Twins

Different types of twins

 

  1. Dichorionic diamniotic (DCDA) twins:

DCDA twins have 2 placentas and 2 separate sacs. These babies usually have different genetic material and only 10% will be identical.

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  1. Monochorionic diamniotic (MCDA) twins:

MCDA twins have a single placenta and 2 separate sacs. These babies have identical genetic material.

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  1. Monochorionic monoamniotic (MCMA) twins:

MCMA twins have a single placenta and both babies are moving around within the same sac. They also have the same genetic material.

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Some special problems twins may encounter during pregnancy

 

All twins:

• Premature delivery. The mean gestational age of delivery for twins is 37 weeks and for triplets is 32 weeks and for quadruplets is 29 weeks. 50% of all twin pregnancies will deliver prior to 36 weeks. Ultrasound can be used to monitor cervical length which is much more accurate than pelvic clinical examination. Cervical length can identify those patients at high risk of premature delivery.
• Growth restriction of one or both fetuses.
• Low birth weight less than 2500g. These infants are at significant risk of short-term and long-term handicaps.
• Greater risk for chromosomal and structural abnormalities.
• Greater risk of fetal loss.

Monochorionic diamniotic twins:

• Twin-Twin Transfusion Syndrome.
• Acute twin-twin transfusion.
• Twin-reversed arterial perfusion syndrome or Arcardic twin.

Monochorionic monoamniotic twins:

• Cord entanglement and loss of one or both fetuses.
• Acute twin-twin transfusion.
• Conjoined twins

Ultrasound scanning in twin pregnancies

Dichorionic diamniotic twins are usually routinely scanned monthly to assess growth and well being of each baby and for cervical assessment.

Monochorionic diamniotic twins are routinely scanned every 2 weeks from 18-34 weeks to monitor for the early signs of twin-twin transfusion syndrome.

Monoamniotic twins are scanned weekly after 24 weeks until elective delivery usually at 32 weeks in a hospital with good a neonatal intensive care unit.

Your doctor will decide how often he/she wants your pregnancy monitored with ultrasound. If there is a problem identified in the fetus or with the growth further investigations may be discussed with you including prenatal testing such as amniocnetesis or CVS.
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