Spiral folds of cystic duct[2][1] (also known as the spiral mucosal folds,[3] spiral valves of Cina,[citation needed] Amussat valve, or Cina valves) are a series of crescenteric, spirally arranged mucosal folds[4][2] in the proximal part of[2] the cystic duct.
[2] The spiral valves are supported by underlying smooth muscle fibers.
[3] The presence of the spiral folds, in combination with the tortuosity of the cystic duct, makes endoscopic cannulation and catheterization of the cystic duct extremely difficult.
The valves of Cina are susceptible to lacerations and were once a serious obstacle to the surgical canalization, which has since been overcome by newer technologies.
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