Difference between revisions of "Placenta"

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Placenta (view source)

Revision as of 18:23, 8 January 2011

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The '''placenta''' feeds the developing baby, breathes for it and disposes of its waste.
The '''placenta''' feeds the developing baby, breathes for it and disposes of its waste.


==Normal==
=Clinical=
Amnion - next to fetus, surrounds amniotic fluid, avascular.
==Examination of the placenta==
*Most placentas are ''not'' examined by a pathologist.
 
Indications for exam by a pathologist:
*Abnormalities in the:
*#Fetus:
*#*Bad fetal outcome.
*#*Suspected or known congenital abnormalities ''or'' chromosomal abnormalities.
*#Mother:
*#*Infection/suspected infection.
*#*Pre-term labour.
*#*Maternal disease (e.g. SLE, coagulopathy).
*#*Complicated pregnancy (preclampsia, pregnancy induced hypertension, gestational diabetes).
*#Placenta:
*#*Unusual gross characteristics.
 
==Bleeding in late pregnancy==
DDx of bleeding in late pregnancy:
*Placental abruption (most common).
*Placenta previa.
*Vasa previa (fetus losing blood).
 
==Clinical screening tests==
*PAPP-A - low values seen in aneuploidy.<ref>URL: [http://www.ncbi.nlm.nih.gov/sites/entrez?Db=gene&Cmd=ShowDetailView&TermToSearch=5069 http://www.ncbi.nlm.nih.gov/sites/entrez?Db=gene&Cmd=ShowDetailView&TermToSearch=5069]. Accessed on: 7 July 2010.</ref>
 
{{main|Pregnancy}}
 
=Normal histology=
==Amnion==
General:
*Next to fetus, surrounds amniotic fluid, avascular.
 
Characteristics:
*Characterized by a single layer of cells.<ref name=Ref_H4P2_974>{{Ref H4P2|974}}</ref>
*Characterized by a single layer of cells.<ref name=Ref_H4P2_974>{{Ref H4P2|974}}</ref>
**Cuboidal/squamoid shape.
**Cuboidal/squamoid shape.
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*'Fibroblastic layer'.<ref name=Ref_H4P2_974>{{Ref H4P2|974}}</ref>
*'Fibroblastic layer'.<ref name=Ref_H4P2_974>{{Ref H4P2|974}}</ref>


Chorion - surrounds amnion
==Chorion==
General:
*Surrounds amnion.
 
Characteristics:
*Layers:<ref name=Ref_H4P2_977>{{Ref H4P2|977}}</ref>
*Layers:<ref name=Ref_H4P2_977>{{Ref H4P2|977}}</ref>
**'Reticular layer' - cellular (inner aspect).
**'Reticular layer' - cellular (inner aspect).
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**Beneath of the "trophoblastic X cells" is ''decidua'' (mnemonic ''NEW'' = nucleus central, eosinophilic, well-defined cell border), which is maternal tissue.  
**Beneath of the "trophoblastic X cells" is ''decidua'' (mnemonic ''NEW'' = nucleus central, eosinophilic, well-defined cell border), which is maternal tissue.  


===Additional terms===
==Common terms==
*Chorionic plate - fetal aspect of placenta.
*Chorionic plate - fetal aspect of placenta.
*Basal plate - maternal aspect of placenta.
*Basal plate - maternal aspect of placenta.
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**Place to look for maternal vessels.
**Place to look for maternal vessels.


==Grossing==
=Grossing=
This is often very quick.  The gross is quite important, as some things cannot be diagnosed microscopically.
==General==
*Dimensions:
*Dimensions:
**Disc.  
**Disc.  
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**Maternal surface - are the cotyledons intact?
**Maternal surface - are the cotyledons intact?


===Sections===
==Sections==
*Cord two sections.
*Cord two sections.
*Cord at insertion.
*Cord at insertion.
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*Placenta - full thickness (maternal and fetal surface).
*Placenta - full thickness (maternal and fetal surface).


===Placental membranes===
==Placental membranes==
Appearance:<ref name=Ref_Lester461>{{Ref Lester|461}}</ref>
Appearance:<ref name=Ref_Lester461>{{Ref Lester|461}}</ref>
*Normal - shiny.
*Normal - shiny.
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**Gross: - (single) yellow patch or yellow nodules .
**Gross: - (single) yellow patch or yellow nodules .


