Nadine D. Floyd, M.D., Theodore J. Saclarides, M.D.
1 With regard to C fibers and visceral peritoneal innervation, which of the following statements is true?
A They are myelinated, polymodal nociceptors.
B They travel bilaterally with the sympathetic chains.
C Their stimulation is interpreted as localized, sharp pain.
D They conduct rapidly (<0.5 m/s).
E They refer pain to dermatomes.
Ref.: 1-4
Comments
See Question 2.
Answer
B
2 Which of the following is not a trigger of visceral pain?
A Ischemia
B Traction
C Distention
D Heat
E Inflammation
Ref.: 1-4
Comments
The visceral peritoneum is innervated by C fibers coursing with the autonomic ganglia. C fibers are unmyelinated, slow-conducting (0.5 to 5.0 m/s), polymodal nociceptors that travel bilaterally with the sympathetic and parasympathetic fibers. Visceral pain is a response to injury to the visceral peritoneum. Distention, stretch, traction, compression, torsion, ischemia, and inflammation trigger visceral pain fibers. Abdominal organs are insensate to heat, cutting, and electrical stimulation.
Visceral pain is typically vague and crampy and is perceived in the region of origin of the embryologically derived autonomic ganglia. Foregut organs (proximal to the ligament of Treitz) refer pain to the celiac chain, and the pain is felt in the epigastrium. Inflammation of the gallbladder may be perceived in both the epigastrium and the shoulder; the latter is typical for organs that reside in close proximity to the diaphragms. The organs of the midgut (small intestine and ascending colon) refer pain to the superior mesenteric chain (periumbilical pain) and those of the hindgut (transverse and descending colon, sigmoid colon, and rectum) to the inferior mesenteric ganglia and hypogastrium.
Answer
D
3 An 18-year-old man has a 12-hour history of vague, periumbilical abdominal pain, anorexia, and nonbilious vomiting. The pain has now localized to the right lower quadrant. On examination he is found to have tenderness over the McBurney point along with involuntary muscle rigidity. Which of the following best explains the localization of pain?
A Inflammation of the visceral peritoneum produces localizing pain.
B Pain over the McBurney point is caused by distention of the appendiceal lumen.
C Unmyelinated fibers carry pain signals with the thoracic and lumbar spinal nerves.
D Movement of the inflamed parietal peritoneum induces rebound tenderness.
E The somatic pain fibers course through spinal nerve roots L3-5.
Ref.: 2-5
Comments
Typically, early in the course of appendicitis, distention of the appendiceal lumen triggers the visceral nerves that course with the superior mesenteric artery ganglia and produces vague pain that is perceived in the periumbilical region. As appendiceal inflammation progresses and involves the parietal peritoneum, somatic pain fibers are triggered; these are thinly myelinated, fast-conducting fibers and course with the spinal nerve roots T7-L2. Movement of the inflamed parietal peritoneum will trigger these fibers and is the cause of “rebound tenderness.” Muscle rigidity is involuntary spasm of the abdominal muscles in response to peritoneal inflammation.
Answer
D
4 Which of the following is not an ominous sign in a patient with abdominal pain?
A Diaphoresis
B Pallor
C Hypotension
D Patient lying still
E Jaundice
Ref.: 2-4
Comments
Initial evaluation of patients with acute abdominal pain should include assessment for signs of shock. Shock may be secondary to hypovolemia or a systemic inflammatory response. Signs include tachycardia, hypotension, pallor, dry mucous membranes, poor skin turgor, and slow capillary refill. Immediate intravenous access and resuscitation should be initiated. A patient writhing with colicky pain may have distention or obstruction of a hollow viscus (e.g., ureter or intestine), whereas a patient lying very still probably has diffuse peritoneal inflammation and a perforated viscus. A patient with right upper quadrant pain, fever, jaundice, and signs of septic shock may have ascending cholangitis requiring emergency decompression of the biliary tree. However, jaundice itself is not necessarily an ominous sign.
