My study notes for all pathologists

1. FLASHPATH
H a z e m A l i

2. PLACENTA
GROSSING
H a z e m A l i

3. INDICATIONS
Maternal conditions Placental conditions Fetal conditions
Hypertension
Will be discussed later
Stillbirth
Diabetes Prematurity
Immuno-compromised
“drug abuser”
Growth retardation
Abnormal bleeding Twin pregnancy
History of previous abortion Congenital anomalies
Fever, infectoins Low APGAR score
Fever, infections
If normal placenta, normal fetus, and normal mother  No need to examine plac

4. BEFORE WE START
• Records “request form”
– Case history / medical & surgical records
• The obstetric history is very important
– Type of specimen / operation
– If special tests are required
• Microbiology – molecular studies – ……
– Clinician name and telephone

5. BEFORE WE START
• Container
– Intact (sealed) or not
– Labelled or not
• patient name – type of specimen – clinician name – date
• Matched with the data on request form or not
– Fixed specimens or not
• Also type of fixation
• Many institutes prefer to examine the placenta freshly
– Specimen identification
• Whole organ – large parts – small fragments
• Matched with the data on request form / container’s label or not

6. SINGLE
GESTATION

7. UMBILICAL CORD
Measurements
• Length
– Does the cord received totally or just a segment?
• Short cord (< 35 cm for full term) can’t be diagnosed without receiving the total cord
• Long cord (> 70 cm for full term) can be diagnosed with received segment if it’s long
enough
• Diameter
– Measure the maximal and minimal diameters
• Thin cord = < 1 cm (full term)
• Always correlate with the gestational age “tables/charts”

8. UMBILICAL CORD
Coiling index:
• Total number of coils
Total length of the cord
• Normal: 0.2 (+/- 0.1)
– One – three coils / 10 cm long
– Average: 1 coil / 5 cm long
• Hyper-coiling: index > 0.3
• Hypo-coiling: index < 0.1
Hypo-coilingvshyper-coiling

9. UMBILICAL CORD
Color
• Normal:
– White – tan
• Abnormal:
– Dark Green  meconium
– Opaque , Yellowish - gray  infection
– Dark Red – Brown  hematomas
normalmeconiumhematoma

10. UMBILICAL CORD
Insertion
• Normal:
– Central / mildly eccentric
– Measure the distance to nearest edge
• Marginal insertion:
– Also called “battledore”
– Markedly eccentric
• 2 cm or less from the edge of the disc
– Not into the membranes
normalmarginal

11. UMBILICAL CORD
Insertion
• Membranous
– Also called “velamentous”
– Inserted into the fetal membranes
– Not into the disc
– Umbilical vessels branches within the membranes
• Measure the longest vessel
• Search for vessels tear, hemorrhage or thrombus
• Furcate
– Inserted into the placental disc
– Umbilical vessels branches before reaching the disc
• Measure the distance (branching point – insertion point)
• Search for vessels tear, hemorrhage or thrombus
velamentousfurcate

12. UMBILICAL CORD
Vessels number
• Normal:
– Three (two arteries – one vein)
• Abnormal:
– Two vessels (single umbilical artery)
• Single umbilical artery  may indicate heart or kidney anomalies (examine them)
• Should be assessed at least 5 cm above the chorionic plate
– Due to the possibility of vessels fusion / anastomosis near the placenta
• In case of cord segments specimens
– Record the vessels number at both ends
normal
Single artery

13. UMBILICAL CORD
Other findings
• Knots
– True:
• Cord loop upon itself
• Released physically
• Causing vascular obstruction
– False:
• Area of tortuosity / redundancy of vessel
– vessel length > cord length
• Not released physically
• No vascular obstruction
• Record: number – size – appearance – distance from both cord ends
TrueknotFalseknot

14. UMBILICAL CORD
Other findings
• Strictures
– Extremely narrow segment
– Due to absence of Wharton jelly
– Causing vascular obstruction
• Hematomas
• Thrombosis
• Record: number – size – appearance – distance from both cord ends
stricturehematoma

