Percutaneous drainage for treatment of infected pancreatic pseudocysts. (Original Article).

Background: Infection of pancreatic pseudocysts is a potentially fatal complication that must be treated immediately. Despite numerous published reports about percutaneous treatment, the effectiveness of percutaneous catheter drainage (PCD) of infected pancreatic pseudocysts is still under discussion.

Methods: In this study, 30 patients (17 women) with 30 infected pancreatic pseudocysts were administered local anesthesia and underwent PCD performed with the use of a single-step trocar technique with computed tomographic guidance. The patients' ages varied from 27 to 74 years (mean age, 45 yr). The etiology was acute pancreatitis in 18 patients, chronic pancreatitis in 11 patients, and surgical trauma in 1 patient.

Results: No complications related to the procedure occurred in our series. The success rate was 96% (29 of 30 patients), with no recurrence during follow-up, which ranged from 2 to 58 months (mean follow-up, 27.2 mo). One patient had unsuccessful PCD and was subsequently treated surgically.

Conclusion: Our findings indicate that PCD is a safe and effective front-line treatment for patients with infected pancreatic pseudocysts.

Key Words: infected pancreatic pseudocyst, pancreatic pseudocyst, percutaneous catheter drainage

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Pancreatic pseudocysts are defined as localized collections of fluid within the pancreatic tissue or the peripancreatic spaces. Most pseudocysts occur as complications of acute pancreatitis, but they may also be associated with chronic pancreatitis or pancreatic trauma.' The maturation period of pancreatic pseudocysts is approximately 2 to 6 weeks, and during this time spontaneous resolution is most likely. Although almost one-third of pancreatic pseudocysts regress spontaneously, a significant number of those cysts that do not resolve must be treated to prevent potential complications, including infection, hemorrhage, and/or rupture. (2, 3) Because infectious complications are responsible for approximately 80% of the deaths associated with acute pancreatitis, (4) an infected pseudocyst should be treated immediately to avoid multiple organ failure and death as a result of from sepsis. In the past, surgical treatment was the only option available for the treatment of patients with infected pancreatic pseudocys ts; however, recent advances have made percutaneous catheter drainage (PCD) another treatment option. We describe our experience with PCD performed to treat infected pancreatic pseudocysts in 30 patients.

Patients and Methods

Between September 1996 and April 2001, a total of 30 patients (17 women) with infected pancreatic pseudocysts underwent PCD performed in the Department of Radiology of the Cerrahpasa Medical Faculty of Istanbul University. The patients' ages ranged from 27 to 74 years (mean age, 45 yr). Sixteen patients were thought to have noninfected pseudocysts but presented with symptoms suggestive of pancreatic cystic infection, such as abdominal pain and tenderness, elevated white blood cell count, fever, nausea, and vomiting. Other patients were admitted with acute abdominal pain and a history of acute or chronic pancreatitis. Infection of pseudocysts was definitively determined by Gram's stain and cultures of aspirate. The etiologies varied. Pseudocysts developed as a result of acute pancreatitis in 18 patients, chronic pancreatitis in 11 patients, and surgical trauma during cholecystectomy in 1 patient. The size of the pseudocysts ranged from 5 to 24 cm (mean size, 12.4 cm). The location of the cysts varied as well a nd included the tail of the pancreas (n = 15), the body of the pancreas (n = 9), and the head of the pancreas (n = 6). All PCD procedures were performed with the patient under local anesthesia and a single-step trocar technique with computed tomographic (CT) guidance. Two pigtail-tipped catheter sizes were used: 10-French (13 patients) and 12-French (17 patients) (UreSil L.P., Skokie, IL; Flexima, Boston Scientific, Watertown, MA; A.M.I. Technologies, Ltd., Hod Hasharon, Israel; Navarre, CR Bard, Inc., Cavington, GA, Nephro-soft, OptiMed Medizinische Instrumente GmbH, Ettlingen, Germany). A total of 32 catheters were used to drain the infected pseudocysts (two patients required two catheters). The direct insertion approach was used in 28 patients, and the transgastric approach was used in 2 patients. Each patient was administered systemic antibiotics throughout the PCD procedure. All patients were discharged from the hospital with catheters in place and returned for outpatient follow-up visits until the catheters were removed. Catheter irrigation with antiseptic solutions or saline was not performed. In this study, the criteria for catheter removal were 1) clinical improvement, 2) less than 10 ml/d catheter output, and 3) no CT evidence of pseudocysts.

