The following cases and commentary, which address diagnosing and managing pain, are excerpted from ACP's Medical Knowledge Self-Assessment Program (MKSAP14).
Case 1: Mid-abdominal pain
A 45-year-old man is evaluated for a six-month history of midabdominal pain, fatigue and a 2.26-kg (5-lb) weight loss. He has a longstanding history of constipation-predominant irritable bowel syndrome (IBS) but reports the current abdominal pain is different from that associated with his previous IBS symptoms. He has no diarrhea, hematochezia, melena or genitourinary complaints. He reports no alcohol or drug use and has undergone no previous surgical procedures.
Physical examination is normal except for moderate obesity (weight of 118 kg [260 lb]) and some mild, midabdominal tenderness but no hepatosplenomegaly, masses, guarding or rebound tenderness. Laboratory studies, including hemoglobin, serum creatinine level, liver chemistry tests, serum lipase level and urinalysis, are normal. Results of colonoscopy are also normal.
Which of the following is the most appropriate next radiological imaging test in this patient?
A. MRI of the abdomen
B. Magnetic resonance cholangiopancreatography
C. CT of the abdomen
D. CT colonography
E. Abdominal ultrasound
Case 2: End-stage metastatic prostate cancer
A 64-year-old man with end-stage metastatic prostate cancer is experiencing worsening skeletal pain throughout his back and bilateral lower extremities. He has already experienced disease progression with anti-hormonal therapy, has refused further chemotherapy and has received the maximal dose of radiation to the spine and metastatic lesions. He had been controlling his pain with regular use of nonsteroidal anti-inflammatory drugs but now requires short-acting narcotics almost every four to six hours. He is requesting a long-acting medication for his pain control, and his current health insurance does not include a pharmacy benefit.
The remainder of the medical history is noncontributory. On physical examination, no focal neurologic findings are noted. Results of renal function and liver chemistry tests are normal.
Which of the following is the most cost-effective choice for long-acting analgesia medication in this patient?
A. Long-acting morphine
B. Long-acting oxycodone
C. Transdermal fentanyl
Case 3: Anterior chest pain of sudden onset
A 72-year-old man is evaluated in the emergency department for the sudden onset of severe sharp anterior chest pain radiating into the back. He is a former smoker with a long history of type 2 diabetes mellitus, chronic renal insufficiency (creatinine 2.0 mg/dL [176.84 µmol/L]), sick sinus syndrome with a DDD pacemaker implanted in 1995 and hypertension. His medications include insulin, furosemide, ramipril and aspirin.
On examination, the blood pressure is 185/85 mm Hg bilaterally, and the pulse rate is 90 beats per minute and regular. A 2/6 systolic murmur and soft decrescendo diastolic murmur are heard at the second right intercostal space. There are abdominal and bilateral femoral bruits, with absent distal pulses.
Which of the following is the most appropriate initial imaging study?
A. Non-contrast chest CT
B. Chest MRI
C. Transesophageal echocardiography
D. Transthoracic echocardiography
Case 4: Nonradiating mid-scapular pain
A 32-year-old man is evaluated in the emergency department for a one-week history of sharp, nonradiating mid-scapular pain that has become increasingly severe over the last two hours. The patient has been previously healthy and does not smoke. His medical history is significant only for an automobile accident four years ago, when he hit a tree, resulting in a ruptured spleen. He takes no medications.
On physical examination, the blood pressure is 134/86 mm Hg bilaterally, and heart rate is 56 beats per minute and regular. The lungs are clear, and cardiac and abdominal examinations are normal. Electrocardiogram shows sinus bradycardia. Chest radiograph shows a normal cardiac silhouette and normal mediastinum.
What is the most likely cause of his symptoms?
