Difference between revisions of "Placenta"

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Placenta (view source)

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The '''placenta''' feeds the developing baby, breathes for it and disposes of its waste.
[[Image:Human_placenta.jpg|thumb|right|A placenta (fetal aspect) with attached umbilical cord. (WC/Asturnut)]]
The '''placenta''' feeds the developing baby, breathes for it and disposes of its waste.  


=Clinical=
The organ is one that seems to be left behind; at least one review suggests it isn't done so well by general pathologists.<ref name=pmid12033960>{{Cite journal  | last1 = Sun | first1 = CC. | last2 = Revell | first2 = VO. | last3 = Belli | first3 = AJ. | last4 = Viscardi | first4 = RM. | title = Discrepancy in pathologic diagnosis of placental lesions. | journal = Arch Pathol Lab Med | volume = 126 | issue = 6 | pages = 706-9 | month = Jun | year = 2002 | doi = 10.1043/0003-9985(2002)1260706:DIPDOP2.0.CO;2 | PMID = 12033960 }}</ref>
 
''Placental pathology'' redirects to this article.
 
=Clinical=  
==Examination of the placenta==
==Examination of the placenta==
*Most placentas are ''not'' examined by a pathologist.
*Most placentas are ''not'' examined by a pathologist.
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*PPROM = preterm premature ruptures of membranes.
*PPROM = preterm premature ruptures of membranes.
*IUGR = [[intrauterine growth restriction]].
*IUGR = [[intrauterine growth restriction]].
*IOL = induction of labour.


=Normal histology=
=Normal histology=
Line 109: Line 115:
**Focal small deposits are considered to be a normal finding - seen in ~15% of cases.<ref name=pmid21393870>{{Cite journal  | last1 = Narasimha | first1 = A. | last2 = Vasudeva | first2 = DS. | title = Spectrum of changes in placenta in toxemia of pregnancy. | journal = Indian J Pathol Microbiol | volume = 54 | issue = 1 | pages = 15-20 | month =  | year =  | doi = 10.4103/0377-4929.77317 | PMID = 21393870 |URL = http://www.ijpmonline.org/article.asp?issn=0377-4929;year=2011;volume=54;issue=1;spage=15;epage=20;aulast=Narasimha }}</ref><ref>URL: [http://zulekhahospitals.com/uploads/files/Sub-chorionic.pdf http://zulekhahospitals.com/uploads/files/Sub-chorionic.pdf]. Accessed on: 17 August 2012.</ref>
**Focal small deposits are considered to be a normal finding - seen in ~15% of cases.<ref name=pmid21393870>{{Cite journal  | last1 = Narasimha | first1 = A. | last2 = Vasudeva | first2 = DS. | title = Spectrum of changes in placenta in toxemia of pregnancy. | journal = Indian J Pathol Microbiol | volume = 54 | issue = 1 | pages = 15-20 | month =  | year =  | doi = 10.4103/0377-4929.77317 | PMID = 21393870 |URL = http://www.ijpmonline.org/article.asp?issn=0377-4929;year=2011;volume=54;issue=1;spage=15;epage=20;aulast=Narasimha }}</ref><ref>URL: [http://zulekhahospitals.com/uploads/files/Sub-chorionic.pdf http://zulekhahospitals.com/uploads/files/Sub-chorionic.pdf]. Accessed on: 17 August 2012.</ref>
***The pathologic counterpart of this is ''[[perivillous fibrin deposition]]''.
***The pathologic counterpart of this is ''[[perivillous fibrin deposition]]''.
Image:
*[http://www.ijpmonline.org/viewimage.asp?img=IndianJPatholMicrobiol_2011_54_1_15_77317_u5.jpg Subchorionic fibrin deposition (ijpmonline.org)].


==Common terms==
==Common terms==
Line 187: Line 196:


===Linear regression - placental mass-gestational age===
===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:
Based on the table in the AFIP book<ref>AFIP Placental pathol. ISBN: 1-881041-89-1. P.312</ref> one can generate the following regression lines:
{| class="wikitable"
{| class="wikitable"
| ||'''50%''' ||'''10%''' ||'''90%'''
| ||'''50%''' ||'''10%''' ||'''90%'''
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*Is it required?
*Is it required?
**Sebire and Fox have advocated abandoning the practise of obtaining a placental mass, due to the large number of uncontrolled variables inherent in these measures.  Instead, they have advocated using mushy descriptors such as "small", "average" and "large", which require experience in examining the organ.<ref>{{cite book |author= Fox, Harold; Sebire, Neil J. |title=[http://www.amazon.com/Pathology-Placenta-Major-Problems/dp/1416025928/ref=sr_1_fkmr0_1?ie=UTF8&qid=1297259619&sr=1-1-fkmr0 Pathology of the Placenta (Major Problems in Pathology)]|publisher=Saunders |location= |year=2007 |pages= 559-561 |edition=3rd |isbn=978-1416025924 |oclc= |doi= |accessdate=}}</ref>   
**Sebire and Fox have advocated abandoning the practise of obtaining a placental mass, due to the large number of uncontrolled variables inherent in these measures.  Instead, they have advocated using mushy descriptors such as "small", "average" and "large", which require experience in examining the organ.<ref>{{cite book |author= Fox, Harold; Sebire, Neil J. |title=[http://www.amazon.com/Pathology-Placenta-Major-Problems/dp/1416025928/ref=sr_1_fkmr0_1?ie=UTF8&qid=1297259619&sr=1-1-fkmr0 Pathology of the Placenta (Major Problems in Pathology)]|publisher=Saunders |location= |year=2007 |pages= 559-561 |edition=3rd |isbn=978-1416025924 |oclc= |doi= |accessdate=}}</ref>   
***In the context of quality, a measure (even if somewhat flawed), is almost certainly more reproducible than arbitrary descriptors which require experience and a continuing case volume to calibrate.
***In the context of quality, a measure (even if somewhat flawed) is probably more reproducible and objective than arbitrary descriptors which require experience and a continuing case volume to calibrate.


===Placentomegaly===
===Placentomegaly===
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*[[AKA]] ''two vessel cord''.
*[[AKA]] ''two vessel cord''.
*[[AKA]] ''single umbilical artery''.
*[[AKA]] ''single umbilical artery''.
 
