AAA Risk Factors and Screening

Size cutoff for being called AAA = >3.0 cm in diameter (average size is ~2.0 cm, but normal ranges from 1.4 to 3.0 cm)
Risk Factors for Developing AAA:

• Advancing Age
• Smoking
• Male sex – 5x more likely to develop it than women, and women develop it on average 10 years later than men.
• Also: Atherosclerosis and Hypertension are risk factors.

Risk Factors for Rupture:

• Large diameter – if > 5.0 cm, the 5 year risk of rupture is 25-40%.  If < 4.0 cm, it is very unlikely to rupture in the next 5 years.
• Rate of expansion is a risk factor
• Female sex is actually a risk factor for rupture as well – for an AAA the size size, a woman is more at risk for rupture than a male.

Screening Guidelines – USPTF Recommendations:  A one time abdominal ultrasound (or CT) is recommended for men aged 65-75 who have any history of smoking.  There is little benefit to repeat screening if ultrasound is negative, and screening in women is not recommended.
If patients are found to have AAA, repeat surveillance frequency depends on the size:

• 4-5.4 cm – q6-12 months
• 3-4 cm – q2-3 years

Indications for Surgical Repair:

• Symptomatic AAA, regardless of size
• >5.5 cm in asymptomatic patients
• Rapid rate of expansion with >0.5 cm in 6 months

(Chanu Rhee MD, 5/16/11)