Meconium is the bile-stained contents of the fetal intestine. Its appearance in the amniotic fluid is the result of fetal defecation. The obstetric literature is fraught with controversy and unanswered questions regarding the significance of meconium in the amniotic fluid and the appropriate management protocols that should be followed when it is discovered. It is believed by some medical experts that the passage of meconium is triggered by fetal stress, such as hypoxia or asphyxia, and that the presence of meconium in the fluid may be considered an indicator of fetal distress. Others point out that the presence of meconium in the amniotic fluid also may be a result of gastrointestinal maturity. Normal preterm fetuses rarely pass meconium; meconium passage in term or postterm pregnancies is observed more frequently.
Thus, the presence of meconium in the amniotic fluid is only one factor to be considered along with many other variables and clinical markers that may help to explain the etiology and timing of irreversible brain damage. There simply are too many variables and unanswered questions concerning the time it takes for meconium to initiate pathologic placental changes and/or to cause damage to umbilical cord vessels for meconium to be a useful marker to time brain injury, other than to possibly note that meconium exposure was either acute or chronic.
If the patient's medical records reveal that meconium was present in the amniotic fluid, parents may reasonably consider that :
- fetuses with meconium-stained amniotic fluid are at risk for meconium aspiration syndrome after birth;
- meconium can be a clinical marker for fetal distress or hypoxia, which can lead to, or be a sign of asphyxia;
- meconium increases the risk for infection; and
- postdated infants often pass meconium.
Most physicians will agree that the risk of adverse neonatal outcome increases when meconium is present in the amniotic fluid. However, experts continue to debate whether the risk of harm is associated with the meconium itself, or whether the overall risk is increased because of the underlying condition leading to the passage of meconium.
In cases involving postdated pregnancies, it should be determined if antepartum testing was initiated and repeated at appropriate intervals. The presence of thick meconium can be particularly ominous when it occurs in postterm pregnancies. In postterm pregnancies, cord compression is common, placental insufficiency may affect the delivery of oxygen and nutrients to the fetus, amniotic fluid decreases, and oligohydramnios may develop, which can lead to the passage of thick meconium.
It is reasonable to assume that the passage of meconium, in the presence of a nonreassuring, or a particularly ominous FHR pattern, is a sign of fetal distress. Some experts will say that, even if meconium is present in the amniotic fluid, clinicians may allow patients to labor in the presence of a reassuring FHR. However, even in the presence of a normal reassuring FHR pattern, in postdated pregnancies or in pregnancies with suspected growth restricted fetuses, it is a reasonable assumption that the passage of meconium is a sign of fetal distress.
In any case, it is important to ascertain whether any steps were taken to assess fetal scalp pH and to closely monitor the FHR for changes suggesting hypoxia and fetal distress. Late passage of meconium in a depressed term newborn can be another clinical marker of birth asphyxia. Parents should also question whether the clinician considered that the meconium may have been a precursor to progressive hypoxia and developing acidosis, or to other complications, such as meconium aspiration syndrome and its newborn sequella of persistent fetal circulation and pulmonary hypertension.
This web site is not intended as legal advice on cerebral palsy, and is not a substitute for obtaining guidance from your own legal counsel about cerebral palsy litigation. It provides general educational information about the standards of care and causation issues that can arise in obstetrical malpractice and cerebral palsy litigation. Readers of the articles contained within this web site should not act upon the cerebral palsy information without first consulting with a lawyer who is experienced in evaluating and litigating cerebral palsy and obstetrical malpractice cases. Mr. Apfel is admitted to practice law in Maryland and the District of Columbia. When Mr. Apfel is asked to participate in cerebral palsy
litigation filed in other states, he will associate with, and act as co-counsel with, an attorney licensed in that state who is familiar with the local laws and procedures.