## Why "Ultrasound annually" is right The patient has an infrarenal AAA measuring 4.8 cm (between 4.0–4.9 cm). According to Bailey & Love 28e and standard surveillance protocols, aneurysms in the 4.0–4.9 cm range require **annual ultrasound surveillance**. The fact that the renal arteries (marked **D**) remain above and uninvolved by the aneurysm confirms this is a true infrarenal AAA and does not alter the surveillance strategy. Annual imaging allows detection of expansion (especially if > 0.5 cm in 6 months or > 1 cm/year), which would trigger earlier intervention. ## Why each distractor is wrong - **Ultrasound every 2–3 years**: This interval applies to aneurysms < 4 cm. At 4.8 cm, the patient requires more frequent surveillance to detect rapid expansion. - **Ultrasound every 6 months**: This interval is reserved for aneurysms 5.0–5.4 cm. At 4.8 cm, 6-monthly imaging is unnecessarily frequent and not cost-effective. - **Immediate surgical or endovascular repair**: Repair is indicated for aneurysms ≥ 5.5 cm in men or those expanding > 0.5 cm in 6 months. At 4.8 cm with no documented rapid expansion, this patient is not yet at the threshold for intervention. **High-Yield:** AAA surveillance by size: < 4 cm (q2–3 years), 4.0–4.9 cm (annual), 5.0–5.4 cm (q6 months), ≥ 5.5 cm (repair). [cite: Bailey & Love 28e Ch 53; Robbins 10e Ch 11]
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