bubble of trouble…

the case.

76 year old male presents to your Emergency Department via ambulance with right hip pain and a fever of 38.1*C.

He reports a week long history of worsening right hip and buttock pain which is now significantly reducing his ability to both mobilise and weight bear. His pain is exacerbated by sitting down. There has been associated night sweats for the past 48 hours and he has experienced rigors this morning. He has had no falls and no recent trauma.

The patient had seen his GP for this problem 3 days earlier. The subsequent physiotherapy session only seemed to worsening his symptoms.

He has bought in an outpatient ultrasound which suggests “tendonitis” or “bursitis” as the cause of his symptoms.

Past Medical History.

  • Benign prostatic hypertrophy
  • Rectal Cancer with resection (10 years ago)
  • Renal cell carcinoma with right-sided nephrectomy (12 years ago)
  • Appendicectomy

Medications include a beta-blocker and a PPI.

On examination.

Looks very well and is comfortable at rest lying on his left side. He is however febrile to 38.1*C.

  • A: patent & protected
  • B: Sat 95% RA, no resp distress. RR 16/min. Chest clear.
  • C: Warm & well perfused. P 124/min, BP 122/64, Heart sounds dual (without murmurs or rub), JVP not elevated, no peripheral oedema.
  • D: GCS 15, PEARL 5mm, moving all 4 limbs.
  • E: Febrile. BSL 8.1. Warm, tender & erythematous (likely cellulitic area) extending from the popliteal fossa proximally towards the gluteal region. Significantly reduced hip flexion & extension secondary to pain. Knee range-of-motion, unremarkable.

You pause & ask yourself…

[DDET What are your differential diagnoses at this stage?]

  • Infectious/Sepsis:
    • Cellulitis
    • Septic arthritis
    • Osteomyelitis
    • Soft tissue abscess/collection
    • Retroperitoneal/psoas abscess
    • Spinal
  • Inflammatory:
    • Bursitis
    • Tendonitis
  • Myositis
  • Rhabdomyolysis
  • Malignancy
    • +/- pathological fracture/bony infiltrate
  • Radiculopathy (sciatica)
  • ?dual pathology…


[DDET Here is his venous blood gas…]


[DDET Your interpretation?]

Surprisingly unhelpful given the clinical context.

Are you reassured by the normal lactate?



[DDET Here are the remainder of his blood results]

nf-fbc nf-biochem nf-crp

[DDET Your interpretation?]

Supportive of the clinical picture of sepsis.
– Elevated WCC, predominate neutrophilia & significantly elevated CRP.

Moderate renal impairment.
– Elevated creatinine & urea
– ?Acute versus chronic in a patient with single kidney & previous bladder outlet obstruction.



[DDET What is your initial management in this patient?]

  • Take cultures
  • Empiric, early broad-spectrum antibiotic administration
    • Flucloxacillin 2g q4-6h
    • Gentamicin (5-7mg/kg of ideal body weight)
  • IV fluids
    • Guided by systemic perfusion, pulse-rate, blood pressure, capillary return & hourly urine output.
  • Strict fluid balance
  • Analgesia
  • Antipyretics


[DDET Whilst the antibiotics are trickling in, you go back & reexamine your patient…]

… this time you notice that there is marked subcutaneous emphysema beneath the previously mentioned area of painful erythema !!!

Whilst you organise an urgent portable xray of the affected area, you decide to use your ultrasound to scan his leg…

[DDET What does it show??]

This scan reveals various areas of
(1) soft tissue cobblestoning consistent with cellulitis (subcutaneous oedema)
(2) subcutaneous/fascial hypoechoic fluid collection
(3) subcutaneous emphysema with scatter artefact

Subcutaneous gas concerning for necrotising soft tissue infection
Subcutaneous gas concerning for necrotising soft tissue infection

This is what normal soft tissue should look like…



[DDET His knee xray confirms your suspicion…]

Diffuse subcutaneous emphysema extending medially & laterally, above & below the knee joint.


[DDET What are you going to do now?]

  • Transfer to a higher acuity area (monitored bed, resuscitation bay)
  • Administration of targeted broad-spectrum antibiotics
    • Meropenum 1g IV q8h plus
    • Clindamycin 600mg IV q8h
  • Aggressive fluid resuscitation with targeted early-goal directed therapy of sepsis
  • Immediate surgical bedside review for emergency debridement & source control
  • Tetanus prophylaxis


[DDET & the surgeon comes to the bedside…]

With the history of rectal cancer, surgical anastomosis & an indolent, week-long presentation they request an urgent CT of this patients’ abdomen & leg.

Here is his CT…

[DDET Formal CT report…]

  1. Contained perforation of the rectum around the site of anastomosis with associated collection of faeculent material in the pre-sacral space.
  2. Gas extending from the collection via the right ischioanal fossa to the right leg.
    Gas in the right leg is subcutaneous as well as intra-fascial.
  3. Sacral bony changes could be related to the previous radiation therapy or represent sacral osteomyelitis.



[DDET The diagnosis]

Necrotising Fasciitis

In this case, secondary to rectal perforation complicated by a pelvic abscess & sacral osteomyelitis.

Necrotising soft tissue infections are a spectrum of illnesses characterised by fulminant, extensive soft-tissue necrosis, systemic toxicity & a high mortality (25-30%). Incorporated into this group are Fournier gangrene, necrotising fasciitis & gas-gangrene.

