Policy on Toxicology Sample Collection in Suspected Toxic Exposure
Toxicology samples should be collected when patients present with clinical signs of substance use (fluctuating consciousness, physiologic instability, severe intoxication, or amnesia) or when drug involvement is suspected by the patient, accompanying persons, or witnesses. 1
Indications for Collection
Collect toxicology samples in the following scenarios:
- Altered mental status including fluctuating level of consciousness 1
- Physiologic instability suggesting intoxication 1
- Severe intoxication with clinical impairment 1
- Amnesia regarding the event or exposure 1
- Suspicion raised by patient, family, or witnesses of possible drug involvement 1
Timing and Specimen Selection
Critical timing considerations:
- Collect samples within the first 24 hours whenever possible, as many substances have extremely short detection windows 1
- Obtain the first urine produced after suspected exposure, particularly for drug-facilitated scenarios, as this provides the highest yield 1
- Collect blood and urine in parallel when feasible, as each matrix provides complementary diagnostic information 2
Common pitfall: Many date rape drugs and substances of abuse are only detectable for 12-24 hours (GHB detectable in urine for only ~12 hours, flunitrazepam for 24-48 hours, ketamine for 24-72 hours), making delayed collection essentially worthless for detection. 3
Informed Consent Requirements
Obtain informed consent before collection when the patient has capacity, addressing: 1
- Confidentiality and discoverability of results in legal proceedings 1
- Value of results for immediate medical care 1
- Timing limitations affecting result interpretation 1
- Limitations of toxicology testing (cannot identify all drugs) 1
- Financial responsibility for testing 1
When patients are intoxicated or altered, confirmation of consent and event details should be reviewed later when cognition improves. 1
Collection Technique to Prevent Contamination
For external contamination prevention:
- Disinfect puncture sites with alcohol-based chlorhexidine or iodine solutions 1
- Use aqueous chlorhexidine if toxicological testing requirements preclude alcohol-based solutions 1
- Use separate sterile instruments for each sample to avoid cross-contamination 1
For blood collection:
- Prioritize subclavian vein for peripheral blood over jugular or femoral sites 1
- Collect cardiac blood only when peripheral access is unavailable 1
Chain of Custody Documentation
Document complete chain of custody if specimens may be used in legal proceedings, coordinating collection and transport with sexual assault response teams, healthcare providers, and law enforcement as appropriate. 1, 3
Special Testing Considerations
Standard drug screening panels do NOT include:
- Flunitrazepam (not detected by routine benzodiazepine screens) 1, 3
- GHB 3
- Ketamine 3
- Many over-the-counter antihistamines 1, 3
- Trazodone 4
- Most "date rape drugs" 1, 3
You must specifically request testing for suspected substances that fall outside routine panels, consulting with toxicology laboratories, Poison Control Centers, or forensic laboratories for proper specimen collection and interpretation. 1, 3
For heavy metal exposure: Send both blood (for acute exposure and current body burden) and urine specimens, as each provides distinct diagnostic information. 2
Critical Clinical Context
Do not delay sample collection to complete history and physical examination when drug-facilitated exposure is suspected—many substances become undetectable within hours. 1 The American Academy of Pediatrics emphasizes that toxicology screening should be performed as soon as possible, potentially even before finishing the clinical evaluation. 1
Voluntary substance use does not negate the need for standard care or affect the legal status of non-consensual events. 1 Alcohol is the most common substance detected (41.1% of cases), while classic "date rape drugs" like flunitrazepam and GHB account for less than 2% of cases. 1, 3