Answer
E
5 Regarding peritoneal fluids, which of the following statements is true?
A The abdominal cavity normally contains 150 to 200 mL (3 g/dL of isotonic fluid).
B The protein content of peritoneal fluid is 3 g/dL.
C Mesothelial cells absorb solutes via gradient-driven passive osmosis.
D Inflammation of the peritoneum decreases its permeability.
E Bacteria contaminating the peritoneum enter the systemic circulation through the subdiaphragmatic lymphatics.
Ref.: 2
Comments
Normally, the peritoneum contains 50 to 100 mL of fluid, with solute concentrations being equal to those found in plasma. The protein content is less than that of plasma (3 g/dL). Fluid is absorbed by the mesothelial cells lining the peritoneum through endocytosis. Solutes with a molecular weight less than 30 kD are easily absorbed. Inflammation of the peritoneum increases its permeability. Gravity and the negative pressure created by exhalation under the diaphragm effect movement of the peritoneal fluid. The right paracolic gutter allows unhindered movement of fluid from the pelvis to the right subdiaphragmatic area, whereas the phrenicocolic ligaments obstruct flow through the left paracolic gutter. The subdiaphragmatic lymphatics play a major role in the absorption of peritoneal fluid and clearance of solutes and bacteria into the thoracic duct.
Answer
E
6 Which of the following will not alter the natural flow of peritoneal fluid?
A Fibrin
B Bowel obstruction
C Cirrhosis
D Positive pressure ventilation
E Previous appendectomy
Ref.: 2
Comments
Adhesions, fibrin, paralytic ileus, and positive pressure mechanical ventilation all obstruct the normal flux of peritoneal fluid. Adhesions from previous surgery may create compartments within the abdominal cavity that are sequestered from the natural flow of peritoneal fluid. Fluid loss may occur in long-standing bowel obstruction that alters the dynamics of fluid secretion and absorption.
Answer
C
7 Regarding bacterial contamination of the peritoneal cavity, which of the following statements is not true?
A Bacterial contamination of the peritoneum triggers degranulation of mesothelial cells, which initiates the systemic inflammatory response.
B Once the systemic response is initiated, the endothelial cells increase their permeability to complement, opsonins, and fibrin.
C Serum levels of catecholamines decrease in feedback to mast cell degranulation.
D Ninety percent of the bacteria are cleared by phagocytosis and the reticular endothelial system.
E Intraabdominal bacteria enter the systemic circulation through the thoracic duct.
Ref.: 2
Comments
Bacterial contamination triggers mast cells to degranulate, thereby initiating a local and systemic cascade of events. Locally, mesothelial and endothelial cells increase their permeability and allow products of complement, opsonins, and fibrin to enter the peritoneal cavity freely. This increased permeability depletes intravascular volume as fluid shifts into the peritoneal cavity. The systemic inflammatory response syndrome (SIRS) is initiated and consists of an increase in serum levels of catecholamines, glucocorticoids, aldosterone, and vasopressin. The combination of hypovolemia and SIRS causes hyperdynamic hemodynamics. After bacteria enter the abdomen, they circulate via the subdiaphragmatic lymphatics and enter the systemic circulation through the thoracic duct. Once circulating, more than 90% will be cleared by Kupffer cells and the reticuloendothelial system.
Answer
C
8 Regarding the initial assessment of a patient who comes to the emergency department because of acute abdominal pain, which of the following statements is not true?
A Performing thin-cut computed tomographic (CT) scanning with contrast enhancement is the first step in evaluating an acute abdomen.
B Absence of bowel sounds may be seen in cases of mechanical bowel obstruction.
C Hypoactive bowel sounds may suggest an intraabdominal infection.
D Plain radiographic studies can demonstrate abdominal free air, ascites, intraabdominal abscess, and intestinal pneumatosis.
E Ultrasound imaging permits diagnostic and therapeutic treatment of fluid collections.
