A hematoma is a collection of blood beneath the skin. It is the most common adverse reaction to venipuncture. Many factors can contribute to the formation of a bruise.
Venipuncture technique
If the phlebotomist pushes the needle too far into and through the vein, blood leaks out of that opening and into the surrounding tissue. The appearance of a blue or purple discoloration at the venipuncture site indicates the presence of a hematoma. This discoloration at the site may occur immediately or sometime after the venipuncture is completed. A bruise may cause slight discomfort for the patient, but the mere sight of a bruise may generate undue anxiety and discontent for some patients. A patient may associate a bruise with a negative venipuncture experience and be hesitant to have blood tests in the future.
The phlebotomist shouldn't perform a venipuncture at the site of a recent bruise as this may cause discomfort for the patient and affect the quality of the blood sample.
Bleeding disorders and anticoagulant medications:
A hematoma may also form after a venipuncture if the patient has a medical condition that impairs clot formation. For example, a patient on anticoagulant therapy will experience a delay in clot formation. If the phlebotomist is aware of the condition, they can reduce the incidence of hematoma by applying pressure to the venipuncture site for extended periods. Also, it is best to inform the patient that bruising is likely. Communication is essential to relieve patient anxiety if a hematoma appears.
