CASE 5: Problems of the Placenta

History:

These male infants are the product of a 37 week gestation in a 35-year-old mother whose only previous pregnancy had terminated in a spontaneous abortion at 18 weeks. The babies weighed 2600 and 2400 grams respectively for the firstborn and secondborn babies. Apgar scores were 8 at 1 minute and 9 at five minutes for the first baby, and 5 at 1 minute and 9 at five minutes for the second baby, who was noted to have a nuchal cord and appeared covered with meconium. The placenta weighed 900 gm.

Image 5.1:

A twin placenta is shown here.

Image 5.2:

A singleton placenta is shown for comparison with greenish staining.

Image 5.3:

The dividing membranes of the twin placenta in this case are shown here. How would you describe it? Are these monozygous or dizygous twins? How could you prove their zygosity?

This is a diamnionic-dichorionic twin placenta. Zygosity can be suggested, but not proven, from the following statistics:

Zygosity could be proven only by HLA typing, DNA studies, red cell enzymes, or extended blood typing.

Image 5.4:

The umbilical cord of the first twin is shown here. What do you notice?

There is only a single umbilical artery.

Questions:

1. Are these twins small, appropriate, or large for gestational age?

They are appropriate for gestational age.

2. Is there a twin-twin transfusion syndrome in this case?

No. First, the size differential is not great enough, and second, they are probably not monozygous twins.

3. What is the significance of the meconium staining?

Meconium may be released from the fetal rectum in utero under conditions of fetal distress. Evidence for this comes from the greenish staining of placenta and/or fetus. The real risk to the infant is the possibility of a meconium aspiration.

4. What is the significance of the two vessel cord?

A two vessel cord (single artery and single vein) is seen in about 1% of births. It suggests a greater likelihood for other anomalies to be present.