==Sign-out==
==Placental mass==
Placental mass by gestational age:<ref>AFIP Placental pathol. ISBN: 1-881041-89-1. P.312</ref>
{| class="wikitable"
|Gest. Age/Percentile ||'''25%''' ||'''50%''' ||'''75%'''
|-
|'''32 weeks''' ||275 g ||318 g ||377 g
|-
|'''36 weeks''' ||369 g ||440 g ||508 g
|-
|'''40 weeks''' ||440 g ||501 g ||572 g
|-
|}
 
===Linear regression - placental mass-gestational age===
Based on the table in the AFIP book<ref>AFIP Placental pathol. ISBN: 1-881041-89-1. P.312</ref> I generated the following regression lines:
{| class="wikitable"
| ||'''50%''' ||'''10%''' ||'''90%'''
|-
|slope (g/week) ||21.58088235 ||19.70588235 ||25.40196078
|-
|y-intercept (g) ||-357.4558824 ||-397.2352941 ||-366.7254902
|-
|Pearson (r) ||0.988670724 ||0.988268672 ||0.982206408
|-
|}
 
placental mass = slope x gestational age + intercept
 
===What to remember...===
Extrapolated from the linear regression (see above):
*50% at term = 500 grams.
*50% at 26 weeks = 200 grams.
*The change in mass/week is approximately linear and equal to 300 grams / 14 weeks ~ 20 grams/week.
*The spread in mass between 10% and 90%, crudely estimated, is 200 grams (for GA=26-40).
 
=Sign-out=
What should be commented on...
What should be commented on...


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Mnemonic: ''chorio, cord, vessels, villi (maturity, infarction)''.
Mnemonic: ''chorio, cord, vessels, villi (maturity, infarction)''.


==Twin placentas==
=Twin placentas=
These are often submitted... even if they are normal.
 
==General==
No membrane between fetuses.
No membrane between fetuses.
*Split at approx. 7th day.
*Split at approx. 7th day.
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*If monozygotic -- split before 3 days.
*If monozygotic -- split before 3 days.


==Bleeding in late pregnancy==
=Diseases of the placental attachment=
DDx of bleeding in late pregnancy:
==Placenta acreta/percreta/increta==
*Placental abruption (most common).
Placenta attaches to the uterus deeper than it should.
*Placenta previa.
*Vasa previa (fetus losing blood).


==Placental abruption==
==Placental abruption==
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*There are '''no''' good microscopic findings for placental abruption.
*There are '''no''' good microscopic findings for placental abruption.


==Infection==
=Infection=
===General<ref name=Ref_PBoD1106>{{Ref PBoD|1106}}</ref>===
==General<ref name=Ref_PBoD1106>{{Ref PBoD|1106}}</ref>==
*Infection usually ascending, i.e. from vagina up through cervix.
*Infection usually ascending, i.e. from vagina up through cervix.
**Assoc. with intercourse.
**Assoc. with intercourse.
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*Placenta: placentitis, villitis.
*Placenta: placentitis, villitis.


===Grading infection (chorioamnionitis, membranitis, funisitis)===
==Grading infection (chorioamnionitis, membranitis, funisitis)==
Membranitis:<ref name=Ref_Sternberg4_2311>{{Ref Sternberg4|2311}}</ref>
Membranitis:<ref name=Ref_Sternberg4_2311>{{Ref Sternberg4|2311}}</ref>
# PMNs - decidua only.
# PMNs - decidua only.
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Note: There is no such thing as ''chorionitis''.<ref>ALS. February 2009.</ref>
Note: There is no such thing as ''chorionitis''.<ref>ALS. February 2009.</ref>


==Infarction==
=Infarction=
==True infarcts==
===General===
===General===
*Associated with retroplacental hematoma.
*Associated with retroplacental hematoma.
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*[http://library.med.utah.edu/WebPath/PLACHTML/PLAC044.html Placental infarcts (med.utah.edu)].
*[http://library.med.utah.edu/WebPath/PLACHTML/PLAC044.html Placental infarcts (med.utah.edu)].


===Microscopy===
===Microscopic===
Features:
Features:
*Loss of intervillous space.<ref name=Ref_WMSP465>{{Ref WMSP|465}}</ref>
*Loss of intervillous space.<ref name=Ref_WMSP465>{{Ref WMSP|465}}</ref>
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*> 3cm --or-- central location --or-- in 1st or 2nd trimester.
*> 3cm --or-- central location --or-- in 1st or 2nd trimester.
**Small foci are accepted in term placentae - typically at periphery.
**Small foci are accepted in term placentae - typically at periphery.
==Chorangioma==
===General===
*[[Hamartoma]]-like growth in the placenta consisting of [[blood vessel]]s.<ref name=pmid20594143>{{cite journal |author=Amer HZ, Heller DS |title=Chorangioma and related vascular lesions of the placenta--a review |journal=Fetal Pediatr Pathol |volume=29 |issue=4 |pages=199–206 |year=2010 |pmid=20594143 |doi=10.3109/15513815.2010.487009 |url=}}</ref>
===Epidemiology===
*Often benign.
*May be association with:
**Fetal maternal haemorrhage.
**Hydrops.
**[[IUGR]].
===Microscopy===
Features:
*Mass of capillaries.
Image:
*[http://commons.wikimedia.org/wiki/File:Chorangioma_-_intermed_mag.jpg Chorangioma (WC)].


==Perivillous fibrin deposition==
==Perivillous fibrin deposition==
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**Obliteration of intervillous space.
**Obliteration of intervillous space.


