PANCREATIC PSEUDOCYSTS

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PANCREATIC PSEUDOCYSTS When and How Should Drainage Be Performed? C. S. Pitchumoni, MD, FRCP(C), MPH, and N. Agarwal, MD, FRCS(C), MPH

Single or multiple fluid collections giving the appearance of cysts on pancreatic imaging within or in the anatomic neighborhood of the pancreas are often seen during or after an episode of acute pancreatitis. The frequency with which cystic lesions are seen today with computed tomography (CT) scans performed in the evaluation of patients with pancreatitis or abdominal pain is many times that noted in the pre-CT scan ultrasound era, when only cysts big enough to cause morphologic abnormalities in adjacent viscera were detected by barium The number of new cystic collections found currently with sensitive radiologic studies and elucidation of their natural histories have raised the question of which of these need treatment. Advances in technology have considerably increased the therapeutic options. Surgical management, the timetested standard, has been challenged by interventional radiologists and endoscopists. This raises the second question as to how drainage should be performed. DEFINITION

Pancreatic pseudocyst, the most common cystic lesion of the pancreas, by definition is a localized collection of fluid rich in amylase From the Departments of Medicine (CSP), Community and Preventive Medicine (CSP), and Surgery (NA), New York Medical College, Valhalla; and the Department of Medicine (CSP) and the Surgical Intensive Care Unit (NA), Our Lady of Mercy Medical Center, Bronx, New York

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within or adjacent to the pancreas enclosed by a nonepithelialized wall occurring as a result of acute or chronic pancreatitis, pancreatic trauma, or pancreatic duct obstr~ction.'~ The extravasated pancreatic secretion evokes an inflammatory response resulting in a cyst wall composed of fibrous and granulation tissue over several weeks after its The lack of an epithelial lining in the cyst wall is characteristic. The cysts are round or ovoid in shape as demonstrated by CT or abdominal ultrasound. Pseudocysts are most commonly located adjacent to the pancreas in the lesser sac but have been reported to extend into the neck,sO media~tinum,4~ pelvis, and scrotum.69 The reported incidence of pseudocyst is l.6YO3Oto 69?'0.~~This wide variation in incidence is primarily related to the method of diagnosis. Earlier studies, based on upper gastrointestinal series, reported an extremely low incidence (1% to 3%) of pseudocyst formation.86Since 1970, the application of ultrasound and CT has led to more frequent discovery of fluid collections associated with pan~reatitis.~~ The term pseudocyst has been better defined to exclude other forms of evanescent fluid collections often seen in imaging ~tudies.'~ Notable among them are acute fluid collections, which occur in more than 50% of patients with moderate-to-severe acute pancreatitis. Acute fluid collections are not to be confused with pseudocysts because more than 50% of them regress spontaneously. They are usually located in or near the pancreas and lack a clear wall of granulation tissue. They represent a serous or exudative reaction to pancreatic injury and inflammation and do not have a communication with pancreatic duct. Therefore, they do not contain high concentrations of pancreatic enzymes, and the fluid composition is similar to that of plasma. Imaging studies indicate that they lack a well-defined wall, they are irregular in shape, and there is an indistinct interface between the fluid and adjacent organs (Fig. 1).

Figure 1. Acute fluid collections in the peripancreatic area. Note poorly defined wall and irregular shape.

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Table 1. FLUID COLLECTIONS WITH’Y OR ADJACENT TO THE PANCREATIC AREA IN PANCREATITIS Acute Fluid Collections

In moderate-to-severe pancreatitis

Nearly 65% spontaneous resolution Lack a well-defined wall Irregular shape May be multiple No communication with pancreatic duct May go on to pseudocyst

Pseudocysts

As a result of pancreatitis, trauma, or ductal obstruction Localized collection of fluid Well-defined cyst wall; no epithelial lining Rounded or oval in imaging studies Location adjacent to the pancreas in the lesser sac Communication often with the duct

Spontaneous resolution in 30%

Fluid collections that occur closer to the onset of acute pancreatitis in general have a greater chance of resolving and do not need any treatment. A small percentage of these fluid collections, approximately 10% to 15%, that persist for more than 3 weeks may develop a capsule and turn out to be pseudocysts, but diagnosis is possible only by follow-up ultrasound or CT scan.18 Table 1 lists the differentiating features of pseudocysts from acute fluid collections. Areas of pancreatic necrosis may appear to be cystic collections of fluid. When spontaneous regression does not take place, they may develop into pseudocysts or pancreatic abscesses. Other terms in popular use include acute pseudocyst, a pseudocyst that is identified to arise after an episode of acute pancreatitis or acute exacerbation of chronic pancreatitis. Chronic pseudocyst is diagnosed in the setting of chronic pancreatitis and without an identifiable antecedent episode of acute pancreatitis. These terms, however, are ambiguous. In a patient with chronic pancreatitis, the preceding attack of acute exacerbation may be mild and localized and hence often undetected.66 Instead, DEgidio and ScheinZ8have proposed a classification system based on pancreatic duct abnormality. Type I or acute postnecrotic pseudocysts occur after an episode of acute pancreatitis, are associated with normal duct anatomy, and rarely communicate with the pancreatic duct. Type 11, also postnecrotic pseudocysts, occur after an episode of acuteon-chronic pancreatitis. The pancreatic duct is diseased but not strictured, and there is often a duct-pseudocyst communication. Type 111, defined as retention pseudocysts, occur with chronic pancreatitis and are uniformly associated with duct stricture and pseudocyst-duct communication. Approximately 75% of cystic lesions of the pancreas are pseucysts, accounting for 10% of cystic lesions, are locald o c y s t ~Retention .~~ ized dilations of pancreatic duct proximal to a site of ductal obstruction caused by chronic pancreatitis or carcinoma. Other cystic lesions include congenital cysts (So/,) and cystic neoplasms (loo/,) (Table 2).

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Table 2. CYSTIC LESIONS OF THE PANCREAS* Pseudocysts (75%)

Neoplastic (10%)

Alcoholism and Mucinous ductal ectasia-head of gallbladder pancreas. Affects elderly men, disease (75%) presents with abdominal pain. Trauma (often in Diffuse dilation of the main children) and pancreatic duct (ERCP) postoperative Mucinous cystic neoplasm (macrocystic adenoma or (25%) cystadenocarcinoma)-tail or body. Younger women (<50 y). Symptoms related to mass effect Nonmucinous tumors-erous cystadenoma (microcystadenoma), papillary cystic tumor, and cystic cavitation of adenocarcinoma Others

Retention cysts (10%)

Congenital (5%)

Polycystic disease Von Hippel-Lindau Cystic fibrosis Dermoid cyst

*The conditions listed here do not include acute fluid collections seen in the patient with acute pancreatitis. ERCP = endoscopic retrograde cholangiopancreatography.

