Septic arthritis laboratory findings: Difference between revisions

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==Laboratory Findings==
==Laboratory Findings==
=== Serum markers ===
Serum markers such as peripheral white cell count, erythrocyte sedimentation ratio, C-reactive protein are useful to determine infectious or inflammatory response and also useful to monitor therapeutic response. Absence of raise in these parameters may not be good correlate for the diagnosis of septic arthritis, as these tests are neither sensitive nor specific.<ref name="pmid11157138">Gupta MN, Sturrock RD, Field M (2001) [https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&retmode=ref&cmd=prlinks&id=11157138 A prospective 2-year study of 75 patients with adult-onset septic arthritis.] ''Rheumatology (Oxford)'' 40 (1):24-30. PMID: [https://pubmed.gov/11157138 11157138]</ref>
* '''Peripheral WBC count:''' Peripheral WBC count increases in septic arthritis, especially in children where as in adults it varies with severity.<ref name="pmid9375540">Jeng GW, Wang CR, Liu ST, Su CC, Tsai RT, Yeh TS et al. (1997) [https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&retmode=ref&cmd=prlinks&id=9375540 Measurement of synovial tumor necrosis factor-alpha in diagnosing emergency patients with bacterial arthritis.] ''Am J Emerg Med'' 15 (7):626-9. PMID: [https://pubmed.gov/9375540 9375540]</ref> It is not sensitive or specific to diagnose septic arthritis. 
* '''Erythrocyte sedimentation ratio:''' Patients with septic arthritis may have ESR > 30 mm/hr, but normal ESR may not ruleout septic arthritis.<ref name="pmid11157138">Gupta MN, Sturrock RD, Field M (2001) [https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&retmode=ref&cmd=prlinks&id=11157138 A prospective 2-year study of 75 patients with adult-onset septic arthritis.] ''Rheumatology (Oxford)'' 40 (1):24-30. PMID: [https://pubmed.gov/11157138 11157138]</ref>
* '''C- reactive protein:''' Elevated CRP of > 100 mg/L increased the likelihood of septic arthritis slightly.<ref name="pmid10225388">Söderquist B, Jones I, Fredlund H, Vikerfors T (1998) [https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&retmode=ref&cmd=prlinks&id=10225388 Bacterial or crystal-associated arthritis? Discriminating ability of serum inflammatory markers.] ''Scand J Infect Dis'' 30 (6):591-6. PMID: [https://pubmed.gov/10225388 10225388]</ref>
=== Synovial Fluid Analysis ===
Diagnosis of septic arthritis mainly depends on arthrocentesis and isolation of the pathogen from aspirated joint fluid.<ref name="pmid7355135">Bayer AS (1980) [https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&retmode=ref&cmd=prlinks&id=7355135 Gonococcal arthritis syndromes: an update on diagnosis and management.] ''Postgrad Med'' 67 (3):200-4, 207-8. PMID: [https://pubmed.gov/7355135 7355135]</ref> Clinical suspicion of joint sepsis should prompt for immediate synovial fluid aspiration. Septic arthritis should not be excluded even though the patient have low fever and normal WBC. The definitive diagnosis of septic arthritis requires identification of bacteria in the synovial fluid by Gram’s stain or by culture.<ref name="pmid9449882">Goldenberg DL (1998) [https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&retmode=ref&cmd=prlinks&id=9449882 Septic arthritis.] ''Lancet'' 351 (9097):197-202. [http://dx.doi.org/10.1016/S0140-6736(97)09522-6 DOI:10.1016/S0140-6736(97)09522-6] PMID: [https://pubmed.gov/9449882 9449882]</ref> If synovial fluid cannot be obtained with closed needle aspiration, the joint should be aspirated again with imaging guidance such as ultrasound guidance, computed tomography or fluoroscopic guidance.<ref name="pmid9449882">Goldenberg DL (1998) [https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&retmode=ref&cmd=prlinks&id=9449882 Septic arthritis.] ''Lancet'' 351 (9097):197-202. [http://dx.doi.org/10.1016/S0140-6736(97)09522-6 DOI:10.1016/S0140-6736(97)09522-6] PMID: [https://pubmed.gov/9449882 9449882]</ref> Synovial fluid analysis include:
