Taking stool tests in children is a procedure that requires special preparation. One of the key issues for parents is the correct storage of biomaterial before delivery to the laboratory. Errors at this stage can lead to distorted results, repeated collections and unnecessary worries. The topic is especially relevant for families with small children, where collecting analysis often turns into a real quest.
Unlike adults, children's feces have specific features: higher enzyme activity, rapid changes in microflora and a tendency to decompose. These factors dictate special storage rules. In this article, we will look at how long a sample can be kept in the refrigerator without losing its diagnostic value, what temperature is optimal, and what mistakes parents most often make. We will pay special attention to the nuances for different types of analyzes - from coprogram to studies for dysbacteriosis.
Why it is important to observe the storage periods of feces
The biomaterial begins to change immediately after defecation. In children's feces, decomposition processes proceed faster due to:
- 🧬 High concentration of active enzymes (lipase, protease)
- 🦠 Rapid growth of pathogenic microflora at room temperature
- 💧 Changes in the pH environment (acidification or alkalization)
- 🧪 Destruction of epithelial cells and leukocytes (important for coprogram)
Laboratory studies show that after 4-6 hours at +20°C the quantity in the sample decreases Escherichia coli by 30-40%, and after 12 hours the composition microflora can change dramatically. For tests on worm eggs preservation of the structure of parasites is critical - if stored incorrectly, their shells are destroyed, and the result becomes false negative.
Optimal storage times in the refrigerator
The terms depend on the type of analysis and temperature conditions. Universal rule: for most studies, baby feces can be stored in the refrigerator at +4...+8°C for no more than 12 hours. However, there are important nuances:
| Type of analysis | Maximum shelf life | Optimal temperature | Notes |
|---|---|---|---|
| Coprogram | 8-12 hours | +4…+6°C | Critical for the determination of leukocytes and erythrocytes |
| Analysis for worm eggs | up to 24 hours | +4…+8°C | In a sealed container, without contact with air |
| Dysbacteriosis | 4-6 hours | +2…+4°C | Requires delivery within 2 hours for an accurate result |
| Calprotectin | up to 72 hours | -20°C (freezer) | Single freezing is allowed |
| Carbohydrates | 4 hours | +4°C | Sensitive to oxidation, requires fast delivery |
For analyzes on occult blood i pancreatic elastase times are reduced to 4-6 hours even in the refrigerator. These tests require delivery to the laboratory on the day of collection. If the sample was stored longer than the specified time, be sure to indicate the real interval in the referral form - this will help the laboratory technician correct the interpretation of the results.
Once a year for prevention|Only as prescribed by a doctor|More often than 2 times a year|Never handed over -->
Temperature conditions: what you need to know
Optimal storage temperature - +4…+6°C. This corresponds to the average mode of a household refrigerator (shelf above the vegetable compartment). It is important to avoid:
- ❄️ Freezing (destroys cellular structures, except for special analyses)
- 🔥 Temperatures above +8°C (accelerates the growth of bacteria)
- 🌡️ Sudden changes (condensation spoils the sample)
- ☀️ Direct light (even in the refrigerator - use opaque containers)
Use a household thermometer to monitor the temperature. In most refrigerators, the +4°C zone is located on the middle shelf. The refrigerator door is the worst place: when opened, the temperature there can rise to +10...+12°C.
What to do if the refrigerator does not cool to +4°C?
If your refrigerator does not maintain the temperature below +6°C, use a cooler bag with cold accumulators. An alternative is to place the container in a bowl of crushed ice (keep out the water). Storage time under such conditions is reduced to 6 hours.
⚠️ Attention: If your refrigerator has aNo FrostorAir Flowfunction, place the container in a sealed bag. Air flows speed up the drying of the sample.
Choice of storage containers: what is suitable and what is not
50% of the success of sample preservation depends on the container. Optimal options:
- Sterile containers from the pharmacy with a spoon-spatula (labels ISO 8362-1)
- Glass jars with a screw cap (pre-sterilized)
- Special tubes with a preservative (for tests for dysbacteriosis)
Categorically not suitable:
- 🧻 Cardboard boxes (absorb moisture, not airtight)
- 🥤 Plastic yoghurt cups (the structure of the sample deteriorates)
- 📦 Food containers without a lid (oxidation upon contact with air)
- 🧴 Medicine jars (residues of drugs distort the result)
Container volume should be 2-3 times larger than the sample volume - this prevents the formation of condensation. For loose stool in infants, use containers with a wide neck and a rubber gasket in the lid.
