Grand Rounds: A Review of Appendicitis

Grand Rounds is a new monthly blog series developed by EMS World and FlightBridgeED that will feature top EMS medical directors exploring the intricacies of critical care in EMS practice. In this installment FlightBridgeED Chief Medical Director Jeffrey Jarvis, MD, PM, reviews appendicitis.

Appendicitis has been around as long as we’ve had appendices, but we haven’t always known about them. If we hop in our Wayback Machine, we find Leonardo da Vinci drew it first: He labeled it orecchiette, which means little ear. I guess he felt it looked like a little ear hanging off the face of the cecum.

Once we figured out what appendicitis was, we had to figure out what to do about it. Initially it was managed medically, which meant the pinnacle of “modern” medicine at the time: leeches, herbs, and spices. And then we figured out surgery. The first appendectomy happened almost by accident: In 1735 a surgeon was operating on the inguinal hernia of an 11-year-old boy (without anesthesia, I might add). Since they didn’t have laparoscopic surgery back in the day, they did a big open laparotomy. They found a nasty, gangrenous appendix just hanging out, causing trouble. Out it came, and, other than possible PTSD from the anesthesia-free surgery, the patient did well.

Surgery became the treatment of choice for appendicitis after the successful appendectomy of King Edward VII, which occurred several days before his coronation. And another interesting factoid: The only fatality of the Lewis and Clark expedition is reported to have been from appendicitis.

Anatomy

The appendix is a skinny, blind (meaning dead-end) pouch (Figure 1). It comes off the cecum just posterior and inferior to where it joins the ileum. This area is the junction between the small and large bowels. The cecum is a larger dead-end structure. It is about 7 by 7 cm and is the start of the ascending colon. The appendix is also called the vermiform appendix. Vermiform means wormlike, and it sort of looks like a worm. To put it into perspective, the cecum turns into the ascending, then transverse, then descending colon and finally rectum.

The appendix is normally narrow and easily collapses with any pressure. It has a total volume of less than 0.3 mL when not inflamed. It also has a very variable position, meaning it can be found in different places off the cecum in different people.

In most people the appendix lies under McBurney’s point. Figure 2 shows an imaginary line running between the anterior superior iliac spine and the umbilicus.

McBurney’s point is one-third of the way toward the umbilicus. This area is supposed to be the point of maximal tenderness in a patient with classic appendicitis. We have all seen patients with appendicitis who did not hurt exactly over this point. That is because the appendix can live in many different positions. Because its location is variable, where a patient hurts can also be variable.

You may have wondered what the appendix does. Well, we’re not all that sure. It’s not that important, since many of you cope quite well without one. Perhaps it is a vestigial remnant of an organ that once did something important. The best function we can figure out these days is that it seems to serve as a reservoir for good bacteria. These good bacteria colonize the colon and help inoculate it from pathogens.

The appendix gets its nerve innervation through the sympathetic trunk around T10. The sympathetic trunk also innervates the abdominal wall around the umbilicus, but the quantity of sensory nerves in this area is pretty low. This leads to vagueness and difficulty in pinpointing the exact point of pain. The classic description of pain in patients with appendicitis begins at the umbilicus because of this innervation. There is also innervation throughout the peritoneum. This is a bit better localized. When the appendix becomes irritated, it irritates surrounding structures, and the pain can then migrate to the right lower quadrant (or wherever the appendix happens to lie in that particular patient).

Pathophysiology

Because the appendix is a narrow dead-end tube, it is at risk for occlusion. This occlusion is the classic pathophysiology of appendicitis. Obstruction may be from a tumor or foreign body (there was one case caused by a tongue stud someone managed to swallow) but is most commonly from an appendicolith, a calcium stone. Like all the bowel, the lining of the appendix is always making secretions. When not obstructed these pass out of the appendix and into the cecum without a problem. However, when there is an obstruction, the secretions build up and eventually exert pressure on the wall of the appendix, causing stretching that triggers pain receptors.

Additionally, the increased pressure on the wall of the appendix can exceed the arterial pressure of the blood supply to the appendix, leading to ischemia. Ischemia is also painful. Finally, with prolonged ischemia comes gangrene and perforation, then the formation of an abscess and adhesions.

The natural history of appendicitis is that this process occurs and often spontaneously resolves without any issues. Treatment is now starting to include just antibiotics and observation without surgery. If you think about it, this is pretty much what diverticulitis is, and although it used to be a surgical disease, diverticulitis is now almost exclusively treated with antibiotics. Surgery is reserved for complicated cases that do not respond to antibiotics.

Presentation

Let’s discuss the textbook presentation of appendicitis, understanding that patients do not always present in classic fashion.

The initial symptom is a vague abdominal discomfort poorly localized around the umbilicus that then migrates down to the RLQ. The pain is associated with nausea, vomiting, and fever. The pain is typically acute and has been around less than 48 hours.

There are several classic physical exam findings with appendicitis, and most of them have names.

• We’ve already talked about McBurney’s point. McBurney’s sign is when the point of maximal tenderness is over McBurney’s point.
• Rovsing’s sign is considered positive when there is pain that is referred to the RLQ when palpating the LLQ.
• The obturator sign is positive with RLQ pain increases when the hip is flexed with slight external rotation.
• The psoas sign is positive when RLQ pain increases when the hip is extended.
• Rebound tenderness, a sharp increase in pain after a sudden release of gradually applied palpation, is a late sign in appendicitis. It is more a sign of peritonitis and can be seen in lots of conditions that cause it.
• Jolt attenuation is similar to rebound tenderness. It occurs when there is an increase in pain with tapping on the heels of the feet or having the patient jump up and down. It’s one of my favorite ways of ruling out appendicitis and meningitis in patients who have a low pretest probability of the disease being present.

