Vanita Mahan, ARNP, DNP

A 60-year-old white man with a history of hyperlipidemia, hypertension, and anxiety presented with complaints of abdominal pain, localized to an area left of the umbilicus. He described the pain as constant and rated it 6 on a scale of 1 to 10. He said the pain had been present for longer than three weeks.

The man said he had been seen by another health care provider shortly after the pain began, but he did not think the provider took his complaint seriously. At that visit, antacids were prescribed, blood work was ordered, and the man was told to return if there was no improvement. He felt that because he was being treated for anxiety, the provider believed he was just imagining the pain.

At the current visit, the review of systems revealed additional complaints of shakiness and nausea without vomiting, with other findings unremarkable. The persistent pain did not seem related to eating, and the patient had no history of any surgeries that might help explain his current complaints. He had smoked a pack of cigarettes daily for 40 years and had a history of heavy alcohol use, although he denied having consumed any alcohol during the previous five years.

His prescribed medications included gemfibrozil 600 mg per day, hydrochlorothiazide 25 mg each morning, and diazepam 5 mg twice daily, with an OTC antacid.

The patient’s recent laboratory results were normal; they included a complete blood count, comprehensive metabolic panel, liver enzyme levels, and a serum amylase level. The patient weighed 280 lb and his height was 5’10”; his BMI was 40. His temperature was 97.7°F, with a regular heart rate of 88 beats/min; blood pressure, 140/90 mm Hg; and respiratory rate, 18 breaths/min.

The patient did not appear to be in acute distress. A bruit was heard in the indicated area of pain. No mass was palpated, and the width of his aorta could not be determined because of his obesity. His physical exam was otherwise normal.

Abdominal ultrasonography (US) revealed a 5.5-cm abdominal aortic aneurysm (AAA), and the man was referred for immediate surgery. The aneurysm was repaired in an open abdominal procedure with a polyester prosthetic graft. The surgery was successful.

Discussion
AAA is a permanent bulging area of the aorta that exceeds 3.0 cm in diameter (see Figure 1). It is a potentially life-threatening condition due to the possibility of rupture. Often an aneurysm is asymptomatic until it ruptures, making this a difficult illness to diagnose.¹

Each year, an estimated 10,000 deaths result from a ruptured AAA, making this condition the 14th leading cause of death in the United States.^2,3 Incidence of AAA appears to have increased over the past two decades. Causes for this may include the aging of the US population, an increase in the number of smokers, and a trend toward diets that are higher in fat.

Prognosis among patients with AAA can be improved with increased awareness of the disease among health care providers, earlier detection of AAAs at risk for rupture, and timely, effective interventions.

Symptomatology
In about one-third of patients with a ruptured AAA, a clinical triad of symptoms is present: abdominal and/or back pain, a pulsatile abdominal mass, and hypotension.^4,5 In these cases, according to the American College of Cardiology/American Heart Association (ACC/AHA),⁴ immediate surgical evaluation is indicated.

Prior to the rupture of an AAA, the patient may feel a pulsing sensation in the abdomen or may experience no symptoms at all. Some patients report vague complaints, such as back, flank, groin, or abdominal pain. Syncope may be the chief complaint as the aneurysm expands, so it is important for primary care providers to be alert to progressive symptoms, including this signal that an aneurysm may exist and may be expanding.⁶

Pain may also be abrupt and severe in the lower abdomen and back, including tenderness in the area over the aneurysm. Shock can develop rapidly and symptoms such as cyanosis, mottling, altered mental status, tachycardia, and hypotension may be present.^1,4

Since symptoms may be vague, the differential diagnosis can be broad (see Table 1^4,7,8), necessitating a detailed patient history and a careful physical examination. In an elderly patient, low back pain should be evaluated for AAA.⁹ In addition, acute abdominal pain in a patient older than 50 should be presumed to be a ruptured AAA.⁸

Risk Factors
A clinician should be familiar with the risk factors for AAA so that diagnosis can be made before a rupture occurs. Male gender and age greater than 65 are important risk factors for AAA, but one of the most important environmental risks is cigarette smoking.^9,10 Current smokers are more than seven times more likely than nonsmokers to have an aneurysm.¹⁰ Atherosclerosis, which weakens the wall of the aorta, is also believed to contribute to the risk for AAA.¹¹

