Can Fluid Accumulation on Ultrasound Diagnose Necrotizing Fasciitis?

necrotizing fasciitis

Background

Necrotizing fasciitis (NF) is rapidly progressing, severe soft tissue infection with a mortality rate of 19.3% with treatment and significantly higher without treatment (1). Early diagnosis is essential to prompt surgical intervention and reduce morbidity and mortality. However, treatment can often be delayed because no laboratory or imaging test can definitively diagnose NF. Contrast-enhanced CT shows the best accuracy, but again is not perfect and can be difficult to obtain in unstable patients. MRI is similarly accurate, but even less feasible in the Emergency Department. Ultimately, it remains a surgical diagnosis.

Ultrasonography is a rapid, bedside, and non-invasive tool that has potential to accelerate assessment of patient with clinical suspicion for NF. There are ultrasonographic findings associated with NF diagnosis, including irregularity or thickening of deep fascia, subcutaneous emphysema, and fluid accumulation along the deep fascial plane (2-13). Considering this condition’s rapid progression, ultrasonography may enable physicians to quickly gauge disease severity and triage accordingly, prompting earlier surgery and bettering patient outcomes.

The Relationship Between Fluid Accumulation in Ultrasonography and Diagnosis and Prognosis of Patients with Necrotizing Fasciitis

 

Clinical Question

What is the relationship between ultrasonographic finding of fluid accumulation along the deep fascia and diagnosis and prognosis of necrotizing fasciitis?

What ultrasonographic findings are significantly different between NF patients and non-NF patients?

What is the ultrasonographic-detected depth of fluid accumulation along the deep fascia that offers the greatest accuracy to diagnosis of NF?

Is there a difference in the prognosis between NF patients with fluid accumulation compared to NF patients without fluid accumulation? 

Methods & Study Design

• Design 

Retrospective study with prospective enrollment

• Population 

This study was conducted at Chang Gung Memorial Hospital, a suburban academic tertiary care hospital.

Inclusion criteria: patients who visited the ED from February 2015 – November 2016 with clinical suspicion of NF of limbs based on symptoms and clinical signs (severe pain out of proportion, skin findings, rapid progression, crepitus, skin bullae, necrosis, or ecchymosis).

NF group: discharge diagnosis of NF, confirmed by pathology report showing necrosis after surgical intervention

Non-NF group: did not have surgical intervention or whose pathology report did not support NF diagnosis

Exclusion criteria: patients with ED visits between 24:00 – 7:00, non-lesion side also has fluid accumulation, age <18yo, prior antibiotics or debridement, lesions involving trunk area

• Intervention 

Ultrasonographic exam within 1 hour after ED arrival completed by one of three experienced emergency physicians who received an 8-hour basic and soft-tissue ultrasonographic training before the study

Orthopedic consult for surgical opinion

• Outcomes  

  • Diagnostic markers: irregularity or thickening of deep fascia, fluid accumulation, subcutaneous emphysema, subcutaneous cobblestone
  • Reasonable cutoff value of fluid accumulation along deep fascial plane for diagnosing NF according to receiving operating characteristic (ROC) curve
  • Prognostic markers: length of stay (LOS) in hospital, mortality, amputations, number of operations

Results

Ultrasound finding of fluid accumulation and irregular or thickened fascial layer were significantly different between NF and non-NF groups. All patients who had subcutaneous emphysema were in the NF group.

The best cutoff point of fluid accumulation to diagnose NF was 2mm, which had the best accuracy (72.7%), with sensitivity of 75%, a specificity of 70.2%, a positive predictive value of 71.7% and a negative predictive value of 72.7%.

NF patients with fluid accumulation had longer length of stay than NF patients without fluid accumulation (average: 39 days vs. 23 days). Number of operations were not significantly different between NF patients with and without fluid accumulation. All NF patients who had an amputation or died had fluid accumulation.

 

Overall mortality between NF and non-NF groups showed no significant difference.

Strength & Limitations

Strengths

  • Sample size was larger than other studies investigating ultrasonographic findings for NF diagnosis.
  • Study had a comparator groups with clear definitions (NF vs. non-NF).
  • Ultrasound training was standardized and assessed with inter-rater reliability between three emergency physicians as 100%.

