Acute Abdomen and Common Surgical Abdominal Problems

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[edit] Acute Abdomen and Common Surgical Abdominal Problems

Eric S. Lambright

Noel N. Williams

The patient with acute abdominal pain offers a diagnostic challenge to the physician because of the wide spectrum of disease processes that present with this symptom. Abdominal pain can represent processes as varied as a benign, self-limited viral gastroenteritis to a perforated hollow viscus that is uniformly fatal without intervention. As with all other acute disease processes, accurate diagnostic evaluation and prompt implementation of definitive therapy are essential. The diagnostic evaluation of acute abdominal pain requires a focused and precise history, complete physical examination, and appropriate complementary radiographic and laboratory studies.

[edit] PATIENT EVALUATION

[edit] History

The diagnosis of processes causing acute abdominal pain can often be made by the history alone. The symptom of pain must be precisely defined. Other symptoms helpful in the evaluation of acute abdominal pain include vomiting, anorexia, changes in bowel habit, and in females the time in the menstrual cycle.

[edit] Pain.

Knowledge of physiology and anatomy should be applied to mediators of visceral pain and location of intraperitoneal organs. Abdominal pain is mediated by the autonomic nervous system and the intercostal nerves from the fifth to eleventh spinal cord segments. The autonomic response to pain is poorly localized, reported as “deep,” and associated with systemic responses such as diaphoresis, nausea, tachycardia, and decrease in blood pressure. Chemical irritation, mechanical stimulation, contraction against resistance, or sudden distention will stimulate afferent visceral nerve fibers and cause pain. In contrast to viscerally mediated symptoms, irritation of the parietal peritoneum causes a more localized sharp pain, and the resultant abdominal tenderness and rigidity can be elicited on physical examination. This duality of abdominal pain is exemplified by the pain of acute appendicitis, which classically begins as a viscerally mediated, periumbilical dull ache that “migrates” to the right lower quadrant as the parietal peritoneum becomes progressively inflamed. Pain from intraperitoneal viscera may occur at sites distant from the abdomen. This referred pain has significant clinical implications, as exemplified by the pain felt at the tip of the scapulae from acute cholecystitis or the shoulder pain experienced with diaphragm irritation.

The symptom of pain must be precisely characterized as to onset, duration, character, and radiation. Pain that begins suddenly in a previously well patient suggests a perforated hollow viscus, a vascular catastrophe, or acute pancreatitis. Pain of severe intensity that began acutely and lasts longer than 6 hours is often associated with a surgical disease process. In contrast, progressive pain may reflect a worsening intraperitoneal inflammatory process (e.g., diverticulitis, cholecystitis, appendicitis) or may indicate intestinal obstruction. The character of the pain is helpful in the diagnostic evaluation: the “burning” of a perforated ulcer, the “tearing” of an aortic dissection, or the “crampy” pain of intestinal obstruction. The radiation of pain can also be helpful. Classically, in biliary system processes, pain will radiate to the scapulae; in ureteral processes, to the groin; inflammation of the pancreas, to the back; and diaphragm irritation, to the shoulder.

[edit] Emesis.

The patient with an acute abdomen often complains of vomiting. In acute abdominal processes, vomiting is caused by acute gastric irritation, severe visceral afferent nerve irritation, or obstruction of an involuntary muscular tube (e.g., bowel, biliary duct, ureter, appendix). The frequency and the character of the vomitus should be characterized. Frequent, scanty emesis is associated with pancreatitis, in contrast to the intermittent, voluminous emesis seen in a distal small bowel obstruction. The absence of vomiting, however, does not rule out an intraabdominal catastrophe.

[edit] Bowels.

A change in a patient's bowel habits is often associated with an acute intraabdominal process. Obstipation (an absence of the passage of gas or stool) is often indicative of intestinal obstruction. Melena or occult blood in the stool may reflect underlying ulcer disease or malignancy. Diarrhea is sufficiently common that it provides little specific information in the diagnostic workup. Tenesmus often reflects pelvic inflammatory disease, pelvic appendicitis, or ectopic pregnancy with hemorrhage and may indicate inflammatory bowel disease.

A review of systems must also be included in a thorough history. The physician should obtain a surgical history and determine if the patient ever had the symptoms. Extraabdominal disease processes also may be present with abdominal pain, such as atypical angina, diabetic ketoacidosis, sickle cell crisis, or pyelonephritis. The patient's physiologic reserve is assessed for any underlying cardiac, pulmonary, endocrine, or renal disease that may complicate medical or surgical management.

