View source for Sputum

{{short description|Mucus that is coughed up from the lower airways}}
{{More medical citations needed|date=September 2023}}
{{Infobox medical condition (new)
| name            = Abnormal sputum
| synonyms        = Mucus
| image           = Enterococcus histological pneumonia 01.png
| caption         = [[Cocci]]-shaped ''[[Enterococcus]]'' sp. [[bacteria]] taken from a [[pneumonia]] patient
| pronounce       = {{IPA|/'spju:təm/}}
| field           = [[Pulmonology]]
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'''Sputum''' is [[mucus]] that is coughed up from the lower airways (the [[trachea]] and [[bronchi]]). In medicine, sputum samples are usually used for a naked-eye examination, microbiological investigation of respiratory infections, and [[Cytopathology|cytological]] investigations of respiratory system.

A naked eye exam of the sputum can be done at home by a patient in order to note the various colors (see below). Any hint of yellow or green color ([[pus]]) suggests an airway infection (but does not indicate the type of organism causing it). Such color hints are best detected when the sputum is viewed against a bright white background, such as white paper, a white pot, or a white sink surface. 

Having green, yellow, or thickened phlegm (sputum) does not always indicate the presence of an infection. Also, if an infection is present, the color of the phlegm (sputum) does not determine whether a virus, a bacterium or another pathogen has caused it. Simple allergies can also cause changes in the color of mucus.<ref>{{Cite web|title=Green phlegm and snot 'not always a sign of an infection needing antibiotics'|url=https://www.gov.uk/government/news/green-phlegm-and-snot-not-always-a-sign-of-an-infection-needing-antibiotics|access-date=2022-04-17|website=GOV.UK|date=18 November 2013 |language=en}}</ref>

==Description==
The best sputum samples contain very little [[saliva]],<ref>[https://www.ncbi.nlm.nih.gov/nlmcatalog/101315566 Clinical Microbiology procedures handbook], American Society for Microbiology 2nd Ed. 2007 update</ref> as saliva contaminates the sample with oral [[bacteria]]. This is especially true for samples for laboratory testing in [[cytology]] or [[microbiology]]. Specimen adequacy is assessed by the laboratory technologists by examining a [[Gram stain]] or cytology stain of the sputum. More than 25 [[Squamous epithelium|squamous epithelial]] cells at low power magnification exam under the microscope strongly suggest salivary contamination.<ref>{{cite journal|last1=Gershman|first1=Neil H.|last2=Liu|first2=Hong|last3=Wong|first3=Hofer H.|last4=Liu|first4=Jane T.|last5=Fahy|first5=John V.|title=Fractional analysis of sequential induced sputum samples during sputum induction: Evidence that different lung compartments are sampled at different time points|journal=Journal of Allergy and Clinical Immunology|date=August 1999|volume=104|issue=2|pages=322–328|doi=10.1016/S0091-6749(99)70374-X|pmid=10452752|doi-access=free}}</ref> Sputum samples have been used to quantify the degree of airway inflammation in human diseases such as asthma. Specifically, this work has demonstrated that a subgroup of severe asthma patients has airway inflammation that is resistant to treatment with corticosteroids.<ref>{{cite journal|last1=Peters|first1=Michael C.|last2=Kerr|first2=Sheena|last3=Dunican|first3=Eleanor M.|last4=Woodruff|first4=Prescott G.|last5=Fajt|first5=Merritt L.|last6=Levy|first6=Bruce D.|last7=Israel|first7=Elliot|last8=Phillips|first8=Brenda R.|last9=Mauger|first9=David T.|last10=Comhair|first10=Suzy A.|last11=Erzurum|first11=Serpil C.|last12=Johansson|first12=Mats W.|last13=Jarjour|first13=Nizar N.|last14=Coverstone|first14=Andrea M.|last15=Castro|first15=Mario|last16=Hastie|first16=Annette T.|last17=Bleecker|first17=Eugene R.|last18=Wenzel|first18=Sally E.|last19=Fahy|first19=John V.|title=Refractory airway type 2 inflammation in a large subgroup of asthmatic patients treated with inhaled corticosteroids|journal=Journal of Allergy and Clinical Immunology|volume=143|issue=1|pages=104–113.e14|date=March 2018|doi=10.1016/j.jaci.2017.12.1009|pmid=29524537|pmc=6128784}}</ref>

When a sputum specimen is plated out in microbiology, it is best to get the portion of the sample that almost looks like yellow pus onto the swab. If there is any blood in the sputum, this should also be on the swab.{{citation needed|date=July 2007}} Microbiological sputum samples are used to look for infections, such as ''[[Moraxella catarrhalis]]'', ''[[Mycobacterium tuberculosis]]'', ''[[Streptococcus pneumoniae]]'', and ''[[Haemophilus influenzae]]''. Other [[pathogens]] can also be found.

