Meconium in amniotic fluid Meconium is normally retained in the infant's bowel until after birth, but sometimes it is expelled into the
amniotic fluid prior to birth or during
labor and delivery. The stained amniotic fluid is recognized by medical staff as a possible sign of
fetal distress. Some
post-dates pregnancies (when they are more than 40 weeks pregnant) may also have meconium-stained amniotic fluid without fetal distress. Medical staff may aspirate the meconium from the nose and mouth of a newborn immediately after delivery in the event the baby shows signs of respiratory distress to decrease the risk of
meconium aspiration syndrome, which can occur in meconium-stained amniotic fluid. Most of the time that the amniotic fluid is stained with meconium, it will be homogeneously distributed throughout the fluid, making it brown. This indicates that the fetus passed the meconium some time ago such that sufficient mixing occurred as to establish the homogeneous mixture. Terminal meconium occurs when the fetus passes the meconium a short enough time before birth/cesarean section that the amniotic fluid remains clear, but individual clumps of meconium are in the fluid.
Failure to pass meconium The failure to pass meconium is a symptom of several diseases including
Hirschsprung's disease and
cystic fibrosis. The meconium sometimes becomes thickened and congested in the
intestines, a condition known as
meconium ileus. Meconium ileus is often the first sign of
cystic fibrosis. In cystic fibrosis, the meconium can form a bituminous black-green mechanical obstruction in a segment of the ileum. Beyond this, there may be a few separate grey-white globular pellets. Below this level, the bowel is a narrow and empty micro-colon. Above the level of the obstruction, there are several loops of hypertrophied bowel distended with fluid. No meconium is passed, and abdominal distension and vomiting appear soon after birth. About 20% of cases of cystic fibrosis present with meconium ileus, while approximately 20% of one series of cases of meconium ileus did not have cystic fibrosis. The presence of meconium ileus is not related to the severity of the cystic fibrosis. The obstruction can be relieved in a number of ways. Meconium ileus should be distinguished from meconium plug syndrome, in which a tenacious mass of mucus prevents the meconium from passing and there is no risk of intestinal perforation. Meconium ileus has a significant risk of intestinal perforation. In a barium enema, meconium plug syndrome shows a normal or dilated colon as compared to micro-colon in meconium ileus.
Testing meconium for drugs Meconium can be tested for various drugs, to check for
in utero exposure. Using meconium, a Canadian research group showed that by measuring a by-product of
alcohol, fatty acid ethyl esters (FAEE), they could objectively detect excessive maternal alcohol consumption during pregnancy. In the US, the results of meconium testing may be used by
child protective services and other
law enforcement agencies if the capacity of the parents to look after their child is in question. Meconium can also be analyzed to detect the tobacco use of mothers during their pregnancy, which is commonly under-reported. == Sterility ==