# Abdominal Aortic Aneurysm Repair > Abdominal aortic aneurysm repair for NEET-SS Vascular Surgery: the 5.5 cm threshold, open repair, permissive hypotension in rupture and screening. - Canonical URL: https://prepelephant.com/topics/neet-ss/vascular-surgery/aortic-aneurysm-repair-ss - Exam / course: NEET-SS · Subject: Vascular Surgery - Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team - First published: 2026-10-02 - Last updated: 2026-10-02 - How to cite: "Abdominal Aortic Aneurysm Repair", PrepElephant, https://prepelephant.com/topics/neet-ss/vascular-surgery/aortic-aneurysm-repair-ss ## Direct answer Elective repair is offered once an abdominal aortic aneurysm reaches 5.5 cm in a man or 5.0 cm in a woman, grows faster than about 1 cm a year, or becomes tender — a symptomatic aneurysm is repaired whatever its diameter. Rupture announces itself with the classical triad of sudden abdominal or back pain, a pulsatile mass and hypotension; about half die before reaching hospital. Open repair replaces the aneurysmal segment with a Dacron tube or bifurcated graft through a transperitoneal or retroperitoneal approach; endovascular repair suits favourable anatomy and is a separate topic. Elective open repair in a fit patient carries mortality of roughly 2–5%, against perhaps a third of those who reach theatre after rupture — the entire rationale for finding these before the catastrophe. ## What you must remember - Thresholds of 5.5 cm in men and 5.0 cm in women come from the UKSAT and ADAM trials; smaller for symptomatic, tender or rapidly growing aneurysms and for familial disease. - Screening: one-time ultrasound for men aged 65–75 who have ever smoked (USPSTF), or all men at 65 in the UK programme; India has no national screening programme, so diagnosis is usually incidental. - Small aneurysms grow a few millimetres a year; typical surveillance is roughly annual from 4.0 cm and six-monthly from 4.5 cm. - Open technique: transperitoneal or left retroperitoneal exposure (the latter for hostile abdomens and reoperations), infrarenal clamping — higher when the neck fails — and tube or bifurcated inlay grafting. - Clamping raises afterload and can precipitate myocardial ischaemia; declamping causes hypotension and acidotic washout, so the anaesthetist is warned before release. - Specific complications: renal injury from suprarenal clamping, colonic ischaemia from interruption of inferior mesenteric and internal iliac flow (bloody diarrhoea — assess with flexible sigmoidoscopy), distal embolisation ("trash foot"), and late graft infection or aortoenteric fistula with herald bleeds. - Inflammatory aneurysms encase the ureters and duodenum; mycotic aneurysms require excision with in situ or extra-anatomic reconstruction plus prolonged antibiotics. - Rupture management: permissive hypotension (systolic near 90 mmHg), massive transfusion protocol and immediate theatre — no time-consuming CT in an unstable patient with a known aneurysm. ## Two patients, one aneurysm Consider first a fit 70-year-old with a 5.6 cm infrarenal aneurysm found on an ultrasound done for gallstones. The pathway is cardiac risk stratification, lung optimisation, then open versus endovascular decided by neck anatomy and life expectancy; a hostile neck in an unfit patient pushes toward fenestrated technology, not a standard stent graft. Now the second patient: a 75-year-old collapses with back pain, a pulsatile mass and a blood pressure of 80 systolic. Permissive hypotension keeps the fragile retroperitoneal clot intact — vigorous fluid resuscitation can pop it — while blood products are prepared and theatre is activated; if he is stable enough to reach CT quickly, the study confirms rupture and anatomy for a possible endovascular approach. On the table, control comes first with a supracoeliac clamp if needed, dropping to infrarenal once the neck is secured. The two paragraphs together are the screening argument: detection converts a catastrophe with greater than 50% mortality into a planned operation with 2–5%. ## How the exam frames it Examiners love the diameter question: why 5.5? Because UKSAT and ADAM found no survival benefit from repairing smaller aneurysms while operative risk persists — and why lower for women? Because women rupture at smaller diameters in observational datasets. The second favourite is the postoperative patient with bloody diarrhoea on day three: colonic ischaemia until sigmoidoscopy proves otherwise, from loss of inferior mesenteric and internal iliac collaterals. Third, the patient who reports a small volume of fresh rectal bleeding years after grafting: aortoenteric fistula until excluded — CT angiography and a plan for complex revision, not reassurance. Answers built on mechanism separate a pass from a commendation. ## Frequently asked questions ### At what diameter is elective repair indicated? 5.5 cm in men and 5.0 cm in women per current guidance, earlier for rapid growth beyond about 1 cm a year, tenderness or symptomatic aneurysm. ### Which patients should be screened for abdominal aortic aneurysm? Men aged 65–75 who have ever smoked (or all men at 65 in national programmes); India has no organised screening, so clinicians must image opportunistically in smokers and those with family history. ### What physiological consequences follow aortic clamping? Sudden afterload increase risking myocardial ischaemia, plus altered renal perfusion with high clamps; declamping then produces hypotension from venous pooling and acidotic washout. ### What is permissive hypotension in rupture? Deliberately accepting a systolic pressure near 90 mmHg until control, because over-resuscitation disrupts the contained retroperitoneal haematoma and re-bleeds it. ### How does colonic ischaemia present after repair? Bloody diarrhoea with abdominal distension or leucocytosis in the first days, assessed by flexible sigmoidoscopy; mild cases settle, transmural necrosis demands resection. ### When is open repair chosen over endovascular? When anatomy is hostile to a stent graft, when the patient is young and durable exclusion is valued, or with infective and inflammatory aneurysms where open reconstruction with in situ graft or flap may be preferable.