Specimen Rejection: The Most Common Reasons Labs Reject Samples

Specimen Rejection: The Most Common Reasons Labs Reject Samples

Every blood specimen tells an important part of a patient's story—but only if the sample is suitable for testing. When a specimen is rejected by the laboratory, it can delay diagnosis, postpone treatment, increase healthcare costs, and require patients to undergo another blood draw. Fortunately, many specimen rejections are preventable by following proper collection and handling procedures. Let's look at the most common reasons laboratories reject specimens and what phlebotomists can do to avoid them.

1. Hemolyzed Specimens²

Hemolysis occurs when red blood cells rupture and release their contents into the serum or plasma. Hemolyzed specimens can interfere with many laboratory tests, including potassium, lactate dehydrogenase (LDH), AST, and other chemistry analytes.

Common causes include:¹

• Using a needle that is too small
• Pulling back too forcefully on a syringe
• Shaking tubes vigorously instead of gently inverting them
• Collecting blood through an IV catheter without proper technique
• Forcing blood into collection tubes

How to prevent it: Use the appropriate needle size, allow evacuated tubes to fill naturally, gently invert tubes according to manufacturer recommendations, and avoid excessive suction or force during collection.

2. Clotted Specimens²

Clotted specimens are one of the most common reasons anticoagulated tubes are rejected. Even small clots can interfere with hematology and coagulation testing.

Common causes include:

• Delayed mixing of anticoagulant tubes
• Insufficient inversion after collection
• Underfilling tubes containing anticoagulants

How to prevent it: Immediately invert anticoagulant tubes the recommended number of times after collection and ensure each tube fills to the proper volume.

3. Incorrect Fill Volume²

Many laboratory tubes are designed with a specific blood-to-additive ratio. Filling a tube too little or too much can produce inaccurate results.

This is especially important for:

• Sodium citrate (light blue) coagulation tubes
• Pediatric collection tubes
• Blood culture bottles

How to prevent it: Allow vacuum tubes to fill completely whenever possible and verify the correct fill level before removing the tube from the holder.

4. Incorrect Tube Selection

Using the wrong collection tube means the specimen may contain an inappropriate additive, or no additive at all, for the requested test.

Examples include:

• Collecting coagulation studies in an EDTA tube instead of sodium citrate
• Drawing chemistry tests in a tube with an interfering additive
• Using serum when plasma is required

How to prevent it: Always verify test requirements before collection and follow the laboratory's collection guide or test directory.

5. Patient Identification Errors²

Proper patient identification is one of the most important responsibilities of every phlebotomist. Even a perfectly collected specimen may be rejected if identification requirements are not met.

Examples include:

• Missing patient identifiers
• Mislabeled specimens
• Labels applied to the wrong tube
• Tubes labeled away from the patient's bedside

How to prevent it: Confirm patient identity using at least two identifiers, label specimens immediately after collection in the presence of the patient, and follow your facility's identification policies.

6. Improper Storage or Transport²

Some laboratory specimens require specific temperature conditions or rapid transport to maintain stability.

Examples include:

• Delayed transport
• Failure to place specimens on ice when required
• Exposure to excessive heat
• Failure to protect light-sensitive specimens

How to prevent it: Know the handling requirements for specialty tests and transport specimens promptly using the correct storage conditions.

Why Specimen Quality Matters

A rejected specimen doesn't just create more work for the laboratory, it directly affects patient care. Repeat collections can delay treatment, increase healthcare costs, inconvenience patients, and reduce confidence in the healthcare experience. For patients with difficult veins, pediatric patients, or critically ill individuals, avoiding a redraw is especially important.

High-quality specimen collection begins long before the sample reaches the laboratory. By paying close attention to patient identification, collection technique, tube selection, mixing, and specimen handling, phlebotomists play a critical role in ensuring accurate laboratory results and improving patient outcomes.

Every properly collected specimen helps provide clinicians with reliable information they can trust, and helps patients receive the care they need without unnecessary delays.

 

References:

1. Clinical and Laboratory Standards Institute. (2017). Collection of diagnostic venous blood specimens (7th ed., CLSI Standard GP41). Clinical and Laboratory Standards Institute.
2. Lippi, G., Chance, J. J., Church, S., Dazzi, P., Fontana, R., Giavarina, D., Grankvist, K., Huisman, W., Kouri, T., Palicka, V., Plebani, M., Puro, V., Salvagno, G. L., Sandberg, S., Sikaris, K., Watson, I., Stankovic, A. K., & Simundic, A.-M. (2011). Preanalytical quality improvement: From dream to reality. Clinical Chemistry and Laboratory Medicine, 49(7). https://doi.org/10.1515/cclm.2011.600