Start

Acute anal fissure (<6–8 weeks)

Surgical therapy chronic anal fissure

Recurrent anal fissure after LIS

Surgical therapy

End

Hypotonic sphincter

Hypertonic sphincter

Anoplasty (Advancement or house flap)

Lateral internal sphincterotomy (LIS)

Recurrent fissure

Rule out alternative etiology

Repeat LIS on contralateral side

Fissurectomy with advancement flap

Anal manometry or TRUS to assess sphincter complex

Hypotonic or sphincter defect

Hypertonic

TRUS, Transrectal ultrasound.

Calcium-channel blockers (CCB)

Botulinum toxin (Botox) injection

Stool softener
Fiber
Sitz bath

Chronic anal fissure (>6–8 weeks)

Nitric oxide (NO) donors

Calcium-channel blockers (CCB)

Nitric oxide (NO) donors

Botulinum toxin (Botox) injection