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General Medicine > Perianal > Flashcards

Perianal Flashcards

1
Q

Mechanisms of anal continence

A

Rectal valves (x3) = lateral curves/bends represented internally as 3 transverse folds that stop faeces from being passed with flatus

Internal anal sphincter (smooth muscle; involuntary) and external anal sphincter (skeletal muscle; voluntary) = ultimate barrier to leakage

Sympathetic NS increases sphincteric tone of internal anal sphincter (tone decreased by PSNS)

Pudendal nerve (S2-S4; somatic) innervates external anal sphincter (contracts to establish continence) → injury to nerve (e.g., in childbirth) → fecal incontinence and perianal sensory loss

Anorectal flexure formed by puborectalis muscle (of pelvic diaphragm) → forms a sling around anorectal junction forming a posterior curve that contributes to fecal continence

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2
Q

What is the pectinate/dentate line

A

Formed were endoderm (hindgut) meets ectoderm

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3
Q

What is the blood supply above pectinate line

A

Superior rectal artery (from IMA)

Superior rectal vein –> IMV –> splenic –> portal

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4
Q

What is the MC pathology above pectinate line

A

Adenocarcinoma
Internal haemorrhoids

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5
Q

What is the MC pathology below pectinate line

A

External haemorrhoids
Fissures
SCC

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6
Q

What is the blood supply below the pectinate line

A

Inferior rectal artery (branch of internal pudendal artery)

Inferior rectal vein –> internal pudendal vein –> internal iliac vein –> common iliac vein –> IVC

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7
Q

Risk factors for anal cancer

A

HPV esp. 16 and 18
Immunodeficiency e.g., HIV
MSM and receptive anal intercourse
Smoking

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8
Q

Clinical features of anal cancer

A

Rectal bleeding
Lump/mass in around anus
Pruritus ani
Anal tenderness/perianal pain
Fecal incontinence
Hx of anorectal condyloma
Anal discharge
Non-healing ulcer
Anal fistula
Inguinal node mass

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9
Q

Primary route of spread for anal cancer

A

Direct extension into soft tissues and lymphatic pathways
Haematogenous less common

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10
Q

Where do anal cancers distal to dentate line spread?

A

Superficial inguinal noes

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11
Q

Where do anal cancers proximal to or at dentate line spread?

A

Internal iliac nodes

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12
Q

Investigations for anal cancer

A
  1. Anoscopy + biopsy
  2. Pelvic MRI/CT for staging (local extension/spread into other pelvic organs/LNs)
  3. Abdominal and chest CTs to evaluate for distant mets
  4. Consider HIV tests and cervical cancer screening in females
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13
Q

Management for anal cancer

A
  1. Chemoradiation e.g., flurouracil and mitomycin
  2. Abdominoperineal resection and colostomy with locally progressive disease after chemoradiation or if disease stops responding
  3. Groin dissection if inguinal node mets
  4. Distant mets: chemo, radiotherapy, and immunotherapy
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14
Q

What is an abdominoperineal resection

A

Resection of anus, rectum and sigmoid colon with permanent colostomy

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15
Q

Why is abdominoperineal resection usually peformed

A

Rectal tumour too close to sphincter to achieve adequate distal margin without compromising sphincter, or tumour infiltrated sphincter

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16
Q

What kind of surgery is this

A

Abdominoperineal resection

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17
Q

What is an anal fissure

A

A longitudinal tear of the anal canal distal to the dentate line

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18
Q

Aetiology of anal fissures

A

Primary: due to local trauma
- chronic spasm/increased internal anal sphincter tone
- chronic diarrhoea/constipation
- anal sex
- vaginal delivery

Secondary: due to underlying disease
- IBD e.g., Crohn’s
- previous anal surgery
- granulomatous disease e.g., TB
- infections e.g., chlamydia and HIV
- malignancy

