Appendicitis: Toward a better diagnosis
John, aged 47, had sudden onset of midabdominal pain and nausea. Examination at a local emergency department (ED) revealed a diffusely tender abdomen without rebound or guarding. The ED physician sent John home with an antiemetic and an H2 blocker. After a day, John's pain decreased, but he developed a low-grade fever. On re-evaluation, an abdominal CT scan showed a retrocecal appendix with a small abscess, indicating appendicitis with perforation.
Appendicitis results from obstruction and subsequent inflammation of the vermiform appendix. Accumulating secretions within the obstructed appendix lead to inflammation and ischemia, which can progress to necrosis and perforation. While appendicitis can occur at any age, it is most common in children and in people in their 20s and 30s.
When appendicitis presents with classic symptoms, diagnosis is not difficult. However, a number of patients present with atypical symptoms. Prompt recognition of these presentations is important for early diagnosis and treatment.1
Appendicitis as usual
The most common presentation of appendicitis is diffuse periumbilical or epigastric pain that subsequently localizes to the right lower quadrant. Focal, reproducible, and constant, the pain affects 95% of patients and increases in severity. The initial symptoms may be nonspecific, e.g., anorexia, nausea, indigestion, distension, bloating, and low-grade fever. Pain usually precedes any nausea and vomiting. If vomiting is the presenting symptom, other diagnoses should be seriously considered.
In 80% of cases, physical examination will reveal right lower- quadrant tenderness with guarding and rebound. Pain is localized at McBurney point, or 1.5-2 inches from the anterior superior iliac spine on a line from the spine to the umbilicus. Other important findings are positive psoas, obturator, and Rovsing signs, present in up to 80%-90% of cases.
A psoas or obturator sign is considered positive when contact between the psoas or the obturator muscle and the inflamed appendix elicits pain. Rovsing sign is positive when pain is felt with pressure at a point on the left side of the abdomen corresponding to McBurney point on the right.
Rectal examination will detect tenderness in the right lower quadrant in more than half of patients. When the appendix is retrocecal, the local signs of peritonitis are less common because the bowel may lie over the appendix.
Typical laboratory findings include leukocytosis. A WBC count >15,000/µL and/or a fever >101°F may signal a ruptured appendix. The urine may contain WBCs, RBCs, or both. All women of childbearing age suspected of having appendicitis should have a serum pregnancy test because pregnancy can affect both presenting signs and treatment.
Radiography has long been a mainstay in confirming or excluding appendicitis. Barium enema has been replaced by ultrasound and the more accurate CT scan. CT findings include peri-appendiceal fat stranding or abscess if perforation has occurred.2 Air in the appendix excludes appendicitis, but nonvisualization does not confirm appendicitis.
A scoring system of five criteria has been published to improve diagnostic accuracy. Immediate laparotomy is recommended for anyone who presents with four of the following: abdominal pain, vomiting, low-grade fever, WBC count >10,000/µL, or polymorphonuclear cells >75%.
Combining history, physical examination, blood studies, and radiologic tests will give an accurate diagnosis in 70%-80% of cases. Unfortunately, atypical presentations of appendicitis, like the one in our opener, can delay diagnosis and increase morbidity and mortality. John's sudden onset of pain should have been concerning and might have prompted earlier abdominal imaging. Typical right lower-quadrant pain is not present in all cases. Rather than being a sign of improvement, the decrease in John's pain may have coincided with perforation, with fever related to subsequent abscess formation.
Missed diagnosis is more common in children (likely due to communication difficulties in those younger than 3 years) and in those older than 60, who may delay seeking care. In the elderly and immunosuppressed, symptoms may be atypical or absent. In women, diagnosis may be made difficult by confounding gynecologic pathology and pregnancy.