Diverticulitis: Symptoms, Types, Causes and Treatment

Diverticulitis is a common digestive condition that can dramatically impact quality of life. Although it often starts with small pouches (diverticula) in the colon, its symptoms, causes, and treatments are more complex than many realize. As research advances, our understanding of diverticulitis continues to evolve—from its subtle symptoms and risk factors, to the range of therapeutic options now available. Whether you’re newly diagnosed, caring for a loved one, or simply curious, this guide will give you a comprehensive and evidence-based overview of diverticulitis.

Symptoms of Diverticulitis

Diverticulitis symptoms can range from mild discomfort to severe, life-threatening complications. Recognizing the early signs is crucial for timely diagnosis and effective management. While many people with diverticulosis (the presence of diverticula) remain symptom-free, the onset of diverticulitis marks a shift—one that often brings pain and changes in bowel habits to the forefront.

Symptom	Description	Severity Range	Source(s)
Abdominal pain	Often left lower quadrant; can be right-sided in some populations	Mild to severe, persistent	3 4 5 6
Fever	Low-grade, sometimes elevated	Mild to high	4 5 6
Bowel changes	Diarrhea, constipation, or both	Mild to moderate	3 4 5
Nausea	May occur without vomiting	Mild	4 5 6
Abdominal distention	Feeling bloated or swollen	Mild to moderate	1 3 4
Urinary symptoms	Dysuria, frequency	Mild (if present)	4
Complications	Abscess, fistula, peritonitis	Severe, urgent	3 4 9

Table 1: Key Symptoms of Diverticulitis

Abdominal Pain: The Cardinal Symptom

Most commonly, diverticulitis presents with abdominal pain. In Western populations, pain typically localizes to the left lower quadrant (LLQ), reflecting the usual location of diverticula in the sigmoid colon. However, right-sided or suprapubic pain can also occur, especially in younger people or in certain ethnic groups 4 5. The pain is generally constant, develops over hours to days, and may worsen with movement 4.

Systemic Symptoms

Fever is a common sign, often accompanied by an elevated white blood cell count and increased inflammatory markers such as C-reactive protein (CRP) 4 5 6. Nausea is frequent, though vomiting is less common 4 5. Some patients experience loss of appetite and malaise.

Changes in Bowel Habits

Diverticulitis can cause diarrhea, constipation, or an alternation between the two. These changes are often subtle and may be overlooked, but persistent alteration in bowel habits should prompt evaluation 4.

Urinary and Other Symptoms

Because the inflamed colon can be close to the bladder, urinary symptoms such as dysuria or increased frequency may occur. More severe complications—like abscesses, fistulas (abnormal connections to the bladder or vagina), or peritonitis—manifest with more dramatic symptoms, including severe pain, rigidity, and signs of sepsis 4 9.

Chronic and Post-Diverticulitis Symptoms

Some patients, even after treatment or surgery, may continue to experience symptoms such as cramping, bloating, diarrhea, constipation, or a condition resembling irritable bowel syndrome (IBS) 1 2. These persistent symptoms can affect quality of life and highlight the chronic nature of diverticular disease for some individuals.

Types of Diverticulitis

Not all cases of diverticulitis are alike. The disease can be classified based on severity, complications, and chronicity. Understanding these types helps guide treatment and anticipate possible outcomes.

Type	Features	Typical Management	Source(s)
Uncomplicated	Localized inflammation, no complications	Conservative, outpatient	3 4 6 8
Complicated	Abscess, fistula, perforation, obstruction	Hospitalization, possible surgery	3 4 9 18
Recurrent	Multiple episodes, can be mild or severe	Individualized, may consider surgery	2 8 19
Chronic/Smoldering	Persistent symptoms, low-grade inflammation	Tailored, may need surgery or medical therapy	2 7 8

Table 2: Types of Diverticulitis

Uncomplicated Diverticulitis

This is the most common form, involving localized inflammation of the colon wall and surrounding tissues, but without abscess, perforation, or other serious complications. Most cases are mild to moderate and can often be managed on an outpatient basis 3 4 6.

Complicated Diverticulitis

About 12% of diverticulitis cases are complicated, featuring abscess formation, fistulas (abnormal connections to other organs), bowel obstruction, or free perforation leading to peritonitis 4 9 18. These cases require prompt medical attention and often hospitalization.

• Abscess: Localized collection of pus, may need antibiotics or drainage 4 18.
• Perforation/Peritonitis: Life-threatening, requires emergency surgery 3 4 18.
• Fistula: Abnormal connection, usually to the bladder or vagina, resulting in unusual symptoms like passage of air or stool in urine or vagina 4 9.
• Obstruction: Due to swelling or scarring, can cause severe constipation and abdominal distention 4 9.

Recurrent Diverticulitis

Roughly 20% of patients experience one or more recurrences within 10 years 4 19. Recurrences can range from mild to severe, and management decisions are now more nuanced—surgery is no longer automatically recommended after a certain number of episodes 19.

Chronic or Smoldering Forms

Some individuals develop persistent, low-grade symptoms even after an acute attack. This chronic form can be difficult to distinguish from irritable bowel syndrome or inflammatory bowel disease and may require individualized therapy 2 7 8.

Causes of Diverticulitis

The exact causes of diverticulitis remain a subject of research and debate, but several risk factors and mechanisms have been identified. These include dietary, lifestyle, genetic, and physiological contributors, as well as emerging evidence about the role of inflammation and gut bacteria.