15. UMBILICAL CORD
In summary
• Length • Color • Other
• Diameter • Coiling
• Insertion • Cut section
(vessel number)

16. UMBILICAL CORD
Submitted sections
• At least two cut sections
– One: from fetal end
– Other: 5 cm at least away from the placental insertion
• Plus section of any abnormality

17. FETAL MEMBRANES
Completeness
• Place your hand inside the membranes
• Spread your fingers out to check for completeness
• Incomplete membranes should be reported
– Stripped or ragged
• Measure the nearest distance between the placental
margin & the site of membrane rupture
– If zero  placenta previa
– If > zero  no placenta previa
During the vaginal
delivery of placenta (3rd
stage), the placenta is
delivered with the
membranes facing the
maternal surface of the
disc (not the fetal one)

18. FETAL MEMBRANE
Color
• Normal:
– Shiny and translucent
• Abnormal:
– Dark Green  meconium
– Opaque , Yellowish - gray infection
– Dark Red – Brown  hematomas
normal
meconium
infection

19. FETAL MEMBRANES
Insertion
• Normal:
– At placental edge
• Circummarginate insertion:
– Membranes inserted inside the chorionic plate
– Away from the placenta edge
– No firm ridge at site of insertion
• Membranes at insertion site are thin, smooth
• % of circumference involved should be recorded
circummarginate

20. FETAL MEMBRANES
Insertion
• Circumvallate insertion:
– Membranes inserted inside the chorionic plate
– Away from the placenta edge
– Firm ridge at site of insertion
• Membranes at insertion site are thick, folded
• % of circumference involved should be recorded
circumvallate

21. FETAL MEMBRANES
Other findings
• Nodules (amnion nodosum)
– Yellowish – tan
– Fetal surface of the disc
– Indicate oligohydramnios
• Amniotic bands
– Amnion strips wrap around fetal parts
– Causing necrosis, amputation, deformities
Amnionnodosum

22. FETAL MEMBRANES
In summary
• Insertion • Color • Other
findings
• Completeness

23. FETAL MEMBRANES
Submitted sections
• At least two cut sections (membrane roll)
• Plus section of any abnormality
• Membrane roll
– Cut a strip “ 3 cm wide ” of membrane
• From rupture site till insertion site
– Hold the strip with forceps
– Roll the membrane around the forceps
• With the amnion inward
– Cut section the formed roll

24. PLACENTAL DISC
Weight
• Trimmed: removed cord & membranes
• Fresh better than fixed
– As formalin fixation increase the weight by 10%
Measurements
• Three dimensions
Always correlate with the gestational age “tables/charts”

25. PLACENTAL DISC
Color / Orientation
• Fetal surface
– Covered by shiny, translucent membranes
• Fetal surface is light blue – pink
– Site of umbilical cord insertion
• Maternal surface:
– Dark red lobules “cotyledons”
• Abnormal colors (see fetal membranes)
FetalsurfaceMaternalsurface

26. PLACENTAL DISC
Shape
• Normal:
– Discoid, single
• Bi-lobate placenta:
– Formed of two lobes of equal size
– Attached to each other by fetal vessels & membrane (should be examined)
– May show membranous insertion of the cord
• Succenturiate placenta:
– Formed of main disc + one or more smaller “accessory” lobes
– Attached to each other by fetal vessels & membrane (should be examined)
– May show membranous insertion of the cord
Bi-lobatesuccenturiate

27. PLACENTAL DISC
Surfaces
• Fetal surface
– Abnormal color (hematomas, meconium, infections)
– Whitish nodules (amniotic nodosum, subchorionic fibrin)
– Cysts
– Tumors (chorangioma)
– Check chorionic vessels (tear, thrombus)
– Others
• Record: number – size – appearance – location
– Location: central or peripheral
AmnionnodosumSubchorionicfibrincyst

