P2A005: Negative UDS Leading to Cognitive Bias and Ultimately the Death of a Toddler: A Case Report

Introduction: Urine drug screens (UDS) gained popularity in the 1980’s as an employment screening tool and use
quickly spread to clinical medicine as a diagnostic tool. Most initial screens are immunoassays using
antibodies to identify the presence of drugs in a patient sample. Frequently used standard immunoassay
screens look for recreational drugs such as amphetamines, barbiturates, benzodiazepines, cocaine,
opiates, and THC. The results of these UDSs are dependent on when the sample was collected, how
much drug is in the sample, the drug’s chemical structure, and what is specifically being tested for by the
screen ordered.

Case Description: This case involves a 3-year-old who, despite two admissions for naloxone-responsive apnea, died of
acute fentanyl toxicity. On two separate occasions over two months, he presented to the Emergency
Department (ED) apneic and unresponsive. Both times he was treated successfully with naloxone and
admitted. During the first hospitalization, a UDS, lumbar puncture, and brain MRI were unremarkable.
An electroencephalogram revealed generalized delta slowing with intermittent sharp activity, deemed
“possibly related to seizures”. Social services was notified, and the patient was discharged home with his
parents. Given the recurrence of symptoms prompting his second hospitalization and a second negative
UDS at that time, levetiracetam was initiated for presumed seizures. A send-out serum fentanyl test was
ordered by the ED provider who recognized the parents had recently been arrested for fentanyl
possession with intent to distribute. Despite a second social services referral and pending fentanyl test,
he was again discharged home with his parents. Ten days after discharge the fentanyl test came back
positive. Social services was notified, but no intervention occurred. Four days later, the patient was seen
by neurology and levetiracetam continued. Five days later, he was found unresponsive, was in asystole,
and died. Postmortem serum fentanyl concentration was 14 ng/ml.

Discussion: While suspicion for synthetic opioid exposure was documented, the negative UDSs were included in the
rationale that a seizure disorder was the most likely etiology of this patient’s symptoms. In this case, the
initial UDSs used tested for opiates. The distinct fentanyl structure prevents interaction with antibodies
used in UDS opiate tests, which react with natural opiates like morphine, not synthetic opioids like
fentanyl or its analogs.
There were several aspects of this case that led to the failure to protect the child in question, most
hinging on a misinterpretation of the initial UDS results. Better education on the nuances and limitations
of drug testing is crucial for all charged with protecting children, especially in this time of increasingly
prevalent synthetic drug use.

Conclusion: This case serves as a critical reminder that we must improve education and understanding of the
nuances and limitations of drug testing.