{{Main|Two vessel umbilical cord}}
===Associations===
*Associated with congenital abnormalities, esp. cardiac - '''key point'''.<ref name=Ref_WMSP464>{{Ref WMSP|464}}</ref>
**Thought to be an acquired defect (as prevalence is lower early in gestation).
*May be seen in association of other cord abnormalities (e.g. marginal insertion, velamentous insertion).
*In apparently well (liveborn) infants it is associated with (occult) renal abnormalities, specifically vesico-ureteric reflux; there is no evidence for other abnormalities.<ref name=pmid15613529>{{cite journal |author=Srinivasan R, Arora RS |title=Do well infants born with an isolated single umbilical artery need investigation? |journal=Arch. Dis. Child. |volume=90 |issue=1 |pages=100–1 |year=2005 |month=January |pmid=15613529 |pmc=1720078 |doi=10.1136/adc.2004.062372 |url=}}</ref>
*Associated with maternal [[diabetes]].<ref name=pmid7997408>{{cite journal |author=Lilja M |title=Infants with single umbilical artery studied in a national registry. 3: A case control study of risk factors |journal=Paediatr Perinat Epidemiol |volume=8 |issue=3 |pages=325–33 |year=1994 |month=July |pmid=7997408 |doi= |url=}}</ref>
 
Image:
*[http://www.glowm.com/resources/glowm/graphics/figures/v2/1070/05b.jpg SUA (glown.com)].<ref>URL: [http://www.glowm.com/?p=glowm.cml/section_view&articleid=151 http://www.glowm.com/?p=glowm.cml/section_view&articleid=151]. Accessed on: 8 January 2011.</ref>
 
===Sign out===
<pre>
PLACENTA, UMBILICAL CORD AND FETAL MEMBRANES, CAESAREAN SECTION:
- TWO VESSEL UMBILICAL CORD, NEGATIVE FOR INFLAMMATION.
- FETAL MEMBRANES WITHIN NORMAL LIMITS.
- PLACENTAL DISC WITH THIRD TRIMESTER VILLI WITHOUT APPARENT PATHOLOGY.
</pre>
 
====With meconium====
<pre>
PLACENTA, UMBILICAL CORD AND FETAL MEMBRANES, CAESAREAN SECTION:
- TWO VESSEL UMBILICAL CORD, NEGATIVE FOR INFLAMMATION.
- FETAL MEMBRANES WITH FOCAL PIGMENTED CELLS CONSISTENT WITH MECONIUM,
  NEGATIVE FOR APPARENT CHORIOAMNIONITIS.
- PLACENTAL DISC WITH THIRD TRIMESTER VILLI WITHOUT APPARENT PATHOLOGY.
</pre>


==Insertion==
==Insertion==
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*Rare ~ 1/5500.
*Rare ~ 1/5500.
*Mortality ~50% is severe.
*Mortality ~50% is severe.
Image: [http://flylib.com/books/2/953/1/html/2/43%20-%20Placenta_files/DA10C43FF12.png Hematoma (flylib.com)].<ref>URL: [http://flylib.com/books/en/2.953.1.49/1/ http://flylib.com/books/en/2.953.1.49/1/]. Accessed on: 10 January 2011.</ref>


=Membranes=
=Membranes=
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==Amnion nodosum==
==Amnion nodosum==
===General===
{{Main|Amnion nodosum}}
*Associated with (long-standing) oligohydramnios.<ref>URL: [http://library.med.utah.edu/WebPath/PLACHTML/PLAC042.html http://library.med.utah.edu/WebPath/PLACHTML/PLAC042.html]. Accessed on: 12 January 2011.</ref>
*Should be separated from ''squamous metaplasia of amnion''.
 
===Gross===
Features:<ref name=pmid18081444>{{Cite journal  | last1 = Adeniran | first1 = AJ. | last2 = Stanek | first2 = J. | title = Amnion nodosum revisited: clinicopathologic and placental correlations. | journal = Arch Pathol Lab Med | volume = 131 | issue = 12 | pages = 1829-33 | month = Dec | year = 2007 | doi = 10.1043/1543-2165(2007)131[1829:ANRCAP]2.0.CO;2 | PMID = 18081444 }}</ref>
*Yellow nodules ~ 1-5 mm.
**Some think they are white.<ref>CS. 7 February 2011.</ref>
 
DDx:
*[[Squamous metaplasia of the amnion]] - large irregular patches, usu. white.
 
Images:
*[http://www.webpathology.com/image.asp?n=2&Case=659 Amnion nodosum (webpathology.com)].
*[http://www.archivesofpathology.org/action/showFullPopup?id=i1543-2165-131-12-1829-f01&doi=10.1043%2F1543-2165%282007%29131%5B1829%3AANRCAP%5D2.0.CO%3B2 Amnion nodosum & squamous metaplasia of the amnion (archivesofpathology.org)].<ref name=pmid18081444/>
<!-- annoying use of '[' and ']' - had to go find escape characters here: http://www.w3schools.com/tags/ref_urlencode.asp -->
 
===Microscopic===
Features:<ref name=pmid18081444/>
*Stratified squamous epithelium - non-keratinizing ''or'' minimal keratin.
*Amorphous acidophilic (pink) debris.
 
Note:
*Normal amnion = simple epithelium.
 
Images:
*[http://www.webpathology.com/image.asp?case=659&n=3 Amnion nodosum (webpathology.com)].
*[http://www.archivesofpathology.org/action/showFullPopup?id=i1543-2165-131-12-1829-f01&doi=10.1043%2F1543-2165%282007%29131%5B1829%3AANRCAP%5D2.0.CO%3B2 Amnion nodosum & squamous metaplasia of the amnion (archivesofpathology.org)].<ref name=pmid18081444/>
<!-- annoying use of '[' and ']' - had to go find escape characters here: http://www.w3schools.com/tags/ref_urlencode.asp -->


==Placental meconium==
==Placental meconium==
Line 494: Line 447:


===Gross===
===Gross===
Features:<ref name=pmid18081444/>
Features:<ref name=pmid18081444>{{Cite journal  | last1 = Adeniran | first1 = AJ. | last2 = Stanek | first2 = J. | title = Amnion nodosum revisited: clinicopathologic and placental correlations. | journal = Arch Pathol Lab Med | volume = 131 | issue = 12 | pages = 1829-33 | month = Dec | year = 2007 | doi = 10.1043/1543-2165(2007)131[1829:ANRCAP]2.0.CO;2 | PMID = 18081444 }}</ref>
*White (or yellow) plaques - irregular outline.
*White (or yellow) plaques - irregular outline.


