While pitching batting practice, Uecker suffered a pain in his back so severe that he had to lie down. The team doctor immediately ordered an advanced scan.

"The MRI scan looked like I had swallowed a cantaloupe," Uecker recalled. "It was an abdominal aortic aneurysm. I was shocked because, except for the back pain, I felt good."

Uecker's experience is typical, according to vascular disease experts. Most aneurysms, or bulges in the arterial wall, cause no symptoms, although some patients may be aware of abnormal pulsation in the mid-abdomen.

Simple exams using a common technique called Doppler ultrasound can help physicians detect and monitor an abdominal aortic aneurysm. Like a balloon, a weakened aorta enlarges slowly at first from the pressure within, but the larger the bulge becomes, the more rapidly it grows until it eventually bursts.

Fortunately, advances in medicine now allow doctors to surgically repair large aneurysms and prevent a life-threatening rupture. Uecker's procedure was successful, and today he considers himself cured.

Approximately 20 percent of AAA patients have a close relative with the condition. Adults over 60--especially men and smokers--also have an increased risk.