* Synovial WBC count with differential
* Crystal analysis
* Gram stain
* Culture and sensitivity
Normal synovial fluid appears as clear, transparent, thick in viscosity with WBC count less than 200 mm3 and < 25% of PMN, where as in septic arthritis and other arthritis synovial fluid analysis will be as follows:<ref name="pmid3883171">Goldenberg DL, Reed JI (1985) [https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&retmode=ref&cmd=prlinks&id=3883171 Bacterial arthritis.] ''N Engl J Med'' 312 (12):764-71. [http://dx.doi.org/10.1056/NEJM198503213121206 DOI:10.1056/NEJM198503213121206] PMID: [https://pubmed.gov/3883171 3883171]</ref><ref name="pmid6415361">O'Brien JP, Goldenberg DL, Rice PA (1983) [https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&retmode=ref&cmd=prlinks&id=6415361 Disseminated gonococcal infection: a prospective analysis of 49 patients and a review of pathophysiology and immune mechanisms.] ''Medicine (Baltimore)'' 62 (6):395-406. PMID: [https://pubmed.gov/6415361 6415361]</ref><ref name="pmid2198352">Shmerling RH, Delbanco TL, Tosteson AN, Trentham DE (1990) [https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&retmode=ref&cmd=prlinks&id=2198352 Synovial fluid tests. What should be ordered?] ''JAMA'' 264 (8):1009-14. PMID: [https://pubmed.gov/2198352 2198352]</ref><ref name="pmid7993152">Wise CM, Morris CR, Wasilauskas BL, Salzer WL (1994) [https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&retmode=ref&cmd=prlinks&id=7993152 Gonococcal arthritis in an era of increasing penicillin resistance. Presentations and outcomes in 41 recent cases (1985-1991).] ''Arch Intern Med'' 154 (23):2690-5. PMID: [https://pubmed.gov/7993152 7993152]</ref><ref name="pmid7547108">Goldenberg DL (1995) [https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&retmode=ref&cmd=prlinks&id=7547108 Bacterial arthritis.] ''Curr Opin Rheumatol'' 7 (4):310-4. PMID: [https://pubmed.gov/7547108 7547108]</ref><ref name="pmid18508984">Mathews CJ, Kingsley G, Field M, Jones A, Weston VC, Phillips M et al. (2008) [https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&retmode=ref&cmd=prlinks&id=18508984 Management of septic arthritis: a systematic review.] ''Postgrad Med J'' 84 (991):265-70. [http://dx.doi.org/10.1136/ard.2006.058909 DOI:10.1136/ard.2006.058909] PMID: [https://pubmed.gov/18508984 18508984]</ref><ref name="pmid11171695">Jalava J, Skurnik M, Toivanen A, Toivanen P, Eerola E (2001) [https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&retmode=ref&cmd=prlinks&id=11171695 Bacterial PCR in the diagnosis of joint infection.] ''Ann Rheum Dis'' 60 (3):287-9. PMID: [https://pubmed.gov/11171695 11171695]</ref><ref name="pmid8185697">Liebling MR, Arkfeld DG, Michelini GA, Nishio MJ, Eng BJ, Jin T et al. (1994) [https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&retmode=ref&cmd=prlinks&id=8185697 Identification of Neisseria gonorrhoeae in synovial fluid using the polymerase chain reaction.] ''Arthritis Rheum'' 37 (5):702-9. PMID: [https://pubmed.gov/8185697 8185697]</ref>
{| border="1"
!colspan="1" style="background: #4479BA; text-align: center;" | {{fontcolor|#FFF|Type of
Arthritis}}