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19
Q

Where do primary anal fissures MCly occur

A

Posterior commissure at 6 o’clock in the lithiotomy position

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20
Q

Where do secondary anal fissures MCly occur

A

Lateral or anterior to posterior commissure

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21
Q

How does an anal fissure occur

A

Overdistension or disease of anal mucosa –> laceration of anoderm
- spasm of exposed internal anal sphincter pulls laceration –> impaired healing and worsening with each bowel movement
- pain –> defecation avoidance and constipation –> further distension of anal mucosa

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22
Q

Why is the posterior commissure prone to anal fissures

A

Very poor blood supply

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23
Q

Clinical features of anal fissures

A

Sharp severe pain during defecation: lasts ~ few hours after defecation and is assoc. with sphincter spasm

Rectal bleeding often bright red and minimal

Perianal pruritus

Chronic constipation (avoidance of defecation)

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24
Q

What nerve is responsible for pain in anal fissures

A

Pudendal nerve (somatic)

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25
Q

What is a chronic anal fissure

A

8-12 weeks (MC 2˚ underlying disease)

26
Q

Mx of acute anal fissure

A

Conservative
- stool softening or bulk forming laxatives
- warm salt baths after bowel movements
- OTC topical preparations containing LA can help with pain

27
Q

Mx of chronic anal fissture

A

Specialist advice

Lateral sphincterotomy/other surgery (risk of fecal incontinence)
Local botox injections

28
Q

How is anal fissure Dx

A

Clinically: laceration in anal canal

29
Q

What is a perianal abscess

A

Enclosed collection of pus within tissue that is beneath perianal skin and does not cross external sphincter

30
Q

Pathophysiology of perianal abscess

A

Obstruction of anal crypt glands in the walls of the anal canal by thick debris –> stasis and bacterial overgrowth –> abscess formation

31
Q

Aetiology of perianal asbcess

A

Obstruction and infection of anal crypt abscesses by:
- impaction of fecal matter
- oedema 2˚ to trauma from a hard stool/foreign body
- 2˚ adjacent inflammatory process e.g., Crohn’s disease

32
Q

Clinical features of perianal abscess

A

Dull perianal pain, pruritus
Swelling/erythematous mass
Low grade fever, tachycardia

Change in bowel habit (constipation)
Rectal bleeding

Hx of Crohn’s disease

33
Q

Mx of perianal abscess

A

Urgent surgical drainage
Adjunctive antibiotics

34
Q

What kinds of organisms cause infection in perianal abscess

A

Polymicrobial: aerobic and anaerobic bowel flora

35
Q

What ABx are indicated as an adjunct to surgery in perianal abscess

A

Mild: amoxicillin and clavulanic acid 875 + 125mg 12 hourly 5 days

Severe: gentamicin + metronidazole 500mg 12 hourly + 2g ampicillin/amoxicillin 2g IV 6 hourly

36
Q

What is an anal fistula

A

Abnormal connection between the epithelium surface of the anal canal and the perianal skin

37
Q

Causes of anal fistula

A

MC = complication of acute or chronic perianal abscess (extension of abscess and fistula formation)

Other:
IBD esp. Crohn’s Disease
Acute GIT infection e.g., acute appendicitis/complicated diverticulitis
Radiation induced proctitis
Foreign body
CRC/malignancy
Iatrogenic (esp. postsurgical/haemorrhoidectomy)

38
Q

Dx of perianal abscess

A

Clinical Dx
Occasionally examination under anaesthetic

39
Q

Anal fistula clinical features

A

Purulent drainage from anal canal or surrounding perianal skin
Pain during defecation
DRE: fluctuant, indurated mass, pain with pressure

40
Q

Dx of anal fistula

A

Clinical Dx
Occasionally examination under anaesthetic

41
Q

Mx anal fistula

A

Referral to CR surgeon and drainage of abscess +/- other surgery

42
Q

What might a complex or recurring anorectal abscess or fistula be a sign of

A

Crohn’s disease

43
Q

What is the most common cause of anogenital warts

A

HPV6 and 11

44
Q

What are anogenital warts called

A

Condylomata acuminata

45
Q

Clinical features of anal warts

A

Often asymptomatic –> possible pruritus, tenderness, or bleeding in rare cases

Exophytic, cauliflower-like lesions –> multiple white coalescing papules

46
Q

Complications of anal warts

A

Oncogenesis

47
Q

Dx for anal warts

A

Visual inspection
Application of acetic acid –> lesions turn white (non-specific)