 
=Other=
==Passage of meconium==
==Passage of meconium==
===General===
===General===
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*Meconium contains bile.<ref>{{cite journal |author=Sienko A, Altshuler G |title=Meconium-induced umbilical vascular necrosis in abortuses and fetuses: a histopathologic study for cytokines |journal=Obstet Gynecol |volume=94 |issue=3 |pages=415?0 |year=1999 |month=September |pmid=10472870 |doi= |url=}}</ref>
*Meconium contains bile.<ref>{{cite journal |author=Sienko A, Altshuler G |title=Meconium-induced umbilical vascular necrosis in abortuses and fetuses: a histopathologic study for cytokines |journal=Obstet Gynecol |volume=94 |issue=3 |pages=415?0 |year=1999 |month=September |pmid=10472870 |doi= |url=}}</ref>


==Placental mass==
=Maternal disease=
Placental mass by gestational age:<ref>AFIP Placental pathol. ISBN: 1-881041-89-1. P.312</ref>
{| class="wikitable"
|Gest. Age/Percentile ||'''25%''' ||'''50%''' ||'''75%'''
|-
|'''32 weeks''' ||275 g ||318 g ||377 g
|-
|'''36 weeks''' ||369 g ||440 g ||508 g
|-
|'''40 weeks''' ||440 g ||501 g ||572 g
|-
|}
 
===Linear regression - placental mass-gestational age===
Based on the table in the AFIP book<ref>AFIP Placental pathol. ISBN: 1-881041-89-1. P.312</ref> I generated the following regression lines:
{| class="wikitable"
| ||'''50%''' ||'''10%''' ||'''90%'''
|-
|slope (g/week) ||21.58088235 ||19.70588235 ||25.40196078
|-
|y-intercept (g) ||-357.4558824 ||-397.2352941 ||-366.7254902
|-
|Pearson (r) ||0.988670724 ||0.988268672 ||0.982206408
|-
|}
 
placental mass = slope x gestational age + intercept
 
===What to remember...===
Extrapolated from the linear regression (see above):
*50% at term = 500 grams.
*50% at 26 weeks = 200 grams.
*The change in mass/week is approximately linear and equal to 300 grams / 14 weeks ~ 20 grams/week.
*The spread in mass between 10% and 90%, crudely estimated, is 200 grams (for GA=26-40).
 
==Hypertensive changes==
==Hypertensive changes==
Features:<ref name=pmid6754249>{{cite journal |author=Soma H, Yoshida K, Mukaida T, Tabuchi Y |title=Morphologic changes in the hypertensive placenta |journal=Contrib Gynecol Obstet |volume=9 |issue= |pages=58–75 |year=1982 |pmid=6754249 |doi= |url=}}</ref>
Features:<ref name=pmid6754249>{{cite journal |author=Soma H, Yoshida K, Mukaida T, Tabuchi Y |title=Morphologic changes in the hypertensive placenta |journal=Contrib Gynecol Obstet |volume=9 |issue= |pages=58–75 |year=1982 |pmid=6754249 |doi= |url=}}</ref>
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**In essence: severe ''hypertrophic decidual vasculopathy''. (???)
**In essence: severe ''hypertrophic decidual vasculopathy''. (???)


==Tumours==
=Tumours=
{{main|Gestational trophoblastic disease}}
{{main|Gestational trophoblastic disease}}


==Clinical screening tests==
==Chorangioma==
*PAPP-A - low values seen in aneuploidy.<ref>URL: [http://www.ncbi.nlm.nih.gov/sites/entrez?Db=gene&Cmd=ShowDetailView&TermToSearch=5069 http://www.ncbi.nlm.nih.gov/sites/entrez?Db=gene&Cmd=ShowDetailView&TermToSearch=5069]. Accessed on: 7 July 2010.</ref>
===General===
*[[Hamartoma]]-like growth in the placenta consisting of [[blood vessel]]s.<ref name=pmid20594143>{{cite journal |author=Amer HZ, Heller DS |title=Chorangioma and related vascular lesions of the placenta--a review |journal=Fetal Pediatr Pathol |volume=29 |issue=4 |pages=199–206 |year=2010 |pmid=20594143 |doi=10.3109/15513815.2010.487009 |url=}}</ref>
 
===Epidemiology===
*Often benign.
*May be association with:
**Fetal maternal haemorrhage.
**Hydrops.
**[[IUGR]].
 
===Microscopy===
Features:
*Mass of capillaries.


{{main|Pregnancy}}
Image:
*[http://commons.wikimedia.org/wiki/File:Chorangioma_-_intermed_mag.jpg Chorangioma (WC)].


==See also==
=See also=
*[[Chorionic villi]].
*[[Chorionic villi]].
*[[Endometrium]].
*[[Endometrium]].
*[[Pregnancy]].
*[[Pregnancy]].


==References==
=References=
{{reflist|2}}
{{reflist|2}}


[[Category:Gynecology]]
[[Category:Gynecology]]
Michael
48,466

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