[edit] Physical Examination

Examination of the patient provides further data to support the preliminary diagnosis established by a thorough history. During the abdominal examination the physician should “think anatomically” and apply relationships between intraabdominal structures. For example, pain localizing to the right upper quadrant may be caused by the liver, biliary system including gallbladder, duodenum, hepatic flexure, or right kidney (Box 107-1).

The examination begins with the patient's general appearance. A patient with an acute inflammatory process in the abdomen causing peritonitis remains still and shows obvious pain with any movement. In contrast, the patient with intestinal obstruction or ureteral stone is restless and has intermittent episodes of agony. A patient's vital signs are nonspecific but helpful in defining physiologic stability.

[edit] Vital Signs.

The patient with acute abdominal disease may be febrile, normothermic, or hypothermic. High fever (greater than 104° F [40° C]) is suggestive of renal, biliary, or pulmonary sepsis. A low-grade fever (100° to 101.5° F [37.7° to 38.5° C]) is consistent with most abdominal inflammatory processes, such as appendicitis, diverticulitis, cholecystitis, or pancreatitis. A normal temperature does not rule out intraabdominal disease and is often seen in the early stages of ulcer perforation. Hypothermia suggests severe sepsis and is a poor prognostic indicator. The pulse rate, blood pressure, and respiratory rate are nonspecific indicators as well. Tachycardia may reflect hemorrhage or hypovolemia related to “third space” fluid accumulation or vomiting. Cardiovascular collapse associated with acute abdominal pain indicates intraabdominal hemorrhage and requires aggressive surgical therapy. Tachypnea may reflect a primary intrathoracic process or may be a physiologic response to a metabolic acidosis secondary to an abdominal process.

[edit] Abdominal Examination.

A general inspection of the abdomen can identify areas of abnormal distention or surgical scars, with specific attention to areas of potential hernia formation. Findings on abdominal auscultation are nonspecific. Any inflammatory process within the abdomen may cause a paralytic ileus, and examination reveals a “quiet” abdomen. Hyperactive bowel sounds can be found in intestinal obstruction but are also heard in viral gastroenteritis. It is dangerous to dismiss the presence of an acute abdominal process because “the patient had normal bowel sounds.”

Palpation and percussion of the patient with abdominal pain require gentleness and should proceed from areas of least to most pain. Percussion may demonstrate abnormal areas of dullness consistent with fluid or areas of increased tympany, which reflects an air-filled viscus or, when demonstrated over the liver, often signifies pneumoperitoneum. Gentle percussion also may demonstrate areas of “rebound” tenderness and more accurately localize an area of peritoneal inflammation. Palpation of the abdomen can localize tenderness, identify any unique masses within the abdomen, or determine the presence of swelling from a hernia and the extent of muscle rigidity. Deep palpation over the abdomen with sudden release can produce “rebound” tenderness in almost all patients, and gentle palpation or percussion of the abdomen can elicit more useful diagnostic information.

In addition to examination of the main abdominal cavity, digital rectal examination is important and informative. Rectal masses such as tumors, stool, or strictures can be identified. The pelvic peritoneum can be examined for areas of local tenderness or masses. Tenderness laterally to the right is consistent with acute appendicitis and intussusception, whereas tenderness laterally to the left may reflect diverticulitis and possible abscess. In females a bimanual examination can identify an adnexal mass that may reflect an abscess, ovarian mass, or ectopic pregnancy. The stool is examined for gross blood or melena and tested for occult blood.

[edit] LABORATORY STUDIES AND DIAGNOSTIC PROCEDURES

A thorough history and physical examination can provide an accurate diagnosis in two thirds of patients with acute abdominal pain. Laboratory and radiographic evaluation can supplement the clinical examination and assist in preoperative preparation. Tests should only be performed, however, if the results would alter patient management.

