Correspondence *Box 43, Addenbrooke's Hospital, Hills Road, Cambridge CB2 2QQ, UK

Email tevita.aho@addenbrookes.nhs.uk

The case

A 59-year-old liver-transplant recipient presented with a 4-day history of scrotal pain and swelling that had progressed despite antibiotics prescribed earlier for a small infected scrotal skin lesion. Over the preceding 24 hours two foul-smelling, purulent, discolored areas appeared on the penis and scrotum. There was no history of urinary or bowel symptoms. He had received an orthotopic liver transplant 8 years previously for alcoholic liver disease in association with Hepatitis C infection. Comorbidity included immunosuppression by rapamycin, type 1 (insulin-dependent) diabetes mellitus, and poor nutrition.

On physical examination there was an overwhelmingly fetid odor. The patient appeared unwell and was dehydrated. His body temperature was 37.7°C, his heart rate was 125 beats/ min, his blood pressure was 90/60 mmHg, and his oxygen saturation was 92% on air. His abdomen was soft and nontender. There were areas of purplish and black skin discoloration leaking dishwater-like fluid on the penile shaft and anterior scrotum (Figures 1 and 2). The scrotal wall was edematous and exquisitely tender with palpable CREPITUS. The penis was tender and mildly swollen.

Figure 1 Photograph of patient's scrotum showing scrotal wall edema and skin discoloration.

 

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Figure 2 Photograph of patient's penis and scrotum showing almost circumferential distal penile skin involvement.

 

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Resuscitation with normal saline and broad-spectrum antibiotics (cefotaxime and metronidazole) was commenced immediately. Consent for radical DEBRIDEMENT, as well as possible colostomy, suprapubic catheter insertion and orchidectomy was obtained. Baseline blood results included a urea level of 30.2 mM (normal range 0–7.5 mM), a creatinine level of 266 M (35–125 M), a sodium level of 133 mM (135–145 mM), a potassium level of 5.1 mM (3.4–5.0 mM), an alkaline phosphatase level of 218 U/l (30–135 U/l), a C-reactive protein level >250 mg/l (0–6 mg/l), a white blood cell count of 12.3 10⁹/l (4–11 10⁹/l), and a glucose level of 26.2 mM.

Emergency examination under anesthesia (EUA) revealed crepitus involving the penis, scrotum and urogenital triangle. Digital rectal examination was unremarkable. Gangrenous subcutaneous tissue extended from the umbilicus to the perineal body. The entire scrotal wall and the penile shaft were affected; however, both testes with surrounding tunica vaginalis and the anal triangle were spared. All obviously necrotic tissue was debrided (Figure 3). Although the viability of the bulbar urethra and glans penis were questionable, these structures were not excised (Figure 4). The wound was packed and the patient transferred to the intensive care unit where his condition improved. No inotropes were required. Tissue cultures grew Streptococcus milleri and anaerobes. Blood cultures were negative. Histology revealed extensive acute inflammatory cells with foci of necrosis and acute vasculitis of arteries and veins with thrombus formation in both.

Figure 3 Appearance of patient's pubic region after initial debridement, with scrotum and suprapubic fat pad excised, testes preserved within tunica vaginalis, and penile skin and subcutaneous tissue debrided.

 

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Figure 4 Photograph of patient's pubic region after initial debridement, with testes displaced to show the extent of the perineal wound.

 

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At EUA 12 h later there had been no extension of the FASCIITIS. Plastic surgical involvement began with examination of the wound and advice on the timing and options for wound coverage and reconstruction. The wound was repacked. In view of renal-impairment and tissue-culture results, antibiotics were changed to reduced-dose meropenem.

At EUA 3 days after admission the glans penis appeared unlikely to survive but the fasciitis appeared to have been eradicated. At EUA 6 days after admission, after clearance of infection was confirmed by repeat swabs, the plastic surgeon approximated the testes within their tunics in the midline and covered them and the penile shaft with meshed split-skin grafts. The edges of the perineal and suprapubic wounds were approximated primarily.

At EUA 9 days after admission, the split-skin grafts were healthy but urethroscopy revealed full-thickness necrosis of the bulbar urethra. A PERINEAL URETHROSTOMY was fashioned and a suprapubic catheter placed.

A clearly demarcated region of dry GANGRENE involving the glans penis and distal shaft gradually evolved and PARTIAL PENECTOMY was performed 26 days after admission. Phallic reconstruction was not performed at this stage because the patient's condition was not yet optimal for such surgery. Split-skin grafting of a few remaining skin defects was performed 34 days after admission.

After overcoming complications that included pneumonia, poorly controlled diabetes, poor nutrition, and depression, the patient was discharged 72 days after admission, with phallic and possible urethral reconstruction planned within 6 months.

Discussion of diagnosis

Fournier's gangrene is defined as a synergistic, polymicrobial, necrotizing fasciitis of the perineum, scrotum and penis characterized by obliterative endarteritis, and resulting in gangrene of the subcutaneous tissue and overlying skin.¹ Whereas cellulitis is a skin infection involving cutaneous layers only as deep as the subcutaneous fat, Fournier's gangrene involves deep fascia.