Limitations

  • Small, imbalanced sample of NF patients for sensitivity and specificity analysis of fluid accumulation for amputation and mortality. 
  • Study excluded patients with truncal soft tissue infections.
  • Study excluded patients with prior antibiotics or debridement, which may have been NF patients with higher severity and worse prognosis.
  • Patient population were from south Taiwan exclusively.
  • NF patients had higher prevalence of specific co-morbidities (diabetes mellitus, liver cirrhosis, and alcohol use disorder), which could be confounding. 

Authors Conclusion

“The ultrasonographic finding of fluid accumulation along the deep fascia with a cutoff point of more than 2 mm of depth may aid in diagnosing NF. For the prognosis of NF, when fluid accumulation was present along deep fascia on ultrasound, patients with NF had longer lengths of hospital stays and were at risk of amputation or mortality. Ultrasonography is a point-of-care imaging tool that facilitates the diagnosis and prognosis of NF.” (14)

Our Conclusion

Consistent with prior studies and case reports (2-13), this study supports the role of ultrasound in the diagnosis of NF. Trained emergency physicians were able to successfully use ultrasound to detect significant imaging differences in NF patients, including fascial irregularity and deep fascial fluid accumulation. In comparison to Yen et al., this study suggests an even lower cutoff point of fluid accumulation along the deep fascia (2mm vs 4mm) for the highest diagnostic accuracy. We would caution that the finding of "fluid accumulation" was somewhat difficult to interpret in their study.

Further studies with larger sample sizes need to be completed. However, with the diagnostic and prognostic trends seen in this study, ultrasound should be considered as a timely, efficient imaging modality that can help identify patients with clinical suspicion of NF and accelerate OR intervention.

The Bottom Line 

Ultrasound is a viable imaging modality for patients with clinical suspicion of NF that could potentially expedite surgical intervention, though imaging findings may not be as easy to interpret as the authors lay out.

Authors

This post was written by Caresse Vuong, Charles Murchison MD and Amir Aminlari MD.

References

  1. Khamnuan P, Chongruksut W, Jearwattanakanok K, Patumanond J, Yodluangfun S, Tantraworasin A. Necrotizing fasciitis: Risk factors of mortality. Risk Manag Healthc Policy 2015;8:1–7.
  2. Castleberg E, Jenson N, Am Dinh V. Diagnosis of necrotizing fasciitis with bedside ultrasound: The STAFF exam. West J Emerg Med 2014;15:111–113.
  3. Tsai CC, Lai CS, Yu ML, Chou CK, Lin SD. Early diagnosis of necrotizing fasciitis by utilization of ultrasonography. Kaohsiung J Med Sci 1996;12:235–240.
  4. Wronski M, Slodkowski M, Cebulski W, Karkocha D, Krasnodebski IW. Necrotizing fasciitis: Early sonographic diagnosis. J Clin Ultrasound 2011;39:236–239.
  5. Yen ZS, Wang HP, Ma HM, Chen SC, Chen WJ. Ultrasonographic screening of clinically-suspected necrotizing fasciitis. Acad Emerg Med 2002;9:1448–1451.
  6. Bernardi, Emanuele, Antonello Iacobucci, Letizia Barutta, Elisa Pizzolato, Virna Olocco, and Bruno Tartaglino. “A-Lines in Necrotizing Fasciitis of the Lower Limb.” Journal of Ultrasound in Medicine 33, no. 11 (2014): 2044–46. 
  7. Chao, H. C., M. S. Kong, and T. Y. Lin. “Diagnosis of Necrotizing Fasciitis in Children.” Journal of Ultrasound in Medicine: Official Journal of the American Institute of Ultrasound in Medicine 18, no. 4 (April 1999): 277–81. 
  8. Hosek, William T., and Timothy C. Laeger. “Early Diagnosis of Necrotizing Fasciitis with Soft Tissue Ultrasound.” Academic Emergency Medicine 16, no. 10 (2009): 1033–1033. 
  9. Oelze, Lindsay, Stanley Wu, and Jennifer Carnell. “Emergency Ultrasonography for the Early Diagnosis of Necrotizing Fasciitis: A Case Series from the ED.” The American Journal of Emergency Medicine 31, no. 3 (March 1, 2013): 632.e5-632.e7. 
  10. Kehrl, Thompson. “Point-of-Care Ultrasound Diagnosis of Necrotizing Fasciitis Missed by Computed Tomography and Magnetic Resonance Imaging.” The Journal of Emergency Medicine 47, no. 2 (August 2014): 172–75. 
  11. Shyy, William, Roneesha S. Knight, Ruth Goldstein, Eric D. Isaacs, and Nathan A. Teismann. “Sonographic Findings in Necrotizing Fasciitis.” Journal of Ultrasound in Medicine 35, no. 10 (2016): 2273–77. 
  12. Hanif, Muhammad A., and Michael J. Bradley. “Sonographic Findings of Necrotizing Fasciitis in the Breast.” Journal of Clinical Ultrasound: JCU 36, no. 8 (October 2008): 517–19. 
  13. Valle Alonso, Joaquín, Ganapathiram Lakshmanan, and Yasser Saleem. “Use of POCUS Ultrasound in Sepsis, Bedside Diagnosis of Necrotizing Fasciitis.” QJM: An International Journal of Medicine 110, no. 10 (October 1, 2017): 687–88. 
  14. Lin, Chun-Nan, Cheng-Ting Hsiao, Chia-Peng Chang, Tsung-Yu Huang, Kuang-Yu Hsiao, Yi-Chuan Chen, and Wen-Chih Fann. “The Relationship Between Fluid Accumulation in Ultrasonography and the Diagnosis and Prognosis of Patients with Necrotizing Fasciitis.” Ultrasound in Medicine & Biology 45, no. 7 (2019): 1545–50. 

