Abdominal pain is the most common manifestation of gastrointestinal involvement in patients who have systemic lupus erythematosus (SLE). The most common cause of SLE is intraabdominal vasculitis, a dangerous manifestation that results in ischemia and intestinal infarction. Diagnosing acute primary mesenteric ischemia is challenging. Prompt, intensive radiographic evaluation of patients with SLE and acute abdominal pain is essential to identify the potential causes of the pain. Plain radiographs of the abdomen or contrast material–enhanced radiographs of the bowel are often normal or nonspecific. Byun and associates conducted a retrospective review of computed tomographic (CT) scans in a series of patients with SLE and acute abdominal pain to identify any distinguishing features.
Thirty-nine CT scans from 33 patients who met the diagnostic criteria were reviewed by two experienced radiologists, and diagnoses were reached by consensus. A CT examination was performed within two days of the onset of pain. All patients reported repeated episodes of abdominal pain and were taking low-dose oral prednisone at the time of presentation. A CT diagnosis of ischemic bowel disease was made if the patient had at least three of the following signs: bowel wall thickening, target sign, dilation of intestinal segments, engorgement of mesenteric vessels or increased attenuation of mesenteric fat.
Thirty-one CT scans showed one or more of the defined characteristics of ischemic bowel disease. Of these, 29 had circumferential, symmetric bowel wall thickening, primarily at the jejunum and ileum. Most of these scans (90 percent) also demonstrated the target sign. In 24 of the scans, the thickening appeared to be multisegmented, was of variable length and did not appear to be confined to a single vascular territory. Engorgement of the mesenteric vessels and increased attenuation of mesenteric fat adjacent to the involved bowel loops were evident in all scans. Ascites was also noted in 27 scans. In patients whose CT findings showed no apparent ischemic bowel disease, other conditions, such as splenic infarction, thrombosis of the inferior vena cava, pancreatic cancer, liver abscess and lupus nephritis were discovered. Six patients with CT findings of ischemic bowel disease had an acute recurrence of abdominal pain after recovery from the initial episode. Repeat CT scans were obtained one to 32 months after the initial examination. In five patients, CT findings of ischemic bowel were noted again with partial regression and little change or progression when compared with the initial scans.
The authors conclude that a CT examination was useful for identifying the primary causes of acute abdominal pain in patients with SLE. These findings were also useful in planning treatment and in monitoring for infarction and perforation. Although ischemic bowel disease was evident on the CT scans of most of the patients, variable findings were seen in eight patients without CT findings of ischemia. Although CT proved to be more sensitive than specific, it may provide a more accurate way to diagnose acute mesenteric ischemia and reduce life-threatening complications.