Abdominal Pain

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Chapter 27

Abdominal Pain

Perspective

Abdominal pain is a common emergency department (ED) complaint but for many reasons is often diagnostically challenging. The nature and quality of abdominal pain may be difficult for the patient to convey. Physical examination findings are variable and can be misleading. The location and severity of the pain may change over time. Initially benign symptoms and presentations may evolve into life-threatening conditions. Conversely, patients with severe symptoms may carry a relatively benign diagnosis. All of these factors make evaluation of patients with acute abdominal pain challenging in the ED setting.

Epidemiology

Abdominal pain accounts for up to 10% of all ED visits. Some of the most common causes of acute abdominal pain are listed in Table 27-1. Many patients have pain and other symptoms that are not typical of any specific disease process. Even after ED workup, a diagnosis may not be found in some patients. In addition, several adult groups deserve special consideration: elders (those older than 65 years of age), the immunocompromised, and women of reproductive age.

Elders with acute abdominal pain are more likely to have a life-threatening process as the cause of their pain. Conditions such as diverticulitis, ruptured abdominal aneurysm, or mesenteric ischemia may manifest atypically and be rapidly progressive. Decreased diagnostic accuracy, coupled with increased probability of severe disease, results in increased mortality in elderly patients with abdominal pain.

Increasingly, emergency physicians are seeing patients in immunocompromised states secondary to human immunodeficiency virus and acquired immunodeficiency syndrome (HIV/AIDS), uncontrolled diabetes, chronic liver disease, chemotherapy, and immunosuppressive drugs. For many reasons, these patients also prove challenging. Their clinical presentation can be misleading owing to atypical physical and laboratory findings, such as lack of fever. The white blood cell (WBC) count, which is unreliable in all cases of abdominal pain, may be frankly misleading in such patients, such as in those with persistent elevations. With regard to infection, the scope of the differential diagnosis also should be broader than usual.1,2 Presentations in the immunocompromised patient may be highly variable and subtle and are discussed in Chapter 183.

The evaluation of abdominal pain in women involves a differential diagnosis of considerable extent and often requires a more in-depth physical examination and further diagnostic testing. Pelvic organs may be the source of significant pathology in both the pregnant and the nonpregnant patient. The possibility of ectopic pregnancy in women of reproductive age greatly increases the risk of serious disease with a high potential for misdiagnosis. During pregnancy the uterus becomes an abdominal rather than a pelvic organ and may displace the normal intraperitoneal contents, adding complexity to the evaluation of these patients. Nonpregnant patients require evaluation for various ovarian and uterine pathologic states.

Pathophysiology

Pathology in the gastrointestinal and genitourinary tracts remains the most common source of pain perceived in the abdomen. Also, pain can arise from a multitude of other intra-abdominal and extra-abdominal locations (Box 27-1). Abdominal pain is derived from one or more of three distinct pain pathways: visceral, somatic, and referred.

BOX 27-1

Important Extra-abdominopelvic Causes of Abdominal Pain

Adapted from Purcell TB: Nonsurgical and extraperitoneal causes of abdominal pain. Emerg Med Clin North Am 7:721, 1989.

Visceral pain results from stimulation of autonomic nerves invested in the visceral peritoneum surrounding internal organs. It is often the earliest manifestation of a particular disease process. Distention of hollow organs by fluid or gas and capsular stretching of solid organs from edema, blood, cysts, or abscesses are the most common stimuli. This discomfort is poorly characterized and difficult to localize. If the involved organ is affected by peristalsis, the pain often is described as intermittent, crampy, or colicky. In general, visceral pain is perceived from the abdominal region that correlates with the embryonic somatic segment, as follows:

Visceral pain can be perceived in a location remote from the actual disease process. Localization occurs with the extension of the disease process beyond the viscera. A classic example is that of the early periumbilical pain of appendicitis (midgut). When the parietal peritoneum becomes involved, the pain localizes to the right lower quadrant of the abdomen, the usual location of the appendix.

Somatic pain occurs with irritation of the parietal peritoneum. This is usually caused by infection, chemical irritation, or another inflammatory process. Sensations are conducted by the peripheral nerves and are better localized than the visceral pain component. Figure 27-1 illustrates some more typical pain locations corresponding to specific disease entities. Somatic pain is often described as intense and constant. As disease processes evolve to peritoneal irritation with inflammation, better localization of the pain to the area of pathology generally occurs.