 

Bedside Ultrasound Identification of Infectious Flexor Tenosynovitis in the Emergency Department

flexor tenosynovitis

Background

Infectious flexor tenosynovitis (FTS) is a surgical emergency. If not treated promptly, infectious FTS carries significant morbidity including loss of function of fingers, necrosis of the tendon, and even digit amputation (1).

Infection can be caused in three ways: direct inoculation, contiguous spread, or hematogenous spread, as seen in cases of disseminated gonococcal infection. Tenosynovitis occurs when fluid collects between the visceral and parietal layer of the tendon, the most common location being in the hand and wrist.

Traditionally, diagnosis of infectious FTS is centered on the tetrad known as Kanavel’s signs (swelling of the finger, finger held in partially flexed position, pain on palpation of the flexor tendon, and pain on passive extension of the finger). While Kanavel’s signs are specific for infectious FTD, in a study of 41 participants with infectious FTS, only 54% of patients taken to the operating room (OR) had all of these signs (2). The gold standard of diagnosis remains surgical exploration and drainage. MRI can aid in the diagnosis of FTS, but this is rarely available in the ED. While radiographs may be obtained to look for trauma, osteomyelitis or a foreign body, they offer minimal to no additional benefit in diagnosing infectious FTS.   

This article presents a case of a 58-year-old man where point of care ultrasound (POCUS) identified tissue necrosis and fluid along the flexor tendon sheath of the hand, aiding in the rapid diagnosis of FTS, adding to the limited body of literature supporting use of POCUS for early diagnosis of infectious FTS.

Bedside Ultrasound Identification of Infectious Flexor Tenosynovitis in the Emergency Department

Clinical Question

Can point of care ultrasound be used in the emergency department to diagnose infectious FTS?

Methods & Study Design

• Design 

Case report.

• Population 

58 year old male with hypertension, diabetes and end stage renal disease.

