Diagnosis

Primary:
Has no clear underlying cause. There are two theories on causality:¹

1. Spasm and increased anal tone in response to pain from anal trauma (such as from passing hard stools). These lead to reduced blood flow and ischaemia, increased risk of tearing, and poor healing of a resulting fissure.

2. Internal anal sphincter spasms (IAS) due to a local lack of nitric oxide synthase, i.e. a lack of a group of enzymes needed for the production of nitric oxide, the main mediator of IAS relaxation.

Secondary:
Has a clear underlying cause, such as constipation, inflammatory bowel disease, sexually transmitted infection (such as HIV infection and AIDS), or colorectal cancer.

Clinical features of anal fissure include anal pain with defaecation (with or without bright red rectal bleeding) and anal spasm.¹

Signs and symptoms - How to spot a chronic anal fissure

Patient type
Chronic anal fissure can occur in all ages but are most common in people aged 15-40 years.^2,3 Chronic anal fissure is often seen in third trimester of pregnancy or in the post-partum period.^2,3

Bleeding
Chronic anal fissure can present bleeding on defaecation,^1,3 usually bright red with a small quantity on stool or toilet paper.²

Pain
Pain on defaecation is a common symptom of chronic anal fissure.^1,3 The pain can often be severe. The sharp pain associated with anal fissure is due to the fissure opening up when the bowels are opened, and has been described as “like passing broken glass”.³ The associated burning pain may last several hours.³

Appearance
External examination of the anus may reveal a linear split in the anal mucosa. Chronic anal fissure are wide and deep with muscle fibres visible in the base. The edges are often swollen, and a skin tag may be visible at the end of the fissure.¹