[[wikt:purulent|Purulent]] sputum<ref name="DeGowin's">{{cite book|author=Richard F. LeBlond|author2=Richard L. DeGowin|author3=Donald E. Brown|title=DeGowin's diagnostic examination|location=New York|publisher=McGraw-Hill|date=2004|isbn=0-07-140923-8}}</ref> contains [[pus]], composed of [[Leukocyte|white blood cells]], cellular debris, dead tissue, [[serous fluid]], and viscous liquid ([[mucus]]). Purulent sputum is typically yellow or green. It is seen in cases of pneumonia, [[bronchiectasis]], [[lung abscess]], or an advanced stage of [[bronchitis]].<ref>[https://www.medicalnewstoday.com/articles/318924 What can sputum tell us?]</ref>

==Interpretation==
Sputum can be (when examined by the naked eye):{{Citation needed|date=April 2018}}
*Bloody<ref name="DeGowin's"/> ([[hemoptysis]])
**Blood-streaked sputum –an indicator of possible inflammation of the throat (larynx and/or trachea) or bronchi; [[lung cancer]]; other bleeding erosions, ulcers, or tumors of the lower airway.
**Pink sputum – it indicates sputum evenly mixed with blood from [[Pulmonary alveolus|alveoli]] and/or small peripheral bronchi as is seen in potential [[pulmonary edema]].
**Massive blood – an indicator of possible cavitary [[tuberculosis]] or tumor such as [[lung cancer]], or [[lung abscess]]; [[bronchiectasis]]; lung [[infarction]]; pulmonary [[embolism]].
**Red, jelly-like sputum - an indicator of possible pneumonia caused by [[Klebsiella]].
*Green or greenish colored - indicative of potential longstanding respiratory infection (green from degenerative changes in cell debris) as in pneumonia, ruptured lung abscess, chronic infectious bronchitis, and infected bronchiectasis or cystic fibrosis.
*Rust colored – usually caused by [[pneumococcal]] bacteria (in [[pneumonia]]), pulmonary [[embolism]], [[lung cancer]] or pulmonary [[tuberculosis]]. 
*Brownish –potential indicator of chronic bronchitis (greenish/yellowish/brown); chronic pneumonia (whitish-brown); [[tuberculosis]]; [[lung cancer]]. 
*Yellow, yellowish [[purulent]] – an indicator of the sample containing pus. "The sputum color of patients with acute cough and no underlying chronic lung disease does not imply therapeutic consequences such as prescription of antibiotics."<ref>{{cite journal|pmc = 3410464|pmid=19242860|doi=10.1080/02813430902759663|volume=27|issue=2|title=Sputum color for diagnosis of a bacterial infection in patients with acute cough|vauthors=Altiner A, Wilm S, Däubener W, Bormann C, Pentzek M, Abholz HH, Scherer M|authorlink7=Martin Scherer|journal=Scand J Prim Health Care|pages=70–3|year=2009}}</ref> The color can provide hints as to effective treatment in chronic bronchitis patients:<ref>[https://web.archive.org/web/20110203101936/http://www.pulmonaryreviews.com:80/aug00/pr_aug00_sputum.html Sputum Color is the Key to Treating Acute COPD Exacerbations]</ref>
**A yellow-greenish (mucopurulent) color suggests that treatment with antibiotics can reduce symptoms. The green color is caused by degenerating neutrophil [[Myeloperoxidase|verdoperoxidase]].
*Whitish gray sputum color against a white color background (such as a white sink surface) tends to indicate either a specimen from someone who is dehydrated, and/or from an older person, and/or a specimen with a mixed, modest number of eosinophils and maybe some acute inflammatory neutrophil cells (this last choice tends to suggest chronic allergic bronchitis).
*A white, milky, or opaque (mucoid) appearance means that antibiotics are less likely to be effective in treatment because the likelihood is greater of a viral infection or allergy than of antibiotic-responsive micro-organisms. Thickness may indicate asthma.
*Foamy white – may come from earlier-phase [[pulmonary edema]].
*Frothy pink – may indicate more severe [[pulmonary edema]]. Antibiotics may not be necessary at this time. 
*Clear – pulmonary [[embolism]] (clear to frothy); COPD [[chronic obstructive pulmonary disease]] (clear to gray); viral respiratory infection (clear to whitish and sometimes a hint of yellow); [[asthma]] (thick and white to yellowish).

==See also==
*[[Phlegm]]

==References==
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==External links==
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{{Circulatory and respiratory system symptoms and signs}}

[[Category:Symptoms and signs: Respiratory system]]