Other contributing factors include hypertension, chronic obstructive pulmonary disease, hyperlipidemia, and family history. Chronic infection, inflammatory illnesses, and connective tissue disorders (eg, Marfan syndrome) can also increase the risk for aneurysm. Less frequent causes of AAA are trauma and infectious diseases, such as syphilis.^1,12

In 85% of patients with femoral aneurysms, AAA has been found to coexist, as it has in 62% of patients with popliteal aneurysms. Patients previously diagnosed with these conditions should be screened for AAA.4,^13,14

Diagnosis
An abdominal bruit or a pulsating mass may be found on palpation, but the sensitivity for detection of AAA is related to its size. An aneurysm greater than 5.0 cm has an 82% chance of detection by palpation.¹⁵ To assess for the presence of an abdominal aneurysm, the examiner should press the midline between the xiphoid and umbilicus bimanually, firmly but gently.¹² There is no evidence to suggest that palpating the abdomen can cause an aneurysm to rupture.

The most useful tests for diagnosis of AAA are US, CT, and MRI.⁶ US is the simplest and least costly of these diagnostic procedures; it is noninvasive and has a sensitivity of 95% and specificity of nearly 100%. Bedside US can provide a rapid diagnosis in an unstable patient.¹⁶

CT is nearly 100% effective in diagnosing AAA and is usually used to help decide on appropriate treatment, as it can determine the size and shape of the aneurysm.¹⁷ However, CT should not be used for unstable patients.

MRI is useful in diagnosing AAA, but it is expensive, and inappropriate for unstable patients. Currently, conventional aortography is rarely used for preoperative assessment but may still be used for placement of endovascular devices or in patients with renal complications.^1,12

Screening Recommendations
The US Preventive Services Task Force (USPSTF) recommends that all men ages 65 to 74 who have a lifelong history of smoking at least 100 cigarettes should be screened for AAA with abdominal US.^3,18 Screening is not recommended for those younger than 65 who have never smoked, but this decision must be individualized to the patient, with other risk factors considered.

The ACC/AHA4 advises that men whose parents or siblings have a history of AAA and who are older than 60 should undergo physical examination and screening US for AAA. In addition, patients with a small AAA should receive US surveillance until the aneurysm reaches 5.5 cm in diameter; survival has not been shown to improve if an AAA is repaired before it reaches this size.^1,2,19 In consideration of increased comorbidities and decreased life expectancy, screening is not recommended for men older than 75, but this too should be determined individually.³

Screening for women is not recommended by the USPSTF.^3,18 The document states that the prevalence of large AAAs in women is low and that screening may lead to an increased number of unnecessary surgeries with associated morbidity and mortality. Clinical judgment must be used in making this decision, however, as several studies have shown that women have an AAA rupture rate that is three times higher than that in men; they also have an increased in-hospital mortality rate when rupture does occur. Thus, women are less likely to experience AAA but have a worse prognosis when AAA does develop.^20-22

Management
The size of an AAA is the most important predictor of rupture. According to the ACC/AHA,⁴ the associated risk for rupture is about 20% for aneurysms that measure 5.0 cm in diameter, 40% for those measuring at least 6.0 cm, and at least 50% for aneurysms exceeding 7.0 cm.^4,23,24 Regarding surveillance of known aneurysms, it is recommended that a patient with an aneurysm smaller than 3.0 cm in diameter requires no further testing. If an AAA measures 3.0 to 4.0 cm, US should be performed yearly; if it is 4.0 to 4.9 cm, US should be performed every six months.^4,25

If an identified AAA is larger than 4.5 cm, or if any segment of the aorta is more than 1.5 times the diameter of an adjacent section, referral to a vascular surgeon for further evaluation is indicated. The vascular surgeon should be consulted immediately regarding a symptomatic patient with an AAA, or one with an aneurysm that measures 5.5 cm or larger, as the risk for rupture is high.^4,26

Preventing rupture of an AAA is the primary aim in management. Beta-blockers may be used to reduce systolic hypertension in cardiac patients, thus slowing the rate of expansion in those with aortic aneurysms. Patients with a known AAA should undergo frequent monitoring for blood pressure and lipid levels and be advised to stop smoking. Smoking cessation interventions such as behavior modification, nicotine replacement, or bupropion should be offered.^27,28 