Referred pain is defined as pain felt at a distance from its source because peripheral afferent nerve fibers from many internal organs enter the spinal cord through nerve roots that also carry nociceptive fibers from other locations, as illustrated in Figure 27-2. This makes interpretation of the location of noxious stimuli difficult for the brain. Both visceral pain and somatic pain can manifest as referred pain. Two examples of referred pain are the epigastric pain associated with an inferior myocardial infarction and the shoulder pain associated with blood in the peritoneal cavity irritating the diaphragm. It is common for a patient to interpret pain originating from the hips as pelvic pain, especially in the very young or elderly. Lower lobe pneumonias can cause referred abdominal pain secondary to diaphragmatic irritation. Finally, some metabolic disorders and toxidromes may manifest with abdominal pain.

Gynecologic and obstetric presentations are discussed in other chapters. Notably, abdominal pain in a female may represent referred pain from pelvic structures or an extension of a pelvic process, as in the case of perihepatic inflammation with pelvic inflammatory disease.

Diagnostic Approach

The clinical approach should focus on early stabilization, history, physical examination, and any ancillary tests collectively facilitating appropriate management and disposition plans.

Differential Considerations

Classically, potential diagnoses are divided into intra-abdominopelvic (intraperitoneal, retroperitoneal, and pelvic) causes (e.g., appendicitis, cholecystitis, pancreatitis) and extra-abdominopelvic processes (e.g., pneumonia, myocardial infarction, ketoacidosis, toxicologic).

Although significant morbidity and mortality can result from many disorders causing abdominal pain, a few processes warrant careful consideration in the ED. Table 27-2 lists important potentially life-threatening nontraumatic causes of abdominal pain. This group represents the major causative disorders likely to be associated with hemodynamic compromise and for which early therapeutic intervention is critical.

Rapid Assessment and Stabilization

As with any complaint, triage is the first critical step in management. Most patients with abdominal pain do not have hemodynamic instability, although a small proportion of these stable-appearing patients may have a life-threatening process. This percentage is higher in elders and immunocompromised patients.

Physiologically compromised patients should be brought to a treatment area immediately, and resuscitation initiated. Sepsis or protracted severe volume loss (emesis, diarrhea) can lead to shock; prompt resuscitation is required.

Extreme conditions, such as ruptured abdominal aortic aneurysm, massive gastrointestinal hemorrhage, ruptured ectopic pregnancy, ruptured spleen, and hemorrhagic pancreatitis, may necessitate blood or blood product replacement. Bedside ultrasonography can be used to quickly evaluate patients for free intraperitoneal fluid, volume status, and presence of aortic pathology. Ultrasound assessment should be part of the initial physical examination and can be invaluable in guiding treatment and disposition. Because any of the immediately life-threatening entities may necessitate surgical intervention or management, early surgical consultation is indicated.

Pivotal Findings

Symptoms

A careful and focused history is central to unlocking the puzzle of abdominal pain. Box 27-2 lists some historical questions with high yields for serious pathology. Language and cultural differences may influence accurate communication and mutual understanding; therefore use of an accurate interpreter can be invaluable.

BOX 27-2

High-Yield Historical Questions

1. How old are you? Advanced age means increased risk.

2. Which came first—pain or vomiting? Pain first is worse (i.e., more likely to be caused by surgical disease).

3. How long have you had the pain? Pain for less than 48 hours is worse.

4. Have you ever had abdominal surgery? Consider obstruction in patients who report previous abdominal surgery.

5. Is the pain constant or intermittent? Constant pain is worse.

6. Have you ever had this before? A report of no prior episodes is worse.

7. Do you have a history of cancer, diverticulosis, pancreatitis, kidney failure, gallstones, or inflammatory bowel disease? All are suggestive of more serious disease.

8. Do you have human immunodeficiency virus (HIV)? Consider occult infection or drug-related pancreatitis.

9. How much alcohol do you drink per day? Consider pancreatitis, hepatitis, or cirrhosis in patients with history or signs of significant intake.

10. Are you pregnant? Test for pregnancy—consider ectopic pregnancy.

11. Are you taking antibiotics or steroids? Effects of these drugs may mask infection.

12. Did the pain start centrally and migrate to the right lower quadrant? High specificity for appendicitis.

13. Do you have a history of vascular or heart disease, hypertension, or atrial fibrillation? Consider mesenteric ischemia and abdominal aneurysm.

From Colucciello SA, Lukens TW, Morgan DL: Abdominal pain: An evidence-based approach. Emerg Med Pract 1:2, 1999.

