From the Guidelines
For suspected appendicitis in a 26-year-old, I recommend checking complete blood count (CBC), C-reactive protein (CRP), and urinalysis, as these tests are crucial in supporting the diagnosis and ruling out differential diagnoses, as suggested by the most recent evidence 1. The CBC often shows leukocytosis (elevated white blood cell count) typically between 10,000-18,000 cells/mm³ with neutrophil predominance. CRP is usually elevated above 1.0 mg/dL and rises with inflammation progression. Urinalysis helps rule out urinary tract conditions that can mimic appendicitis. Additional helpful tests include:
- Comprehensive metabolic panel to assess liver and kidney function
- Pregnancy test for females of reproductive age to rule out ectopic pregnancy While these laboratory tests support diagnosis, they should be interpreted alongside clinical presentation (right lower quadrant pain, fever, nausea) and imaging studies (ultrasound or CT scan), with CT scans having high diagnostic yield and sensitivity ranging from 85.7% to 100%, and specificity ranging from 94.8% to 100% 1. No single laboratory test can definitively diagnose appendicitis, but these tests collectively help confirm suspicion and rule out differential diagnoses. Elevated inflammatory markers with typical clinical presentation warrant surgical consultation for potential appendectomy, considering the historical perforation rates for men and women are 19.2% and 17.8%, respectively, and the association with increased morbidity, mortality, and length of stay 1.
From the Research
Laboratory Tests for Appendicitis
To diagnose appendicitis in a 26-year-old patient, several laboratory tests can be considered:
- Complete Blood Count (CBC) to check for signs of infection or inflammation, such as elevated white blood cell (WBC) count, neutrophil count, and neutrophil-to-lymphocyte ratio (NLR) 2, 3
- Urinalysis to rule out urinary tract infections or other conditions that may cause similar symptoms 4
- Basic metabolic panel to assess overall health and check for any electrolyte imbalances
- C-reactive protein measurement to evaluate the level of inflammation in the body
Rationale for Laboratory Tests
The use of laboratory tests in diagnosing appendicitis is supported by several studies:
- A study published in the Turkish Journal of Trauma & Emergency Surgery found that CBC parameters, such as WBC, neutrophil, and NLR, can be helpful in diagnosing acute appendicitis and measuring the severity of inflammation 2
- Another study published in the Archives of Academic Emergency Medicine found that neutrophil count and NLR had higher accuracy in predicting complicated appendicitis compared to other CBC parameters 3
- However, it's essential to note that laboratory tests should be used in conjunction with clinical evaluation, physical examination, and imaging studies to confirm the diagnosis of appendicitis 5, 4
Imaging Studies
In addition to laboratory tests, imaging studies such as computed tomography (CT) scans or ultrasonography may be ordered to confirm the diagnosis of appendicitis and assess for any complications: