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=Monozygotic versus dizygotic twins= | =Monozygotic versus dizygotic twins= | ||
==Monoamniotic-monochorionic | ==Monoamniotic-monochorionic gestation== | ||
*Abbreviated ''MoMo''. | |||
===General=== | |||
*Split at approximately 7th day. | |||
*Always monozygotic twins. | |||
*Very rare. | |||
*High rate of complications - cords get into knots. | |||
===Gross=== | |||
*No membrane between the fetuses - apparently clinically. | *No membrane between the fetuses - apparently clinically. | ||
* | *Umbilical cord attachments usually very close to one another.<ref name=Ref_Placenta133>{{Ref Placenta|133}}</ref> | ||
==Diamniotic-monochorionic | ==Diamniotic-monochorionic gestation== | ||
*Abbreviated ''DiMo''. | |||
===General=== | ===General=== | ||
* | *The dogma is that the twins are always monozygotic. | ||
**There is a case report of an exception.<ref name=pmid12853583>{{Cite journal | last1 = Redline | first1 = RW. | title = Nonidentical twins with a single placenta--disproving dogma in perinatal pathology. | journal = N Engl J Med | volume = 349 | issue = 2 | pages = 111-4 | month = Jul | year = 2003 | doi = 10.1056/NEJMp030097 | PMID = 12853583 }}</ref> | |||
*Highest risk of TTTS ([[twin-to-twin transfusion syndrome]]). | *Highest risk of TTTS ([[twin-to-twin transfusion syndrome]]). | ||
===Gross=== | ===Gross=== | ||
Features - T-zone membrane is:<ref name=Ref_Placenta128>{{Ref Placenta|128}}</ref> | |||
*Thin. | |||
*Translucent. | |||
*No blood vessel remnants. | |||
===Microscopic=== | ===Microscopic=== | ||
Features: | Features:<ref>URL: [http://library.med.utah.edu/WebPath/PLACHTML/PLAC006.html http://library.med.utah.edu/WebPath/PLACHTML/PLAC006.html]. Accessed on: 30 October 2013.</ref> | ||
*No | *No chorion in the T-zone - '''key feature'''. | ||
====Images==== | |||
<gallery> | |||
Image:Monochorionic Diamniotic Twins, Intervening Membrane.jpg | Di-Mo placenta. (WC/euthman) | |||
</gallery> | |||
*[http://www.pathologypics.com/PictView.aspx?ID=1304 Diamniotic-monochorionic gestation (pathologypics.com)]. | |||
*[http://library.med.utah.edu/WebPath/PLACHTML/PLAC006.html Di-Mo placenta (utah.edu)]. | |||
===Sign out=== | |||
<pre> | |||
TWIN PLACENTA, UMBILICAL CORDS AND FETAL MEMBRANES, BIRTH: | |||
- FETAL MEMBRANES AT T-ZONE: | |||
-- CHORION ABSENT (DIAMNIOTIC-MONOCHORIONIC GESTATION). | |||
- TWIN A: | |||
-- THREE VESSEL UMBILICAL CORD WITHIN NORMAL LIMITS. | |||
-- FETAL MEMBRANES WITHIN NORMAL LIMITS. | |||
-- PLACENTAL DISC WITH THIRD TRIMESTER VILLI WITHIN NORMAL LIMITS. | |||
- TWIN B: | |||
-- THREE VESSEL UMBILICAL CORD WITHIN NORMAL LIMITS. | |||
-- FETAL MEMBRANES WITHIN NORMAL LIMITS. | |||
-- PLACENTAL DISC WITH THIRD TRIMESTER VILLI WITHIN NORMAL LIMITS. | |||
</pre> | |||
==Diamniotic-dichorionic | ==Diamniotic-dichorionic gestation== | ||
*Abbreviated ''DiDi''. | |||
===General=== | ===General=== | ||
*Most dizygotic (70%), may be monozygotic (30%). | *Most dizygotic (70%), may be monozygotic (30%). | ||
