Ultrasound Screening of Abdominal Aortic Aneurysm: Diameter Measurement and Referral Criteria to a Surgeon
Research Methodology
The abdominal aorta is examined with a convex probe of 2–5 MHz, preferably on an empty stomach, along its entire length (proximal, middle, infrarenal segments, and bifurcation) in longitudinal and transverse sections. In case of gas interference, graded compression, patient rotation to the side, and lateral access through a parenchymal window are used.
Definition and Diameter Measurement
An abdominal aortic aneurysm (AAA) is an irreversible local enlargement. Definition: aortic diameter ≥3.0 cm or enlargement more than 1.5 times the reference (normal) diameter (Society for Vascular Surgery). Most AAAs are infrarenal.
The maximum diameter is measured perpendicular to the vessel axis using the outer-to-outer method according to SVS reporting standards. For comparability during follow-up, measurements are performed uniformly; the cardiac cycle contributes to size variability (ESVS 2024).
“Look Higher”: Suprarenal Section
According to AIUM, report elements include study status (positive/negative/indeterminate) and assessment of the suprarenal section. Threshold for the section above the celiac trunk: >3.9 cm in men / >3.1 cm in women (AIUM Practice Parameter, 2021, rev. 2025).
Surveillance Intervals
| AAA Diameter | Surveillance Interval |
|---|---|
| 3.0–4.9 cm | Usually annually (12 months for 4.0–4.9 cm, SVS) |
| 5.0–5.4 cm | Every 6 months (SVS) |
A small AAA (3.0–5.4 cm) is not an indication for surgery but for regular ultrasound surveillance with comparable measurement.
When to Refer to a Vascular Surgeon
Referral is indicated when the diameter reaches ≥5.5 cm (men) / >5.0 cm (women), rapid growth (>0.5 cm in 6 months), symptoms, or saccular form. The intervention threshold is 5.5 cm in men / 5.0 cm in women (Chaikof E.L. et al., SVS, 2018).
Symptomatic Aneurysm and Suspected Rupture
For patients with abdominal or back pain, ultrasound is recommended to identify AAA and assess other causes of pain. If an aneurysm is detected, CT aortography with intravenous contrast (if no contraindications) is performed to rule out rupture and plan surgery. In case of suspected rupture or symptomatic aneurysm (abdominal/back pain, pulsating mass, hypotension) — urgent hospitalization and CTA.
Risk Factor Modification
Smoking cessation and blood pressure control are recommended. Screening is indicated for individuals aged 65–75 with a history of smoking (SVS). High physical activity has a protective effect (RR 0.70) through blood pressure and lipid control.
Frequently asked questions
What method is used to measure the maximum aortic diameter?
Perpendicular to the vessel axis, using the outer-to-outer method according to the reporting standards of the Society for Vascular Surgery.
At what diameter is an AAA diagnosed?
≥3.0 cm or enlargement more than 1.5 times the reference (normal) diameter (SVS).
At what diameter should a patient be referred to a vascular surgeon?
At ≥5.5 cm in men / >5.0 cm in women, as well as with rapid growth >0.5 cm in 6 months, symptoms, or saccular form.
What is the frequency of ultrasound surveillance for small AAAs?
3.0–4.9 cm — usually annually (12 months for 4.0–4.9 cm); 5.0–5.4 cm — every 6 months (SVS).
What should be done if an aneurysm rupture is suspected?
This is an emergency: immediate hospitalization and CT aortography to rule out rupture and plan surgery.