med 18

 

also be present. The psoas sign is elicited if abdominal

pain is produced with extension of the right leg at the

hip while the patient lies on the left side. The obturator

test elicits pain with internal and external rotation of

the hip. Perforation should be suspected in patients with

generalized tenderness, rigidity, or a palpable mass in

the RLQ.

Up to one third of patients have atypical presentations of acute appendicitis, often owing to anatomic

variations. A retrocecal appendix can produce right

flank or pelvic pain, whereas malrotation of the colon

results in appendiceal transposition with LUQ pain.

Although pregnant women with appendicitis most commonly complain of RLQ pain, they can have RUQ tenderness owing to gravid uterine displacement of the

abdominal organs.

DIAGNOSTIC STUDIES

...... Laboratory

Individuals with acute appendicitis commonly have a

mild leukocytosis with a left shift, but a normal white

blood cell count (WBC) is not uncommon. An elevated

WBC and/or C- reactive protein can have a combined

sensitivity up to 98%, and normal values of both make

appendicitis very unlikely. Although hematuria or ster ­

ile pyuria can be present in acute appendicitis, isolated

microscopic hematuria may support a diagnosis of

renal colic, and pyuria can suggest pyelonephritis. A

negative pregnancy test should be documented in

females of childbearing age to rule out ectopic or heterotopic pregnancy.

..... Imaging

Early surgical consultation should be obtained before

imaging in straightforward cases of suspected appendicitis (ie, male with classic presentation and onset of pain

<48 hours). Plain radiography is not helpful. Abdominal

computed tomography (CT) should be obtained in nonpregnant females and males for whom the diagnosis is

unclear. CT has a sensitivity of >94% and a positive

predictive value of >95%. Many centers recommend CT

imaging with both IV and oral contrast, although noncontrast CT imaging is increasingly being used. Typical

findings include a dilated appendix >6 mm with a thickened wall, periappendiceal stranding, and visualization

of an appendicolith or abscess (Figure 2 7- 1). Luminal

obstruction may be relieved with perforation, leading to

disappearance of imaging hallmarks and difficulty visualizing the appendix. Patients with abdominal pain for

>48 hours usually require a CT scan to diagnose abscess

formation that is treated with percutaneous drainage

rather than surgery. Ultrasonography is the imaging

modality of choice in both pregnant females and

APPENDICITIS

Figure 27-1. CT sca n showing append icitis. Note the

increased uptake of intravenous contrast in the wall of

the appendix and the absence of oral contrast in the

lumen (a rrow) .

children. Typical findings include a thickened, noncompressible appendix >6 mm in diameter. Magnetic

resonance imaging is increasingly being used to diagnose appendicitis when ionizing radiation needs to be

avoided, although IV gadolinium should be avoided in

pregnancy and cannot be given to patients with renal

insufficiency.