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Difference between revisions of "Placenta"
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→Twin placentas: +TTTS
(+overview) |
(→Twin placentas: +TTTS) |
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*Most dizygotic (70%), may be monozygotic (30%). | *Most dizygotic (70%), may be monozygotic (30%). | ||
*If monozygotic -- split before 3 days. | *If monozygotic -- split before 3 days. | ||
==Twin-to-twin transfusion syndrome== | |||
===General=== | |||
*Abbreviated as TTTS. | |||
Definition: | |||
*Monozygotic twins that share a placental disc, have vessels which cross-over between the twins that lead to a blood imbalance between the two twins. | |||
**Only seen in monozygotic twins. | |||
**Vascular connection may be vein-to-vein, artery-to-vein, artery-to-artery (uncommon).<ref name=Ref_WMSP469>{{Ref WMSP|469}}</ref> | |||
Prevalence: | |||
*Seen in ~15% of monozygotic twins.<ref name=Ref_WMSP469>{{Ref WMSP|469}}</ref> | |||
Clinical: | |||
*Donor: | |||
**Twin: hypovolemic, oliguric, oligohydramnic, +/- anemia, +/-hypoglycemia, +/- small pale organs. | |||
**Placental disc: large, pale. | |||
*Recipient: | |||
**Twin: hypervolemia, polyuria, polyhydramnios, +/- hydrops fetalis, +/- CHF, hemolytic janundice, +/- large congested organs. | |||
**Placental disc: small, firm, congested. | |||
===Gross=== | |||
*Large vessels that connect the two umbilical cords. | |||
===Microscopic=== | |||
Features:<ref name=Ref_WMSP469-70>{{Ref WMSP|469-70}}</ref> | |||
*Artery-to-vein anatomosis - where artery and vein are associated with different umbilical cords. | |||
*Donor twin side of placenta: | |||
**Edematous villi. | |||
**Increased nucleated RBCs. | |||
*Recipient twin side of placenta: | |||
**Congested. | |||
=Diseases of the placental attachment= | =Diseases of the placental attachment= | ||