Don’t Overlook Ultrasound in Appendicitis Workup


Yahoo! presented an article discussing five common ailments misdiagnosed by physicians.  I will leave the discussion of the first four (rhinitis, iliotibial band friction syndrome, migraines and asthma) to other experts in those fields.  My eyebrows became raised upon reading the fifth – appendicitis.

The article correctly notes that appendicitis can be a difficult diagnosis, and that around 16% of appendectomies are done on those who do not have appendicitis.  This percentage is consistent with many past studies.  The article then suggests that a CT scan should be done, especially if the white cell count is over 10,000.  Disregarding the minor factual error (CT scans are not done for the “stomach”, but more precisely, the abdomen and pelvis), the article ignores the role of ultrasound.

We know that CT scans are not harmless tests.   The radiation involved in a CT scan is significant, especially in younger patients.  Although the question cannot be considered fully settled, there is mounting evidence that CT scans increase the risk of future cancers.  As in all situations in medicine, testing decisions have to be weighed in terms of the risks and benefits of each option.

Although not as sensitive or specific as CT scanning, ultrasound does not use radiation.  In light of the long-term effects of CT scanning, this makes ultrasound an attractive first test.   With a history and exam favorable for appendicitis, a positive or near-positive ultrasound is usually enough to make the decision to operate, especially in the setting of an elevated white count.  Adding a CT scan will seldom change this conclusion, but it adds radiation risk and system costs.

In cases where the ultrasound is inconclusive or suggests other pathology, CT may be an appropriate follow-up exam.

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3 responses to “Don’t Overlook Ultrasound in Appendicitis Workup”

  1. Setu says :

    A “not-a-doc” perspective: CT Scans may not be medically necessary in diagnosing various conditions, but I presume that providers will prefer the amount of reimbursement of CTs over that of U/S…they need to pay for those machine somehow.

  2. seattleskindoc says :

    TPane- agree with your comments on the overuse of CT and underreliance on U/S as aid to diagnose appendicitis. The other element of this issue is the ‘negative laparotomy’ …as you know, yet the public fails to recognize- A negative laparotomy (false positive test) for appendicitis is not necessarily a failure of diagnosis- its merely a reflection of trying to minimize the number of ‘false negative’ assessments that surgeons make- appendicitis is deadly when not recognized and treated. I still have my copy of Cope’s Early Diagnosis of the Acute Abdomen. A classic.

    • Thomas Pane says :

      Cope’s is a classic! Still have mine too.

      The public has a hard time understanding the importance of a negative laparotomy, but that is preferable to a missed appendicitis.

      I was surprised the author did not mention ultrasound. If it comes up positive or suggestive, and if other signs are pointing the same way, you can omit the CT. Especially in children, where its even more important to use the minimum amount of radiation to aid the diagnosis.

      Tom

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