There are no known causes. Recently it is likely that low-fiber diet is one of the risk factors. Less fiber increases constipation, and results in harder compact stools which require more pressure to push them along the colon. A long period of high pressure within the colon could lead to the formation of the sacs.
 

Basically there are no shown symptoms in non-complication cases. However, some might experience bloating, constipation or diarrhea, and lower abdominal cramps. Mostly, it may be found unexpectedly after performing barium enema, sigmoidoscopy, or colonoscopy. Patients without symptoms shown are likely not to experience them at all, only 15-25% could experience bleeding from pockets vessels.
In case of diverticulitis, patients might experience the following symptoms:

• Abdominal pain, usually in the lower left area
• Nausea, vomit
• Constipation or diarrhea  
• Fever, shivering

However, with the right diagnosis and antibiotic administration, most of the cases are cured. There are a small number of cases that complications occur.
 

• Abscess formation
• Formation of a tract or tunnel to another organ or the skin (called a fistula)
• A blockage of the colon
• Inflammation of abdominal lining wall 
• Sepsis
• Bloody or dark stool without other symptoms

Complications could lead to complicated and prolonged treatment.
 

As mentioned above that this disease is likely to be found unexpectedly, thus the diagnosis might include:

• Barium enema
• Sigmoidoscopy
• Colonoscopy
• Computerized tomography scan or CT scan

• Diverticulosis does not need any treatment.
• Eating a high fiber diet to soften the stool could reduce complications.
• Treatment of diverticulitis depends on severity:
  • In mild cases, oral medication could cure the disease.
  • In more severe cases, patients might need hospitalization, intravenous medication, or surgery.
• In most cases, bleeding disappear by itself. However, there are cases that need colonoscopic intervention or surgery.