In some situations, the phlebotomist will make the decision if a blood specimen will be obtained by dermal puncture or venipuncture. The patient's condition, the age of the patient, the amount of blood needed for testing, and the risks associated with the procedure will help the phlebotomist determine the best method for collection.
However, if the puncture is not performed correctly or an approved site is not used, the puncture may cause more discomfort or even injury to the patient.
The risk of accidental needlestick injury to the patient and phlebotomist is minimal since the puncture device is designed to retract the needle once the puncture is made.
The puncture is quick and standardized for puncture depth. However, the procedure takes longer to complete. This delay in the collection of the blood specimen could result in hemolysis or clotting of the blood or tissue fluid contamination of the specimen and specimen rejection by the laboratory.
The dermal puncture minimizes the amount of blood taken from the patient. This will be important to consider, especially with infants in an intensive care nursery. However, some laboratory tests require larger amounts of blood for testing; in these cases, capillary collection is not an option. Additionally, some tests, such as coagulation studies, cannot be performed on dermal puncture specimens because of their plasma specimen requirement.
If a patient is dehydrated or has poor peripheral circulation, an adequate blood collection from a dermal puncture may not be possible.
When a dermal puncture is performed, it should be noted on the requisition. The concentration of glucose may be higher in blood obtained by dermal puncture, and the concentrations of sodium, total protein, and calcium may be lower.
