A 27-Year-Old Man with Chronic Traumatic Pancreatic Fistula Managed with Percutaneous Microwave Ablation

Introduction

Pancreatic fistulas remain among the most feared post-traumatic pancreatic complications, with a high risk of dire clinical consequences such as abscess formations, hemorrhages and sepsis, which often go unrecognized in the acute setting [1,2]. In severe cases, widespread intra-abdominal inflammation and infection can lead to sepsis and increased mortality of up to 20% of patients, making it a serious medical emergency [3].

A fistula is an abnormal connection between 2 epithelial surfaces, which may be external (cutaneous) or internal (to viscera or spaces) [4]. In cases of pancreatic injury, contents of the pancreatic ductal system can leak into its surroundings, eroding tissue and leading to inflammation. Although the pathophysiology is poorly understood, it is theorized that persistent leakage can lead to chronic inflammation and granulation, as well as forming a tract which epithelializes, further solidifying the tract [4,5]. Pancreatic fistulas are most often iatrogenic, presenting as postoperative pancreatic fistulas [2]. Non-iatrogenic causes such as abdominal trauma and pancreatitis are less common than postoperative pancreatic fistula, with blunt trauma-caused pancreatic fistula being especially diagnostically challenging, leading to higher rates of morbidity and mortality [1].

The best diagnostic indicator for pancreatic fistula and pancreatic ductal injuries is amylase detection in peritoneal drainage fluid [2]. Computed tomography (CT), magnetic resonance cholangiopancreatography (MRCP) and endoscopic retrograde cholangiopancreatography (ERCP) have also been consistently shown to be useful in diagnosing pancreatic ductal disruptions [6].

Management initially consists of a conservative approach if ductal injury is insignificant, as total parenteral nutrition (TPN) and drainage may lead to complete resolution in less-severe cases [2,7]. In select cases, ERCP allows for multiple endoscopic techniques like transpapillary stenting and redirecting of the pancreatic secretions from the abnormal connections back to the duodenum, effectively closing the leakage. In more severe cases, abdominal and pancreatic intervention may be required [7,8].

Microwave ablation is an image-guided thermal ablation technique commonly used for surgically complex malignancies [9]. Thermal ablation relies on temperature extremes to resect or destroy target tissues. It has become increasingly used in clinical settings, especially in oncology, due to its precise yet minimally invasive nature. Other types of thermal ablation include radiofrequency ablation (RFA), laser interstitial thermal therapy, and cryoablation [9,10]. Percutaneous microwave ablation systems are generally composed of 3 components: a microwave generator, which generates the electromagnetic energy; a distribution system, which carries the generated energy; and a percutaneous antenna, which transfers the energy from the previous components to the target tissue (commonly 915 MHz or 2.45 GHz), to produce coagulative necrosis. Under CT or ultrasound guidance, an 11- to 18-gauge antenna is positioned in the target and energy is applied for several minutes to achieve tissue or tract obliteration. Heat is generated through a process that sends electromagnetic radiation to polar molecules like water, which experience internal friction as they try to realign themselves in the rapidly alternating electromagnetic field. This constant reorientation of the molecules, termed dielectric hysteresis, is the basis by which friction and therefore heat is generated. Since human tissue contains a lot of water and other polar molecules, this makes it highly conductive and thus easily burnt by microwave radiation [11,12].

Although commonly used for hepatic, renal, and pulmonary malignancies, its application to pancreatic pathologies is rare, and even more so for pancreatic fistulas. A recent case by Sallemi et al described the successful closure of a post-nephrectomy urinary fistula using microwave ablation in a 56-year-old man with a horseshoe kidney [13]. Another report by Barrera et al described CT-guided transhepatic microwave ablation of a gallbladder remnant to close a cholecystocutaneous fistula after partial cholecystectomy in a 54-year-old woman. Following the procedure, she was asymptomatic at 2.5 years follow-up [14]. This suggests the feasibility of ablative tract occlusion techniques for selected non-neoplastic fistulas. However, we could not find any previous reports of the use of microwave ablation for pancreatic fistulas in the literature.

Herein we aim to present the complicated case of a 27-year-old male patient with a chronic traumatic pancreatic fistula that was successfully managed with percutaneous microwave ablation.

Case Report

A 27-year-old man from Pakistan with no remarkable medical history was involved in a motor vehicle accident, becoming trapped between the seat and the steering wheel for over an hour. He was taken to the emergency department (ED) of an outside facility in an ambulance where an emergency exploratory laparotomy was performed to control the liver bleeding, which overlooked a pancreatic contusion with main duct injury. During the 16 days he spent at that hospital, he underwent 3 laparotomies with angioembolization of the celiac trunk to control bleeding. He was started on octreotide and allowed oral nutrition. Three days later he complained of severe abdominal pain and bloating. The drain showed high amylase output, and CT showed a large collection behind the stomach which was drained with a pigtail catheter. The patient became stable and was discharged with the pigtail drain in situ.

