Collection and transport of stool specimens


Stool specimens are often required for the diagnosis and treatment of various gastrointestinal infections and disorders. These include bacterial, viral, parasitic and fungal infections, as well as inflammatory bowel diseases, malabsorption syndromes, colorectal cancer and other conditions. Stool specimens can also be used to monitor the effectiveness of therapy and to detect drug resistance.

However, stool specimens are highly susceptible to degradation and contamination by environmental factors, such as temperature, humidity, oxygen, light and microorganisms. Therefore, it is essential to collect and transport stool specimens in a proper manner to ensure their quality and reliability. Improper collection and transport of stool specimens can lead to false negative or false positive results, misdiagnosis, delayed treatment, increased morbidity and mortality, and unnecessary costs.

Some of the factors that affect the quality of stool specimens are:

  • The timing of collection: Stool specimens should be collected as soon as possible after the onset of symptoms or as instructed by the clinician. Delayed collection can result in loss of pathogens or changes in their morphology and viability.
  • The amount and type of specimen: Stool specimens should contain at least 5 g of faeces and include any parts that contain blood, mucus or pus. These parts may contain higher concentrations of pathogens or diagnostic markers. The specimen should not be contaminated with urine or water, as these can dilute or alter the specimen.
  • The container and label: Stool specimens should be placed in a suitable container with a leakproof lid and clearly labeled with the patient`s name, identification number, date and time of collection, and any relevant clinical information. The container should be clean and sterile to prevent contamination from other sources.
  • The transport medium: Stool specimens should be delivered to the clinic or laboratory within 2 hours of collection. If this is not possible, a small amount of the specimen should be transferred to a transport medium that preserves the pathogens or their antigens. Different transport media are available for different types of pathogens, such as Cary–Blair, Stuart or Amies media for bacteria; alkaline peptone water for Vibrio spp.; glycerol–phosphate buffer for viruses; and polyvinyl alcohol or formalin for parasites.
  • The storage and transport conditions: Stool specimens should be stored and transported at low temperatures (2–8°C) to prevent bacterial overgrowth, viral inactivation or parasitic degradation. They should also be protected from light and excessive heat or cold. They should be delivered to the laboratory as soon as possible after collection or within 24 hours if stored in a refrigerator.