A. Ascending aortic dissection
B. Aortic coarctation
C. Aortic transection
D. Takayasu's arteritis
E. Penetrating aortic ulcer
Case 5: Chest pain in pregnancy
A 22-year-old woman who is 16 weeks pregnant is evaluated for a two-hour history of severe anterior chest pain radiating to her mid-back. She is a tall, thin woman with a pectus abnormality of her chest and long, thin fingers. Her blood pressure is 140/80 mm Hg, her pulse is 94 beats per minute and regular and her respiratory rate is 24 breaths per minute. Her chest wall is diffusely mildly tender to palpation. Her lungs are clear to auscultation. Cardiac auscultation shows a normal S1, a physiologically split S2 and a grade 2/6 diastolic decrescendo murmur at the left sternal border. There is no peripheral edema. Her electrocardiogram shows only nonspecific ST-T changes. Oxygen saturation by pulse oximetry on room air is 99%. Her D-dimer level is mildly elevated.
Which is the most likely cause of her chest pain?
A. Pulmonary embolus
B. Acute myocardial infarction
C. Aortic dissection
Case 6: Sharp substernal chest pain
A 49-year-old man with severe chest pain is seen urgently in the emergency department. The chest pain, which began abruptly three hours ago, is substernal, sharp in quality, and has been very intense from its onset. He reports no prior fever, cough, dyspnea, or hemoptysis. He has a longstanding history of hypertension and chronic obstructive pulmonary disease. His medications include lisinopril, 20 mg daily, and ipratropium inhaler.
On physical examination, the patient is diaphoretic and listless but answers questions appropriately. He complains of chest pain. His temperature is 37.2 °C (99.0 °F). His pulse rate is 126 beats per minute and his respiratory rate is 26 breaths per minute. Systolic blood pressure is 88 mm Hg in the right arm and 58 mm Hg in the left arm. Pulsus paradoxus is 16 mm Hg. Central cyanosis is present. Jugular veins are distended with an approximated pressure of 12 cm H2O. Lungs are clear except for faint end-expiratory wheezes. On cardiac examination, the point of maximal impulse is nonpalpable. Heart sounds are normal in intensity. No murmur or gallops are auscultated. The lower extremities show no edema.
Laboratory results include a hemoglobin of 11 mg/dL (110 g/L), urea nitrogen of 18 mg/dL (6.43 mmol/L), and creatinine of 1.1 mg/dL (97.26 µmol/L). Chest radiograph shows a widened mediastinum and clear lung fields.
Rapid infusion of 2 liters of normal saline and dopamine, 20 µg/kg per minute, fails to raise blood pressure. Two-dimensional echocardiography demonstrates a small to moderate-sized circumferential pericardial effusion. Electrocardiography shows sinus tachycardia and no acute changes.
What is the most likely diagnosis in this patient?
B. Bacterial pericarditis
C. Aortic dissection
D. Acute myocardial infarction
E. Pulmonary embolus
Answers and commentary
Correct answer: C. CT of the abdomen.
Abdominal CT is superior to MRI or ultrasonography for imaging most conditions involving the bowel. It is also better than MRI for evaluating urolithiasis, although the latter is an unlikely diagnosis in this patient. CT is less costly than MRI and requires less patient cooperation. It has some limitations in visualizing common bile duct stones and the female pelvic organs, but this patient is a male, and biliary obstruction is not suspected based on his clinical presentation.
MRI of the abdomen is effective in viewing parenchymal lesions, especially in the liver. However, there is nothing in this patient's history or physical examination findings suggestive of hepatobiliary disease, and MRI is more costly than CT. Magnetic resonance cholangiopancreatography is a noninvasive option to endoscopic retrograde resonance cholangiopancreatography for evaluating biliary or pancreatic abnormalities and would typically be reserved for patients in whom clinical evaluation, laboratory tests or initial imaging studies suggested a biliary or pancreatic lesion. CT colonography has principally been studied as an alternative to colonoscopy for colorectal cancer screening rather than for the diagnostic evaluation of chronic abdominal pain. Its sensitivity and specificity are slightly inferior to those of colonoscopy and would not be warranted in this patient, whose colonoscopy results were normal. Ultrasonography is a rapid, inexpensive option, particularly useful in establishing a diagnosis of gallbladder disease, including common bile duct stones, but the presence of gallbladder disease is unlikely in this patient based on his clinical scenario. Ultrasonography is also more operator-dependent than other imaging techniques and may have poor resolution in the setting of obesity.
