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ASOM, CSOM & Otoscope - Complete Guide

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🔬 THE OTOSCOPE - Parts & How It Works

Otoscope with Ear Anatomy

Parts of the Otoscope

• Standard (hand-held) otoscope - for routine examination; monocular, limited magnification
• Pneumatic otoscope - has the bulb attachment for assessing TM mobility (very useful to detect middle ear fluid)
• Operating otoscope - lens swings aside so you can insert instruments to remove cerumen or foreign bodies
• Binocular microscope (otomicroscope) - provides stereoscopic (3D) vision, higher magnification, two-handed technique

The Tympanic Membrane (what you see through the otoscope)

1. Handle of malleus - the first thing to identify; a white diagonal stripe
2. Lateral process of malleus - small bony bump at the top of the handle
3. Umbo - the bottom tip of the malleus handle; the most concave point of the TM
4. Cone of light (light reflex) - a triangular reflection from the umbo pointing anteriorly-inferiorly
5. Pars tensa - the main, taut part of the TM (lower 4 quadrants)
6. Pars flaccida - the small, floppy upper part above the mallear folds
7. Anterior mallear fold and Posterior mallear fold - folds bordering the pars flaccida

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⚡ ASOM - Acute Suppurative Otitis Media

What is it?

Common Causes (Pathogens)

How Does It Start? (Pathogenesis)

1. Upper respiratory tract infection (common cold) inflames and swells the Eustachian tube
2. Eustachian tube dysfunction - tube that connects the middle ear to the back of the nose gets blocked
3. Bacteria travel up from the nasopharynx into the middle ear
4. Pus builds up in the middle ear cavity, increasing pressure

Stages of ASOM (Classic teaching)

Symptoms

• Ear pain (otalgia) - main symptom, sudden onset
• Fever, general unwellness
• Hearing loss (conductive)
• Children may pull at their ears, be irritable, have poor appetite
• Otorrhoea (ear discharge) if TM perforates - pain dramatically improves at this point

What You See on Otoscopy

• TM is red and opaque (erythematous)
• Bulging outward - this is the most important sign (moderate-severe bulging highly predictive of AOM)
• No light reflex or distorted
• Landmarks obscured by swelling
• TM immobile on pneumatic otoscopy
• If perforated: visible hole, pus draining

Treatment

• Antibiotics: Amoxicillin is first-line; amoxicillin-clavulanate if treatment failure or severe
• Analgesia: Paracetamol/ibuprofen for pain
• Watchful waiting acceptable in mild/moderate cases in children >2 years
• Myringotomy (surgical TM incision to drain pus) if severe or not improving

Complications of ASOM

• Mastoiditis (most common complication)
• Facial nerve paralysis
• Meningitis, intracranial abscess
• Sensorineural hearing loss
• Progression to CSOM if not treated

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🔄 CSOM - Chronic Suppurative Otitis Media

What is it?

WHO estimates 65-330 million people worldwide have CSOM; 50% suffer from hearing impairment. (Scott-Brown's Otorhinolaryngology)

How is CSOM Different from ASOM?

Types of CSOM

Type 1 - Tubotympanic (Safe / Mucosal) CSOM

• Perforation in the pars tensa (central/anterior)
• Mucoid or mucopurulent discharge
• No cholesteatoma
• Hearing loss present but generally less severe
• Generally considered "safe" (fewer dangerous complications)

Type 2 - Atticoantral (Unsafe / Squamous) CSOM

• Perforation in the pars flaccida or posterior-superior pars tensa (marginal/attic)
• Cholesteatoma present (accumulation of keratin-producing squamous epithelium)
• Foul-smelling, scanty discharge
• More aggressive bone destruction
• Called "unsafe" due to serious complication risk

Otoscopic Findings in CSOM

• Visible perforation in the TM (central or marginal depending on type)
• Pus/discharge in the canal or through the perforation
• Granulation tissue around the perforation edges
• In cholesteatoma: pearly white mass visible, usually in the attic region
• Marginal perforations suggest unsafe/cholesteatoma type

Symptoms

• Otorrhoea (ear discharge) - intermittent or continuous; may be mucoid or foul-smelling
• Hearing loss (conductive) - degree depends on extent of damage
• No or minimal pain (distinguishes from ASOM)
• Tinnitus