PATHOGENESIS RichteP has elegantly summarized the pathogenesis of pseudocyst formation. In an attack of acute pancreatitis, there is direct leakage of pancreatic juice from the inflamed area of the gland, which accumulates in a space adjacent to the pancreas. Ductular disruption is secondary to pancreatic necrosis, even though the attack need not be clinically severe. The most common site of accumulation of the leaking pancreatic juice is the potential space of lesser omentum (lesser sac) limited anteriorly by the stomach, inferiorly by the transverse mesocolon, laterally by the spleen, and by splenic flexure on the left and the duodenum on the right. The evoked inflammatory response induces the formation of a distinct cyst wall composed of granulation tissue and blood vessels, which organizes with more connective tissue and fibrosis. The cyst cavity contains enzymatic fluid and necrotic debris. Observations supporting the concept that, at its origin, a pseudocyst must have had a communication with the pancreatic duct are as follows. The amylase levels of the aspirated cystic fluid is many times greater than the simultaneous serum levels. Percutaneous drainage of pseudocysts results in a prolonged period of drainage indicating a communicating fistula. Radiologic studies, such as contrast injection into the pseudocyst and endoscopic retrograde cholangiopancreaticography, have clearly demonstrated such a communication in up to two thirds of patientsz7 With time, however, the communication may or may not persist because the inflammatory reaction that follows cyst formation may occlude the fistula.66 A second mechanism is proposed in the pathogenesis of pseudocysts in some patients with chronic pancreatitis. When a branch of

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the pancreatic duct is obstructed by fibrous scarring, inspissated protein, or stone, the ongoing pancreatic secretion proximal to the obstruction leads to a saccular dilation of the duct, filled with pancreatic juice. Such a cyst is truly a retention cyst.2s,38 The formed microcysts can eventually coalesce and lose their epithelial lining as they enlarge. In chronic pancreatitis, pseudocysts are more often seen in those with minimal fibrosis than in those with advanced fibrosis and calculi.4s PATHOLOGY

Macroscopy

Pseudocysts can be single or multiple (Fig. 2). Most cysts (90%) are single. Multiple pseudocysts are seen more often in acute alcoholic pancreatitis.36 The size varies from 2 to 30 cm with estimated volumes reported between 50 and 6000 mL. Small pseudocysts are often located within the pancreas, with nearly one third located in the head and two thirds in the body and tail. They are often located outside the pancreas in the lesser sac, where they may extend to adjacent viscera. Extension into transverse mesocolon may occur because of the anatomic relationship of transverse colon to the pancreas (Fig. 3). The cysts may also extend to the anterior or posterior pararenal space, mediastinurn, and retroperitoneum. Posterior pseudocysts, although rare, may extend inferiorly into the pelvic region and groin, and pseudocysts extending to the scrotum have been encountered. The cysts are often smooth and rounded. Thick granulation tissue separates the cysts from the surrounding structures.

Figure 2. Multiple pancreatic pseudocysts.

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Figure 3. Lesion initially diagnosed as infected pancreatic pseudocyst. Percutaneous catheter drainage was unsuccessful. On exploration, diagnosed to have a malignant cyst.

The cyst contents have been well studied. The fluid may be clear and watery or xanthochromnic or brown because of old blood and necrotic tissue. The amylase, lipase, and trypsin contents are usually markedly elevated, and it is exceptional to find amylase activity lower than serum levels.70The amylase level may decrease in some pseudocysts in existence for a long time. It is hypothesized that the cyst may have lost its communication with the duct system coupled with the possibility that the fluid in the cyst exchanges with the plasma. The aforementioned mechanism also explains spontaneous disappearance of small cysts. Microscopy The cyst wall characteristically is composed of granulation and fibrous tissue without an epithelial lining. In an acute pseudocyst, usually four zones can be distinguished in the wall. The inner zone or zone 1 is narrow and contains hemosiderin pigment and loose connective tissue. Zone 2 is made up of inflammatory and capillary-rich fibrous tissue. The third zone is composed of hyalinized connective tissue that is depleted of cells. The outer zone, or zone 4, consists of capillary-rich fibrous The pseudocyst wall is a dynamic structure associated with a series of continuous biologic changes. The histology of the wall varies according to the age of the pseudocyst. Older cysts have thicker walls with increased collagen, fibronectin, and smooth muscle content. The histologic appearance is independent of the cause with no differences in the structure of the walls between alcoholic and biliary pancreatitis and idiopathic pancreatitis.

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CAUSE

The occurrence of pseudocysts parallels that of pancreatitis and is often seen in patients in their 30s or 40s. Alcohol-related pancreatitis appears to be the major cause in most series, accounting for 59% to 78% of pseudocysts. Most of these studies are retrospective, however. In their prospective long-term follow-up of patients with severe alcohol-related pancreatitis, Imrie4 has observed that alcohol-induced pancreatitis does not have a greater predisposition to pseudocyst formation. Pseudocyst in children15,97 is a known complication of acute pancreatitis and pancreatic trauma. A blunt or nonpenetrating injury, such as in a steering wheel injury in an automobile accident, in which the pancreas sustains a crushing blow is likely to be complicated by a subsequent pseudocyst. Certain surgical procedures, such as partial gastrectomy, may be complicated by pseudocysts when the pancreas is inadvertently torn near its attachment to spleen or when an attempt has been made to dig out a peptic ulcer that has penetrated the pancreas. Pseudocysts may complicate the clinical picture of any cause of acute pancreatitis, including ERCP or pancreatic cancer.

CLINICAL FEATURES

The most common symptom is upper abdominal pain, often across the midepigastrium or distress with an insidious onset. Occasionally the pain becomes increasingly intense simulating that of pancreatic carcinoma. The pain may be referred to the left more than the right hypochondrium with radiation to the back. When there is diaphragmatic involvement, the pain may be pleuritic and even felt in the shoulder. A sudden onset of pain or exacerbation of a preexisting pain signifies hemorrhage into the cyst or peritoneum. Pain is aggravated by eating food, and marked sitophobia and weight loss may mimick pancreatic cancer. Many patients with pseudocysts suffer from anorexia with or without abdominal pain, which may be progressive and associated with nausea and vomiting. Small cysts and even some moderately sized cysts may be totally asymptomatic and discovered only incidentally. Physical examination seldom is diagnostic except in patients with big cysts when the cysts are palpable, move with breathing, are smooth and firm, and are often nontender." Associated jaundice is rare and seen in fewer than 10% of patients.94Pleural effusion, especially on the left, may be a feature. Chylous ascites and portal hypertension have been reported in association with p ~ e u d o ~ y ~ t ~ . ~ ~ Clinically a pseudocyst is suspected (1) when an episode of pancreatitis fails to resolve, (2) when the amylase levels are persistently high, (3) when patient has persistent abdominal pain after clinical resolution of acute pancreatitis, or (4)when an epigastric mass is felt after an episode of acute pancreatitis.

