Asymptomatic refers to a medical condition or disease in which a person does not display any noticeable symptoms or signs of illness. Asymptomatic disease can complicate diagnosis, and patients with asymptomatic disease may be unaware of the severity of their condition and neglect treatment.

The terms “asymptomatic” and “subclinical” are closely related, with “subclinical” referring to diseases with fewer symptoms than usual or none at all. Generally, the term asymptomatic is used interchangeably with subclinical.


  • Asymptomatic colelithiasis (gallstones): Gallstones that do not cause pain or other symptoms. They are often discovered incidentally during imaging tests such as ultrasound or CT scans.
  • Asymptomatic carriers: For example, asymptomatic carriers of the hepatitis B virus.
  • Asymptomatic bacteriuria: Bacteria in the urine without symptoms of a urinary tract infection or pyelonephritis (e.g. back pain, painful or frequent urination, blood in the urine). This condition sometimes occurs before symptomatic urinary tract infections. It is common in elderly women and patients with permanent urinary catheters. In children, it can be a sign of underlying urinary tract abnormalities. Screening for asymptomatic bacteriuria is recommended in pregnant women at 12-16 weeks of gestation. Antibiotic prophylaxis is recommended for pregnant women and those undergoing urological procedures who have asymptomatic bacteriuria. Screening of school-aged children is not necessary.
  • Asymptomatic (silent) myocardial ischemia or infarction

Importance of Asymptomatic Diseases

  1. Delayed diagnosis and treatment. Asymptomatic disease can make diagnosis more difficult
    • Examples; certain sexually transmitted infections, early-stage cancers, or latent infections like tuberculosis can be asymptomatic, leading to delayed or missed diagnoses.
  2. Patients with asymptomatic disease may not understand the severity of their condition and may neglect treatment, where individuals may not be aware of the potential long-term complications and may not adhere to treatment or lifestyle modifications.
    • Examples include asymptomatic hypertension, diabetes, cancers
  3. Transmission: Asymptomatic individuals can unknowingly spread diseases to others.
    • Examples; COVİD-19, sexually transmitted infections
  4. Public health surveillance: Identifying asymptomatic cases provides valuable information for public health surveillance.
    • Examples; influenza surveillance, tuberculosis screening
  5. Preventive measures: Knowing about asymptomatic cases can help guide preventive measures and public health interventions.
    • Examples; HIV testing, Immunization programs (vaccinations)
  6. Individual health management: Identifying asymptomatic diseases through routine screenings or health check-ups enables individuals to take necessary steps for disease management and adopt lifestyle changes to prevent or delay the onset of symptoms and complications.
    • Examples; Diabetes, hypertension, colorectal cancer or mammography screening
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