Several problems can arise within the<unk> , usually related to its obstruction. Opinions vary slightly on the maximum calibre of a normal<unk> , but 6mm is one accepted upper limit of normal with a further 1mm diameter allowed for each decade over 60 years. It normally gets slightly dilated after cholecystectomy, with upper limit (95% prediction interval) being about 10 mm after a few months. On abdominal ultrasonography, the<unk>  is most readily seen in the porta hepatis (where the<unk>  lies anterior to the portal vein and hepatic artery). The absence of Doppler signal distinguishes it from the portal vein and hepatic artery. File:Ultrasonography of<unk>  hepatic<unk> , labeled.Borderline of a dilated perihilar<unk> <unk> , measuring 8 mm. File:Ultrasound Scan ND 090551 0930550 cr.Dilatation of<unk>  due to Ampullary tumor. If obstructed by a gallstone, a condition called choledocholithiasis can result. In this obstructed state, the<unk>  is especially vulnerable to an infection called ascending cholangitis. One form of treatment is a cholecystenterostomy. Rare deformities of the<unk>  are cystic dilations (4 cm), choledochoceles (cystic dilation of the ampula of Vater (3–8 cm)), and biliary atresia.
Common bile duct
Portal vein
Large intestine
Small intestine
Album graecum
Esophagus
Megaduodenum
Preureteric vena cava