Only biopsy if immunodeficiency (HIV), pt with higher risk of neoplasia, warts with atypical features, warts refractory to Tx

NB. pts should be screened for other STIs (contracted via genital to genital contact)

48
Q

Mx of anogenital warts

A

Tx not essential

Options
- Small number of lesions: cryotherapy
- Bulky/numerous lesions: topical imiquimod 5% or podophyllotoxin

49
Q

SEs of imiquimod and how to minimise these

A

Local inflammatory effects (eg burning, itch or erythema)

Reducing the frequency of application (3x week on alt days is std dose)

50
Q

What are haemorrhoids

A

Dilated submucosal vascular cushions within the anal canal that abnormally enlarge or protrude

51
Q

Aetiology haemorrhoids

A

Excessive/repetitive straining e.g., chronic constipation, diarrhoea, chronic cough, heavy lifting, BPH

Extended periods of sitting

Increased abdominal pressure: pregnancy/ascites

Pelvic mass causing decrease in vascular return and increased vascular engorgement

CT disorders e.g., EDS, scleroderma

52
Q

Differentiate bw internal and external haemorrhoids

A

Internal Haemorrhoid = above dentate line (superior hemorrhoidal plexus)

External Haemorrhoids = below dentate line (inferior hemorrhoidal plexus)

53
Q

Grade internal haemorrhoids

A

Grade I: bleed but do not prolapse

GII: prolapse when straining, but spontaneouslyreduce at rest

GIII: prolapse when straining, onlyreducible manually

GIV: irreducibleprolapse, may be strangulated and thrombosed with possible ulceration

54
Q

When are haemorrhoids painful

A

External or prolapsed internal

55
Q

Clinical features of internal haemorrhoids

A

Often painless bright red rectal bleeding at end of defecation
- above pectinate line = not innervated by cutaneous nerves

If prolapsed
- perianal mass
- may trigger anal sphincter spasm –> pain
- may become strangulated and incarcerated –> ischaemia/ necrosis/possible thrombosis –> worsening spasm and cutaneous pain
- pruritus
- anal discharge (mucus/fecal debris)
- ulceration (in haemorrhoid grade IV)

56
Q

Clinical features of external haemorrhoids

A
  • Bright red rectal bleeding at end of defecation
  • Pruritus
  • Perianal mass
  • Thrombosed external haemorrhoid: severe perianal pain and tender perianal tense blue swelling at anal margin

Innervated by pudendal nerve

57
Q

Dx of haemorrhoids

A

Clinical Dx

Anoscopy (+/- proctoscopy) usefulwhen haemorrhoids suspected but rectal examination is inconclusive

Flexible sigmoidoscopy orcolonoscopy to exclude suspectedmalignancy (esp. pts > 40yo)

FBC if concerns RE significant rectal bleeding

58
Q

Mx internal haemorrhoids

A

Lifestyle
- ensuring adequate intake of fibre and non-caffeinated fluids to avoid constipation
- avoiding straining during defecation
- responding to the urge to defecate, and not trying to initiate defecation without this.

OTC
- ointments and suppositories may contain containing emollients and a mild astringent, local anaesthetic or corticosteroid –> can help relieve itch and pain but not sustained improvement and can cause adverse effects

No response to lifestyle measures and OTC
- refer to specialist for rubber-band ligation, injection sclerotherapy or infrared coagulation
- sometimes surgery

59
Q

Natural history of thrombosed external haemorrhoids

A

Spontaneous rupture –> may resolve Sx without need for Tx
Pain settles in 1-2 weeks without Tx
Haematoma resorbs spontaneously often leaving a skin tag

60
Q

Mx thrombosed external haemorrhoids

A

Pt presenting within 72 hours of Sx onset: excision of haematoma under LA to relieve severe pain

General Medicine (3 decks)

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