28. PLACENTAL DISC
Surfaces
• Fetal surface
– Remember that chorionic arteries are more superficial to the veins
– This is important especially when checking for vascular anastomosis in twin
placenta (see later)
Hint:
• The peripheral veins (deoxygenated) runs
superficial to peripheral arteries
(oxygenated)
• The chorionic arteries (deoxygenated) runs
superficial to the chorionic veins
(oxygenated)

29. PLACENTAL DISC
Surfaces
• Maternal surface
– Intact or not (missed cotyledon / ragged surface)
• Indicate retained placenta or placenta accreta
– Abnormal color (hematomas – fibrin)
• Retro-placental hematoma
– Adherent
– Causing indentation of placental surface
• Extensive fibrin (maternal floor infarction)
– Extensive (thick), tan white basal plate
– Others
• Record: number – size – appearance – location
– Location: central or peripheral
Retro-placentalhematomaMaternalfloorinfarction

30. PLACENTAL DISC
Cut section (parenchyma)
• Normal:
– Spongy, red
• Abnormal:
– Firm, white areas
• Infarction (old) – thrombus (old) – Perivillous fibrin deposition
– Firm, red areas
• Infarction (recent) – thrombus (recent) – Chorangiomas
– Other lesions
• Record: number – size – appearance – location
– Location: central or peripheral
infarctionthrombuschorangioma

31. PLACENTAL DISC
In summary
• Weight • Color/orientation • Shape • Other
findings
• Dimensions • Cut section • Surfaces

32. PLACENTAL DISC
Submitted sections
• Serial sectioning of the disc
– one cm intervals
• At least two full thickness sections
– Each section includes both maternal & fetal surfaces
– From the central area (close to cord insertion)
• To include fetal vessels
– If section is thick, divide into two halves (fetal – maternal sides)
• Plus sections from any abnormality

33. MULTIPLE
GESTATION

34. DEFINITIONS
• Mono = one
• Di = two
• Zygote = fertilized ovum
• Chorionic = placenta
• Amniotic = sac
So,
• Mono-zygotic = fertilization of one ovum by one sperm
• Di-zygotic = fertilization of two ova by two sperms
• Mono-amniotic = one sac
• Di-amniotic = two sacs
• Mono-chorionic = one placenta
• Di-chorionic = two placentas
Possibilities:
• One placenta, one sac
• One placenta, two sacs
• Two placentas, two sacs
Could be two placentas, one sac?
Bi-lobate placenta gives the picture of
two placentas with one sac

35. EARLY EMBRYOGENESIS
Pre-implantation:
• Fertilization
– The sperm meets the ovum
– Zygote formation
• Cleavage
– Repetitive division (two cells  four  eight  ….)
– Morula formation (32 cells)
Peri-implantation:
• Blastocyst formation / cellular differentiation
– Morula acquire a cavity (blastocoel)
– Outer cellular shell  trophoblasts (placenta)
– Inner cell mass  embryoblasts (fetus)

36. EARLY EMBRYOGENESIS
Post-implantation:
• Embryoblasts differentiation (bi-laminar disc)
– Two layers (epiblasts – hypoblasts)
– Two cavities (amniotic cavity – primitive yolk sac)
• Primitive streak formation / gastrulation
– Midline transient structure (along caudal-cranial axis)
– Originate from the epiblast
– Establishes the bilateral similarity
– Initiates gastrulation (tri-laminar disc)
• Three germ layers (endoderm – ectoderm – mesoderm)

37. MONOZYGOTIC TWINS
• Also called “identical twins“
• The ovary release one ovum
• Fertilized by one sperm
• Forming one zygote
– Which undergo splitting
– Fate is dependent on splitting time (four scenarios)
• Too early splitting (couple days post fertilization = pre-implantation)
• Early splitting (during 1st week post fertilization = peri-implantation)
• Late splitting (during 2nd week post fertilization = post-implantation)
• Too late splitting (after 2nd week post fertilization = post-primitive streak formation)