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DIAGNOSIS

There are no definitive laboratory tests for diagnosing a pancreatic pseudocyst. A persistently elevated serum amylase level may be present in 76% of patients with pseudocysts. Plain radiographs of the abdomen also are not useful and only occasionally demonstrate displacement of the gastric bubble or calcification in the cyst wall. Ultrasonography has a sensitivity of 75% to 90% for detecting pseudocysts. CT scanning is currently the most accurate test for demonstrating a pseudocyst with a sensitivity of 90% to 100%. It also is not operator dependent, can be used in obese patients, and gives a precise definition and localization. Ultrasound evaluation, because of its convenience and lower cost, is an ideal method for monitoring pseudocyst size.82 Approximately 10% of pancreatic cysts are neoplastic, such as benign serous cystadenomas, mucinous cystadenomas, and mucinous cystadenocarcinomas (see Fig. 3). Differentiation between pseudocysts and neoplastic cysts is essential for determining optimal therapeutic intervention and specifically before endoscopic or percutaneous drainage. Sand et a1,7O in a prospective study of 22 patients with a cystic lesion in the pancreas who underwent surgery, compared clinical assessment and cyst fluid analysis for differentiating cystic lesions. Based on clinical and radiologic criteria, a cystic lesion was considered a probable pseudocyst when (1)it was preceded by acute pancreatitis of known origin, (2) it was preceded by known chronic pancreatitis, or (3) ERCP showed chronic pancreatic changes. The cystic lesion was considered a probable neoplastic cyst when there was no preceded history of acute or chronic pancreatitis or when ERCP showed normal pancreatogram. Using these clinical and radiologic criteria, they correctly differentiated all pseudocysts and neoplastic cysts. Warshaw et al,S9however, have noted that there is no reliable clinical or radiologic criteria to permit preoperative differentiation of the different types of pancreatic cysts. One third of the cystic tumors referred to them, particularly 90% of mucinous tumors, were misdiagnosed as pseudocysts, and many were inappropriately treated as a result2O Lewandrowski et a153have suggested that percutaneous aspiration and analysis of cystic fluid for viscosity, carcinoembryonic antigen (CEA), CA-125, and cytology can reliably distinguish malignant cystic tumors and potentially premalignant mucinous cystic neoplasms from pseudocysts and serous cystadenomas. They found that CA-125 and CEA levels are lower in pseudocysts and high in neoplastic cysts. Ca 19.9 is nondiscriminatory and may be even higher in pseudocysts than in neoplastic cysts. Ca 19.9 elevation is also common in acute and chronic pan~reatitis.~~ Amylase level is generally high in pseudocysts and low in cystic tumors. Cytologic analysis of cysts, although useful for mucinous cysts (accuracy 88%),is of limited value for serous cystadenomas, and even intraoperative biopsy of cyst wall for frozen section histopathology is unreliable in 20% of cases. Sand et a170 caution that because of the considerable overlap of values, cyst fluid analyses may

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be misleading in an individual patient. Furthermore, although not well studied, there is also the potential risk of tumor seeding and peritonitis after cyst puncture. Therefore, the role for aspiration for diagnosis of a cystic lesion remains to be determined. ERCP is not required for diagnosing a pseudocyst. Controversy exists whether ERCP should be done routinely after a pseudocyst is diagnosed. Proponents of ERCP state a greater than 95% advantage of demonstrating pancreatic ductal abnormalities, approximately 20% incidence of unsuspected multiplicity, and 80% duct-pseudocyst communication. Abnormalities in cholangiogram occur in 20% to 50% patients, mainly in chronic pancreatiti~.~~ Neelon et a160 reported that routine ERCP altered their operative plan in 24 of 41 patients, with 19 patients requiring more extensive drainage of the pancreatic duct by a Peustow procedure instead of just simple drainage of the pseudocyst. In addition, Ahearne et a16advocate that by demonstrating ductal communication or stricturing of the dominant pancreatic duct ERCP may help in the decision processes of selecting internal drainage over percutaneous drainage. In their retrospective analysis, patients treated using these criteria had a lower incidence of adverse outcome than those whose treatment did not follow the aforementioned guideline (12% versus 43%; P< .04). ERCP can exacerbate acute pancreatitis; cause bacterial contamination of the fluid collection; and may unnecessarily increase the extent of operation, without demonstrable outcome advantage.55,87 Hence, ERCP is not routinely indicated in patients undergoing percutaneous drainage and is reserved only for patients who have failed percutaneous therapy.40When done, it should be performed using broadspectrum antibiotic coverage and within 24 hours before drainage. NATURAL HISTORY OF PSEUDOCYST

The advent of ultrasound and CT scan of the abdomen in the 1970s has clearly established that approximately 50% of pseudocysts resolve spontaneously. The exact number varies and is reported to be between 7% and 85?'0.~, 13, 18, y6 The wide variation is because of inclusion of acute fluid collections with pseudocysts, the size of the cysts studied, cause, multiplicity, and duration of follow-up. Size

The size of the pseudocyst is an important predictor of outcome. Nearly all pseudocysts less than 4 cm in diameter resolve 62 Beebe et all3 documented 90% resolution in cysts less spontane~usly.~~, than 4 cm compared to 20% of cysts greater than 6 cm. In the retrospective study by Ye0 et alY6from Johns Hopkins of 75 patients with pseudocysts, 39 were operated on for persistent abdominal pain, pseudocyst enlargement, or pseudocyst complication, and 36 had conservative treat-