Blood should be drawn for laboratory analysis and cross-matching performed in most patients with acute abdominal pain. A complete blood cell count (CBC) with differential is useful but never diagnostic. A rising or significant leukocytosis supports the diagnosis of an acute infectious or inflammatory process. Anemia may reflect acute or chronic blood loss and often requires correction before surgical intervention. An electrolyte panel is important, especially in the patient who requires hydration or who has had significant fluid shifts. Arterial blood gases should be obtained in critically ill patients or those with significant underlying cardiopulmonary disease. A metabolic acidosis often reflects a serious intraabdominal process. Liver function tests and pancreatic enzymes should be obtained when hepatobiliary disease is suspected. Prothrombin time (PT) and partial thromboplastin time (PTT) are necessary when surgery is planned. Urinalysis may reveal hematuria or pyuria consistent with a urologic process, and specific gravity measurement reflects hydration status. Stool studies should be performed in patients with a suspected infectious process (e.g., Clostridium difficile colitis) but are rarely helpful in the acute setting.

[edit] Radiographic Evaluation

An upright chest film is essential in evaluating the patient with acute abdominal pain. It may reveal thoracic pathology that has presented with intraabdominal symptoms or free intraperitoneal air under the diaphragm. A film is also vital to the preoperative assessment. Plain radiographs of the abdomen (flat plate and upright views) are useful in the patient with suspected intestinal obstruction but are often not helpful and should be used selectively. An abdominal series may reveal an abnormal bowel gas pattern, free air, pneumatosis (air in the bowel wall), or pneumobilia (air in the biliary system); suggest an intraabdominal mass lesion; or define radiopaque densities such as renal or biliary calculi.

In patients with acute abdominal pain a computed tomography (CT) scan of the abdomen is most useful in evaluating the organs of the retroperitoneum or assessing localized infections. CT is helpful in the management of patients with pancreatitis and diverticulitis and may be useful in the evaluation of appendicitis when the diagnosis is unclear. An abdominal CT scan should be used selectively in patients with acute abdominal pain and may provide confusing information if an adequate history and physical examination were not performed.

Ultrasonography is useful in evaluating the hepatobiliary tree and gallbladder, assessing intraabdominal masses, and studying the adnexal structures. Ultrasound can identify gallstones, pericholecystic fluid, and common bile duct dilation. Ultrasound also should be used selectively.

Angiography is indicated in the patient with acute abdominal pain if intestinal ischemia is suspected. Mesenteric infarction may be revealed by visceral arteriography. Angiography has no role in the patient with suspected ruptured abdominal aortic aneurysm except at centers where endovascular aortic tube grafts are a possible therapeutic option.

Gastrointestinal contrast studies should not be used as initial tests in the evaluation of acute abdominal pain. A water-soluble contrast study may be useful in the patient with suspected ulcer perforation without free air on plain films. A limited barium enema can identify the lesion causing large bowel obstruction. A radionuclide excretion study using technetium-labeled derivatives of iminodiacetic acid (HIDA) to image the biliary ductal system and gallbladder may be used to complement ultrasound in the evaluation of acute cholecystitis. Gallium scans are useful to identify abscesses. These studies have little utility, however, in the initial evaluation of acute abdominal pain.

[edit] SPECIFIC DISEASE PROCESSES

[edit] Peptic Ulcer Disease

Free perforation of a peptic ulcer is always fatal if untreated, emphasizing the need for early diagnosis and treatment. Perforation and the resultant spillage of acidic secretions cause sudden epigastric burning pain. Early symptoms are marked by generalized pain that often radiates to the shoulders, with associated nausea. Initially the patient is diaphoretic and tachycardic and appears unwell. After the initial perforation the patient may show clinical improvement over several hours; the pain may subside, vomiting may cease, and general appearance may improve. However, the physical examination confirms abdominal tenderness with abdominal wall rigidity but without significant distention, decreased liver dullness, and severe pain with any movement. Subsequently, within 12 to 24 hours the patient shows signs of severe peritonitis with abdominal distention and hypotension and tachycardia from hypovolemic shock. At this point the pathologic process is probably irreversible, and death is imminent.

The diagnosis of ulcer perforation is relatively easy based on a thorough history and physical examination. A history of chronic indigestion or known ulcer disease may be obtained. A sudden onset of burning epigastric pain with evidence of peritonitis on physical examination is most consistent with ulcer perforation. An upright plain radiograph of the chest may often be diagnostic of pneumoperitoneum (Fig. 107-1); however, free air is not seen on plain radiographs in approximately 30% of patients with ulcer perforation.^[1] An abdominal CT scan may be helpful when plain radiographs are nondiagnostic but the history and physical examination are consistent with the diagnosis. Treatment requires restoration of intravascular volume, antibiotics, nasogastric decompression, and surgical exploration with definitive treatment of the perforation.

