Appendicitis in children and radiation exposure from CT scans

Recently, medical writer and pediatrician Perri Klass wrote in the New York Times about evolving issues regarding the diagnosis of appendicitis in children, which are also applicable to adults. There is well-documented concern regarding the excessive radiation exposure associated with CT scans.

For example, a recent paper reported that a single abdominal CT scan with contrast delivers a radiation dose equal to undergoing more than 200 regular chest x-rays. The implications of this large dose of radiation are that an increase in cancer rates may arise in the future, especially if the CT scan is performed in a child.

The problem is how does one curtail the use of CT scans for the diagnosis of appendicitis when the test has become extremely accurate? Although Klass states that a normal appendix can be expected in 10-20% of appendectomies, those numbers are no longer valid. Even in a non-teaching community hospital, the rate of removal of a normal appendix during emergency surgery for the diagnosis of appendicitis should be well below 10%. She also repeats a commonly held misconception that a high rate of removal of normal appendices results in a lower rate of perforated appendicitis, which is not true. Some authors even believe that perforated appendicitis is a different disease than simple acute appendicitis.

I do not see the rate of CT scans for appendicitis decreasing because of three major factors.

1. Patients [or their parents] have come to expect accuracy in diagnosis. On more than one occasion, I have had the experience of seeing a teenage boy with classical symptoms and signs of appendicitis where the emergency physician has called me and said he did not think a CT scan was necessary. I examined the child and agreed. After I explained everything to the mother, she said, “What about the CT scan?” It then becomes hard to go ahead without the scan because in the unlikely event the boy did not have appendicitis, the mother would have accused me of performing unnecessary surgery. In fact, of my last 80 appendectomies, I have operated without a CT scan only four times. My rate of removal of a normal appendix is 6%. This is in a non-teaching community hospital with out-sourced CT scan readings at night.

2. Klass mentions the use of ultrasound as a substitute for CT scan. Although ultrasound does not involve radiation and is accurate according to some studies, the reality is that it is not always readily available at night [when most people with abdominal pain show up] in many community hospitals. The test is useless when the appendix is not identified, a situation that occurs frequently outside of academia. And unlike CT scan, ultrasound is far less likely to reveal an alternative diagnosis when the appendix is normal.

3. In a non-teaching hospital where there are no residents, it is very difficult to have every patient with a suspicion of appendicitis seen by a surgeon. When the emergency physician calls and says she has a patient with a positive CT scan for appendicitis, the diagnosis is correct more than 95% of the time. They rarely call when the CT scan is negative. Some scans are equivocal and the surgeon does have to see the patient and make a clinical decision. Regarding patients with positive CT scans for appendicitis, it pains me to say this but the history and physical exam are probably no longer relevant. This is particularly true now that all patients with abdominal pain receive narcotics within a few minutes of arrival to most EDs. It takes cojones to not go ahead with surgery when the CT scan is read as positive for appendicitis. I have done it once [successfully] in the last 19 months. Of course, I look at all the CT scans myself to usually confirm or rarely question the reading.

It comes down to this. Do you want an accurate diagnosis for yourself or your child with the possible increased risk of cancer years later or would you accept a higher rate of normal appendix removal? I believe that the general public would opt for the former.

Skeptical Scalpel is a surgeon blogs at his self-titled site, Skeptical Scalpel.

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