- Abdominal CT is superior to MRI or ultrasonography for imaging most conditions involving the bowel, is less costly than MRI, and requires less patient cooperation.
- CT has limitations in evaluating the female pelvic organs or visualizing common bile duct stones.
Correct answer: A. Long-acting morphine.
This patient has chronic, progressive metastatic cancer-induced pain that is not alleviated by standard short-term pain management. He requires high-dose, escalating, long-acting narcotic analgesia, and in this setting, morphine would be appropriate.
There is no evidence that any long-acting narcotic is better than another such agent. In particular, oxycodone has similar efficacy to morphine and is appropriate for use in patients with cancer-related pain. However, oxycodone is considerably more expensive than morphine, and because there is no evidence of its improved efficacy or a better side effect profile compared with morphine, it would be appropriate to first use the lowest-cost alternative of agents with comparable efficacy.
Transdermal fentanyl is also a useful long-acting narcotic but is considerably more expensive than long-acting morphine and is often used in patients who have limitations on oral intake or intolerance to other long-acting narcotics.
Duloxetine is a new antidepressant drug with an approved indication for some chronic pain syndromes but would not be an appropriate alternative to long-acting narcotic analgesia for the treatment of severe, progressive, cancer-related pain.
Methadone is another effective long-acting narcotic that is comparable in cost and efficacy to morphine and, therefore, would be an appropriate cost-effective alternative.
- Patients with progressive pain that ceases to respond to short-term pain management may require high-dose, escalating, long-acting narcotic analgesia.
Correct answer: D. Transthoracic echocardiography.
The most important predisposing risk factor for acute aortic dissection in older patients is hypertension. In the International Registry of Acute Aortic Dissection (IRAD), 72% of patients had a history of hypertension, but only 34% of those younger than 40 years. Bicuspid aortic valve was more common in younger patients. In patients with Marfan's syndrome, 50% of those younger than 40 years had a family history of aortic dissection compared with 2% in older patients. Pain is also quite common, with only 6% of patients in IRAD having painless dissection. A history of diabetes mellitus, aortic aneurysm or cardiovascular surgery was more common in patients with silent dissection, along with a slight increase in age. Syncope occurs in a small minority of cases, with an increased risk of tamponade and stroke, as well as a worse outcome.
The evaluation of patients with suspected thoracic aortic aneurysm or dissection includes chest CT with contrast, contrast-enhanced aortic MR angiography and transesophageal echocardiography. Although chest CT without contrast may be acceptable for detecting an aortic aneurysm, it has a low sensitivity for aortic dissection. Chest radiographs have a low sensitivity and low specificity for aortic dissection. Although gadolinium contrast is not nephrotoxic, a chest MRI or contrast-enhanced aortic MR angiography would be relatively contraindicated in this patient because he has an older pacemaker. Transesophageal echocardiography is the most appropriate imaging and can safely be performed in the emergency department for patients with suspected acute aortic dissection.
- Chest CT scan with contrast is indicated to detect acute aortic dissection.
- In patients at risk for radiocontrast nephropathy, transesophageal echocardiography is the test of choice for possible aortic dissection.
Correct answer: C. Aortic transection.
