![]() ![]() Overall rates are on a decline in recent years, as post-term pregnancies are reduced by induction at 41 weeks and advances have been made by early intervention with an abnormal fetal heart rate. Intrauterine growth restriction is also a risk factor for MSAF, as higher rates have been reported in such populations of neonates. Preterm births are not frequently associated with meconium and it is estimated that only 5% are complicated by MSAF. In post-term pregnancies it is much more common as studies show rates as high as 23–52% in pregnancies at 42 weeks and 27.1% in pregnancies at 41 weeks' gestation. It has a dark green colour, high viscosity and accumulates in the fetal intestinal tract during the 3rd trimester of pregnancy, being the first intestinal discharge released within 48 hours after birth.Īntenatal or intrapartum meconium release is referred to as meconium staining of amniotic fluid (MSAF) and it has been estimated to occur in approximately 13% of all live births with rates reported between 8 and 20%. Meconium is comprised of gastrointestinal secretions, bile, mucus, vernix caseosa, lanugo hair, cellular debris and amniotic fluid. Hence the presence of thick meconium needs increased vigilance with continuous electronic fetal monitoring and a lower threshold for action with CTG abnormalities. The incidence of abnormal fetal heart rate patterns, increased incidence of operative deliveries for impending fetal hypoxia, and poor neonatal outcomes is greater when there is thick meconium stained liquor. Meconium aspiration can happen in utero and this is precipitated by gasping of the fetus as a result of hypoxia. Aggressive tracheal toilet at delivery helps to reduce the load but will not significantly impact on cases with pre-existing in utero aspiration. hypoxia and metabolic acidosis) causes added damage to the lungs and therefore further complicates the management of MAS. Although fetuses do not normally draw amniotic fluid into the airway, they gasp when hypoxic and therefore the coexistence of hypoxia and acidosis may precipitate meconium aspiration. Meconium can be aspirated in utero or after birth. Passage of meconium in the preterm fetus should raise the possibility of intrauterine infection such as listeriosis. It can therefore be a marker of maturation of the central nervous system and the gastrointestinal system. #Amniotic fluid in toilet fullThe incidence of meconium staining of the liquor increases from 36 to 42 weeks gestation, reaching around 20–30% at full term. ![]() Fetal infection is also associated with the passage of meconium. ![]() PGs can increase the intestinal motility of the fetus and stimulate the fetus to pass meconium. Other reasons include the use of misoprostol, a prostaglandin (PG E1) given for induction of labour. One is a function of fetal maturity, but it may also indicate possible fetal compromise. There are few reasons why meconium is passed by the fetus in utero. ![]()
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