• Intervention 

POCUS looking for fluid in flexor tendon sheath. Appropriate technique is shown in the image below, with a linear ultrasound probe placed on the palmar side of the wrist crease. Common findings of FTS are hypoechoic or anechoic fluid surrounding the flexor tendons.

ultrasound flexor tendons
Padrez et al. West J Emerg Med 2015, 16(2)

• Outcomes  

Accurate diagnosis of FTS

 

Results

The physicians found a moderate amount of fluid and echogenic material within the tendon sheath, as noted in the image below. Orthopedics was consulted and patient was started on broad spectrum antibiotics and taken to the operating room. They found extensive pus within the flexor tendon sheath and cultures grew Staph aureus

 

ultrasound flexor tenosynovitis
Padrez et al. West J Emerg Med 2015, 16(2)

Strength & Limitations

The POCUS exam the authors describe is practical and useful. This could feasibly be performed by clinicians with relatively little ultrasound training. As mentioned, FTS is a surgical emergency and remains largely a clinical diagnosis, so any modality that helps bring more certainty to the diagnosis, and lead to quicker definitive treatment, is welcome.

It is unclear what the level of ultrasound training was for the physicians who performed this exam. Another note, it may be difficult to distinguish rheumatologic from infectious causes of tenosynovitis using ultrasound, so clinical context is always important. They also mentioned this can only aid in increasing your suspicion for FTS, it cannot be used to rule it out. 

Authors Conclusion

POCUS may be an ideal adjunct for the ED physician in the evaluation of a patient with suspected infectious FTS 

Our Conclusion

We agree with the authors conclusions that POCUS can be a useful adjunct to clinical exam in diagnosing FTS, with the understanding that POCUS cannot rule out FTS or distinguish rheumatologic from infectious process.

The Bottom Line 

POCUS can be a useful adjunct to clinical exam in diagnosing FTS. Use the linear probe and place at the palmar side of the wrist crease, look for hypoechoic or anechoic material around the flexor tendons with possible thickening of the tendon itself. 

Authors

This post was written by Betial Asmerom and Amir Aminlari MD. Edited by Charles Murchison MD.

References

  1. Mamane, W. et al. Infectious flexor hand tenosynovitis: State of knowledge. A study of 120 cases. J. Orthop. 15, 701–706 (2018).
  2.  
  3. Hubbard, D., Joing, S. & Smith, S. W. Pyogenic Flexor Tenosynovitis by Point-of-care Ultrasound in the Emergency Department. Clin. Pract. Cases Emerg. Med. 2, 235–240 (2018).
  4.  
  5. Padrez et al. Bedsound Ultrasound Identification of Infectious Flexor Tenosynovitis in the Emergency Department. West J Emerg 2015. 16 (2). 

 

 

Case # 14: Whirlpool swirling, twisting and turning

A 13-year-old male presents to the emergency department with right testicular pain for one-hour duration. The pain began while having a bowel movement. He had no nausea or vomiting. His exam is notable for a high riding right testicle and tenderness to palpation over the right testicle.

Vitals: T: 97.8, HR: 106, BP: 135/79, RR: 16, Sat: 96% on RA

A bedside ultrasound of the testicles is performed. What do you see?

Answer and Learning Points

Answer

These ultrasound images demonstrates limited flow into the right testicle suggestive of testicular torsion. Manual detorsion was performed at the bedside using the “open-the-book” maneuver with subsequent ultrasound demonstrating return of flow to the right testicle. Urology was consulted, and the patient was scheduled for an outpatient orchiopexy.

Learning Points

The acute scrotum is a presentation that requires timely evaluation and management by the emergency physician. Of all causes of acute scrotum, testicular torsion is the diagnosis that requires the most emergent action because of the limited time window of testicular salvageability.1 Unfortunately, in many clinical settings including urgent cares, clinics, and rural community emergency rooms, it can be challenging to confirm our clinical suspicion in a timely fashion because of the difficulty in obtaining an official scrotal ultrasound. For this reason, POCUS is an important tool for emergency physicians in the diagnosis of patients with acute scrotum.

Ultrasound findings of testicular torsion:

Loss or reduction of color Doppler flow/Spectral Doppler tracings to affected testicle (Must compare to other testicle)

Affected testicle becomes more heterogeneous than other testicle

Adhikari, S. R. (2008). Small parts - Testicular ultrasound. Retrieved from https://www.acep.org/sonoguide/smparts_testicular.html

Thickened, hypoechoic mediastinum

Prando D. Torsion of the spermatic cord: the main gray-scale and doppler sonographic signs. Abdom Imaging. 2009 Sep-Oct;34(5):648-61. doi: 10.1007/s00261-008-9449-8. Review. PubMed PMID: 18709404. 