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ment alone, regardless of size. All 36 patients had mature cysts, were asymptomatic, and were followed with CT scan for a mean period of 1 year. There was no difference between the two groups as regards the number of pseudocysts per patient, location of the pseudocyst, and wall thickness. The size of the pseudocyst was the only criterion that was significantly different (mean 7.4 cm for the surgical group versus 5.8 cm for the conservatively managed group). Size of the pseudocyst correlated with necessity of surgical intervention; 67% of pseudocysts 6 cm and greater required surgical drainage as opposed to 40% for those less than 6 cm. Of pseudocysts greater than 10 cm in size, 27% were successfully managed without surgery. In a study from University of Nebraska, Nguyen et alblhave observed no difference between pseudocysts greater than 6 cm compared with those less than 6 cm in diameter with respect to rate of spontaneous resolution, need for operative management, pseudocyst complications, recurrence, or mortality. These observations suggest that there are no strict size cutoff criteria mandating intervention. Cause

Pseudocysts occurring after chronic pancreatitis have the lowest rate (0% to 9%) of spontaneous Presence of pancreatic calcification is also a poor prognostic indicator for spontaneous r e s o l ~ t i o nOne .~~ group has reported that no patient with pseudocyst associated with biliary or postoperative pancreatitis underwent spontaneous resolution.61 Traumatic pseudocysts also have a low percentage of spontaneous resol ~ t i o nMortality .~~ was 14% in patients who had pseudocysts complicating an attack of acute pancreatitis and none with pseudocysts complicating chronic pancreatitis, and the mortality rate was four times greater with pseudocysts after biliary pancreatitis than after alcoholic pancreatitisA5 In contrast, in the study of Nguyen et a1,6l although patients with biliary pancreatitis did not have a higher mortality than patients with alcoholic pancreatitis, there were significantly more deaths in patients with pseudocysts associated with postoperative pancreatitis compared with all other groups (29% versus 7%; R . 0 5 ) . Multiplicity

In a study by Goulet et a136of 91 patients with pseudocysts, 13 (14.3%) had multiple pseudocysts. In these 13 patients, only 5 of 28 (17.9%) pseudocysts resolved spontaneously, with complete resolution of all pseudocysts in only one patient. Multiplicity was not found to be a significant risk factor for failure of spontaneous resolution in the study of Nguyen et a1.61 Duration of Follow-Up

It is generally believed that most pseudocysts that are likely to resolve spontaneously do so within 6 weeks, and cysts that persist for 8

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to 10 weeks are unlikely to resolve spontaneously. Bradley et all8 reported in 1979 that cysts fewer than 6 weeks old had 40% resolution. In contrast, pseudocysts of 7 to 12 weeks' duration exhibited a markedly decreased rate of spontaneous resolution (8%), and none of the pseudocysts present for 13 to 18 weeks underwent spontaneous resolution. Moreover, complications increased from 20% to 46% and 75%. In contradiction, in the study of Ye0 et a196from Johns Hopkins, observation with serial CT scans for a mean period of 1 year revealed spontaneous resolution in 60% of 36 patients. The pseudocysts remained stable or decreased in size in 40%. There was only one complication, a case of self-limited hemorrhage into the cyst with no mortality. In another retrospective study, Vitas and S a r P from the Mayo Clinic reviewed the course of 68 patients with asymptomatic pseudocysts and noted that 63% remained asymptomatic, after a follow-up averaging 51 months. Serious complications were seen in only six (9%) patients including intracystic hemorrhage in three, perforation in two, and cyst infection in one. Three of the six complications occurred in multiloculated pseudocysts. Twenty-four (35%) patients underwent operative therapy; 5 patients had emergency operations for complications, and 19 underwent elective drainage for pain, asymptomatic enlargement, or gastric/biliary obstruction. In the latter two studies, most of the pseudocysts were small, of average size 5.8 cm and 5.5 cm, and these would have been managed conservatively anyway. The old concept, however, that observation more than 6 weeks is fruitless and hazardous is no longer true. TIMING OF DRAINAGE

The accepted opinion has been as follows: (1) a pseudocyst that occurs after an episode of alcohol-related pancreatitis has to be observed for 4 to 6 weeks with regular follow-up ultrasound examinations of the abdomen. (2) After 6 weeks observation should continue if the size of the cyst is less than 6 cm and the patient is asymptomatic or if there is decrease in size. (3) Therapy is indicated if the patient is symptomatic or if the cyst size is more than 6 cm, the cyst is increasing in size, the cyst is infected, or there'is a suspicion of malignancy. (4)Observation is unnecessary, and immediate drainage is safe in cysts that have a mature wall or in those arising in chronic pancreatiti~.~~ Similarly, presence in the serum of an isoamylase (old amylase) is a reliable indicator for safety of internal drainage, regardless of the apparent age of the pseudocyst. Warshaw and Rather9*observed that in the presence of old amylase, 14 of 14 pseudocysts were suitable for internal drainage, but that in its absence, 4 of 5 pseudocysts required external drainage. The current literature suggests that the old 6 cm-6 weeks criteria for intervention should be a relative rather than an absolute indicator. Asymptomatic pseudocysts regardless of size and duration can be safely observed, provided that they are carefully monitored and are not increasing in size. Intervention is mandatory only in the presence of symptoms, complications, or increase in size or if there is any doubt of malignancy.

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METHOD OF DRAINAGE Currently, at least three major modes of therapy are available: (1) percutaneous drainage, (2) endoscopic drainage, and (3) surgical intervention. The choice often depends on patient criteria and physician expertise (i.e., radiologist, endoscopist, surgeon).

Percutaneous Drainage Percutaneous drainage or interventional radiologic therapy involves either percutaneous aspiration or percutaneous catheter drainage under sonographic, CT, or fluoroscopic guidance. As compared to simple aspiration in percutaneous catheter drainage, a 7 to 12 F pigtail catheter is inserted in the pseudocyst over a needle-inserted guidewire. Percutaneous aspiration is ideal or safe only for diagnosis but is ineffective for therapy. Chronic pseudocysts have thick walls, and needle aspiration may not be effective in collapsing the walls. The cysts with ductal communication, which may be in 40% to 60% of cases, reaccumulate fluid usually within 24 hours after a s p i r a t i ~ nAn . ~ ~analysis of five studies that predominantly used the transperitoneal or retroperitoneal route of needle aspiration alone carried a high rate of recurrence (63%) and failure (54%). Repeated aspiration increases the risk of complication~.~~ Continuous catheter drainage has more impressive results, with a low failure rate of only l6%, recurrence rate of 7%, relatively low complication rate of l8%, and mortality rate of 2% with most series reporting no deaths.40The most serious complication is introduction of secondary infection or catheter-related infection Other complications include occlusion or displacement of the catheter, cellulitis at the site of entry, and accidental puncture of the spleen. Rare complications reported are myocardial infarction; gastrointestinal hemorrhage; and fistula to the stomach, jejunum, or cecum. Duration of catheter drainage ranges from 7 to 210 days (average, 2 to 3 weeks). Although we have only limited data, adjunctive octreotide therapy appears to decrease significantly catheter drainage, resulting in decreased duration of catheter drainage and increased closure of pancreatic fistulas.26 Percutaneous drainage is not the procedure of choice in the presence of a stricture of the main pancreatic duct because of the risk of a permanent external fistula. Percutaneous catheter diagnosis is less effective in multiple and loculated pseudocysts. Contraindications to percutaneous catheter diagnosis include suspicion of malignancy, intracystic hemorrhage, and presence of pancreatic ascites. Percutaneous catheter drainage should be the initial mode of treatment for poor-risk patients in need of pseudocyst drainage, for patients with symptomatic or expanding immature cysts, and for patients with infected pseudocysts.