Figure 107-1 Upright chest radiograph reveals free intraperitoneal air under right hemidiaphragm in patient with perforated duodenal ulcer.

[edit] Hepatobiliary Tract

[edit] Acute Cholecystitis.

Inflammation of the gallbladder is a common cause of acute abdominal pain. Acute cholecystitis is linked to the presence of gallstones and is a result of cystic duct occlusion by a stone impacted in Hartmann's pouch. Classically, this disease process affects middle-age women who are overweight. Typically, pain in the right upper quadrant is associated with nausea and emesis, often with a history of intermittent, vague, postprandial abdominal discomfort. Physical examination reveals fever (usually low grade) and tenderness in the right upper quadrant, scleral icterus may be present, and a palpable inflammatory mass is occasionally appreciated. Leukocytosis and hyperbilirubinemia are often present, although a greatly elevated bilirubin level is more suggestive of choledocholithiasis. Ultrasonography can confirm the diagnosis and determine the presence of gallstones, evaluate for thickening of the gallbladder wall or pericholecystic fluid, and measure the size of the common bile duct (Fig. 107-2). If the diagnosis is still unclear, a nuclear medicine study with cholescintigraphy (HIDA scan) can confirm acute cholecystitis if gallbladder filling is absent. Therapy for uncomplicated acute cholecystitis is hydration, bowel rest, antibiotics, analgesia, and after stabilization, cholecystectomy.

Figure 107-2 Right upper quadrant ultrasound reveals gallstones in patient with symptoms of biliary colic.

[edit] Cholangitis.

Cholangitis is an imminently life-threatening disease process characterized by the classic symptoms of fever, jaundice, and right upper quadrant abdominal pain (Charcot's triad). Cholangitis results from obstruction of the biliary system from choledocholithiasis or from a bile duct stricture secondary to malignancy or previous surgery. This results in a buildup of purulence within the biliary ductal system and ascending infection of the liver. The patient with cholangitis is acutely ill, jaundiced, pyrexic, and hypotensive and has significant right upper abdominal tenderness, often with a history of gallstones or previous biliary surgery. Laboratory evaluation reveals leukocytosis, hyperbilirubinemia, and electrolyte abnormalities consistent with hypovolemia. Therapy requires aggressive resuscitation, antibiotics, and surgical decompression of the biliary system. Decompression can be achieved by endoscopic methods to retrieve obstructing gallstones. A sphincteroplasty can also be performed endoscopically to improve drainage through the sphincter of Oddi. Decompression may be performed by percutaneously draining a dilated biliary system retrograde through the liver under ultrasound guidance. Open surgical drainage is required if these interventions are not successful.

[edit] Acute Pancreatitis.

An extremely painful and potentially life-threatening disease process, acute pancreatitis is diagnosed by the history and physical examination. A history of untreated cholelithiasis or a recent alcohol binge is often elicited. The clinical presentation of pancreatitis is variable and may be confused with other upper abdominal processes, such as peptic ulcer disease, acute biliary disease, or intestinal obstruction. Pain in the upper abdomen in the midline with radiation to the back associated with nausea and vomiting is typical of acute pancreatitis. Physical examination reveals tachycardia and mild hypotension secondary to fluid shifts. Tenderness is found in the epigastrium, often with evidence of peritoneal irritation. Leukocytosis, elevated serum amylase, and mild liver function test abnormalities are seen on laboratory evaluation. Ultrasound may reveal offending gallstones. CT scan of the retroperitoneum can evaluate the extent of pancreatic inflammation and exclude other etiologies for the abdominal pain. Treatment of uncomplicated pancreatitis is supportive, with volume expansion, analgesia, nasogastric decompression, and ventilatory support, if needed.

[edit] Small Intestine

[edit] Acute Mechanical Small Bowel Obstruction.

A relatively common cause of intestinal pain and a life-threatening process, small bowel obstruction has widely variable symptoms based on the site and underlying cause. Management requires prompt diagnosis and treatment to prevent intestinal strangulation and its associated high mortality. The most common causes are adhesions, hernia, and malignancy.

