How long will symptoms be present before a 10cm abdominal aortic aneurysm ruptures?

Varies - get fixed!: Symptoms can include back pain, abdominal pain from the streching and pressure inside the aneurysm to surrounding tissues, "blue toe" syndrome ( pregangrene & gangrene ) from material inside the aneurysn "breaking off" & going downstream with blockage of lower leg/foot arteries. A 10 CM aneurysm should not be taken lightly & should be repaired soon. If ruptured, death rate is around 90%.

Usually no symptoms: Most aneurysms do not give any symptoms until they rupture. A 10cm aneurysm has been present for many years. The normal aorta is about 2 cm, and aneurysms tend to grow about .4 cm/year, meaning about 16 years. A 10 cm aneurysm should be treated very urgently, as it is at very high risk of rupturing, and outcomes are worse when treating a ruptured aneurysm than when treating electively.

When will it burst?: Even after some symptoms are present an aneurysm that has "leaked" may stay contained. There is absolutely no way to say how long before it ruptures. Just as some aneurysms can rupture with no preceding symptoms at all.