A Case of Severe Lumbar Necrotizing Soft Tissue Infection from an Ileal Pouch Fistula

Abstract

Background:

Necrotizing soft tissue infection (NSTI) is a rapidly progressive infection characterized by tissue necrosis, septic shock, and is associated with a high risk of death. Key aspects of successful treatment include early recognition and emergent surgical source control. Necrotizing soft tissue infection may occur from a range of etiologies but may also occur rarely from gastrointestinal routes. We report a case of severe lumbar NSTI arising from an ileal pouch fistula in a patient with inflammatory bowel disease. We report a case of a 62-year-old male with a history of ulcerative colitis and restorative proctocolectomy who presented with a severe NSTI of the lumbar region.

Methods:

Our operative approach focused on debridement of infected necrotic tissue and abscess drainage to achieve source control. We elected to forego a transabdominal approach during the initial operation given that source control but not source elimination was deemed the initial priority.

Results:

The patient subsequently underwent a diverting ileostomy and pouch salvage. After a prolonged hospital course, the patient recovered well.

Conclusions:

Fistulization from the gastrointestinal tract is a rare but potential source of NSTI. It is not necessary to address the fistula during the initial operation but should be done promptly after the patient stabilizes. Prompt surgical debridement of infected soft tissue as source control remains the cornerstone of the index operation.

Complications of restorative proctocolectomy (total abdominal colectomy with ileal pouch anal anastomosis) for ulcerative colitis (UC) are common and include inflammation, stricture, and fistula [1,2]. Pouch-related fistula can be highly morbid, often resulting in pouch excision and permanent ileostomy, although most are chronic processes and rarely fatal. Necrotizing soft tissue infections, however, are rapidly progressive and have a high mortality rate [3]. Necrotizing soft tissue infections (NSTIs) are rare and occur most often from traumatic injuries or intravenous injection of illicit drugs, but can also arise from ischemic, hematogenous, or gastrointestinal routes. To our knowledge there are no reports in the literature of an NSTI arising from a pouch-related fistula. We report here a case of severe lumbar NSTI arising from a pouch fistula in a patient with inflammatory bowel disease.

Case Report

A 62-year-old male presented to the emergency department with low back pain associated with erythema and blistering over his lumbar region. This was an exacerbation of a two-week history of lumbar pain, malaise, fatigue, and night sweats. He denied fevers, nausea, or change in bowel habits. His prior medical history was notable for UC for which he had undergone a colonic resection with restorative proctocolectomy 12 years previously.

On examination he was afebrile, tachycardic, normotensive, and his abdomen was non-tender. There was exquisite tenderness of his lower back from the level of T5 down through his buttocks extending bilaterally across his flanks, as well as induration, severe erythema, and palpable crepitus and hemorrhagic blistering. Laboratory investigations were notable for a leukocytosis (21,500), hyponatremia (129 mEq/L), acute kidney injury (creatinine = 1.6), and a bicarbonate of 21 mEq/L. A Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) score was calculated to be 9. Computed tomography scan of the abdomen and pelvis, ordered prior to surgical consultation, demonstrated extensive soft tissue inflammatory changes associated with intra-muscular abscesses in the posterior paraspinal soft tissues with air tracking along the subfascial planes involving the lumbar and pre-sacral regions, as well as bilateral gluteal muscles. There also appeared to be a fluid-filled fistulous connection from the pelvic bowel into the right external soft tissues (See Fig. 1.).

FIG. 1.

Computed tomography scan of the patient.

The patient was commenced on resuscitation and broad spectrum antibiotic agents including piperacillin/tazobactam, clindamycin, and vancomycin and was taken emergently to the operating room for debridement. Given the life-threatening nature of the NSTI, it was deemed most important to commence the approach from the back to achieve source control and drainage of the paraspinal abscesses. It was also elected to forego a transabdominal approach to the pouch fistula during the immediate operative intervention. Although it may have been necessary in an effort to attain source elimination [4], it was not essential to achieving source control at this immediate setting.

After unroofing the lumbar necrotic central lumbar soft tissue, a large volume of purulent material was drained. The myonecrosis and necrotic soft tissues tracked from bilateral buttocks to the mid-third of the scapulae. All necrotic material was excised. Attention was then focused on the epicenter, the central lumbar paraspinous area, where more myonecrosis was debrided down to the bony lumbar spine. Small bowel content was noted to extrude from this region. The incisions were packed and overlying dressings applied. The patient had a prolonged and complicated post-operative course. Post-operative laboratory investigations were most notable for a profound acidosis (pH 7.1), elevated lactic acid (12.6), and worsening kidney injury. Early in his intensive care unit (ICU) stay he suffered a cardiac arrest. After resuscitation he was noted to have developed a new left bundle branch block and an echocardiogram revealed apical and anterolateral hypokinesis. Coronary angiography did not demonstrate any stentable lesions and he was commenced on dual-agent anti-platelet therapy.

