Appendicitis

1. Clinicial hx and ddx in appendicitis:
--most commonly presents in the 2nd and 3rd decade, men>women
--incidence is highest young adults age 10-19
--"classic" constellation of symptoms includes: RLQ pain, anorexia, nausea/vomiting
--pain can "migrate" starting periumbilical then to RLQ (variable)
--location of appendix is actually quite variable, ranging from low in the R pelvis, to relatively high in the R-mid abdomen (obviously in patients like this with abnormal anatomy it can be even more variable)
--nonspecific signs: flatulence, indigestion, diarrhea, malaise
--fever and leukocytosis are variable and usually occur later in the course of illness
--ddx includes:meckel's or cecal diverticulitis, acute ileitis, Chron's disease, gynocologic processes (ruptured ovarian cyst, ovarian torsion, PID, etc.)

2. Diagnosis of appendicitis: PE
--classically, appendicitis has been a clinical diagnosis (ie. pts were diagnosed based on hx and PE alone, and the decision tree involved operative managment vs. careful observation); however, in the past decade or 2, we have moved to much more dependence on imaging studies in helping triage the patients who need to go to the OR.  This approach has been shown to be cost effective and decreases rates of nontherapeutic appendectomies
--TTP at McBurney's point, defined as a location 1.5 to 2 inches from the anterior superior iliac spine (ASIS) when a line is drawn from the ASIS to the umbilicus:  sens 50 to 94 %, spec 75 to 86 %
--Rovsing's sign: pain in the RLQ with palpation of the LLQ: sens 22 to 68%, spec 58-96%
--Psoas sign: right lower quadrant pain with right hip flexion, indicates a retrocecal appendix. Specificity 79-98%, but not sensitive.
--Obturator sign: when the examiner flexes the patient's right hip and knee followed by internal rotation of the right hip, this elicits right lower quadrant pain.  Sign of an inflammed pelvic appendix; again, Specific (98%), but not sensitive.
--if the patient has a ruptured appendix, the pain can still be localized to the RLQ if the appendix has walled off; if not, they may have diffuse abd tenderness (peritonitis)

3. Diagnosis of appendicitis: Imaging
--CT vs. US: decision is largely based on pt demographics, however most studies have found CT to have a higher specificity than US(>90%% w IV contrast vs. 71-98%) and much higher sensitvity (>90% vs. 35-98%)
--US is most useful in patients w a contraindication to radiation (ie. pregnant women and often avoided in children as their risk of cancer 2/2 radiation exposure seems to be much higher than adults)
--again, US is helpful if the appendix is well visualized, but does NOT rule it out
--CT non-con vs. w contrast: most studies state slightly lower sensitivity with a non-con CT (88-98%) than with IV contrast (91-98%).  In general, pts with more adipose tissue are better candidates for non-con CTs as their abdominal fat will provide some natural contrast with the bowel and other organs
--additional advantage to CT over US is that it may help elucidate other causes for abd pain (although RUQ US better for biliary pathology)
--see attached article on imaging in appendicitis

Clinical pearl: Heterotaxia or polysplenia: a heterogeneous disease that primarily affects the asymmetric organs, including the heart, lungs and bronchi, liver, intestines, and spleen. Primary manifestations of this disease include cyanotic congenital heart disease (in 80% of pts), biliary atresia, intestinal malrotation, and functional asplenia. The pathophysiology is not well understood, but appears to be an embryologic failure of development of R-->L asymmetry.

(Victoria Kelly MD, 8/17/10)