What is the appropriate evaluation and initial management for a 74‑year‑old man with hypertension, hyperlipidemia, prediabetes, a left common iliac artery aneurysm and abdominal aortic ectasia who presents with abdominal bloating?

Evaluation and Management of Abdominal Bloating in a Patient with Iliac Artery Aneurysm

This patient requires urgent vascular imaging with CT angiography to assess his known left common iliac artery aneurysm and abdominal aortic ectasia, as abdominal bloating may represent aneurysm expansion or impending rupture, followed by systematic evaluation for gastrointestinal causes only after excluding vascular catastrophe.

Immediate Vascular Assessment

Why Vascular Evaluation Takes Priority

• Abdominal bloating can be a presenting symptom of aneurysm expansion or rupture, particularly in patients with known iliac artery aneurysms, where compressive symptoms may manifest as abdominal discomfort or bloating 1
• Common iliac artery aneurysms expand at a median rate of 0.29 cm/year, with hypertension (which this patient has) predicting faster expansion at 0.32 cm/year 1
• Rupture has been documented in iliac aneurysms as small as 3.8 cm, and 27% of ruptured iliac aneurysms present with iliocaval or ilioiliac fistulas that can cause abdominal symptoms 1
• Emergency repair of ruptured iliac aneurysms carries 27% mortality versus 1% for elective repair, making early detection of expansion critical 1

Required Imaging

• Obtain CT angiography of the abdomen and pelvis immediately to measure current aneurysm size, assess for rupture or leak, and evaluate the abdominal aortic ectasia 2
• CTA is rated 8/9 (usually appropriate) by the American College of Radiology for evaluating iliac artery disease and provides comprehensive assessment of aneurysm morphology 2
• If the iliac aneurysm has grown to ≥3.5 cm or shows saccular morphology, elective repair is indicated as no ruptures have been observed below 3.8 cm but risk increases substantially above this threshold 1, 3

Urgent Referral Criteria

• Refer immediately to vascular surgery if the aneurysm is ≥3.5 cm, has grown ≥0.5 cm in 6 months, or if symptoms suggest compression or rupture 1, 4
• Any abdominal, back, or flank pain attributable to the aneurysm mandates urgent vascular surgery referral within 24-48 hours regardless of size 4
• Endovascular repair is the preferred first-line treatment for anatomically suitable patients with iliac aneurysms, with 0% 30-day mortality for elective EVAR versus 4% for open repair 1

Gastrointestinal Evaluation (After Excluding Vascular Emergency)

Algorithmic Approach to Bloating

Once vascular catastrophe is excluded, proceed with systematic GI evaluation:

Step 1: Assess for Constipation

• Obtain abdominal X-ray (KUB) to evaluate for stool burden, as constipation is a common cause of bloating in elderly patients with cardiovascular risk factors 2
• If constipation is present, evaluate for pelvic floor dyssynergia with anorectal manometry 2

Step 2: Evaluate for Food Intolerance

• Trial 2-week dietary restriction of lactose and fructose, as these are the most common carbohydrate intolerances causing bloating (60% fructose, 51% lactose in DGBI patients) 2
• If symptoms persist, consider hydrogen breath testing with glucose or lactulose to diagnose carbohydrate malabsorption 2

Step 3: Screen for SIBO Risk Factors

• This patient has multiple SIBO risk factors: age 74, prediabetes, and potential gastroparesis from cardiovascular disease 2
• If dietary restriction fails and SIBO risk factors are present, perform hydrogen-based breath testing or consider empiric antibiotic trial 2
• Rifaximin is the most studied antibiotic but is expensive; systemically absorbed alternatives include amoxicillin or metronidazole 2

Step 4: Rule Out Structural Abnormalities

• If the vascular CT shows no GI pathology and symptoms persist, obtain complete blood count, comprehensive metabolic panel, and consider abdominal ultrasound to exclude hepatobiliary disease, ascites, or masses 2

Symptomatic Management

• Simethicone can be used for symptomatic relief of gas and bloating 5
• Consider low-FODMAP diet trial if carbohydrate intolerance is suspected but breath testing is unavailable 2
• Diaphragmatic breathing exercises and central neuromodulators may help if visceral hypersensitivity is contributing 2

Critical Risk Factor Management

Cardiovascular Risk Reduction

• Initiate or optimize statin therapy immediately, as this patient has atherosclerotic peripheral arterial disease evidenced by iliac aneurysm and aortic ectasia 3, 6
• Target blood pressure <130/80 mmHg, as hypertension accelerates aneurysm expansion rates 3, 6, 1
• Screen for coronary artery disease and other peripheral arterial disease, as patients with AAA/iliac aneurysms have significantly impaired 5-year survival 3

Prediabetes Management

• Optimize glycemic control, as diabetes is associated with faster aneurysm progression and increased SIBO risk 2

Common Pitfalls to Avoid

• Do not dismiss abdominal bloating as purely gastrointestinal in a patient with known vascular pathology—always exclude aneurysm expansion or rupture first 1
• Do not delay vascular imaging to pursue GI workup—the 27% mortality of emergency iliac aneurysm repair versus 1% elective repair makes early detection paramount 1
• Do not assume the iliac aneurysm is stable without recent imaging—expansion rate of 0.29-0.32 cm/year means significant growth can occur between surveillance intervals 1
• Do not overlook that 20-40% of patients with AAA have concurrent iliac aneurysms, and this patient's "abdominal aortic ectasia" may represent early AAA requiring surveillance 7