Results

PCD was an effective treatment for 29 (96%) of the 30 patients with infected pseudocysts in our study. The only patient in whom the treatment was not successful had two catheters inserted; subsequently, this patient underwent successful surgical treatment. The length of time that catheters remained in place ranged from 11 to 71 days (mean, 26.5 d). The amount of drained fluid ranged from 90 to 2,210 ml (mean, 604 ml). Length of hospitalization ranged from 4 to 13 days (mean, 7.2 d). White blood cell count ranged from 7,300 to 24,000/[mm.sup.3] (mean, 16,200/[mm.sup.3]) before the PCD procedure. White blood cell count returned to normal as early as 2 days or as late as 11 days after the procedure (mean, 6.5 d). Serum amylase levels before PCD varied from 155 to 670 IU/L (mean, 212 IU/L). In all pancreatic pseudocysts, infection was confirmed by Gram's stain and positive results of aspirate culture tests. Patient follow-up began on the day after catheter removal and continued for 2 to 58 months (mean follow-up, 27.2 mo). Control CT scans were obtained every 6 months, and no recurrence was detected in any patient during the follow-up period. We encountered none of the complications sometimes associated with the procedure (eg, pneumothorax, catheter dislodgement, bleeding, pancreatic fistula). Figures 1 and 2 illustrate two cases in which the results were representative of those obtained in our study population as a whole.

Discussion

Pancreatic pseudocysts are a common complication of both acute and chronic pancreatitis. The cysts are known to affect 16 to 50% of patients with acute pancreatitis and 20 to 40% of patients with chronic pancreatitis. (5) Pancreatic duct disruption is the initial pathologic event that triggers pseudocyst formation. The leakage of amylase-rich pancreatic juice into the peripancreatic tissue results in the formation of a nonepithelial cystic collection. These extravasated pancreatic enzymes then form an encapsulated mass that is surrounded by fibrous and granulated tissue, (6) a process that can take anywhere from 2 to 6 weeks. During this period, spontaneous resolution of the developing cyst is most likely. (7) Pancreatic pseudocysts most commonly arise in the region anterior to the body and the tail of the pancreas and generally extend into the lesser sac. (8) The clinical presentation of pancreatic pseudocysts is persistent abdominal pain, with or without radiation to the back, and elevated serum amylase levels. The ultrasonographic appearance of a noninfected pancreatic pseudocyst is that of a well-defined, smooth-walled, anechoic structure with acoustic enhancement. If the cyst is infected or hemorrhaging, however, debris within the cyst may be evident on an ultrasonogram. The CT appearance of a pancreatic pseudocyst is that of a well-defined capsule containing a homogeneous collection of material of a density close to that of water. Infected pseudocysts display a heterogeneous capsular content with increased density. Gas bubbles also may be seen within the infected pseudocyst.

Secondary pancreatic infections include pancreatic necrosis, pancreatic abscess, and infected pancreatic pseudocyst. In recent years, these pancreatic diseases have been considered as independent clinical entities with different clinical courses and outcomes. (4) The clinical presentation of infected pancreatic pseudocysts is similar to that of noninfected cysts but also includes abdominal tenderness and fever. Because the CT appearance that suggests infection is not reliable in most cases, (9) the diagnosis of infected pancreatic pseudocysts also rests on three clinical parameters: fever, elevated white blood cell count, and a positive culture result obtained after testing drained cystic fluid. These three parameters are considered the primary factors in distinguishing an infected from a noninfected pancreatic pseudocyst.

The most common microorganisms cultured from the aspirates are enteric microorganisms, including Escherichia coli, Bacteroides species, Enterobacter species, Klebsiella species, and Streptococcus faecalis. In our study, 21(70%) of the 30 infections were polymicrobial, and the remainder (30%) were monomicrobial. These findings correspond with laboratory findings reported in other investigations. (4, 10)

Although almost one-third of pancreatic pseudocysts regress spontaneously, some (especially those larger than 6 cm) require treatment to prevent cystic infection, rupture, hemorrhage, and the resultant obstruction of the stomach, small bowel, colon, or bile ducts. Complications such as these have been reported in 24% of cases, with an associated mortality rate of 6%. (3, 11)

The clinical significance of infected pancreatic pseudocysts is their association with higher morbidity and mortality rates than noninfected pseudocysts. The results of a study by Fedorak et al (12) underline the importance of early recognition and urgent treatment of infected pancreatic pseudocysts. In their investigation of patients with infected pseudocysts, 26% of the study population had serious complications, which included abscess formation, pancreatic fistula, gastrointestinal hemorrhage, sepsis, and multiorgan failure. The mortality rate in this study population was 9%. (12)

For many years, surgery was the only treatment option for infected pancreatic pseudocysts. Other methods have since been developed, including PCD, endoscopic cystoenterostomy, and percutaneous cystogastrostomy. Another treatment option for pancreatic pseudocysts is expectant management, as Yeo et al (13) suggested. They showed that selected pseudocysts (ie, those smaller than 6 cm) can be managed with observation alone. Although PCD is being performed with increasing frequency in the management of pancreatic pseudocysts, there is no consensus that PCD is the definitive primary treatment. Heider et al (14) reported that, compared with surgery, PCD was associated with a higher overall failure rate, a higher mortality rate, and longer hospital stay in unselected patients. According to Criado et al, (15) PCD should not be considered the definitive form of treatment, because of its high failure and recurrence rates. On the basis of these findings, these investigators recommended surgery as the optimal treatment of pancreatic pseudocysts.

