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USMLE Step 2 CK λ Surgery

before proceeding to exploration. These include myocardial ischemia (obtain an ECG), lower lobe pneumonia (perform a chest x-ray), PE (suspect in an immobilized patient), and abdominal processes that do not require surgical exploration, such as pancreatitis (check serum amylase and lipase) and urinary stones (perform a non-contrast CT scan of abdomen).

Acute pancreatitis should be suspected in the alcoholic who develops an “upper” acute abdomen. The classic picture has rapid onset for an inflammatory process (a few of hours), and the pain is constant, epigastric, radiating straight through to the back, with nausea, vomiting, and retching. Physical findings are relatively modest, found in the upper abdomen. Diagnose with serum amylase and lipase, CT if diagnosis is not clear. Treat with NPO, NG suction, IV fluids. (More details in pancreatic disease section.)

Biliary tract disease should be suspected in the obese multiparrous female patient ages 30-50 (“fat, female, forty, fertile”) who presents with right upper quadrant abdominal pain.

Ureteral stones produce sudden onset colicky flank pain radiating to inner thigh and scrotum or labia, sometimes with urinary symptoms like urgency and frequency; and with microhematuria discovered on urinalysis. Non-contrast CT scan is the best diagnostic test.

Acute diverticulitis is one of the very few inflammatory processes giving acute abdominal pain in the left lower quadrant (in women, the fallopian tube and ovary are other potential sources).

•Patients are typically middle-aged and present with fever, leukocytosis, physical findings of peritoneal irritation in the left lower quadrant, occasionally with a palpable tender mass.

•CT scan with oral and IV contrast is diagnostic.

•Treatment is NPO, IV fluids, and antibiotics.

•Most will cool down.

•Emergency surgery is needed for those who do not demonstrate evidence of free perforation of fistulization (most often to the bladder, presenting with pneumaturia).

•Radiologically guided percutaneous drainage of an abscess may be helpful and help prevent emergent surgical resection but if successful, usually will require elective resection.

•Colonoscopy is indicated around 6 weeks after an episode of diverticulitis to rule out an underlying malignancy (endoscopy earlier in the presence of active inflammation increases the likelihood of perforation and decreases the diagnostic sensitivity).

•Elective resection of the involved colon is indicated for those who have had complications, multiple attacks, or continuing discomfort.

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Copyright 2007 Bates, M.D. - Custom Medical Stock Photo.

Figure I-4-2. Abdominal CT scan of 56-year-old Man with

Acute Diverticulitis of Sigmoid Colon

Volvulus of the sigmoid is seen in older patients. It presents with signs of intestinal obstruction and severe abdominal distention. X-rays are diagnostic, as they show air-fluid levels in the small bowel, very distended colon, and a huge air-filled loop in the right upper quadrant that tapers down toward the left lower quadrant with the shape of a “parrot’s beak.”

Proctosigmoidoscopic exam resolves the acute problem and asses for mucosal ischemia; leaving a rectal tube allows for complete decompression and prevents immediate recurrence. Recurrent cases need elective sigmoid resection.

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USMLE Step 2 CK λ Surgery

Mesenteric ischemia is also seen predominantly in the elderly, but the real key is the development of an acute abdomen in someone with atrial fibrillation or a recent MI (the source of the clot that breaks off and lodges in the superior mesenteric artery). Because the very old do not mount impressive acute abdomens, often the diagnosis is made late, when there is blood in the bowel lumen (the only condition that mixes acute pain with GI bleeding), and lactic acidosis and sepsis have developed. In very early cases, arteriogram and embolectomy might save the day, whereas once bowel ischemia is present, surgical resection is mandatory.

Hepatobiliary

Liver

Primary hepatoma (hepatocellular carcinoma) is seen in the United States in patients with cirrhosis. Patients develop vague right upper quadrant discomfort and weight loss. The specific blood marker is α-fetoprotein (AFP). CT scan will show location and extent. Resection is done if technically possible.

Metastatic cancer to the liver outnumbers primary cancer of the liver in the United States by 20:1. It is found by CT scan if follow-up for the treated primary tumor is under way, or suspected because of rising carcinoembryonic antigen (CEA) in those who had colonic cancer. If the primary is slow growing and the metastases are confined to one lobe, resection can be done. Other means of control include radiofrequency ablation (RFA).

Hepatic adenoma may arise as a complication of birth control pills, and is important because it has a tendency to rupture and bleed massively inside the abdomen. CT scan is diagnostic. If symptomatic, oral contraceptives should be stopped immediately; emergency surgery is required for patients presenting with signs of rupture and massive hemorrhage. Patients may not resume birth control pills.

Pyogenic liver abscess is seen most often as a complication of biliary tract disease, particularly acute ascending cholangitis. Patients develop fever, leukocytosis, and a tender liver. Sonogram or CT scan are diagnostic. Percutaneous drainage is required.

