Collection, Storage And Shipment Of Specimens For Laboratory ... - NCBI

I. Clinical specimens for IgM and IgG antibody detection

Clinical samples for the diagnosis and surveillance of measles and rubella should be obtained at the first contact between the patient with the clinical case and the health care system, irrespective of the stage of disease at which the patient presents. Depending on the country, blood obtained by venipuncture, dried capillary bloodspots on filter paper and/or oral fluid may be used.

I.A. Whole blood for IgM and IgG antibody detection

Blood collection for serum by venipuncture and handling

Blood should be collected in a sterile tube (5 ml for older children and adults and 1 ml for infants and younger children) and labelled with the patient's name and/or identification number and the collection date.

Whole blood can be stored at 4–8°C for up to 24 hours before the serum is separated, but it must not be frozen.

Whole blood should be allowed to clot and then centrifuged at 1000 × gravitational units (g) for 10 minutes to separate the serum. If there is no centrifuge, the blood can be kept in a refrigerator (4–8°C) until there is complete retraction of the clot from the serum (no longer than 24 hours).

The serum should be carefully removed with a fine-bore pipette to avoid extracting red cells, and transferred aseptically to a sterile vial labelled with the patient's name or identifier, date of collection and specimen type.

A measles/rubella laboratory request form should be fully completed when the specimen is collected and must accompany all specimens sent to the laboratory (Fig. 1).

Fig. 1

Measles and rubella laboratory request and result form. Notes: a The Specimen No. should be exactly as written on the sample container.

Storage and shipment of serum samples

Serum should be stored at 4–8°C until shipment takes place, or for max. 7 days.

When kept for longer periods, serum samples should be frozen at −20°C or lower and transported to the testing laboratory on frozen ice packs. Repeated freezing and thawing of serum samples for IgM testing should be avoided, as it may have detrimental effects on the stability of IgM antibodies.

As a general rule, serum specimens should be shipped to the laboratory as soon as possible. The shipment should not be delayed for the collection of additional specimens.

Serum specimens, in their uniquely labelled, sealed vials, should be placed in sealable plastic bags or pouches containing absorbent materials such as cotton wool to soak up any leakage that may occur (Fig. 2).

Fig. 2

Example of packaging of a serum sample for shipment.

Styrofoam boxes or an insulating (vacuum) flask should be used to contain the sealed bags or pouches. The specimen form and investigation form for each specimen should be placed in a separate plastic bag and taped securely to the inner surface of the top of the styrofoam box or the outside of the vacuum flask (Fig. 3).

Fig. 3

Example of packing several sera into one container for shipment.

If ice packs (which should be frozen) are used, they should be placed at the bottom and along the sides of the styrofoam box. The samples should then be placed in the centre and more ice packs placed on top.

A shipping date should be arranged between the sample collectors and the laboratory. When arrangements have been finalized, the addressee should be informed of the time and manner of transportation. More details on the packaging and transportation of samples are provided in the Manual for the laboratory diagnosis of measles and rubella virus infection (1).

I.B. Dried blood spots for IgM and IgG antibody detection

Collection and handling of dried blood spots

Clean each participant's finger (or heel in the case of very young children) with alcohol and prick with a sterile, disposable microlancet.

Collect up to four drops of whole blood on standardized filter paper (such as Whatman Chromatography paper no 3®, Schleicher and Schuell #903® or another high-quality paper).

The filter paper should be marked up, either by hand or laser-printed, in a standard format that includes 14–15 mm circles within which to place the blood drops. Spaces should be marked to write the name, age and sex of the patient, with a space provided to write the laboratory or specimen number (Fig. 4).

Fig. 4

Example of dried blood spot filter paper collection form.

The filter paper should be allowed to dry thoroughly (for at least 60 minutes) at room temperature. Filter papers may be placed in a slide holder or similar receptacle during the drying process.

Storage and shipping of dried blood spots

Each dried filter paper should be wrapped individually in paper, foil or plastic to prevent possible cross-contamination.

Filter papers should be stored away from sunlight and inside a plastic bag to protect them from dust and moisture.

Dried blood spot samples are not considered biohazardous and can be shipped without special requirements or special documentation from the site of collection to the laboratory.

Although samples do not need to be kept refrigerated or frozen during transport, it is advisable to store them in a cool place and transport them to the laboratory as soon as possible.

I.C. Oral fluid for IgM and IgG antibody detection

Collection and handling of oral fluid

Crevicular fluid exuded from the interface between the gums and teeth contains low levels of IgM. A number of swab collection devices (such as the Orocol®) have been developed specifically to collect this fluid from the mouth.

The swabs are designed to be used like a toothbrush and should be rubbed along the gum until the swab is wet. This usually takes one minute.

The wet swab should be placed inside the clear plastic transport tube, which has an area on the outside to write the name and details of the patient and the date of collection.

Some devices have virus transport medium incorporated within the plastic transport tubes, while others require that a small volume of transport medium be added. Specific instructions provided by the manufacturer of the device should be followed.

Storage and shipping of oral fluid

Once a sample has been collected, the device should be sealed according to the manufacturer's instructions.

If the daily ambient temperature is below 22°C, samples should be shipped to the laboratory within 24 hours.

At higher temperatures samples should be kept in a refrigerator (4–8oC) until they can be shipped to the laboratory on ice.

The samples are usually not considered biohazardous and can be shipped without special requirements or special documentation from the site of collection to the laboratory.