Line 25: | Line 60: | ||
===Gross=== | ===Gross=== | ||
*Thick | Features - T-zone:<ref name=Ref_Placenta129>{{Ref Placenta|129}}</ref> | ||
*Thick. | |||
*Less translucent. | |||
*Blood vessels - fine branching. | |||
===Microscopic=== | ===Microscopic=== | ||
Features: | Features: | ||
* | *Chorion present in the T-zone. | ||
====Images==== | |||
<gallery> | |||
Image:Diamniotic-dichorionic_twin_placenta_-_low_mag.jpg | DiDi placenta. (WC) | |||
Image:Diamniotic dichorionic placenta, HE 1.jpg | DiDi placenta. (WC/euthman) | |||
Image:Diamniotic dichorionic placenta, HE 2.jpg | DiDi placenta. (WC/euthman) | |||
</gallery> | |||
*[http://library.med.utah.edu/WebPath/PLACHTML/PLAC005.html DiDi placenta (utah.edu)]. | |||
===Sign out=== | |||
====Normal==== | |||
<pre> | |||
TWIN PLACENTA, UMBILICAL CORDS AND FETAL MEMBRANES, BIRTH: | |||
- FETAL MEMBRANES AT T-ZONE: | |||
-- CHORION PRESENT (DIAMNIOTIC-DICHORIONIC GESTATION). | |||
- TWIN A: | |||
-- THREE VESSEL UMBILICAL CORD WITHIN NORMAL LIMITS. | |||
-- FETAL MEMBRANES WITHIN NORMAL LIMITS. | |||
-- PLACENTAL DISC WITH THIRD TRIMESTER VILLI WITHIN NORMAL LIMITS. | |||
- TWIN B: | |||
-- THREE VESSEL UMBILICAL CORD WITHIN NORMAL LIMITS. | |||
-- FETAL MEMBRANES WITHIN NORMAL LIMITS. | |||
-- PLACENTAL DISC WITH THIRD TRIMESTER VILLI WITHIN NORMAL LIMITS. | |||
</pre> | |||
====Early delivery==== | |||
<pre> | |||
TWIN PLACENTA, UMBILICAL CORDS AND FETAL MEMBRANES, CESAREAN SECTION: | |||
- FETAL MEMBRANES AT T-ZONE: | |||
-- CHORION PRESENT (DIAMNIOTIC-DICHORIONIC GESTATION). | |||
- TWIN A: | |||
-- THREE VESSEL UMBILICAL CORD WITHIN NORMAL LIMITS. | |||
-- FETAL MEMBRANES WITHIN NORMAL LIMITS. | |||
-- PLACENTAL DISC WITH FOCALLY MILDLY LARGE THIRD TRIMESTER VILLI AND | |||
ZONAL CONGESTION. | |||
- TWIN B: | |||
-- THREE VESSEL UMBILICAL CORD WITHIN NORMAL LIMITS. | |||
-- FETAL MEMBRANES WITHIN NORMAL LIMITS. | |||
-- PLACENTAL DISC WITH FOCALLY MILDLY LARGE THIRD TRIMESTER VILLI. | |||
</pre> | |||
=Pathology seen only in twin pregnancies= | =Pathology seen only in twin pregnancies= | ||
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**Placental disc: large, pale. | **Placental disc: large, pale. | ||
*Recipient: | *Recipient: | ||
**Twin: hypervolemia, polyuria, polyhydramnios, +/- [[hydrops fetalis]], +/- CHF, hemolytic janundice, +/- large congested organs. | **Twin: hypervolemia, polyuria, [[polyhydramnios]], +/- [[hydrops fetalis]], +/- CHF, hemolytic janundice, +/- large congested organs. | ||
**Placental disc: small, firm, congested. | **Placental disc: small, firm, congested. | ||
===Gross=== | ===Gross=== | ||
*Large vessels that connect the two umbilical cords. | *Large vessels that connect the two umbilical cords. | ||
Image: | |||
<gallery> | |||
Image:De Wikkellkinderen.jpeg | Painting thought to depict TTTS. (WC) | |||
</gallery> | |||
===Microscopic=== | ===Microscopic=== |
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