The patient with small bowel obstruction presents with often severe pain that is referred to the umbilical or epigastric areas. The pain is often spasmodic, which reflects bowel peristalsis attempting to alleviate the obstruction. Vomiting is almost always present; the frequency of emesis corresponds to the anatomic location of the obstruction. Patients with proximal obstruction have frequent, scant bilious vomiting, whereas those with distal obstruction tend to have infrequent, feculent emesis. The patient's initial vital signs are often normal. Tachycardia suggests dehydration and relative hypovolemia but also may reflect bowel ischemia. The temperature and blood pressure are usually normal. Physical examination shows evidence of dehydration with dry mucous membranes and wasted facies. Examination of the abdomen may reveal scars from previous abdominal surgery and varying degrees of abdominal distention. Distention is minimal or absent in patients with proximal obstruction and is often pronounced in those with distal obstruction. Bowel sounds may still be active in patients with early small bowel obstruction, intussusception, or ischemia. Mild abdominal tenderness is present. Evidence of localized peritonitis is an ominous finding and often reflects ischemic or strangulated bowel. All possible hernial orifices must be thoroughly examined. Laboratory data are often nondiagnostic. Elevated blood urea nitrogen and creatinine levels often reflect the degree of dehydration. Leukocytosis may indicate bowel ischemia in the patient with bowel obstruction. The diagnosis of obstruction is confirmed by supine and upright plain films of the abdomen, which reveal a ladderlike pattern of bowel loops with air-fluid levels (Fig. 107-3).

Figure 107-3 Upright (A) and supine (B) abdominal films reveal multiple loops of distended small bowel with air-fluid levels in patient with abdominal pain, nausea, and vomiting. Radiographic findings are diagnostic of small bowel obstruction.

The initial management of the patient with small bowel obstruction is nasogastric decompression and volume resuscitation. After correction of volume status, laparotomy is often required to alleviate the obstruction.

[edit] Meckel's Diverticulum.

The most common developmental abnormality of the small bowel is a Meckel's diverticulum, which is present in approximately 2% of the population. The omphalomesenteric duct fails to disappear completely, resulting in several possible anomalies, most often a diverticulum of the distal ileum. Patients may develop complications of ulceration, obstruction, bleeding, and acute inflammation. Symptoms may mimic appendicitis if acute inflammation is present, or the patient may present with obstructive symptoms. The diagnosis is often difficult to make preoperatively; however, a small bowel contrast study may demonstrate the offending diverticulum. Treatment is diverticulectomy when complications occur.

[edit] Colon

[edit] Acute Appendicitis.

Approximately 7% of individuals in Western countries develop appendicitis during their lifetime.^[2] Appendicitis should be included in the differential diagnosis of patients with abdominal pain because the physician rarely sees a patient with “classic” signs and symptoms of appendicitis. Prompt diagnosis is essential, since delay often will result in appendiceal rupture with increased morbidity and mortality. The peak age of acute appendicitis is approximately 20 years, although 10% of patients are younger than 10 or older than 50.^[2] These two populations are at highest risk of perforation because of atypical presenting symptoms and delay in diagnosis. Acute appendicitis must be included in the differential diagnosis of all patients presenting with acute abdominal pain.

The patient with appendicitis frequently has a history of “indigestion” and vague periumbilical discomfort. This is associated with vomiting and anorexia and alterations in bowel habit, with resulting diarrhea or increased flatulence. These early symptoms reflect the visceral response to the inflamed appendix. After these initial symptoms, the patient often describes movement of the pain from the periumbilical area to the right lower quadrant, with increased intensity. Vital signs may be within normal limits but usually reveal low-grade fever, typically 2° or 3° F above normal, and tachycardia. Abdominal examination shows tenderness in the right lower quadrant with evidence of local peritonitis. Tenderness at McBurney's point is not required for the diagnosis of appendicitis. Rectal examination reveals tenderness in the right hemipelvis, and at times an inflammatory mass can be palpated. Laboratory data may reveal a leukocytosis with a left shift, although the white blood cell count is normal in 20% of patients.^[3] In the female patient a pelvic ultrasound may be helpful to rule out a gynecologic process. Abdominal CT scan can be helpful when the diagnosis is unclear.

The history and physical examination are often sufficient to diagnose appendicitis. If the physician waits until diffuse peritonitis and abdominal rigidity are present, the diagnosis of appendicitis has been made too late and perforation has probably occurred. Treatment of appendicitis requires intravenous (IV) antibiotics and appendectomy.

[edit] Acute Diverticulitis.