There is evidence that statin use may reduce the size of aneurysms, even in patients without hypercholesterolemia, possibly due to statins’ anti-inflammatory properties.^22,29 ACE inhibitors may also be beneficial in reducing AAA growth and in lowering blood pressure. Antiplatelet medications are important in general cardiovascular risk reduction in the patient with AAA. Aspirin is the drug of choice.^27,29

Surgical Repair
AAAs are usually repaired by one of two types of surgery: endovascular repair (EVR) or open surgery. Open surgical repair, the more traditional method, involves an incision into the abdomen from the breastbone to below the navel. The weakened area is replaced with a graft made of synthetic material. Open repair of an intact AAA, performed under general anesthesia, takes from three to six hours, and the patient must be hospitalized for five to eight days.³⁰

In EVR, the patient is given epidural anesthesia and an incision is made in the right groin, allowing a synthetic stent graft to be threaded by way of a catheter through the femoral artery to repair the lesion (see Figure 2). EVR generally takes two to five hours, followed by a two- to five-day hospital stay. EVR is usually recommended for patients who are at high risk for complications from open operations because of severe cardiopulmonary disease or other risk factors, such as advanced age, morbid obesity, or a history of multiple abdominal operations.^1,2,4,19

Prognosis
Patients with a ruptured AAA have a survival rate of less than 50%, with most deaths occurring before surgical repair has been attempted.^3,31 In patients with kidney failure resulting from AAA (whether ruptured or unruptured, an AAA can disrupt renal blood flow), the chance for survival is poor. By contrast, the risk for death during surgical graft repair of an AAA is only about 2% to 8%.^1,12

In a systematic review, EVR was associated with a lower 30-day mortality rate compared with open surgical repair (1.6% vs 4.7%, respectively), but this reduction did not persist over two years’ follow-up; neither did EVR improve overall survival or quality of life, compared with open surgery.¹ Additionally, EVR requires periodic imaging throughout the patient’s life, which is associated with more reinterventions.^1,19

Patient Education
Clinicians should encourage all patients to stop smoking, follow a low-cholesterol diet, control hypertension, and exercise regularly to lower the risk for AAAs. Screening recommendations should be explained to patients at risk, as should the signs and symptoms of an aneurysm. These patients should be instructed to call their health care provider immediately if they suspect a problem.

Conclusion
The incidence of AAA is increasing, and primary care providers must be prepared to act promptly in any case of suspected AAA to ensure a safe outcome. For aneurysms measuring greater than 5.5 cm in diameter, open or endovascular surgical repair should be considered. Patients with smaller aneurysms or contraindications for surgery should receive careful medical management and education to reduce the risks of AAA expansion leading to possible rupture.

A 60-year-old white man with a history of hyperlipidemia, hypertension, and anxiety presented with complaints of abdominal pain, localized to an area left of the umbilicus. He described the pain as constant and rated it 6 on a scale of 1 to 10. He said the pain had been present for longer than three weeks.

The man said he had been seen by another health care provider shortly after the pain began, but he did not think the provider took his complaint seriously. At that visit, antacids were prescribed, blood work was ordered, and the man was told to return if there was no improvement. He felt that because he was being treated for anxiety, the provider believed he was just imagining the pain.

At the current visit, the review of systems revealed additional complaints of shakiness and nausea without vomiting, with other findings unremarkable. The persistent pain did not seem related to eating, and the patient had no history of any surgeries that might help explain his current complaints. He had smoked a pack of cigarettes daily for 40 years and had a history of heavy alcohol use, although he denied having consumed any alcohol during the previous five years.

His prescribed medications included gemfibrozil 600 mg per day, hydrochlorothiazide 25 mg each morning, and diazepam 5 mg twice daily, with an OTC antacid.

The patient’s recent laboratory results were normal; they included a complete blood count, comprehensive metabolic panel, liver enzyme levels, and a serum amylase level. The patient weighed 280 lb and his height was 5’10”; his BMI was 40. His temperature was 97.7°F, with a regular heart rate of 88 beats/min; blood pressure, 140/90 mm Hg; and respiratory rate, 18 breaths/min.

