. Thompson AE. Diverticulosis and Diverticulitis. JAMA. 2016 Sep 13;316(10):1124. https://jamanetwork.com/journals/jama/fullarticle/2552211 
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Sadaf Ahmed

Master of Science - MSc, Physiology, Clinical & Molecular Hematology, Karachi University, Pakistan

Sadaf is an experienced writer who creates a quality and well-researched scripts particularly related to Health Sciences.

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