Line 568: Line 521:


==Villous hypoplasia==
==Villous hypoplasia==
*[[AKA]] ''terminal villus deficiency''.<ref name=Ref_Placenta246>{{Ref Placenta|346}}</ref>
*[[AKA]] ''terminal villus deficiency''.<ref name=Ref_Placenta346>{{Ref Placenta|346}}</ref>
 
{{Main|Villous hypoplasia}}
===General===
*Associated with [[IUGR]].<ref name=Ref_Placenta246>{{Ref Placenta|346}}</ref>
*Atypical Doppler flow measurements: high Doppler resistance index.<ref name=Ref_Placenta246>{{Ref Placenta|346}}</ref>
 
===Microscopic===
Features:<ref name=Ref_Placenta246>{{Ref Placenta|346}}</ref>
*Small, round villi (30-60 micrometers).
*"Long" villi (due to lack of branching).
*Absence of syncytial knotts.
*Wide intervillous space.


=Diseases of the placental attachment=
=Diseases of the placental attachment=
==Placenta creta==
==Placenta creta==
*What?
Includes ''placenta accreta'', ''placenta increta'', and ''placenta percreta''.
**Trophoblastic tissue deeper than it should be.
{{Main|Placenta creta}}
*Clinical?
**Postpartum hemorrhage leading to a hysterectomy.<ref name=pmid18514815>{{Cite journal  | last1 = Tantbirojn | first1 = P. | last2 = Crum | first2 = CP. | last3 = Parast | first3 = MM. | title = Pathophysiology of placenta creta: the role of decidua and extravillous trophoblast. | journal = Placenta | volume = 29 | issue = 7 | pages = 639-45 | month = Jul | year = 2008 | doi = 10.1016/j.placenta.2008.04.008 | PMID = 18514815 }}</ref>
*Pathogenesis?
**It is suspected that it arises as there is defect in the endometrium/myometrium -- ''not'' deep trophoblastic invasion.<ref name=pmid18514815/>
**Risk factors:<ref name=pmid23466142>{{Cite journal  | last1 = Wortman | first1 = AC. | last2 = Alexander | first2 = JM. | title = Placenta accreta, increta, and percreta. | journal = Obstet Gynecol Clin North Am | volume = 40 | issue = 1 | pages = 137-54 | month = Mar | year = 2013 | doi = 10.1016/j.ogc.2012.12.002 | PMID = 23466142 }}</ref>
***Placenta previa.
***Previous caesarian section.
 
Note:
*Normal: trophoblastic tissue attaches to the decidua.<ref name=Ref_Pathde_974>{{Ref Pathde|974}}</ref>
 
===Placenta accreta===
*Trophoblastic tissue (directly) adherent to the myometrium.<ref name=Ref_Pathde_974>{{Ref Pathde|974}}</ref>
 
Image:
*[http://library.med.utah.edu/WebPath/jpeg2/PLAC040.jpg Placenta accreta (med.utah.edu)].<ref>URL: [http://library.med.utah.edu/WebPath/EXAM/IMGQUIZ/plfrm.html http://library.med.utah.edu/WebPath/EXAM/IMGQUIZ/plfrm.html]. Accessed on: 3 December 2011.</ref>
 
===Placenta increta===
*Trophoblastic tissue extends into the myometrium.
 
===Placenta percreta===
*Trophoblastic tissue penetrates through the myometrium.


==Placental abruption==
==Placental abruption==
===General===
{{Main|Placental abruption}}
Classic clinical manifestations:<ref name=pmid16752262>{{cite journal |author=Tikkanen M, Nuutila M, Hiilesmaa V, Paavonen J, Ylikorkala O |title=Clinical presentation and risk factors of placental abruption |journal=Acta Obstet Gynecol Scand |volume=85 |issue=6 |pages=700–5 |year=2006 |pmid=16752262 |doi=10.1080/00016340500449915 |url=}}</ref>
*Vaginal bleeding (~70%).
*Abdominal pain (~50%).
*Fetal heart rate abnormalities (~70%).
 
Sign-out:
*Pathologists should sign-out this as "focal adherent retroplacental hematoma".
**The pathologic findings may be due to abruption or manual removal of the placenta.
 
===Gross===
Features:<ref>CS. 7 February 2011.</ref>
*Large adherent blood clot.
*Disc depression on maternal side.
 
Notes:
*Loosely attached clot less convincing.
*Central haemorrhage is the most worrisome.
 
===Microscopic===
Features:
#Decidual hemorrhage.
#*Blood in the decidua.
#Intravillous hemorrhage, [[AKA]] villous stromal hemorrhage.
#*"Bags of blood" - blood outside of vessels in the villi.
#**Should not be confused with congested villi.
 
Notes:
*There are '''no''' definitive microscopic findings for placental abruption.
*Intravillous hemorrhage is non-specific - may arise in the following: early placental infarct, cord compression, abdominal trauma.
===Sign out===
====Usual nonspecific findings====
<pre>
PLACENTA, UMBILICAL CORD AND FETAL MEMBRANES, BIRTH:
- THREE VESSEL UMBILICAL CORD WITHIN NORMAL LIMITS.
- FETAL MEMBRANES WITHIN NORMAL LIMITS.
- PLACENTAL DISC WITH THIRD TRIMESTER VILLI, TWO SMALL PLACENTAL INFARCTS
  (0.8 CM AND 0.5 CM IN MAXIMAL DIMENSION) AND FOCAL PROMINENCE OF SYNCYTIAL KNOTS.
 
COMMENT:
There is no decidual hemorrhage or intravillous hemorrhage. The prominent syncytial knots
are a nonspecific finding suggestive of (focal) ischemia.
</pre>
Note:
*The above is not diagnostic nor does it exclude the diagnosis of abruption.


