Anal Fissures
Overview:
Common cause of anal pain and bleeding
Incidence is about 8%.
Cause:
Anal fissures typically start with a tear from trauma.
Cycle of recurring anal pain, tear, and bleeding, leading to a chronic anal fissure in as many as 40% of patients.
Lack of blood flow may contribute and the most common location of primary fissures is the posterior midline (at 6 o’clock position if lying on your back)
Diagnosis
Based on clinical history. Visualising the fissure is not necessary for diagnosis. A digital anal examination is almost never performed due to acute pain.
Differential Diagnoses
Haemorrhoids - Uncomplicated haemorrhoids typically do not cause pain
Perianal ulcers - Can be seen in Crohn’s Disease or STDs
Anal Fistula - Typically presents as a draining skin punctum with a hole that tracks down through the skin towards the anorectum.
Risk factors:
Most anal fissures are primary caused by local trauma such as
Constipation
Diarrhoea
Vaginal delivery
Anal sex
Secondary causes are due to an underlying disease such as
Crohn’s disease
Tuberculosis
Sarcoidosis
Cancers
Sexual Transmitted Infections such as HIV, Chlamydia or syphilis
Symptoms:
Acute anal fissures have symptoms for < 8 weeks. Chronic anal fissures last longer.
Anal pain present at rest
Exacerbated by defecation, often severe
Pain that intensifies with defecation often last hours after
Can be anal bleeding
Examination
Anal fissures are commonly present as longitudinal tears in the anus
An acute tear appears fresh like a superficial laceration, much like a paper cut
Chronic fissures have raised edges exposing the white horizontally fibres of the internal anal sphincter muscle at the base.
Management
Initial medical therapy is 4 to 8 weeks of
Increased fibre
Recommended intake 20g to 35g per day
Sitz bath 2 to 3 times daily
Sitting in warm water for 10 to 15 minutes
This stimulates blood flow to the perineum allowing it to heal
Stool softeners if constipated
Twice daily topical vasodilator
Glyceryl Trinitrate 0.4% or Nifedipine 0.2-0.3%.
Nifedipine needs to be compounded but has less side effects and can be used up to 4 times daily. One study showed healing rates for Nifedpine versus GTN were 89% versus 58% and fewer side effects at 5% versus 40%.
Topical anaesthetic agents don’t improve outcomes but can help pain short-term. It’s possible to get a compounding pharmacist to make a local anaesthetic and vasodilator combination.
If medical therapy fails then the next steps are either Botox injection or a lateral sphincterotomy.
Rates of success for surgery versus medicine were 96 vs 67% at 5 weeks and 100 versus 89% at 10 weeks. Both were combined with sitz baths and fibre-bulking agents. The downside to surgery was increased rates of faecal incontinence with over 15% of patients still having problems at 2 years post-surgery.
References
Pisaster brevispinus - Wikipedia
Medical Management of Anal Fissures - Up To Date
Surgical Management of Anal Fissures - Up To Date