|Cell culture wash||- Requires minimal specialized equipment and is not overly tedious.|
- Can sample mucus in response to interventions [63, 64].
- Potential for repeated collection and/or longitudinal study.
|- Accumulated mucins might not be removed properly if washing is not done successively or is incomplete .|
- Samples may require pooling .
|Bronchoalveolar lavage||- Allows for direct sampling of the airway fluid|
- Applicable in vivo  and ex vivo .
- Relatively large volumes can be retrieved.
- Materials to perform are standard.
- Can be performed in human patients .
- Potential for repeated and/or longitudinal sampling.
|- Must be clinically indicated in order to perform in humans.|
- Generally done under local anesthesia in vivo .
- Fluid retrieved is a combination of multiple cells and multiple proteins .
- Volume recovered is variable .
- Non-adherent proteins may be overrepresented
|Sputum (spontaneous and induced)||- Provides information about mucus and mucins in the lower airways|
- Spontaneous sputum requires no intervention for its production
- Induced sputum provides a higher proportion of viable cells .
- Guidelines in place for inducing sputum in human .
|- Potential for contaminated with saliva.|
- Induced sputum usually requires inhalation of hypertonic saline, which can be irritating and change composition of mucus [74, 75].
- Success of sputum induction influenced by inflammation .
- Variations in the amount of sputum produced .
- Not really applicable to animal models.
|Bronchoscopy||- Direct sampling of mucus when used to remove plugs .|
- Provides significant diagnostic information.
- Can be performed in human and animal patients.
|- Performance in human patients or animal patients requires highly specialized equipment and training|
- Typically performed under conscious sedation, occasionally occur under general anesthesia .
|Endotracheal tube sampling||- Direct sampling of mucus [78, 79].||- Hydration of the mucus varies from the inside or the outside of the tube |
- Endotracheal tube placement in human and animal patients requires highly specialized training and a licensed medical practitioner.