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  • 1. Introduction
  • 2. Botox Preparation
  • 3. Anal Examination Under Anesthesia
  • 4. Botox Injection
  • 5. Final Inspection of Fissures
  • 6. Post-op Local Anesthetic
  • 7. Post-op Remarks
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Anal Examination Under Anesthesia and Botox Injection for Chronic Anal Fissures


Jennifer Shearer, MD; Brooke Gurland, MD, FACS
Stanford University School of Medicine

Main Text

Most individuals associate anal pain with hemorrhoids. However, there are many conditions that can cause anal pain and bleeding, and physical examination helps to differentiate between these diagnoses: anal fissures, hemorrhoids, or infections. An anal fissure is a superficial tear in the anoderm. Fissures are diagnosed clinically by history and physical exam with careful spreading of the anus and direct visualization of a break in the mucosa and exposed sphincter fibers. Increased tone of the internal anal sphincter can inhibit fissure healing by decreasing blood flow to the mucosa. Conservative management includes stool softeners and warm sitz baths to avoid traumatizing the fissure with hard stools and relaxing the sphincters with warm water. Topical nitrates or calcium channel blockers applied at the anal verge dilate and relax the internal sphincter muscle to promote healing. Alternatively, injection of Onobotulinumtoxin A into the fissure and intersphincteric groove paralyzes sphincter muscle, decreasing muscle spasm and supporting healing of the fissure. For individuals who fail these conservative therapies, lateral internal sphincterotomy is considered. This procedure involves dividing the internal sphincter muscles but carries a small risk of fecal incontinence. We present the case of young adult male with a history of a chronic anal fissure, who failed medical management. Posterior anal fissure was appreciated on exam and treated with Onobotulinumtoxin A injection for relaxation of anal sphincter.

An anal fissure is a shallow superficial tear in the anoderm distal to the dentate line.13 Fissures form secondary to trauma of the anal canal related to constipation, diarrhea, or injury.3 Fissures cause anal pain, spasms, and bleeding and are predominately (approximately 75%) located in the posterior midline.1 Fissures may be acute or chronic, defined as lasting greater than 6 weeks.1 The incidence of fissures is most common in young or middle-aged patients and equally likely between men and women.1 In the United States, over 250,000 new cases are diagnosed each year.3

Male in his 20s with a history of chronic posterior anal fissure with anal pain and bleeding. This patient was previously managed with conservative medical management, including topical calcium channel blocker and pelvic floor physical therapy for the prior two years. His bowel symptoms waxed and waned, initially improving with lifestyle modification, relaxation techniques, and topical creams. He presented with an acute exacerbation of anal fissure with increased pain and bleeding.

Anal fissures are visible separations of continuity of the anoderm evident on rectal exam. Chronic fissures may also exhibit hypertrophied anal papilla, an associated skin tag or exposure of the internal anal sphincter at the base of fissure.4 Increased sphincter tone may limit exam in the outpatient setting.1

The course of an anal fissure can create a positive feedback loop, exacerbating symptoms and leading to the chronicity of the lesion.2 For example, pain will increase anal sphincter tone which in term limits blood flow to the anal fissure. This limited blood flow thereby limits healing of the lesion and exacerbates pain and chronicity of the fissure.

Acute anal fissures can likely be managed with conservative, non-operative therapy.1,4 This course includes utilization of stool softeners, adequate hydration, and dietary fiber.3 These measures are curative for half of patients with acute anal fissures. Additional therapies for chronic fissures include sitz bathes, topic nitrates, or calcium channel blockers, which resolve half of chronic fissures.1,2,3 Levator relaxation techniques and pelvic floor physical therapy are also recommended when there is high pelvic floor tone.4 The goals of these therapies are to target the underlying pathology leading to fissure formation such as constipation, straining, or diarrhea and allow for healing via sphincter relaxation, which increases blood flow to the fissure.