The patient did not appear to be in acute distress. A bruit was heard in the indicated area of pain. No mass was palpated, and the width of his aorta could not be determined because of his obesity. His physical exam was otherwise normal.

Abdominal ultrasonography (US) revealed a 5.5-cm abdominal aortic aneurysm (AAA), and the man was referred for immediate surgery. The aneurysm was repaired in an open abdominal procedure with a polyester prosthetic graft. The surgery was successful.

Discussion
AAA is a permanent bulging area of the aorta that exceeds 3.0 cm in diameter (see Figure 1). It is a potentially life-threatening condition due to the possibility of rupture. Often an aneurysm is asymptomatic until it ruptures, making this a difficult illness to diagnose.¹

Each year, an estimated 10,000 deaths result from a ruptured AAA, making this condition the 14th leading cause of death in the United States.^2,3 Incidence of AAA appears to have increased over the past two decades. Causes for this may include the aging of the US population, an increase in the number of smokers, and a trend toward diets that are higher in fat.

Prognosis among patients with AAA can be improved with increased awareness of the disease among health care providers, earlier detection of AAAs at risk for rupture, and timely, effective interventions.

Symptomatology
In about one-third of patients with a ruptured AAA, a clinical triad of symptoms is present: abdominal and/or back pain, a pulsatile abdominal mass, and hypotension.^4,5 In these cases, according to the American College of Cardiology/American Heart Association (ACC/AHA),⁴ immediate surgical evaluation is indicated.

Prior to the rupture of an AAA, the patient may feel a pulsing sensation in the abdomen or may experience no symptoms at all. Some patients report vague complaints, such as back, flank, groin, or abdominal pain. Syncope may be the chief complaint as the aneurysm expands, so it is important for primary care providers to be alert to progressive symptoms, including this signal that an aneurysm may exist and may be expanding.⁶

Pain may also be abrupt and severe in the lower abdomen and back, including tenderness in the area over the aneurysm. Shock can develop rapidly and symptoms such as cyanosis, mottling, altered mental status, tachycardia, and hypotension may be present.^1,4

Since symptoms may be vague, the differential diagnosis can be broad (see Table 1^4,7,8), necessitating a detailed patient history and a careful physical examination. In an elderly patient, low back pain should be evaluated for AAA.⁹ In addition, acute abdominal pain in a patient older than 50 should be presumed to be a ruptured AAA.⁸

Risk Factors
A clinician should be familiar with the risk factors for AAA so that diagnosis can be made before a rupture occurs. Male gender and age greater than 65 are important risk factors for AAA, but one of the most important environmental risks is cigarette smoking.^9,10 Current smokers are more than seven times more likely than nonsmokers to have an aneurysm.¹⁰ Atherosclerosis, which weakens the wall of the aorta, is also believed to contribute to the risk for AAA.¹¹

Other contributing factors include hypertension, chronic obstructive pulmonary disease, hyperlipidemia, and family history. Chronic infection, inflammatory illnesses, and connective tissue disorders (eg, Marfan syndrome) can also increase the risk for aneurysm. Less frequent causes of AAA are trauma and infectious diseases, such as syphilis.^1,12

In 85% of patients with femoral aneurysms, AAA has been found to coexist, as it has in 62% of patients with popliteal aneurysms. Patients previously diagnosed with these conditions should be screened for AAA.4,^13,14

Diagnosis
An abdominal bruit or a pulsating mass may be found on palpation, but the sensitivity for detection of AAA is related to its size. An aneurysm greater than 5.0 cm has an 82% chance of detection by palpation.¹⁵ To assess for the presence of an abdominal aneurysm, the examiner should press the midline between the xiphoid and umbilicus bimanually, firmly but gently.¹² There is no evidence to suggest that palpating the abdomen can cause an aneurysm to rupture.

The most useful tests for diagnosis of AAA are US, CT, and MRI.⁶ US is the simplest and least costly of these diagnostic procedures; it is noninvasive and has a sensitivity of 95% and specificity of nearly 100%. Bedside US can provide a rapid diagnosis in an unstable patient.¹⁶

CT is nearly 100% effective in diagnosing AAA and is usually used to help decide on appropriate treatment, as it can determine the size and shape of the aneurysm.¹⁷ However, CT should not be used for unstable patients.