Complications of CSOM

• Mastoiditis
• Facial nerve palsy
• Labyrinthitis

• Meningitis
• Brain abscess
• Lateral sinus thrombosis

Treatment

• Medical: Aural toileting (cleaning the ear), topical antibiotic drops (ciprofloxacin), treat underlying infections
• Surgical:
  • Myringoplasty - repair of the TM perforation (when ear is dry)
  • Tympanoplasty - reconstruction of TM and ossicles
  • Mastoidectomy - removal of diseased mastoid bone (especially if cholesteatoma)
  • For cochlear implant candidates: staged approach - clear disease first, implant after ear is dry

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🔑 Quick Comparison Table: ASOM vs CSOM

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📋 Structured Otoscopy Approach (How to Examine)

1. Choose the largest speculum that fits comfortably
2. Pull the pinna up and backward (adults) to straighten the canal
3. Identify the malleus handle first - your anchor point
4. Find the lateral process (small bump, top of handle)
5. Find the umbo (bottom tip of handle)
6. Look for the cone of light (antero-inferior)
7. Assess pars tensa - is it intact? Normal position? Retracted? Bulging?
8. Assess pars flaccida (attic) - for retraction pockets or cholesteatoma
9. Use the pneumatic bulb - squeeze gently and watch for TM movement (no movement = fluid or perforation)

"The most recognizable feature in most ears is the handle of malleus and this should be the first structure sought." - Scott-Brown's Otorhinolaryngology

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Refractive Errors - Complete Visual Guide 👁️

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What is a Refractive Error?

"In emmetropia, parallel rays from infinity are focused perfectly on the retina. In myopia, the globe is too long and light rays come to a focal point in front of the retina. In hyperopia, the globe is too short..." - Harrison's Principles of Internal Medicine 22E

The Big Picture - All 4 Refractive Errors

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The 4 Types of Refractive Error

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1. 👀 MYOPIA (Nearsightedness / Short-sightedness)

What happens?

• The eyeball is too long (axial length), OR the cornea is too steeply curved
• Light focuses in FRONT of the retina instead of on it
• You can see near objects clearly, but distant objects are blurry

Vision Correction Diagram

Key Facts

Simple analogy

Danger - Pathologic Myopia

• Retinal detachment
• Retinal holes
• Choroidal neovascularization
• Associated with Marfan syndrome, Stickler syndrome

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2. 🔭 HYPEROPIA (Farsightedness / Long-sightedness)

What happens?

• The eyeball is too short, OR the cornea is too flat
• Light focuses BEHIND the retina
• Near objects are blurry; in young people the lens can compensate partially by "accommodating" (squeezing itself to bend light more)

Key Facts

Simple analogy

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3. 🏉 ASTIGMATISM

What happens?

• The cornea (or lens) is oval/football-shaped instead of perfectly round
• Different parts of the cornea have different curvatures (like a rugby ball vs. a basketball)
• Light focuses at multiple points instead of one single point
• Vision is blurry AND distorted at ALL distances

Astigmatism vs Normal Eye

Types of Astigmatism

Key Facts

What does astigmatic vision look like?

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4. 📖 PRESBYOPIA (Age-related near vision loss)

What happens?

Normal Accommodation (Young Eye)

How accommodation works (and why presbyopia happens):

YOUNG EYE looking at something near:
Ciliary muscle CONTRACTS → Zonule fibres RELAX → Lens becomes FAT & round → More power → Near focus ✓

PRESBYOPIC EYE (age 40+):
Lens becomes STIFF & hard → Even when ciliary muscle contracts, lens CANNOT change shape → Near focus FAILS ✗

Key Facts

Progression with age

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Snellen Chart - Testing Visual Acuity

• 20/20 = Normal vision
• 20/40 = Minimum for driving (most states/countries)
• 20/200 = Legal blindness threshold
• Pinhole test: Placing a pinhole in front of the eye sharpens blurred vision caused by refractive error - if pinhole improves vision, refractive error is the cause

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Treatment Summary

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Quick Memory Aid

Myopia = Minus lens (concave) - can't see Mountains far away Hyperopia = plus lens (convex) - can't read the Headline close up Astigmatism = All distances blurry - football-shaped cornea Presbyopia = over 40 - Phone goes further away to read

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ANASTOMOSIS - Complete Guide 🔗

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What is an Anastomosis?

