Diverticulitis is characterised by acute inflammation and infection of diverticula.
Diverticulitis is a common presentation on any surgical take. It typically presents with abdominal pain and fevers.
Terminology is key to understanding diverticulitis and its associated diseases:
Diverticulosis most commonly affects the sigmoid colon but may occur anywhere in the gastrointestinal tract. Right sided colonic disease is more common in those of Asian descent.
Diverticulosis affects around 80% of those aged 85 or older.
The incidence of diverticulosis increases with advancing age. It is rare before 40, above the age of 45 it affects 5-10% and above the age of 85 it will affect up to 80%.
The majority of individuals with diverticulosis will remain asymptomatic. However for patients with diverticulosis the lifetime risk of acute diverticulitis is 4-25%.
A number of risk factors are associated with diverticulosis and acute diverticulitis.
Diverticula are thought to occur due to raised intra-luminal pressures and abnormal colonic motility.
Diverticula occur when the colonic mucosa (and submucosa) protrudes through the muscular layer (muscularis externa) so to only be covered by the serosa. They appear to occur in weak areas, at points where vasa recta penetrate the muscularis externa.
Diverticula become increasingly common with advancing age. Though it is not known exactly why they occur, it is thought to be related to raised intra-luminal pressures and abnormal colonic motility.
Not everyone with diverticula develop diverticulitis, it is estimated that patients with diverticulosis have a 4-25% lifetime risk of acute diverticulitis. The exact cause of diverticulitis is still unknown although a number of theories have been posited.
It is thought to occur due to perforation of diverticula, this may be microscopic (and without signs like free air in the abdomen) or macroscopic. The perforation is said to occur due to food particles or raised intra-luminal pressures.
There is a wide-range of clinical presentations. Microscopic perforations may result in mild localised inflammation which is quickly walled off by mesentery/omentum. In more severe cases generalised purulent or faecal peritonitis occurs.
Further complications can occur. Prolonged inflammation between the colon and a neighbouring organ (e.g. bladder) may result in a fistula. Recurrent episodes of diverticulitis may result in diverticular strictures and obstruction.
Patients often present with abdominal pain, fevers and tenderness in the left iliac fossa.
CT abdomen and pelvis is the imaging modality of choice to diagnose diverticulitis.
CT Abdomen and pelvis: The diagnostic modality of choice. Helps to assess severity (along with clinical signs), prognosis and identify complications. Should be with contrast unless contraindicated.
The modified Hinchey classification can be used to help guide the need for surgical intervention.
Diverticulitis presents with a spectrum of severity which dictates management.
Admit any patient who is elderly, co-morbid, unwell, in significant pain, peritonitic or has evidence of perforation or abscess formation on CT. If features of severe systemic infection are present, urgently arrange senior review, complete the sepsis six bundle and promptly refer to surgeons.
Commence IV antibiotics, co-amoxiclav is normally first line (in the absence of penicillin allergy). The patient should be nil by mouth until surgical review and commenced on intravenous fluids.
Surgical management may be required in those presenting with severe complicated disease or who fail to respond to conservative management. Interventions include radiologically guided drainage of abscess or laparoscopic washout. In more severe cases a Hartmann’s procedure may be required.
There is a risk of underlying malignancy and as such outpatient colorectal follow-up and colonoscopy (if appropriate, and after acute inflammation has settled) should be arranged at discharge. Those who have undergone resection should receive colorectal follow-up.
Most advise a high-fibre diet (and to avoid constipation) though the evidence that this reduces attacks is not clear.
Elective surgical intervention for those with repeated attacks should be discussed with a colorectal consultant.
Acute diverticulitis and diverticula are associated with a number of complications.
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