AssessmentsAppendicitis: Clinical practice
USMLE® Step 1 style questions USMLE
USMLE® Step 2 style questions USMLE
A 25-year-old man comes to the emergency department because of excruciating abdominal pain. The abdominal pain is localized to the right lower quadrant. A day ago, the abdominal pain was located in the periumbilical region and was less severe. His temperature is 37°C (98.6°F), pulse is 95/min, respirations are 18/min, and blood pressure is 130/80 mm Hg. Abdominal examination shows tenderness with deep palpation. Laboratory studies show a leukocyte count of 15,000/mm3. Which of the following is the most sensitive finding for the patient's likely diagnosis?
Content Reviewers:Rishi Desai, MD, MPH
Contributors:Tanner Marshall, MS, Alex Aranda, Jake Ryan, Antonella Melani, MD, Robyn Hughes, MScBMC
Appendicitis is when the appendix gets inflamed, and it’s the most common surgical emergency of the abdomen.
Normally, the appendix can be found in a retrocecal location, as well as preileal, postileal, pelvic and subcecal.
Since the appendix is a hollow tube, the most common cause of inflammation is something getting stuck in or obstructing that tube.
That something could be a fecalith, a hardened lump of fecal matter, an undigested seed, or even intestinal parasites like pinworms.
Another cause of obstruction, especially in children and adolescents, is lymphoid follicle growth, also called lymphoid hyperplasia.
Lymphoid follicles in the appendix grow in size during adolescence, and they can sometimes obstruct the tube.
Early on acute appendicitis causes periumbilical abdominal pain, nausea, and vomiting.
Sometimes there can be other atypical symptoms like indigestion, flatulence, diarrhea, and malaise.
Within 24 to 48 hours, the appendix becomes more swollen and inflamed, and it begins to irritate the abdominal wall, causing the pain to get more severe and localized to the right lower quadrant, as well as causing a fever.
This classic migration of pain may not be seen in children under three years old.
Another sign of appendicitis is Rovsing’s sign, which is when palpation of the left lower quadrant causes pain in the right lower quadrant.
The obturator sign when the inflamed appendix lies in the pelvis and causes irritation of the obturator internus muscle.
Now if obstruction persists, the pressure in the appendix increases even more, and the appendiceal walls become weaker and weaker, up to the point where the appendix may rupture.
Perforation of the gastrointestinal tract allows bacteria to escape the appendix and get into the peritoneum.
An important and early sign of peritoneal irritation is abdominal guarding, which is when an individual tightens their abdominal muscles during palpation to try and avoid pain.
Blumberg's sign, also referred to as rebound tenderness, refers to palpation and quick release, with pain felt upon release of pressure - again a sign of peritoneal irritation.
Diagnosis of appendicitis can be supported by laboratory tests.
Typically in blood tests, the white blood cells count is elevated with a neutrophil predominance, and there’s an elevated CRP.
Blood tests may also show dehydration or fluid and electrolyte imbalances.
A urinalysis should be done to rule out genitourinary conditions as the cause of abdominal pain.
Irritation of the bladder or ureter by an inflamed appendix may result in mildly elevated urinary white blood cell count, while a significant elevation suggests there’s a urinary tract infection.
In addition, to rule out ectopic pregnancy, postmenarcheal pediatric cases should get a urine pregnancy test, and adult females should obtain a serum pregnancy test.
So individuals with classic findings may be taken for immediate surgery without imaging studies, while individuals with atypical presentation may need further testing to rule out conditions like bowel obstruction, ovarian or testicular torsion, and kidney stones.
Plain abdominal radiography is not useful in making the diagnosis of appendicitis and should not be routinely obtained.
Ultrasound is the preferred first choice, while CT scan is done as follow-up if the ultrasound is inconclusive.
MRI is recommended over CT scan in pregnant women and children who can cooperate, to minimize radiation exposure, but it often can’t be done emergently.
On ultrasound, there’s usually an enlarged appendix with a diameter of more than 6 millimeters, as well as tenderness over the appendix with compression of the ultrasound probe.