Screening for Abdominal Aortic Aneurysm is Most Important
For a 65-75 year-old man with a history of heavy smoking, one-time screening for abdominal aortic aneurysm (AAA) with ultrasound is the most important preventive screening, as it can reduce the risk of dying from a ruptured AAA by approximately 50%. 1
Why AAA Screening Takes Priority
Mortality Benefit is Substantial
- Men aged 65-75 who smoke or have ever smoked represent the highest-risk group for AAA, and the U.S. Preventive Services Task Force gives this screening a Grade B recommendation (moderate certainty of moderate net benefit), meaning the benefits clearly outweigh the harms for this specific population. 1, 2
- AAA is most common in older men who smoke or have ever smoked, and one-time screening with ultrasound followed by appropriate treatment reduces AAA-specific mortality by about half. 1, 2
- The risk of death from AAA rupture is as high as 81%, making early detection critical. 3
The Screening Test is Safe and Effective
- Ultrasound has 95% sensitivity and nearly 100% specificity for detecting AAA, is non-invasive, safe, and cost-effective. 2
- One-time ultrasound screening is sufficient, as there is negligible benefit to repeat screening if the initial aortic diameter is normal. 2
Comparison with Other Screening Options
Colon Cancer Screening
- While colon cancer screening is important for this age group, it applies broadly to all adults aged 50-75 regardless of smoking status, making it less specifically indicated by this patient's unique risk profile. [@general medical knowledge@]
Prostate Cancer Screening
- Prostate cancer screening remains controversial with shared decision-making recommended, and does not have the same clear mortality benefit as AAA screening in male smokers. [@general medical knowledge@]
Osteoporosis Screening
- Osteoporosis screening is primarily recommended for women and men with specific risk factors (not smoking alone), making it less relevant for this patient. [@general medical knowledge@]
Clinical Implementation
What Defines a Positive Screen
- AAA is defined as aortic diameter ≥3.0 cm, with surgical intervention typically recommended when diameter reaches ≥5.5 cm or if rapid growth (>0.5 cm in 6 months) occurs. 2, 4
Management Based on Results
- Normal aorta (<3.0 cm): No further AAA screening needed. 2, 4
- Small AAA (3.0-4.4 cm): Surveillance ultrasound every 12 months. 4
- Medium AAA (4.5-5.4 cm): Surveillance ultrasound every 6 months. 4
- Large AAA (≥5.5 cm): Refer for surgical evaluation (open repair or endovascular repair). 2, 4
Critical Risk Factor Modification
- Smoking cessation is the strongest modifiable risk factor for AAA expansion and rupture and must be addressed immediately. 4, 5
- Blood pressure control is essential, as hypertension is associated with increased AAA risk and expansion. 4, 6
Common Pitfalls to Avoid
- Don't delay screening: Most AAAs are asymptomatic until rupture, so waiting for symptoms is dangerous. 5, 6, 7
- Don't forget the "ever smoked" criterion: Even former smokers who quit decades ago still qualify for and benefit from screening. 1, 3
- Don't repeat screening unnecessarily: If the initial ultrasound shows a normal aorta, one-time screening is sufficient. 2
The answer is C. Abdominal aortic aneurysm.