Amebic abscess of the liver favors men, all of whom have a “Mexico connection.” (It is very common there, and seen in the U.S in immigrants.) Presentation and imaging diagnosis are similar to pyogenic liver abscesses, but can be treated with Metronidazole and rarely require drainage. Definitive diagnosis is maden by serology (the ameba does not grow in the pus), but because the test takes weeks to be reported, empiric treatment is started in those clinically suspected. If they improve, it is continued; if not, drainage is indicated.

Jaundice

Jaundice may be hemolytic, hepatocellular, or obstructive.

•Hemolytic jaundice is usually low level (bilirubin of 6-8 mg/dL, but not 35 or 40), and all the elevated bilirubin is unconjugated (indirect), with no elevation of the conjugated (direct) fraction. There is no bile in the urine. Workup should determine what is chewing up the red cells.

•Hepatocellular jaundice has elevation of both fractions of bilirubin, and very high levels of transaminases with only a modest elevation of the alkaline phosphatase. Hepatitis is the most common example, and workup should proceed in that direction (serologies to determine specific type).

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•Obstructive jaundice has elevations of both fractions of bilirubin, modest elevation of transaminases, and very high levels of alkaline phosphatase. The first step in the workup is an U/S looking for dilatation of the biliary ducts, as well as further clues as to the nature of the obstructive process. In obstruction caused by stones, the stone that is obstructing the common duct is seldom seen, but stones are seen in the gallbladder, which because of chronic irritation cannot dilate. In malignant obstruction, a large, thin-walled, distended gallbladder is often identified (Courvoisier-Terrier sign).

––Obstructive jaundice caused by stones should be suspected in the obese, fecund woman in her forties, who has high alkaline phosphatase, dilated ducts on sonogram, and nondilated gallbladder full of stones. The next step in that case is an endoscopic retrograde cholangiopancreatography (ERCP) to confirm the diagnosis, perform a sphincterotomy, and remove the common duct stone. Cholecystectomy should usually follow during the same hospitalization.

––Obstructive jaundice caused by a tumor could be caused by adenocarcinoma of the head of the pancreas, adenocarcinoma of the ampulla of Vater, or cholangiocarcinoma arising in the common duct itself.

ººOnce a tumor has been suspected by the presence of dilated gallbladder in the sonogram, the next test should be CT scan. Pancreatic cancers that have produced obstructive jaundice are often big enough to be seen on CT. If the CT is negative, ERCP is the next step.

ººAmpullary cancers or cancers of the common duct by virtue of their strategic location produce obstruction when they are still very small, and therefore may not be seen on CT, but endoscopy will show ampullary cancers and the cholangiography will show intrinsic tumors arising from the duct (apple core) or small pancreatic cancers.

ººThe recent advent of endoscopic U/S has given us another diagnostic pathway to locate and biopsy these tumors. Percutaneous biopsy is not indicated to avoid seeding the abdominal wall with tumor; if cancer is suspected and a tumor is identified on CT or ERCP, it should be resected if no contraindications are present (i.e. evidence of metastatic disease).

Ampullary cancer should be suspected when malignant obstructive jaundice coincides with anemia and positive blood in the stools.

•Can bleed into the lumen like any other mucosal malignancy, at the same time that it can obstruct biliary flow by virtue of its location.

•Given that combination, endoscopy should be the first test.

Pancreatic cancer is seldom cured, even when resectable by the Whipple operation (pancreatoduodenectomy).

Ampullary cancer and cancer of the lower end of the common duct have a much better prognosis (about 40% cure).

Gallbladder

Gallstones are responsible for the vast majority of biliary tract pathology. There is a spectrum of biliary disease caused by gallstones, as noted below. Although the obese woman in her forties is the “textbook” victim, incidence increases with age so that eventually they are common across all ethnic groups. Asymptomatic gallstones are left alone.

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Acute ascending cholangitis is a far more deadly disease, in which stones have reached the common duct producing partial obstruction and ascending infection.

•Patients are often older and much sicker.

•Temperature spikes to 104–105°F, with chills, and very high white blood cell count indicating sepsis.

•There is some hyperbilirubinemia but the key finding is extremely high levels of alkaline phosphatase.

•Charcot’s triad is the presence of fever, jaundice, and right upper quadrant pain and is suggestive of ascending cholangitis; Reynolds pentad is those 3 symptoms plus altered mental status and evidence of sepsis (most commonly, hypotension), which further suggests the diagnosis.

•IV antibiotics and emergency decompression of the common duct is lifesaving; this is performed ideally by ERCP, alternatively percutaneous through the liver by percutaneous transhepatic cholangiogram (PTC), or rarely by surgery.

•Eventually cholecystectomy has to be performed.

Obstructive jaundice without ascending cholangitis can occur when stones produce complete biliary obstruction, rather than partial obstruction. Presentation and management were detailed in the jaundice section.

Biliary pancreatitis is seen when stones become impacted distally in the ampulla, temporarily obstructing both pancreatic and biliary ducts. The stones often pass spontaneously, producing a mild and transitory episode of cholangitis along with the classic manifestations of pancreatitis (elevated amylase or lipase). U/S confirms gallstones in the gallbladder. Medical management

(NPO, NG suction, IV fluids) usually leads to improvement, allowing elective cholecystectomy to be done later. If not, ERCP and sphincterotomy may be required to dislodge the impacted stone.

