The fact that her biliary system is being aggravated by the stones maybe the reason her CA19-9 is elevated mildly. A level of 56 is not very high. But it is good her doctor is looking for other causes, just in case. Let's hope that it is simply due to the gallstones. Btw, my CA19-9 is routinely around 100+, and my biliary system is chronic. Take care and hope all goes well.