Stool test

Stool test
Medical diagnostics
Stool transport.JPG
Transport vials filled with human feces for stool testing. Yellow and blue tops for parasite testing, red top for stool cultures and the white top was provided by the patient with the sample.
Purposediagnose if medical condition is present

A stool test involves the collection and analysis of fecal matter to diagnose the presence or absence of a medical condition.

Visual examination

The patient and/or health care worker in the office or at the bedside is able to make some important observations.

  • Color
  • Texture/consistency—formed


One of the most common stool tests, the fecal occult blood test can be used to diagnose many conditions that cause bleeding in the gastrointestinal system including colorectal cancer or stomach cancer.[1] Cancers, and to a lesser extent, precancerous lesions, shed abnormal cells into the stool.[2] Cancers and precancerous lesions (polyps) that are ulcerated or rubbed by passing stool also may shed blood into the stool, which can be identified by a hemoglobin assay.[2]

The American Cancer Society recommends screening with either DNA testing every three years, guaiac fecal occult blood test, or fecal immunochemical test every year starting at age 50.[3] Other options include sigmoidoscopy or virtual colonoscopy (CT colonography) every five years or colonoscopy every 10 years.[4]

The U.S. Preventive Services Task Force published an updated colorectal cancer screening recommendation statement in 2016.[5]

The National Comprehensive Cancer Network (NCCN) published screening guidelines in 2016.[6]

In 2016 the National Committee for Quality Assurance (NCQA) issued an update to the Healthcare Effectiveness Data and Information Set (HEDIS) for 2017.[7]

A DNA test using stool samples was approved in August 2014 by the FDA as a screening test for non-symptomatic, average-risk adults 50 years or older.[8] A 2017 study found this testing to be less cost effective as compared to colonoscopy or fecal occult blood testing.[9] Three-year sDNA screening has been estimated to cost $11,313 per quality adjusted life year (QALY) compared with no screening.[10]

Microbiology tests

Parasitic diseases such as ascariasis, hookworm, strongyloidiasis and whipworm can be diagnosed by examining stools under a microscope for the presence of worm larvae or eggs. Some bacterial diseases can be detected with a stool culture. Toxins from bacteria such as Clostridium difficile ("C. diff.") can also be identified. Viruses such as rotavirus can also be found in stools.[11]

Chemical tests

A fecal pH test may be used to determine lactose intolerance or the presence of an infection.[12] Steatorrhea can be diagnosed using a Fecal fat test that checks for the malabsorption of fat.[13]

Faecal elastase levels are becoming the mainstay of pancreatitis diagnosis.

See also


  1. ^ "Fecal Occult Blood Test (FOBT)".
  2. ^ a b Osborn, NK; Ahlquist, DA (2005). "Stool screening for colorectal cancer: molecular approaches". Gastroenterology. 128 (1): 192–206. doi:10.1053/j.gastro.2004.10.041. PMID 15633136.
  3. ^ Smith, RA; Manassaram-Baptiste, D; Brooks, D; et al. (2015). "Cancer screening in the United States, 2015: a review of current American Cancer Society guidelines and current issues in cancer screening". CA Cancer J Clin. 65 (1): 30–54. doi:10.3322/caac.21261.
  4. ^ "American Cancer Society recommendations for colorectal cancer early detection". www.cancer.org. Retrieved 14 July 2016.
  5. ^ Bibbins-Domingo, Kirsten; Grossman, David C.; Curry, Susan J.; Davidson, Karina W.; Epling, John W.; García, Francisco A. R.; Gillman, Matthew W.; Harper, Diane M.; Kemper, Alex R.; Krist, Alex H.; Kurth, Ann E.; Landefeld, C. Seth; Mangione, Carol M.; Owens, Douglas K.; Phillips, William R.; Phipps, Maureen G.; Pignone, Michael P.; Siu, Albert L. (2016). "Screening for Colorectal Cancer". JAMA. 315 (23): 2564–2575. doi:10.1001/jama.2016.5989. ISSN 0098-7484. PMID 27304597.
  6. ^ National Comprehensive Cancer Network. "National Comprehensive Cancer Network". NCCN GUIDELINES FOR DETECTION, PREVENTION, & RISK REDUCTION. Retrieved October 31, 2016.
  7. ^ National Committee for Quality Assurance. "Healthcare Effectiveness Data and Information Set 2017 Volume 2: Technical Update" (PDF).
  8. ^ "FDA approves first non-invasive DNA screening test for colorectal cancer [press release]". Food and Drug Administration. August 11, 2014. Retrieved 30 June 2015.
  9. ^ Barzi, A; Lenz, HJ; Quinn, DI; Sadeghi, S (1 May 2017). "Comparative effectiveness of screening strategies for colorectal cancer". Cancer. 123 (9): 1516–1527. doi:10.1002/cncr.30518. PMID 28117881.
  10. ^ Berger, BM; Shroy, PC; Dinh, TA (2015). "Screening for Colorectal Cancer Using a Multitarget Stool DNA Test: Modeling the Effect of the Intertest Interval on Clinical Effectiveness". Clinical Colorectal Cancer. Epub ahead of print (3): e65–e74. doi:10.1016/j.clcc.2015.12.003. PMID 26792032.
  11. ^ "Stool culture".
  12. ^ "Stool Acidity Test - MedicineNet.com".
  13. ^ "MedlinePlus Medical Encyclopedia: Fecal fat".

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