Over the next two days, the patient's hemodynamics, acidosis, and acute kidney injury improved. He was taken back to the operating room on post-operative day one for minor debridement (See Fig. 2). On post-operative day two, a pouch endoscopy, conducted at the bedside, confirmed the presence of multiple fistulae. Despite the risks of operative intervention in the setting of a recent myocardial infarction, the benefit of a diverting ileostomy was deemed most appropriate to attain source elimination, allow for healing, and prevent further infection. During laparotomy, a posterior mid-line pouch disruption was noted. A diverting loop ileostomy was created. The patient tolerated the procedure well.

FIG. 2.

Patient's wound.

Cultures confirmed a type I infection that grew Escherichia coli, α-hemolytic streptococcus, and yeast. Antibiotic agents were narrowed to piperacillin/tazobactam and fluconazole. Pelvic magnetic resonance imaging (MRI) demonstrated erosive changes of the sacrum and evidence of osteomyelitis. Antimicrobial agents were prescribed for six weeks. With appropriate care his wound granulated and ultimately was covered with an autograft. After discharge his wounds have healed well and he has not required or undergone pouch excision.

Discussion

Necrotizing soft tissue infections are rare, rapidly destructive surgical infections of the soft tissue compartments anywhere in the body, often involving the fascial and/or muscle layers [5]. They present commonly with acute onset progressively worsening pain, as the deep tissues undergo ischemic and necrotic changes with infection tracking along the tissue planes. Necrotizing soft tissue infection is accompanied invariably by subcutaneous edema, bullae formation and petechial hemorrhage, fluid from liquefaction, and a rapidly progressive cellulitis. The disease advances disturbingly over minutes to hours, frequently resulting in substantial tissue loss, septic shock, and death. In addition to its trophic tendencies and layers of involvement, NSTI may also be classified based on microbial etiology [3]. The most prevalent is type I infection characterized by polymicrobial infection of both aerobes and anaerobes. Type II NSTI involves monomicrobial group A Streptococcus (GAS) infections, previously referred to as acute hemolytic streptococcal gangrene. Type III NSTI involves infection with Clostridial species, especially Clostridium perferingens, and are most likely associated with gas formation and crepitus upon examination. The water born Vibrio or Aeromonas species infections are sometimes included as type III NSTIs.

Fistulae are abnormal tracts from viscera to the skin, atmosphere, or other viscera and can develop from a number of etiologies such as infection, neoplasm, or inflammation. Fistulae are a hallmarks of Crohn disease [6], an inflammatory bowel disease affecting the entire gastrointestinal tract. These present commonly in the peri-anal region accompanied by mild inflammation and at times require multiple drainage procedures and local wound care. Although Crohn disease is a systemic disease, the fistula rarely leads to systemic symptoms or sepsis. Ulcerative colitis, the other main condition constituting inflammatory bowel disease, is characterized by continuous mucosal inflammation of the rectum and colon, and is not believed to be associated with fistulae formation. Whereas treatment for UC is largely medical, some patients require removal of their colon and rectum for refractory disease that is ultimately curative [7]. A number of options exist for preserving continent function and avoiding a permanent ileostomy in these patients, with one of the most frequently performed reconstructions being the ileal pouch with anal anastomosis.

Not infrequently, patients originally diagnosed with ulcerative or indeterminate colitis and having undergone restorative proctocolectomy later develop fistula from their ileal pouch to the skin or other viscera. This may reveal either a missed initial diagnosis versus a new diagnosis of Crohn disease. However, a recent shift in our understanding now leads to a belief that inflammatory bowel disease is indeed a continuum or spectrum of inflammatory disease rather than two discrete entities divided into Crohn disease versus UC [7]. Fistula formation from ileal pouches in patients with UC have been reported, most frequently fistulizing from the pouch to the peri-anal area or vagina. The predominance of late septic pouch-related events present as pelvic sepsis or as intra-abdominal sepsis from a leak, most often related to a fistula in patients without an ileostomy [8]. To our understanding, this is the first report of a fistula arising from an ileal pouch for UC leading to an NSTI.

Fistula development has been reported to arise from necrotizing processes such as pancreatitis or necrotizing enterocolitis or from infected traumatic injuries. However a necrotizing disease initiated by an enteric fistula is a rare event. There have been increasing numbers of reports of NSTIs arising from appendiceal or diverticular infections fistulizing to the retroperitoneum, perineum, or truncal wall soft tissues. Because of their acuity and rapid progression, NSTIs require early recognition and emergent surgical intervention to minimize the septic and physiologic burden, control the septic source, prevent further tissue loss, and ultimately prevent mortality. Source control does not mandate source elimination during the sentinel operation. In a case such as this, it is critical to address the septic burden first [9].

We therefore chose to address the debridement of infected, necrotic soft tissue as the paramount concern. Indeed in cases of NSTI, any additional operative intervention may induce an excess burden upon an already fragile physiology. It is critical for the operative team to realize the emergent versus urgent procedures that need to be undertaken. The strategy of addressing the fistula in a delayed second operation with fecal diversion after stabilization of the septic physiology of an NSTI is to be advocated.

Necrotizing soft tissue infections are a rapidly progressive, highly morbid, and often fatal infectious process. Emergent diagnosis and operative intervention, with a clear understanding of source control irrespective of the initiating event remains at the core of the care of NSTIs.

Footnotes

Author Disclosure Statement

No competing financial interests exist.

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