MRI is useful in diagnosing AAA, but it is expensive, and inappropriate for unstable patients. Currently, conventional aortography is rarely used for preoperative assessment but may still be used for placement of endovascular devices or in patients with renal complications.^1,12

Screening Recommendations
The US Preventive Services Task Force (USPSTF) recommends that all men ages 65 to 74 who have a lifelong history of smoking at least 100 cigarettes should be screened for AAA with abdominal US.^3,18 Screening is not recommended for those younger than 65 who have never smoked, but this decision must be individualized to the patient, with other risk factors considered.

The ACC/AHA4 advises that men whose parents or siblings have a history of AAA and who are older than 60 should undergo physical examination and screening US for AAA. In addition, patients with a small AAA should receive US surveillance until the aneurysm reaches 5.5 cm in diameter; survival has not been shown to improve if an AAA is repaired before it reaches this size.^1,2,19 In consideration of increased comorbidities and decreased life expectancy, screening is not recommended for men older than 75, but this too should be determined individually.³

Screening for women is not recommended by the USPSTF.^3,18 The document states that the prevalence of large AAAs in women is low and that screening may lead to an increased number of unnecessary surgeries with associated morbidity and mortality. Clinical judgment must be used in making this decision, however, as several studies have shown that women have an AAA rupture rate that is three times higher than that in men; they also have an increased in-hospital mortality rate when rupture does occur. Thus, women are less likely to experience AAA but have a worse prognosis when AAA does develop.^20-22

Management
The size of an AAA is the most important predictor of rupture. According to the ACC/AHA,⁴ the associated risk for rupture is about 20% for aneurysms that measure 5.0 cm in diameter, 40% for those measuring at least 6.0 cm, and at least 50% for aneurysms exceeding 7.0 cm.^4,23,24 Regarding surveillance of known aneurysms, it is recommended that a patient with an aneurysm smaller than 3.0 cm in diameter requires no further testing. If an AAA measures 3.0 to 4.0 cm, US should be performed yearly; if it is 4.0 to 4.9 cm, US should be performed every six months.^4,25

If an identified AAA is larger than 4.5 cm, or if any segment of the aorta is more than 1.5 times the diameter of an adjacent section, referral to a vascular surgeon for further evaluation is indicated. The vascular surgeon should be consulted immediately regarding a symptomatic patient with an AAA, or one with an aneurysm that measures 5.5 cm or larger, as the risk for rupture is high.^4,26

Preventing rupture of an AAA is the primary aim in management. Beta-blockers may be used to reduce systolic hypertension in cardiac patients, thus slowing the rate of expansion in those with aortic aneurysms. Patients with a known AAA should undergo frequent monitoring for blood pressure and lipid levels and be advised to stop smoking. Smoking cessation interventions such as behavior modification, nicotine replacement, or bupropion should be offered.^27,28 

There is evidence that statin use may reduce the size of aneurysms, even in patients without hypercholesterolemia, possibly due to statins’ anti-inflammatory properties.^22,29 ACE inhibitors may also be beneficial in reducing AAA growth and in lowering blood pressure. Antiplatelet medications are important in general cardiovascular risk reduction in the patient with AAA. Aspirin is the drug of choice.^27,29

Surgical Repair
AAAs are usually repaired by one of two types of surgery: endovascular repair (EVR) or open surgery. Open surgical repair, the more traditional method, involves an incision into the abdomen from the breastbone to below the navel. The weakened area is replaced with a graft made of synthetic material. Open repair of an intact AAA, performed under general anesthesia, takes from three to six hours, and the patient must be hospitalized for five to eight days.³⁰

In EVR, the patient is given epidural anesthesia and an incision is made in the right groin, allowing a synthetic stent graft to be threaded by way of a catheter through the femoral artery to repair the lesion (see Figure 2). EVR generally takes two to five hours, followed by a two- to five-day hospital stay. EVR is usually recommended for patients who are at high risk for complications from open operations because of severe cardiopulmonary disease or other risk factors, such as advanced age, morbid obesity, or a history of multiple abdominal operations.^1,2,4,19

