Some tests require precautions to be followed before taking samples to ensure accurate and reliable tests. These precautions include fasting..
Fasting before the Test means:
Do not eat for a certain period of time before taking the sample.
Do not drink anything except water.
Do not chew gum before the test.
Take the required medications for the patient and do not stop taking them except with the permission of the attending physician.
Do not smoke before or during the sample collection.
Different urine samples:
Random sample:
The first morning sample (first sample after waking up) is considered the best sample, but a random sample can be taken at any time of the day. Urine samples should be sent to the laboratory within two hours of collection.
Urine culture sample:
The area around the urinary opening must be washed well with water without drying. The middle sample is collected in a sterile container after removing the first and last parts of the sample from this container.
24 hour urine collection:
A special container is taken from the lab and may contain preservatives.
The patient should start collecting urine at a specific time of the day (for example: at 8 a.m.) and should record the time of collection.
The first sample from the start of the collection is discarded.
The patient then carefully collects the samples in the designated container, taking care not to lose any sample or part of it until the second day, exactly 24 hours after the start of the collection (8 am the next day). Please note that the patient must urinate at the end of 24 hours and add that to the samples.
It is preferable to keep the container in the refrigerator during the collection period and after completion until it reaches the laboratory unless otherwise stated.
The sample must arrive at the laboratory within a maximum of two hours after completion of collection.
Stool samples:
Stool should be collected in a clean, dry container with a tight lid. It is preferable to take three samples over three consecutive days (if possible) to obtain the most accurate results, if a parasitic infection is suspected. Samples should not be contaminated with urine, water or any disinfectant. The sample should be protected from direct sunlight and delivered to the laboratory within one to two hours maximum, depending on its condition. If the sample is liquid, please deliver it to the laboratory within a maximum of half an hour. The examination should be done before starting to take antibiotics or intestinal disinfectants. If an antibiotic is taken, please clarify its type or finish treatment with it and wait 7 days for the analysis, unless the treating physician has a different opinion.
Occult blood in stool:
The patient should not brush their teeth on the day of the sample collection. The test used is very specific and detects only human blood, so there is no conflict with eating meat before the test..
sputum Test:
Patients should drink sufficient quantity of water the day before the test, and should come to the lab in the morning without brushing their teeth.
The sample is collected in a clean sterile container taking into consideration that the specimen is sputum and not saliva.
Different types of cultures:
Patients should stop all antibiotics not less than 3 to 5 days before the test.
If this is not possible, the patient should mention the antibiotic name to the lab staff.
Different types of cultures:
Patients should stop all antibiotics not less than 3 to 5 days before the test.
If this is not possible, the patient should mention the antibiotic name to the lab staff.
Semen analysis:
Before this test, the patient should avoid sexual intercourse for 3-7 days.
The whole sample should be collected in a special sterile container.
The sample should be sent to the lab within 15-30 minutes of sample collection.
Chemical tests of semen:
The sample should be kept in the refrigerator until it is sent to the lab within 1 hour maximum.
Special testing conditions
Number of fasting hours: From 12 to 14.
Trough is taken just before the dose and the peak sample is taken 4 – 5 hours after the dose. N.B: if suspension form of the drug is taken the peak would be after 1.5 hours after the dose is taken. As for carbamazepine XR, peak sample is withdrawn 3-12 hours after dose administration.
Intramuscular injection and physical exercises raises its level in blood.
Trough is taken just before the dose and the peak sample is taken 1-4 hours after the dose.
Trough is taken just before the dose and the peak sample is taken 4-12 hours after the dose. N.B: for infant doses, rapid release and suspension drug formulas, the peak sample is withdrawn 1.5-3 hours after dose administration.
The patient’s weight must be recorded.
2 categories – Fasting test: Where the patient should be fasting for at least 8 hours prior to the test. – Post-prandial: The patient eats his regular meal/75g glucose (after at least 8 hours fast) then a blood test is taken after 2 hours.
The patient should be fasting for 12 hours at least.
The blood sample of a fasting patient is taken first followed by an oral glucose dose of 75 gm. Then a total of 4 blood samples are taken, one every 30 minutes for 2 hours.
Diabetes curve for pregnant women: A sample is taken while the patient is fasting, then she is given an oral glucose dose of 75 gm. Then 3 samples are taken, every 60 minutes for 2 hours. (This test is done between 24-28 wk pregnancy).
This is a test to detect gestational diabetes (Diabetes during pregnancy). The patient is given a dose of 50 gm of glucose then a sample is taken after an hour. Fasting is not essential in this test. (This test is done between 24-28 wk pregnancy).
Diabetes curve for pregnant women: A sample is taken while the patient is fasting, then she is given an oral glucose dose of 100 gm. Then 3 samples each to be taken, every 60 minutes for 3 hours. (This test is done between 24-28 wk pregnancy).