=Inflammatory pathologies=
=Inflammatory pathologies=
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<pre>
<pre>
PLACENTA, UMBILICAL CORD AND FETAL MEMBRANES, CESAERIAN SECTION:
PLACENTA, UMBILICAL CORD AND FETAL MEMBRANES, CESAERIAN SECTION:
- FETAL MEMBRANES WITH CHORIONITIS.
- THREE VESSEL UMBILICAL CORD WITH VASCULITIS.
- THREE VESSEL UMBILICAL CORD WITH VASCULITIS.
- FETAL MEMBRANES WITH CHORIONITIS.
- PLACENTAL DISC WITH THIRD TRIMESTER VILLI.
- PLACENTAL DISC WITH THIRD TRIMESTER VILLI.
</pre>
====Waffle====
<pre>
PLACENTA, UMBILICAL CORD AND FETAL MEMBRANES, BIRTH:
- FETAL MEMBRANES WITH MECONIUM-LADEN MACROPHAGES AND ABUNDANT DECIDUAL NEUTROPHILS
  SUSPICIOUS FOR EARLY CHORIONITIS.
- PLACENTAL DISC WITH THIRD TRIMESTER VILLI.
- THREE VESSEL UMBILICAL CORD WITHIN NORMAL LIMITS.
</pre>
</pre>


Line 707: Line 593:


==Umbilical cord vasculitis==
==Umbilical cord vasculitis==
===General===
{{Main|Umbilical cord vasculitis}}
*Usually seen together with [[chorioamnionitis]].
**May be described as the ''fetal response'' to chorioamnionitis.<ref name=pmid14749651/>
*Presence considered to be a good prognosticator.<ref name=pmid14749651>{{Cite journal  | last1 = Lahra | first1 = MM. | last2 = Jeffery | first2 = HE. | title = A fetal response to chorioamnionitis is associated with early survival after preterm birth. | journal = Am J Obstet Gynecol | volume = 190 | issue = 1 | pages = 147-51 | month = Jan | year = 2004 | doi = 10.1016/j.ajog.2003.07.012 | PMID = 14749651 }}
</ref>
 
===Microscopic===
Features:
*[[Neutrophil]]s in the vessels of the umbilical cord.
*Wharton's jelly without neutrophils.
 
Note:
*Umbilical vein involvement (umbilical phlebitis) precedes umbilical artery involvement (umbilical arteritis).<ref name=pmid21090086>{{Cite journal  | last1 = Vedovato | first1 = S. | last2 = Zanardo | first2 = V. | title = [Chorioamnionitis and inflammatory disease in the premature newborn infant]. | journal = Minerva Pediatr | volume = 62 | issue = 3 Suppl 1 | pages = 155-6 | month = Jun | year = 2010 | doi =  | PMID = 21090086 }}</ref>
 
DDx:
*[[Funisitis]] - neutrophils also in the connective tissue of the umbilical cord (Wharton's jelly).
 
====Grading====
Umbilical cord vasculitis:<ref name=Ref_Sternberg4_2311>{{Ref Sternberg4|2311}}</ref>
* +0.5 for each vessel.
* +0.5 for each vessel with severe involvement.


==Funisitis==
==Funisitis==
===General===
{{Main|Funisitis}}
*Usu. seen together with [[chorioamnionitis]].
*Inflammation of Wharton's jelly - the connective tissue of the umbilical cord.
 
===Microscopic===
Features:
*Neutrophils in the vessels of the umbilical cord and Wharton's jelly.
 
Note:
*Wharton's jelly = connective tissue of the umbilical cord.
 
DDx:
*[[Umbilical cord vasculitis]] - neutrophils only in the vessel wall.
 
====Grading funisitis====
Funisitis:<ref name=Ref_Sternberg4_2311>{{Ref Sternberg4|2311}}</ref>
# Focal inflammation.
# Diffuse inflammation.
# Necrosis - in umbilical vessels or Wharton jelly.
 
===Sign out===
<pre>
PLACENTA, UMBILICAL CORD AND FETAL MEMBRANES, BIRTH:
- CHORIOAMNIONITIS.
- THREE VESSEL UMBILICAL CORD WITH FUNISITIS.
- PLACENTAL DISC WITH THIRD TRIMESTER VILLI.
- TWO THROMBI OF THE PLACENTAL DISC (LARGEST 0.9 CM - MAXIMAL DIMENSION).
</pre>


==Acute villitis==
==Acute villitis==
===General===
{{main|Acute villitis}}
*Rare.
*Typically viral - see ''[[TORCH infections]]''.
 
===Microscopic===
Features:
*[[Neutrophil]]s in the villous stroma - '''key feature'''.
*+/-Features suggestive a particular infective etiology.
**Cytoplasmic inclusion +/-owl's eye nucleus ([[CMV]]).
 
====Images====
<gallery>
Image:CMV_placentitis2_mini.jpg | [[CMV]] placentitis. (WC)
</gallery>
www:
*[http://www.webpathology.com/image.asp?n=1&Case=579 Acute villitis (webpathology.com)].
*[http://www.webpathology.com/image.asp?n=2&Case=579 Acute villitis (webpathology.com)].


==Villitis of unknown etiology==
==Villitis of unknown etiology==
Line 801: Line 626:
==Chronic deciduitis==
==Chronic deciduitis==
*[[AKA]] plasma cell deciduitis.
*[[AKA]] plasma cell deciduitis.
{{Main|Chronic deciduitis}}


===General===
*Associated with preterm labour.<ref name=pmid18171100>{{Cite journal  | last1 = Edmondson | first1 = N. | last2 = Bocking | first2 = A. | last3 = Machin | first3 = G. | last4 = Rizek | first4 = R. | last5 = Watson | first5 = C. | last6 = Keating | first6 = S. | title = The prevalence of chronic deciduitis in cases of preterm labor without clinical chorioamnionitis. | journal = Pediatr Dev Pathol | volume = 12 | issue = 1 | pages = 16-21 | month =  | year =  | doi = 10.2350/07-04-0270.1 | PMID = 18171100 }}</ref>
===Microscopic===
Features:<ref name=pmid18171100/>
*Plasma cells within the decidua.
Notes:
*Decidua = maternal tissue.
====Images====
<gallery>
Image:Chronic_deciduitis_-_intermed_mag.jpg | Chronic deciduitis - intermed. mag. (WC)
Image:Chronic_deciduitis_-_very_high_mag.jpg | Chronic deciduitis - very high mag. (WC)
</gallery>
=Placental infarction=
=Placental infarction=
==True infarcts==
==True infarcts==
{{Main|Infarction}}
{{Main|Placental infarct}}
===General===
*May be seen in conjunction with a retroplacental hematoma.
*Infarcts frequently associated with [[hypertension]].<ref>URL: [http://www.medind.nic.in/jae/t04/i1/jaet04i1p27.pdf http://www.medind.nic.in/jae/t04/i1/jaet04i1p27.pdf]. Accessed on: 16 April 2012.</ref><ref name=pmid11969346>{{Cite journal  | last1 = Becroft | first1 = DM. | last2 = Thompson | first2 = JM. | last3 = Mitchell | first3 = EA. | title = The epidemiology of placental infarction at term. | journal = Placenta | volume = 23 | issue = 4 | pages = 343-51 | month = Apr | year = 2002 | doi = 10.1053/plac.2001.0777 | PMID = 11969346 }}</ref>
 
Note: "[[Maternal floor infarct]]" is ''not'' a true infarct.<ref name=Ref_TPoSP178>{{Ref TPoSP|178}}</ref>
 
===Gross===
Features:<ref name=Ref_WMSP465>{{Ref WMSP|465}}</ref>
*Early - red.
*Late - white/grey.
 
