Thread by @GregoryMansour

Hey all, time for another Urology tweetorial on Fournier gangrene (FG). We will briefly cover the history, epidemiology, pathophysiology, and management. Special thanks in advance to my wonderful mentor @RamonVirasoro! #UroSoMe

The first documented case of FG is from 800 BC by an Arab physician Avicenna who practiced in Uzbekistan. He identified perineal gangrene as a complication of transperineal bladder stone removals (impressive that they were doing these).

FG first documented in modern history was by Dr. Baurienne(1764) in France in which he described a boy gored by an ox in the scrotum.

Dr. Jean Alfred Fournier (1883) identified risk factors such as diabetes and alcoholism in young men and had the disease process named after him. Fournier was chief of diseases of the skin at a hospital in Paris and was a leading syphololigst in his day.

By some estimates FG comprises 0.02% of hospitalizations in the US with an average incidence of 1.6/100,000 in males. Risk factors include factors that affect either microcirculation or immune status: diabetes, obesity, smoking, alcoholism, renal/liver failure, malignancy, HIV.

Most commonly this is a polymicrobial infection. Interestingly, the highest rates of Type III necrotizing soft tissue infections are highest in Asia due to the high consumption of seafood.

One of the hallmark characteristics of FG is the synergistic effects of anaerobic/aerobic bacteria. Collectively, collagenase, heparinase, hyaluronidase, streptokinase breakdown tissue planes and allow for rapid spread. Microvascular thrombosis occurs leading to tissue ischemia.

Mortality predictors:

Increasing age (OR 4.0-18.8)
HTN: (OR 1.5)
Heart failure (OR 3.7)
Renal Failure (OR 5.3)
Coagulopathy (OR 4.4)
Hospitals treating more than one FG case per year decreased mortality by 42-84%
Overall Mortality: 0-42%

Management:

Management includes hemodynamic support, broad spectrum antibiotics, and surgical debridement. The infection spreads along the Colles fascia in the Perineum, dartos in the scrotum, and Scarpa in the abdominal wall and has been noted to spread as high as 2-3 cm/hr.

Debridement within the first twelve hours of admission significantly improves outcomes (HR:0.064; P = 0.0379). Repeat debridement should be scheduled within 24 hours to assess for progression.

Multiple scores have been developed to determine the severity of FG. FGSI: proposed by Laor in 1995, a score of >9 associated with a 75% probability of death, <9 associated with a 78% probability of survival.

LRNIC (Laboratory Risk indicator for necrotizing fasciitis) score: used to distinguish between cellulitis versus NSTI scores <6 more likely to be cellulitis not necrotizing fasciitis.

Radiographic work up:
KUB not reliable, shows gas in only 57% of cases
Ultrasound: may show thickened scrotal tissue w/ acoustic shadowing secondary to bacteria. Testicular blood supply is generally preserved
Testicular viability can be assessed with US

A scoring system for CT scans has been developed.

A score >6 points was 86.3% sensitive and 91.5% specific for the diagnosis of NSTI
(positive predictive value, 63.3%; negative predictive value, 85.5%)

Wound Management:
Dakin (diluted chlorine solution) vs Iodine wound dressing changes: Pts treated with Dakin solution 8.9 days vs 13 days of iodine patients.

Medihoney: healthy granulation tissue formed 9.62 +/- 4.5 days and for traditional dressing changes was 10.5 +/- 3.79 days. The hyperosmolar honey draws out edematous fluid and desiccates the wounds in addition to the production of high levels of H202 by enzymes in the honey.

Negative pressure wound therapy: 50-125mmHg negative pressure increasing blood supply encouraging migration of inflammatory cells. Accelerates formation of granulation tissue, removes exudates. NPWT increased length of stay however lowered mortality. NPWT patients required more.

Reconstruction should be delayed for at least 5-7 days from last debridement. STSG (0.012”-0.016”) from anterior or lateral thigh are preferred in the setting of FG as there is better take in contaminated regions. Moist nonadherent dressings should remain in place for 5 days.

- Scrotal defects with <60% skin loss can be closed primarily
- Unmeshed grafts are optimal for penile cosmesis and prevent potential contraction & curvature
- Perineal defects heal best through secondary intention. High shear stress in this region is prohibitive to skin grafts.

- Preservation of testicles can be achieved using thigh pouches, fasciocutaneous/musculocutaneous flaps.
- Thigh pouches can shorten hospital stays and reduce recovery time.
- For large penoscrotal defects, use of a gracilis flap with an internal pudendal perforator flap.

The numbers of management:
Average of 2.2 +/- 1.6 surgeries
10% will get ventilated
1.4% will get dialysis
15% will require a diverting colostomy
7% will need reconstructive surgery
Median stay of 8 days in hospital
30% will require home health at discharge

References:

pubmed.ncbi.nlm.nih.gov/26445600/
pubmed.ncbi.nlm.nih.gov/30182399/
pubmed.ncbi.nlm.nih.gov/28375805/
pubmed.ncbi.nlm.nih.gov/27172977/
pubmed.ncbi.nlm.nih.gov/31975540/
pubmed.ncbi.nlm.nih.gov/33126879/
pubmed.ncbi.nlm.nih.gov/21610394/
pubmed.ncbi.nlm.nih.gov/25742878/
pubmed.ncbi.nlm.nih.gov/32236663/

I hope you learned something interesting! Thank you for your time.