Abrupt onset often is indicative of a more serious cause; however, delayed presentations also may represent a surgical condition. Surgical causes of abdominal pain are more likely to manifest with pain first, followed by nausea and vomiting, rather than with nausea and vomiting followed by pain, although in elder patients the progression may be reversed or pain may be absent entirely. Localization and pain migration also are helpful components of the pain history. Diffuse pain generally is nonsurgical, but it may represent the early visceral component of a surgical process. Colicky pain is indicative of hollow viscus distention, and duration and time of colic may give clues to the identity of the culprit organ, as displayed in Figure 27-3.

The severity and descriptive nature of the pain are the most subjective aspects of the pain history, but a few classic descriptions are recognized, such as the following:

A thorough review of the patient’s past medical history and medications is also mandatory, as this frequently provides key information about the current presentation. A history of immunocompromised state or immunosuppressive medications may point to infection. A patient undergoing anticoagulation therapy or taking nonsteroidal anti-inflammatory medications may have gastrointestinal bleeding. Diabetics may be experiencing abdominal pain as a feature of ketoacidosis. A patient undergoing chronic narcotic therapy may have constipation or even a bowel obstruction.

Signs

The objective evaluation begins with measurement of the vital signs. Significant tachycardia and hypotension are indicators that hypovolemia or sepsis may be present. Tachypnea may be an indication of metabolic acidosis from gangrenous viscera or sepsis, hypoxemia from pneumonia, or simply a catecholamine-induced reaction to pain. Elevated temperature often is associated with intra-abdominal infections. Although important, vital signs may be misleading and should be interpreted in the context of the entire presentation. Tachycardia may develop late for various reasons in hypovolemia. Temperature often is normal in elderly patients with laparotomy-proven intraperitoneal infections. Elders with sepsis also may demonstrate hypothermia.

A thorough abdominal examination is an essential part of evaluation of the patient with abdominal pain. This requires properly positioning the patient supine and exposing the abdomen. The examination should begin with inspection for any signs of trauma, bruising, or skin lesions. The patient should be asked to localize the area of maximal tenderness by pointing with one finger. The abdomen can be divided into four quadrants: right upper, right lower, left upper, and left lower; each area is then examined individually. Tenderness in one quadrant often corresponds with the location of the diseased organ, which will direct the workup (see Fig. 27-1). Some disease processes may manifest with pain that is not exclusively within one specific quadrant, such as the suprapubic pain of a urinary tract infection or the midepigastic pain of a gastric ulcer. Although most patients with suspected appendicitis have right lower quadrant abdominal tenderness, a small percentage of patients with proven appendicitis do not.

Rectal examination may have limited use in the evaluation of abdominal pain, except that associated with intraluminal gastrointestinal hemorrhage, prostatitis, or perirectal disease. The main utility of the rectal examination is in the detection of heme-positive stool, anal fissures or fistulae, or stool impaction. Rectal examination has not been shown to increase diagnostic accuracy for appendicitis when added to external physical examination of the abdomen.

The abdominal evaluation should include a pelvic examination in female patients with lower abdominal pain and genital examination in male patients. The pelvic examination should be done early in the evaluation of the female patient with abdominal pain to help differentiate an abdominal from a pelvic source. This information is helpful in choosing an imaging modality. Pelvic ultrasound examination is helpful in evaluating uterine and ovarian pathology, whereas computed tomography (CT) is more beneficial in evaluation of suspected intra-abdominal pathology. Although the pelvic examination may guide the initial choice of imaging modality, overlap in examination findings is common. For example, a patient with right lower quadrant tenderness may have both right adnexal tenderness and tenderness over McBurney’s point, necessitating exclusion of both appendicitis and ovarian torsion. The diagnosis highest on the differential list should be ruled out first through use of the corresponding imaging modality.

In the male patient with abdominal pain, the urogenital examination is a routine and required part of the evaluation. Diseases such as prostatitis, orchitis, and epididymitis commonly cause abdominal pain in males. Furthermore, inguinal hernias are more common in males, with the possibility of strangulation or incarceration in the inguinal canal, necessitating a thorough genitourinary examination.

In view of the evolving nature of abdominal pain, repetitive examinations may be useful. This is common practice with respect to suspected appendicitis and has improved the diagnostic accuracy in patients whose presentations were atypical.

