Meconium Collection: Nothing More, Nothing Less

What you need to know about meconium collection.

by Michelle Lach, MSIMC

Meconium is the first stool of a newborn infant. It is produced in utero and consists of materials such as epithelial cells, bile, mucous, and more. In most newborns, meconium is generally passed in the first day or so of life, has no odor, and appears as a very dark, tar-like substance. This helps distinguish meconium from the next phase of passage called transitional stool. 

Transitional stool will start to have an odor and present with a more brown, green, or yellow color as the newborn starts digesting milk. When drug testing the meconium of a newborn, it is important to note this difference since only meconium is created during gestation and transitional stool is created after birth. Collection of any stool other than meconium for drug testing purposes may result in a rejected specimen.  

Unlike umbilical cord tissue, drugs are not distributed uniformly throughout the meconium specimen (see Figure 1). Because of this, the collection of the entire mass of meconium is highly encouraged to assure that there will be enough specimen to test, and that the maximum window of drug detection is achieved. It can take multiple passages of meconium before the newborn begins the transitional stool phase. 

We require a minimum of 3 grams of meconium to be able to properly run our tests, so collecting the entire passage of meconium from newborns that have been exposed to substances of abuse is highly critical since they tend to have lower birth weights and create less specimen in the first place. If there is not enough specimen to run the test, the results are reported out as QNS. Quantity Not Sufficient (QNS) is a result of not having a sufficient quantity (volume) of specimen to test for the panels ordered.