Pathogenesis and Management of Acute Colonic Diverticulitis
An algorithm for the investigation and management of patient with acute diverticulitis based on current clinical practice guidelines is shown in Figure 2. Bed side investigations should include a urine analysis to exclude urinary tract infection and pregnancy in women of child-bearing age, remembering that blood and protein in the urine may reflect bladder/ureter inflammation secondary to diverticulitis. Blood tests should include a full blood count, urea and electrolytes along with a C-reactive protein and amylase or lipase (as local policy dictates). The clinical triad of left lower quadrant pain, fever and leucocytosis is often quoted in the diagnosis of acute diverticulitis; however, precise data on its accuracy are lacking. A recent retrospective study using HMO records in California found leukocytosis in 58.5% and temperature >37.5 °C in 30.1% of patients presenting to the emergency department with acute diverticulitis. However, the triad of abdominal pain, fever and leukocytosis was found in only 47% of those with severe findings on CT (abscess, perforation), indicating an unacceptable sensitivity, despite specificity of 95.2%. It is currently recommended that either CT or US scanning (depending on local expertise) should be undertaken within 72 h of admission to confirm the clinical diagnosis of acute diverticulitis and exclude any associated complications. This position has been challenged and authors have attempted to identify severe cases that may benefit from imaging and reduce patient radiation exposure and health care costs in those with uncomplicated diverticulitis. The Longstreth study found severe CT findings in just 3.8%, of those with lower rather than generalised abdominal pain and no fever or leukocytosis, suggesting that for such patients, a wait and see approach might be cost effective without CT. The optimal imaging modality for patients with acute diverticulitis was recently the subject of a Cochrane review, which commented on how few high-quality studies there were. The review reported that ultrasound had a sensitivity of 84–99%, but a specificity of as low as 57% and as high as 100%, suggesting considerable local variability in expertise. Typical ultrasound appearances are of a thickened loop of bowel with a target-like appearance. The same review found a wide range of sensitivities for CT varying from 65% to 97% with a specificity of 77–100%. The typical findings on CT are pericolonic fat stranding, bowel wall thickening and diverticular. Additional findings may include abscess, free fluid, free air, an inflamed diverticulum or the arrowhead sign in which contrast material shows an arrowhead configuration at the ostia of an inflamed diverticulum (Figure 3 shows an inflamed sigmoid diverticular segment with associated abscess). Studies comparing the two modalities are limited and the review concluded that it was difficult to draw firm conclusions, especially as the quality of CT has improved so much recently. The recent ACPGBI position statement concluded that the choice between the two modalities should be made on local expertise. The recent American College of Radiology Guidelines suggested CT in the first instance as US was limited by operator expertise. Ultrasound, however, may have a role in premenopausal women and the young to reduce radiation exposure. Barium enema sensitivity varies from 29% to 93% with specificity of 50–100%, but its inability to visualise extra-luminal complications means that it is no longer used acutely.
(Enlarge Image)
Figure 2.
Investigation and treatment algorithm for patients presenting with suspected acute diverticulitis based on current guidelines.
(Enlarge Image)
Figure 3.
CT scan of acute sigmoid diverticulitis with associated abscess formation (white arrow), which required surgical resection.
Investigations
An algorithm for the investigation and management of patient with acute diverticulitis based on current clinical practice guidelines is shown in Figure 2. Bed side investigations should include a urine analysis to exclude urinary tract infection and pregnancy in women of child-bearing age, remembering that blood and protein in the urine may reflect bladder/ureter inflammation secondary to diverticulitis. Blood tests should include a full blood count, urea and electrolytes along with a C-reactive protein and amylase or lipase (as local policy dictates). The clinical triad of left lower quadrant pain, fever and leucocytosis is often quoted in the diagnosis of acute diverticulitis; however, precise data on its accuracy are lacking. A recent retrospective study using HMO records in California found leukocytosis in 58.5% and temperature >37.5 °C in 30.1% of patients presenting to the emergency department with acute diverticulitis. However, the triad of abdominal pain, fever and leukocytosis was found in only 47% of those with severe findings on CT (abscess, perforation), indicating an unacceptable sensitivity, despite specificity of 95.2%. It is currently recommended that either CT or US scanning (depending on local expertise) should be undertaken within 72 h of admission to confirm the clinical diagnosis of acute diverticulitis and exclude any associated complications. This position has been challenged and authors have attempted to identify severe cases that may benefit from imaging and reduce patient radiation exposure and health care costs in those with uncomplicated diverticulitis. The Longstreth study found severe CT findings in just 3.8%, of those with lower rather than generalised abdominal pain and no fever or leukocytosis, suggesting that for such patients, a wait and see approach might be cost effective without CT. The optimal imaging modality for patients with acute diverticulitis was recently the subject of a Cochrane review, which commented on how few high-quality studies there were. The review reported that ultrasound had a sensitivity of 84–99%, but a specificity of as low as 57% and as high as 100%, suggesting considerable local variability in expertise. Typical ultrasound appearances are of a thickened loop of bowel with a target-like appearance. The same review found a wide range of sensitivities for CT varying from 65% to 97% with a specificity of 77–100%. The typical findings on CT are pericolonic fat stranding, bowel wall thickening and diverticular. Additional findings may include abscess, free fluid, free air, an inflamed diverticulum or the arrowhead sign in which contrast material shows an arrowhead configuration at the ostia of an inflamed diverticulum (Figure 3 shows an inflamed sigmoid diverticular segment with associated abscess). Studies comparing the two modalities are limited and the review concluded that it was difficult to draw firm conclusions, especially as the quality of CT has improved so much recently. The recent ACPGBI position statement concluded that the choice between the two modalities should be made on local expertise. The recent American College of Radiology Guidelines suggested CT in the first instance as US was limited by operator expertise. Ultrasound, however, may have a role in premenopausal women and the young to reduce radiation exposure. Barium enema sensitivity varies from 29% to 93% with specificity of 50–100%, but its inability to visualise extra-luminal complications means that it is no longer used acutely.
(Enlarge Image)
Figure 2.
Investigation and treatment algorithm for patients presenting with suspected acute diverticulitis based on current guidelines.
(Enlarge Image)
Figure 3.
CT scan of acute sigmoid diverticulitis with associated abscess formation (white arrow), which required surgical resection.
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