Onobotulinumtoxin A injection is an option for patients who have failed conservative therapies.3 The toxin is reconstituted in a small volume of sterile saline. We use 1 cc of normal saline to reconstitute 100 units. Onobotulinumtoxin A is injected into the fissure and internal sphincter.4 This procedure can be performed in the office or in the operating room with sedation for patients experiencing severe anal pain. The concentration, dosage of injection, and specific location of injections are surgeon dependent. There is a paucity of high quality studies that describe technique and support effectiveness. The pathophysiology is that Onobotulinumtoxin A causes temporary paralysis of the internal anal sphincter, reduces in anal sphincter tone, and promotes healing by increasing blood flow to fissure.1 Complications of this procedure are low, but the following has been reported: fecal urgency and incontinence, hematoma, proctitis, and injection site infection.

Finally, operative management of refractory chronic anal fissures include lateral internal sphincterotomy (LIS), the radial exposure and division of the internal sphincter muscle, and anal dilation.2,4 While LIS has a greater than 90% success of resolving anal fissures, it has an increased incidence of incontinence relative to the procedures outlined above.1,2,3

Anal fissures found in atypical locations, such as the lateral, are worthy of special considerations including Crohn's disease.3,5 Patients with Crohn's disease should have optimized medical management of inflammation prior to considering procedural intervention of anorectal lesions.1,3 Patients who have anal sex may develop anal fissures secondary to sexually transmitted infections including chlamydia, gonorrhea, or syphilis.6 Patients with HIV are at increased risk for AIDS-related ulcers or ulcerating herpes simplex virus, which may be indistinguishable from an anal fissure.1,3 Non-healing lesions may also suggest a neoplastic process, which must be ruled out.

The patient was a young adult male with a history of chronic anal fissure with increased symptoms of pain and bleeding despite a prolonged course of conservative medical management. Patient received botulism toxin injection to reduce anal sphincter tone and promote healing of fissure. The Onobotulinumtoxin A was reconstituted by injecting 1 cc of injectable saline into the vial of 100 units. The 100 units was injected on either side of the fissure and in the intersphincteric groove on both the right and left sides for sphincter relaxation.

Patient positioning in either lithotomy or prone position provides excellent exposure to anorectal pathology, and in this video, we opted for lithotomy positioning with Yellofin stirrups. A pudendal block was performed for postoperative pain control by identifying the ischial tuberosities on the right and left side and injecting 0.25% bupivacaine medially to infiltrate the neurologic bundle. Typically, fissures are not sutured closed, but if the mucosal edges are retracted and scarred, then creating mucosal flaps and loosely approximating the edge can facilitate healing.

  • Onobotulinumtoxin A reconstituted in sterile saline. Dilution of 100 units in 1 cc of saline was used in this case.
  • Anoscopes in different sizes to facilitate visualization into the anal canal.

Nothing to disclose.

The patient referred to in this video article has given their informed consent to be filmed and is aware that information and images will be published online.


  1. Beaty JS, Shashidharan M. Anal fissure. Clin Colon Rectal Surg. 2016 Mar;29(1):30-7. doi:10.1055/s-0035-1570390.
  2. Ebinger SM, Hardt J, Warschkow R, et al. Operative and medical treatment of chronic anal fissures - a review and network meta-analysis of randomized controlled trials. J Gastroenterol. 2017 Jun;52(6):663-676. doi:10.1007/s00535-017-1335-0.
  3. Jahnny B, Ashurst JV. Anal fissures. [Updated 2021 Nov 21]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from:
  4. van Reijn-Baggen DA, Elzevier HW, Putter H, Pelger RCM, Han-Geurts IJM. Pelvic floor physical therapy in patients with chronic anal fissure: a randomized controlled trial. Tech Coloproctol. 2022 Jul;26(7):571-582. doi:10.1007/s10151-022-02618-9.
  5. Stewart DB, Gaertner W, Glasgow S, Migaly J, Feingold D, Steele SR. Clinical practice guideline for the management of anal fissures. Dis Colon Rectum. 2017 Jan;60(1):7-14. doi:10.1097/DCR.0000000000000735.
  6. Assi R, Hashim PW, Reddy VB, Einarsdottir H, Longo WE. Sexually transmitted infections of the anus and rectum. World J Gastroenterol. 2014 Nov 7;20(41):15262-8. doi:10.3748/wjg.v20.i41.15262.

Cite this article

Shearer J, Gurland B. Anal examination under anesthesia and Botox injection for chronic anal fissures. J Med Insight. 2023;2023(371). doi:10.24296/jomi/371.