Final answer:
When a phlebotomist observes a hematoma developing at the site of a venous blood draw, they should take appropriate action to address it. They should apply pressure to the area to stop the bleeding and prevent further hematoma formation.
Step-by-step explanation:
When a phlebotomist observes a hematoma developing at the site of a venous blood draw, they should take appropriate action to address it. A hematoma is a localized collection of blood outside the blood vessels, usually caused by a ruptured blood vessel during the venipuncture process. The phlebotomist should apply pressure to the area to stop the bleeding and prevent further hematoma formation. They may also need to inform the patient and seek medical guidance if necessary.