What Is an Abdominal Aortic Aneurysm?
Abdominal aortic aneurysms (AAAs) are abnormal enlargements of the aorta — the largest blood vessel in your abdomen. An aneurysm is diagnosed when the aorta expands to at least one and a half times its normal size. Many people have no symptoms and don’t know they have one. In women, AAAs are often discovered incidentally during abdominal or pelvic imaging, or during screening prompted by a family history of aneurysm.
How Do Aneurysms Change Over Time?
Aneurysms tend to grow gradually — typically 1 to 3 mm (less than a tenth of an inch) per year. This growth may be slightly faster in women than in men. [1] Regular imaging with ultrasound or CT scans is used to monitor growth over time.
When an aneurysm is small and not causing problems, it is generally watched rather than treated. However, if it grows too large or the vessel wall becomes too weak, rupture can occur — causing sudden, life-threatening internal bleeding. When AAAs reach a certain size, preventive surgery is recommended before rupture has a chance to happen.
Yet the clinical guidelines used to decide when to operate were developed almost entirely from research on men, leaving a critical evidence gap for women.
Why Is AAA More Dangerous for Women?
The best size at which to repair an AAA to prevent rupture in women is not yet known.
At any given aneurysm size, women are more likely to experience a rupture than men. Historically, women were also less likely to be offered repair — whether for an intact or ruptured aneurysm — and less likely to survive to hospital discharge after surgery. [2]
At AAA treatment sizes of 5.5 cm or greater, women with minimally invasive EVAR have longer hospital stays and higher chance of death compared to men. [3] This may suggest a need for women to have their aneurysm repair at a smaller size.
What Do Current Guidelines Say?
Around the world doctors do not have general agreement about the best size for repairing women’s aneurysms. In the United States. Current 2018 guidelines from the Society for Vascular Surgery (SVS) recommend AAA repair when women’s aneurysms are 5.0–5.4 cm, which is a slightly smallerer than is recommended in men (5.5 cm or above). However, the evidence supporting this lower threshold of 5.0 cm for women is limited — rated as a weak (Level 2) recommendation by the SVS. [4]
WARRIORS is investigating whether repair at an earlier threshold — between 4.0 and 5.4 cm — leads to better outcomes for women, and whether current guidelines should be updated to reflect this.
The WARRIORS trial will provide the rigorous, women-focused data for making the stronger, evidence-based recommendations that clinicians — and patients — want and need as they make decisions about the best treatment plan for smaller aneurysms in women.
References
[1] Ngai H, Olson S, Curci J, et al. A comparison of women and men with small abdominal aortic aneurysms. Br J Surg. 2025;112(9):znaf185.
[2] Katz DJ, Stanley JC, Zelenock GB. Gender differences in abdominal aortic aneurysm prevalence, treatment, and outcome. J Vasc Surg. 1997;25(3):561-8.
[3] Sidloff DA, Saratzis A, Sweeting MJ, et al. Sex differences in mortality after abdominal aortic aneurysm repair in the UK. Br J Surg. 2017;104(12):1656-1664.
[4] Chaikof EL, Dalman RL, Eskandari MK, et al. The Society for Vascular Surgery practice guidelines on the care of patients with an abdominal aortic aneurysm. J Vasc Surg. 2018;67(1):2-77.