====Significant infarcts====
*> 3cm --or-- central location --or-- in 1st or 2nd trimester.{{fact}}
**Small foci are accepted in term placentae - typically at periphery.
 
Images:
*[http://pathweb.uchc.edu/eatlas/gyn/681b.htm Placental infarcts (pathweb.uchc.edu)].
*[http://library.med.utah.edu/WebPath/PLACHTML/PLAC044.html Placental infarcts (med.utah.edu)].
 
===Microscopic===
Features:
#Necrosis of villi; hyaline material (acellular eosinophilic material) replaces the stroma of the villi.
#Loss of intervillous space.<ref name=Ref_WMSP465>{{Ref WMSP|465}}</ref>
#*Villi appear to be crowded.<ref>{{Ref PBoD|1109}}</ref>
#**Normal spacing is ~1x smallest villus or larger.
#***In perivillous fibrin deposition - spacing usu. larger than normal.
#Increased numbers of villi with syncytial knots. ‡
#Thickened trophoblastic basement membrane (below [[cytotrophoblast]]s).
#+/-Changes seen in decidual vasculopathy:
#*Acute atherosis (vaguely like [[atherosclerosis]]).
#**[[Fibrinoid necrosis]].
#**Vessel wall lipid deposition.
 
Note:
*‡ The normal number is dependent on the gestational age:<ref name=pmid20017638>{{Cite journal  | last1 = Loukeris | first1 = K. | last2 = Sela | first2 = R. | last3 = Baergen | first3 = RN. | title = Syncytial knots as a reflection of placental maturity: reference values for 20 to 40 weeks' gestational age. | journal = Pediatr Dev Pathol | volume = 13 | issue = 4 | pages = 305-9 | month =  | year =  | doi = 10.2350/09-08-0692-OA.1 | PMID = 20017638 }}</ref>
<center>
{| class="wikitable sortable"
! Gestational age
! Villi with knots<br> (average)
! Villi with knots<br> (range)
|-
| 40 weeks
| 29 %
| 27-36 %
|-
| 39 weeks
| 29 %
| 23-34%
|-
| 38 weeks
| 27 %
| 23-33 %
|-
| 37 weeks
| 28 %
| 24-33 %
|-
| 36 weeks
| 23 %
| 20-26 %
|-
| 35 weeks
| 22 %
| 15-32 %
|-
| 34 weeks
| 18 %
| 12-22 %
|-
| 32 weeks
| 13 %
| 10-16 %
|-
| 30 weeks
| 13 %
| 10-17 %
|-
| 26 weeks
| 11 %
| 10-13 %
|-
| 22 weeks
| 7 %
| 5-9 %
|}
</center>
 
====Images====
<gallery>
Image:Placental_infarct_-_low_mag.jpg | Placental infarct - low mag. (WC)
Image:Placental_infarct_-_intermed_mag.jpg | Placental infarct - intermed. mag. (WC)
</gallery>
www:
*[http://pathweb.uchc.edu/eatlas/gyn/1203b.htm Recent infarct (pathweb.uchc.edu)].
*[http://path.upmc.edu/cases/case75/images/micro1.jpg Placental infarct (umpmc.edu)].<ref>URL: [http://path.upmc.edu/cases/case75/micro.html http://path.upmc.edu/cases/case75/micro.html]. Accessed on: 6 January 2011.</ref>
*[http://www.mda-sy.com/pathology/PLACHTML/PLAC024.HTM Placental infarct - necrotic villi (mda-sy.com)].
 
===Sign out===
<pre>
PLACENTA, UMBILICAL CORD AND FETAL MEMBRANES, BIRTH:
- THREE VESSEL UMBILICAL CORD WITHIN NORMAL LIMITS.
- FETAL MEMBRANES WITHIN NORMAL LIMITS.
- PLACENTAL DISC WITH THIRD TRIMESTER VILLI AND TWO PLACENTAL INFARCTS (0.6 CM AND
  0.4 CM IN MAXIMAL DIMENSION).
</pre>
 
====Increased syncytial knots====
<pre>
PLACENTA, UMBILICAL CORD AND FETAL MEMBRANES, BIRTH:
- THREE VESSEL UMBILICAL CORD WITHIN NORMAL LIMITS.
- FETAL MEMBRANES WITHIN NORMAL LIMITS.
- PLACENTAL DISC WITH THIRD TRIMESTER VILLI WITH FOCALLY INCREASED SYNCYTIAL KNOTS,
  AND MILD PERIVILLOUS FIBRIN DEPOSITION, OTHERWISE WITHIN NORMAL LIMITS.
</pre>


==Perivillous fibrin deposition==
==Perivillous fibrin deposition==
*Abbreviation ''PFD''.
*Abbreviation ''PFD''.
===General===
===General===
*Thought to be an immunologic problem - resulting in platelet activation and fibrin deposition.<ref name=pmid12066949/>
*Thought to be an immunologic problem - resulting in platelet activation and fibrin deposition.<ref name=pmid12066949>{{Cite journal  | last1 = Sebire | first1 = NJ. | last2 = Backos | first2 = M. | last3 = Goldin | first3 = RD. | last4 = Regan | first4 = L. | title = Placental massive perivillous fibrin deposition associated with antiphospholipid antibody syndrome. | journal = BJOG | volume = 109 | issue = 5 | pages = 570-3 | month = May | year = 2002 | doi =  | PMID = 12066949 }}</ref>
*May be associated with [[diabetes mellitus]].<ref name=Ref_Placenta327>{{Ref Placenta|327}}</ref>
*May be associated with [[diabetes mellitus]].<ref name=Ref_Placenta327>{{Ref Placenta|327}}</ref>


Line 977: Line 674:
*Formally ''placental maternal floor infarction''.
*Formally ''placental maternal floor infarction''.
*[[AKA]] ''massive perivillous fibrin deposition''.<ref name=Ref_Placenta367>{{Ref Placenta|367}}</ref>
*[[AKA]] ''massive perivillous fibrin deposition''.<ref name=Ref_Placenta367>{{Ref Placenta|367}}</ref>
===General===
{{Main|Maternal floor infarction}}
*'''''Not''''' a true infact.
**It is really fibrin deposition.<ref name=Ref_TPoSP178>{{Ref TPoSP|178}}</ref>
 
