Today’s technologies allow testing on an impressively wide variety of samples collected from the human body. Most often, all that is required is a blood sample. However, samples of urine, saliva, sputum, faeces, semen, and other bodily fluids and tissues also can be tested.
Some samples can be obtained as the body naturally eliminates them. Others are quick and easy to acquire because they reside in the body’s orifices. For some, minor surgery and anaesthesia give the doctor access to the required sample.
In the following pages, you will find information on samples that are:
- Eliminated from the body,
- Easy To Obtain, and
- From Within the body.
About Collecting Samples for Testing
Samples That Are Naturally Eliminated
Some samples such as urine, faeces, sputum, and semen are collected as the body naturally eliminates them and often they can be collected by the patient. Young children, however, or patients with physical limitations may need assistance. Usually, collecting these samples is painless, but obtaining them can occasionally be awkward and unpleasant because they involve elimination of bodily wastes or bodily fluids and involve body parts and functions people prefer to keep private.
Sometimes these types of samples can be collected at home or hospital and brought to the laboratory. These facilities are usually designed to reduce sample handling by the patient and minimise embarrassment when providing samples. You may, for example, find a “pass-through” window in the toilet so you don’t have to take the container out of the toilet with you.. You may find printed instructions on how to obtain urine or stool samples posted in the toilet so you don’t have to listen to a nurse tell you explicitly how to obtain a “clean catch” of urine or a faecal sample. Below are examples of types of samples typically collected by the patient. It is very important that all instructions for sample collection are carefully followed. Make sure you understand the instructions before collecting your specimen.
Semen — Male patients ejaculate into a specimen container, which some men find embarrassing or difficult. Usually, men need to refrain from ejaculating for 2 to 7 days before collecting the specimen. The specimen must be kept warm and brought to the laboratory within the time period specified.
Sputum — Patients are instructed to cough up sputum from as far down in the lungs as possible. (A nurse may assist the patient in some situations.)
Stool (faeces) — Patients usually collect this sample themselves during toileting, following instructions to prevent the sample from becoming contaminated from other material in the toilet bowl. Patients may also be told to avoid certain foods during the test period. Depending on the test, patients may be instructed to collect the sample in a container, scoop a small portion into a vial, or smear a small amount on special test paper. Wash your hands well after handling the sample.
Urine — Most urine specimens are collected by having the patient urinate into a container or receptacle. To keep the sample from becoming contaminated by materials outside the urinary tract, patients are given instructions on how to clean the area and void a bit of urine before collecting the specimen in the container. (If a urinary catheter is required, a health care worker is usually responsible for insertion.) Collecting the urine specimen is awkward but not in itself uncomfortable (an infection, however, can create a burning sensation during urination). For certain tests, 24-hour urine samples are collected at home and may need to be refrigerated. Remember to wash hands well after collecting the specimen.
Saliva — This type of sample may be collected using a swab or, if a larger volume is needed for testing, patients may be instructed to expectorate into a container.
Oral fluid — This is slightly different than saliva, although it is also collected from the mouth. For example, a rapid HIV test uses oral fluid. The patient collects the sample by using a special device to swab around their outer gums.
Samples That Are Easy to Obtain
Some samples are collected by simply running a swab over the affected area. Procedures of this type can be performed in a clinic, in your doctor’s surgery, or at the hospital bedside. The sample may be sent to a laboratory for analysis. Throat, nasal, vaginal, and superficial wound cultures, for example, are obtained in this way. The procedures, while they may sometimes be uncomfortable, are generally quick, relatively painless, and have no after-effects.
Examples of such collections include:
Secretions and Tissues from the Female Reproductive System — Samples of vaginal secretions are obtained by running a cotton swab over the walls of the vagina; cervical cells for a Pap smear are obtained using a cotton swab and spatula (called a speculum) or a tiny brush. Both procedures are painless. Endometrial tissue samples are obtained by inserting a thin, flexible, hollow tube into the uterus, during which you may feel a slight pinch or brief cramping. Patients may feel embarrassed or vulnerable because of how these samples are collected. Some patients find the position of the legs uncomfortable, some complain that the stirrups and speculum are cold, and some feel slight pressure as the speculum is inserted. A sensitive approach by the health care professional contributes greatly to the patient’s emotional comfort. If you are physically uncomfortable, try asking for what you need (such as a smaller speculum or “booties” for the stirrups). Also, if you would be more at ease if a woman performs these procedures or if a female health worker is in the room when the procedure is performed, ask your practitioner to arrange one of these options for you.
Secretions and Fluids from the Nose or Throat — The specimen is collected by running a swab over the area of interest. People typically respond to swabbing of their throat with a momentary “gag” reflex. If the throat is sore, the sample collection, brief as it is, can be uncomfortable. Similarly, a nasal swab may be a bit uncomfortable as the swab is inserted and reaches areas inside the nose that are typically never touched. Try to remember that the discomfort is temporary and ask your practitioner if there are ways to minimise any soreness that may result. You may also find it helpful to perform relaxation techniques before, during, or after the procedure.
Samples from Open Wounds and Sores — If a wound or sore is located in the outer layer of skin, the specimen is typically collected on a swab by brushing the swab over the area and gathering a sample of fluid or pus. Touching the open wound area may be temporarily painful since the wound is likely to be tender and sore. If a wound or infection is deep, however, a needle and syringe may be used to aspirate a sample of fluid or pus from the site.