Ref.: 2
Comments
In a stable patient, a thorough history and physical examination are paramount in determining the potential cause of an acute abdomen and directing the initial work-up; CT scanning is not a substitute for doing so. Distention and high-pitched bowel sounds may represent an early mechanical bowel obstruction. Decreased or absent bowel sounds are suggestive of ileus secondary to an infectious process but may also be found in cases of long-standing obstruction. For a patient with a diffusely rigid abdomen, plain radiographs (upright chest radiograph or lateral decubitus films) may identify free air, which is suggestive of a perforated viscus. Plain radiographs can also demonstrate loculated extraluminal air-fluid levels (e.g., abscess), pneumobilia, portal vein air, pneumatosis intestinalis, or loss of the psoas shadow and fat lines (e.g., ascites). CT and ultrasound imaging can also demonstrate these abnormalities and more accurately characterize intraabdominal fluid or abscess. These modalities may also permit therapeutic percutaneous treatment of fluid collections.
Answer
A
9 A 55-year-old man comes to the emergency department with a 6-hour history of acute, diffuse abdominal pain. On examination, his heart rate is found to be 115 beats per minute, his blood pressure 95/60 mm Hg, his respiratory rate 22 breaths per minute, and his pulse oximetric reading 93% on a 4-L nasal cannula. He has diffuse abdominal rigidity. Plain radiographic studies demonstrate extraluminal free air. Regarding resuscitation of the patient in the emergency department before transfer to the operating room, which of the following statements is true?
A Intravenous administration of antibiotics is the first priority.
B The initial intravenous access of choice is a central venous catheter.
C Two to 3 L of crystalloid should be administered intravenously.
D Endotracheal intubation should be established immediately.
E A CT scan of the abdomen should be ordered immediately
Ref.: 2, 3
Comments
The initial evaluation of a patient with abdominal pain should include assessment for signs of hemodynamic instability, including tachycardia, hypotension, pallor, decreased skin turgor, and decreased urine output. Establishing intravenous access and starting intravenous hydration should be undertaken immediately, and for a patient with hypotension, boluses of crystalloid (lactated Ringer or normal saline solution) should be given. Routine pulmonary artery catheterization is not required unless there is a known history of serious cardiac disease or renal failure. However, if there is no evidence of active bleeding and the blood pressure does not improve after a minimum of 3 L of crystalloid has been infused, cardiac status should be reassessed and central venous pressure measurements considered. Not all patients require mechanical ventilation, but if there is evidence of rapid shallow breathing, impending ventilatory failure (hypercapnia, PaCO2 >50 mm Hg, pH <7.35), or a shunt refractory to oxygen failure (hypoxia, PaO2 <60 mm Hg on an FIO2 of 100%), endotracheal intubation and mechanical ventilation should be established.
Answer
C
10 Regarding patients with a rigid abdomen and free air on plain film, which of the following statements is true?
A No further radiologic work-up is required.
B CT scanning with contrast enhancement is required to confirm the diagnosis.
C Bedside sonographic imaging is preferred over CT imaging to confirm the diagnosis of free air.
D Narcotics are contraindicated in patients with an acute abdomen.
E Preoperative prophylactic steroids are indicated in patients with free air.
Ref.: 2
Comments
For a patient with a rigid abdomen and free air revealed by plain film imaging, no further radiographic work-up is required. Time would be unnecessarily wasted pursuing CT or sonographic imaging in a patient who needs prompt surgical exploration. Narcotics may be given after a patient has been adequately examined, a differential diagnosis established, and a treatment plan instituted. However, caution should be taken in administering narcotics to a hypotensive, incompletely resuscitated patient. There is no role for prophylactic steroid administration except for patients who take steroids chronically and are experiencing abdominal pain or an Addisonian crisis.
Answer
A
11 A 35-year-old woman experiences an acute onset of epigastric and right upper quadrant pain several hours after a large dinner. She has had similar episodes in the past that resolved after a few hours. This episode persists, and she has fever and nonbilious vomiting. What is the most likely source of the abdominal pain?
A Perforated ulcer
B Acute appendicitis
C Perforation following bowel obstruction
D Cholecystitis
E Diverticulitis
Ref.: 2-4
Comments
See Question 15.
