Priscilla Marsicovetere is Assistant Professor of Medical Education and Surgery, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, and Program Director for the Franklin Pierce University, PA Program, Lebanon, New Hampshire. She practices with Emergency Services of New England, Springfield Hospital, Springfield, Vermont.
The author has no financial relationships to disclose.
Because leukocytosis is present in approximately one-half of patients with diverticulitis, a complete blood count (CBC) should be obtained; that recommendation notwithstanding, approximately one-half of patients with diverticulitis have a normal white blood cell count.29,30 A urine test of human chorionic gonadotropin should be ordered to exclude pregnancy in all premenopausal and perimenopausal women, particularly if antibiotics, imaging, or surgery are being considered.31 Urinalysis can assess for urinary tract infection.
Multiple studies have demonstrated the utility of C-reactive protein (CRP) in the workup of acute diverticulitis. In general, patients with a complicated episode will present with a significantly higher CRP level than that of uncomplicated disease.32 Kechagias et alfound that the CRP level at initial evaluation may be helpful in predicting the clinical severity of the attack. A CRP level > 170 mg/L has been found to have a greater probability of severe disease, warranting CT and referral for hospitalization.33 A low CRP level was more likely to herald a mild course of disease that is amenable to outpatient antibiotic management or supportive care. This finding is consistent with previous reports of the association between CRP levels of 90 to 200 mg/L and the severity of diverticulitis.32,34
Imaging
Abdominopelvic CT with intravenous (IV) contrast. This imaging study is the gold standard diagnostic tool for diverticulitis, with sensitivity as high as 97%.3 CT can distinguish diverticulitis from other conditions, such as irritable bowel syndrome (based on a history of symptoms and the absence of CT findings), gastroenteritis, and gynecologic disease. It can also distinguish between uncomplicated and complicated diverticulitis and therefore guide therapeutic interventions, such as percutaneous drainage of an intra-abdominal abscess. CT findings associated with uncomplicated diverticulitis include colonic wall thickening and pericolonic fluid and inflammatory changes, such as fat stranding. CT findings associated with complicated disease include abscess (paracolonic or pelvic), peritonitis (purulent or feculent), phlegmon, perforation, fistula, and obstruction.1,3
Ultrasonography(US) can also be used in the assessment of diverticulitis, although it has lower sensitivity (approximately 61% to 84%) than CT and is inferior to CT for showing the extent of large abscesses or free air.3,18,30 A typical US finding in acute diverticulitis is a thickened loop of bowel with a target-like appearance.17 Findings are highly operator-dependent, however, and accuracy is diminished in obese patients. US may be a good option for pregnant women to avoid ionizing radiation.
Magnetic resonance imaging (MRI) is another option for imaging in diverticulitis but is not routinely recommended. It provides excellent soft-tissue detail and does not deliver ionizing radiation, but it is not as sensitive as CT for identifying free air.18,31 Furthermore, MRI requires prolonged examination time, which may not be tolerated by acutely ill patients, and is not an option for patients with certain types of surgical clips, metallic fragments, or a cardiac pacemaker.
