During a routine screening camp in a school in Delhi, an ENT specialist identifies 8 children with chronic suppurative otitis media. On examination, all show perforation of the tympanic membrane. The most common site of perforation in chronic suppurative otitis media is which of the following?

Question

Accepted Answer

C. Anteroinferiror quadrant. ## Most Common Site of Tympanic Membrane Perforation in CSOM

**Key Point:** The anteroinferior (anteroventral) quadrant is the most common site of tympanic membrane perforation in chronic suppurative otitis media.

### Anatomical Basis

The tympanic membrane is divided into four quadrants by two perpendicular lines:
1. A vertical line through the umbo (manubrium mallei)
2. A horizontal line perpendicular to the vertical line

This creates:
- **Anterosuperior quadrant** (smallest area)
- **Anteroinferior quadrant** (largest area)
- **Posterosuperior quadrant** (contains the pars flaccida)
- **Posteroinferior quadrant**

### Distribution of Perforations in CSOM

| Site of Perforation | Frequency | Type of CSOM | Clinical Notes |
|---------------------|-----------|--------------|----------------|
| Anteroinferior (anteroventral) | 50–60% | Safe (tubotympanic) | Most common; safe disease |
| Posterosuperior (pars flaccida) | 20–30% | Unsafe (atticoantral) | Associated with cholesteatoma |
| Posteroinferior | 10–15% | Unsafe | Bone erosion, complications |
| Anterosuperior | <5% | Rare | Least common site |

**Clinical Pearl:** The anteroinferior quadrant is the largest area of the tympanic membrane and is most exposed to the ascending infection from the Eustachian tube. This is why it is the most frequent site of perforation in safe (tubotympanic) CSOM. In contrast, posterosuperior perforations (involving the pars flaccida) are associated with unsafe (atticoantral) disease and carry a higher risk of complications such as cholesteatoma formation.

**High-Yield:** 
- **Safe CSOM** → Anteroinferior perforation (pars tensa) → No bone erosion, low complication risk
- **Unsafe CSOM** → Posterosuperior perforation (pars flaccida) → Bone erosion, cholesteatoma, high complication risk

**Mnemonic:** **SAFE** — Safe disease = Anteroinferior perforation (pars tensa); **UNSAFE** — Unsafe disease = Posterosuperior perforation (pars flaccida).

Answer

A. Posterosuperior quadrant

Answer

B. Anterosuperior quadrant

Answer

D. Posteroinferior quadrant

During a routine screening camp in a school in Delhi, an ENT specialist identifies 8 children with chronic suppurative otitis media. On examination, all show perforation of the tympanic membrane. The most common site of perforation in chronic suppurative otitis media is which of the following?

Explanation

Most Common Site of Tympanic Membrane Perforation in CSOM

Anatomical Basis

Distribution of Perforations in CSOM

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Site of Perforation	Frequency	Type of CSOM	Clinical Notes
Anteroinferior (anteroventral)	50–60%	Safe (tubotympanic)	Most common; safe disease
Posterosuperior (pars flaccida)	20–30%	Unsafe (atticoantral)	Associated with cholesteatoma
Posteroinferior	10–15%	Unsafe	Bone erosion, complications
Anterosuperior	<5%	Rare	Least common site