Whirlpool sign6

Author

Marissa Wolfe, MS4; Amir Aminlari, MD, Emergency Ultrasound Fellowship Director at UCSD

References

  1. Mellick LB, Sinex JE, Gibson RW, Mears K. A Systematic Review of Testicle Survival Time After a Torsion Event. Pediatr Emerg Care. 2017 Sep 25. doi: 10.1097/PEC.0000000000001287. [Epub ahead of print] PubMed PMID: 28953100.
  2. Sharp VJ, Kieran K, Arlen AM. Testicular torsion: diagnosis, evaluation, and management. Am Fam Physician. 2013 Dec 15;88(12):835-40. Review. PubMed PMID: 24364548.
  3. Wang S, Scoutt L. Testicular torsion and manual detorsion. Ultrasound Q. 2013 Sep;29(3):261-2. doi: 10.1097/RUQ.0b013e3182a2d129. PubMed PMID: 23945494.
  4. Adhikari, S. R. (2008). Small parts - Testicular ultrasound. Retrieved from https://www.acep.org/sonoguide/smparts_testicular.html
  5. Prando D. Torsion of the spermatic cord: the main gray-scale and doppler sonographic signs. Abdom Imaging. 2009 Sep-Oct;34(5):648-61. doi: 10.1007/s00261-008-9449-8. Review. PubMed PMID: 18709404.
  6. Kalfa N, Veyrac C, Lopez M, Lopez C, Maurel A, Kaselas C, Sibai S, Arena F, Vaos G, Bréaud J, Merrot T, Kalfa D, Khochman I, Mironescu A, Minaev S, Avérous M, Galifer RB. Multicenter assessment of ultrasound of the spermatic cord in children with acute scrotum. J Urol. 2007 Jan;177(1):297-301; discussion 301. PubMed PMID: 17162068.
  7. Vijayaraghavan SB. Sonographic differential diagnosis of acute scrotum: real-time whirlpool sign, a key sign of torsion. J Ultrasound Med. 2006 May;25(5):563-74. PubMed PMID: 16632779.

Case # 10: A Mechanical Issue

A 32 year old male was carrying a heavy pipe overhead with his right arm and slipped falling forward, onto the right side. He notes pain in the right shoulder, worse with any movement. His right arm is flexed and internally rotated for comfort.

Vitals: T 98.6 HR 95 BP 143/91  RR 14 O2 98% on RA

A bedside ultrasound of the right shoulder is performed, what is the next best step in management?

Screen Shot 2017-11-18 at 11.09.45 AM

Answer and Learning Points

Answer

Shoulder dislocation reduction. The ultrasound image shows anterior displacement of the humeral head with respect to the glenoid fossa consistent with an anterior shoulder dislocation. A hematoma is also noted within the joint space which is very commonly associated with a traumatic shoulder dislocation. 

Ultrasound diagnosis of anterior shoulder dislocation

Learning Points

    • Ultrasound is useful for both the initial diagnosis and reduction confirmation of a shoulder dislocation, as well as for intra-articular injection of local anesthetic; however in a traumatic dislocation, an initial x-ray should be obtained to evaluate for any associated fracture.
    • To perform the exam, a low frequency curvilinear transducer should be used. The operator should stand behind the patient, on the side of the affected shoulder, and place the ultrasound system directly in front of the patient for easy visualization. The probe should be placed on the posterior aspect of the scapula, parallel and just inferior to the scapular spine. This will allow direct visualization of the glenohumeral joint.
  • Proper probe placement for evaluation of glenohumeral joint.
    • In a normal shoulder the glenoid and humeral head articulate nicely and this can be appreciated on ultrasound with internal and external rotation of the patient's arm, however with dislocation, the humeral head and glenoid will not be aligned. In anterior dislocation, the humeral head will be deep to the glenoid, while in a posterior dislocation, the humeral head will be more superficial to the glenoid.
  • Normal glenohumeral ultrasound anatomy
    • Ultrasound is especially useful to confirm successful shoulder relocation and prevent both a prolonged stay in the emergency department waiting for a post reduction x-ray, as well as re-sedation if this was required for a difficult shoulder reduction.
    • Lastly, this same ultrasound view can be used for in-plane needle guidance to provide intra-articular anesthesia using a lateral needle entry approach.
    • For a 5 minute video tutorial on  ultrasound for shoulder dislocation , click here to watch this excellent video at 5 Minute Sono.
In vivo shoulder reduction!