Risk factors:

  • Advanced age
  • Diabetes
  • Alcoholism
  • Peripheral vascular disease
  • Immunosuppression
  • Heart disease
  • Renal failure
  • HIV
  • Malignancy
  • Aspirin & NSAID use
  • Decubitus ulcers
  • Chronic skin conditions
  • IV drug use

Note: ~ half of all known cases of streptococcal necrotising fasciitis occur in young, previously healthy individuals.

Classification (Microbiology).

Classification of Necrotising Soft Tissue Infections. Courtesy of Misiakos et al (2014).


  • Rapid necrotising process begins with direct invasion of subcutaneous tissue from external trauma (IVDU, surgical incision, abscess, insect bite) or from direct spread from a perforated viscous (usually colon, rectum or anus).
  • Spontaneous development is rare.
  • Bacteria proliferate & invade subcutaneous tissue and deep fascia leading to release of exotoxins that lead to tissue ischaemia, liquefaction necrosis and systemic toxicity.
  • Tissue ischaemia produced in all such infections impedes immune system destruction of bacteria & prevents adequate delivery of antibiotics. Antibiotics are therefore rarely effective and immediate surgical intervention remains the cornerstone of successful management

Clinical Features.

Classically, patients have tissue pain, fever & diaphoresis. They will often have a tachycardia out of proportion to their fever. Only ~10-40% of the time do patients report trauma or a break in the skin 48 hours prior to presentation.

Pain out of proportion to clinical findings is perhaps the most important feature to help make the diagnosis early. Not all patients have severe pain though…

Brawny oedema & crepitus may be present at the painful area.

Haemorrhagic bullae & malodorous “dirty dishwater” discharge may also be present.

Haemorrhagic bullae – Courtesy of Medscape (Group A Streptococcal Infections)


The diagnosis of necrotising fasciitis is a CLINICAL one.

X-ray may show subcutaneous gas but CT is more sensitive and can demonstrate fascial thickening and oedema with deep tissue collection and gas formation (no additional benefit with IV contrast). MRI has best sensitivity but usually relates to delay to diagnosis/treatment.

The Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) incorporates six routine laboratory tests (haemoglobin, creatinine, glucose, sodium, CRP & white blood cell count) into a weighted 13-point score. This was a retrospectively derived scoring tool designed to aid in the bedside diagnosis of necrotising fasciitis. Using a cut-off of ≥6 points, the score was initially validated in a small cohort, yielding a sensitivity of 90% & specificity of 95%. There are no prospective studies evaluating LRINEC performance. Systematic reviews of mostly retrospective studies have concluded that clinical suspicion is superior to laboratory testing or the LRINEC score.


  • Aggressive fluid resuscitation & early goal-directed therapy of sepsis
  • Early IV Antibiotics.
    • The Therapeutic Guidelines here in Australia recommend;
      Meropenem 1g IV q8h plus either Clindamycin or Lincomycin 600mg IV q8h.
  • Immediate surgical review for emergent debridement (source control) in the operating theatre remains the gold standard.
  • Provide tetanus prophylaxis
  • Supportive care
  • Later wound management & reconstruction.
  • Therapeutic controversies:
    • Hyperbaric oxygen
    • IV Ig


[DDET Case conclusion & outcome]

Our patient is taken from ED to the operating theatre shortly after the CT scan was obtained. Here he undergoes an exploratory laparotomy, formation of a colostomy and pelvic washout with simultaneous debridement of the right leg.

He has a reasonably stable post-operative course in the ICU & later returns to theatre for incision & drainage of his presacral abscess.

He continues to make a slow but progressive recovery and is discharged home on long-term antibiotics under the guidance of Infectious Diseases.


[DDET References & Credits]


  1. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide. 7th Edition.
  2. Rosenʼs Emergency Medicine. Concepts and Clinical Approach. 7th Edition
  3. Machado NO. Necrotizing fasciitis: The importance of early diagnosis, prompt surgical debridement and adjuvant therapy. North Am J Med Sci 2011; 3: 107-118.
  4. Sadasivan J, Maroju NK, Balasubramaniam A. Necrotizing Fasciitis. Indian Journal of Plastic Surgery : Official Publication of the Association of Plastic Surgeons of India. 2013;46(3):472-478. doi:10.4103/0970-0358.121978. PubMed.
  5. Puvanendran R, Huey JCM, Pasupathy S. Necrotizing fasciitis. Canadian Family Physician. 2009;55(10):981-987. PubMed.
  6. Krieg A, Röhrborn A, Schulte am Esch J, et al. Necrotizing fasciitis: microbiological characteristics and predictors of postoperative outcome.European Journal of Medical Research. 2009;14(1):30-36. doi:10.1186/2047-783X-14-1-30. PubMed.
  7. Misiakos EP, Bagias G, Patapis P, Sotiropoulos D, Kanavidis P, Machairas A. Current Concepts in the Management of Necrotizing Fasciitis. Frontiers in Surgery. 2014;1:36. doi:10.3389/fsurg.2014.00036. PubMed.
  8. Cheng N-C, Tai H-C, Chang S-C, Chang C-H, Lai H-S. Necrotizing fasciitis in patients with diabetes mellitus: clinical characteristics and risk factors for mortality. BMC Infectious Diseases. 2015;15:417. doi:10.1186/s12879-015-1144-0. PubMed.
  9. Hakkarainen TW, Kopari NM, Pham TN, Evans HL. Necrotizing soft tissue infections: Review and current concepts in treatment, systems of care, and outcomes. Current problems in surgery. 2014;51(8):344-362. doi:10.1067/j.cpsurg.2014.06.001. PubMed.
  10. Jeng, K. Necrotizing Fasciitis via HQMedEd.com. 2015.

Author: Julie Nguyen
Web editing + additional writing: Chris Partyka


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