Bumping up appendicitis diagnostic accuracy

Dec 28 2012

By Eleanor McDermid, Senior medwireNews Reporter

It is well worth emergency doctors asking patients with abdominal pain how they were affected by driving over speed bumps on their way to hospital, research suggests.

"It may sound odd, but asking patients whether their pain worsened going over speed bumps on their way in to hospital could help doctors in a diagnosis," said lead researcher Helen Ashdown (University of Oxford, UK) in a press release.

"It turns out to be as good as many other ways of assessing people with suspected appendicitis."

The sensitivity of being "speed-bump positive" was 97%, making it more sensitive for appendicitis than migratory pain (65%), nausea or vomiting (79%), or rebound tenderness (71%) in this group of patients.

The study, which appears in the Christmas edition of the BMJ, included 101 patients with symptoms suggestive of appendicitis. Of the 64 patients who recalled travelling over speed bumps en route to hospital, 34 had histologically confirmed appendicitis, 33 of whom were speed-bump positive.

Assuming that all patients who did not recall travelling over speed bumps were speed-bump negative reduced the sensitivity to 77%, which still compared favorably to other means of assessment.

The specificity was low, at just 30%, making speed-bump positivity a poor "rule-in" test for appendicitis. Including patients with no recollection of speed bumps as speed-bump negative improved the specificity to 61%.

However, the high sensitivity of the test means that being speed-bump negative strongly rules out the possibility of appendicitis, say Ashdown et al.

"Moreover, some patients who were 'speed bump positive' but did not have appendicitis had other important abdominal diagnoses, such as a ruptured ovarian cyst, diverticulitis, or pelvic inflammatory disease," they add.

A total of 54 patients were speed-bump positive. Besides the 33 with confirmed appendicitis, a further seven had important abdominal diagnoses. In a post-hoc analysis, the sensitivity of speed-bump positivity for important abdominal diagnoses, including appendicitis, was 98%.

"We hypothesise that the worsening of pain when travelling over speed bumps in appendicitis may occur because the movement involved irritates the peritoneum in a similar way to that produced by testing for rebound tenderness on examination," say the researchers.

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