38. MONOZYGOTIC TWINS
• Too early splitting ( < 3 days post ovulation)
– Splitting occurs at early zygote cleavage
– Forming two blastocysts
• Each implants separately
• Having two placentas
• Having two sacs
Di-amniotic, Di-chorionic

39. MONOZYGOTIC TWINS
• Early splitting ( 3 – 8 days post ovulation)
– A single blastocyst is formed
– Splitting occurs at inner cell mass “embryoblast”
– Forming two embryoblasts, covered by single trophoblast shell
• Having one placenta
• Having two sacs
Di-amniotic, Mono-chorionic

40. MONOZYGOTIC TWINS
• Late splitting ( 8 – 13 days post ovulation)
– A single blastocyst is formed, with a single inner cell mass “embryoblast”
– Splitting occurs at bi-laminar disc / before primitive streak formation
– Forming two fetuses, within single amniotic cavity, covered by single trophoblast
shell
• Having one placenta
• Having one sac
Mono-amniotic, Mono-chorionic

41. MONOZYGOTIC TWINS
• Too late splitting ( > 13 days post ovulation)
– A single blastocyst is formed, with a single inner cell mass “embryoblast”
– Splitting occurs at bi-laminar disc / during primitive streak formation
– Due to incomplete “partial” splitting of the primitive streak
– Forming two “inseparate” fetuses, within single amniotic cavity, covered by single
trophoblast shell
• Having one placenta
• Having one sac
• Conjoined twin
Mono-amniotic, Mono-chorionic, Conjoined

42. DIZYGOTIC TWINS
• Also called fraternal “non-identical“ twins
• The ovary released two ova
• Fertilized by two sperms
• Resulting in two zygotes
– Each implants separately
– having two placentas
– having two sac
Di-amniotic, Di-chorionic

43. EXAMINATION
• For any twin placenta, you should comment on:
• Plus the ordinary placental examination (see single gestation)
Umbilical cord
• Number
& attachment
• Identification
Placental disc
• Number (chorionicity)
• Zygosity (if applicable)
• Vascular equator
• Vascular anastomosis
Fetal membranes (especially fused
placental)
• Site of rupture
• Dividing membrane (chorionicity)

44. UMBILICAL CORD
Number
• Two cords should be seen
Attachment
• To single (fused) disc
• To separate (two) discs
Identification
• Using cord clamp (by clinician)
• To determine birth order
– 1st delivered neonate  designate its cord by one clamp
– 2nd delivered neonate  designate its cord by two clamps
• You should comment on presence/absence of clamps and the number per each cord
– If absent, designate the specimen by yourself

45. PLACENTAL DISC
Number (chorionicity)
• Two (separate)
– Di-chorionic, Di-amniotic
• Single (fused)
– Mono-chorionic, Mono-amniotic
– Mono-chorionic, Di-amniotic
– Di-chorionic, Di-amniotic (could be fused placenta)
• In this case, differentiated from mono-chorionic by characters of
dividing membrane
Zygosity:
• Mono-chorionic = Mono-zygotic
• Di-chorionic = either mono- or di-zygotic

46. PLACENTAL DISC
Vascular equator
• In separate twin placentas, It’s easily to record measurements of each placenta
separately
• But in fused twin placenta, it’s difficult to determine whose placental mass is whose
• Especially that the dividing membrane does not necessarily divide the fused placenta
equally
• So we search for the “vascular equator”, that it can tell us a rough estimate of the %
of each territory to the total placental mass
– E.g. the total placenta weighed …. gm, the proportion of each twin A and twin B placentas
is …. % and ….. % respectively

47. PLACENTAL DISC
Vascular equator
• Technique:
– Trim the dividing membrane
• To fully expose the fetal surface, especially at the fusion point
– Follow the chorionic vessels on fetal surface on both sides
• Follow the vessels arising from each umbilical cord
– The chorionic vessels meet/end at an imaginary line
• This is the vascular equator
• Better to be examined freshly
• Better to be examined with dye injection
– see vascular anastomosis