Although the mentioned reports cast a relatively negative light on PCD as a treatment option, significantly more reports have suggested the superiority of PCD over surgery or other treatment methods. Adams and Anderson (16) compared PCD with surgical internal drainage and found that the mortality rate was higher in surgically treated patients (7.1%) than in those who underwent PCD (0%). In a study by Lang et al, (17) PCD cured 11 of 14 infected pancreatic pseudocysts and was palliative in the remainder of them. In general, mortality rates for the surgical treatment of pancreatic infections (including infected pancreatic pseudocysts) range from 11 to 61%, (12) with frequent reoperations also reported (ie, in as many as 57% of the cases). (18) Several other investigators have also shown that the risk of PCD-related complications is far less than the risk of surgical complications. (3, 18, 19) In their series of 101 cases of infected and noninfected pancreatic pseudocysts treated with PCD, vanSonnenberg et al (2 0) reported a complication rate of 13%. These data as well as our own indicate that PCD is an effective primary treatment for patients with infected pancreatic pseudocysts. (4, 18, 20, 21)

Treating infected pancreatic pseudocysts with PCD has several advantages, especially compared with surgery. The reported complication and mortality rates associated with PCD are lower than those associated with surgical treatment, and older patients tolerate PCD far better than they tolerate surgery. Surgical treatment for infected pseudocysts requires general anesthesia, a factor that may be problematic for older patients, whereas PCD is not a major surgical procedure and therefore does not require general anesthesia. In addition, the potential failure of a PCD procedure does not eliminate the possibility of surgery; in fact, it may even facilitate surgery in complicated cases. (17) In such situations, the unsuccessful PCD procedure serves instead to stabilize the patient, thereby increasing the chances of a successful surgical procedure, as we experienced with one of our patients. PCD procedures also shorten the hospital stay, because patients discharged with a catheter in place do not need to remain in the hospital for as long as those who undergo a surgical procedure. Costs associated with the procedure (eg, equipment, length of hospital stay) are much lower than those associated with surgery, and PCD procedures also are much simpler to perform than surgery.

The percutaneous management of infected pancreatic pseudocysts requires that multidisciplinary workup be performed. Before planning a PCD procedure, the patient should be assessed by both a clinician and an interventional radiologist so that the patient can be directed to other treatment methods if PCD is contraindicated because of hemostatic disorders, another intra-abdominal surgical condition, ascites, or vital structures in the pathway to the pseudocyst. Therefore, good communication and cooperation between the radiologist, the gastroenterologist, and the surgeon are always essential to successfully perform PCD and manage complications.

Two catheter insertion techniques--Seldinger and trocar--are used in PCD procedures. The Seldinger technique involves an initial puncture of the cyst with a biopsy needle followed by the insertion of a guidewire through the needle. The needle is then removed, and a drainage catheter is placed within the cyst over the guidewire. The guidewire is then removed. In the trocar technique, the catheter is equipped with a stiff needle inside the lumen of the catheter, which allows for direct insertion of the catheter into the pseudocyst. In both procedures, the drainage catheter is sutured to the patient's skin. Because the trocar technique involves less manipulation and instrumentation and thus less risk of contamination, we prefer it to the Seldinger technique. This point is especially important in the management of infected pseudocysts, because the existing infection must be prevented from spreading to peripheral tissues and causing an abdominal abscess and/or sepsis. Although there are several approaches to pancr eatic pseudocysts, including the transgastric, transhepatic, transduodenal, arid transsplenic approaches, (20) the direct approach seems to be the least complicated and the most successful. We used the transgastric route for PCD in only two patients and the direct approach in the remaining cases.

Although the literature contains some controversial reports about percutaneous treatment of patients with pancreatic pseudocysts, this method continues to be used with increasing frequency. Our investigation and others indicate that PCD is safe and effective, with lower morbidity and mortality rates and shorter hospital stays being reported consistently. Successful PCD of an infected pancreatic pseudocyst requires close interaction and communication between the radiologist, the internist, and the surgeon during the entire disease course.

Accepted June 26, 2002.

References.

