Neobook — clinical reference

Introduction
Differential Diagnosis
Clinical Clues to the Common Diagnoses
Evaluation Priorities

Context: Casualty or OPD

Introduction

Perianal pain is a common reason to a visit to the emergency department. Most causes of such pain are unpleasant for the patient, but seldom life-threatening.

There is no substitute for a sound approach and thorough evaluation of such cases. Almost all cases can be confidently diagnosed on clinical grounds alone, and do not require extensive investigations. So, as always, apply your mind and MAKE A CLINICAL DIAGNOSIS!

Patients will almost always refer to any perianal symptom as caused by "piles" or "haemorrhoids." In reality, haemorrhoids are an uncommon cause of perianal pain, and another diagnosis is usually responsible for the patient's symptoms.

Similarly, casualty officers referring patients to the surgeon on call seldom examine the perineum and anal region thoroughly and will label the patients with a cursory "surgical" diagnosis to get you (the surgeon) to sort it out. So don't rely on referral diagnosis either, it is often incorrect.

Try to decide if this is a brand new symptom, or if it reflects a progression of long-standing disease. Importantly, try to decide just how bad the pain is.

Differential Diagnosis

Causes of severe "excruciating" perianal pain

Common

Perianal or ischiorectal abscess
Fissure in a

Rare

Acutely prolapsed thrombosed haemorrhoids
Herpes simplex
Anal trauma
Severe proctitis
Entero-vaginal fistula

Don't want to miss

Nectrotizing fasciitis (Fournier's gangrene)

Causes of moderate perianal "discomfort"

Common

Perianal fistula
Thrombosed varix or "perianal haematoma"
Condylomata acuminata
Proctalgia fugax

Rare

Prostate abscess
Crohn's disease of perineum
Severe hidradenitis suppurativa
Anal prolapse

Don't want to miss

Anal carcinoma or low rectal cancer invading the sphincters

Flags for uncommon diagnoses: the clinical context & co-morbidity may alert you to some less common pathology - just think about them!

Uncommon diagnoses
Diabetic	Perianal & ischiorectal abscess or necrotising fasciitis
HIV+	TB abscess, lymphoma, rectal Kaposi, condylomata acuminata, "vanishing perineum syndrome"
Anaemia & Cachexia	Anal cancer, Crohn's disease, TB
MSM	Anal trauma, herpes, condylomata
Elderly	Rectal prolapse
Infant, child	Constipation and fissure in ano, consider sexual abuse in unusual cases
Pregnant or postpartum	Grade IV haemorrhoids
Recent pelvic radiotherapy	Radiation proctitis
Inflammatory bowel disease	Perineal Crohn's fistulae with "watering can" perineum

The diagnosis always rests on a thorough evaluation of the patient and a comprehensive examination of the perineum. This should be performed in a private space, with adequate illumination, and instrumentation to examine the anal canal and rectum.

Many patients with severe pain are unable to tolerate even a digital examination, they should undergo a "EUA" - examination under anaesthesia, as an urgent step, or be comprehensively examined once the pain subsides.

Clinical Clues to the Common Diagnoses

Diagnosis	History	Clinical Findings
Fissure in ano	The hallmark symptom is severe pain on passing stool Pain often lasts for hours following defecation Fissures can also be associated with limited anal bleeding/spotting	Longitudinal tear in the anoderm that usually extends no more proximally than the dentate line acute fissure = fresh, superficial laceration Chronic fissure = raised edges exposing the white, sphincter muscle fibres; often accompanied by external skin tags (sentinel pile). The patient does not tolerate a PR exam
Perianal or ischiorectal abscess	Severe constant pain in the anal or rectal area; not necessarily associated with a bowel movement. Fever is common. Purulent rectal drainage may be noted if the abscess has begun to drain spontaneously	Fluctuance and/or erythematous, indurated skin. Patients with a deeper (eg, supra levator) abscess, may not have any physical findings on external examination, and the abscess can only be felt via digital rectal examination under EUA
Perianal fistula	Perianal discomfort, and intermittent drainage of pus/ fluid into the underwear. Severe pain may be present if associated with an acute abscess. The previous history of a perianal abscess is common	Draining sinus anywhere in the circumference of the anal margin. The drainage from the fistula tract can be purulent
"Perianal haematoma"	Sudden onset pain, rapidly increasing in severity up to a persistent throbbing pain at 48 to 72 hours. This is not a haemorrhoid and can be treated with local drainage of the blood clot	Obviously, tender lump is present at the anal margin. It is covered by stratified squamous epithelium, is bluish and has a soft rubber consistency
Proctalgia fugax	Attacks of severe anorectal pain that may last from a few seconds to minutes, with an average duration of five minutes. Patients are asymptomatic between episodes	Normal examination
Condylomata acuminata	The sensation of perianal mass and discomfort. If in severe pain, consider another cause!	Multiple soft, smooth or papillated papules or plaques limited to the anogenital area
Acutely prolapsed and thrombosed haemorrhoids	Presents with severe pain. Oedematous shiny “bunch of grapes” protruding from the anus	This will settle with good analgesia over a period of +/-10 days. There is no role for incision and drainage and surgery is almost never needed

Evaluation Priorities

The only diagnosis that needs URGENT intervention is drainage of an abscess or debridement in a case of suspected necrotizing fasciitis.

If your working diagnosis is one of these two conditions, a patient needs admission to hospital and an urgent EUA & treatment plan.

All other conditions are treated on their merits, usually conservatively at first; the details depend on the diagnosis.

Expensive perianal imaging (like an MRI) is at the discretion of colorectal consultants only, and is best done AFTER a proper EUA is performed.