Difference between revisions of "Twin placentas"
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'''Twin [[placenta]]s''' often come to the pathologist... even if they are normal. In these specimens, usually, the chorion is the key; the pathologist may be able to sort-out whether the twins are monozygotic (identical) or dizygotic (fraternal). | '''Twin [[placenta]]s''' often come to the pathologist... even if they are normal. In these specimens, usually, the chorion is the key; the pathologist may be able to sort-out whether the twins are monozygotic (identical) or dizygotic (fraternal). | ||
=Monozygotic versus dizygotic twins= | |||
==Monoamniotic-monochorionic (MoMo)== | |||
*No membrane between the fetuses. | *No membrane between the fetuses - apparently clinically. | ||
*Split at approximately 7th day. | *Split at approximately 7th day. | ||
*Monozygotic twins. | *Monozygotic twins. | ||
==Diamniotic-monochorionic (DiMo)== | |||
===General=== | |||
*Always monozygotic. | |||
*Highest risk of TTTS ([[twin-to-twin transfusion syndrome]]). | |||
===Gross=== | |||
*Thin membrane at T-zone. | |||
===Microscopic=== | |||
Features: | |||
*No interposed chorion.<ref name=Ref_H4P2_979>{{Ref H4P2|979}}</ref> | *No interposed chorion.<ref name=Ref_H4P2_979>{{Ref H4P2|979}}</ref> | ||
==Diamniotic-dichorionic (DiDi)== | |||
===General=== | |||
*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. | ||
===Gross=== | |||
*Thick membrane at T-zone. | |||
===Microscopic=== | |||
Features: | |||
*Interposed chorion.<ref name=Ref_H4P2_979>{{Ref H4P2|979}}</ref> | |||
=Pathology seen only in twin pregnancies= | |||
==Twin-to-twin transfusion syndrome== | ==Twin-to-twin transfusion syndrome== | ||
===General=== | ===General=== | ||
Revision as of 19:13, 9 January 2013
Twin placentas often come to the pathologist... even if they are normal. In these specimens, usually, the chorion is the key; the pathologist may be able to sort-out whether the twins are monozygotic (identical) or dizygotic (fraternal).
Monozygotic versus dizygotic twins
Monoamniotic-monochorionic (MoMo)
- No membrane between the fetuses - apparently clinically.
- Split at approximately 7th day.
- Monozygotic twins.
Diamniotic-monochorionic (DiMo)
General
- Always monozygotic.
- Highest risk of TTTS (twin-to-twin transfusion syndrome).
Gross
- Thin membrane at T-zone.
Microscopic
Features:
- No interposed chorion.[1]
Diamniotic-dichorionic (DiDi)
General
- Most dizygotic (70%), may be monozygotic (30%).
- If monozygotic -- split before 3 days.
Gross
- Thick membrane at T-zone.
Microscopic
Features:
- Interposed chorion.[1]
Pathology seen only in twin pregnancies
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).[2]
Prevalence:
- Seen in ~15% of monozygotic twins.[2]
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:[3]
- 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.
See also
References
- ↑ 1.0 1.1 Sternberg, Stephen S. (1997). Histology for Pathologists (2nd ed.). Lippincott Williams & Wilkins. pp. 979. ISBN 978-0397517183.
- ↑ 2.0 2.1 Humphrey, Peter A; Dehner, Louis P; Pfeifer, John D (2008). The Washington Manual of Surgical Pathology (1st ed.). Lippincott Williams & Wilkins. pp. 469. ISBN 978-0781765275.
- ↑ Humphrey, Peter A; Dehner, Louis P; Pfeifer, John D (2008). The Washington Manual of Surgical Pathology (1st ed.). Lippincott Williams & Wilkins. pp. 469-70. ISBN 978-0781765275.