Microbiology Specimen Rejection Criteria

This policy defines conditions that would render a specimen unacceptable for processing in Microbiology.

All rejected specimens are documented in the lab computer (LIS) with date, time, and the charge nurse and/or physician notified. The procedure for cancelling an unsatisfactory specimen in the LIS should be followed. Specimens which are processed as they are "one of a kind" or for some other reason should be documented in the computer under specimen comments.

The table below outlines the basic criteria for rejection of requests for microbiology tests. Note: All specimens not processed will be refrigerated by Laboratory Alliance for 3 days before they are discarded as a safeguard against erroneously discarding any irretrievable specimen. The charge nurse and/or physician should always be notified upon receipt of these specimens and this should be documented in the Laboratory Information Systems.



Container not identified

Write "container not identified” and call ordering unit to send someone to verify the ID if the request form is attached to the specimen. Otherwise, do not process unless "one of a kind". See policy below.


Container and request form have different ID's


Document in LIS. Call ordering floor or physician office to send correct request forms or resolve the problem.

Request form

Insufficient information marked on form

Call ordering floor or physician office for additional necessary information



Specimen grossly contaminated.

Call ordering floor or physician to send repeat specimen. If they are unable to re-collect, ask them to come down to clean it in the laboratory. Final resort: clean it with germicide, wear gloves, work in bio-hazard chamber.


Specimen submitted in improper container.

Notify ordering floor or physician office of problem. If unable to re-collect, perform test if possible and make note in LIS that improper container was used. If unable to perform test, document reason in LIS and discard specimen.


Excessive delay between specimen collection and arrival in laboratory.

If specimen was not stored properly, notify ordering unit and request repeat specimen. Do not process unless patient care is likely to be compromised by delay. Note in LIS that delay may result in less accurate results.


Inadequate specimen for number of tests requested

Call physician for priority of requests and to request additional material. Note in LIS that specimen had inadequate volume as reason for lack of performance of certain tests.


Some factor renders specimen inadequate for request.
Examples: sputum on a swab or in tissue paper, stool for ova and parasites with gross barium, visible; specimen placed into formalin; container broke or leaked during transport

Call ordering floor or physician office to inform them of problem. Note the problem in LIS and do not process specimen.


Pooled 24 hour urine or sputum received for culture

Call ordering floor or physician office to inform them that 24 - hour specimens are unacceptable for microbiology. Do not process and send report out with note indicating reason for not performing test.


Dry swab received for culture

Notify ordering floor or physician office that dry swabs are not suitable for culture. Do not process. Sent report out with note indicating reason for not performing test.


Improper specimen for test. Examples: blood in serum tube with clot for malaria smear; slide with material smeared on for culture; pleural fluid for serology test.

Call ordering floor or physician office to verify test request. Do not process, and send documented reason for not performing test in LIS


Unsatisfactory expectorated sputum.

See sputum screening procedure.


Formed stool for C. difficile toxins

See stool rejection policy of C. difficile


Foley catheter tip

Call ordering floor or physician office to inform them that clinically relevant results cannot be obtained from this specimen. Request a urine for culture. Send out report noting the reason for not processing the specimen.


Duplicate specimen (other than duplicate blood)

Send notice that only one of the received specimens will be processed unless the laboratory is notified and reasons are given for processing duplicate(s).


Anaerobic culture requested on improper specimen. Examples: expectorated sputum, voided urine (not suprapubic tap), vaginal discharge, prostatic secretions, gastrointestinal tract (except in blind loop syndrome), oral material, respiratory secretions not collected by needle aspiration or by special plugged double-Lumen catheter device, lochia, environmental material, any specimen exposed to air for extended time.

Notify ordering floor or physician office that the specimen is unacceptable for such a request. Process aerobically only.


Sample submitted for Amplified Molecular tests such as C. diff, GC, chlamydia.

Inappropriate for culture as contaminated with normal vaginal flora

A. Previous specimen negative within 7 days.
B. Previous specimen positive within 28 days.

No Appointment Necessary
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