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Tips for Diagnosing Appendicitis
By Jeffrey E. Keller MD
Published: 04/25/2016

One of the last remnants of my previous life as an Emergency Physician is that I am still to this day the Medical Director of the local fire department and paramedics. I also do the fire fighters’ yearly wellness physical exams.

(As an aside, my wife helps me by drawing blood, doing EKGs, getting patients’ prepped, etc. She tells everyone who will listen: “I have the best job in the world. I tell fire fighters to get naked—and they do! Every woman wants my job.”)

Anyway, recently, a paramedic came to me with this nagging abdominal pain that he had had for over six months. It was never so bad as to make him quit working, but it never went away either. After I looked him over, I thought he might have appendicitis—but for six months? I sent him for a CT and sure enough he went straight to surgery. It turns out that he had actually ruptured his appendix six months ago and he had been walking around ever since with a walled-off intra-abdominal abscess.

This is an extreme example of just how weird and tricky appendicitis can be to diagnose. Some cases of appendicitis are so easy to diagnosis that the janitor could do it: “That guy doesn’t look so good.” Other cases are very hard to pick up, like Rob the paramedic. The main difference between the two is where the appendix sits anatomically in the abdomen—but more about that in a bit.

Appendicitis—The Pus Balloon

The appendix is a hollow little bit of gut attached to the cecum of the large intestine near to where the small intestine attaches. If a bit of hard stool gets caught in the appendix so that it can no longer drain into the cecum, it can get infected and begin to swell with pus like a balloon. That is appendicitis.

Like any infection, of course, appendicitis hurts. However, the visceral pain receptors attached to the gut are different than the pain receptors located in the abdominal wall. The initial visceral discomfort of appendicitis is a vague uneasy sensation. It is hard for patients to say exactly where it is; they tend to point to their belly button or make a sweeping gesture over their belly.

Once the appendix swells up enough to involve the innermost layer of the abdominal wall (the peritoneum), the pain pattern changes. Peritoneal pain is just like that you would feel on your skin. It hurts sharply and “Right there.” Since the appendix tends to be located in the right lower quadrant, patients are usually pointing to their low right belly at this point. This is localized peritonitis. From the time that appendicitis begins until it progresses to localized peritonitis is usually 8-12 hours.

The peritoneum is stretched like a drum head between the ribs and the pelvis. When it is inflamed, anything that makes it vibrate (like a drum head) causes severe pain. You can cause this by pushing in and suddenly releasing—the classic “rebound” effect, but you can also see peritonitis by the way the patient walks. Patients with peritonitis walk very gingerly because a hard step makes their peritoneum vibrate and hurts.

If the appendix ruptures, patients sometimes feel better for a short time because the pressure was released. However, the pus that was spewed everywhere causes diffuse peritonitis and patients get really, really sick.

Very rarely, the appendix just leaks a little bit and the body is able to contain it by walling it off with scar tissue, as in my friend Rob the paramedic.

Why is it so hard to diagnose appendicitis?

Whether appendicitis is easy to diagnose or not depends on how quickly the peritoneum is involved. Early appendicitis that causes only visceral pain is very hard to diagnose, sometimes impossible. Once the peritoneum is involved, the diagnosis is easier to make. And how quickly the peritoneum is involved depends on where the appendix sits anatomically in the abdominal cavity. If the appendix happens to be located right by the abdominal wall, the peritoneum will hurt soon and a lot and that patient will quickly be correctly diagnosed. If the appendix happens to be located in the exact middle of the abdominal cavity, far away from the abdominal wall, it can swell mightily and may even rupture before the peritoneum is ever involved. That case of appendicitis might be really hard to diagnose.

From a clinical perspective, another reason that appendicitis is hard to diagnose is that there is no one symptom or physical finding that always occurs with appendicitis. For example:
  • Most patients with appendicitis initially have a vague abdominal discomfort that later localizes to the right lower quadrant—but not everybody.
  • Most patients vomit—but not everyone.
  • Most patients have a low grade fever, say 100.5—but not everybody.
  • Most patients do NOT have diarrhea—but not everybody.
  • Most patients will not eat and will not be hungry (medical term = anorexia)—but not everybody.
  • Most patients will have an elevated white blood cell count—but not everybody.
  • Most patients will have ketones in their urine (from dehydration because they have not been drinking)—but not everybody.
  • On exam, most patients will have pain in the right lower quadrant with maybe rebound pain—but not everybody.
I could go on but you get the drift.

So no one of these findings is enough to either make the diagnosis or exclude it. However, you can use this list as a whole to help you. I call this comparing the patient to the clinical syndrome. How closely does the patient match the whole list, knowing that almost nobody has every finding. For example, compare these two patients:
  1. Inmate “A” began having belly pain 14 hours ago. It now seems to be settled the low right side. It hurts to take a hard step. He did not eat breakfast or lunch. He has not vomited. Vital signs are normal except for a temperature of 100.1F. WBC count is normal at 7.5.
  2. Inmate “B” comes to clinic clutching his right lower quadrant: “It hurts so bad.” The pain started 3 hours ago. He ate breakfast 2 hours ago “but I threw it up.” He also states that he had 2 episodes of diarrhea. Vital signs are normal. The patient complains of pain everywhere on his abdomen.
I would strongly suspect that inmate A has appendicitis despite his normal WBC. I would send him to the ER. On the other hand, I doubt that inmate B has appendicitis or, at least, it is too early in the course to be sure. That brings us to the definitive test (if there is such a thing) for appendicitis.

My Favorite Test: The 8 Hour Test

Of all of the signs and symptom that may be associated with appendicitis that are listed above, the ones that I personally give the most weight to are the time course (onset of pain to presentation being around 8-12 hours), anorexia and the abdominal exam. The White Blood Cell count is NOT on this list. I have found it to be nearly useless.

However, the best test for questionable cases of appendicitis is what I call “The 8 Hour Test.” That is, you reassess the patient in 8 hours. The basis for the 8 Hour Test is that appendicitis almost always gets worse with time. In 8 hours, the patient will not be the same. He will be either improved or worse. If he really does have appendicitis but the time course is too early to make the diagnosis, it likely will be clinically apparent in 8 hours. If it still isn’t, you can order another 8 Hour Test.

The 8 Hour Test should be considered to be a real, honest-to-goodness-test, by you, your patient and the nurses. It will give you far more useful information than, say, a CBC. And if you think 8 hours is too long to wait, you can do a 4 Hour Test or even a 2 Hour Test instead.

What about a CT Scan?

There is no question that the CT scan can be a very useful test in questionable cases of appendicitis, especially in women. Since the female reproductive organs lie in close proximity to the appendix, and since ovarian cysts, say, can cause pain that closely mimics that of appendicitis, it is even harder to diagnose appendicitis in women than in men. The CT scanner often can be very useful. However, the CT scanner has limitations that you must keep in mind.

  1. The CT scanner is not perfect. CT scans sometime suggest appendicitis when no appendicitis is found at surgery. Even more often, CT scans sometimes miss true appendicitis.
  2. No contrast is needed for an abdominal CT looking for appendicitis, but many radiology departments insist on both IV and oral contrast anyway. The time and hassle this adds to the procedure often make it just worth it.
  3. Whenever you transport an inmate outside of the secure facility, there is a security risk that must be factored in. Is the CT really worth the risk?
I (and others) have found that the 8 Hour Test is more than enough in most questionable cases. If I am still not sure and think that a CT scan may help, I will usually send the patient to the ER for a second opinion, which may or may not include a CT.

Have you had an interesting or unusual case of appendicitis at your facility? Please share!


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