He presented to a different hospital a week later complaining of fever and abdominal pain. Abdominal and pelvic CT showed a large lobulated cystic collection in the right lobe of the liver as well as mild compression on the left side of the abdomen which was suspected to be an abscess. The chest X-ray revealed a bilateral pleural effusion, particularly on the left side. These signs, in addition to the presence of amylase in the upper abdominal drain, provided evidence of a persistent traumatic pancreatic fistula, which was the underlying reason for repeated collection and sepsis. This finding prompted immediate referral to our specialized care facility at Burjeel Hospital. On admission to the intensive care unit (ICU), the physical exam showed abdominal guarding, tenderness, and mild distention. Chest examination showed decreased air entry. Laboratory investigation showed signs of infection and markedly increased liver function tests. Drain results showed high levels of lipase and amylase. Serum pancreatic enzymes were increased as well. MRCP identified an intrahepatic cyst, and a thick-walled collection in the lesser sac was seen communicating with the mid-portion of the main pancreatic duct. Two ERCP attempts were made to see and potentially manage the source of leaking in the pancreas, both of which were unsuccessful as the main pancreatic duct had been transected.

The patient spent 2 weeks in the ICU, after which a conservative attempt at curing the disease was made with insertion of a new drain and placing the patient on TPN for a month. This was deemed futile, as the patient did not improve, and the pancreatitis was further complicated by a central catheter fungal infection, leading to sepsis and bilateral pleural effusion with respiratory insufficiency. A bedside multidisciplinary team discussion concluded that conservative management would have no chance at success unless the underlying issue – the transected pancreatic leak source – was not resolved. Hence, a decision was made to perform a further laparotomy to re-explore the pancreas and the abdomen before the patient could be extubated.

The laparotomy was performed around 2 months post-accident, during which large amounts of infected fluid and necrosis were removed and washed. The stomach, liver, transverse colon, and pancreas were embedded together “en bloc” due to severe inflammation and sepsis. The transverse colon was especially adherent to the spleen and to the tail of the pancreas. Thus, a decision was made to do a distal pancreatectomy, splenectomy, and transverse colon resection as it would allow for proper debridement and better access to the affected pancreas (Figure 1). The surgery ended with formation of a temporary ileostomy and drains placed in the 4 abdominal quadrants.

The patient experienced a postoperative episode of sepsis and developed ischemic gangrenous cholecystitis with perforation, and he was taken for relaparotomy and cholecystectomy. Post-surgery, the patient was treated conservatively with TPN and octreotide for 2 months. However, he showed no improvement and developed additional pancreatogenic collections and sepsis.

At around 4.5 months after the patient’s accident, a multidisciplinary team meeting was held in view of the patient’s lack of clinical improvement, during which a decision was made to conduct percutaneous microwave ablation on the remaining 2 cm of the ruptured pancreatic neck-body, as a last resort at treating the fistula. The procedure was done under general anesthesia. An 18-gauge microwave needle was inserted under CT-guidance and positioned at the remaining 2 cm of the pancreatic body-neck junction. After confirming the correct position of the needle, ablation was performed for 5 minutes. The end goal of the procedure was to ablate the remnant neck-body of the distal part of the main pancreatic duct that was causing the fistula, which was achieved successfully. We have included pre-operative (Figure 2), intra-operative (Figure 3), and postoperative (Figure 4) CT images.

The patient suffered transient neuropraxia during the procedure, which was entirely reversible. Two weeks following the microwave ablation treatment, a second try at conservative management with TPN, octreotide, and fat-free diet showed no secretions in the drain for 2 days and thus the drain was removed. The patient had no fevers and no pain. After the operation, he was tolerating food well and his ileostomy was functioning properly.

After more than 5 months of hospitalization, the patient was released in good clinical condition and traveled back to his home country. The ileostomy was reversed 1 month after discharge. No changes to his lifestyle or diet were reported and vaccinations were administered on schedule. We have provided a summary timeline of the events in Figure 5.

Discussion

This case demonstrates that percutaneous microwave ablation can achieve definitive closure of a chronic traumatic pancreatic fistula when mainstream management guidelines like conservative therapy, drainage, and ERCP fail. This case serves to illustrate a minimally invasive alternative in anatomically hostile and sepsis-prone settings. It also underlines the importance of early consideration and diagnosis of pancreatic fistulas in abdominal trauma.

Pancreatic injuries from trauma are generally uncommon. A United States analysis of the National Trauma Bank reported a rate of 0.3%, with an overall mortality of 21.2% and morbidity of 53%, making early diagnosis and treatment critical [15]. Thus, early diagnosis and management of pancreatic fistula is critical for better patient outcomes [16]. Early intervention with ERCP is recommended to reduce complications and mortality, especially in suspected pancreatic ductal injuries [8]. In the present case, failure to perform ERCP immediately when amylase was detected in the drain may have led to the development of the subsequent morbidities and complications.