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Percutaneous Pancreatic Cystogastrostomy

Using a combination of ultrasonography and gastroscopy, one end of a double-pigtail catheter is placed in the stomach and the other end in the This technique has the advantage of establishing a communication with the stomach allowing internal drainage and preventing a pancreatic cutaneous fistula. Endoscopic Therapy

Rodgers et aF7in 1975 first reported endoscopic transgastric needle aspiration of pancreatic pseudocyst. Kozarek et al5I in 1985 described the first successful endoscopic drainage of pancreatic pseudocysts. Since then, expertise in therapeutic endoscopy has made it feasible to drain pancreatic pseudocysts through an endoscopic approach, which may be transenteric through the stomach (endoscopic cystogastrostomy) or duodenum (endoscopic cystoduodenostomy) or through the pancreatic duct (transpapillary drainage). Over the last 2 to 3 years, a number of articles have reported endoscopic drainage of pseudocysts in 20 to 30 patients. The technical feasibility as well as the suitability of this approach instead of surgery has been established. Success and recurrence rates are similar to those of open surgery.22The morbidity and mortality when performed by endoscopic experts are notably lower than for surgery. Lo et a157have reported the results of 437 patients managed with endoscopic drainage of pseudocysts. Analysis of collected data indicates that resolution of pseudocyst can be achieved in nearly 90% with recurrence rates of l6%, morbidity of 20%, and mortality of 0.23%. Although the earlier reported mortality has been as high as 5%,6*most series have reported no mortality.", 14,23, 24, 29, 50, 75 Transpapillary Drainage

The technically demanding, transpapillary drainage obviously is successful only when the cyst is in communication with the duct system. Communication between the pseudocyst and ducts occurs two thirds of the time and is more common in pseudocysts associated with chronic pancreatitis than those associated with acute pancreatitis (49% versus 20%). ERCP before cyst drainage should establish the communication. Subsequently a fine guidewire is advanced aong the main pancreatic duct into the pseudocyst or beyond. A pancreatic duct sphincterotomy is then performed, and a 5 or 7 F stent is passed over the wire and left in situ for a mean period of 3 months. A potential serious complication is introduction of infection and abscess formation; therefore antibiotic prophylaxis before ERCP is required. Successful drainage was accomplished in 84% of 117 patients with a recurrence rate of 9%, a complication rate of 12% (14 patients), and no deaths.12The most frequent complication (six patients) was acute pancreatitis, which was mild and selflimiting, followed by secondary pancreatic pseudocyst infection (three

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patients) that resolved with stent change. Late development of ductal irregularities similar to those seen with chronic pancreatitis is seen in 50% of patients after transpapillary ~ t e n t i n g . ~ ~ Transenteric Drainage Transenteric drainage (endoscopic cystogastrostomy or endoscopic cystoduodenostomy) performed endoscopically can be achieved ideally only in cases in which a pseudocyst is firmly adherent to the gastrointestinal tract, and it causes a bulging into the gastric or duodenal lumen. Ideally, in addition to obvious visible compression on endoscopy, the distance between the cyst and the lumen should not exceed 1 cm on imaging. Endoscopic ultrasound, currently an integral part of transenteric drainage, is used to determine the size, location, adherence to the stomach and duodenal wall, distance between the cyst and lumen, and presence of submucosal vessels.32 The cyst is punctured with a diathermic needle at the point of maximal bulging. A guidewire is passed into the cyst quickly, and contrast medium is injected to define the anatomy of the cyst and confirm the entry into the cyst. With a standard spincterotome, the opening is increased from 3 to 50 mm. Balloon dilatation has also been used to enlarge the opening and minimize risk of hemorrhage. One or two large (7 to 10 F) straight or double-pigtail stents are inserted into the cyst and left in place for 2 to 4 months or until ultrasonographic confirmation of cyst resolution. Cystogastrostomies are especially prone to early closure if not stented, resulting in recurrence rates as high as 20%. Use of nasogastric catheter is optional. The complications, bleeding, and perforation can be life-threate~~ing.~~ A cumulative series of transenteric drainage reported endoscopic cystogastrostomy was successful in 82% of 50 patients, with a recurrence rate of 18%. There were no deaths, but major complications were bleeding (8%)and perforation (8%).Similarly, in a total cumulative experience of 71 patients, endoscopic cystoduodenostomy was successful in 89% with a recurrence rate of only 6%. Complications were less frequent, with severe bleeding in 4% and perforation in 4y0.'~ Overall, these procedures appear to be acceptable substitutes for surgical treatment.5,44 The low complication rates, recurrence rates, and high degree of success in the hands of a group of highly competent endoscopists, however, cannot provide the basis for advocating the procedure for general use. Endoscopic expertise is required, and only experienced endoscopists in selected centers should attempt these otherwise risky procedures. Appropriate surgical backup is also needed.=, 91 Surgical Intervention

In the opinion of most surgeons and many senior gastroenterologists, surgical drainage is still the treatment of choice despite the availability of other less invasive measures.%An open surgical approach is

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chosen for all patients with recurrent pseudocysts, pseudocysts combined with common duct or duodenal stenosis, symptomatic pseudocysts associated with a dilated pancreatic duct, or pseudocysts for which a diagnosis of cystic neoplasm cannot be excluded. Surgery offers the advantage of obtaining a biopsy specimen of the cyst wall. Any type of endothelium in the wall of the suspected pseudocyst indicates a true cyst or a cystic neoplasm. Preoperative ERCP is helpful, although not always needed. Surgical procedures for pancreatic pseudocysts include external drainage; internal drainage, which can take the form of cystogastrostomy, cystoduodenostomy, or cystojejunostomy; and excision. External Drainage

