ACR Appropriateness Criteria®

Clinical Condition: Right Lower Quadrant Pain

Variant 1: Fever, leukocytosis, and classic presentation clinically for appendicitis in adults.

Note: Abbreviations used in the tables are listed at the end of the "Major Recommendations" field.

Variant 2: Fever, leukocytosis; possible appendicitis, atypical presentation, adults and adolescents.

Note: Abbreviations used in the tables are listed at the end of the "Major Recommendations" field.

Variant 3: Fever, leukocytosis, pregnant woman.

Note: Abbreviations used in the tables are listed at the end of the "Major Recommendations" field.

Variant 4: Fever, leukocytosis, possible appendicitis, atypical presentation in children (less than 14 years of age).

Note: Abbreviations used in the tables are listed at the end of the "Major Recommendations" field.

Summary of Literature Review

Few comparative imaging studies evaluating right lower quadrant pain are available. Most imaging reports center on disease processes, such as appendicitis. Because appendicitis is the most common cause of right lower quadrant pain, the focus of this narrative is on appendicitis and the accuracy of imaging procedures in diagnosing appendicitis, although consideration of other diseases is, of course, included.

Acute appendicitis is the most common acute abdominal disorder that requires surgery. In most patients with acute appendicitis, imaging may not be necessary, because the clinical presentation is sufficiently diagnostic to allow surgery. To date, however, no prediction rules for identifying subjects with appendicitis have been validated. In the published studies for imaging in appendicitis, the selection criteria for imaging are not often stated, but in most investigations, subjects with definitive clinical exam findings of appendicitis undergo operation without imaging. In the reported imaging studies, an average of 45% to 50% of imaged subjects had appendicitis, and 36% had nonspecific abdominal pain. Data on the overall effect of imaging on surgical treatment of appendicitis and patient outcome remain contradictory.

Radiographic diagnosis is of limited value for diagnosing acute appendicitis, except in occasional circumstances when an appendicolith or other ancillary findings are identified. Although barium enema has been used historically to diagnose appendicitis, it depends on the negative finding of nonvisualization of the appendix and may be quite uncomfortable in patients with acute appendicitis. Nonetheless, barium small-bowel follow-through or barium enema may be useful for other causes of right lower quadrant pain, including suspected small bowel obstruction, infectious ileitis, and inflammatory bowel disease. Finally, use of magnetic resonance imaging (MRI) for appendicitis has been reported in a few small case series, including in pregnant women.

Computed tomography (CT) is the most accurate study for evaluating patients without a clear clinical diagnosis of acute appendicitis. In a meta-analysis of prospective studies of the accuracy of CT and ultrasound (US) in adolescents and adults, CT demonstrated superior sensitivity (0.94, 95% confidence interval [CI]: 0.91 to 0.95) and specificity (0.95, 95% CI: 0.93 to 0.96) versus US (sensitivity 0.86, 95% CI: 0.83 to 0.88; specificity 0.81, 95% CI: 0.78 to 0.84). This analysis was based on studies of CT and US identified through December 2004, and included four studies that directly compared both modalities. The results of investigations of CT showed consistent results across all studies and institutions, while US investigations demonstrated heterogeneity, suggesting greater dependence on operator skill.

Another controversy is whether or not to use intravenous contrast in the CT evaluation of appendicitis. High accuracy has been reported for both techniques, and direct comparisons are lacking. However, the majority of the available evidence is on CT with intravenous contrast. Institutional experience may be the best determinant of appropriateness of intravenous contrast. More recently, emergency physicians and surgeons have suggested eliminating oral contrast from protocols for evaluating patients with suspected appendicitis in order to expedite evaluation and have a better preparation for surgery. There is as yet no proof that this protocol will have the same accuracy as those with oral contrast. A compromise position might be to use rectal contrast to opacify the bowel surrounding the appendix, particularly in thin patients. Both CT and US may be effective in detecting causes of pain unrelated to appendicitis. CT has been reported to show a non-appendicitis cause of abdominal pain in 20% of subjects, versus 15% for US. The range of diseases studied includes inflammatory bowel disease, infectious bowel disease, small bowel obstruction, acute gynecological conditions, and others.

CT appears superior to sonography in evaluating patients with periappendiceal abscess, especially when the abscesses become large. CT can be used to choose among different therapeutic options, including antibiotic treatment (with small abscesses), percutaneous drainage (with one to three well-defined medium-sized abscesses), and surgery (with extensive abnormality not amenable to percutaneous drainage).

CT and US have been less well evaluated in children than in adults. Many large prospective studies include subjects of all ages, despite the potential differences in imaging accuracy between children and adults due to smaller body size and less body fat in children. This makes it difficult to determine the accuracy of imaging in different subgroups. Further, the increased radiosensitivity of children makes the use of ionizing radiation of more concern for them. A systematic literature review through July 2004 revealed eight prospective evaluations of US for appendicitis in children. The pooled sensitivity of graded compression US was 91% (95% CI: 89% to 93%), and the specificity was 97% (95% CI: 95% to 99%). Only a single prospective study of CT in children was identified, reporting a sensitivity of 95%, and specificity of 98%. There is also a small literature on the use of US as an initial imaging study, followed by CT for equivocal cases. Such combined protocols demonstrate a sensitivity of 95% (95% CI: 83% to 100%), and specificity of 93% (95% CI: 87% to 97%). These results suggest that although CT is more accurate, US may also be appropriate in experienced hands, particularly if equivocal results are followed up by CT.

Nuclear medicine imaging with WBC scans has also been reported for evaluating right lower quadrant pain.

Evaluation of the accuracy of imaging in pregnant women has received little attention in the literature. In general, ionizing radiation from CT should be avoided during pregnancy, and US is clearly a safer imaging option. In the appropriate clinical setting, MRI can be accurate in excluding appendicitis where the US exam does not visualize a normal appendix.

Anticipated Exceptions

The following are available:

The National Guideline Clearinghouse™ (NGC) does not develop, produce, approve, or endorse the guidelines represented on this site.

All guidelines summarized by NGC and hosted on our site are produced under the auspices of medical specialty societies, relevant professional associations, public or private organizations, other government agencies, health care organizations or plans, and similar entities.