Difference between revisions of "Placenta"

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=Twin placentas=
=Twin placentas=
{{Main|Twins placentas}}
These are often submitted... even if they are normal.  In these specimens, usually, the chorion is the key.
These are often submitted... even if they are normal.  In these specimens, usually, the chorion is the key.


==General==
It covers:
No membrane between fetuses.
*Monozygotic vs. dizygotic twins.
*Split at approx. 7th day.
*Twin-to-twin transfusion syndrome.
 
===Diamnionic-monochorionic (DiMo)===
*No interposed chorion.<ref name=Ref_H4P2_979>{{Ref H4P2|979}}</ref>
*Always monozygotic.
*Highest risk of TTTS (twin-to-twin transfusion syndrome).
 
===Diamnionic-dichorionic (DiDi)===
*Most dizygotic (70%), may be monozygotic (30%).
*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=
Retrieved from "https://librepathology.org/wiki/Placenta"