Associations:
*[[Intrauterine growth restriction]] (IUGR).<ref name=pmid18641412>{{Cite journal  | last1 = Roberts | first1 = DJ. | last2 = Post | first2 = MD. | title = The placenta in pre-eclampsia and intrauterine growth restriction. | journal = J Clin Pathol | volume = 61 | issue = 12 | pages = 1254-60 | month = Dec | year = 2008 | doi = 10.1136/jcp.2008.055236 | PMID = 18641412 }}</ref><ref name=pmid11910510>{{Cite journal  | last1 = Katzman | first1 = PJ. | last2 = Genest | first2 = DR. | title = Maternal floor infarction and massive perivillous fibrin deposition: histological definitions, association with intrauterine fetal growth restriction, and risk of recurrence. | journal = Pediatr Dev Pathol | volume = 5 | issue = 2 | pages = 159-64 | month =  | year =  | doi = 10.1007/s10024-001-0195-y | PMID = 11910510 }}</ref>
*Anti-phospholipid antibody (APLA) syndrome.<ref name=pmid12066949>{{cite journal |author=Sebire NJ, Backos M, Goldin RD, Regan L |title=Placental massive perivillous fibrin deposition associated with antiphospholipid antibody syndrome |journal=BJOG |volume=109 |issue=5 |pages=570–3 |year=2002 |month=May |pmid=12066949 |doi= |url=http://www3.interscience.wiley.com/resolve/openurl?genre=article&sid=nlm:pubmed&issn=1470-0328&date=2002&volume=109&issue=5&spage=570}}</ref>
**APLA is associated with recurrent miscarriage - can be treated with heparin + ASA.<ref name=pmid12066949/>
*Pregnancy-induced [[hypertension]].<ref name=pmid8569189>{{Cite journal  | last1 = Kanfer | first1 = A. | last2 = Bruch | first2 = JF. | last3 = Nguyen | first3 = G. | last4 = He | first4 = CJ. | last5 = Delarue | first5 = F. | last6 = Flahault | first6 = A. | last7 = Nessmann | first7 = C. | last8 = Uzan | first8 = S. | title = Increased placental antifibrinolytic potential and fibrin deposits in pregnancy-induced hypertension and preeclampsia. | journal = Lab Invest | volume = 74 | issue = 1 | pages = 253-8 | month = Jan | year = 1996 | doi =  | PMID = 8569189 }}</ref>
 
===Gross===
Features:<ref name=Ref_Placenta368>{{Ref Placenta|368}}</ref>
*+/-Thickened placenta.
*Maternal aspect of placental disc irregular or lobulated appearance.
*+/-Yellowish discolourization.
 
===Microscopic===
Features:
*Extensive fibrin deposition around villi on maternal aspect - see: ''[[Perivillous fibrin deposition]]''.
**Described as having a "net-like" pattern.<ref name=Ref_Placenta368>{{Ref Placenta|368}}</ref>
**"Extensive" - either of the following:<ref name=pmid11910510/><ref>AFIP - Placental Pathology. P.135. ISBN: 1-881041-89-1. 2004.</ref>
**#Micro: one slide with >50% of villi involved.
**#*Gross: full thickness involvement.
**#Micro: maternal floor has at least 3 mm of fibrin on one slide.
**#*Gross: maternal floor diffusely involved.
 
DDx:
*[[Perivillous fibrin deposition]] - less perivillous fibrin.
*[[Placental infarction]].
 
Images:
*[http://www.flickr.com/photos/jian-hua_qiao_md/3987724630/ Maternal floor infarct (flickr.com)].
*[http://www.flickr.com/photos/jian-hua_qiao_md/3986970923/ Maternal floor infarct (flickr.com)].
*[http://path.upmc.edu/cases/case224.html Maternal floor infarct - several images (upmc.edu)].
 
===Sign out===
<pre>
PLACENTA, UMBILICAL CORD AND FETAL MEMBRANES, BIRTH:
- THREE VESSEL UMBILICAL CORD WITHIN NORMAL LIMITS.
- FETAL MEMBRANES WITHIN NORMAL LIMITS.
- SMALL PLACENTAL DISC WITH MASSIVE PERIVILLOUS FIBRIN DEPOSITION, SEE COMMENT.
 
COMMENT:
Massive perivillous fibrin deposition (MPVFD) is associated with intrauterine
growth restriction (IUGR). MPVFD is described in association with in
anti-phospholipid antibody (APLA) syndrome, pregnancy-induced hypertension and
congenital infections. Perivillous fibrin deposition may be seen in diabetes.
 
There is no apparent infection. Changes suggestive of decidual vasculopathy
are not apparent. Changes suggestive of fetal thrombotic vasculopathy are
not identified.
</pre>


=Fetal disease=
=Fetal disease=
Line 1,038: Line 684:
**''Fetal artery stem thrombosis''.
**''Fetal artery stem thrombosis''.
*The multitude of terms reflects the confusion about this finding and that it has numerous etiologies.<ref name=pmid19237859/>
*The multitude of terms reflects the confusion about this finding and that it has numerous etiologies.<ref name=pmid19237859/>
===General===
{{Main|Fetal thrombotic vasculopathy}}
*May cause [[IUGR]].
*Associated with cerebral palsy and common in perinatal deaths.<ref name=pmid10414494>{{cite journal |author=Kraus FT, Acheen VI |title=Fetal thrombotic vasculopathy in the placenta: cerebral thrombi and infarcts, coagulopathies, and cerebral palsy |journal=Hum. Pathol. |volume=30 |issue=7 |pages=759–69 |year=1999 |month=July |pmid=10414494 |doi= |url=}}</ref>
 
===Microscopic===
Features:<ref name=pmid10414494>{{Cite journal  | last1 = Kraus | first1 = FT. | last2 = Acheen | first2 = VI. | title = Fetal thrombotic vasculopathy in the placenta: cerebral thrombi and infarcts, coagulopathies, and cerebral palsy. | journal = Hum Pathol | volume = 30 | issue = 7 | pages = 759-69 | month = Jul | year = 1999 | doi =  | PMID = 10414494 }}</ref>
*Thrombus in the fetal vasculature +/- recanalization.
**Eosinophilic (light pink on H&E), moderately granular intravascular material (fibrin) with layering.
*Clustered fibrotic villi without blood vessels - '''key feature'''.
**This is a chronic change.


