Blood: Assessment, Diagnostic, and Lab Tests

Assessment: Examine the skin. You must look at it and touch it.

Pallor-paleness. Associated with anemia and shock.

Petechiae-tiny purple or red flat spots on the skin. Result of hemorrhages.

• Purpura-red or purple discolorations on the skin that do not blanch on applying pressure. They are caused by bleeding underneath the skin. Purpura measure 0.3–1 cm (3–10 mm), whereas petechiae measure less than 3 mm, and ecchymoses greater than 1 cm.

Blanching-a temporary whitening of the skin due to transient ischemia (decrease in blood

supply).

Capillary Refill

• the process where blood returns to a portion of the capillary system after its blood supply has been interrupted briefly. Capillary refill is tested by pressing firmly on a fingernail and estimating the time required for blood to return after pressure is released. In a normal person with good cardiac output and perfusion, capillary refilling should take less than 3 seconds. A time of more than 3 seconds is considered a sign of sluggish circulation, and a time of 5 seconds is regarded as abnormal.

Jaundice- a yellow color of the skin, mucus membranes, or eyes. The yellow

coloring comes from bilirubin, a byproduct of old red blood cells.

Phlebotomy-drawing blood from a vein.

ALERT!!!!!

• Before for drawing blood on anyone, always check the order and then make sure you have the right patient.

• Check their hospital ID band and ask them, “Tell me your name and date of birth.”

• Check your facility policy for anything you do to a patient.

Alert: Use universal precautions when drawing blood.

Blood Typing

• Each red cell has a specific combination of factors called antigens and antibodies. (ABO blood group)

• Blood antigens are inherited. Blood antibodies are acquired after exposure to antigens.

• Remember: You can’t get what you don’t have. You have that antigen on your red cell, your body will attack anything that isn’t that antigen. Example: Type A has antigens on cell and will attack B antigens. Type O has no antigens on its cell and will attack A and B antigens.

Blood Typing

Rh factor

Rh Factor

• Besides A and B antigens, many other antigens are located on the surface of a red blood cell. One of these is called the Rh factor (named because it was first found in the blood of a rhesus monkey). The term Rh-positive means a person was born with the Rh antigen on the red cell. An Rh negative person does not have the Rh factor on the cell and may generate anti-Rh antibodies if given Rh positive blood.

Blood Typing• Type and Screen is the

lab test to identify your blood type.

• Type and Cross (Crossmatch) is actually seeing if you will react to a specific unit of blood. Crossmatching is also used in organ donation matching.

Alert

• Check the facility policy about blood typing. Most facilities require two people to sign/identify a lab specimen for blood typing.

• One big difference between RNs and LVNs is the ability to administer blood products. It is beyond the scope of practice for an LVN to hang blood/blood products. Blood transfusions require two RNs to check the unit before administering. Blood transfusions also require and RN to stay in the room and monitor the patient continuously during the first 15 minutes of an infusion. Vitals are taken more frequently also.

Complete Blood Count (CBC)

• Lab test that tells you the number of red cells, white cells, platelets, hemoglobin level, and hematocrit level. Basically, the composition of your blood.

Hemoglobin and Hematocrit (H & H)

• Hemoglobin (Hgb) test- measures the total amount of hemoglobin in a sample of blood. Hemoglobin is an iron-rich protein which enables a red cell to carry oxygen.

• Hematocrit (Hct) test-percentage of erythrocytes in a volume of blood. A sample is spun in a centrifuge so that the erythrocytes can fall to the bottom of the sample.

Hematocrit

Hematocrit Reader

Lab Technicians and Technologists

Platelet Count

• Number of platelets per cubic millimeter (mm3).

• Low platelet counts indicate and increased risk for bleeding. Platelets help blood clot.

Red Blood Cell Count (RBC)

• Number of erythrocytes per cubic millimeter.

• Low RBC may indicate bleeding or anemia.

White Blood Cell Count (WBC)

• Number of leukocytes per cubic millimeter.

• High WBC count indicate a bacterial infection.

• Low WBC count could indicate a virus or cancer.

PT/PTT-studies that measure your ability to stop bleeding (coagulation).

• Prothrombin Time (PT)-Test of the ability of blood to clot. Measures the time elapsed between the addition of calcium and tissue factor (thromboplastin) to a plasma sample and the appearance of a visible clot.

• Partial Thromboplastin Time (PTT)-Measures the presence of plasma factors that act in a portion of the coagulation pathway.

• Patients who are on anticoagulant medications like Coumadin or Heparin will have coagulation studies (PT/PTT) done frequently.

Bone Marrow Aspiration/Biopsy

Bone Marrow Biopsy

• Microscopic examination of a core of bone marrow removed with a needle.

• This procedure is helpful in the diagnosis of blood disorders such as anemia and leukemia.

• Bone marrow may also be removed by brief suction produced by a syringe, which is termed a bone marrow aspirate.