Navigate Up

Pediatric Center - A-Z Index

#
Q
Z

Print This Page

Blood smear

A blood smear is a blood test that gives information about the number and shape of blood cells.

Alternative Names

Peripheral smear

How the test is performed

A blood sample is needed. For information on how this is done, see: Venipuncture

The blood sample is sent to a lab, where the health care professional looks at it under a microscope. Or, the blood may be examined by an automated machine. The smear shows the number and kinds of white blood cells (differential ), abnormally shaped blood cells, and gives a rough estimate of white blood cell and platelet counts.

How to prepare for the test

No special preparation is necessary.

How the test will feel

When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging sensation. Afterward, there may be some throbbing.

Why the test is performed

This test may be performed as part of a general health exam to help diagnose many illnesses. Or, your doctor may order this test if you have signs of a blood disorder.

Other conditions under which the test may be performed:

Normal Values

Red blood cells normally are the same in size and color and have a lighter-colored area in the center. The blood smear is considered normal if there is:

  • Normal appearance of cells
  • Normal white blood cell differential

The examples above are common measurements for results of these tests. Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples.Talk to your doctor about the meaning of your specific test results.

What abnormal results mean

Abnormal results mean there is an abnormality in the size, shape, color, or coating of the red blood cells.

Some abnormalities may be graded on a 4-point scale:

  • 1+ means 25% of cells are affected
  • 2+ means half of cells are affected
  • 3+ means 75% of cells are affected
  • 4+ means all of the cells are affected

The presence of target cells may be due to:

The presence of sphere-shaped cells (spherocytes) may be due to:

The presence of elliptocytes may be a sign of hereditary elliptocytosis or hereditary ovalocytosis .

The presence of fragmented cells (schistocytes) may be due to:

The presence of a type of immature red blood cell called a normoblast may be due to:

The presence of burr cells (echinocytes) may indicate:

The presence of spur cells (acanthocytes) may indicate:

The presence of teardrop-shaped cells may indicate:

  • Leukoerythroblastic anemia
  • Myelofibrosis
  • Severe iron deficiency
  • Thalassemia major

The presence of Howell-Jolly bodies may indicate:

The presence of Heinz bodies may indicate:

  • Alpha thalassemia
  • Congenital hemolytic anemia
  • G6PD deficiency
  • Unstable form of hemoglobin

The presence of slightly immature red blood cells (reticulocytes) may indicate:

  • Anemia with bone marrow recovery
  • Hemolytic anemia
  • Hemorrhage

The presence of basophilic stippling may indicate:

The presence of sickle cells may indicate sickle cell anemia.

What the risks are

Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.

Other risks associated with having blood drawn are slight but may include:

  • Excessive bleeding
  • Fainting or feeling light-headed
  • Hematoma (blood accumulating under the skin)
  • Infection (a slight risk any time the skin is broken)

Special considerations

The accuracy of this test depends, in part, on the experience of the person looking at the sample. Experienced cell examiners can get a lot of information from the blood smear.

References

Cecil Medicine

Updated: 2/8/2012

Todd Gersten, MD, Hematology/Oncology, Palm Beach Cancer Institute, West Palm Beach, FL. Review provided by VeriMed Healthcare Network. Also reviewed by Linda J. Vorvick, MD, Medical Director and Director of Didactic Curriculum, MEDEX Northwest Division of Physician Assistant Studies, Department of Family Medicine, UW Medicine, School of Medicine, University of Washington; David Zieve, MD, MHA, Medical Director, A.D.A.M. Health Solutions, Ebix, Inc.


©  UPMC | Affiliated with the University of Pittsburgh Schools of the Health Sciences
Supplemental content provided by A.D.A.M. Health Solutions. All rights reserved.

For help in finding a doctor or health service that suits your needs, call the UPMC Referral Service at 412-647-UPMC (8762) or 1-800-533-UPMC (8762). Select option 1.

UPMC is an equal opportunity employer. UPMC policy prohibits discrimination or harassment on the basis of race, color, religion, ancestry, national origin, age, sex, genetics, sexual orientation, marital status, familial status, disability, veteran status, or any other legally protected group status. Further, UPMC will continue to support and promote equal employment opportunity, human dignity, and racial, ethnic, and cultural diversity. This policy applies to admissions, employment, and access to and treatment in UPMC programs and activities. This commitment is made by UPMC in accordance with federal, state, and/or local laws and regulations.

Medical information made available on UPMC.com is not intended to be used as a substitute for professional medical advice, diagnosis, or treatment. You should not rely entirely on this information for your health care needs. Ask your own doctor or health care provider any specific medical questions that you have. Further, UPMC.com is not a tool to be used in the case of an emergency. If an emergency arises, you should seek appropriate emergency medical services.

For UPMC Mercy Patients: As a Catholic hospital, UPMC Mercy abides by the Ethical and Religious Directives for Catholic Health Care Services, as determined by the United States Conference of Catholic Bishops. As such, UPMC Mercy neither endorses nor provides medical practices and/or procedures that contradict the moral teachings of the Roman Catholic Church.

© UPMC
Pittsburgh, PA, USA UPMC.com