!colspan="1" style="background: #4479BA; text-align: center;" | {{fontcolor|#FFF|Color}}
!colspan="1" style="background: #4479BA; text-align: center;" | {{fontcolor|#FFF|Transparency}}
!colspan="1" style="background: #4479BA; text-align: center;" | {{fontcolor|#FFF|Viscosity}}
!colspan="1" style="background: #4479BA; text-align: center;" | {{fontcolor|#FFF|WBC count
(per mm3)}}
!colspan="1" style="background: #4479BA; text-align: center;" | {{fontcolor|#FFF|PMN
cellcount (%)}}
!colspan="1" style="background: #4479BA; text-align: center;" | {{fontcolor|#FFF|Gram stain}}
!colspan="1" style="background: #4479BA; text-align: center;" | {{fontcolor|#FFF|Gram Culture}}
!colspan="1" style="background: #4479BA; text-align: center;" | {{fontcolor|#FFF|polymerase chain reaction
(PCR) test}}
!colspan="1" style="background: #4479BA; text-align: center;" | {{fontcolor|#FFF|Crystals}}
|-
! Normal !! Clear !! Transparent !! High/thick !! < 200 !! < 25 !! Negative !! Negative !! Negative !! Negative
|-
!Gonococcal arthritis
!Yellow
!Cloudy-opaque
!Low
!34,000 to 68,000
!> 75
!Variable (< 50 percent)
!Positive (25 to 70 percent)
!Positive (> 75 percent)
!Negative
|-
!Non-gonococcal arthritis
!Yellowish-green
!Opaque
!Very low
!> 50,000 (> 100,000 is
more specific)
!> 75
!Positive (60 to
80 percent)
!Positive (> 90 percent)
!--
!Negative
|-
!Inflammatory:
crystalline arthritis
(e.g.Gout, Pseudo gout)
!Yellow
!Cloudy
!Low/thin
!2,000 to 100,000
!> 50
!Negative
!Negative
!Negative
!Positive
|-
!Inflammatory:
non-crystalline arthritis
(e.g. Rheumatoid arthritis, reactive arthritis)
!Yellow
!Cloudy
!Low/thin
!2,000 to 100,000
!> 50
!Negative
!Negative
!Negative
!Negative
|-
!Noninflammatory arthritis
(e.g. Osteoarthritis)
!Straw
!Translucent
!High/thick
!200 to 2,000
!< 25
!Negative
!Negative
!Negative
!Negative
|-
!Lyme arthritis
!Yellow
!Cloudy
!Low
!3,000 to 100,000
(mean: 25,000)
!> 50
!Negative
!Negative
!Positive (85 percent)
!Negative
|}
* Synovial fluid glucose level < 40 mg/dl and increased lactate level may represent septic arthritis, but these parameters are very less sensitive.<ref name="pmid485744">Sharp JT, Lidsky MD, Duffy J, Duncan MW (1979) [https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&retmode=ref&cmd=prlinks&id=485744 Infectious arthritis.] ''Arch Intern Med'' 139 (10):1125-30. PMID: [https://pubmed.gov/485744 485744]</ref><ref name="pmid2198352">Shmerling RH, Delbanco TL, Tosteson AN, Trentham DE (1990) [https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&retmode=ref&cmd=prlinks&id=2198352 Synovial fluid tests. What should be ordered?] ''JAMA'' 264 (8):1009-14. PMID: [https://pubmed.gov/2198352 2198352]</ref>
* Presence of crystals may not exclude septic arthritis, as the coexistant infection might be possible along with crystalline disease.<ref name="pmid2198352">Shmerling RH, Delbanco TL, Tosteson AN, Trentham DE (1990) [https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&retmode=ref&cmd=prlinks&id=2198352 Synovial fluid tests. What should be ordered?] ''JAMA'' 264 (8):1009-14. PMID: [https://pubmed.gov/2198352 2198352]</ref><ref name="pmid3735282">Baer PA, Tenenbaum J, Fam AG, Little H (1986) [https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&retmode=ref&cmd=prlinks&id=3735282 Coexistent septic and crystal arthritis. Report of four cases and literature review.] ''J Rheumatol'' 13 (3):604-7. PMID: [https://pubmed.gov/3735282 3735282]</ref>
The diagnosis of septic arthritis can be difficult as no test is able to completely rule out the possibility.
The diagnosis of septic arthritis can be difficult as no test is able to completely rule out the possibility.



