Medically reviewed by Dr. Farhan Mukhtar, M.B.B.S., M.Phil (Pb.), Consultant Chemical Pathologist, Al-Nasar Lab & Diagnostic Centre. Updated September 2026.
Quick answer: A stool R/E, meaning Routine Examination, checks the sample by eye and under the microscope for parasites, their eggs, pus cells, red cells, undigested fat and mucus. It needs no fasting, and the report is usually same day. A stool culture is a different and slower test that grows bacteria and identifies which antibiotic will work.
Book a stool test: call 0300 0341944 or find your nearest collection centre.
What does a stool examination look for?
| Finding | What it usually suggests |
|---|---|
| Ova and cysts of parasites | Worm or protozoal infection. Giardia, Entamoeba, Ascaris and hookworm are all found here |
| Pus cells | Inflammation or bacterial infection of the intestine |
| Red blood cells | Bleeding or invasive infection. Amoebic dysentery classically shows both blood and mucus |
| Occult blood | Blood not visible to the eye. Important in anaemia and in bowel cancer screening |
| Undigested fat | Malabsorption, which can point to coeliac disease or pancreatic problems |
| Reducing substances | Sugar not being absorbed, common in children with chronic diarrhoea |
| Mucus | Irritation of the bowel lining |
| Consistency and colour | Pale bulky stool suggests malabsorption. Black stool can mean bleeding higher in the gut |
| H. pylori antigen | Tested separately on stool. See our H. pylori guide |
How do you collect the sample correctly?
This matters more than most patients expect. A poorly collected stool sample is one of the most common reasons a test has to be repeated.
- Use the sterile container provided by the laboratory, never a household jar
- Do not let the sample touch urine or toilet water. Both destroy parasites and dilute the sample. Collect into a clean dry container or onto clean paper first, then transfer
- Take the portion that looks abnormal. If there is blood, mucus or a watery part, include it, since that is where the findings are
- Deliver within one to two hours, or refrigerate. Some parasites, particularly the moving forms of Giardia and Entamoeba, die quickly and become unrecognisable
- A fresh warm sample is ideal when amoebic dysentery is suspected, because the laboratory needs to see moving organisms
- Do not use laxatives or enemas before collecting unless specifically instructed
- Avoid testing during menstruation where possible, as blood contamination confuses interpretation
Why are three samples sometimes requested?
Because parasites are not shed continuously. An infection can be genuinely present and absent from today’s sample.
When a parasitic cause is strongly suspected but the first report is negative, standard practice is to examine three samples collected on different days, ideally alternate days. This substantially increases detection.
The same principle applies to occult blood testing, where three separate samples are usually recommended rather than one.
Stool R/E or stool culture, which do you need?
These answer different questions and are often confused.
Stool R/E is microscopy. It finds parasites and shows whether inflammation is present. Fast, usually reported the same day. It is the right test for suspected worms, Giardia and amoebiasis.
Stool culture and sensitivity grows bacteria such as Salmonella, Shigella and Campylobacter, identifies the organism and tests which antibiotics will kill it. It takes 48 to 72 hours because bacteria need time to grow.
Culture becomes important with bloody diarrhoea, high fever, severe or prolonged illness, diarrhoea after antibiotics, in young children, and in anyone immunocompromised. Given rising antibiotic resistance in Pakistan, culture and sensitivity is often the more responsible choice than treating blind.
Why does this test matter particularly here?
Intestinal parasites remain common in Pakistan, and the consequences extend well beyond diarrhoea.
Hookworm causes slow intestinal blood loss and is a genuine cause of iron deficiency anaemia. Someone treated repeatedly with iron tablets that never quite work may have an untreated parasitic infection driving the loss. That is why a stool examination is often ordered alongside iron studies.
Giardia causes bloating, foul smelling stool and malabsorption rather than dramatic diarrhoea, and is frequently mistaken for irritable bowel syndrome for months.
In children, chronic parasitic infection contributes to poor growth and poor concentration at school, and it is easily treated once identified.
When should you have a stool test?
- Diarrhoea lasting more than a few days
- Blood or mucus in the stool
- Persistent abdominal pain, bloating or excessive gas
- Chronic loose stools alternating with constipation
- Unexplained weight loss or failure to gain weight in children
- Iron deficiency anaemia with no obvious cause
- Visible worms, or itching around the anus, particularly in children at night
- Pale, bulky, greasy stool that is difficult to flush
- Diarrhoea following a course of antibiotics
- As part of a food handler or pre employment screening
How to prepare
- No fasting is needed and you should eat normally
- Tell the laboratory if you are taking or have recently taken antibiotics, as they suppress bacterial growth and can produce a falsely negative culture
- Mention antiparasitic medicines, antacids and iron tablets, all of which can affect findings
- For occult blood testing, ask whether any dietary restriction applies
- Collect the sample as close to your laboratory visit as possible
Stool testing at Al-Nasar Lab
Al-Nasar Lab & Diagnostic Centre has provided laboratory testing in Lahore since 1996 and holds ISO 15189:2022 accreditation from the Pakistan National Accreditation Council. Stool routine examination, stool culture and sensitivity, occult blood and H. pylori stool antigen testing are all available, with same day reports for routine examination.
Because chronic digestive symptoms usually need more than one test, stool examination is commonly taken alongside a complete blood count, CRP and ESR and, where indicated, an abdominal ultrasound.
Find your nearest collection centre, see our full test list, or contact us to book.
Frequently Asked Questions
Do I need to fast for a stool test?
No. Eat normally. What matters is collecting the sample cleanly and getting it to the laboratory quickly.
How quickly must the sample reach the laboratory?
Within one to two hours, or refrigerated. Some parasites die quickly and become unidentifiable, which can cause a false negative.
Why do I need to give three samples?
Parasites are shed intermittently, so one sample can miss an infection that is present. Three samples on different days substantially improve detection.
What is the difference between stool R/E and stool culture?
R/E is microscopy for parasites and inflammation, reported the same day. Culture grows bacteria and tests antibiotic sensitivity, taking 48 to 72 hours.
Can a stool test explain my anaemia?
It can. Hookworm and occult bleeding both cause iron loss through the gut, so stool examination is often ordered when iron deficiency has no obvious cause.
This article is for general information and is not a substitute for medical advice. Please discuss your results with a qualified doctor.
