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ACUTE PANCREATIC AND PERIPANCREATIC FLUID COLLECTIONS
Vrishali Patil*, Surinder K Mathur* *Senior Resident; **Professor and Head, Department of Surgical Gastroenterology, Bombay Hospital Institute of Medical Sciences.
Pathophysiology and Management
There is a lot of confusion about the definitions and management of acute fluid collections in acute pancreatitis, approach to diagnosis and the management policy to be followed. The present article defines the fluid collections and presents a rationalised policy about the various diagnostic and therapeautic modalities in the management of fluid collections.
Definition
According to the Atlanta international symposium1 in 1993, acute fluid collections are defined as the collections which occur early in the course of acute pancreatitis and are located in or near the pancreas and always lack a wall of granulation or fibrous tissue. They are found in more than 50% patients with moderate to severe pancreatitis. They represent a serous or exudative reaction to pancreatic injury and inflammation. Since acute fluid collections do not have a communication with the pancreatic duct, they do not contain high concentration of pancreatic enzymes and the fluid composition is similar to that of plasma. Table 1 gives the differentiating features between the acute fluid collections and acute pseudocyst.2
Natural history
Majority (85%) of fluid collections resolve spontaneously, however few persist, get walled of and develop into pseudocyst over 6-8 weeks. Fluid collections are frequently found along the anterior surface of the gland.3 The fluid may perforate into the lesser sac or extend beyond the pancreas into the anterior, posterior pararenal space, conforming to the space of the compartment. When the fluid escapes from the lesser sac into the greater peritoneal cavity through the foramen of Winslow, it produces pancreatic ascites. More commonly lesser peritoneal sac fluid escapes into the fissure ligamentum venosum, that separates the caudate lobe of liver.
Presenting symptoms
Majority are asymptomatic by themselves and detected on followup imaging during the course of acute pancreatitis. However a small percentage of patients do become symptomatic and may produce :
1.Upper abdominal discomfort due to large collections.
2.Compression of the GIT e.g. stomach, duodenum producing fullness or vomiting especially after meals.
3. Sudden onset pain, increase in size of lump, associated with fall in haemoglobin due to bleed from pseudoaneurysms of adjacent vessels.
4.Pain and fever due to infection
5.Rupture into the peritoneal cavity leading to pancreatic ascites.
6.Jaundice secondary to bile duct compression.
INVESTIGATIONS
Ultrasound is helpful in detecting but fails to give information about the pancreas. Rapid infusion CT scanning provides the most accurate information about presence of fluid collections, morphology of pancreas and associated necrosis. [4] Heterogeneous densities in peripancreatic fluid represents a combination of fat necrosis with fluid collections. The possibility of infection is determined by the clinical findings of rising fever, tachycardia, raised white cell count, air bubbles in fluid collections.
Fig 1 : Management of peripancreatic fluid collections (USG/CT)
MANAGEMENT OF FLUID COLLECTIONS
Since a spontaneous resolution of these fluid collections is known to our in majority of cases, they do not require any specific therapy. However those which either fail to resolve within six weeks or become symptomatic develop complications (as mentioned above) require some form of drainage.
Modalities of treatment available for pancreatic and peripancreatic fluid collection :-
Nonsurgical
1. Radiological - Percutaneous drainage (USG/CT guided)
2. Endoscopic - a) Stenting for disrupture of pancreatic duct. b) Drainage - Transgastric; Transampullary
Surgical
a) External drainage
b) Pancreatic necrosectomy
NON SURGICAL TREATMENT
With emergence of increasing expertise in interventional radiology such as percutaneous drainage, surgical procedures can be avoided or delayed until the patients condition is stable.
1. Percutaneous drainage : It involves either
a.percutaneous aspiration
b.percutaneous catheter drainage
Percutaneous drainage is usually done under antibiotic cover
A 7-12 Fr pigtail catheter is inserted into the collection over a needle inserted guidewire under radiologic screening (USG/CT)
Subsequent scans are done to assess the collection.
The catheter is usually placed for 4-6 weeks.
Percutaneous drainage is ideal for : accessible, well locaulated, single, small collections with low Ransons score (Less than four), APACHE II less than 16.5
Advantages of percutaneous drainage
1.It avoids the morbidity of surgery
2.It is safe in expert hands
3.It can be done under local anaesthesia.
Endoscopic procedures
The pre-requisite for endoscopic drainage is ductal disrupture. Endoscopic drainage is indicated in
•Leaking fluid collections leading to ascites
•Large fluid collections producing complications.
Methods : Trans gastric, Trans ampullary i.e. either nasopancreatic or pancreatic duct stenting
Endoscopic treatment corrects a pancreatic duct disruption by decompressing the pancreatic duct system. It relieves downstream obstruction.
COMPLICATIONS
1.Infection : by introducing secondary infection6
2.The catheter can get clogged and become nonfunctional or displaced7
3.Accidental puncture of visceral organs like spleen
4.Haemorrhage
5.Fistulation to stomach, jejunum or colon.
6.Recurrence of fluid collection
Surgical methods
The decision to operate a patient with large fluid collection is often based on clinical signs of inflammation regardless of the acute bacteriological status of collection and necrosis. Fluid collections associated with alcoholic and biliary pancreatitis usually require surgical mode of treatment.
It involves : a) External drainage. b) Necrosectomy with drainage of collections.
Indications
1.Multiple collections
2.Large collections
3.Inaccessible sites for percutaneous methods
4.Infected collections with thick fluid
5.Failure of percutaneous drainage
6.Presence of yeast on aspirate culture also is an indication for surgical treatment4
7.Associated with necrosis
Complications following surgical methods
1.Prolonged length of hospital stay
2.Morbidity associated with surgery
3.Reoperations
SUMMARY
Most of the pancreatic and peripancreatic fluid collections resolve spontaneously and are not life threatening. A better definition of fluid collections, improvement in imaging studies and expertise in interventional radiology are a major deciding factors in choice of treatment of fluid collections. Percutaneous drainage is safe and effective and should be the treatment of first choice in poor risk patient with small collections. In event of fluid collection associated with necrosis percutaneous drainage followed by laparoscopic evacuation of necrotic debris is possible. Surgical treatment is the backup management in the event that percutaneous treatment fails. Patients who ultimately require surgery are more stable after 7-10 days of catheter drainage and are most likely to require only one operation, as during the drainage period the infections coalesce which facilitates surgical debridement of necrotic material. Early diagnosis, clinical vigilance in detecting complications, referral of patients to specialized centres before they become morbid, ensures state of art multidisciplinary management and hastens outcome in acute pancreatitis.
REFERENCES
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11.Chaudhary A, Dhar P, Sachdev Agarwal. Surgical management of pancreatic necrosis presenting with locoregional complications. Br J Surg 1997; 84 : 965-8.
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