Samples From Within
Some samples can only be obtained by breaking through the body’s protective coverings (e.g., skin). Blood samples and tissue specimens, for example, are obtained in minimally invasive procedures conducted by specially trained doctors, nurses, and medical personnel.
Because of the nature of these collection techniques, some pain or discomfort may be involved. Knowing what the procedure involves may help alleviate some anxiety when having to undergo these types of sample collections. For more on this, see the article Coping with Test Pain, Discomfort, and Anxiety.
Some common examples of these kinds of samples include:
Blood — Blood samples can be collected from blood vessels (capillaries, veins, and sometimes arteries) by trained phlebotomists or medical personnel. The sample is obtained by needle puncture and withdrawn by suction through the needle into a special collection tube. The procedure usually takes just a few minutes and hurts just a bit, typically when the needle is inserted or withdrawn. See Tips on Blood Testing for more information.
Tissue Biopsy — Samples of bodily tissue may be obtained from a number of different body sites such as breast, lung or skin and, depending on the site, may involve varying degrees of invasiveness and pain or discomfort. The time required to perform the procedure and for recovery can also vary greatly. These procedures are conducted by doctors and nurses who have had specialised training. Biopsies can be collected using procedures such as:
Needle biopsy — A needle is inserted into the site and cells or fluid are withdrawn using a syringe. A slight pinch may be felt at the site of needle insertion. Usually no recovery time is required, and slight discomfort may be experienced afterwards.
An open biopsy is a minor surgical procedure in which an incision is made and a portion of tissue is cut from the site. A closed biopsy is a procedure in which an incision is made (usually smaller than an open biopsy) and an instrument is inserted to help guide the surgeon to the appropriate site and to obtain the sample. These biopsies are usually performed in a hospital operating room. A local or general anaesthetic is used, depending on the procedure, so the patient remains comfortable. If a general anaesthetic is used, recovery may take one to several hours.
Cerebrospinal Fluid (CSF) — A sample of cerebrospinal fluid is obtained by lumbar puncture, often called a spinal tap. It is a special but relatively routine procedure. It is usually performed while the person is lying on his side in a curled up foetal position but may sometimes be performed in a sitting position. The back is cleaned with an antiseptic and a local anaesthetic is injected under the skin. A special needle is inserted through the skin, between two vertebrae, and into the spinal canal. The doctor collects a small amount of CSF in multiple sterile vials. Then the needle is withdrawn and a sterile dressing and pressure are applied to the puncture site. The patient will then be asked to lie quietly in a flat position, without lifting his head, for one or more hours to avoid a potential post-test spinal headache. The lumbar puncture procedure usually takes less than half an hour. For most patients, it is a moderately uncomfortable to somewhat painful procedure. The most common sensation is a feeling of pressure when the needle is introduced. Let your doctor know if you experience a headache or any abnormal sensations, such as pain, numbness, or tingling in your legs, or pain at the puncture site.
Other body fluids such as synovial fluid, peritoneal fluid, pleural fluid and pericardial fluid are collected using procedures similar to that used for CSF in that they require aspiration of a sample of the fluid through a needle into a collection vessel, such as a syringe or specimen container. They often require some patient preparation, use of a local anaesthetic, and a resting period following sample collection. For details, see the descriptions for arthrocentesis, paracentesis, thoracentesis, and pericardiocentesis.
Bone marrow — The bone marrow aspiration and/or biopsy procedure is performed by a doctor or other trained specialist. Both types of samples may be collected from the hip bone (pelvis), and marrow aspirations may be collected from the breastbone (sternum). In children, samples may also be collected from a vertebra in the back or from the thigh bone (femur). The most common collection site is the top ridge (iliac crest) of the hip bone. Some patients are given a mild sedative before the procedure, and then the patient is asked to lie down on his stomach or side for the collection and his lower body is draped with cloth so that only the area surrounding the site is exposed. The site is cleaned with an antiseptic such as iodine and injected with a local anaesthetic. When the site has numbed, the doctor inserts a needle through the skin and into the bone. For an aspiration, the doctor attaches a syringe to the needle and pulls back on the plunger. This creates vacuum pressure and pulls a small amount of marrow into the syringe. For a bone marrow biopsy, the doctor uses a special needle that allows the collection of a core (a cylindrical sample) of bone and marrow. Even though the patient’s skin has been numbed, the patient may feel brief but uncomfortable pressure (pulling and/or pushing) sensations during these procedures. After the needle has been withdrawn, a sterile bandage is placed over the site and pressure is applied. The patient is then usually instructed to lie quietly until his blood pressure, heart rate, and temperature are normal, and then to keep the collection site dry and covered for about 48 hours.
You may notice that some tests can be performed on more than one type of sample. For example, glucose testing can be performed on both blood and urine samples. However, the sample used for testing is often determined by the purpose of the particular test: a blood glucose test is used to help diagnose diabetes and monitor blood glucose levels in diabetics while urine glucose is one of the substances tested when a urinalysis is performed, such as when a urinary tract infection or kidney disorder is suspected. Sometimes there are options for the type of sample, such as with HIV antibody testing (blood, urine, and oral fluid screening tests are available) and in other situations, one particular type of sample is required.