An identifiable source of infection is reported in more than 75% of cases. In general, sepsis can arise from the colorectal region (13–50%), the urinary tract (17–87%), or, less commonly, the local skin, as in our patient.^{1, 2} The most common colorectal sources include perirectal, perianal and ischiorectal abscesses, rectal instrumentation, and colonic perforation. Urethral strictures with urinary extravasation, balanitis and urethral instrumentation are the most common urologic causes. Skin sources include superinfection of varicella pustules and infected insect bites.¹

Many patients have a comorbid condition resulting in immunosuppression, such as diabetes mellitus, transplant or chemotherapy, alcoholism, HIV/AIDS, prolonged hospital stay, malignancy, malnutrition and intravenous drug abuse. Up to 70% of patients with Fournier's gangrene are diabetic,³ and proposed mechanisms for this association include small-vessel disease that predisposes to tissue ischemia, defective phagocytosis that encourages bacterial spread, and increased incidence of urinary tract infections (although there is no association between urinary tract infections and Fournier's gangrene in the nondiabetic population).⁴ Whether diabetes affects outcome remains controversial.^{5, 6} Fournier's gangrene can affect all age groups and has been reported in both sexes.² The incidence of the disease is increasing, possibly in part because of an increasingly immunocompromised population, and increased reporting.⁷

Although presentation is variable, patients almost always present with pain and swelling of the affected areas.³ As the disease progresses, certain classical signs tend to develop such as dishwater-like discharge, a fetid odor, and skin necrosis. Crepitus is present in up to 60% of patients and is pathognomonic of Fournier's gangrene.²

In advanced cases such as this, diagnosis is clinical. In cases presenting prior to the development of typical symptoms and signs, ultrasound can confirm the diagnosis by showing gas within the scrotal wall and by excluding other causes of acute scrotum.⁸ CT and MRI can be useful in diagnosis and in demonstrating the extent of disease and presence of abscesses prior to EUA and debridement.^{9, 10}

Treatment and management

The four main principles of management of Fournier's gangrene are resuscitation, antibiotics, debridement, and, when necessary, reconstruction.

Resuscitation and correction of electrolyte disturbances should be followed by empiric broad-spectrum antibiotics that cover Gram-positive, Gram-negative and anaerobic bacteria. Polymicrobial culture of aerobic and anaerobic commensal organisms is the norm. Many have been described, including Clostridium, Klebsiella, Streptococcus, Corynebacterium, Staphylococcus, and Bacteroides species, as well as coliform bacteria.²

Urgent surgical debridement remains the cornerstone of treatment. The patient and the surgical team must be prepared for potentially major surgery. If adequate preoperative imaging has not been obtained prior to initial debridement, careful EUA is necessary to determine the extent of disease and to identify any underlying colorectal or urogenital pathology. The testes are rarely affected due to the abdominal source of their blood supply. If they are involved, intra-abdominal pathology should be suspected. Likewise, if the patient's condition deteriorates despite apparently adequate perineal debridement, an occult source of infection should be considered. Fecal and urinary diversion might be necessary to avoid wound contamination or to facilitate the treatment of underlying pathology, or both. There is no consensus on indications for diversion and each case should be considered individually. In our case, a suprapubic catheter was placed when it became clear that the bulbar urethra was nonviable. It is unlikely that a single debridement will be adequate; serial debridements are usually required.

A Fournier's gangrene severity index score based on clinical and laboratory parameters has been devised by Laor et al. to predict prognosis, although it has little application to the management of individual patients.¹¹ With this index, any deviation from homeostasis is associated with a worse prognosis.

Many surgeons advocate the use of hyperbaric oxygen therapy which can inhibit and kill anaerobes, reduce systemic toxicity, limit necrosis and enhance demarcation of gangrene.² Although there is a strong rationale for its use, it remains controversial as some evidence suggests it might not improve morbidity or mortality.¹²

With a mortality rate of up to 38%, the primary objective in the management of this often rapidly progressive condition is to limit and eradicate sepsis.³ Once this is achieved and the patient is well enough, the focus shifts to reconstruction if necessary. In our case the plastic surgical team provided an early physiologic skin graft 'dressing', and, later, definitive skin grafting. They also played an important role in counseling the patient with regard to the options for penile reconstruction which depend on what tissues are missing. If only skin and soft tissue is lost but the corpora cavernosa remain, a skin graft (preferably full thickness) is adequate. If penile length is required, various techniques, including gracilis or local flaps, have been described. If most of the phallus is lost, such as in our patient, an autologous reconstruction with microvascular tissue transfer and urethral reconstruction is the treatment of choice.^{13, 14} The radial forearm is the most commonly used flap. Sensation can be restored by coapting the pudendal nerves to the sensory nerve of the flap. An artificial erectile device can be inserted dorsally.¹⁵

A multidisciplinary approach, such as that involving urology, plastic surgery, anesthetics, intensive care, transplant, diabetes and nutrition in our case, is crucial in obtaining a good overall outcome.

Conclusion

Fournier's gangrene is a urologic emergency associated with high morbidity and mortality. The principles of management are immediate resuscitation, early broad-spectrum antibiotics, urgent surgical debridement (usually followed by serial EUAs), and when necessary, reconstruction once sepsis has been eradicated and fitness permits. Imaging can be useful in diagnosis and planning the extent of debridement, and hyperbaric oxygen therapy can be beneficial; however, neither should unnecessarily delay debridement in advanced cases. High quality care depends on a well coordinated multidisciplinary approach.

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Subject areas under which this article appears: Infections, inflammation and prostatitis