The sample should be sent to the lab in 30 minutes.
The sample should be sent to the lab in 30 minutes.
Patients should come early to the lab and without going to the W.C. The swab is taken from the area surrounding the anus using a scotch tape that is pasted on a slide to be tested. This test is usually recommended to diagnose pinworm infection in children.
A blood sample is taken at 8 a.m. and another sample is taken at 8 p.m.
The blood sample is taken from 8 to 10 a.m.
The patient should lay relaxed on his back for 30 minutes. The patient should- for one week prior to the test- stop medications that contains alpha methyldopa or epinephrine including some nasal drops used for sinusitis. He/she should also stop drugs recommended for coughing, bronchodilators, or appetite suppressants. This test should be performed during episodes of elevated blood pressure.
Fasting C-peptide should be taken after 8 to 10 hours of fasting and post-prandial C-peptide should be taken 2 hours after either a regular meal (eaten in 10-15 minutes) or after 75 oral glucose.
Fasting Insulin should be taken after 8 to 10 hours of fasting and post-prandial Insulin should be taken 2 hours after either a regular meal (eaten in 10-15 minutes) or after 75 oral glucose.
A blood sample is taken at 8 a.m and another sample is taken at 8 p.m.
The sample should be taken on the second or third day of the menstrual cycle.
This test is carried out on the 12:14 week of pregnancy.
This test is carried out on the 14:22 week of pregnancy.
Serum is collected at 8 am for baseline Cortisol. 1 mg dexamethasone orally at 11 pm. Another serum sample at 8 am the following day.
24 hours urine is started to be collected on day 1 and day 4. Dexamethasone, 0.5mg, is given orally every 6 hours starting at 8 am on day 2 (for a total of 8 doses to be taken in 2 days). Serum cortisol is measured on day 1 (at 8 am and 8 pm) to look for diurnal variation.
24 hours urine is started to be collected daily for 6 days. Dexamethasone, 0.5mg, is given orally every 6 hours starting at 8 am on day 3 (for a total of 8 doses to be taken in 2 days). Then dexamethasone, 2 mg, is given orally every 6 hours starting at 8 am on day 5 (for a total of 8 doses to be taken in 2 days).
After an overnight fast, a basal blood sample is taken. The patient then is either given oral clonidine tablets (the dose is determined according to the body weight) or asked to perform a physical exercise (Like climbing stairs for 20 minutes) After that, a blood sample is taken every 30 minutes for 2 hours.
Refrigerate sample throughout and after period of collection. No caffeine intake before or during sample collection. Mono amine oxidase inhibitors should be stopped for 1 week before starting to collect the sample. All precautions for 24 hours urine collection should be followed.
The patient should stop, at least 4 weeks prior to the test, diuretics , liquorice and chewing tobacco. Patient should liberalize (rather than restrict) sodium intake. Patient might have to change his/her hypertensive medications (ACE inhibitors and angiotensin receptor blockers) as they could interfere with test results. Potassium supplements for the patient should be taken for 3 days prior to testing then stopped 24 hours before sampling. (to bring potassium levels to normal) The sample is taken mid-morning before 10 am, after the patient has been up (standing or walking) for at least 2 hours and seated for 5-15 minutes.
The test should not be carried out during or just after the symptoms of hemolysis.
The following conditions should be fulfilled:
Samples should be transported in a glass, plastic or metal container or a plastic bag.
Avoid wrapping the specimen in gauze which tends to produce desiccation.
If there was no preservative or delay in sending(>24hours) specimens to the laboratory, specimens should be kept at 4°c.
Specimen should be placed in fixative (10% buffered formalin) shortly (<30 min) and avoid over fixation (>24-48 hours)
The volume of the fixative should be at least 10 times that of the tissue.
The container should have an opening large enough so that the tissue can be removed easily after it has been hardened by the fixation.
The fixative should surround the specimen on all sides.
Large specimens that float on a fixative should be covered by a thick layer of gauze.
The fixative is carried at room temperature or in case of large specimens at 4°c.
A complete surgical pathology request form including: age, name sex, clinical data, surgical and radiologic data should be provided.
Surgeons should submit the whole biopsy to the laboratory.
Warfarin should be stopped one week prior to the test and heparin is also to be stopped 2 days before the test.
Asprin , Clopidogrel, phenothiazines, antihistamines or any medications that might affect platelet function should be stopped 10 days prior to the test.
Warfarin should be stopped one week prior to the test and heparin is also to be stopped 2 days before the test.
The sample is to be taken by a specialized pathologist and not by anyone in the lab. The patient should bring any radiological tests results.
Patients must abstain from eating nuts, citrus fruit, chocolate, vanilla, banana, coffee and tea for 3 days before collecting the urine sample.