External drainage of the cyst is indicated for immature cysts (thin, nonfibrous wall that does not hold sutures), cysts with grossly infected contents, and ruptured cysts. It is associated with a mortality rate of lo%, recurrence rate of l8%, and persistent pancreatic fistula in 10% that may necessitate a distal pancreatectomy or drainage into a roux-en-Y loop of jejunum.2oThe high mortality rate is because of the often poor condition of the patient in whom the procedure is attempted. Internal Drainage

Internal drainage is the procedure of choice for all uncomplicated mature pseudocysts. Cystogastrostomy is done for cysts densely adherent to the posterior wall of the stomach. Cystoduodenostomy is indicated for pseudocysts in the head and uncinate process of the pancreas. Cystojejunostomy is appropriate for all other cysts and extremely large pseudocysts (>15 cm) so as to achieve dependent drainage. Overall, in the cumulative review of 14 studies comprising 1032 patients, internal drainage was associated with a mortality rate of 5.8% and a complication rate of 24%.40The mortality rate has been decreasing over the years. The collected mortality rates for the period 1984 to 1992 is 3% (5.2% for cystogastrostomy, 1.9% for cystojejunostomy, and 0% for cystoduodenostomy) and recurrence rate is only 8%.'O Excision

Excision of pancreatic pseudocysts in the body and tail by distal pancreatectomy with or without splenectomy is rarely indicated for pseudocysts. It is indicated for treatment of the complication of hemorrhage from pseudoaneurysm and for true cysts or cystic neoplasms discovered by biopsy of the cyst wall at the time of surgery. Drainage procedures are preferred because resection is technically more difficult and is associated with loss of pancreatic function and greater morbidity and mortality.

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Laparoscopic Surgery

The popularity of laparoscopic surgery extends to the treatment of pseudo~ysts.~~, 81 Anecdotal reports have been reported with authors describing various surgical techniques, including laparoscopic intracorporeal sutured gastrocystostomy and enterocystostomy or laparoscopic intraluminal cystogastrostomy without or with an endostapler device. Risks of significant contamination of the abdominal cavity, free perforation of the stomach, hemorrhage, and insufficient communication exist. It appears that the laparoscopic approach to drain pseudocysts may be feasible only in a few selected cases. The experience is limited; technically, laparoscopic surgery is difficult to perform; and in the absence of a standardized proven technique, it should be performed only in the setting of a prospective trial.

COMPARISON OF TREATMENT MODALITIES Percutaneous Catheter Drainage Versus Surgical Treatment

In a retrospective review of 68 patients treated between 1969 and 1987 at Lund, Sweden, 9 with a median cyst size of 4 cm were treated conservatively, with spontaneous resolution seen in 8 (89%). The remaining 59 patients required drainage; 22 patients underwent percutaneous drainage (median size, 9 cm), and 37 had surgical treatment (median size, 11 cm). There was no difference in the failure rates (14% versus 8Yo) or need for additional surgery (9% versus 13%). The only death (mortality 2.7%) occurred in the surgically treated group after external drainage.7 Similarly, in another retrospective review from Charleston, South Carolina, Adams and Anderson2 compared 52 patients treated with percutaneous drainage to 42 patients who had internal drainage. There was no difference in the incidence of major complications (7.7% versus 16.7%) or need for subsequent operation (19.2% versus 9.5%). Mortality was significantly greater in the internal drainage group (0 versus 7.1%, P<.05), however. The principal disadvantage of percutaneous catheter drainage included prolonged pancreatic fistula (mean catheter drainage, 42 days) and secondary drain tract infection rate of 48%. When the period of 1982 to 1990 was compared to the period 1964 to 1981, there was a significant increase in the number of patients managed by percutaneous catheter drainage (52% versus 10%) and decrease in internal drainage procedures (16% versus 38%). Although the morbidity rates were similar (28% versus 26%), there was a significant decrease in overall mortality (1% versus 9%, P<.05).' In a prospective study carried out over 10 years by Lang et a1,52 patients with pancreatic pseudocysts were assigned alternately to operative (26 patients) or percutaneous drainage (26 patients). There was no

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significant difference between resolution (88% versus 77%) or 6 month recurrence rates of 15% and 12%. In contrast to the previous data, in the experience of Criado et a1,25 successful long-term outcomes in 42 patients with symptomatic pseudocysts were seen in only 21% after percutaneous drainage, with almost 60% requiring subsequent operative drainage. Rao et aP5 retrospectively compared the outcome of 52 patients operated on initially with 18 atients in whom an initial nonsurgical (percutaneous catheter drainage 15, endoscopic drainage in 2, and both in 1) drainage procedure failed and required subsequent surgical drainage. Morbidity was twice as frequent in the initial nonoperative group (14% versus 33%), as was the time from initial attempt at drainage to pseudocyst resolution (20 versus 104 days; P = .01). A major criticism of this study is that the investigators did not compare the results of surgery to all patients treated nonsurgically or mention the failure rate of nonsurgical treatment. Overall, despite its drawbacks, percutaneous drainage is a safe, effective treatment of pancreatic pseudocyst.

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Endoscopic Versus Surgical Treatment

In a retrospective study from Hamburg, Germany, surgical or endoscopic management performed between 1985 and 1990 resulted in similar success rates of 50% and 52% after an average period of 33 months’ f01lowup.~~ Similarly, Barthet et allo found identical rates of 72% resolution, 15%morbidity, and 1%mortality in 71 cases of endoscopic drainage and 73 cases of surgical drainage. OTHER THERAPY SOMATOSTATIN

Somatostatin has a profound inhibitory effect on the pancreatic exocrine secretion, and this property of somatostatin has been used in the treatment of pseudocysts. Gullo and Barbara39used somatostatin as the primary therapy for pseudocysts. They treated seven patients with pseudocysts with octreotide (100 p.g three times a day for 2 weeks). Four of the seven demonstrated a decrease in size. More significantly, there was a definite decrease in the intensity of pain. Octreotide has also been used in conjunction with percutaneous catheter drainage of pseudocysts, which resulted in a shortened drainage time.26The role of somatostatin in the management of pseudocysts is not clear. Prospective, controlled trials are necessary to prove its efficacy. COMPLICATIONS

The principal complications of untreated pancreatic pseudocyst are infection, hemorrhage, rupture, pancreatic ascites, and obstruction (Table 3).