Of these tests, the ones with the highest likelihood ratios (i.e., best at diagnosing the condition when present) are localized RLQ tenderness, migration of the pain from the umbilicus to the RLQ, and rigidity. As a reminder, tenderness is what you elicit with palpation; pain is what the patient experiences without your pokey fingers. The findings with the highest negative likelihood ratios (best at ruling the diagnosis out) are pain for more than 48 hours, prior similar episodes, no migration, and a negative jolt attenuation test.

Fever, which we would like to think needs to be present, is not all that good. It is only present in 15% of cases and only 40% of patients with perforation.

Because not all patients with appendicitis are crystal clear, we should always form a reasonable differential diagnosis for patients with abdominal pain. In this case we should also consider acute gastroenteritis, ascending diverticulitis, IBS, renal colic, gallstones, and typhlitis. In men we should add testicular torsion, and in women we need to consider ectopic pregnancy, ovarian torsion, PID, and ovarian cysts.

The primary complication of appendicitis is infection and abscess. Some type of infection occurs in 3% of cases, but they’re more common in the elderly and immunocompromised. Patients can develop small bowel obstruction, particularly after resolution or surgery, because of adhesions that give the small bowel a point to twist around. In pregnant patients premature labor occurs in up to 15%–40%. The overall mortality rate of uncomplicated appendicitis in the U.S. is under 0.1% but goes up to 3%–4% with comorbidities and perforation. The perforation rate is between 30%–40%, but it’s more common in the elderly and young children.

At the ED

So that we know what will happen to our appendicitis patients once they get to the ED, let’s go over the workup.

Labs will almost always be done and will seldom be particularly helpful. We expect to see a leukocytosis (elevation in white blood cells). It turns out that as long as we consider above 10,000 to be elevated, we see this in 80%—90% of patients. Unfortunately, it does not take much to get a WBC count above 10,000, so this is a low threshold and very nonspecific. Lots of people have appendicitis with normal WBC, so we cannot use this to rule it out.

Similarly, C-reactive protein is often thought to be useful but turns out to be pretty worthless in ruling appendicitis out. Even a urinalysis, which we’d like to think would be helpful to distinguish between appendicitis, UTI, and kidney stones, is not helpful. Unfortunately, appendicitis can irritate the ureter and cause some trace blood and white cells, so its value is low too.

The real way to diagnose appendicitis in the modern age is by imaging. It used to be that if a surgeon was not taking out a certain number of normal appendices, they were not taking enough people to the OR, and they were likely missing some cases of appendicitis. This is not the case anymore. Our imaging modalities have gotten so good that I cannot think of the last time (outside of setting up observation in young children) I saw a suspected appendicitis without confirmatory imaging. The two workhorse imaging modalities are ultrasound and CT.

Ultrasound has a sensitivity between 75%–95% and specificity between 85%–90%. It is best in skinny patients. The benefit is that it does not involve any radiation. The downsides are that it is very operator-dependent, does not work well in obese patients, and sometimes the appendix cannot be visualized.

The diagnostic findings on ultrasound are a large, noncompressible appendix (Figure 3). The ultrasound machine can measure both the diameter of the appendix and thickness of the wall.

The main benefit of ultrasound is that it is relatively cheap and involves no radiation exposure. If the appendix is visualized, it is diagnostic. The downside of ultrasound is that it does not give us useful information with poor images and does not do well in obese patients or after perforation. It is our go-to initial test in children and pregnant women in whom we want to avoid radiation.

CT imaging (Figure 4) is about as close to a gold standard for appendicitis as we have right now. It is excellent, although not perfect. It is possible, although unlikely, to miss a very early appendicitis on CT. The CT will show a dilated appendix with some stranding or inflammation in the surrounding tissues. The main benefit of CT is that it is fast and reliable. It works better when there is a bit of fat around the appendix and can give us helpful information about other potential pathology when the diagnosis is uncertain. The main downside to CT is radiation exposure and cost. These scans are often performed with IV contrast, which has some risk of contrast-induced nephropathy and allergic reaction.

Treatment

First and foremost help make the patient more comfortable. Give them IV fluids if they have been vomiting and look dehydrated, treat their nausea and pain. There is no good reason to withhold pain medication in patients with abdominal pain until a physician evaluation. While this used to be taught, it is now archaic and cruel. Plus, it never made sense: There is good evidence opioids did not increase the likelihood of a misdiagnosis. Plus, in the modern age where the diagnosis is with imaging, fentanyl does not impress the CT scanner at all.

After the diagnosis is made, patients will get antibiotics. In the U.S. most patients with uncomplicated appendicitis will then have a laparoscopic appendectomy. In Europe surgeons are sometimes opting for antibiotics and close observation. Outcomes look promising with this strategy, but it has not been thoroughly vetted yet. While we’d all prefer to avoid an unneeded surgery, it seems like many of the patients with antibiotics-only treatment had recurrent episodes and eventually had appendectomies.

For patients who’ve had a perforation and now have an intra-abdominal abscess, surgeons will frequently delay the surgery until interventional radiology drains the abscess and antibiotics have a chance to calm everything down.

Summary

The key points here are the physical exam, thinking about the possibility of appendicitis and keeping it on your differential, and treating the patient’s pain.

Jeffrey L. Jarvis, MD, MS, EMT-P, FACEP, FAEMS, is the chief medical director for FlightBridgeED, LLC. He also serves as EMS medical director for the Williamson County (Tex.) EMS system and Marble Falls Area EMS and an emergency physician at Baylor Scott & White Hospital in Round Rock, Tex. He is board-certified in emergency medicine and EMS. He began his career as a paramedic with Williamson County EMS in 1988 and continues to maintain his paramedic license.