Susan Horton had been a stay-at-home mom for almost 20 years, and now—pregnant with her fifth child—she felt a hard-won confidence in herself as a mother.
Then she ate a salad from Costco.
Horton didn’t realize that she would be drug-tested before her child’s birth. Or that the poppy seeds in her salad could trigger a positive result on a urine drug screen, the quick test that hospitals often use to check pregnant patients for illicit drugs. Many common foods and medications—from antacids to blood pressure and cold medicines—can prompt erroneous results.
If Horton had been tested under different circumstances—for example, if she was a government employee and required to be tested as part of her job—she would have been entitled to a more advanced test and to a review from a specially trained doctor to confirm the initial result.
I wasn’t presenting Mythbusters as rigorous science, simply pointing out that a false positive is possible when using the tests as directed. If you want hard science, just go to Mayo Clinic’s practical guide for clinicians:
https://www.mayoclinicproceedings.org/article/S0025-6196(11)61120-8/fulltext
Opiate screening cutoff levels for DHHS were changed from 300 ng/mL to 2000 ng/mL of morphine in December 1998 to avoid false-positive results from poppy-seed ingestion. However, the sensitivity for detecting true opiate use can be a concern,112 and most clinical laboratories continue to use the lower cutoff.53 Positive results for heroin abuse are caused by use of prescribed opiates, such as codeine and hydrocodone; however, ingestion of modest amounts of poppy seeds has been known to cause a positive result from urinalysis. Ingestion of poppy-seed cookies (containing about 1 teaspoon of poppy-seed filling available commercially in the United States for baking) produced positive results for opiates within 2 hours of ingestion among 5 patients.62 Codeine was also found in a concentration of 20 ng/mL in 2 samples 2 hours after ingestion. Urine samples analyzed after 24 hours were negative for opiates. Similar results were seen in another analysis in which consumption of poppy-seed bagels produced positive results for codeine and morphine up to 25 hours after ingestion.60 A single bagel was estimated to contain 1.5 mg of morphine and 0.1 mg of codeine. Similar results were observed in other analyses with slight variations ranging from 1 hour for earliest detection of morphine to 60 hours for the latest detection.20
They have citations with links. I’m not going to copy them all here.
Yes. What that says is that it is possible to false-positive. Particularly if the test is overly sensitive
As for the number of patients who did false positive: I might be having one of those days but I can’t find the study size for those. It looks like they are only in referenced papers that I don’t have access to because of a different problem in society.
Which gets back to what I have been saying all alone: Yes, it is possible. No, it is not particularly probable. But considering the consequences of a false positive, almost all guidance is going to say to err on the side of caution.
And, to reiterate, it is insane that social services would step in immediately rather than waiting for a blood test from someone who is already confined to a hospital because… pregnancy.