Answer
D
12 A 60-year-old man with chronic alcoholism awakens at 3:00 AM with severe, sharp epigastric pain that 3 hours later becomes diffuse abdominal pain. What is the most likely source of the abdominal pain?
A Perforated ulcer
B Acute appendicitis
C Perforation following bowel obstruction
D Cholecystitis
E Diverticulitis
Ref.: 2-4
Comments
See Question 15.
Answer
A
13 A 55-year-old man with a 2-day history of abdominal distention, vomiting, crampy abdominal pain, and obstipation is experiencing severe, diffuse abdominal pain. What is the most likely source of the abdominal pain?
A Perforated ulcer
B Acute appendicitis
C Perforation following bowel obstruction
D Cholecystitis
E Diverticulitis
Ref.: 2-4
Comments
See Question 15.
Answer
C
14 A 22-year-old man awakens with periumbilical abdominal pain followed by nonbilious vomiting. What is the most likely source of the abdominal pain?
A Perforated ulcer
B Acute appendicitis
C Perforation following bowel obstruction
D Cholecystitis
E Diverticulitis
Ref.: 2-4
Comments
See Question 15.
Answer
B
15 A 65-year-old man with a history of chronic constipation has a 3-day history of abdominal distention without a bowel movement. He has fever and abdominal rigidity. What is the most likely source of the abdominal pain?
A Perforated ulcer
B Acute appendicitis
C Perforation following bowel obstruction
D Cholecystitis
E Diverticulitis
Ref.: 2-4
Comments
The examples in Questions 11 to 15 demonstrate the importance of a thorough history in determining a patient’s diagnosis and tailoring the initial work-up in the management of an acute abdomen. Differentiating between patients who require immediate intervention and those who can undergo a more gradual work-up is also essential to avoid unnecessary delays in treatment. Biliary pain is typically midepigastric, with radiation to the right upper quadrant and right subscapular area. It often occurs after the intake of fatty food. It may be intermittent, crampy pain or constant, severe pain associated with nausea and vomiting.
Patients with a perforated ulcer will classically remember the exact moment when the perforation occurred. There may be an initial period of diminished pain followed by severe pain when diffuse chemical peritonitis sets in. Risk factors include a previous history of peptic ulcer disease, untreated Helicobacter pylori infection, use of medications such as steroids and nonsteroidal antiinflammatory drugs, and alcohol abuse.
When vomiting is part of the history, it is important to differentiate between patients with mechanical obstruction of the bowel, bile duct, or pancreatic duct and patients who have ileus in response to problems from a nonintestinal source. A patient with acute appendicitis and periumbilical pain may have one or two episodes of nonbilious emesis before localization of pain in the lower right quadrant. The early abdominal pain and vomiting associated with appendicitis may resemble gastroenteritis. However, in appendicitis, pain is the predominant clinical feature and precedes diarrhea and vomiting in most instances. With gastroenteritis, the vomiting is typically more profuse and frequent and may be accompanied by profuse diarrhea as well.
A history of weight loss or new-onset obstipation and changes in stool patterns may suggest a colorectal malignancy. The duration of time over which these symptoms have developed and progressed may give insight regarding the urgency of the problem. A patient with a 3-day history of progressively obstructive symptoms (i.e., distention, crampy pain, and vomiting) and who has peritonitis and fever is more likely to have a complicated obstruction (e.g., ischemic, gangrenous, or perforated bowel) requiring immediate intervention. If the pain is diffuse, it may herald a free perforation causing diffuse contamination of the peritoneal cavity. If the pain is localized, it may represent a contained perforation, as can occur with diverticulitis. This type of pain typically occurs in the lower left quadrant. In contrast, weight loss, cachexia, a slow decrease in stool caliber, and mild cramping reflect a more gradual process that permits elective work-up and treatment.