Prognosis
Patients with a ruptured AAA have a survival rate of less than 50%, with most deaths occurring before surgical repair has been attempted.^3,31 In patients with kidney failure resulting from AAA (whether ruptured or unruptured, an AAA can disrupt renal blood flow), the chance for survival is poor. By contrast, the risk for death during surgical graft repair of an AAA is only about 2% to 8%.^1,12

In a systematic review, EVR was associated with a lower 30-day mortality rate compared with open surgical repair (1.6% vs 4.7%, respectively), but this reduction did not persist over two years’ follow-up; neither did EVR improve overall survival or quality of life, compared with open surgery.¹ Additionally, EVR requires periodic imaging throughout the patient’s life, which is associated with more reinterventions.^1,19

Patient Education
Clinicians should encourage all patients to stop smoking, follow a low-cholesterol diet, control hypertension, and exercise regularly to lower the risk for AAAs. Screening recommendations should be explained to patients at risk, as should the signs and symptoms of an aneurysm. These patients should be instructed to call their health care provider immediately if they suspect a problem.

Conclusion
The incidence of AAA is increasing, and primary care providers must be prepared to act promptly in any case of suspected AAA to ensure a safe outcome. For aneurysms measuring greater than 5.5 cm in diameter, open or endovascular surgical repair should be considered. Patients with smaller aneurysms or contraindications for surgery should receive careful medical management and education to reduce the risks of AAA expansion leading to possible rupture.

A 60-year-old white man with a history of hyperlipidemia, hypertension, and anxiety presented with complaints of abdominal pain, localized to an area left of the umbilicus. He described the pain as constant and rated it 6 on a scale of 1 to 10. He said the pain had been present for longer than three weeks.

The man said he had been seen by another health care provider shortly after the pain began, but he did not think the provider took his complaint seriously. At that visit, antacids were prescribed, blood work was ordered, and the man was told to return if there was no improvement. He felt that because he was being treated for anxiety, the provider believed he was just imagining the pain.

At the current visit, the review of systems revealed additional complaints of shakiness and nausea without vomiting, with other findings unremarkable. The persistent pain did not seem related to eating, and the patient had no history of any surgeries that might help explain his current complaints. He had smoked a pack of cigarettes daily for 40 years and had a history of heavy alcohol use, although he denied having consumed any alcohol during the previous five years.

His prescribed medications included gemfibrozil 600 mg per day, hydrochlorothiazide 25 mg each morning, and diazepam 5 mg twice daily, with an OTC antacid.

The patient’s recent laboratory results were normal; they included a complete blood count, comprehensive metabolic panel, liver enzyme levels, and a serum amylase level. The patient weighed 280 lb and his height was 5’10”; his BMI was 40. His temperature was 97.7°F, with a regular heart rate of 88 beats/min; blood pressure, 140/90 mm Hg; and respiratory rate, 18 breaths/min.

The patient did not appear to be in acute distress. A bruit was heard in the indicated area of pain. No mass was palpated, and the width of his aorta could not be determined because of his obesity. His physical exam was otherwise normal.

Abdominal ultrasonography (US) revealed a 5.5-cm abdominal aortic aneurysm (AAA), and the man was referred for immediate surgery. The aneurysm was repaired in an open abdominal procedure with a polyester prosthetic graft. The surgery was successful.

Discussion
AAA is a permanent bulging area of the aorta that exceeds 3.0 cm in diameter (see Figure 1). It is a potentially life-threatening condition due to the possibility of rupture. Often an aneurysm is asymptomatic until it ruptures, making this a difficult illness to diagnose.¹

Each year, an estimated 10,000 deaths result from a ruptured AAA, making this condition the 14th leading cause of death in the United States.^2,3 Incidence of AAA appears to have increased over the past two decades. Causes for this may include the aging of the US population, an increase in the number of smokers, and a trend toward diets that are higher in fat.

Prognosis among patients with AAA can be improved with increased awareness of the disease among health care providers, earlier detection of AAAs at risk for rupture, and timely, effective interventions.

Symptomatology
In about one-third of patients with a ruptured AAA, a clinical triad of symptoms is present: abdominal and/or back pain, a pulsatile abdominal mass, and hypotension.^4,5 In these cases, according to the American College of Cardiology/American Heart Association (ACC/AHA),⁴ immediate surgical evaluation is indicated.

