Description
Overview
The Buccal Smear for Barr Bodies, also known as the Sex Chromatin Test, is a rapid cytogenetic screening test. It detects the presence of an inactivated X-chromosome (Barr Body) in the somatic cells of the cheek. This test is primarily used as an initial screening tool for genetic sex determination and to rule out sex chromosome abnormalities such as Turner Syndrome or Klinefelter Syndrome.
Why take this test?
- Genetic Screening: To assist in determining genetic sex in cases of ambiguous genitalia or delayed puberty.
- Chromosomal Check: To screen for numerical abnormalities of the X-chromosome (e.g., Aneuploidy).
- Non-Invasive: Unlike blood tests, this requires only a gentle scrape of the inner cheek.
How it Works
- Collection: A sterile spatula or cytobrush is used to gently scrape the inner lining of the cheek (buccal mucosa).
- Fixation: The cells are smeared onto a glass slide and immediately fixed with a solution (typically 95% Ethyl Alcohol).
- Analysis: The slide is stained (e.g., with Giemsa or Carbol Fuchsin) and examined under a high-power microscope by a pathologist.
- Interpretation:
- Chromatin Positive: Presence of Barr bodies (typically seen in genetic females – XX).
- Chromatin Negative: Absence of Barr bodies (typically seen in genetic males – XY).
Test Details
- Sample Type: Buccal Smear (Cheek Cells)
- Preparation: Rinse mouth with water prior to sampling. No fasting required.
- Turnaround Time (TAT): 24–48 Hours
- Method: Microscopy (Staining)
Note: This is a screening test. For a definitive diagnosis of complex chromosomal disorders, a Karyotype analysis (Chromosomal Study) may be recommended by your physician.
