Specimens

All laboratory tests require a specimen. Blood, the most commonly used specimen, is most often obtained by nursing or laboratory personnel through venipuncture (puncture into the vein), finger stick (puncture into a capillary), or peripheral arterial or venous lines (Fig. 14-2). An additional source of blood is the umbilical cord. A “cord blood” specimen may be ordered for patients in the labor and delivery unit and is collected by nursing personnel.

Blood specimens may have to be collected in different containers depending on the test ordered. For example, coagulation studies and chemistry studies must be taken in different tubes. Cultures performed on blood for different types of organisms (aerobic versus anaerobic bacteria) may require different tubes. Clear and complete information on all tests to be collected reduces the need for additional blood specimens to be drawn. When asked by a nurse to call the laboratory to inquire about amount or means of collecting a specimen; document the information and the name of the person providing the information. It may be helpful for the HUC to include additional information about routine tests whose specimens can be drawn at the same time as the specimen for a stat test in order to reduce the number of blood draws a patient may need to undergo.

Other specimens for testing include urine, stool, sputum, sweat, wound drainage, discharge from body openings, and gastric washings (lavage). Nursing staff members usually collect these specimens (Fig. 14-3).

The doctor usually obtains specimens by entering parts of the body or a body cavity. Types of specimens and the names of the procedures used to obtain them are listed in Table 14-1. A written consent is required to be signed by the patient before invasive procedures including any paracentesis (a surgical puncture and drainage of a body cavity), amniocentesis, lumbar puncture, or other invasive procedures listed are performed, except for pelvic examination. (Review “Preparing a Consent Form,” Chapter 8.) It may be the HUC’s responsibility to order trays, such as a lumbar puncture tray, or other equipment from the central service department (CSD) for the doctor to use to perform these procedures.

All specimens obtained by the nursing staff or doctor usually will be bagged and labeled (not always possible during an emergency) before they are handed to the HUC. It is recommended that the HUC keep plastic gloves in a drawer to use when specimens are not bagged and wash hands after handling specimens (even when placed in plastic bags). The label should include the date and time collected, along with the initials of the person who collected the specimen, in addition to patient information.

Requisitions for laboratory tests of specimens obtained by the nursing staff or doctor may be kept on the nursing unit until the specimen has been collected or the order has been entered into the computer when the specimen is sent. The requisition or computer printout of the order is attached to the specimen bag, and then it is sent to the laboratory. If CPOE is used, then a requisition or other document may need to be printed by the HUC. It is essential that the HUC check the patient name on the specimen and on the computer order screen and compare it with the doctor’s order. Mislabeled specimens usually are discarded and the specimen redrawn, causing a delay in diagnosis and treatment and causing the patient additional discomfort.

It is often the HUC’s responsibility to take the specimen to the laboratory. This should be done as soon as possible. Some specimens (well wrapped) may be sent by the pneumatic tube system, especially when results are needed quickly (e.g., emergency department, surgery). Specimens that should not be sent by the pneumatic tube system are those that have been collected by an invasive procedure, such as cerebrospinal and amniotic fluids. When blood or urine is sent by the pneumatic tube system, specimens must be well wrapped and cushioned. Some facilities may have a policy that disallows any specimen from being transported via the pneumatic tube system because of possible loss or spilling of the specimen.

Point-of-Care Testing

Many laboratory specimens that were once collected and analyzed only in the laboratory department may now be performed on the nursing unit. A laboratory test whose specimen is collected and analyzed on the hospital unit by nursing personnel is called a point-of-care lab test. Because of point-of-care testing (POCT), the procedure for ordering a test may change.

Results are obtained via several methods. These include analysis by portable automated analyzers, the use of reagents (chemicals), and microscopic visualization.

Portable automated analyzers may be used in departments that require immediate results; these decrease the need for stat specimens to be sent to the laboratory. Some tests that may be done on the unit by this method include electrolytes, blood glucose, blood urea nitrogen (BUN), hemoglobin, and hematocrit. A test to evaluate pulmonary function (see Chapter 16), called arterial blood gases (ABGs), may be run by an automated analyzer on the unit.

Reagent-based tests may include a test for pregnancy or human chorionic gonadotropin (hCG) or activated clotting time (ACT), and a test for Helicobacter pylori (CLO – Campylobacter-like organism) test, a bacterium that has been indicated in ulcers of the gastrointestinal system. The CLO test actually uses a biopsy specimen obtained in the endoscopy department (see Chapter 16) and may yield positive results within 2 hours.

Some of the reagent-based tests that are considered point-of-care lab tests are those that are traditionally carried out by nursing personnel; these include blood and urine monitoring for the presence of ketones and for levels of glucose. Blood glucose monitoring is discussed in Chapter 10. The D-dimer coagulation study may be done with a finger stick specimen on the unit. Guaiac, Gastroccult, or Hemoccult tests, which use reagents to detect occult blood (undetectable to the eye) in gastric and stool specimens, are considered point-of-care tests in some health care facilities.

A test that uses both a reagent and microscopic visualization is the fern test, which is used to indicate the presence of amniotic fluid (as a result of rupture of the amnion). The reagent portion uses a strip of paper that indicates acidity (pH paper), and the microscopic portion detects the characteristic fern pattern of crystallized amniotic sodium chloride (salt).