What is fetor?

Fetor: Definition and Clinical Significance

Fetor refers to an unpleasant or foul odor emanating from the body, most commonly from the mouth (fetor oris or fetor ex ore), but can also originate from other sources depending on underlying pathology.

Types and Causes of Fetor

Oral Fetor (Fetor Oris/Fetor Ex Ore)

• Primary causes:

  • Poor oral hygiene with plaque and calculus accumulation 1
  • Bacterial decomposition on the tongue dorsum (most important retention site) 2
  • Periodontal disease (patients with fetor ex ore have more severe periodontal disease) 1
  • Anaerobic bacterial overgrowth, particularly gram-negative bacteria 2

• Contributing factors:

  • Infrequent dental visits (visits once every 3 years significantly correlated with fetor) 1
  • Nighttime and between meals (optimal conditions for odor production) 2

Disease-Specific Fetor

1. Fetor Hepaticus

   • Sweet, musty, or slightly fecal aroma in patients with hepatocellular failure
   • Caused by volatile sulfur compounds and nitrogenous substances 3
   • Excessive trimethylamine contributes to the "fish-like" odor in 50% of liver disease patients 3

2. Atrophic Rhinitis Fetor

   • Characteristic of primary (idiopathic) atrophic rhinitis
   • Associated with nasal crusting, dryness, and progressive atrophy of nasal mucosa 4
   • Potential bacterial causes include Klebsiella ozaenae, S. aureus, Proteus mirabilis, and E. coli 4

3. Tumor-Associated Fetor

   • Common in extensive head and neck tumors
   • Caused by anaerobic bacterial superinfection, especially Bacteroides melaninogenicus 5
   • Extremely unpleasant for patients, family members, and healthcare staff 5

4. Genital Fetor

   • Can result from sweat secretion and bacterial decomposition of sweat components 6
   • May be localized to hair-bearing areas in the genital region 6

5. Systemic Disease-Related Fetor

   • Diabetes mellitus, uremia, and hepatic diseases can produce metabolic products detectable as oral odors 2

Diagnostic Approach

• Clinical detection by healthcare providers during examination
• Patients with true fetor are often unaware of their condition (contrasts with halitophobia, where patients perceive bad breath that others cannot detect) 1
• Comprehensive oral examination to identify:
  • Dental plaque and calculus
  • Periodontal pockets
  • Tongue coating
  • Signs of systemic disease

Treatment Strategies

1. For Oral Fetor:

   • Improved oral hygiene practices
   • Regular dental visits
   • Treatment of underlying periodontal disease 1
   • Tongue cleaning to reduce bacterial load on dorsum 2

2. For Tumor-Associated Fetor:

   • Antibiotic therapy targeting anaerobes
   • Clindamycin has proven superior to metronidazole
   • Fetor typically disappears within 12-36 hours of antibiotic initiation 5

3. For Atrophic Rhinitis Fetor:

   • Continuous nasal hygiene (nasal lavage with saline or sodium bicarbonate)
   • Periodic debridement of crusts
   • Topical or systemic antibiotics for purulent secretions or acute infection 4

4. For Genital Fetor:

   • In cases related to sweat gland activity, botulinum toxin A injections have shown effectiveness 6
   • Improved hygiene practices

5. For Systemic Disease-Related Fetor:

   • Treatment of the underlying condition (diabetes, liver disease, kidney disease)
   • In liver disease patients with trimethylamine-related fetor, addressing the hepatic dysfunction 3

Clinical Pearls and Pitfalls

• Important distinction: True fetor (objectively detected by others) versus halitophobia (subjectively perceived but not detected by others) 1
• Fetor is often a sign of underlying pathology and should prompt investigation rather than just symptomatic treatment
• In patients with head and neck tumors, persistent fetor despite antibiotic treatment may indicate inadequate coverage or resistant organisms 5
• The dorsum of the tongue is often overlooked but is a critical site for bacterial retention and fetor production 2
• Patients with fetor are frequently unaware of their condition, making it important for healthcare providers to address the issue sensitively

Special Considerations

• Fetor in atrophic rhinitis presents with paradoxical symptoms - patients perceive severe nasal congestion despite abnormally wide nasal cavities on examination 4
• In patients with liver disease, the degree of trimethylamine excretion correlates with disease severity, with 17% of patients having levels above the threshold for detectable "fish-like" odor 3
• Regular dental visits (more frequent than every 3 years) significantly reduce the risk of developing fetor ex ore 1