Hi, How are you? Thanks for writing in to HCM. my name is Dr Suresh Raghavaiah. I am a Liver and pancreas surgeon and I hope to answer your question today. I am sorry to hear that you are suffering from gallstones and since you have not mentioned any symptoms, I take it that you have none. Gall stones can and sometimes do pass from the gall bladder (GB) into the bile duct and then into the intestine and are then passed out naturally. But this happens when the stone is very small and does not get stuck anywhere during its passage. During its journey from the gallbladder to the outside, the stone, depending on its size, can get stuck in multiple places and can cause serious, sometimes life threatening complications. The first site it can get lodged is the cystic duct (tube draining the gall bladder). This leads to engorgement of the GB and may lead to infection and pus formation in the GB. This will need emergency surgery and antibiotics to take care of. The second site it can get stuck is the common bile duct. Blockage of the bile duct less to jaundice and again infection can set in which can be very serious. This will need an endoscopy (ERCP) to retrieve the stone. The third and most dangerous site for it to get blocked is the lower end of the bile duct after it has joined the pancreatic duct (ampulla of Vater). this is the narrowest part the stone will encounter and hence one of the most common sites for the stone to lodge in. This is very dangerous because blockage of the pancreatic duct could potentially lead to life threatening pancreatitis and its complications. This will also need an ERCP to remove the stone. The final site where it can get blocked is the junction of the small intestine and large intestine. This happens ver rarely and can lead to intestinal obstruction. So in answer to your question, You would rather not have the 13mm son pass through the 3.4 mm bile duct. Please consult a surgeon immediately and consider having a laparoscopic cholecystectomy done. Hope this answer helped you and hope you start feeling better. Please do not hesitate to contact me for further details.