Sex chromatin test

Alternative names
Buccal smear

Definition
A buccal smear is a painless test in which cells are taken from the tongue and evaluated for the presence of Barr bodies (a type of mass seen in normal female sex chromosomes).

How the test is performed
Cells are collected by scraping the tongue with a spatula. The cells are then placed on a slide and sent to a laboratory for evaluation.

How to prepare for the test
No preparation is necessary for this test.

How the test will feel
You will feel a scraping sensation as cells are removed from the tongue.

Why the test is performed
In the past, this test was used to indicate:

     
  • Abnormal sexual development  
  • Ambiguous genitalia  
  • Amenorrhea  
  • Suspected chromosomal abnormalities

Today, a health care provider who suspects any of these abnormalities is most likely to perform a full chromosome analysis (called karyotyping) rather than a buccal smear.

The buccal smear is primarily used in the Olympic Games or other sporting events if the authorities believe a man is trying to compete as a woman.

Normal Values
The normal result for a female is an indication of the presence of Barr bodies, confirming the gender as female.

What abnormal results mean
If no Barr bodies appear, the test subject is a male.

What the risks are
There are no risks associated with the buccal smear.

Johns Hopkins patient information

Last revised: December 5, 2012
by David A. Scott, M.D.

Medical Encyclopedia

  A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | 0-9

All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.