====Images====
www:
*[http://jcp.bmj.com/content/61/12/1254/F8.large.jpg FTV (bmj.com)].<ref>URL: [http://jcp.bmj.com/content/61/12/1254.abstract http://jcp.bmj.com/content/61/12/1254.abstract]. Accessed on: 12 January 2011.</ref>
*[http://gut.bmj.com/content/41/3/354/F3.large.jpg Thrombus - rat (bmj.com)].<ref>URL: [http://gut.bmj.com/content/41/3/354.full http://gut.bmj.com/content/41/3/354.full]. Accessed on: 12 January 2011.</ref>
*[http://www.womenandinfants.org/fertilityandpregnancy/images/FTV.Fig.4a.jpg FTV - low mag. (womenandinfants.org)].<ref>URL: [http://www.womenandinfants.org/fertilityandpregnancy/current-topics-in-perinatal-pathology.cfm http://www.womenandinfants.org/fertilityandpregnancy/current-topics-in-perinatal-pathology.cfm]. Accessed on: 17 December 2012.</ref>
*[http://www.womenandinfants.org/fertilityandpregnancy/images/FTV.Fig.4b.jpg FTV - high mag. (womenandinfants.org)].
<gallery>
Image:Fetal_thrombotic_vasculopathy_-_intermed_mag.jpg | FTV - intermed. mag. (WC)
Image:Fetal_thrombotic_vasculopathy_-_high_mag.jpg | FTV - high mag. (WC)
</gallery>
==Hemorrhagic endovasculitis==
==Hemorrhagic endovasculitis==
*Abbreviated ''HEV''.
*Abbreviated ''HEV''.
Line 1,092: Line 719:


==Hypertrophic decidual vasculopathy==
==Hypertrophic decidual vasculopathy==
:''Decidual vasculopathy'' redirects here.
:[[AKA]] ''decidual vasculopathy''.
===General===
{{Main|Hypertrophic decidual vasculopathy}}
*A change seen in hypertension.
*Seen in [[intrauterine growth restriction]] (IUGR).
 
===Microscopic===
Features:<ref name=pmid18641412>{{Cite journal  | last1 = Roberts | first1 = DJ. | last2 = Post | first2 = MD. | title = The placenta in pre-eclampsia and intrauterine growth restriction. | journal = J Clin Pathol | volume = 61 | issue = 12 | pages = 1254-60 | month = Dec | year = 2008 | doi = 10.1136/jcp.2008.055236 | PMID = 18641412 }}</ref>
*Mild or moderate:
*#Perivascular inflammatory cells.
*#+/-Vascular [[thrombosis]].
*#Smooth muscle hypertrophy.
*#Endothelial hyperplasia.
*#*Above two lead to narrowing of the decidual spiral arteries<ref>AFIP - Placental Pathology. P.122. ISBN: 1-881041-89-1. 2004.</ref> -- '''key feature'''.
*Severe:<ref name=pmid18641412/>
*#Atherosis of maternal blood vessels.
*#*Foamy macrophages within vascular wall.
*#[[Fibrinoid necrosis]] of vessel wall (amorphous eosinophilic material vessel wall).
*Suggestive:<ref>{{Ref Placenta|339}}</ref>
**Decidual vasculitis - lymphocyte predominant without plasma cells.
 
Note:
*''Smooth muscle hypertrophy'' can also be understood as ''lack of physiological conversion of spiral arteries of the uterus''.<ref name=pmid12848643>{{Cite journal  | last1 = Naicker | first1 = T. | last2 = Khedun | first2 = SM. | last3 = Moodley | first3 = J. | last4 = Pijnenborg | first4 = R. | title = Quantitative analysis of trophoblast invasion in preeclampsia. | journal = Acta Obstet Gynecol Scand | volume = 82 | issue = 8 | pages = 722-9 | month = Aug | year = 2003 | doi =  | PMID = 12848643 }}</ref>
 
====Images====
<gallery>
Image:Hypertrophic_decidual_vasculopathy_intermed_mag.jpg | HDV - intermed. mag. (WC)
Image:Hypertrophic_decidual_vasculopathy_low_mag.jpg | HDV - low mag. (WC)
</gallery>
www:
*[http://path.upmc.edu/cases/case75/images/micro2.jpg Atherosis (upmc.edu)].<ref>URL: [http://path.upmc.edu/cases/case75.html http://path.upmc.edu/cases/case75.html]. Accessed on: 2 January 2012.</ref>
*[http://www.surgpath4u.com/caseviewer.php?case_no=490 Decidual vasculopathy (surgpath4u.com)].
*[http://www.brown.edu/Courses/Digital_Path/systemic_path/cardio/decidualvasculopathy.html Decidual vasculopathy (brown.edu)].
 
===Sign out===
<pre>
PLACENTA, UMBILICAL CORD AND FETAL MEMBRANES, CESAREAN SECTION:
- DECIDUAL VASCULOPATHY.
- PLACENTA SMALL FOR GESTATIONAL AGE (222 GRAMS).
- PLACENTAL DISC WITH EARLY THIRD TRIMESTER VILLI WITH:
-- MULTIPLE PLACENTAL INFARCTS.
-- PERIVILLOUS FIBRIN DEPOSITION.
- THREE VESSEL UMBILICAL CORD WITHIN NORMAL LIMITS.
- FETAL MEMBRANES WITHIN NORMAL LIMITS.
 
COMMENT:
The 10th percentile placental mass (pre-fixation) for 32 weeks and 6
days is approximately 247 grams.
</pre>
 
====Suggestive of decidual vasculopathy====
<pre>
PLACENTA, UMBILICAL CORD AND FETAL MEMBRANES, CESAREAN SECTION:
- CHANGES SUGGESTIVE OF DECIDUAL VASCULOPATHY (DECIDUAL VASCULITIS).
- PLACENTAL DISC WITH EARLY THIRD TRIMESTER VILLI AND A PLACENTAL INFARCT
  (2.5 CM IN MAXIMAL DIMENSION).
- THREE VESSEL UMBILICAL CORD WITHIN NORMAL LIMITS.
- FETAL MEMBRANES WITHIN NORMAL LIMITS.
</pre>


==HELLP syndrome==
==HELLP syndrome==
===General===
{{Main|HELLP syndrome}}
*Diagnosed clinically.
*Pathologically not the same as ''severe preclampsia''.<ref name=pmid18362224>{{cite journal |author=Vinnars MT, Wijnaendts LC, Westgren M, Bolte AC, Papadogiannakis N, Nasiell J |title=Severe preeclampsia with and without HELLP differ with regard to placental pathology |journal=Hypertension |volume=51 |issue=5 |pages=1295–9 |year=2008 |month=May |pmid=18362224 |doi=10.1161/HYPERTENSIONAHA.107.104844 |url=}}</ref>
 
Definition:
*'''H''' = hemolysis.
*'''EL''' = elevated liver enzymes.
*'''LP''' = low platelets.
 