Diverticulosis, the presence of multiple false diverticula of the colon, is a common disease in modernized countries and is found in approximately 50% of individuals over age 50 and almost 75% over 80.^[2] Diverticulosis remains asymptomatic in most patients, but about 20% develop the complications of bleeding or inflammation, leading to diverticulitis. Acute diverticulitis, which most often occurs in the sigmoid colon, is similar to appendicitis because both result from obstruction of a colonic diverticulum. The resulting increased intraluminal pressure subsequently causes the diverticulum to perforate. The paracolic tissues may locally contain this perforation, with a focal inflammatory process, or more extensive bacterial spillage may occur, with abscess formation or frank fecal peritonitis. Thus this disease process may have a varied clinical presentation.

An acute attack closely resembles the symptom complex of appendicitis except that the pain is in the left side of the abdomen. The pain often starts as vague discomfort in the midabdomen and then migrates to the left lower quadrant or suprapubic area. Anorexia, changes in bowel habit with either increased defecation or constipation, and dysuria secondary to bladder inflammation are also common symptoms. Physical findings include fever, left lower quadrant tenderness with evidence of local peritonitis, and abdominal distention; often a mass is palpated on abdominal examination and leukocytosis is found on laboratory evaluation. Rarely, there is free perforation of an inflamed diverticulum into the peritoneal cavity. The patient may present with systemic evidence of sepsis, including hemodynamic compromise and mental status deterioration. The abdomen is tender with evidence of diffuse tenderness.

Radiographic studies complement the clinical evaluation of diverticulitis. A plain film of the abdomen may reveal pneumoperitoneum if there is free perforation, or evidence of ileus may be seen. CT scan of the abdomen with oral and IV contrast shows effacement of the pericolic fat and may identify an abscess that could be drained under radiographic guidance. CT scan also helps identify other complications, such as fistulization.

Management of acute diverticulitis requires close observation; approximately 25% of hospitalized patients require surgical therapy. Initial treatment should include hospitalization for bowel rest, hydration, and appropriate IV antibiotics. Urgent surgery is required for patients with general or progressing peritonitis or evidence of systemic sepsis. Most patients improve in 2 to 3 days. If the patient has persistent pain, fever, leukocytosis, or peritonitis after 3 to 4 days of medical therapy, however, surgery is necessary. Diverticulitis recurs in approximately one third of medically treated patients, usually within the first 5 years. Indications for elective resection include recurrent diverticulitis, persistent symptoms, and the inability to rule out malignancy.

[edit] Inflammatory Bowel Disease.

See Chapter 108 .

[edit] Obstruction of the Large Intestine.

Unlike obstruction of the small bowel, colonic obstruction often presents with more subacute symptoms because of the large reservoir capacity of the colon and the slower peristaltic transit time. Colon cancer causes approximately 75% of colonic obstructions. Diverticular disease and acute volvulus are the other main causes.^[4]

The acute symptoms of colonic obstruction include colicky pain, increasing abdominal distention, and obstipation. Obstruction secondary to cancer or diverticular disease is precipitated by firm stool occluding a narrowed colonic lumen and occurs much more frequently in the left and sigmoid colon than the right colon. In contrast, a volvulus is caused by a twisting of the intestine on its mesentery, resulting in a closed-loop obstruction and subsequent vascular compromise of the gut; this usually occurs in the cecum or sigmoid colon. A thorough history often reveals previous symptoms, such as changes in stool caliber, episodes of hematochezia, and gradually increasing constipation that alternates with diarrhea. Vomiting is present if the ileocecal valve is incompetent. Physical examination is most remarkable for abdominal distention. Vital signs are usually within normal limits. A rectal examination may reveal an obstructing mass or demonstrate Hemoccult-positive stool. Laboratory data are usually unrevealing but may demonstrate iron deficiency anemia. An obstruction series shows a dilated colon with a lack of air in the rectum. If the ileocecal valve is incompetent, air is also seen in the small bowel, and this may resemble a partial small bowel obstruction. The plain radiograph of patients with volvulus reveals an extremely distended colonic coil with proximal dilated loops. If the diameter of the cecum is greater than 12 to 14 cm on radiographs, cecal ischemia and perforation are imminent. Barium enema may be helpful in diagnosing some obstructions and may be therapeutic in patients with sigmoid volvulus, but an enema should be reserved for select patients and only after discussion with a surgeon. Patients with suspected sigmoid volvulus may be treated with rigid sigmoidoscopy to untwist the loop of colon. Colonic obstruction requires urgent surgical intervention. Treatment includes IV hydration, appropriate preoperative antibiotics, gastric decompression, and urgent laparotomy.