Revision as of 14:33, 20 January 2017

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-In-Chief: Jumana Nagarwala, M.D., Senior Staff Physician, Department of Emergency Medicine, Henry Ford Hospital; Cafer Zorkun, M.D., Ph.D. [2]

Laboratory Findings

Serum markers

Serum markers such as peripheral white cell count, erythrocyte sedimentation ratio, C-reactive protein are useful to determine infectious or inflammatory response and also useful to monitor therapeutic response. Absence of raise in these parameters may not be good correlate for the diagnosis of septic arthritis, as these tests are neither sensitive nor specific.[1]

  • Peripheral WBC count: Peripheral WBC count increases in septic arthritis, especially in children where as in adults it varies with severity.[2] It is not sensitive or specific to diagnose septic arthritis.
  • Erythrocyte sedimentation ratio: Patients with septic arthritis may have ESR > 30 mm/hr, but normal ESR may not ruleout septic arthritis.[1]
  • C- reactive protein: Elevated CRP of > 100 mg/L increased the likelihood of septic arthritis slightly.[3]

Synovial Fluid Analysis

Diagnosis of septic arthritis mainly depends on arthrocentesis and isolation of the pathogen from aspirated joint fluid.[4] Clinical suspicion of joint sepsis should prompt for immediate synovial fluid aspiration. Septic arthritis should not be excluded even though the patient have low fever and normal WBC. The definitive diagnosis of septic arthritis requires identification of bacteria in the synovial fluid by Gram’s stain or by culture.[5] If synovial fluid cannot be obtained with closed needle aspiration, the joint should be aspirated again with imaging guidance such as ultrasound guidance, computed tomography or fluoroscopic guidance.[5] Synovial fluid analysis include:

  • Synovial WBC count with differential
  • Crystal analysis
  • Gram stain
  • Culture and sensitivity

Normal synovial fluid appears as clear, transparent, thick in viscosity with WBC count less than 200 mm3 and < 25% of PMN, where as in septic arthritis and other arthritis synovial fluid analysis will be as follows:[6][7][8][9][10][11][12][13]

Type of

Arthritis

Color Transparency Viscosity WBC count

(per mm3)

PMN

cellcount (%)

Gram stain Gram Culture polymerase chain reaction

(PCR) test

Crystals
Normal Clear Transparent High/thick < 200 < 25 Negative Negative Negative Negative
Gonococcal arthritis Yellow Cloudy-opaque Low 34,000 to 68,000 > 75 Variable (< 50 percent) Positive (25 to 70 percent) Positive (> 75 percent) Negative
Non-gonococcal arthritis Yellowish-green Opaque Very low > 50,000 (> 100,000 is

more specific)

> 75 Positive (60 to

80 percent)

Positive (> 90 percent) -- Negative
Inflammatory:

crystalline arthritis

(e.g.Gout, Pseudo gout)

Yellow Cloudy Low/thin 2,000 to 100,000 > 50 Negative Negative Negative Positive
Inflammatory:

non-crystalline arthritis

(e.g. Rheumatoid arthritis, reactive arthritis)

Yellow Cloudy Low/thin 2,000 to 100,000 > 50 Negative Negative Negative Negative
Noninflammatory arthritis

(e.g. Osteoarthritis)

Straw Translucent High/thick 200 to 2,000 < 25 Negative Negative Negative Negative
Lyme arthritis Yellow Cloudy Low 3,000 to 100,000

(mean: 25,000)

> 50 Negative Negative Positive (85 percent) Negative
  • Synovial fluid glucose level < 40 mg/dl and increased lactate level may represent septic arthritis, but these parameters are very less sensitive.[14][8]
  • Presence of crystals may not exclude septic arthritis, as the coexistant infection might be possible along with crystalline disease.[8][15]


The diagnosis of septic arthritis can be difficult as no test is able to completely rule out the possibility.

A number of factors should increase ones suspicion of the presence of an infection. In children these are: fever > 38.5 C, non weight bearing, serum WCBs > 12 x 10^9, ESR > 40 mm/hr, CRP > 20 mg/dL, a previous visit for the same.

