Specimens, Laboratory Values and Blood Glucose Monitoring

Specimen Collection: Urine, Sputum, Stool, and Cultures

Accurate laboratory results begin with proper collection techniques. When collecting a clean-catch midstream urine specimen, a client with a vulva cleanses from front to back, while a client with a penis cleanses the glans as directed. The client starts voiding into the toilet first and then passes the sterile container into the stream to collect the midstream urine, taking care never to touch the inside of the container. For clients with an indwelling catheter, urine specimens must be aspirated with a sterile syringe directly from the designated collection port after thoroughly cleaning the port with an antiseptic swab; the practical nurse must never take a specimen from the drainage bag.

A 24-hour urine collection requires careful timing to measure the ordered urinary analyte accurately; these tests are not limited to kidney function. The practical nurse reinforces the RN's instructions to discard the first void at the designated start time, record that time, and collect all urine through the same time the next day. All urine produced over the subsequent 24 hours must be saved and stored as directed by the laboratory, which may involve refrigeration, keeping the container on ice, or using a chemical preservative. If even one void is accidentally discarded or missed during the 24-hour collection period, the practical nurse must report this immediately to the RN and consult laboratory directions, which generally require restarting the entire test from the beginning.

Respiratory, stool, and wound cultures require specific handling to prevent contamination. An early-morning sputum specimen before eating or drinking is preferred, but a specimen can be collected at another time when ordered; the client should rinse the mouth with water before collection. The client should rinse the mouth with water rather than mouthwash and provide an expectorated sample from deep within the bronchi, rather than simple saliva from the mouth. For a guaiac-based fecal occult blood test, stool is sampled from separate areas as directed by the test kit instructions. When checking for ova and parasites, deliver the stool sample promptly to the laboratory or place it in the specified preservative; fresh liquid stool may require immediate examination to detect motile organisms.

When obtaining blood cultures, staff authorized to perform the procedure typically collect two sets from separate venipuncture sites using strict aseptic technique. These cultures should be obtained before the first antibiotic dose is administered whenever possible, without delaying urgently needed therapy. For a routine wound swab culture, the practical nurse cleanses the wound with sterile normal saline and samples viable granulation tissue. The nurse avoids sampling surface exudate or necrotic slough, following the specific ordered method and facility protocol.