The patient's normal blood pressure, absence of rib notching on chest radiograph and presence of back pain make aortic coarctation an unlikely diagnosis. His young age, absence of cardiovascular risk factors, normal chest radiograph and absence of any sign of peripheral vascular compromise or aortic regurgitation make dissection an unlikely diagnosis. A penetrating atherosclerotic ulcer is an ulcer-like projection into an aortic intramural hematoma. Progression of the underlying process (i.e., aortic rupture, hematoma expansion or dissection) is much more likely in the presence of a penetrating ulcer. Although a penetrating atherosclerotic ulcer cannot be clinically distinguished from aortic dissection, it is an unlikely diagnosis in this patient for the same reasons that dissection is unlikely. There is also no history to suggest a major systemic illness such as Takayasu's arteritis (which usually afflicts young women of Japanese descent). Aortic transection (contained rupture, usually at the isthmus/immediately distal to the take-off of the left subclavian artery) can occur after rapid deceleration injuries such as motor vehicle accidents or a multistory fall. For those with leakage, rapid death is common, but the transection may be contained, resulting in a pseudoaneurysm (lacking in aortic wall components). Such contained ruptures/pseudoaneurysms are often saccular and may remain undetected and asymptomatic for years, ultimately presenting with pain suggestive of aortic dissection or even spontaneous rupture. They can be diagnosed with both thoracic CT scan and thoracic MR imaging with urgent repair indicated in surgical candidates.
- A history of rapid deceleration is a risk factor for aortic trauma, including dissection and transection.
- Complications of aortic transection may present after a prolonged latency.
- Physical examination in patients with aortic transection may be normal.
Correct answer: C. Aortic dissection.
There are several possible causes of acute severe chest pain in a pregnant woman. However, in this patient with musculoskeletal findings suggestive of Marfan syndrome, severe chest pain that radiates to her back, a new diastolic murmur, and a nonspecific electrocardiogram, the possibility of aortic dissection should be high on the differential diagnosis. Women with Marfan syndrome are at an increased risk of aortic dissection during pregnancy. Even in women without Marfan syndrome, the aortic root dilates by a few millimeters and the compliance of the arterial wall increases during pregnancy, most likely in response to hormonal changes. The increased risk of dissection in Marfan patients is due to the combination of these normal changes in the vessel wall, abnormal connective tissue microfibrils due to the fibrillin defect, and the increased aortic mechanical stress due to the higher output of pregnancy.
There is an increased risk of deep venous thrombosis and pulmonary embolism in pregnancy, but this patient has no evidence of leg swelling. d-dimer levels may be elevated during normal pregnancy and thus are less specific for the diagnosis of pulmonary embolism during pregnancy. Acute myocardial infarction due to spontaneous coronary artery dissection may occur during pregnancy even in the absence of atherosclerosis, but typical electrocardiographic changes would be present. Costochondritis is a diagnosis of exclusion and is associated with localized chest wall tenderness over the costochondral joints. Pericarditis is not associated with pregnancy per se, but could occur in a pregnant woman. The diagnosis of pericarditis is based on typical symptoms, a pericardial rub, and ST elevation on electrocardiogram, none of which are present in this case.
- Women with Marfan syndrome are at increased risk of aortic dissection during pregnancy.
- Aortic dissection should be considered in the differential diagnosis of chest pain in pregnancy.
Correct answer: C. Aortic dissection.
This patient's clinical presentation is consistent with cardiac tamponade resulting from aortic dissection. This patient has hypotension with tachycardia refractory to volume resuscitation and vasopressors after presenting with severe chest pain. Of importance, physical examination reveals distended jugular veins, elevated pulsus paradoxus, and an unremarkable lung examination. This constellation of signs should always raise the possibility of cardiac tamponade but is by no means pathognomonic. A massive pulmonary embolus, large acute myocardial infarction, or sepsis could account for refractory hypotension. However, an elevated pulsus paradoxus would be unexpected in these entities. Pulsus paradoxus is an important physical examination finding to assess for in virtually all patients who present without an obvious cause of hypotension. The blood pressure difference in the upper extremities coupled with a widened mediastinum on chest radiograph is consistent with an acute aortic dissection. Sepsis and bacterial pericarditis are unlikely to present acutely with a prodrome of merely three hours of chest pain in an otherwise healthy 49-year-old man.
- Aortic dissection with rupture into the pericardium presents with chest pain, refractory hypotension and elevated pulsus paradoxus and requires urgent recognition and therapy.
- A pulse pressure discrepancy between upper extremities in a patient presenting with chest pain should raise the diagnosis of aortic dissection.