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The term meconium derives from ancient Greek meconium-arion, or "opium-like." Aristotle developed the term because he believed that it induced foetal sleep. The contents of the foetal intestine, meconium is a sterile admixture of numerous chemicals, including mucous glycoprotiens, swallowed vernix caseosa , gastrointestinal secretions, bile, pancreatic and liver enzymes, plasma proteins, minerals, and lipids. Mucopolysaccharides compose 80% of meconium's dry weight. The concentration of pancreatic and liver enzymes vary with gestational age.
Meconium Aspiration Syndrome
Meconium Aspiration Syndrome (MAS) is a common
problem faced by paediatricians and obstetricians. In the U.S., there
are an estimated 520,000 births (12% of live births) complicated by meconium
stained amniotic fluid (MSAF). Of these, 35% will develop MAS (approximately
4% of all live births). 30% of babies with MAS will require mechanical
ventilation, 10% develop pneumothoraces, and 4% die. As many as 66% of
all cases of persistent pulmonary
hypertension (PPHN) are related to meconium aspiration syndrome.
Meconium aspiration syndrome should be suspected in any neonate with
a history of meconium-stained amniotic fluid and respiratory
distress . MAS is most strictly defined as the presence of any
meconium below the vocal cords.
Risk factors have been developed to predict which babies will develop MAS. These include maternal admission of labour induction with nonreassuring foetal heart tracings, need for suctioning of the baby's trachea, one-minute Apgar score of 4 or less, and caesarean-section delivery. The presence of at least one of these risk factors had a positive predictive value of 8% and a negative predictive value of 99%.
The syndrome of meconium aspiration can be identified by its clinical hallmarks: history of meconium aspiration and hypoxemia without structural heart disease. To the right is a flow diagram describing this syndrome's pathophysiology, compiled from currently available literature:Treatment
Therapy begins in the delivery room, aimed at preventing the neonate who has been exposed to MSAF from aspirating that fluid.
Amnioinfusion : This involves infusing
normal saline into the amniotic space, which dilutes the meconium and/or
decompresses the umbilical cord and the placenta. May ameliorate respiratory
distress, acidosis, and the incidence of meconium aspiration syndrome
or it may increase incidence of foetal heart rate abnormalities and increased
incidence of Caesarean
deliveries and operative vaginal deliveries.
For further, more detailed information on this topic, please refer to the reference source for this page.
The information in this page is presented in summarised form and has been taken
from the following source(s):
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