A new born's stool, also known Meconium, contains the amniotic fluid swallowed by the infant, hair, epithelial cells and other contents of the body. It is often dark-green or blackish in color and can be quite viscous in consistency. It is also completely sterile because the infant has not had time to come in contact with any micro-organisms during its formation.
Meconium is quite often used to test for any exposure the infant might have had to drug and alcohol. The reason why this testing is done in the first place is because self-reporting of ingestion illicit substances during pregnancy is notoriously unreliable.
Meconium is also excellent for the testing of these substances because it will detect any drugs that were ingested during the last 3-4 months of the pregnancy. The blood from the umbilical cord and infant urine can also be tested for illicit substance usage but they will only reveal the presence of drugs that were taken in a much small time frame.
The drug tests suing Meconium were found to be quite sensitive. One study found the sensitivity to be 87% for cocaine and 77% for opiate detection but much lower for cannabinoid drugs (20-27%). This high sensitivity combined with the relative ease with which the sample can be collected make meconium testing as the ideal choice when it comes to screen infants for the presence of drugs.
Every drug test comes with the possibility of some in-built error and the same is true for Meconium testing. Some amount of false positive results have been returned for users that took drugs for the first time before pregnancy but the drug did not have adequate time for deposition before pregnancy.
Labs require a sample of about three grams for accurate testing of Meconium. The diaper with the first stool passed by the child is usually more than enough to provide an adequate sample to the laboratory.
The issue of testing Meconium for drug testing can, however, run into some social prejudices with minorities and certain ethnicities being targeted more than others. The official rules allow for healthcare facilities to make their own guidelines about choosing subjected to test allowing for a great deal of flexibility and the hope that common sense prevails most often.
Children of women that have a history of previous drug usage, drug addiction, sexually transmitted diseases or admit to having used drugs and alcohol during pregnancy are the obvious candidates for drug testing new born stool.
Other clinical situations where meconium drug testing may be carried out include babies born to mothers had very little or no prenatal care/education, babies that are displaying unexplained neurological symptoms, babies born to mothers where there was an unexpected and unexplained placental disruption, babies that show growth retardation without any obvious cause and those babies that exhibit symptoms of drug withdrawal.
Meconium testing for drugs was first developed in the 1970’s and has been fine tuned greatly since then. The results from these drug tests are considered to be the most accurate representation of long term toxic exposure the child may have suffered from.
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