Prior to the rupture of an AAA, the patient may feel a pulsing sensation in the abdomen or may experience no symptoms at all. Some patients report vague complaints, such as back, flank, groin, or abdominal pain. Syncope may be the chief complaint as the aneurysm expands, so it is important for primary care providers to be alert to progressive symptoms, including this signal that an aneurysm may exist and may be expanding.⁶

Pain may also be abrupt and severe in the lower abdomen and back, including tenderness in the area over the aneurysm. Shock can develop rapidly and symptoms such as cyanosis, mottling, altered mental status, tachycardia, and hypotension may be present.^1,4

Since symptoms may be vague, the differential diagnosis can be broad (see Table 1^4,7,8), necessitating a detailed patient history and a careful physical examination. In an elderly patient, low back pain should be evaluated for AAA.⁹ In addition, acute abdominal pain in a patient older than 50 should be presumed to be a ruptured AAA.⁸

Risk Factors
A clinician should be familiar with the risk factors for AAA so that diagnosis can be made before a rupture occurs. Male gender and age greater than 65 are important risk factors for AAA, but one of the most important environmental risks is cigarette smoking.^9,10 Current smokers are more than seven times more likely than nonsmokers to have an aneurysm.¹⁰ Atherosclerosis, which weakens the wall of the aorta, is also believed to contribute to the risk for AAA.¹¹

Other contributing factors include hypertension, chronic obstructive pulmonary disease, hyperlipidemia, and family history. Chronic infection, inflammatory illnesses, and connective tissue disorders (eg, Marfan syndrome) can also increase the risk for aneurysm. Less frequent causes of AAA are trauma and infectious diseases, such as syphilis.^1,12

In 85% of patients with femoral aneurysms, AAA has been found to coexist, as it has in 62% of patients with popliteal aneurysms. Patients previously diagnosed with these conditions should be screened for AAA.4,^13,14

Diagnosis
An abdominal bruit or a pulsating mass may be found on palpation, but the sensitivity for detection of AAA is related to its size. An aneurysm greater than 5.0 cm has an 82% chance of detection by palpation.¹⁵ To assess for the presence of an abdominal aneurysm, the examiner should press the midline between the xiphoid and umbilicus bimanually, firmly but gently.¹² There is no evidence to suggest that palpating the abdomen can cause an aneurysm to rupture.

The most useful tests for diagnosis of AAA are US, CT, and MRI.⁶ US is the simplest and least costly of these diagnostic procedures; it is noninvasive and has a sensitivity of 95% and specificity of nearly 100%. Bedside US can provide a rapid diagnosis in an unstable patient.¹⁶

CT is nearly 100% effective in diagnosing AAA and is usually used to help decide on appropriate treatment, as it can determine the size and shape of the aneurysm.¹⁷ However, CT should not be used for unstable patients.

MRI is useful in diagnosing AAA, but it is expensive, and inappropriate for unstable patients. Currently, conventional aortography is rarely used for preoperative assessment but may still be used for placement of endovascular devices or in patients with renal complications.^1,12

Screening Recommendations
The US Preventive Services Task Force (USPSTF) recommends that all men ages 65 to 74 who have a lifelong history of smoking at least 100 cigarettes should be screened for AAA with abdominal US.^3,18 Screening is not recommended for those younger than 65 who have never smoked, but this decision must be individualized to the patient, with other risk factors considered.

The ACC/AHA4 advises that men whose parents or siblings have a history of AAA and who are older than 60 should undergo physical examination and screening US for AAA. In addition, patients with a small AAA should receive US surveillance until the aneurysm reaches 5.5 cm in diameter; survival has not been shown to improve if an AAA is repaired before it reaches this size.^1,2,19 In consideration of increased comorbidities and decreased life expectancy, screening is not recommended for men older than 75, but this too should be determined individually.³

Screening for women is not recommended by the USPSTF.^3,18 The document states that the prevalence of large AAAs in women is low and that screening may lead to an increased number of unnecessary surgeries with associated morbidity and mortality. Clinical judgment must be used in making this decision, however, as several studies have shown that women have an AAA rupture rate that is three times higher than that in men; they also have an increased in-hospital mortality rate when rupture does occur. Thus, women are less likely to experience AAA but have a worse prognosis when AAA does develop.^20-22