[edit] Vascular Lesions

Aneurysmal disease of the abdominal aorta and intestinal ischemia can present as acute abdominal catastrophes.

[edit] Abdominal Aortic Aneurysm.

Abdominal pain associated with an aortic aneurysm is a symptom of present or impending rupture. The pain is throbbing in character and localizes to the back or loins. Cardiovascular collapse in the patient with a known aneurysm indicates rupture. Abdominal examination often reveals a pulsatile mass. The diagnosis of a leaking abdominal aortic aneurysm must be considered in the patient with acute abdominal and back pain. If the diagnosis is suspected, prompt surgical evaluation must be obtained before further workup. A history and physical examination consistent with a rupturing aneurysm are sufficient to implement surgical exploration.

[edit] Intestinal Ischemia.

Intestinal ischemia results in severe abdominal pain. Occlusive lesions secondary to mesenteric arterial thrombosis or embolism and low-flow states with resultant hypoperfusion of the gut can cause intestinal ischemia. The patient with occlusive vascular disease of the abdomen complains of cramping periumbilical pain and often has a history of postprandial abdominal angina or other clinical manifestations of atherosclerotic disease. A history of atrial dysrhythmias should increase suspicion of an embolic event. Nausea and diarrhea are often present. Abdominal examination may be unrevealing, but rectal examination is positive for gross or occult blood. Classically, pain out of proportion to physical findings is intestinal ischemia until proved otherwise. Radiographic evaluation may demonstrate ileus but is often nonspecific. The findings of fever, shock, and abdominal distention occur late in the disease process and often indicate a fatal outcome. Therefore close monitoring of all patients presenting with abdominal pain out of proportion to physical signs is essential. Premature discharge home may be followed by extensive bowel infarction.

Intestinal ischemia may involve the large or small bowel and can occur without any vascular occlusive lesion. Arteriography is indicated to evaluate the vascular anatomy and to rule out a correctable occlusive lesion. Treatment includes optimization of hemodynamic parameters with volume resuscitation and inotropic support as appropriate. Laparotomy with embolectomy or mesenteric revascularization is often required for definitive therapy. Bowel resection may be required if nonviable intestine is present. Surgery, however, is rarely beneficial. The prognosis for patients with nonocclusive ischemia is poor, with a mortality rate greater than 50%.

[edit] Urogenital Disease

Patients with processes involving the urinary or genital system may present with abdominal pain, although characteristically the pain is located in the groin or flank. Renal colic results from obstruction of a ureter secondary to a kidney stone, blood clot, or pus. The prominent symptom is sudden severe pain in the flank, often radiating to the groin, and is associated with emesis and dysuria. Abdominal examination demonstrates no tenderness. A urinalysis may reveal hematuria and pyuria. A plain film may demonstrate the offending calculus, but an IV pyelogram may be necessary to provide a definitive diagnosis.

Acute infection of the kidney may also present with abdominal pain, but pain is typically described in the flank. High fever (greater than 103° F [39.4° C]) and shaking chills with dysuria are typical symptoms. Examination may reveal abdominal tenderness, although costovertebral angle tenderness is more common. Laboratory evaluation reveals leukocytosis and pyuria. Treatment is with hydration and IV antibiotics.

In the female patient, gynecologic causes for acute abdominal pain must also be included in the differential diagnosis. Ectopic pregnancy, pelvic inflammatory disease, ovarian torsion, and ovarian cystic disease can mimic gastrointestinal disease. A thorough history, physical examination, and appropriate laboratory evaluation, including a pregnancy test, are required for accurate diagnosis. A transvaginal ultrasound of the pelvic organs supplements the history and examination. These gynecologic disease processes are discussed under Women's Health (see especially Chapters 44 and 46 ).

[edit] MEDICAL DIAGNOSES THAT SIMULATE ACUTE SURGICAL PROCESS

Several medical causes of the acute abdomen should be included in the differential diagnosis of the patient with acute abdominal pain. A thorough history, with attention to past medical problems, and physical examination can usually identify these conditions. Abdominal pain must not be attributed to a medical etiology, however, until acute surgical disease processes are ruled out conclusively, which may require laparotomy (Box 107-2).

[edit] REFERENCES