Skip to main content


Nasopharyngeal wash


For patients with weak immune systems, a runny nose, cough, and congestion can be signs of an infection caused by a virus (germs that can pass from one person to another). For the best outcome, viral infections should be treated in their early stages. Each type of virus requires a certain treatment. Identifying the virus is the best way to know which treatment to use. To identify the virus, we must collect a sample of the cells from the nasopharynx (nay zo FAR inks) and look at those cells under a microscope. The nasopharynx is a space behind the throat and connected to the nasal passage. The cells collected from this area are called epithelial (e pi THEE lee al) cells.

Nasopharyngeal wash

How are samples collected?

To collect a sample of epithelial cells from a patient, a soft, flexible catheter (tube) is attached to a syringe filled with saline (sterile salt water). A staff member then places the tube in the nose and gently inserts it into the nasopharynx. A small amount of saline is flushed into the nasopharynx through the tube. Then, the staff member pulls back on the syringe to collect a sample of epithelial cells.

This nasopharyngeal (nay zo fa RIN jee ul) wash is used to help loosen the cells so it is easier to collect the sample. Your child’s age and size will help the staff know how much saline to use.

What happens during a nasopharyngeal wash?

When it is time to collect a sample, a staff member will ask your child to lie on his back with his neck extended. Having the neck extended allows the saline to pool at the back of the nasopharynx. Just before the catheter is placed in the nose, your child will be asked to hold his breath. When the catheter is in place, the staff member will push the plunger of the syringe to send the saline through the tube then rapidly pull back on the syringe removing the saline along with the sample of cells.

This wash allows the staff member to get a big enough sample for the lab to process.


To learn more about how epithelial cell samples are collected, talk to your child’s nurse or doctor.


This document is not intended to take the place of the care and attention of your personal physician or other professional medical services. Our aim is to promote active participation in your care and treatment by providing information and education. Questions about individual health concerns or specific treatment options should be discussed with your physician.

St. Jude complies with health care-related federal civil rights laws and does not discriminate on the basis of race, color, national origin, age, disability, or sex.

ATTENTION: If you speak another language, assistance services, free of charge, are available to you. Call 1-866-278-5833 (TTY: 1-901-595-1040).

ATENCIÓN: si habla español, tiene a su disposición servicios gratuitos de asistencia lingüística. Llame al 1-866-278-5833 (TTY: 1-901-595-1040).

تنبيه: إذا كنت تتحدث باللغة العربية فيمكنك الاستعانة بخدمات المساعدة اللغوية المتوفرة لك مجانا. .يرجى الاتصال بالرقم. 5833-278-866-1  (الهاتف النصي: 1040-595-901-1).