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(2.) Anderson MC, Adams DB. Pancreatic pseudocysts: When to drain, when to wait. Postgrad Med 1991;89:199-200, 203-206.

(3.) Torres WE, Evert MB, Baumgartner BR, Bernardino ME. Percutaneous aspiration and drainage of pancreatic pseudocysts. AJR Am J Roentgenol 1986;147:1007-1009.

(4.) Lumsden A, Bradley EL III. Secondary pancreatic infections. Surg Gynecol Obstet 1990;170:459-467.

(5.) Grace PA, Williamson RC. Modern management of pancreatic pseudocysts. Br J Surg 1993;80:573-581.

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(8.) Sutton D (ed). Textbook of Radiology and Imaging. New York, Churchill Livingstone, 1998, vol 2, ed 6, p 1055.

(9.) Federle MP, Jeffrey RB, Crass RA, Van Dalsem V. Computed tomography of pancreatic abscesses. AJR Am J Roentgenol 198l;136:879-882.

(10.) Bassi C, Vesentini S. Nifosi F, Girelli R, Falconi M, Elio A, et al. Pancreatic abscess and other pus-harboring collections related to pancreatitis: A review of 108 cases. World J Surg 1990;14:505-512.

(11.) Grosso M, Gandini G, Cassinis MC, Regge D, Righi D, Rossi P. Percutaneous treatment (including pseudocystogastrostomy) of 74 pancreatic pseudocysts. Radiology 1989;173:493-497.

(12.) Fedorak IJ, Ko TC, Djuricin G, McMahon M, Thompson K, Prinz RA. Secondary pancreatic infections: Are they distinct clinical entities? Surgery 1992;112:824-831.

(13.) Yeo CJ, Bastidas JA, Lynch-Nyhan A, Fishman EK, Zinner MJ, Cameron JL. The natural history of pancreatic pseudocysts documented by computed tomography. Surg Gynecol Obstet 1990;170:411-417.

(14.) Heider R, Meyer AA, Galanko JA, Behrns KE. Percutaneous drainage of pancreatic pseudocysts is associated with a higher failure rate than surgical treatment in unselected patients. Ann Surg 1999;229:781-789.

(15.) Criado E, De Stefano AA, Weiner TM, Jaques PF. Long term results of percutaneous catheter drainage of pancreatic pseudocysts. Surg Gynecol Obstet 1992;175:293-298.

(16.) Adams DB, Anderson MC. Percutaneous catheter drainage compared with internal drainage in the management of pancreatic pseudocyst. Ann Surg 1992;215:571-578.

(17.) Lang EK, Paolini RM, Pottmeyer A. The efficacy of palliative and definitive percutaneous versus surgical drainage of pancreatic abscesses and pseudocysts: A prospective study of 85 patients. South Med J 1991;84:55-64.

(18.) vanSonnenberg E, Wittich GR, Casola G, Stauffer AE, Polansky AD, Coons HG, et al. Complicated pancreatic inflammatory disease: Diagnostic and therapeutic role of interventional radiology. Radiology 1985;155:335-340.

(19.) Gerzof SG, Johnson WC, Robbins AH, Spechler SJ, Nabseth DC. Percutaneous drainage of infected pancreatic pseudocysts. Arch Surg 1984;119:888-893.

(20.) vanSonnenberg E, Wittich GR, Casola G, Brannigan TC, Karnel F, Stabile BE, et al. Percutaneous drainage of infected and noninfected pancreatic pseudocysts: Experience in 101 cases. Radiology 1989;170:757-761.

(21.) Pitchumoni CS, Agarwal N. Pancreatic pseudocysts: When and how should drainage be performed? Gastroenterol Clin North Ant 1999;28:615-639.

RELATED ARTICLE: Key Points

* Infected pancreatic pseudocysts cause greater morbidity and mortality than noninfected pseudocysts.

* An infected pseudocyst should be treated immediately to avoid multiple organ failure and death as a result of sepsis.

* Treating patients with infected pancreatic pseudocysts with percutaneous catheter drainage has several advantages, especially compared with surgery.

* The interventional radiologist should always keep in mind that successful percutaneous catheter drainage of an infected pancreatic pseudocyst requires close interaction with and communication between the radiologist, the internist, and the surgeon during the entire course of the disease.

* Our findings, as well as those of others, indicate that percutaneous catheter drainage of infected pancreatic pseudocysts is safe and effective and results in lower morbidity and mortality and shorter hospital stay.

From the Departments of Radiology and General Surgery, Cerrahpasa Medical Faculty, Istanbul University, Istanbul, Turkey.

Reprint requests to Murat Cantasdemir, MD, Department of Radiology, Istanbul University Cerrahpasa Medical Faculty, 34300 Kocamustafapasa, Istanbul, Turkey.

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