Ancillary Testing

Urinalysis and testing for pregnancy are perhaps the most time- and cost-effective adjunctive laboratory tests available. Results often can be obtained quickly, so the former can lead to an early diagnosis and the latter may significantly affect further evaluation and management approaches. It is necessary to interpret urinalysis results within the context of the patient’s clinical picture. Pyuria, with or without bacteriuria, often is present in a variety of conditions besides a simple urinary tract infection. For example, appendicitis may feature sterile pyuria. Similarly, hematuria usually is present with the relatively benign condition of nephrolithiasis but also may indicate a more severe pathology.

Complete blood counts frequently are ordered for patients with abdominal pain, but findings seldom are contributory to a diagnosis. Despite the association of elevated WBC counts with many infectious and inflammatory processes, the WBC count is neither sufficiently sensitive nor sufficiently specific to be considered a discriminatory test to help establish or rule out a serious cause for the pain. Even serial WBC counts have failed to differentiate surgical from nonsurgical conditions. The WBC count is therefore not helpful for diagnosis, except when a low WBC indicates immunosuppression. Serum electrolytes, even in the presence of protracted emesis or diarrhea, are abnormal in less than 1% of patients. Blood urea nitrogen concentrations can be elevated in gastrointestinal hemorrhage and dehydration, but such conditions are better detected and quantified by history and physical examination. Increased serum creatinine usually is indicative of renal dysfunction. Blood glucose, anion gap, and serum ketone determinations are useful in diabetic ketoacidosis, one cause of acute abdominal pain and tachypnea.

Liver enzymes and coagulation studies are helpful only in a small subset of patients with suspected liver disease. If pancreatitis is suspected, the most useful diagnostic result is serum lipase elevated to at least double the normal value, because it is more specific and more sensitive than serum amylase for this process. Measurement of serum amylase is of no value if a serum lipase level is available.3 Serum lactate levels are elevated late in bowel ischemia, and such determination may be useful if this entity is suspected, but serum lactate levels cannot be considered either sufficiently sensitive or specific enough to establish or exclude the diagnosis on their own.

Plain radiography of the abdomen has limited usefulness in the evaluation of acute abdominal pain and should be performed only when bowel obstruction or radiopaque foreign body is suspected and there is no intent to obtain a CT scan. For suspected perforated hollow viscus, an upright chest radiograph is a better study than an abdominal film but is not indicated if the plan is to proceed to CT scan regardless of the findings on the plain film. CT of the abdomen has become the imaging modality of choice with nonobstetric, nonbiliary abdominal pain. It allows visualization of both intraperitoneal and extraperitoneal structures and has a high degree of accuracy. Incidental findings are common on CT scans and may lead to a diagnosis. CT scan results often lead to a change in diagnosis.4 The proper execution and interpretation of CT studies will reduce morbidity, mortality, and medical expenses.5,6 CT is not indicated for biliary disease, however, for which ultrasound is a much better modality.

CT has increased diagnostic utility in elderly patients for several reasons. Older people with abdominal pain are significantly more likely to require surgery and have a greatly increased mortality compared with younger adults. Furthermore, evaluation of abdominal pain in elders often is more challenging owing to unreliable findings on physical examination, including vital signs, difficulties in history taking, physiologic age-related changes, and comorbid conditions. In the elderly population, CT results change management or disposition decisions in a significant proportion of patients.7 Table 27-3 lists the most common findings on CT scans in elders with abdominal pain.

Table 27-3

Most Common Diagnostic Computed Tomography (CT) Findings in Older Patients in the Emergency Department with Acute Abdominal Pain

image

From Hustey FM, et al: The use of abdominal computed tomography in older ED patients with acute abdominal pain. Am J Emerg Med 23:259-265, 2005.

Some controversy surrounds the use of oral contrast in abdominal CT in the critically ill ED patient. Technologic advances have improved image acquisition and resolution, and several studies have shown that intravenous contrast alone may now be adequate in the evaluation of certain suspected pathologic processes, such as solid organ or bowel wall disease.8 CT with intravenous contrast alone also has been shown to be sensitive and specific for the confirmation or exclusion of acute appendicitis.9 The exclusion of oral contrast in these patients significantly decreases ED time to disposition and improves patient satisfaction.

Controversy also surrounds the use of CT with regard to radiation exposure that patients receive. Several studies have attempted to quantify the radiation exposure associated with CT, but in reality there is a wide variation in dosage among different types of CT studies. One study estimated an abdominal CT with intravenous contrast to produce a dose of 10 to 50 millisieverts (mSv), enough to increase the lifetime risk of cancer to 1 in 470 in a 20-year-old woman.10 Another study demonstrated that although patients were more confident when CT imaging was part of their ED workup, they had a very poor understanding of the radiation dose involved.11 CT is an important adjunct in ED care, but the decision to scan is carefully weighed against the patient’s history, physical examination findings, age, and gender. In particular, a patient with a history of chronic undifferentiated abdominal pain, multiple previous CT scans, and alternative diagnoses may benefit from observation as opposed to another CT scan.

