Pulmonary contusion due to trauma is an example of a condition that can be asymptomatic with half of people showing no signs at the initial presentation since such symptoms can take time to develop. The CT scan shows a pulmonary contusion (red arrow) accompanied by a rib fracture (purple arrow).
In medicine, a disease is considered asymptomatic if a patient is a carrier for a disease or infection but experiences no symptoms. A condition might be asymptomatic if it fails to show the noticeable symptoms with which it is usually associated. Asymptomatic infections are also called subclinical infections. The term clinically silent is also used.
Knowing that a condition is asymptomatic is important because:
It may develop symptoms later and so require watch and wait or early treatment.
An example of an asymptomatic disease is Cytomegalovirus (CMV) which is a member of the herpes virus. "It is estimated that 1% of all newborns are infected with CMV, but the majority of infections are asymptomatic." (Knox, 1983; Kumar et al. 1984)
Asymptomatic conditions may not be discovered until the patient undergoes medical tests (X-rays or other investigations). Some people may remain asymptomatic for a remarkably long period of time; such as people with some forms of cancer. If a patient is asymptomatic, precautionary steps must be taken.
A patient's individual genetic makeup may delay or prevent the onset of symptoms.
These are conditions for which there is a sufficient number of documented individuals that are asymptomatic that it is clinically noted. For a complete list of asymptomatic infections see subclinical infection.
^Watson, A. J.; Walker, J. F.; Tomkin, G. H.; Finn, M. M.; Keogh, J. A. (1981). "Acute Wernickes encephalopathy precipitated by glucose loading". Irish journal of medical science150 (10): 301–303. doi:10.1007/BF02938260. PMID7319764. edit
^Vinson, B. (2012). Language Disorders Across the Lifespan. p. 94. Clifton Park, NY: Delmar