48. PLACENTAL DISC
Vascular anastomosis
• Incidence
– mainly Mono-chorionic
– Rare in di-chorionic (fused)
• Types
– Arterial-to-venous (A-V)
– Arterial-to-arterial (A-A)
– Venous-to-venous (V-V)
• Remember that chorionic arteries are more superficial to the veins (see single
gestation)
• Asymptomatic
• Compensate the effect of A-V shunts (protective against TTTS)
• Significant clinically
• Associated with twin-twin transfusion syndrome (TTTS)

49. PLACENTAL DISC
• Technique
– Naked eye:
• Anastomosis is difficult to be discovered (need experience)
– Dye injection:
• Anastomosis is easily discovered
• Inject umbilical vessels on each cord with different dyes
– Four dyes (twin A artery / vein – twin B artery / vein)
• Look for any dye (vessel) cross to the other side
• Record:
– Number of anastomosis
– Type of anastomosis
• In mono-chorionic placentas without TTTS
– Usually shows multiple anastomoses
• In mono-chorionic placentas with TTTS
– Almost always have a single (A-V) anastomosis

50. PLACENTAL DISC
• Placental findings suspicious for twin-twin transfusion syndrome
– Any case of mono-chorionic placenta
– If one side of placenta appears more congested (dark red), firmer than the other side
– Presence of A-V anastomosis (very important)

51. FETAL MEMBRANES
Especially in single (fused) placenta
Site of rupture
• Two separate sites of rupture
• One common large site of rupture
Presence/absence of dividing membrane
• Seen in:
– Adherent sacs (di-amniotic, either mono- or di-chorionic)
• Not seen in
– Single sac (mono-amniotic, mono-chorionic)
– Separate sacs (di-amniotic, di-chorionic separate placentas)

52. DIVIDING MEMBRANE
Gross features
Di-chorionic (fused) Mono-chorionic
- Thicker, opaque
- Difficult to peel off
- Tri-laminar
- Two outer amnions
- One central chorion
- Thick site of insertion
(ridge)
- Vascular anastomosis is
rare
- Thin, translucent
- Easy to peel off
- Bi-laminar
- Two opposing
amnions
- Smooth site of insertion
(no ridge)
- Vascular anastomosis is
common

53. IN SUMMARY
Di-chorionic, Di-
amniotic (separate)
Di-chorionic, Di-
amniotic (fused)
Mono-chorionic, Di-
amniotic
Mono-chorionic,
Mono-amniotic
Two umbilical cords Two umbilical cords Two umbilical cords Two umbilical cords
Two “separate” amniotic
sacs
Two “adherent”
amniotic sacs
Two “adherent”
amniotic sacs
Single amniotic sac
Two “Separate”
placentas
“Fused” placentas Single placenta Single placenta
Two amnions + Two
chorions
Two amnions + Two
“fused” chorions
Two amnions + One
chorion
One amnion + One
chorion
No dividing membrane Dividing membrane
• Thick
• Opaque
• Tri-laminar
Dividing membrane
• Thin
• Translucent
• Bi-laminar
No dividing membrane
No fetal vessels
anastomosis
Rare fetal vessels
anastomosis
Common fetal vessels
anastomosis
Common fetal vessels
anastomosis
Mono- or Di-zygotic Mono- or Di-zygotic Always Mono-zygotic Always Mono-zygotic

54. SUBMITTED SECTIONS
• Sections from each:
– Umbilical cord
– Fetal membranes
– Placental disc
• Plus sections from dividing membrane:
– Membrane roll section (free end)
– T-zone section (site of attachment to the disc)
• Plus sections from any abnormality
As single gestation
Designation is so important
e.g. twin 1,2 – twin A,B

55. THANK YOU
H a z e m A l i