Diagnosis of pancreatic fistula was based on the finding of increased amylase and lipase concentration in the drain fluid, which is the most important diagnostic criterion according to the latest grading by the International Study Group of Pancreatic Surgery (ISGPS) in 2016 [2].

Our patient’s initial presentation mainly consisted of abdominal pain, fever, and pleural effusion. Our patient had a long course with recurrent sepsis and intra-abdominal collections. Placing this in the context of the literature, in the cholecystocutaneous fistula case, the patient presented around 4 months after a previous partial cholecystectomy with gradually evolving abdominal wall erythema [14]. In the urinary fistula case, the patient presented much more acutely, within 12 days post-nephrectomy with abdominal pain [13]. In both previously mentioned case reports, the fistulas were diagnosed with CT, since the fistulas in these reports were non-pancreatic [13,14]. In our case, CT was important to identify complications of the fistula; however, the fistula itself was confirmed by amylase presence in the drain and via MRCP to visualize exact anatomical location.

In terms of the patient’s management, TPN is used in most cases as the first line treatment for pancreatic fistula to reduce pancreatic secretions [2,7]. The use of octreotide remains controversial, with many studies showing no clear therapeutic benefit [17]. A very serious aspect of the patient’s clinical course was the recurrence of Candida sepsis. This type of sepsis most commonly occurs with prolonged ICU stays, patients who are immunocompromised or on broad-spectrum antibiotics, and in patients with indwelling devices like the central venous catheter. It is also seen in postoperative patients, especially after procedures relating to the gastrointestinal tract [18]. It was the recurrence of sepsis and the serious risk it presented to the patient, as well as the repeated failure of mainstream treatment that eventually led the multidisciplinary team to proceed with microwave ablation.

This is a novel instance of microwave ablation being used clinically for pancreatic fistulas. So far, the use of microwave ablation has been mostly studied for unresectable liver, lung, and renal cancers [19]. Ablation may be preferred over traditional operations in cases in which the patient is unsuitable for surgery or the tumor is in a difficult-to-reach location, or to reduce recovery time. It has also been shown to reduce postoperative occurrences [20]. Its use in pancreatic tumors is less documented, and even less so for non-neoplastic pancreatic conditions. There was an experimental study on porcine models which looked at the efficacy of RFA compared with glue occlusion in closing pancreatic stumps and reducing pancreatic fistulas. It concluded that RFA was more effective [21]. Paradoxically, previous clinical reports have shown microwave ablation itself to have caused fistulas [22,23]. Procedurally, the ablation was performed in a manner like that in the 2 cases mentioned previously. The Barrera et al case report used hydrodissection to protect surrounding structures [14]. In the urinary fistula by Sallemi et al, they used an ultrasound-guided catheter which has the benefit of minimizing radiation on both the patient and the medical team [13]. In all 3 cases, image-guided percutaneous microwave ablation provided definitive source control of pathologically leaking tissue. In our case the patient suffered more complications compared with the other cases, likely due to the difference in etiology, ours being traumatic rather than iatrogenic. Microwave ablation was also a last resort salvage decision, rather than an earlier definitive solution.

In our case the patient suffered neuropraxia after the ablation, which is not a common adverse effect of the treatment, but a possible explanation could be thermal damage from the ablation exerted to nearby neural plexuses [24]. For this reason, microwave ablation poses a challenge to doctors and requires precision and expertise. In the cholecystocutaneous case the patient developed a methicillin-resistant Staphylococcus aureus (MRSA) bacteremia for which she was successfully treated and was uncomplicated at 2.5 years [14]. No complications were reported in the urinary fistula case [13].

In the current step-up paradigm, endoscopic therapy remains the reference standard for ductal injuries, ERCP achieves 89% pooled clinical success with low mortality. Therefore, we recommend that it stays the first line management of moderate to severe pancreatic fistulas [8]. Nevertheless, in patients for whom ERCP is not feasible or fails, our case highlights a potential role for targeted microwave ablation to achieve thermal occlusion of the leak. Microwave ablation’s volumetric, high-temperature heating may offer decisive local control compared with adhesive embolization or prolonged catheter drainage, which may minimize inflammation and risk of therapeutic failure. Given the moderate complication rates of pancreatic pseudocysts, fistulas, and obstructive jaundice reported for pancreatic microwave ablation in oncologic series, rigorous selection and protective techniques are crucial [23]. Prospective comparative data are needed to define where microwave ablation belongs relative to ERCP-based strategies and percutaneous duct interventions.

Overall, all 3 case reports mentioned in our report used image-guided percutaneous microwave ablation to shut down an unusual and persistent source of leakage when standard treatments were not viable. Each demonstrated a rapid cessation of leakage and durable control.

Conclusions

Percutaneous microwave ablation achieved definitive closure of a chronic traumatic pancreatic fistula in a 27-year-old man after failure of conservative, endoscopic, and surgical strategies. This case highlights a novel application of microwave ablation as a feasible salvage option for refractory pancreatic fistulas and underscores the importance of early consideration and diagnosis of pancreatic fistula following abdominal trauma.