Disorders of the Pancreas

In the elderly, the most common disorders of the pancreas are traumatic injury, pancreatitis, and cancer. Pancreatic cancer is discussed in Ch. 113.

Traumatic Injury

Penetrating injuries are diagnosed by exploration of the lesser sac and mobilization of the duodenum at laparotomy.

The most common type of blunt trauma is a steering-wheel injury. At first, the patient may be asymptomatic, but within a few hours epigastric pain and tenderness supervene. Hyperamylasemia is not a reliable marker of injury, having both a high false-negative and false-positive rate. CT with oral and IV contrast is the preferred diagnostic tool. Postoperative endoscopic retrograde cholangiopancreatography (ERCP) is advisable to assess suspected injury of the pancreatic duct and to stent confirmed injuries. Other tests (eg, ultrasound, peritoneal lavage) have not proved helpful.

Surgery is indicated for all suspected pancreatic injuries; the exact procedure depends on what injury is found at surgery. Contusions without evidence of ductal or duodenal injury are drained widely. If the gland has been completely divided or the duct is disrupted, the portion of the gland distal to the injury is resected. Serious injuries involving the head of the pancreas and the duodenum may require pancreatoduodenectomy or temporary defunctioning of the duodenum as a passage for gastric secretions by closing the pylorus with a temporary suture and emptying the stomach by a gastroenterostomy.

Postoperative complications include abscess, pancreatic or duodenal fistulas, persistent pancreatitis, hemorrhage, and pseudocyst formation.

Pancreatitis

Acute pancreatitis: The major causes in the elderly are alcohol, gallstones, and postoperative inflammation. In elderly patients, gallstones predominate. The mortality rate for acute pancreatitis rises with age--mortality is 6 to 10% for all ages combined.

The patient first notes sudden onset of severe epigastric pain that may radiate to the back or later involve the whole abdomen. Vomiting and epigastric tenderness follow. In severe cases, shock, mild jaundice, and respiratory distress may then develop. Serum amylase levels are elevated early (usually > 1000 U/L) in 95% of cases but may fall thereafter. Serum calcium levels also may fall. Leukocytosis is noted and, if bleeding occurs, Hct is lowered. Hyperglycemia and hypocalcemia are common in severe cases.

Abdominal x-ray sometimes shows a sentinel loop of gas-filled jejunum in the left upper quadrant. Ultrasound is helpful in detecting gallstones but not in evaluating the pancreas; CT is best for evaluating the pancreas.

Differential diagnosis includes perforated peptic ulcer, which may be excluded by endoscopy or by an upper GI series using a diatrizoate meglumine swallow rather than barium. However, strangulating intestinal obstruction or ischemic bowel disease may be more difficult to exclude. Diagnostic laparotomy may be required. Gallstone pancreatitis must also be excluded because it requires surgery. Vascular disease (mesenteric thrombosis or embolism) can lead rapidly to gangrene of the intestine; it mimics acute pancreatitis with pain and leaking toxins.

No laboratory tests can reliably determine the cause of pancreatitis. CT may be helpful and generally shows a relatively normal gland in gallstone pancreatitis and an abnormal gland in severe alcoholic pancreatitis.

Treatment is supportive unless the patient has gallstone pancreatitis. Nasogastric suction, IV alimentation, and fluid replacement are essential. In 85 to 90% of patients, acute pancreatitis is self-limited and conservative measures alone are sufficient. The remainder develop severe disease, resulting in pancreatic necrosis. All patients with severe acute pancreatitis are treated prophylactically with a carbapenem antibiotic (imipenem-cilastatin or meropenem). Those who develop infected necrosis or worsen with nonoperative therapy undergo surgical pancreatic necrosectomy with open or closed drainage. ERCP and endoscopic papillotomy are not used by most surgeons, because there is up to a 20% risk that ERCP will exacerbate preexisting pancreatitis.

The course varies greatly after treatment. Most patients improve rapidly. Patients whose condition worsens require ongoing reevaluations with CT and surgery for the serious complications that can follow.

Chronic pancreatitis: The most severe form of chronic pancreatitis (acute pancreatitis that continues or subsides and recurs) is pancreatolithiasis, in which patients have such severe persistent pain that many become addicted to opioid analgesics. Weight loss, diarrhea caused by loss of enzymes, and diabetes caused by fibrosis of the islets of Langerhans are late complications.

Diagnosis is based on the symptoms and on the secretin test, which is most sensitive. Administration of IV secretin should elicit decreased bicarbonate secretion with or without decreased pancreatic secretions. This test requires ERCP. Other tests that may be helpful are aspartate aminotransferase, lactic dehydrogenase, alkaline phosphatase, serum bilirubin, amylase, glucose, calcium, and phosphate as well as other diagnostic tests--an abdominal x-ray showing pancreatic calcifications is pathognomonic; ERCP and ultrasound can also be helpful.

Surgical treatment consists of pancreaticojejunostomy (anastomosis of a Roux-en-Y loop of the jejunum to the pancreas) when ERCP shows a large, uniformly dilated duct, because obstruction of the ampulla is probable.

Various extirpative procedures may also be required, including distal pancreatectomy when the tail of the gland is involved, Whipple's procedure when only the head is involved, and total pancreatectomy in extreme cases of pancreatolithiasis. Splanchnic nerve resection for pain relief is only occasionally successful. All patients must abstain from alcohol.

Pancreatic Cysts

Several types of cysts occur in the pancreas. Congenital cysts are rare but can be found in some cases of polycystic disease. The gland may contain many small cysts from which cystadenocarcinoma can develop. Excision or resection of a portion of the pancreas may be necessary.

Pseudocysts are initiated by extravasation of pancreatic secretions into the lesser peritoneal sac. The fluid collection evokes a surrounding inflammatory process that promotes formation of a pseudocapsule. Pseudocysts may follow trauma, acute pancreatitis, or chronic pancreatitis. The patient complains of left upper quadrant pain and tenderness, and a mass may be palpable. Diagnosis is usually made by CT. Up to 25% of pseudocysts resolve spontaneously within 6 weeks. The majority persist and may cause pain and obstruction, become infected, or evoke bleeding. Percutaneous drainage with a radiologically guided pigtail catheter is often effective at obliterating a pseudocyst. If this fails or if it is not technically feasible, marsupialization of the cyst to the wall of the stomach or small intestine is the treatment of choice. When considering invasive therapy, the physician should verify that the cyst is at least 6 weeks old to ensure that the wall of the cyst has sufficient structural integrity to hold a drain or retain sutures.