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Table 3. COMPLICATIONS OF PANCREATIC PSEUDOCYSTS Local (Pancreatic) Infection Hemorrhage Rupture Pancreatic ascites Shock Peritonitis Adjacent Organ Involvements Gastrointestinal tract Esophagus Secondary achalasia Mechanical dysphagia Stomach Gastric outlet obstruction Fistula Intramural gastric mass Duodenal Obstruction Fistula

Colonic Fistula Colonic stenosis Obstruction Rectal bleeding Liver Common bile duct obstruction Genitourinary tract Fistula Obstruction/ hydronephrosis Chest Pleural effusion Mediastinal extension Vascular Arterial Erosion of gastroduodenal artery Erosion of splenic artery Venous Splenic vein thrombosis Portal vein thrombosis

Infection

Approximately 10% of pseudocysts become secondarily infected.n CT scanning is the test of choice that suggests secondary infection. A characteristic sign is a low-density fluid collection in a defined cavity that contains gas bubbles. Diagnosis of an infected pseudocyst is confirmed by percutaneous aspiration and the presence of bacteria on Gram stain or positive bacterial culture. This finding alone, however, does not quantitate infection in the absence of frank pus or systemic manifestations of sepsis.59Percutaneous drainage is the treatment of choice and should be attempted initially. It is successful in approximately 85% of cases3 Surgical drainage is performed when percutaneous drainage is not curative. The prognosis for an infected pancreatic pseudocyst is extremely good with little mortality.77 Rupture

Rupture of the pseudocyst is seen in less than 3% of patients55and may present as an acute abdominal event or a silent event producing 56 Sudden rupture in to the pancreatic ascites or pleural peritoneum produces severe peritonitis necessitating emergency surgery and is often Spontaneous drainage and amelioration of symptoms result when a pseudocyst ruptures into the hollow gastrointestinal tract (Fig. 4).Pseudocyst rupture may be accompanied by vomiting or diarrhea. Hematemesis, melena, or massive lower gastrointestinal hemorrhage may occur from erosion into the gastrointestinal tract.” On rare occasions, rupture into the portal vein or the urinary tract has been reported.”, 98

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Figure 4. Barium enema demonstrating pseudocyst communicating with the transverse colon.

Pancreatic Ascites Pancreatic ascites is most commonly secondary to leakage from a pseudocyst (70%) or pancreatic duct (10% to 20%). It rarely develops after disruption of a duct after trauma, lymphatic blockage, or portal hypertension. It is characterized by the presence of straw-colored or blood-tinged ascitic fluid with high amylase levels (usually >lo00 units/ dL; range, 205 to 97,000 units) and protein (usually B2.5 g/dL; range, 2.1 to 5.7). ERCP is the procedure of choice to demonstrate the site of leakage.71Medical management consisting of total parenteral nutrition and octreotide should not be continued for more than 2 to 3 weeks. Definitive surgical treatment, which entails either resection of the body and tail of the pancreas or internal drainage, results in 100% survival, little morbidity, and no recurrence of ascites.

Pancreatic Fistula Most pancreatic fistulas result from external drainage of a pseudocyst or abscess. They eventually close spontaneously. Octreotide (Sandostatin) is helpful in decreasing the output of the fistula and expediting closure. Surgical intervention may be indicated if the fistula persists.

Pseudoaneurysm Massive hemorrhage occurs in approximately 5% to 10% of patients 19, 85 Most comwith pseudocyst and is the most feared c~mplication.~, monly, there is massive bleeding into the gastrointestinal tract, followed

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by intra-abdominal bleeding, and rarely there is bleeding into the pancreatic duct (hemosuccus pancreaticus). Erosion of a major pancreatic or peripancreatic vessel leads to free rupture or formation of pseudoaneurysm that subsequently ruptures.31The splenic artery is the most commonly involved vessel followed by the pancreaticoduodenal and gastroduodenal arteries, and the left gastric, hepatic, and small intrapancreatic arteries are impllicated infrequently. Pseudoaneurysm should be suspected in the event of repeated episodes of gastrointestinal bleeding, presence of an enlarging pulsatile abdominal mass, or an abdominal bruit and in patients with increasing abdominal pain. Bolus dynamic CT scan is the most useful initial diagnostic test. It detects the presence of hemorrhage (attenuation >30 HU) and pseudoaneurysms. Angiography is then the procedure of choice for both identification of the source of bleeding and therapy by emboli~ation.~~ Surgical intervention is indicated in patients who are hemodynamically unstable or when embolization is technically not possible or when it fails to stop the bleeding. Angiography should be attempted preoperatively. Angiography allows identification of the site and source of bleeding, facilitates surgical control of bleeding, and eliminates unnecessary harmful extra dissection. Surgical options consist of (1) proximal and distal ligation of bleeding vessels with drainage of pseudocyst or necrotic tissue and (2) distal pancreatectomy when bleeding arises from the body or tail of the pancreas.88 Obstruction Pseudocysts can obstruct any part of the gastrointestinal tract: esophagus,M,95 stomach: duodenum, small intestine or colon, urinary the vena cava manifesting as lower extremity edema,16or portal vein leading to portal hypertension. Evidence of obstruction necessitates drainage of the pseudocyst. Jaundice Jaundice is seen in approximately 10% of patients with pseudocysts. In descending order of frequency, it is caused by hepatic dysfunction, pressure by the pseudocyst, and stenosis of the intrapancreatic portion of the distal common bile duct from pancreatitis and choledocho94 ERCP is helpful in delineating the cause and in planning lithia~is.~~. the appropriate management. SUMMARY

A better definition of a pseudocyst that clearly separates it from acute fluid collection, improvements in imaging studies, and a better

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understanding of the natural history of pseudocysts have changed the concepts regarding their management. The old teaching that cysts of more than 6 cm in diameter that have been present for 6 weeks should be drained is no longer true. Indications for drainage are presence of symptoms, enlargement of cyst, complications (infection, hemorrhage, rupture, and obstruction), and suspicion of malignancy. The a ailable forms' of therapy include percutaneous drainage, transendos opic approach, and surgery. The choice of procedure depends on a umber of factors, including the general condition of the patient; size, number, and location of cysts; presence or absence of communication of the cyst with the pancreatic duct; presence or absence of infection; and suspicion of malignancy. Expertise of the radiologist and the endoscopist is also a major deciding factor in the choice of therapy. Percutaneous catheter drainage is safe and effective and should be the treatment of first choice in poor-risk patients, for immature cysts, and for infected pseudocysts. Contraindications include intracystic hemorrhage and presence of pancreatic ascites. For mature cysts, in skilled hands, endoscopic drainage should be given the first preference. It is less invasive, less expensive, and easier to perform with better outcomes in smaller pseudocysts and pancreatic head pseudocysts. Endoscopic expertise is limited, however, and at present endoscopic drainage cannot be advocated as the procedure for general use. In the absence of endoscopic expertise, percutaneous catheter drainage is the procedure of choice. Surgical treatment has been the traditional approach and is still the preferred treatment in most centers. Multiple pseudocysts, giant pseudocysts, presence of other complications related to chronic pancreatitis in addition to pseudocyst, and suspected malignancy are best managed surgically. Surgery is also the backup management in the event that percutaneous or endoscopic drainage fails. Because radiologic diagnosis of pseudocysf may be inaccurate in 20%; it is imperative to be sure that the cystic structure is not a neoplasm before percutaneous or endoscopic drainage. There have been no prospective, randomized trials that have evaluated the results of the three major modalities of therapy (percutaneous, endoscopic, and surgical), and before one can definitely recommend percutaneous drainage or endoscopic approach as the preferred initial mode of therapy, further studies are needed.

