Acute Appendicitis: Investigations
WBC CountStudies consistently show that 80-85% of adults with appendicitis have a white blood cell (WBC) count greater than 10,500 cells/µL. Neutrophilia greater than 75% occurs in 78% of patients. Less than 4% of patients with appendicitis have a WBC count less than 10,500 cells/µL and neutrophilia less than 75%.
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In infants and elderly patients, a WBC count is especially unreliable because these patients may not mount a normal response to infection. In pregnant women, the physiologic leukocytosis renders the CBC count useless for the diagnosis of appendicitis.
C Reactive Protein
C-reactive protein (CRP) is an acute-phase reactant synthesized by the liver in response to infection or inflammation and rapidly increases within the first 12 hours. CRP has been reported to be useful in the diagnosis of appendicitis; however, it lacks specificity and cannot be used to distinguish between sites of infection.
CRP levels of greater than 1 mg/dL are commonly reported in patients with appendicitis, but very high levels of CRP in patients with appendicitis indicate gangrenous evolution of the disease, especially if it is associated with leukocytosis and neutrophilia. However, CRP normalization occurs 12 hours after onset of symptoms.
CRP levels of greater than 1 mg/dL are commonly reported in patients with appendicitis, but very high levels of CRP in patients with appendicitis indicate gangrenous evolution of the disease, especially if it is associated with leukocytosis and neutrophilia. However, CRP normalization occurs 12 hours after onset of symptoms.
Urine Analysis
Urinalysis may be useful in differentiating appendicitis from urinary tract conditions. Mild pyuria may occur in patients with appendicitis because of the relationship of the appendix with the right ureter. Severe pyuria is a more common finding in urinary tract infections (UTIs).
Urinary β HCG
For women of childbearing age, the level of urinary beta–human chorionic gonadotropin (beta-hCG) is useful in differentiating appendicitis from early ectopic pregnancy.
Ultrasonography
Ultrasonography has been suggested as a safer primary diagnostic modality for appendicitis, with CT scanning used secondarily when ultrasonograms are negative or inconclusive.
A healthy appendix usually cannot be viewed with ultrasonography. When appendicitis occurs, the ultrasonogram typically demonstrates a noncompressible tubular structure of 7-9 mm in diameter.
Vaginal ultrasonography alone or in combination with transabdominal scan may be useful to determine the diagnosis in women of childbearing age, especially to exclude ovarian / adnexal pathology. One study of 22 pregnant women in the first and second trimesters showed that graded compression ultrasonography had a sensitivity of 66% and specificity of 95%.
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A healthy appendix usually cannot be viewed with ultrasonography. When appendicitis occurs, the ultrasonogram typically demonstrates a noncompressible tubular structure of 7-9 mm in diameter.
Vaginal ultrasonography alone or in combination with transabdominal scan may be useful to determine the diagnosis in women of childbearing age, especially to exclude ovarian / adnexal pathology. One study of 22 pregnant women in the first and second trimesters showed that graded compression ultrasonography had a sensitivity of 66% and specificity of 95%.
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CT scan
Computed tomography (CT) scanning with oral contrast medium or rectal Gastrografin enema has become the most important imaging study in the evaluation of patients with atypical presentations of appendicitis. Intravenous contrast is usually not necessary.
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Studies have found a decrease in negative laparotomy rate and appendiceal perforation rate when pelvic CT imaging was used in selected patients with suspected appendicitis.
(References)
Click here to see CT images
Studies have found a decrease in negative laparotomy rate and appendiceal perforation rate when pelvic CT imaging was used in selected patients with suspected appendicitis.
(References)
- Rao PM, Rhea JT, Rattner DW, et al. Introduction of appendiceal CT: impact on negative appendectomy and appendiceal perforation rates. Ann Surg. Mar 1999;229(3):344-9.
- McGory ML, Zingmond DS, Nanayakkara D, Maggard MA, Ko CY. Negative appendectomy rate: influence of CT scans. Am Surg. Oct 2005;71(10):803-8.
- Frei SP, Bond WF, Bazuro RK, Richardson DM, Sierzega GM, Reed JF. Appendicitis outcomes with increasing computed tomographic scanning. Am J Emerg Med. Jan 2008;26(1):39-44.
Diagnostic Laparoscopy
Diagnostic laparoscopy is a useful tool in evaluating patients with right lower abdominal pain, especially those with equivocal signs of acute appendicitis.
The use of Diagnostic Laparoscopy as a diagnostic modality is well established. Although CT scan and ultra sonography can be used to aid diagnosis, none of these are therapeutic modalities. Diagnostic Laparoscopy is also better than ultra sonography in the diagnosis of gynecological problems mimicking appendicitis. Women of childbearing age gain most from the procedure.
The use of Diagnostic Laparoscopy as a diagnostic modality is well established. Although CT scan and ultra sonography can be used to aid diagnosis, none of these are therapeutic modalities. Diagnostic Laparoscopy is also better than ultra sonography in the diagnosis of gynecological problems mimicking appendicitis. Women of childbearing age gain most from the procedure.