Most stool test results come back within a few days to a week, but the real answer depends on what the lab is looking for. A test that reads genetic material can finish in hours, while one that waits for germs to grow takes days. The clock also starts only when the sample reaches the lab, which matters most for kits you mail from home.
Results Times for Infection and Parasite Tests
A stool culture means the lab tries to grow bacteria from your sample and then identifies whatever grows. That growing step is why it’s slow. A large lab chain lists 3 to 5 days for a routine result.1Labcorp. 008144: Stool Culture Information One lab found that a routine culture with nothing worrying took about 45 hours on average to report.2PubMed Central. Comparison of time-motion analysis of conventional stool culture and the BD MAX Enteric Bacterial Panel (EBP) When a possible germ turned up and needed more testing, the final result took about 4 to 6 days.3PubMed Central. Comparison of time-motion analysis of conventional stool culture and the BD MAX Enteric Bacterial Panel (EBP) Labs often send an early update, such as “no growth so far,” before the final report, which isn’t issued until the lab is confident nothing slow-growing appears.
A PCR panel checks the sample for the genetic material of many germs at once, without waiting for anything to grow. These panels return results within hours rather than days.4PubMed Central. Clinical and cost effectiveness of multiplex polymerase chain reaction gastrointestinal pathogen panels for people with suspected gastroenteritis In one hospital lab, the panel’s median time was about 2 hours, compared with about 77 hours for culture.5PubMed. Comparative evaluation of the detection rate, workflow and associated costs of a multiplex PCR panel versus conventional methods in diagnosis of infectious gastroenteritis Labs often run panels in batches, though, which can push results to about 7 hours or up to a day.6PubMed Central. Comparison of time-motion analysis of conventional stool culture and the BD MAX Enteric Bacterial Panel (EBP)7PubMed Central. Clinical and cost effectiveness of multiplex polymerase chain reaction gastrointestinal pathogen panels for people with suspected gastroenteritis
Your doctor may choose a rapid panel because it tests for many germs in one run, which helps when symptoms are severe. A culture is still used when the lab needs live bacteria to test which antibiotics work. Some clinics send a positive panel for a follow-up culture, which adds days.
A fast negative means none of the germs the rapid panel looks for were found. It doesn’t rule out every cause of diarrhea, so if symptoms continue, your doctor may order a different test.
An ova and parasites exam, where staff look for parasites and their eggs under a microscope, usually takes 3 to 7 days from pickup.8Labcorp. 008623: Ova and Parasites Examination Information Parasites shed eggs and cysts unevenly, so a single sample can miss them even when they are present. Doctors sometimes ask for samples collected on separate days, and the result is usually reported after the last one arrives, so the wait can stretch past a single sample’s timeline. If you’re given several containers, ask whether the lab waits for all of them before reporting.
Many rapid panels include a few common parasites such as Giardia and Cryptosporidium, but they don’t cover everything a microscope exam can find. A parasite exam is more often ordered after travel, a long illness, or a negative panel that didn’t explain symptoms.
C. diff is a bacterium that causes diarrhea after antibiotics. A rapid molecular test for it can finish in under an hour.9PubMed Central. Clostridium difficile testing in the clinical laboratory by use of multiple testing algorithms Older multi-step methods took about 2 extra days for positive screens.10PubMed Central. Clostridium difficile testing in the clinical laboratory by use of multiple testing algorithms
Results Times for Colon Cancer Screening Kits
A FIT kit checks stool for hidden blood and is usually mailed in or dropped off at a lab. Lab-tested results are typically ready in 1 to 5 days.11testing.com. Fecal Immunochemical Test Your doctor gets them within a few days and tells you whether you need a colonoscopy.12HonorHealth. Fecal immunochemical test (FIT) Over-the-counter FIT kits that advertise rapid results can show a result within about 5 minutes.13testing.com. Fecal Immunochemical Test
Cologuard, a stool DNA test, takes longer. Results are typically available 8 to 10 days after the kit reaches the lab.14Cologuard. Cologuard Plus® Test Return Instructions – Collect at Home, Tested in the Lab The test looks for changes in DNA as well as blood, which takes more lab work. Plan on about two weeks from collection to results, including shipping. The company says to ship the kit the same day you collect the sample, or the next day at the latest.15Cologuard. Cologuard Plus® Test Return Instructions – Collect at Home, Tested in the Lab
The biggest delay is often returning the kit. Among people who returned a FIT kit, half took 13 days or more after it was ordered.16PubMed Central. Time to Fecal Immunochemical Test Completion for Colorectal Cancer Screening People sent a Cologuard kit took about 25 days on average to return it.17PubMed Central. Member Adherence to a Health Insurer-Sponsored Gap Closure Program Using Multi-Target Stool DNA Test for Colorectal Cancer Screening Mail delays can also spoil a FIT sample, so it may have to be repeated.18PubMed Central. Potential Impact of USPS Mail Delivery Delays on Colorectal Cancer Screening Programs Collect the sample soon after the kit arrives and mail it promptly, avoiding a Friday or the day before a holiday.
Labs may reject kits that are unlabeled, mislabeled, leaking, late, or missing a collection date, because they can’t trust whose sample it is or how old it is. You will usually get a replacement kit and have to collect again, which can add two or more weeks. Before you seal the kit, check that your name and date of birth are on the tube, the collection date is filled in, and the lid is closed tight.
A positive FIT or Cologuard result does not mean you have cancer. FIT detects blood that may come from a polyp, a tumor, hemorrhoids, or other bleeding, so it can’t say which, and Cologuard can also be positive when no cancer is found. The follow-up is normally a colonoscopy, which lets the doctor look and, if needed, remove polyps during the same visit. Your doctor’s office usually calls to arrange it.