Joint Fluid Aspiration

Diagnosis is by aspiration (giving a turbid, non-viscous fluid), gram stain and culture of fluid from the joint, as well as tell-tale signs in laboratory testing (such as a highly elevated neutrophils (approx. 90%), ESR or CRP). A proportion of patients with septic arthritis have little in the way of fever or raised ESR, although the CRP is usually raised.[16]

Gram Stain

The gram stain can rule in the diagnosis of septic arthritis however cannot exclude it.[17]

References

  1. 1.0 1.1 Gupta MN, Sturrock RD, Field M (2001) A prospective 2-year study of 75 patients with adult-onset septic arthritis. Rheumatology (Oxford) 40 (1):24-30. PMID: 11157138
  2. Jeng GW, Wang CR, Liu ST, Su CC, Tsai RT, Yeh TS et al. (1997) Measurement of synovial tumor necrosis factor-alpha in diagnosing emergency patients with bacterial arthritis. Am J Emerg Med 15 (7):626-9. PMID: 9375540
  3. Söderquist B, Jones I, Fredlund H, Vikerfors T (1998) Bacterial or crystal-associated arthritis? Discriminating ability of serum inflammatory markers. Scand J Infect Dis 30 (6):591-6. PMID: 10225388
  4. Bayer AS (1980) Gonococcal arthritis syndromes: an update on diagnosis and management. Postgrad Med 67 (3):200-4, 207-8. PMID: 7355135
  5. 5.0 5.1 Goldenberg DL (1998) Septic arthritis. Lancet 351 (9097):197-202. DOI:10.1016/S0140-6736(97)09522-6 PMID: 9449882
  6. Goldenberg DL, Reed JI (1985) Bacterial arthritis. N Engl J Med 312 (12):764-71. DOI:10.1056/NEJM198503213121206 PMID: 3883171
  7. O'Brien JP, Goldenberg DL, Rice PA (1983) Disseminated gonococcal infection: a prospective analysis of 49 patients and a review of pathophysiology and immune mechanisms. Medicine (Baltimore) 62 (6):395-406. PMID: 6415361
  8. 8.0 8.1 8.2 Shmerling RH, Delbanco TL, Tosteson AN, Trentham DE (1990) Synovial fluid tests. What should be ordered? JAMA 264 (8):1009-14. PMID: 2198352
  9. Wise CM, Morris CR, Wasilauskas BL, Salzer WL (1994) Gonococcal arthritis in an era of increasing penicillin resistance. Presentations and outcomes in 41 recent cases (1985-1991). Arch Intern Med 154 (23):2690-5. PMID: 7993152
  10. Goldenberg DL (1995) Bacterial arthritis. Curr Opin Rheumatol 7 (4):310-4. PMID: 7547108
  11. Mathews CJ, Kingsley G, Field M, Jones A, Weston VC, Phillips M et al. (2008) Management of septic arthritis: a systematic review. Postgrad Med J 84 (991):265-70. DOI:10.1136/ard.2006.058909 PMID: 18508984
  12. Jalava J, Skurnik M, Toivanen A, Toivanen P, Eerola E (2001) Bacterial PCR in the diagnosis of joint infection. Ann Rheum Dis 60 (3):287-9. PMID: 11171695
  13. Liebling MR, Arkfeld DG, Michelini GA, Nishio MJ, Eng BJ, Jin T et al. (1994) Identification of Neisseria gonorrhoeae in synovial fluid using the polymerase chain reaction. Arthritis Rheum 37 (5):702-9. PMID: 8185697
  14. Sharp JT, Lidsky MD, Duffy J, Duncan MW (1979) Infectious arthritis. Arch Intern Med 139 (10):1125-30. PMID: 485744
  15. Baer PA, Tenenbaum J, Fam AG, Little H (1986) Coexistent septic and crystal arthritis. Report of four cases and literature review. J Rheumatol 13 (3):604-7. PMID: 3735282
  16. Geirsson AJ, Statkevicius S, Víkingsson A (2008). "Septic arthritis in Iceland 1990-2002: increasing incidence due to iatrogenic infections". Ann Rheum Dis. 67 (5): 638–43. doi:10.1136/ard.2007.077131. PMID 17901088. Unknown parameter |month= ignored (help)
  17. "BestBets: Is a negative gram stain in suspected septic arthritis sufficient to rule out septic arthritis".


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