Case # 8: A Case of Comparision

A 40 year old male presents to the emergency department with pain to the entire right thumb and wrist for 1 day.  He notes that he suffered a small puncture wound to his right thumb 1 day ago while working on his car.  The patient has notable circumferential, non-erythematous swelling to his right thumb with tenderness along the flexor tendon. There is also fullness of the dorsum of his wrist. He is holding his fingers flexed and has pain radiating into the wrist with any movement of his fingers or wrist, especially with extension of his fingers.

Vitals: T 98.7 HR 90 BP 132/81  RR 13 O2 98% on RA

A bedside ultrasound is performed, what is the next best step in management?

Normal Left Thumb in Long Axis

Normal Left Thumb in Long Axis

Abnormal Right Thumb in Long Axis

Abnormal Right Thumb in Long Axis

Answer and Learning Points

Answer

Empirical antibiotic therapy and orthopedic surgery consultation for infectious flexor tenosynovitis (FTS).  The patient meets 4 out of 4 Kanavel's signs and has ultrasound evidence of FTS suggested by a thickened tendon with surrounding anechoic fluid.

Short Axis View of Right 1st Digit demonstrating hypoechoic fluid surrounding tendon.

Learning Points

    • FTS is often a clinical diagnosis and examination (Kanavel's signs) is thought to have high sensitivity (91.4-97.1%) but low specificity (51.3-69.2%) for infectious FTS [2]; however a negative exam does not rule it out completely.
      • Kanavel's signs include:
        • Finger held in slight flexion
        • Fusiform swelling
        • Tenderness along the flexor tendon sheath
        • Pain with passive extension of the digit
    • FTS is treated with empirical antibiotic  therapy as well as early surgical debridement and drainage. Delays in diagnosis can lead to local spread of infection, compartment syndrome and necrosis.
    • While there is not high quality evidence describing the use of emergency department point of care ultrasound (POCUS) to diagnose FTS, previous radiographic studies have found ultrasound to be more sensitive than clinical exam for detecting tenosynovitis [3].
    • Common ultrasound findings for FTS include:
      • Hypoechoic or anechoic edema or debris within the tendon sheath
      • +/- thickening of the tendon sheath
    • The ultrasound examination should be performed using a linear probe, examining the affected tendon (and normal tendon on other hand for comparison), in both the longitudinal and transverse plane.
      • Small rocking or fanning motions should be used to ensure perpendicular orientation of the probe to the tendon to avoid artifact secondary to anisotropy.
    • As in all uses of POCUS in the emergency department setting, findings should be interpreted in conjunction with clinical examination and history when evaluating for infectious FTS. We believe POCUS for infectious FTS can be used to increase diagnostic certainty and even expedite care and aggressive treatment however a normal exam should not be used to rule out this diagnosis.

Author

This post was written by Michael Macias, MD, Ultrasound Fellow at UCSD.

References

    1. Padrez, K., Bress, J., Johnson, B., & Nagdev, A. (2015). Bedside Ultrasound Identification of Infectious Flexor Tenosynovitis in the Emergency Department. Western Journal Of Emergency Medicine, 16(2), 260-262. doi:10.5811/westjem.2015.1.24474
    2. Kennedy CD, e. (2017). Differentiation Between Pyogenic Flexor Tenosynovitis and Other Finger Infections. - PubMed - NCBI . Ncbi.nlm.nih.gov. Retrieved 21 October 2017, from https://www.ncbi.nlm.nih.gov/pubmed/28720000
    3. Hmamouchi I, Bahiri R, Srifi N, et al. A comparison of ultrasound and clinical examination in the detection of flexor tenosynovitis in early arthritis. BMC Musculoskelet Disord. 2011;12(1):91.