Send-Out Testing, Referral Laboratories, and Special Packaging

What Is Send-Out Testing?

Not every test ordered by a provider can be performed in the facility where the blood was drawn. Tests that require specialized equipment, rare reagents, or very low order volume are sent to a referral (send-out) laboratory — often called a reference lab. Common examples include genetic panels, uncommon endocrine assays, and complex molecular tests. As a phlebotomy technician, your role in send-out testing is critical: if the wrong tube is used, the wrong volume collected, or the specimen shipped at the wrong temperature, the result will be invalid and the patient may need to be redrawn.

Reading the Send-Out Test Directory

Every referral lab publishes a test directory — a reference document (print or online) that lists every test they accept. Each entry typically contains:

• Test name and code — the exact name and the lab's catalog number used on the requisition.
• Specimen type — the tube color and additive (e.g., lavender-top EDTA, gold-top SST, royal-blue-top trace-element tube).
• Minimum volume — the least amount of specimen (whole blood, serum, plasma, or urine) the lab will accept. Always collect a little more than the stated minimum to account for processing loss.
• Shipping temperature — ambient (room temperature, typically 15–25 °C), refrigerated (2–8 °C), or frozen (dry ice, −20 °C or colder). Using the wrong temperature is one of the most common — and most damaging — errors in send-out work.
• Stability — how long the specimen remains valid at each temperature. After that window, analytes degrade and results are unreliable.
• Required documentation — requisition form, patient demographic information, insurance or billing data, clinical notes, or a specific consent form for genetic testing.
• Special handling notes — protect from light, do not freeze, spin within a stated time, or send whole blood only.

Before you touch a tube, look up the test. Do not guess.

Shipping Temperatures: Why They Matter

Ambient specimens are stable at room temperature and do not need refrigeration or freezing. Place them in a sealed biohazard bag with an absorbent pad.

Refrigerated specimens must stay at 2–8 °C during transit. Use a validated cold pack (pre-conditioned gel packs) to keep the specimen cool without freezing it. Direct contact with ice can lyse red blood cells or precipitate proteins.

Frozen / dry-ice shipments are required when an analyte degrades quickly at warmer temperatures. Dry ice sublimates rapidly, so packaged volumes and transit times matter. Follow the referral lab's instructions for dry-ice quantity. Never place dry ice in an airtight container — pressure buildup is a safety hazard. Handle dry ice with insulated gloves to prevent skin burns.

Always use the referral lab's approved, validated shipping containers. Using a random cooler from the break room is not acceptable — validation data exist for approved containers only.

Completing the Requisition Form

The send-out requisition travels with the specimen and is the primary communication between your facility and the referral lab. Every field matters:

• Patient full name, date of birth, and a second identifier (MRN or account number).
• Ordering provider name and contact.
• Test name and referral lab code (copy exactly from the directory).
• Date and time of collection.
• Specimen source, if relevant (e.g., timed collection, urine type).
• Diagnosis code or clinical indication — required by many referral labs for test interpretation and by insurers for reimbursement.
• Billing information.

An incomplete requisition can result in the specimen being held or rejected at the referral lab, delaying patient care.

Chain of Custody for Send-Out Specimens

Chain of custody is the documented record of everyone who has had control of a specimen from collection to final reporting. For routine clinical send-outs, this protects the patient (ensuring the right specimen reached the right lab) and the facility (demonstrating proper handling if a result is questioned). For medico-legal specimens — drug screening, paternity, or forensic samples — chain of custody is legally required and must be maintained with specific forms, tamper-evident seals, and witness signatures.

For every send-out hand-off to a courier or shipping carrier, document:

1. Date and exact time of hand-off.

2. Name and company of the courier or carrier.

3. Tracking number or manifest number.

4. Condition of the specimen at hand-off (intact seal, correct temperature indicator).

5. Name of the facility staff member releasing the specimen.

This record is kept in the laboratory information system (LIS) or a paper log. If a specimen is ever lost in transit or questioned, this documentation is your evidence.

Safety Reminders

• Treat every specimen as potentially infectious. Use standard precautions during aliquoting, packaging, and labeling.
• All specimens shipped by air or ground commercial carrier must comply with federal and IATA regulations for infectious substances or exempt human specimens. Your facility's shipping team handles regulatory classification, but you must label your package correctly.
• Never send a specimen without verifying it is properly sealed in a primary container, placed in a secondary leak-proof bag with an absorbent pad, and then placed in an outer shipping container.
• If you are unsure of any requirement, stop and consult the test directory or your supervisor before proceeding. A delayed specimen is far better than an incorrectly handled one.