Cause	Mechanism/Description	Modifiable?	Source(s)
Low fiber diet	Alters stool bulk, affects colon wall	Yes	4 11 13
Obesity	Increases risk and inflammation	Yes	4 6 19
Smoking	Linked to higher risk	Yes	4 6
NSAIDs, steroids	Medications increasing risk	Yes	4 6 13
Genetics	Family history, gene associations	No	4 10 19
Age	Risk rises with age	No	4 6 13
Microbiome changes	Altered gut bacteria, dysbiosis	Partially	2 11 12 19
Chronic inflammation	Low-grade mucosal inflammation	Partially	2 12 13 14

Table 3: Causes and Risk Factors for Diverticulitis

Dietary and Lifestyle Factors

For decades, a low-fiber diet has been considered the main culprit. Fiber adds bulk to stool and may reduce pressure inside the colon, thus preventing diverticula from forming or becoming inflamed. Recent studies, however, suggest the relationship between fiber and diverticulitis is more nuanced, and other dietary patterns (such as high red meat intake) and lifestyle factors (like physical inactivity and obesity) also play significant roles 4 6 19.

Medications

Regular use of non-aspirin NSAIDs, corticosteroids, and opiates has been strongly linked to increased risk of diverticulitis, especially complicated forms, possibly due to their effects on gut integrity and immune response 4 6 13.

Genetics and Age

Family history and genetic factors account for up to 50% of a person's susceptibility to diverticular disease. Specific gene variants have recently been identified, underlining a substantial hereditary component 4 10 19. Age remains a powerful risk factor, with prevalence increasing dramatically after age 50 4 6 13.

Microbiome and Chronic Inflammation

Emerging research highlights the role of gut microbiota and low-grade inflammation in the development and recurrence of diverticulitis. Altered bacterial populations can disrupt the immune balance in the colon, leading to chronic inflammation and, eventually, acute diverticulitis 2 11 12 19. This has opened new discussions about whether diverticulitis is, in part, an inflammatory bowel disease 12.

Other Contributing Factors

• Physical inactivity
• Obesity
• Smoking
• Vitamin D deficiency
• Certain medications

All have been linked to either an increased risk of diverticulitis or worse outcomes 4 6 19.

Treatment of Diverticulitis

Diverticulitis treatment has shifted dramatically in recent years, moving from a one-size-fits-all approach to more personalized and evidence-based care. Today, treatment depends on the type and severity of the disease, presence of complications, and patient preferences.

Treatment	Indication	Inpatient/Outpatient	Source(s)
Bowel rest/diet	Mild, uncomplicated cases	Outpatient or inpatient	3 4 6
Antibiotics	Historically for all; now mainly for complicated or select cases	Both	3 4 6 15 16 17
Pain management	All cases	Both	3 4
IV fluids	Moderate/severe or hospitalized	Inpatient	3 4 6
Percutaneous drainage	Abscess >3 cm	Inpatient	4 18
Surgery	Complicated, refractory, or recurrent cases	Inpatient	1 3 4 8 18 19
Lifestyle modification	Prevention, recurrence	Outpatient	3 4 19
Probiotics/mesalamine	Selected chronic/recurrent cases	Outpatient	2 13 14

Table 4: Treatment Approaches for Diverticulitis

Uncomplicated Diverticulitis

• Conservative management (bowel rest, fluids, pain control) is now the mainstay for mild cases, with evidence showing that antibiotics may not be necessary for all patients 3 4 6 15 16 17.
• Outpatient treatment is often safe and effective for stable patients without severe symptoms or comorbidities.

Antibiotics: Not Always Required

• Recent clinical trials and guidelines suggest that in mild, uncomplicated cases, antibiotics do not speed recovery or reduce complications and may be omitted 3 4 6 15 16 17.
• Antibiotics remain standard for complicated diverticulitis or when risk factors for poor outcomes exist.

Hospitalization and Advanced Care

• Patients with severe symptoms, signs of peritonitis, or complicated disease are hospitalized for close monitoring, intravenous fluids, and often IV antibiotics 3 4 18.
• Abscesses larger than 3 cm are typically treated with CT-guided percutaneous drainage, sometimes in combination with antibiotics 4 18.

Surgery

• Indications for surgery include failure of medical therapy, perforation, generalized peritonitis, fistula, obstruction, or recurrent/persistent symptoms affecting quality of life 1 3 4 8 18 19.
• Minimally invasive (laparoscopic) surgery is increasingly preferred, offering shorter hospital stays and fewer complications than open surgery 3 13.
• Elective (planned) surgery is now individualized and not based solely on the number of attacks 19.

Chronic and Recurrent Diverticulitis

• Persistent symptoms after treatment or surgery are increasingly recognized; up to 25% of patients may continue to experience pain, constipation, or diarrhea 1 2.
• Gut-directed therapies such as probiotics or mesalamine may help in some chronic cases, especially where low-grade inflammation is present 2 13 14.

Prevention and Lifestyle Modification

• Increasing dietary fiber, physical activity, maintaining a healthy weight, and avoiding smoking are all recommended to reduce the risk of recurrence 3 4 19.
• There is no evidence that avoiding nuts, corn, or seeds reduces risk 4.

Conclusion

Diverticulitis is a complex and evolving condition that can affect anyone, but is more common as we age. Early recognition of symptoms, understanding the different types and causes, and knowing the range of treatment options are crucial for effective management.

Key Points:

• Symptoms commonly include left lower abdominal pain, fever, and bowel changes; complications can be severe.
• Types include uncomplicated, complicated, recurrent, and chronic forms, each requiring tailored management.
• Causes are multifactorial, involving diet, lifestyle, genetics, age, medications, and gut microbiome changes.
• Treatment has shifted toward less aggressive approaches for uncomplicated cases, with surgery reserved for complicated or persistent disease. Lifestyle modification is key to prevention.

By staying informed and working closely with healthcare providers, patients can manage diverticulitis more effectively, reduce the risk of recurrence, and maintain a better quality of life.