Bedside transabdominal and transvaginal ultrasonography have emerged as extremely useful adjuncts, decreasing time to diagnosis of life-threatening abdominopelvic conditions. Useful indications include the following:

The results of sonographic examinations are operator dependent, and misdiagnosis can occur because of failure to detect or identify pathology, incorrect identification of normal anatomy as pathologic, or overinterpretation of correctly identified findings (e.g., the mere presence of gallstones does not indicate that cholelithiasis is the cause of the pain). Emergency physicians should receive proper training in image acquisition and interpretation, and ultrasound evaluation in the radiology department or other confirmatory imaging such as CT should be sought if there is ambiguity or uncertainty in findings.

Differential Diagnosis

The differential considerations with abdominal pain include a significant number of potentially life- or organ-threatening entities, particularly in the setting of a hemodynamically unstable or toxic-appearing patient. Severely ill patients require timely resuscitation and expeditious evaluation for potentially life-threatening conditions. A focused history and examination should be conducted, and the patient should be placed in a monitored acute care area well equipped for airway control, quick intravenous access, and fluid administration. Only then should appropriate diagnostics be initiated (bedside focused assessment with sonography in trauma [FAST], aorta ultrasound assessment, and radiographic, electrocardiographic, and laboratory studies). This approach is particularly important in dealing with elder or potentially pregnant patients (see Tables 27-1 and 27-2).

Women of reproductive age with abdominal pain should undergo pregnancy testing early, and a known pregnancy or a positive result on urine or serum pregnancy testing associated with abdominal pain in the ED should be considered to represent an ectopic pregnancy until proved otherwise. If evidence of blood loss is present, early obstetric consultation and diagnostic ultrasonography should be promptly sought. Bedside transabdominal sonography may identify free intraperitoneal fluid during the evaluation of shock, which may be sufficient evidence to justify operative intervention in the context of a positive pregnancy test and appropriate history and physical examination findings.

Despite the limitations already described, the approach to the differential diagnosis of abdominal pain generally is based on the location of maximum tenderness. Figure 27-1 shows locations of subjective pain and maximal tenderness on palpation related to various underlying causes. In women of childbearing age, a positive result on pregnancy testing may indicate ectopic pregnancy, but the entire spectrum of intra-abdominal conditions remains in the differential diagnosis, as for the nonpregnant patient. When the very broad differential list is compartmentalized by both history and physical examination, ancillary testing should proceed to either confirm or support the clinical suspicion.

Despite the significant variety of tests available, close to one half of the patients in the ED with acute abdominal pain will have no conclusive diagnosis. It is incumbent on the clinician to reconsider the extra-abdominal causes of abdominal pain (see Box 27-1), with special consideration in elders and immunocompromised patients, before arriving at the diagnosis of “nonspecific abdominal pain.”

Empirical Management

The main therapeutic goals in managing acute abdominal pain are physiologic stabilization, mitigation of symptoms (e.g., emesis control, pain relief), and expeditious diagnosis, with consultation if required.

There is no evidence to support withholding analgesics from patients with acute abdominal pain to preserve the accuracy of subsequent abdominal examinations; in fact, the preponderance of evidence supports the opposite. Pain relief may facilitate the diagnosis in patients ultimately requiring surgery.12 In the acute setting, analgesia usually is accomplished with intravenously titrated opioids. Meperidine (Demerol) has an unfavorable side effect profile and should be avoided. Intravenous ketorolac, the only parenteral nonsteroidal anti-inflammatory drug available in North America, is useful for both ureteral and biliary colic,13 as well as some gynecologic conditions, but is not indicated for general treatment of undifferentiated abdominal pain. Ketorolac has been shown to cause increased bleeding times in healthy volunteers; it should be avoided in patients with gastrointestinal bleeding and potential surgical candidates.14

Aside from analgesics, a variety of other medications may be helpful to patients with abdominal pain. The burning pain caused by gastric acid may be relieved by antacids.15 Intestinal cramping may be diminished with oral anticholinergics, such as the combination agent atropine-scopolamine-hyoscyamine-phenobarbital (Donnatal), although evidence for this is scant and highly variable.

