Hard stool in a constipated person sometimes leads to formation of a crack at the outer margin of anal canal. This is known as Anal Fissure or Fissure in ano. In Ayurveda Fissure is known as Parikartika and it's symptom include moderate to severe pain during the act of defecation.
In early stage Fissure can be cured by medicines and diet management but in chronic Fissure Surgery is often required. Kshar sutra treatment can cure Fissure with acceptable results.