Answer
E
16 A 65-year-old man with a history of chronic alcohol abuse has been experiencing epigastric and periumbilical pain associated with nonbilious vomiting for 1 day. He denies any melena or hematemesis. In the past he has had several episodes of similar pain that sometimes radiated to the back, and he was hospitalized for several days 2 months ago. He denies any previous surgery or medical problems. His blood pressure is 120/80 mm Hg, his pulse is 110 beats per minute, and his mucous membranes are dry. His abdomen is not distended and does not have any surgical scars. Bowel sounds are present but diminished. His abdomen is soft, and he exhibits voluntary guarding of the epigastrium. His serum amylase level is 550 units/100 mL. Regarding management of this patient, which of the following is the most reasonable initial step?
A Establish intravenous access.
B Conduct sonographic studies to demonstrate cholelithiasis.
C Perform CT scanning to diagnose a pancreatic pseudocyst.
D Perform esophagogastroduodenoscopy (EGD) to evaluate for varices and complications of cirrhosis.
E Initiate a low-fat diet and antilipid treatment.
Ref.: 2, 6
Comments
A patient with pancreatitis can have severe abdominal pain and rigidity. Surgery should be avoided except for complications (e.g., necrotizing pancreatitis or symptomatic pseudocyst). Initial management of a patient with acute pancreatitis should include bowel rest, intravenous resuscitation, parenteral nutrition, and monitoring in the intensive care unit when appropriate. Causes of pancreatitis should be investigated, including gallstones, hyperlipidemia, and drugs (i.e., thiazides). Alcohol abuse is a common cause of pancreatitis, but the fact that a patient abuses alcohol should not dismiss the necessity for a thorough work-up. After stabilization and resuscitation, diagnostic studies are conducted to define the pancreas and biliary tree. Sonographic studies can screen for stones but may not provide a good evaluation of the retroperitoneum because of overlying bowel gas. CT scanning with contrast enhancement and dedicated fine cuts through the pancreas reveals good pancreatic and retroperitoneal detail in most patients.
For patients with recurrent or chronic pancreatitis, a CT scan should be performed to look for complications of pancreatitis, such as a pancreatic pseudocyst, fistula, or mass. EGD is not generally used to make the diagnosis of pancreatitis. It may be a useful adjunctive diagnostic and potentially therapeutic tool during the evaluation of alcoholic patients experiencing upper gastrointestinal bleeding.
Answer
A
17 A patient with known diverticular disease of the colon has a 5-day history of worsening pain in the left lower quadrant. He now has fever and had diarrhea this morning. On examination he is found to have fullness in the lower left quadrant with guarding. What would the best management now include?
A Diagnostic laparoscopy
B Immediate operative exploration
C Air-contrast enema
D Colonoscopy
E CT scan of the abdomen and pelvis
Ref.: 2, 7
Comments
In complicated cases, such as those involving fever, a mass, localized peritonitis, and leukocytosis, hospitalization with bowel rest, broad-spectrum intravenous antibiotics, and serial examinations should be initiated. CT scanning should be performed to differentiate cases of diverticulitis from phlegmon and abscess. The latter can be drained percutaneously. Elective resection and primary anastomosis can then be undertaken following successful nonoperative treatment of an abscess and after the inflammation has subsided. A patient who becomes hemodynamically unstable during a period of conservative management or does not improve with nonoperative measures will require prompt surgical exploration. In this setting, resection of the diseased segment is generally preferred, but the surgeon may elect to perform fecal diversion and drainage if the phlegmon is adherent and resection is too dangerous. Resection is more effective in treating the sepsis and reduces the number of operations needed to resolve the problem.
Answer
E
18 A 55-year-old man comes to the physician’s office with complaints of left lower quadrant abdominal pain. He reports chronic constipation but denies any nausea or vomiting. He denies melena or bright red blood, fever, or anorexia. On examination, his abdomen is not found to be distended and exhibits no surgical scars. He has mild tenderness in the left lower quadrant without guarding. Of the following, which is the best management?
A Administer oral antibiotics and prescribe a clear liquid diet.
B Immediately conduct operative exploration.
C Begin bowel preparation for colonoscopy.