Antiemetics such as promethazine, prochlorperazine, ondansetron, or droperidol can be useful for nausea and vomiting. Gastric emptying by nasogastric tube with suction is appropriate for suspected small bowel obstruction with intractable pain and vomiting.

If intra-abdominal infection is suspected, broad-spectrum antibiotic therapy should be initiated promptly. Abdominal infections are often polymicrobial, and coverage for enteric gram-negative, gram-positive, and anaerobic bacteria is included. In the choice of antibiotic or combination, the following should be considered:

Whether to provide coverage for Enterococcus species is still a subject of debate, and the decision to treat for these bacteria specifically can be made after consultation. Immunocompromised patients may require antifungal agents.

Disposition

Because up to 40% of patients with acute abdominal pain receive the diagnosis of nonspecific abdominal pain, decisions regarding disposition can be as difficult as the diagnosis in these patients. Categories for disposition may include surgical versus nonsurgical consultation and management, admission for observation, and discharge to home with follow-up evaluation. The decision to admit a patient to an observation unit or a hospital bed factors in the following:

Clinically stable patients may be discharged from the ED with appropriate follow-up care, possibly to include repeated physical examination or additional diagnostic imaging if indicated.

In the case of nonspecific abdominal pain that is considered potentially worrisome, CT scan, observation (i.e., in the ED observation unit), or follow-up reevaluation after 8 to 12 hours all are valid options. Follow-up evaluation can be done through a return visit to the ED, via an appointment with a primary care physician, or as part of an observation unit protocol.

Before discharge of a patient with an undiagnosed cause of nonspecific abdominal pain, several conditions should be met. The abdominal examination findings should not indicate serious organ pathology or peritoneal irritation, and the patient should have normal or near-normal vital signs. Pain and nausea should be controlled, and the patient should be able to take fluids by mouth. If a patient is to be discharged home without a specific diagnosis, clear instructions are given and include the following information:

References

1. Mönkemüller, KE, Lazenby, AJ, Lee, DH, Loudon, R, Wilcox, CM. Occurrence of gastrointestinal opportunistic disorders in AIDS despite the use of highly active antiretroviral therapy. Dig Dis Sci. 2005;50:230.

2. Wernck-Silva, AL, Prado, IB. Dyspepsia in HIV-infected patients under highly active antiretroviral therapy. J Gastroenterol Hepatol. 2007;22:1712.

3. Pratt, DS, Kaplan, MM. Evaluation of abnormal liver-enzyme results in asymptomatic patients. N Engl J Med. 2000;342:1266.

4. Lewis, LM, et al. Quantifying the usefulness of CT in evaluating seniors with abdominal pain. Eur J Radiol. 2007;61:290.

5. Federle, MP. CT of the acute (emergency) abdomen. Eur Radiol. 2005;15(Suppl 4):D100.

6. Stromberg, C, Johansson, G, Adolfson, A. Acute abdominal pain: Diagnostic impact of immediate CT scanning. World J Surg. 2007;31:2347.

7. Esses, D, et al. Ability of CT to alter decision making in elderly patients with acute abdominal pain. Am J Emerg Med. 2004;22:270.

8. Lee, SY, et al. Prospective comparison of helical CT of the abdomen and pelvis without and with oral contrast in assessing acute abdominal pain in adult emergency department patients. Emerg Radiol. 2006;12:150.

9. Mun, S, et al. Rapid diagnosis of acute appendicitis with IV contrast material. Emerg Radiol. 2006;12:99.

10. Smith-Bindman, R, et al. Radiation dose associated with common computed tomography examinations and the associated lifetime attributable risk of cancer. Radiology. 2009;169:2078.

11. Baumann, BM, et al. Patient perceptions of computed tomographic imaging and their understanding of radiation risk and exposure. Ann Emerg Med. 2011;58:1–7.

12. Thomas, SH, et al. Effects of morphine analgesia on diagnostic accuracy in emergency department patients with abdominal pain: A prospective, randomized trial. J Am Coll Surg. 2003;196:18.

13. Henderson, SO, Swadron, S, Newton, E. Comparison of intravenous ketorolac and meperidine in the treatment of biliary colic. J Emerg Med. 2002;23:237.

14. Singer, AJ, Mynster, CJ, McMahon, BJ. The effect of IM ketorolac tromethamine on bleeding time: A prospective, interventional, controlled study. Am J Emerg Med. 2003;21:441.

15. Berman, DA, Porter, RS, Graber, M. The GI cocktail is no more effective than plain liquid antacid: A randomized, double blind clinical trial. J Emerg Med. 2003;25:239.

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