Buy a sterile container at the pharmacy|Sign the container (full name, date, time of collection)|Check the lid for tightness|Do not wash the container before use|Use only disposable ones spoons-->
Typical mistakes of parents during storage
Even when meeting deadlines, parents often make mistakes that nullify all efforts:
- Storing in the freezer without a doctor's instructions - destroys the DNA of parasites and enzymes
- Use of unsterile containers — foreign bacteria appear in the sample
- Adding water or preservatives yourself —changes osmolarity
- Transportation in a bag without cold —after 30 minutes at +25°C sample spoils
- Mixing portions of different times - distorts the daily rhythm of the microflora
A common mistake is collecting analysis after an enema or suppositories. This distorts the pH and enzyme composition If. the child takes antibiotics, probiotics or iron-containing drugs, a test for dysbacteriosis is taken no earlier than 2 weeks after the end of the course.
⚠️ Attention: If the child is breastfed, and the mother changed the diet 3 days before the analysis (for example, added a lot of meat or dairy products), this may affect the fatty acid composition of the stool. Warn the pediatrician about such changes.
Storage features for different ages
The composition and consistency of stool varies depending on the age of the child, which affects storage rules:
| Age | Features of stool | Storage recommendations |
|---|---|---|
| 0-6 months (GV) | Liquid, yellow, pH 5.1-5.4 | Store for no more than 4 hours, use containers with a gel bottom |
| 6-12 months (complementary foods) | Semi-formed, with inclusions food | Collect the morning portion, store for up to 6 hours |
| 1-3 years | Designed, brown, pH 6.0-7.5 | Storage up to 8 hours at +4°C is allowed |
| 3-7 years | Dense, homogeneous, close to an adult | Can be stored for up to 12 hours, as for adults |
For newborns transportation time is critical: if the laboratory is located more than 30 minutes away, use thermal container. For children, stool is more dense, so it can be stored for 2 hours longer than for infants. Newborns are artificially fed. For children under one year old, it is optimal to take the test within 2 hours after collection. If this is not possible, use preservatives (for example, artificial feeding stool is denser, so it can be stored 2 hours longer than that of infants.
What to do if the shelf life has expired
If the sample has been stored longer than permissible period:
- Do not try to “reanimate” it by freezing - this will aggravate the distortions
- Inform the laboratory about the storage time - some tests can be carried out with adjustments
- For coprogram and dysbacteriosis, you will have to collect a new portion
- To test for worm eggs, you can try to deliver a sample marked for long-term storage
In some cases, laboratory assistants can use conservative methods (for example, adding saline solution to dilute the dried sample), but this reduces the accuracy of the result by 40-60%. For PCR tests (for rotavirus, norovirus), the sample becomes completely unsuitable after the expiration of the storage period.
⚠️ Attention: If the child was tested for hospitalization or before surgery, never Don't take risks with an expired sample. It is better to postpone the collection to the next day than to get false results.
FAQ: Frequently asked questions from parents
Is it possible to store stool in the freezer if the test is for dysbacteriosis?
No, freezing destroys living bacterial cultures. For this analysis, it is critical to store the sample at +2...+4°C for no longer than 6 hours. An exception is special transport media (for example, Portagerm), which allow storage for up to 24 hours.
How to collect an analysis if a child goes to the toilet at night?
Use Urine collector with adhesive baseattached to the child's bottom. An alternative is a disposable diaper with a hydrophobic layer (for example Pampers Sleep & Play). Collect the sample immediately after defecation and place it in the refrigerator.
What to do if blood or mucus is visible in the stool?
Such an analysis should be delivered to the laboratory as quickly as possible (ideally within 1-2 hours). Store at +4°C for no longer than 4 hours. Be sure to indicate in the direction the time of collection and the presence of pathological inclusions.
Can the container be reused?
No, even after washing, protein and fatty deposits remain on the walls, which distort the results. Pharmacy containers are disposable and cost 20-50 rubles - the savings here are unjustified.
What if the laboratory requires a fresh analysis, and the child does not go to the toilet?
To stimulate bowel movements in infants, you can massage the abdomen clockwise or use a gas tube. For children over one year old, give Lactulose syrup (in agreement with the pediatrician). Do not use enemas unless absolutely necessary.