===Microscopic===
Features:<ref name=pmid7966086>{{cite journal |author=Ornstein MH, Rand JH |title=An association between refractory HELLP syndrome and antiphospholipid antibodies during pregnancy; a report of 2 cases |journal=J. Rheumatol. |volume=21 |issue=7 |pages=1360–4 |year=1994 |month=July |pmid=7966086 |doi= |url=}}</ref>
*Thrombotic microangiopathic vasculopathy.
**In essence: severe ''hypertrophic decidual vasculopathy''. (???)


==Malaria==
==Malaria==
Line 1,209: Line 768:
*May be spelled ''foetus papyraceus''.
*May be spelled ''foetus papyraceus''.
*[[AKA]] ''fetus compressus''.
*[[AKA]] ''fetus compressus''.
 
{{Main|Fetus papyraceus}}
===General===
*Remnant of a dead fetus usu. from a twin pregnancy.
**No clinical consequence for mother and remaining fetus.
 
Clinical:<ref name=Ref_Placenta141>{{Ref Placenta|141}}</ref>
*Documented multiple gestation by imaging.
*Elevated AFP.
*May be a "fetal reduction" in the context of ''in vitro'' fertilization (IVF).
 
Note:
*"Papyraceus" = paper-like.
 
===Gross===
*Pale yellow flattened disk or plaque with a pigmented macule<ref name=Ref_Placenta141>{{Ref Placenta|141}}</ref> - on membranes or placental disc.
 
===Microscopic===
Features:
*Fetal structures - such as:
**Cartilage.
**Bone.
 
Images:
*[http://www.nejm.org/doi/full/10.1056/NEJMicm020196 Fetus papyraceus (nejm.org)].
*[http://path.upmc.edu/cases/case128.html Fetus papyraceus (upmc.edu)].
*[http://www.neonet.ch/en/03_Case_of_the_month/archive/11_dermatologic_disorders/2002_10.asp Fetus papyraceus (neonet.ch)].<ref>URL: [http://www.neonet.ch/en/03_Case_of_the_month/archive/11_dermatologic_disorders/2002_10.asp http://www.neonet.ch/en/03_Case_of_the_month/archive/11_dermatologic_disorders/2002_10.asp]. Accessed on: 3 January 2012.</ref>


==Placental mesenchymal dysplasia==
==Placental mesenchymal dysplasia==
*Abbreviated ''PMD''.
*Abbreviated ''PMD''.
===General===
{{Main|Placental mesenchymal dysplasia}}
*Very rare ~ 70 reported cases.<ref name=pmid16753607>{{Cite journal  | last1 = Pham | first1 = T. | last2 = Steele | first2 = J. | last3 = Stayboldt | first3 = C. | last4 = Chan | first4 = L. | last5 = Benirschke | first5 = K. | title = Placental mesenchymal dysplasia is associated with high rates of intrauterine growth restriction and fetal demise: A report of 11 new cases and a review of the literature. | journal = Am J Clin Pathol | volume = 126 | issue = 1 | pages = 67-78 | month = Jul | year = 2006 | doi = 10.1309/RV45-HRD5-3YQ2-YFTP | PMID = 16753607 }}</ref>
*Etiology unknown.
 
Associations:<ref name=pmid16753607/>
*[[IUGR]] ~ 50% of cases.
*Fetal demise ~ 40-45% of cases.
*[[Beckwith-Wiedemann syndrome]].
 
===Gross===
Features:<ref name=pmid23266781>{{Cite journal  | last1 = Rohilla | first1 = M. | last2 = Siwatch | first2 = S. | last3 = Jain | first3 = V. | last4 = Nijhawan | first4 = R. | title = Placentomegaly and placental mesenchymal dysplasia. | journal = BMJ Case Rep | volume = 2012 | issue =  | pages =  | month =  | year = 2012 | doi = 10.1136/bcr-2012-007777 | PMID = 23266781 }}</ref>
*[[Placentomegaly]].
*Grape-like vesicles.
 
DDx - gross:
*[[Partial hydatidiform mole]].
 
Image:
*[http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3094260/figure/F3/ PMD (nih.gov)].<ref name=pmid21513565/>
===Microscopic===
Features:<ref name=pmid21513565>{{Cite journal  | last1 = Umazume | first1 = T. | last2 = Kataoka | first2 = S. | last3 = Kamamuta | first3 = K. | last4 = Tanuma | first4 = F. | last5 = Sumie | first5 = A. | last6 = Shirogane | first6 = T. | last7 = Kudou | first7 = T. | last8 = Ikeda | first8 = H. | title = Placental mesenchymal dysplasia, a case of intrauterine sudden death of fetus with rupture of cirsoid periumbilical chorionic vessels. | journal = Diagn Pathol | volume = 6 | issue =  | pages = 38 | month =  | year = 2011 | doi = 10.1186/1746-1596-6-38 | PMID = 21513565 }}</ref>
*Stem villi with edema (hydropic changes) and few blood vessels.
*Paucivascular (few blood vessels) or avascular (terminal) villi.
 
Note:
*Stem villi = large villi with a fibrotic core and (fetal) arteries and veins.<ref name=pmid9260835>{{Cite journal  | last1 = Demir | first1 = R. | last2 = Kosanke | first2 = G. | last3 = Kohnen | first3 = G. | last4 = Kertschanska | first4 = S. | last5 = Kaufmann | first5 = P. | title = Classification of human placental stem villi: review of structural and functional aspects. | journal = Microsc Res Tech | volume = 38 | issue = 1-2 | pages = 29-41 | month =  | year =  | doi = 10.1002/(SICI)1097-0029(19970701/15)38:1/229::AID-JEMT53.0.CO;2-P | PMID = 9260835 }}</ref>
 
Image:
*[http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3094260/figure/F5/ PMD (nih.gov)].<ref name=pmid21513565/>


=Placental cysts and pseudocysts=
=Placental cysts and pseudocysts=
Michael
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