How to collect a stool sample: a practical step-by-step guide

A stool sample lets the laboratory examine what is in your digestive system. The East Kent Hospitals leaflet explains that stools contain bacteria and other substances found in the digestive system, and that checking them helps the doctor work out whether there are problems. Depending on what your clinician is looking for, a stool sample can be used to test for infection-causing bacteria, parasites or blood, and the instructions can differ slightly between these tests.

Lab Tests Online UK notes in its stool culture guide that the freshness of the sample is the most important factor for culture, because bacteria in stool continue to grow after collection. It also notes that contamination with urine, toilet water or the inside of a nappy can inhibit bacterial growth and affect the result. The East Kent leaflet says that failing to follow the instructions will make it difficult for your doctor to interpret the results and that you may have to do the test again.

A public health study in the South West of England described in a Public Health England press release (since withdrawn) interviewed 26 patients and identified embarrassment, fear of the results, concerns about hygiene and lack of information as the main barriers to returning samples. Clear instructions are therefore part of the test.

Read all the instructions you have been given. Your doctor or nurse will normally provide a sterile sample tube, often with a small spoon built into the lid. The East Kent leaflet says that if the label has not already been completed you should write on it your first name, surname and date of birth, and your NHS number if you know it, using a biro.

Gather what you need. The leaflet lists a clean, dry, wide-mouth container such as an empty plastic food container or a potty, or some plastic wrap or clean newspaper, together with a bin bag and soap and water. The national guidance reproduced in the PHE press release adds that if you need to urinate you should do so first and then collect the stool sample, and that you can use any clean container you can seal if you do not have one from your doctor.

If your clinician has given any special instruction, for example for a particular test, follow that. The national guidance says to follow any other instructions you are given.

• The sterile tube and, if provided, a request form and sealable bag.

• A clean, dry, wide-mouth container, or plastic wrap or newspaper.

• A bin bag, soap and warm water.

• A biro to complete the label.

The East Kent leaflet sets the steps out in order. Place the container or potty in the toilet bowl, or place clean newspaper or plastic wrap across the toilet seat opening. If the stool is very watery you may not be able to use newspaper or plastic wrap. Pass the stool into the container or onto the paper or wrap, making sure it does not touch the inside of the toilet.

Transfer small scoopfuls of the stool into the sample tube with the spoon in the lid. Make sure parts that look bloody, slimy or watery are included, along with some solid material. Do not overfill, put on the lid and screw it on tightly. If the outside of the tube is dirty, clean it with soap and warm water.

Write the date and time on the tube, place it in the plastic bag attached to the laboratory request form and make sure the bag is sealed. Flush leftover stool down the toilet. Wrap used newspaper, plastic wrap or disposable containers, put them in a bin bag, tie it and place it in your outside bin. If you used a potty, clean it with your usual toilet cleaner. Wash your hands thoroughly with soap and warm running water, then dry them.

Take the sample and the request form to your GP surgery or the pathology laboratory as soon as possible. The East Kent leaflet says if you cannot deliver it the same day, keep it somewhere dry and away from heat or direct sunlight and do not refrigerate. Lab Tests Online UK, writing about stool culture specifically, says to send the sample as soon as possible and to keep it in the fridge if there will be a delay.

These two instructions conflict, which is a reminder that different laboratories and different tests have their own requirements. If your tube, form or leaflet gives a storage instruction, follow it, and if you are unsure ask the surgery or laboratory when you collect the tube. Some tests need protection from light or a particular container, and your clinician will say so.

If you need replacement tubes, East Kent says new specimen tubes are available from the laboratories or your GP surgery. The laboratory sends the result back to the doctor who requested it, and the East Kent leaflet says most results are available within 1 to 2 weeks, although some take up to 6 weeks and that laboratory staff cannot discuss results with you.

If your stool is loose or watery, collecting it can be difficult. The East Kent leaflet notes that newspaper or plastic wrap may not work in that case, so a clean container or potty placed in the toilet is the better approach. Keep any bloody, slimy or watery parts in the sample rather than discarding them.

If you are collecting a sample from a baby or child, Lab Tests Online UK advises that for an infant in a nappy you should take care to collect the sample without touching the inside of the nappy, because nappies often contain substances that can interfere with bacterial growth.

A sample request should not delay seeking help. The NHS lists bloody diarrhoea, diarrhoea for more than 7 days, vomiting for more than 2 days, signs of dehydration and concerns about a baby under 12 months among the reasons to call 111, and a sample can be collected while you do so.