Importance of patient preparation before a test

Dr Babina Thangjam *

A clinical laboratory is responsible for conducting medical tests that provide valuable information for physician's decision-making process. Laboratory tests not only help diagnose diseases but also aids monitoring and providing the right treatment for patients. In order to guarantee the quality of laboratory test results, the patient should cooperate by preparing themselves for the sample collection. After all, it is the sample from the body of the patient (blood, urine, body fluids, etc.) on which the test will be conducted.

ENSURING CORRECT RESULTS

It is extremely important that the patient do the following to ensure that the results will be useful and interpreted correctly by the health care provider:

O Follow instructions, if there are any, to prepare for the specific test to be conducted.

O Alert the person collecting the sample if he or she has deviated from the instruction and how.

O Inform the health care provider of any medications (including vitamins and supplements) one is taking. This information is useful if the doctor has any questions about the test results.

PREPARING FOR A TEST

Fortunately for patients, most of the laboratory tests do not require special preparation. Very few laboratory tests require the patients to follow certain set of instructions before collecting the sample. Examples of these are fasting, taking the test at a specific time of the day, following a specific diet for a certain period of time, avoiding certain foods, etc. If a patient is unclear about the instructions, one should always ask for a clarification from the health care provider. If instructions are not given, one should always ask if there are any special instructions needed to prepare for the test.

Certain behaviours may affect some test results, such as recent or excessive exercise, not taking in enough fluids (dehydration), excessive eating, or recent sexual activity. One may be asked to refrain from some of these activities for certain tests.

To help remember the preparations needed, the patient should ask for a written copy of instructions, if there are any from the health care provider. As procedures vary from one lab to another, one should always adhere to the requirements of the testing laboratory where he or she is conducting the test.

COMMON TYPES OF PREPARATION

One of the more common types of preparation required for testing is fasting for several hours before the test or even overnight. Fasting is a requirement of some tests, since the level of substances such as glucose can vary during digestion. While fasting, the patients can ingest only water. The patient is not allowed to consume any solid food, or drink beverages such as coffee, juices or tea; water is the only consumption allowed. Chewing gum (including sugar-free) could also affect the test's results, and hence, should be avoided. Medication is permitted, unless the doctor advises otherwise.

If one is collecting the specimen at home, he or she could be asked to follow certain procedures to transport the specimen from home to laboratory.

EXAMPLES OF LABORATORY TESTS THAT REQUIRE ADVANCE PREPARATION

Some examples of common laboratory tests that require special preparation are:

O Glucose tolerance, fasting, and two-hour past-prandial (PP) blood glucose tests: fasting or eating meals at specific times may be required.

O Serum lipids (triglycerides, cholesterol, etc.): fasting for 8-10 hours is usually required.

O Faecal occult blood test: certain and/or medication restrictions may be required.

O Cortisol: resting before sample collection.If a saliva sample is to be collected, it may be necessary to refrain from eating, drinking, or brushing teeth for a period of time prior to the test.

O Whenever a culture such as urine, sputum, faeces, etc. is asked, the sample should be collected before taking any antibiotic as it may hinder bacteria growth.

PATIENT PREPARATION FOR IMAGING TESTS

Strict instructions and guidelines are also needed for imaging investigations like x-ray, CT scan, ultrasound, MRI, mammogram, etc. Other than general instructions, depending upon the type of investigation required, special instructions are given to the patients which may require fasting too. Strict guidelines are followed for diabetic patients, pregnant women, infants, etc.

There are also certain considerations prior to the administration of contrast – history of allergies, asthma, diabetes, pregnancy, breastfeeding, etc. Some investigations require sedation and hence, a comprehensive clinical history of the patient along with certain tests prior to the investigation may be needed.

CONCLUSION

With laboratory testing, like other aspects of medical care, it is crucial that the patient is open and honest with the health care provider. Just as they should give the laboratory their complete personal, medical, and family history, he or she may need to report deviations from preparation instructions and/or medications taken at the time of testing, as these can affect the results. Providing complete, accurate information will help ensure the reliability of the test results.