Pancreas

Acute pancreatitis is seen as a complication of gallstones (as described above), or in alcoholics. Acute pancreatitis may be edematous, hemorrhagic, or suppurative (pancreatic abscess). Late complications include pancreatic pseudocyst and chronic pancreatitis.

Reproduced with permission from VGHTC,

Gastroenterology Section.

Figure I-4-5. Grey-Turner Sign Can Be

seen in Acute Pancreatitis

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USMLE Step 2 CK λ Surgery

Acute edematous pancreatitis occurs in the alcoholic or the patient with gallstones. Epigastric and midabdominal pain starts after a heavy meal or bout of alcoholic intake, is constant, radiates straight through to the back, and is accompanied by nausea, vomiting, and (after the stomach is empty) continued retching. There is tenderness and mild rebound in the upper abdomen. Serum amylase and lipase are elevated, and often serum hematocrit levels are high due hypovolemia. Resolution usually follows a few days of pancreatic rest (NPO, NG suction, IV fluids).

Acute severe pancreatitis is a much more deadly disease. It starts as the edematous form does, but an early lab clue is lower hematocrit (the degree of amylase elevation does not correlate with the severity of the disease). Other findings have been catalogued (Ranson’s criteria):

•At the time of presentation, elevated WBC count, elevated blood glucose, and low serum calcium

•By the next morning, hematocrit is even lower, continued low serum calcium (in spite of calcium administration), increased blood urea nitrogen, and eventual metabolic acidosis and low arterial PO2

Prognosis at that time is terrible, and intensive supportive therapy is needed in the ICU. This includes significant IV fluid hydration, possibly mechanical ventilation, and enteral feeding (distal to the pancreas). A common final pathway for death is the development of multiple pancreatic abscesses; try to anticipate them and drain if possible. If drained fluid is positive for bacteria (often gram-negative), the antibiotic of choice is IV carbopenem (imipenem or meropenem).

Necrosectomy is the best way to deal with necrotic pancreas, but timing is crucial. Most practitioners will wait as long as possible before necrosectomy is offered, as it requires the dead tissue to delineate well and mature for dissection. Patients do far better by waiting at least 4 weeks before debridement of the dead pancreatic tissue. Many pancreatic abscesses are not amenable to percutaneous or open drainage and will require open drainage or debridement.

Pancreatic abscess (acute suppurative pancreatitis) may become evident in someone who was not getting CT scans, because persistent fever and leukocytosis develop ~10 days after the onset of pancreatitis and sepsis develops. Imaging studies done at that time will reveal the collection(s) of pus, and percutaneous drainage and imipenem or meropenem will be indicated.

Pancreatic pseudocyst can be a late sequela of acute pancreatitis, or of pancreatic (upper abdominal) trauma. In either case, ~5 weeks elapses between the original problem and the discovery of the pseudocyst. There is a collection of pancreatic juice outside the pancreatic ducts (most commonly in the lesser sac), and the pressure symptoms thereof (early satiety, vague symptoms, discomfort, a deep palpable mass). CT or U/S will be diagnostic. Treatment is dictated by the size and age of the pseudocyst.

•Cysts ≤6 cm or those that have been present <6 weeks are not likely to have complications and can be observed for spontaneous resolution.

•Larger (>6 cm) or older cysts (>6 weeks) are more likely to cause obstruction, bleed, or infection, and they need to be treated.

Treatment involves drainage of the cyst. The cyst can be drained percutaneously to the outside, drained surgically into the GI tract, or drained endoscopically into the stomach.

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Chapter 4 λ General Surgery

Chronic pancreatitis is a devastating disease. People who have repeated episodes of pancreatitis (usually alcoholic) eventually develop calcified burned-out pancreas, steatorrhea, diabetes, and constant epigastric pain. The diabetes and steatorrhea can be controlled with insulin and pancreatic enzymes, but the pain is resistant to most modalities of therapy and can be incredibly debilitating. If ERCP shows specific points of obstruction and dilatation, operations that drain the pancreatic duct may help.

Hernias

All abdominal hernias should be electively repaired to avoid the risk of intestinal obstruction and strangulation. Exceptions include:

•Asymptomatic umbilical hernia in patients age <5 (they typically close spontaneously)

•Esophageal sliding hiatal hernias (not “true” hernias)

Hernias that become irreducible need emergency surgery to prevent strangulation. Those that have been irreducible for years need elective repair.

Figure I-4-6. Gross Appearance of Large Umbilical Hernia

DISEASES OF THE BREAST

In all breast disease, cancer must be ruled out even if the presentation suggests benign disease. The only sure way to rule out cancer is to get tissue for the pathologist. Age correlates best with the odds for cancer:

•Virtually unknown in the teens

•Rare in young women

•Quite possible by middle age

•Very likely in the elderly

Women with family history are at risk from an earlier age.

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