Results Times for Other Stool Tests
Calprotectin is an inflammation test used to help tell irritable bowel syndrome apart from inflammatory bowel disease. Calprotectin is a protein released by inflammation in the gut, so a high level points toward inflammatory bowel disease rather than irritable bowel syndrome. Some labs run it only on set days.19North Yorkshire CCG. Faecal Calprotectin Lower GI Pathway Information for GPs In one health service, results arrive about one week after the lab receives the sample.20North Yorkshire CCG. Faecal Calprotectin Lower GI Pathway Information for GPs Pancreatic elastase, which checks whether the pancreas makes enough digestive enzymes, takes 4 to 6 days at a large lab.21Labcorp. Pancreatic Elastase, Fecal It replaces an older 72-hour stool collection that required eating 100 grams of fat a day, so now you only need one sample.22Mayo Clinic Laboratories. Pancreatic Elastase, Feces
A raised level doesn’t say what is causing the inflammation, so it often leads to further tests such as a colonoscopy. Elastase is checked when someone has greasy, hard-to-flush stools and weight loss.
Very watery stool dilutes the enzyme being measured, which can make the pancreas look weaker than it is. A lab may ask for a more formed sample, or a doctor may read a low result cautiously. Either can lead to a repeat sample and a longer wait.
Less common tests are often grouped and run a few times a week, so the lab can process many samples with one setup of reagents and controls. A sample that arrives just after a run waits for the next one, which may be days away. That’s why two people with the same test can wait different amounts of time.
Direct-to-consumer gut health tests are the slowest, usually taking about 4 weeks for results.23Healthpath. Which Is The Best Gut Health Test Some take up to 8 weeks, especially if the sample is shipped overseas.24Healthpath. Which Is The Best Gut Health Test Microbiome reports describe which bacteria are present, which doctors rarely use for diagnosis.
Why Your Results Might Take Longer
Some stool cultures are only performed Monday through Friday.25University of Washington Department of Laboratory Medicine and Pathology. Shigella Culture, Stool A sample dropped off on Friday may not be started until Monday, so a three-day test can take about five or six calendar days. Holidays work the same way. In one hospital, most stool tests except C. diff were not run at weekends.26PubMed. Comparative evaluation of the detection rate, workflow and associated costs of a multiplex PCR panel versus conventional methods in diagnosis of infectious gastroenteritis Another hospital ran an older C. diff test only once a week, and waits reached about 6 days.27PubMed Central. Effectiveness of a Two-Step Testing Algorithm for Reliable and Cost-Effective Detection of Clostridium difficile Infection in a Tertiary Care Hospital in Saudi Arabia
Extra testing adds time too. Some germs, such as Yersinia and Vibrio, are only looked for when the doctor specifically requests them, because these bacteria need special conditions to grow.28Labcorp. 008144: Stool Culture Information Tests sent to an outside reference lab add transport time.
A short delay doesn’t usually spoil a sample that’s stored properly. Samples placed in the transport container the lab provides stay usable longer.29Drug Discoveries & Therapeutics. Effects of storage temperature, storage time, and Cary-Blair transport medium on the stability of the gut microbiota Salmonella and harmful E. coli were still detectable even when samples sat for a while.30PubMed. Viability of bacterial enteropathogens in fecal samples in the presence or absence of different types of transport media Some bacteria, like Campylobacter, were sometimes missed after delays.31PubMed. Viability of bacterial enteropathogens in fecal samples in the presence or absence of different types of transport media Follow the kit’s directions on fridge storage and return timing.
Ask the lab or doctor’s office which days your specific test is run, and when you have a choice, drop the sample off early in the week. If the sample isn’t in a preservative, get it to the lab within the window on the instructions, because waiting can make some germs harder to find.
How You’ll Get Your Results
Results go to the provider who ordered the test. US rules have pushed hospitals to release results to patients within four business days,32PubMed Central. Variation in Results Release and Patient Portal Access to Diagnostic Test Results at an Academic Medical Center so you may see a result in your portal before your doctor calls about it.
A phrase like “no enteric pathogens detected” means none of the germs tested for were found. A “preliminary” result may change once testing is finished. Ask your doctor before acting on an abnormal value.
Fast results don’t always change treatment. In one study of hospital patients with a germ identified on a rapid panel, treatment changed for 78% of them.33Open Forum Infectious Diseases. Impact of a Stool Multiplex Polymerase Chain Reaction Rapid Diagnostic Test on Antibiotic Prescribing in Patients Hospitalized With Diarrhea of Suspected Infectious Etiology Another hospital found rapid panels didn’t reduce overall antibiotic use compared with culture.34CIDRAP. Single-center study finds no reduction in antibiotic use with stool PCR tests
Wait until about two days past the expected time before calling, since weekends and batching often explain small delays. When you call, ask whether the lab received the sample and whether more testing is underway. Also ask how the office will tell you if the result is normal, since some only call about abnormal ones.
Don’t wait for results if you notice blood in your stool, a high fever, or signs of dehydration such as dizziness, very dark urine, or being unable to keep fluids down. These call for prompt medical attention regardless of what the test eventually shows.
Stool Tests for Pets
Rapid in-clinic tests for dogs take about 8 minutes.35PetMD. Fecal Tests for Dogs: What Are They, and Why Are They Important? A test that floats parasite eggs to the surface so staff can see them takes about 20 minutes.36PetMD. Fecal Tests for Dogs: What Are They, and Why Are They Important? Clinics usually call with results later that day.37PetMD. Fecal Tests for Dogs: What Are They, and Why Are They Important?
Most vet tests run on the clinic’s own equipment, so the sample never has to be shipped. It’s often processed while you’re still there, and the clinic can act right away, for example by dispensing a dewormer. Tests sent to an outside lab take days.