HSBTE 2nd Semester DMLT Collection and Preservation of Clinical Specimens for Biochemical Analysis of Urine and Stool.

URINE COLLECTION

Collect fasting midstream urine in a clean and dry container. It means discarding the first portion of urine and the last portion of urine. Always wash properly penis glans in the case of male patients and vulva in the case of female patients before collection of urine. This urine sample is used for qualitative analysis of urine. For quantitative analysis of urine, collect 24 hours of urine. Urine specimens should be used within 24 hours for testing purposes.

URINE PRESERVATION

Urine can be preserved in the refrigerator at an acidic pH of 6 without using any preservative. However, chemical preservative prevents chemical deterioration in urine and microbial growth in urine. Toluene is the best preservative to preserve urine. Other examples are boric acid 1gm in 100 ml urine, concentrated hydrochloric acid 1 ml in 150 ml urine, and formalin or chloroform 1 drop for 15 ml urine. Sodium fluoride 5 mg in 100 ml urine.

STOOL COLLECTION

The stool specimen to be collected may be formed stool (solid stool), soft stool (semisolid stool), diarrheal stool, or watery stool. Formed stool is a normal stool while other forms of stool are abnormal stool.

Containers: Various types of containers are used to collect stools. The container is selected depending on the quality of the stool. Types of containers are disposable wide-mouth plastic or glass bottles, waxed cardboard boxes, or glass jars with lids. A sterile container should be preferred to collect stool. Sterile collection kits can be procured from the local pharmacy or the health care provider. This kit consists of a sterile container, a pair of sterile disposal gloves, and a sterile collection scoop or stick. Formed stool or dry stool can be collected in the waxed cardboard box. But it is not suitable for the other forms of stool such as liquid stool or watery stool. These types of stool are collected in sterile wide-mouth glass or plastic containers with leakproof lids.

Procedure:

• 1. Collect a clean, dry, and sterile suitable container.

• 2. Put on sterile disposable gloves to avoid the contamination of the stool and to protect the skin.

• 3. Remove the lid of the collection container and set aside.

• 4. Collect a small amount of the stool by using a sterile scoop or stick from the middle of the bowel movement. Do not collect the entire stool.

• 5. Place the stool sample directly into a sterile collection container by using a scoop. If using a stick, smear the stick onto the container lid and snap the lid shut.

• 6. Remove gloves and dispose of them in a plastic bag.

• 7. Wash hands thoroughly with soap and water.

• 8. Label the container with name, date of birth, and time of collection.

• 9. Place the container in a sealed plastic bag.

Precautions:

• 1. The stool specimen should be examined within 1 hour.

• 2. Avoid mixing of urine with stool samples.

• 3. Stool specimens should be stored in well closed container to avoid drying.

• 4. The stool specimen container should be labeled with the name of the patient, date and time of collection,

• 5. Unused stool specimens should be disposed of properly.

STOOL PRESERVATION

10% v/v formalin saline is used as a preservative. A Preservative is used to keep the parasite intact inside the stool so that it can be detected during stool examination. Its formulation detail is as below:

• 1. Formaldehyde: 25 mL.

• 2. Normal saline 75 mL.

Dr Pramila Singh.