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Lateral Internal Sphincterotomy
Lateral internal sphincterotomy (LIS) is a surgical procedure used to treat chronic anal fissures by making a small incision in the internal anal sphincter. This reduces muscle tension, allowing the fissure to heal while improving blood flow to the area. LIS has a high success rate, though minor risks such as temporary incontinence may occur.
Lateral Sphincterotomy, separating skin from IAS muscle
Image Credit: Surgery E-learning, CC BY 3.0 <https://creativecommons.org/licenses/by/3.0>, via Wikimedia Commons
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