Management
The size of an AAA is the most important predictor of rupture. According to the ACC/AHA,⁴ the associated risk for rupture is about 20% for aneurysms that measure 5.0 cm in diameter, 40% for those measuring at least 6.0 cm, and at least 50% for aneurysms exceeding 7.0 cm.^4,23,24 Regarding surveillance of known aneurysms, it is recommended that a patient with an aneurysm smaller than 3.0 cm in diameter requires no further testing. If an AAA measures 3.0 to 4.0 cm, US should be performed yearly; if it is 4.0 to 4.9 cm, US should be performed every six months.^4,25

If an identified AAA is larger than 4.5 cm, or if any segment of the aorta is more than 1.5 times the diameter of an adjacent section, referral to a vascular surgeon for further evaluation is indicated. The vascular surgeon should be consulted immediately regarding a symptomatic patient with an AAA, or one with an aneurysm that measures 5.5 cm or larger, as the risk for rupture is high.^4,26

Preventing rupture of an AAA is the primary aim in management. Beta-blockers may be used to reduce systolic hypertension in cardiac patients, thus slowing the rate of expansion in those with aortic aneurysms. Patients with a known AAA should undergo frequent monitoring for blood pressure and lipid levels and be advised to stop smoking. Smoking cessation interventions such as behavior modification, nicotine replacement, or bupropion should be offered.^27,28 

There is evidence that statin use may reduce the size of aneurysms, even in patients without hypercholesterolemia, possibly due to statins’ anti-inflammatory properties.^22,29 ACE inhibitors may also be beneficial in reducing AAA growth and in lowering blood pressure. Antiplatelet medications are important in general cardiovascular risk reduction in the patient with AAA. Aspirin is the drug of choice.^27,29

Surgical Repair
AAAs are usually repaired by one of two types of surgery: endovascular repair (EVR) or open surgery. Open surgical repair, the more traditional method, involves an incision into the abdomen from the breastbone to below the navel. The weakened area is replaced with a graft made of synthetic material. Open repair of an intact AAA, performed under general anesthesia, takes from three to six hours, and the patient must be hospitalized for five to eight days.³⁰

In EVR, the patient is given epidural anesthesia and an incision is made in the right groin, allowing a synthetic stent graft to be threaded by way of a catheter through the femoral artery to repair the lesion (see Figure 2). EVR generally takes two to five hours, followed by a two- to five-day hospital stay. EVR is usually recommended for patients who are at high risk for complications from open operations because of severe cardiopulmonary disease or other risk factors, such as advanced age, morbid obesity, or a history of multiple abdominal operations.^1,2,4,19

Prognosis
Patients with a ruptured AAA have a survival rate of less than 50%, with most deaths occurring before surgical repair has been attempted.^3,31 In patients with kidney failure resulting from AAA (whether ruptured or unruptured, an AAA can disrupt renal blood flow), the chance for survival is poor. By contrast, the risk for death during surgical graft repair of an AAA is only about 2% to 8%.^1,12

In a systematic review, EVR was associated with a lower 30-day mortality rate compared with open surgical repair (1.6% vs 4.7%, respectively), but this reduction did not persist over two years’ follow-up; neither did EVR improve overall survival or quality of life, compared with open surgery.¹ Additionally, EVR requires periodic imaging throughout the patient’s life, which is associated with more reinterventions.^1,19

Patient Education
Clinicians should encourage all patients to stop smoking, follow a low-cholesterol diet, control hypertension, and exercise regularly to lower the risk for AAAs. Screening recommendations should be explained to patients at risk, as should the signs and symptoms of an aneurysm. These patients should be instructed to call their health care provider immediately if they suspect a problem.

Conclusion
The incidence of AAA is increasing, and primary care providers must be prepared to act promptly in any case of suspected AAA to ensure a safe outcome. For aneurysms measuring greater than 5.5 cm in diameter, open or endovascular surgical repair should be considered. Patients with smaller aneurysms or contraindications for surgery should receive careful medical management and education to reduce the risks of AAA expansion leading to possible rupture.