Appendicitis Differential Diagnoses

  • Author: Sandy Craig, MD; Chief Editor: Barry E Brenner, MD, PhD, FACEP   more...
 
Updated: May 16, 2012
 
 

Diagnostic Considerations

The overall accuracy for diagnosing acute appendicitis is approximately 80%, which corresponds to a mean false-negative appendectomy rate of 20%. Diagnostic accuracy varies by sex, with a range of 78-92% in male patients and 58-85% in female patients.

The classic history of anorexia and periumbilical pain followed by nausea, right lower quadrant (RLQ) pain, and vomiting occurs in only 50% of cases. Vomiting that precedes pain is suggestive of intestinal obstruction, and the diagnosis of appendicitis should be reconsidered.

The differential diagnosis of appendicitis is often a clinical challenge because appendicitis can mimic several abdominal conditions (see Differentials).[1] Patients with many other disorders present with symptoms similar to those of appendicitis, such as the following:

Other problems that should be considered in a patient with suspected appendicitis include appendiceal stump appendicitis, typhlitis, epiploic appendagitis, psoas abscess, and yersiniosis.

Misdiagnosis in women of childbearing age

Appendicitis is misdiagnosed in 33% of nonpregnant women of childbearing age. The most frequent misdiagnoses are PID, followed by gastroenteritis and urinary tract infection. In distinguishing appendiceal pain from that of PID, anorexia and onset of pain more than 14 days after menses suggests appendicitis. Previous PID, vaginal discharge, or urinary symptoms indicates PID. On physical examination, tenderness outside the RLQ, cervical motion tenderness, vaginal discharge, and positive urinalysis support the diagnosis of PID.

Although negative appendectomy does not appear to adversely affect maternal or fetal health, diagnostic delay with perforation does increase fetal and maternal morbidity. Therefore, aggressive evaluation of the appendix is warranted in pregnant women.

The level of urinary beta–human chorionic gonadotropin (beta-hCG) is useful in differentiating appendicitis from early ectopic pregnancy. However, with regard to the WBC count, physiologic leukocytosis during pregnancy makes this study less useful in the diagnosis than at other times, and no reliable distinguishing WBC parameters are cited in the literature.

Misdiagnosis in children

Appendicitis is misdiagnosed in 25-30% of children, and the rate of initial misdiagnosis is inversely related to the age of the patient. The most common misdiagnosis is gastroenteritis, followed by upper respiratory infection and lower respiratory infection.

Children with misdiagnosed appendicitis are more likely than their counterparts to have vomiting before pain onset, diarrhea, constipation, dysuria, signs and symptoms of upper respiratory infection, and lethargy or irritability. Physical findings less likely to be documented in children with a misdiagnosis than in others include bowel sounds; peritoneal signs; rectal findings; and ear, nose, and throat findings.

Considerations in elderly patients

Appendicitis in patients older than 60 years accounts for 10% of all appendectomies. The incidence of misdiagnosis is increased in elderly patients.

Older patients tend to seek medical attention later in the course of illness; therefore, a duration of symptoms in excess of 24-48 hours should not dissuade the clinician from the diagnosis. In patients with comorbid conditions, diagnostic delay is correlated with increased morbidity and mortality.

Differential Diagnoses

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Contributor Information and Disclosures
Author

Sandy Craig, MD  Residency Program Director, Carolinas Medical Center; Associate Professor, Department of Emergency Medicine, University of North Carolina at Chapel Hill School of Medicine

Sandy Craig, MD is a member of the following medical societies: Alpha Omega Alpha and Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

Coauthor(s)

Lutfi Incesu, MD  Professor, Department of Radiology, Ondokuz Mayis University School of Medicine; Chief, Neuroradiology, Department of Radiology, Ondokuz Mayis University Hospital, Turkey

Disclosure: Nothing to disclose.

Caroline R Taylor, MD  Associate Professor, Department of Diagnostic Radiology, Yale University School of Medicine; Chief, Diagnostic Imaging Service, Veterans Affairs Connecticut Health Care System

Caroline R Taylor, MD is a member of the following medical societies: Radiological Society of North America

Disclosure: Nothing to disclose.

Specialty Editor Board

William Lober, MD, MS  Associate Professor, Health Informatics and Global Health, Schools of Medicine, Nursing, and Public Health, University of Washington

Disclosure: Nothing to disclose.

Francisco Talavera, PharmD, PhD  Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Medscape Salary Employment

Eugene Hardin, MD, FAAEM, FACEP  Former Chair and Associate Professor, Department of Emergency Medicine, Charles Drew University of Medicine and Science; Former Chair, Department of Emergency Medicine, Martin Luther King Jr/Drew Medical Center

Disclosure: Nothing to disclose.

Eugene C Lin, MD  Attending Radiologist, Teaching Coordinator for Cardiac Imaging, Radiology Residency Program, Virginia Mason Medical Center; Clinical Assistant Professor of Radiology, University of Washington School of Medicine

Eugene C Lin, MD is a member of the following medical societies: American College of Nuclear Medicine, American College of Radiology, Radiological Society of North America, and Society of Nuclear Medicine

Disclosure: Nothing to disclose.

Chief Editor

Barry E Brenner, MD, PhD, FACEP  Professor of Emergency Medicine, Professor of Internal Medicine, Program Director for Emergency Medicine, Case Medical Center, University Hospitals, Case Western Reserve University School of Medicine

Barry E Brenner, MD, PhD, FACEP is a member of the following medical societies: Alpha Omega Alpha, American Academy of Emergency Medicine, American College of Chest Physicians, American College of Emergency Physicians, American College of Physicians, American Heart Association, American Thoracic Society, Arkansas Medical Society, New York Academy of Medicine, New York Academy of Sciences, and Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

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CT scan reveals an enlarged appendix with thickened walls, which do not fill with colonic contrast agent, lying adjacent to the right psoas muscle.
Sagittal graded compression transabdominal sonogram shows an acutely inflamed appendix. The tubular structure is noncompressible, lacks peristalsis, and measures greater than 6 mm in diameter. A thin rim of periappendiceal fluid is present.
Transverse graded compression transabdominal sonogram of an acutely inflamed appendix. Note the targetlike appearance due to thickened wall and surrounding loculated fluid collection.
Kidneys-ureters-bladder (KUB) radiograph shows an appendicolith in the right lower quadrant. An appendicolith is seen in fewer than 10% of patients with appendicitis, but, when present, it is essentially pathognomonic.
Technetium-99m radionuclide scan of the abdomen shows focal uptake of labeled WBCs in the right lower quadrant consistent with acute appendicitis.
Perforated appendicitis.
Normal appendix; barium enema radiographic examination. A complete contrast-filled appendix is observed (arrows), which effectively excludes the diagnosis of appendicitis.
Table 1. MANTRELS Score
Characteristic Score
M = Migration of pain to the RLQ1
A = Anorexia1
N = Nausea and vomiting1
T = Tenderness in RLQ2
R = Rebound pain1
E = Elevated temperature1
L = Leukocytosis2
S = Shift of WBCs to the left1
Total10
Source: Alvarado.[10]
RLQ = right lower quadrant; WBCs = white blood cells
Table 2. WBC Count and Likelihood of Appendicitis
WBC (× 10,000)Likelihood Ratio (95% CI)
4-70.10 (0-0.39)
7-90.52 (0-1.57)
9-110.29 (0-0.62)
11-132.8 (1.2-4.4)
13-151.7 (0-3.6)
15-172.8 (0-6.0)
17-193.5 (0-10)
19-22∞
Source: Dueholm et al.[15]
CI = confidence interval; WBC = white blood cell.
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