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A hematoma is another name for a bruise. A hematoma or bruise is a collection of blood beneath the skin. Hematomas are the most common adverse reaction to venipuncture. There are many factors that 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 some time 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.

It is not advisable for the phlebotomist to perform a venipuncture at the site of a recent bruise as this may cause discomfort for the patient and may also 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. A patient who is on anticoagulant therapy will experience a delay in clot formation. If the phlebotomist is aware of the condition, he/she can reduce the incidence of bruising by applying pressure to the venipuncture site for a longer than normal period of time. Also, it is best to inform the patient that bruising is likely. Communication is important to relieve patient anxiety if a hematoma appears.