Role of a patient in determining the accuracy and reliability of test reports

Dr Th Dhabali Singh *

There are many factors determining the accuracy and reliability of a laboratory test result. One of the most important factors would have to be the patient himself. After all, it is the sample from the body of the patient - blood, urine, sputum or other specimen - on which the test will be done in the laboratory.

Again, in some radiological investigations, there are certain strict instructions to be followed by the patient prior to the imaging test. This is to ensure that the results will be useful and interpreted correctly by the treating physician.

A patient must ensure the following for an accurate and reliable test result:
o Follow instructions. For many tests, there are strict instructions to be followed before the sample is taken for testing. Some tests require an overnight fasting or there are tests that done on specific intervals or time of the day.
o Alert the laboratory personnel for any deviation from the instruction.A patient needs to inform the healthcare provider or the laboratory personnel for any deviation from the instructions for a meaningful interpretation of the results.
o Inform the laboratory of any medications (including vitamins and supplements) that one is taking. This information will be useful for a correct interpretation of the results by the laboratory personnel and the healthcare provider.
o Other additional information. A patient should inform the laboratory personnel about anyillness history, dietetic or pregnancy status of a woman.

ADHERENCE TO INSTRUCTIONS

Certain behaviours may affect some test results, such as recent or excessive exercise, not taking enough fluids (dehydration), excessive eating, or recent sexual activity. A patient may be asked to refrain from some of these activities for certain tests. Majority of the tests do not require any special instruction to be followed. However, for those that have instructions, they need to be strictly followed.

If a patient is unclear about any of the instructions, the laboratory personnel should be asked to explain them properly. When no instructions are given, a patient should always ask if there are any instructions needed to prepare for the test. A laboratory has pre-printed instructions for certain tests, and a patient should ask the laboratory people to give these printed instructions when they are not handed out to him.

One of the most common type of preparations required for testing is fasting for several hours or overnight before the sampling is done. There are some tests that require a patient to increase or decrease the amount of water to drink for 10 to 12 hours before the test.

Some medications or foods need to be strictly avoided. There are some tests that prohibit a patient from taking tea or smoking. For those samples that are collected at home by the patients themselves (urine, stool, sputum, semen, etc.), the patient could be asked to follow certain procedures and to collect the samples in specific containers. There might be instructions about the timing of collection and the transportation of sample.

SOME EXAMPLES OF TESTS THAT REQUIRE PATIENT PREPARATION

o Glucose tolerance, fasting and two-hour past-prandial (PP) blood sugar tests: Fasting meals or eating at specific times are required.
o Lipids (triglycerides, cholesterol, etc.): Fasting for 8-12 hours may be required.
o Faecal occult blood test:Certain foods and medications might need to be restricted.
o Urine culture: A patient may be instructed not to urinate for at least an hour before the test or to drink a glass of water 15-20 minutes before sample collection or to collection the mid-stream urine.
o Cortisol: Resting before sample collection may be required.
o Pap test (Pap smear): A woman may be instructed not to douche or tube bath for 24 hours before the Pap test is to be performed and not to use any vaginal cream 48 hours prior to the test; the woman is asked not to schedule the test during her menstrual period.
o Ultrasound investigations:Ultrasound is a morphologic and real-time scan. Not all but some ultrasound studies like that of the whole abdomen requires the patient to be on empty stomach.
o X-ray: Barium enema and IVP studies require the patient to come on fasting mode along with proper bowel preparation.

The information whether a patient needs prior preparation or not needs to be ascertained from the laboratory personnel to save oneself from the inconvenience to forgo or delay a test because of lack of necessary preparation.

HOME SAMPLES AND THE NEED FOR SPECIFIC CONTAINERS FOR SAMPLE COLLECTION

There are some tests for which the samples are also collected at home - urine, sputum, stool, semen. All these require specific containers for collection of samples and certain guidelines to be followed in the way the sample is collected. A patient should ensure that all the instructions are followed accordingly.

PATIENT COOPERATION AND ACCURATE RESULTS

Laboratory testing, like other aspects of medical care, requires that the patient is open and honest with the healthcare providers. Just as a patient gives a complete personal information, medical and family history, he or she may need to report deviations from preparation instructions and any medications that one is taking at the time of testing as these may affect the results. Providing complete and accurate information will help ensure reli-. ability of the test results for a better diagnosis and treatment.