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References 1. Adams DB, Anderson MC: Changing concepts in the surgical management of pancreatic pseudocysts. Am Surg 58:17%180,1992 2. Adams DB, Anderson MC: Percutaneous catheter drainage compared with internal drainage in the management of pancreatic pseudocysts. Ann Surg 215:571-578, 1992 3. Adams DB, Harvey TS, Anderson MC: Percutaneous catheter drainage of infected pancreatic and peripancreatic fluid collections. Arch Surg 125:1554-1557, 1990 4. Adams DB, Zellner JC, Anderson MC: Arterial hemorrhage complicating pancreatic pseudocyst: Role of angiography. J Surg Res 54:150-156, 1993

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5. Adkisson KW, Baron TH, Morgan DE: Pancreatic fluid collections: Diagnosis and endoscopic management. Semin Gastrointest Dis 9:61-72, 1998 6. Aheame PM, Baille JM, Cotton PB, et al: An endoscopic retrograde cholangiopancreaticography (ERCP)-based algorithm for the management of pancreatic pseudocysts. Am J Surg 163:lll-116, 1992 7. Anderson R, Janzon M, Sundberg I, et al: Management of pancreatic pseudocysts. Br J Surg 76:550-552, 1989 8. Aranha GV, Prinz RA, Esguerra AC, et al: The nature and course of cystic pancreatic lesions diagnosed by ultrasound. Arch Surg 118:48&488, 1983 9. Aranha GV, Prim RA, Greenlee HB, et al: Gastric outlet and duodenal obstruction from a inflammatory pancreatic disease. Arch Surg 119S33-835, 1984 10. Barthet M, Buggalo M, Moreira LS, et al: Management of cysts and pseudocysts complicating chronic pancreatitis: A retrospective study of 143 patients. Gastroenterol Clin Biol 17270-276, 1993 11. Barthet M, Sahel J, Bodiou-Bertei C, et al: Endoscopic transpapillary drainage of pancreatic pseudocsyts. Gastrointest Endosc 42:208-213, 1995 12. Beckingham IJ, Krige JE, Bomman PC, et a1 Endoscopic management of pancreatic pseudocysts. Br J Surg 841638-1645, 1997 13. Beebe DS, Burburick MP, Onstad GR, et al: Management of pancreatic pseudocysts. Surg Gynecol Obstet 159:562-564, 1989 14. Binmoeller KF, Siefert H, Walter A, et a1 Transpapillary and transmural drainage of pancreatic pseudocyst. Gastrointest Endosc 42919-224, 1995 15. Bosman-Vermeeren JM, Veerman-Wauters G, Broos P, et al: Somatostatin in the treatment of a pancreatic pseudocyst in a child. J Pediat Gastroenterol Nutr 23:442425,1996 16. Bowman MV, Litin SC, Binkovitz LA, et al: Pancreatic pseudocysts that compressed the inferior vena cava and resulted in edema of the lower extremities. Mayo Clin Proc 671085-1088, 1992 17. Bradley EL: A clinically based classification system for acute pancreatitis. Arch Surg 128:58&590, 1993 18. Bradley EL, Clements JL, Gonzalez AC: The natural history of pancreatic pseudocysts: A unified concept of management. Am J Surg 137135-141, 1979 19. Bresler L, Boissel P, Grosdidian J: Major hemorrhage from pseudocysts and pseudoaneurysms caused by chronic pancreatitis: Surgical therapy. World J Surg 15:649-653,1991 20. Bumpers HL, Bradley EL I11 Treatment of pancreatic pseudocysts. In Howard J, Idezuki Y, Ihse I, et a1 (eds): Surgical Diseases of Pancreas. Baltimore, Williams & Wilkins, 1998, pp 423-432 21. Cameon JL: Chronic pancreatic ascites and pancreatic pleural effusions. Gastroenterology 74:134-140, 1978 22. Carr-Locke DL, Pseudocyst: Who should treat-the endoscopist, surgeon or radiologist. Annual Postgraduate Course 2B40M18, 1996 23. Catalan0 MF, Geenen JE, Schmalz MJ, et al: Treatment of pancreatic pseudocysts with ductal communication by transpapillary pancreatic duct endoprosthesis. Gastrointest Endosc 423214-218, 1995 24. Cremer M, Deviere J, Engelholm L Endoscopic management of cysts and pseudocysts in chronic pancreatitis: Long-term follow-up after 7 years of experience. Gastrointest Endosc 35:l-9, 1989 25. Criado E, DeStefano AA, Weiner TM, et al: Long term results of percutaneous catheter drainage of pancreatic pseudocysts. Surg Gynecol Obstet 175293-298, 1992 26. DAgostino HB, VanSonnenberg E, Sanchez RB, et al: Treatment of pancreatic pseudocyst with percutaneous drainage and octreotide. Radiology 187:685-688, 1993 27. DEgidio A, Schein H: Percutaneous drainage of pancreatic pseudocysts: A prospective study. World J Surg 16141, 1991 28. DEgidio A, Schein M: Pancreatic pseudocysts: A proposed classification and its management implications. Br J Surg 78:981-984,1992 29. Deviere J, Bueso H, Baize M, et al: Complete disruption of the main pancreatic duct: Endoscopic management. Gastrointest Endosc 42:445451, 1995 30. Elechi EN, Calender CO, Leffal LD, et a1 The treatment of pancreatic pseudocysts by external drainage. Surg Gynecol Obstet 148707-710, 1979

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Address reprint requests to C. S. Pitchumoni, MD, FRCP(C), MPH Director of Medicine Our Lady of Mercy Medical Center 600 East 233rdStreet Bronx, NY 10466