D Administer an air-contrast barium enema.
E Perform a CT scan of the abdomen.
Ref.: 2, 7
Comments
Diverticulitis is a common source of abdominal pain that often does not require immediate intervention. Mild cases without evidence of peritonitis, fever, or leukocytosis can be treated on an outpatient basis with oral antibiotics. However, it is important to have a reliable and compliant patient who will return if worsening pain or fever develops. Once the episode subsides, a work-up, including colonoscopy or a barium enema (or both), should be performed to confirm evidence of diverticulosis and to rule out malignancy. However, these tests should not be performed during an acute exacerbation since the instrumentation and distention of the inflamed bowel entail a higher risk for perforation. CT scans of the abdomen are indicated for complicated cases (fever, leukocytosis, localized peritonitis) either at initial evaluation or if no improvement is seen within a short period.
Answer
A
19 Regarding peritonitis, which of the following statements is not true?
A Primary peritonitis is more common in children with nephrosis and adults with cirrhosis than in patients without such conditions.
B Primary peritonitis is usually monomicrobial.
C Chemical peritonitis often precedes bacterial contamination.
D Multiple organisms are commonly cultured from peritoneal dialysis catheters.
E Tuberculous peritonitis has an insidious onset.
Ref.: 2
Comments
Primary, or spontaneous, peritonitis occurs in the absence of a known intraabdominal source. It is seen more often in children, and single microbes are isolated. The most commonly cultured organisms include pneumococcus and hemolytic streptococci. Among adults, patients with cirrhosis and ascites and those managed with peritoneal dialysis are at higher risk, and Escherichia coli and Klebsiella are more commonly cultured. Secondary peritonitis is more frequently encountered by the surgeon and implies inflammation secondary to a known intraabdominal source (e.g., perforated viscus). Chemical peritonitis is most commonly caused by sterile body fluids, including gastric contents, bile, urine, pancreatic fluid, and blood. Chemical peritonitis is often followed by bacterial contamination, as in the case of perforated peptic ulcer.
Patients with chronic peritoneal dialysis catheters are prone to peritonitis. These infections are monomicrobial and may respond to intraperitoneal and systemic antibiotics. If multiple organisms are grown from peritoneal fluid cultures, intestinal perforation should be suspected. Tuberculous peritonitis usually occurs in chronically ill or malnourished patients and may accompany pulmonary reactivation. Its onset is generally insidious, with several weeks of fever, weight loss, anorexia, ascites, and dull, diffuse abdominal pain.
Answer
D
References
1 Tavakkolizadeh A, Whang EE, Ashley SW, et al. Small intestine. In Brunicardi FC, Andersen DK, Billiar TR, et al, editors: Schwartz’s principles of surgery, ed 9, New York: McGraw-Hill, 2010.
2 Postier RG, Squires RA. Acute abdomen. In Townsend CM, Beauchamp RD, Evers BM, et al, editors: Sabiston textbook of surgery: the biological basis of modern surgical practice, ed 18, Philadelphia: WB Saunders, 2008.
3 Silen W, editor. Cope’s early diagnosis of the acute abdomen, ed 19, New York: Oxford University Press, 1996.
4 Martin RF, Rossi RL. The acute abdomen: an overview and algorithms. Surg Clin North Am. 1997;77:1227-1243.
5 Jaffe BM, Berger DH. The appendix. In Brunicardi FC, Andersen DK, Billiar TR, et al, editors: Schwartz’s principles of surgery, ed 9, New York: McGraw-Hill, 2010.
6 Fisher WE, Andersen DK, Bell RH, et al. Pancreas. In Brunicardi FC, Andersen DK, Billiar TR, et al, editors: Schwartz’s principles of surgery, ed 9, New York: McGraw-Hill, 2010.
7 Bullard Dunn KM, Rothenberger DA. Colon, rectum and anus. In Brunicardi FC, Andersen DK, Billiar TR, et al, editors: Schwartz’s principles of surgery, ed 9, New York: McGraw-Hill, 2010.