"An anastomosis is a surgical connection between two tubes in your body. This could be between two blood vessels or between two parts of your intestines." - Cleveland Clinic

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Where are Anastomoses Used?

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The 3 Basic Types (Configurations)

1. 🔴 End-to-End Anastomosis (EEA)

• The two open ends of two structures are joined directly together
• Like screwing two pipes end-to-end
• Best used when: Both segments are roughly the same diameter
• Common examples: Rectal resections, small bowel joins, colocolic anastomosis

2. 🔵 End-to-Side Anastomosis

• The open end of one structure is sewn into the side of another structure
• Like connecting a small pipe into the side of a larger main pipe
• Best used when: One piece of bowel is larger than the other (e.g. after chronic obstruction)
• Common examples: Ileocolic anastomosis, esophagogastric joins, liver transplant portal vein

3. 🟢 Side-to-Side Anastomosis

• The sides of two structures are sewn/stapled together, creating a wide connection
• Like joining two parallel pipes together along their lengths
• Best used when: You want a large, well-vascularized join on the antimesenteric side
• Common examples: Small bowel anastomoses, ileocolic joins (most common technique with staplers)

"The geometry of the anastomosis may be end-to-end, end-to-side, side-to-end, or side-to-side. The submucosal layer of the intestine provides the strength of the bowel wall and must be incorporated in the anastomosis to assure healing." - Schwartz's Principles of Surgery 11th Ed.

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The 2 Techniques: How Surgeons Make an Anastomosis

🧵 Hand-Sewn (Sutured) Technique

• Surgeon uses sutures (stitches) to sew the two ends together
• Can be done with single layer or double layer of sutures
• Sutures can be interrupted (individual knots) or continuous (running stitch)
• The submucosal layer must always be included - it provides the strength
• Can be done in any configuration (end-to-end, end-to-side, side-to-side)

🔧 Stapled Technique

• Uses mechanical stapling devices to join the structures
• Linear stapler: Cuts and staples simultaneously; used for side-to-side joins
• Circular/EEA stapler: Creates a round anastomosis; used especially for low rectal or esophageal joins where hand-sewing is physically difficult
• Double-stapling technique: Particularly used in the pelvis - rectal stump is closed with one stapler, then circular stapler is passed up through the anus to create the anastomosis

"No anastomotic technique has been proven to be superior... Accurate approximation of two well-vascularized, healthy limbs of bowel without tension almost always results in a good outcome." - Schwartz's Principles of Surgery

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The Golden Rules for a Safe Anastomosis

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How an Anastomosis Heals

1. Inflammatory phase (Days 0-3): Old collagen is broken down by collagenase - the anastomosis is at its WEAKEST. This is the danger window for leaks.
2. Proliferative phase (Days 4-14): Fibroblasts make new collagen; strength rapidly increases
3. Remodelling phase (Weeks to months): Collagen matures and cross-links; the join becomes strong

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The Most Feared Complication: Anastomotic Leak

What is it?

"Anastomotic dehiscence is one of the most dreaded complications in colorectal surgery with rates ranging from 3% to 21%." - Sleisenger and Fordtran's GI and Liver Disease

Risk Factors for Anastomotic Leak

Signs of Anastomotic Leak (post-op)

• Fever on day 3-5 (classic!)
• Tachycardia
• Abdominal pain/peritonitis
• Purulent or faeculent drainage
• CT scan confirms: free fluid, gas, or extravasation of contrast

Prevention Strategies

• Diverting ileostomy (loop ileostomy): A temporary stoma is created upstream to divert faeces away from the anastomosis while it heals - if leak occurs, consequences are less severe
• Ghost/Virtual ileostomy: A vessel loop is placed around a bowel loop and brought to skin - if a leak occurs, it can quickly be converted to a real stoma at bedside
• Intraoperative leak test: Air insufflation into the rectum while the pelvis is filled with saline - bubbles = defect in the anastomosis

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Special Types of Anastomoses (Named Procedures)

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Quick Summary Table

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