Appendicitis: Likelihood Ratios

Introduction: RLQ pain

nausea

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Tags: Gastrointestinal Problem Infection Physical Exam Tag this Diagnosis.

Differential Diagnoses include: Urinary Tract Infection

Prevalence

Population / Calculator	Prevalence	Comments / Study / Link
Adults >60 years old, abdominal pain in the ED	4%	http://jama.ama-assn.org/cgi/content/abstract/276/19/1589
Adults, abdominal pain in ambulatory setting	1%	http://jama.ama-assn.org/cgi/content/abstract/276/19/1589
Adults <60 years old, abdominal pain in ED	25%	http://jama.ama-assn.org/cgi/content/abstract/276/19/1589
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The likelihood ratios of findings for Appendicitis are listed below. See the left navigation bar to change the display.

Good Positive and Negative Likelihood Ratios

Finding	+LR	-LR	Comments, Study
Pain preceeding vomiting	2.8	0	Based on only one study Study: JAMA. 1996;276(19):1589-1594 http://jama.ama-assn.org/cgi/content/abstract/276/19/1589
Abdominal CT	18.8	0.1	Usually radiologists like the CTs to be done with rectal contrast. However, there may not be a sensitivity difference between with and without contrast; see PMID: 17456874, PMID: 16105539, though other studies disagree PMID: 17566826. Study: Ann Intern Med 2004 Oct 5;141(7):537-46. PMID 15466771
Abdominal US	4.5	0.2	Study: Ann Intern Med 2004 Oct 5;141(7):537-46. PMID 15466771
Appendicolith	4.6	0.4	By CT. In children Study: AJR Am J Roentgenol. 2000 Oct;175(4):981-4. PMID: 11000148
hearing loss Duplicate	3.2	0.4	Study: JAMA. 1996;276(19):1589-1594 http://jama.ama-assn.org/cgi/content/abstract/276/19/1589
Migration of Pain	3.6	0.4	Study: JAMA. 1996;276(19):1589-1594 http://jama.ama-assn.org/cgi/content/abstract/276/19/1589

Good Negative Likelihood Ratio

Finding	+LR	-LR	Comments, Study
RLQ Pain Duplicate	1.7	0.4	Study: JAMA. 1996;276(19):1589-1594 http://jama.ama-assn.org/cgi/content/abstract/276/19/1589
Guarding	1.7	0.5	Study: JAMA. 1996;276(19):1589-1594 http://jama.ama-assn.org/cgi/content/abstract/276/19/1589
No similar pain previously	1.4	0.5	Study: JAMA. 1996;276(19):1589-1594 http://jama.ama-assn.org/cgi/content/abstract/276/19/1589
Leukocytosis	1.6	0.5	>10k Study: Acad Emerg Med. 2004 Oct;11(10):1021-7. PMID: 15466143

Good Positive Likelihood Ratio

Psoas sign

3.2

0.9

With the patient in the supine position, ask the patient to lift the right thigh against your hand placed just above the knee. With the patient in left lateral decubitus position, extend the right leg at the hip.

Study: JAMA. 1996;276(19):1589-1594

http://jama.ama-assn.org/cgi/content/abstract/276/19/1589

Rebound

0.5

Study: JAMA. 1996;276(19):1589-1594

http://jama.ama-assn.org/cgi/content/abstract/276/19/1589

Poorly Diagnostic Findings

Finding	+LR	-LR	Comments, Study
Abdominal Rigidity	1.6	0.9	Study: JAMA. 1996;276(19):1589-1594 http://jama.ama-assn.org/cgi/content/abstract/276/19/1589
Rectal tenderness	1.8	0.8	Study: JAMA. 1996;276(19):1589-1594 http://jama.ama-assn.org/cgi/content/abstract/276/19/1589
hearing loss Duplicate	1.3	0.8	>99F Study: Acad Emerg Med. 2004 Oct;11(10):1021-7. PMID: 15466143
Emesis	0.9	1.1	Study: JAMA. 1996;276(19):1589-1594 http://jama.ama-assn.org/cgi/content/abstract/276/19/1589
Anorexia	1.1	0.9	Study: JAMA. 1996;276(19):1589-1594 http://jama.ama-assn.org/cgi/content/abstract/276/19/1589

Findings With Unspecified Accuracy

Finding	+LR	-LR	Comments, Study
Obturator sign	No accuracy specified.		Passively flex the right leg at the hip and knee and internally rotate the leg at the hip. Study: No studies but thought to be equivalent to psoas sign in accuracy.
Rovsing's Sign	No accuracy specified.		palpation of the lower left quadrant of a person's abdomen results in more pain in the right lower quadrant Study: no study specified.
RLQ Pain Duplicate	No accuracy specified.		Differential Diagnosis: Urinary Tract Infection Study: no study specified.