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Anorectal disorders: haemorrhoids, fissure, abscess and fistula
Anorectal disorders are told apart by the type of pain and bleeding: painless bleeding — internal haemorrhoids; sharp pain on defecation with fresh blood — fissure; constant pain with swelling and fever — abscess, which is treated by drainage, not by antibiotics alone.
Why it matters in the exam
Anorectal questions almost always present a patient with pain, bleeding or swelling, and the exam tests whether you can identify the disorder from three details: is there pain, when does it occur, and where is the finding. Internal haemorrhoids bleed painlessly and are graded by the degree of prolapse, while a thrombosed external haemorrhoid causes sharp pain and a bluish lump. A typical fissure lies in the posterior midline; a fissure elsewhere should raise suspicion of Crohn's disease, infection or a tumour.
Candidates are also asked about the order of treatments: for haemorrhoids — fibre and fluids, then rubber band ligation, and excision for advanced grades or failure; for a fissure — conservative care and sphincter-relaxing drugs (topical nitrate or diltiazem) for about 6–8 weeks, then botulinum or lateral internal sphincterotomy (LIS). A perianal abscess is drained at once, and roughly a third of patients will develop a fistula. Questions also cover Goodsall's rule, a seton for a complex fistula, and anal cancer (linked to HPV), which is treated first with chemoradiation, not surgery.
Key points
- Painless bleeding — internal haemorrhoid; sharp pain on defecation — fissure; constant pain and fever — abscess.
- Haemorrhoids: fibre, rubber band ligation for grades I–III, excision for grades III–IV or failure.
- Fissure: nitrate or diltiazem for about 6–8 weeks; then LIS or botulinum.
- Abscess — immediate drainage; fistula — fistulotomy or seton depending on the tract.
- Squamous anal cancer — chemoradiation.
Summary table
| Disorder | Presentation | First treatment | When to operate |
|---|---|---|---|
| Internal haemorrhoids | Painless fresh bleeding; grades I–IV by prolapse | Fibre, fluids; rubber band ligation for grades I–III | Grades III–IV, or failed ligation — haemorrhoidectomy |
| Thrombosed external haemorrhoid | Sharp pain and a bluish lump at the anal verge | Within 72 hours — excision of the haemorrhoid; later conservative care | Excision when seen early |
| Fissure | Sharp pain on defecation and fresh blood; posterior midline | Fibre, sitz baths, topical nitrate or diltiazem for about 6–8 weeks | Chronic fissure after failed treatment — LIS or botulinum |
| Perianal abscess | Constant pain, swelling, fever | Immediate drainage; antibiotics only for cellulitis, diabetes or immunosuppression | Drainage is the operation |
| Fistula | Chronic discharge from an opening near the anus | Define the tract (examination, pelvic MRI) | Simple low fistula — fistulotomy; high or complex — seton |
| Anal cancer (squamous) | Mass, bleeding, pain; linked to HPV | Chemoradiation | Surgery only for failure or recurrence |
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Sources
- ASCRS Clinical Practice Guidelines for the Management of Hemorrhoids, 2018 — Office procedures and surgical treatment
- ASCRS Clinical Practice Guidelines for the Management of Anal Fissures, 2017 — Medical and surgical treatment
- ASCRS Clinical Practice Guidelines for the Management of Anorectal Abscess, Fistula-in-Ano and Rectovaginal Fistula, 2022 — Drainage and fistula surgery
- Sabiston Textbook of Surgery, 21st edition (2022) — Anus
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-02. The text may contain errors; when in doubt, check the source.