An abdominal aortic aneurysm is a balloon-like bulge in the main artery that runs through the belly. It usually grows slowly and silently, but when it stretches or leaks it sends unmistakable signals.

Deep, steady belly or back pain is the classic clue. It feels like a heavy, dull weight or throbbing ache that doesn’t go away with rest, antacids, or a change in position.

Pulsing lump may show up. You feel a rhythmic thump deep in your abdomen, especially when lying flat.

Tenderness to touch appears. Pressing on the belly hurts, even though there’s no bruise.

Fullness or early satiety can occur if the aneurysm pushes on the stomach.

Shortness of breath creeps in if the aneurysm is large enough to press on the diaphragm.

Late alarms include sudden, severe belly or back pain, a drop in blood pressure, or fainting—clues the vessel may be tearing or rupturing.