Simple appendicitis cannot be distinguished from complicated appendicitis by clinical examination and laboratory findings say Finnish investigators. They looked at data from their randomized prospective trial of antibiotics vs. surgery for treatment of appendicitis and concluded that only CT scans could reliably differentiate the two entities.
The study involved adult patients from 18 to 60 years old; 368 of whom had uncomplicated acute appendicitis and 337 had complicated appendicitis—appendicolith, perforation, or abscess.
Duration of symptoms, C-reactive protein, white blood cell count, and temperature were significantly different between simple and complicated appendicitis patients. However substantial overlap of values meant they were not helpful in predicting the presence of complicated appendicitis.
Receiver operating curves for C-reactive protein and temperature areas under the curve do no exceed 0.77. Combining these parameters did not improve accuracy.
The paper concluded that CT scanning is essential in diagnosing acute appendicitis and identifying simple and complicated cases.
A companion study by many of the same authors looked at 1321 patients who presented with clinical and laboratory findings of possible appendicitis. Since their protocol called for confirmation of the diagnosis, all patients underwent CT scans, and 351 (27%) did not have appendicitis.
Just over half of that cohort had no abnormal findings, but another cause of their acute abdominal pain was found in 160 (46%) of patients including 45 with acute diverticulitis, 39 with gynecologic problems, and 76 with “other miscellaneous diagnoses.”
As in the other study, white blood cell count, C-reactive protein, temperature, and duration of symptoms were unable to discriminate patients with appendicitis from those having CT scans showing other diagnoses or normal findings.
Both Finnish papers do not mention the use of ultrasound for diagnosing appendicitis. If ultrasound is available and accurate in your hospital, use it, but we are not aware any research validating ultrasound as a method of distinguishing simple from complicated appendicitis.
In the discussion section of the paper, the authors cited a New England Journal of Medicine study showing that low-dose CT scanning delivered less than one-third the dose of standard CT scan while maintaining similar sensitivity and specificity.
But the dangers of radiation from standard-dose CT may be overestimated.
The cancers attributable to CT are projections based on the linear-no-threshold (LNT) hypothesis. LNT assumes that the body reacts linearly to radiation at all doses; meaning there’s no safe dose of radiation. Attributable cancers are an assumption based on an assumption–a quadratic assumption–the mother of all assumptions.
We know the rate of excess cancers in Hiroshima and Nagasaki atomic bomb survivors exposed to 1000 millisivert (msv) of radiation. We assume that the attributable risk of cancer from abdominal CT with a dose of 10 msv based on LNT is 1/100th the risk from 1000 msv. This assumption is unscientific because biological systems are non-linear. LNT ignores basic radiobiology–DNA repair.
Toxicologists have a maxim: “dose is poison.” 100 % oxygen causes blindness in neonates. Excessive water intake can cause cerebral edema. Would it not be absurd to claim there’s no safe dose of oxygen and water?
Radiation is everywhere. The annual background radiation is 3 msv (we won’t tell you that it is 1.5 msv higher in Colorado, because we’ll spoil your skiing vacation). In scenic Kerala, India, a popular tourist destination, annual radiation is 70 msv. Keralites receive the equivalent of 7 CT abdomens every year, and 700 chest x-rays a year or two chest x-rays a day for their entire lives. If LNT were true there should be 300,000 excess cancers in Kerala annually. The Indian government should evacuate Kerala stat. However, researchers have found no increase in cancer in coastal Kerala. I’ve (SJ) been to Kerala. I can attest people aren’t glowing and don’t have three eyes.
Ironically, the LNT was put forward because physicists thought models, other than linear models, would be too difficult to understand. Linear thinking is the easiest thinking. Work hard and you’ll do well; work harder and you’ll do better. It is a convenient, but wrong, heuristic about our non-linear world.
This does not mean we should eat radiation for breakfast. There is compelling evidence of carcinogenesis at doses greater than 100 msv. We support the judicious use of CT scans, but clinical acumen is insufficient if you are going to use antibiotics to treat simple appendicitis.
The “no safe dose of radiation” is a sensible precautionary principle–better safe than sorry. However, through sleight of hand, it is now asserted as fact. This is irresponsible.
Prudence requires we neither irradiate people frivolously nor scare people frivolously.
*Dr. Jha (@RogueRad) is an Assistant Professor of Radiology at the Hospital of the University of Pennsylvania