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    Placenta multiple

    Background

    The placenta is usually examined in cases of stillbirth and intrauterine fetal death. It may also be examined in the event of maternal, obstetric or paediatric difficulties/abnormalities during the pregnancy or at the time of delivery.1-6 A protocol for referring placentas for histopathology should be established in consultation with obstetric specialists.2 Lists of possible clinical indications are provided in the referenced guidelines below.2,3

    This protocol has been updated to reflect macroscopic protocols agreed following the Amsterdam Placental workshop group consensus statement on sampling and definition of placental lesions.4

    Videos on this page have been donated by Drs Amanda Charlton and Susan Arbuckle. They provide useful visual demonstrations of swabbing, examining and dissecting placenta specimens. However users should refer to the protocol text and dictation templates for a comprehensive understanding of the information required in handling placenta specimens.


    Record the patient identifying information and any clinical information supplied together with the specimen description as designated on the container. See overview page for more detail on identification principles.

    Placentas should be accompanied by a birth summary with as much relevant clinical history as possible.

    Information provided should include date of delivery, gestational age, plurality, cord length including any missing portions, birth weight, relevant clinical history and ultrasound results as well as the clinical indication for pathological examination.2

    Note the receipt of fresh tissue and requests for special studies. It is recommended that all placentas are transferred fresh to pathology due to the possible microbiological, cytogenetic and metabolic studies that may be required.2

    • No
      • Non-routine fixation (not formalin), describe.
    • Yes
      • Yes
        • Special studies required, describe
        • Ensure samples are taken prior to fixation.
        • MicrobiologIical including viral studies
        • Cytogenetics
    Condition1,5,6 Microbiology Cytogenetics Histopathology
    All pre-term births <37 weeks* Yes As needed (PRN) Yes
    Prolonged rupture of membranes Yes No Yes
    Suspected maternal/fetal bacterial or viral infection Yes No Yes
    Intrauterine growth restriction (IUGR) No** No Yes
    Perinatal death Yes Yes Yes
    Pre-eclampsia No No Yes
    Twins PRN PRN Yes
    Placenta praevia No No Yes
    *UK guidelines suggest that pathological examination of placenta is desirable <37/40 but essential <30/40.1
    **UK guidelines recommend microbiological investigations for IUGR.1

    For a detailed outline of maternal, fetal and neonatal indications for placental histological examination see Attachment 1 of the NSW guideline.2

    See general information for more detail on specimen handling procedures.

    Inspect the specimen and dictate a macroscopic description.


    External Inspection

    Orientate and identify the anatomical features of the specimen.

    Photograph the intact specimen if required.

    Describe the following features of the specimen:

    Procedure/specimen type

    Describe as stated by the clinician.

    Placenta

    • Single see separate protocol
    • Multiple gestation

    Identifying clamps

    • Absent
      • Describe each placenta as A, B etc
    • Present
      • Describe as identified for birth order 1, 2 etc

    Identification for twins: one clamp = twin 1; two clamps = twin 2

    Follow the clinician’s labelling of Twin I and Twin 2 that corresponds with birth order. If not specified, label placentas “A” and “B” (do not use 1 and 2) and describe each separately.

    Placentation

    • Not fused
      • Dichorionic diamnionitic (DCDA) no dividing membranes
    • Fused
      • Dichorionic diamnionitic (DCDA)
      • Monochorionic monoamniotic (MCMA)
      • Monochorionic diamnionitic (MCDA)
        • Dye injection used (fresh specimen only)
      • Identify vascular equator
        • Specify relative proportion in each territory (%)
      • Vascular anastomoses
        • Yes
        • No

    Look for a dividing membrane attached to the placental surface present in a dichorionic placenta or a mobile dividing membrane present in a monochorionic placenta.1

    Triplet placentas are processed in a similar manner but there are three umbilical cords and dividing membranes to be observed.

    Anatomical components included (more than one may apply) and specimen dimensions (mm)

    Describe and measure the anatomical components present.

    For each placenta:

    Membrane description

    Describe the placental membranes:

    Membrane completeness

    • Complete with single point of rupture
      • Closest distance to edge of placenta (mm)
    • Incomplete (stripped or ragged)

    Membrane appearance

    • Opacity (translucent/opaque)
    • Colour/texture (brown/green/slimy)

    Membrane insertion

    • Marginal (normal situation)
    • Circummarginate (% of circumference involved)
    • Circumvallate (% of circumference involved)

    Other findings in membranes

    • Plaques/nodules/any vessels

    Umbilical cord description

    Describe the umbilical cord:

    • Length
    • Diameter, minimum and maximum (mm)1,3,7
    • Number of vessels present at both ends

    Measure the maximum cord diameter at a representative point excluding false knots. Ensure the thin, flattened parts of the cord are also measured as these are areas of abnormality.

    Insertion point

    • Central
    • Eccentric
    • Marginal
    • Velamentous
      • Measure the maximum length (mm) of a vessel within the membrane and describe (e.g. presence of haemorrhage that might suggest rupture)
    • Distance from placental edge (mm)

    Colour

    • Normal
    • Abnormal
      • Describe colour and area involved

    Coiling index number9

    Count the total number of coils present in the full length of the umbilical cord and report as coils per cm. However, irregular areas of under or overcoiling must also be described.

    • Number per total length (mm) of cord
      • If there are localised segments with overcoiling, these should be recorded also, e.g. total of 20 coils per 750mm with hypercoiled section of 5 coils per 50mm.​

    Umbilical cord abnormalities

    Other findings (knot, stricture, thrombosis, haematoma or oedema)

    • No
    • Yes
      • Describe appearance, size and location
      • If cord is tethered to fetal surface, record the length of tethering (mm)

    Placental disc description

    Describe the following features of the placental disc:

    Placental shape

    • Oval
    • Round
    • Irregular
    • Bilobed
    • Accessory lobe
      • Measure in three dimensions (mm)
    • Fragmented

    Iatrogenic procedures

    • No
    • Yes, describe procedure undertaken and /or describe its macroscopic appearance and location e.g umbilical/vessel ablations

    Fetal surface

    • Normal
    • Abnormal, describe focal lesion(s) including abnormalities of chorionic vessels
      • Number
      • Appearance e.g. thrombus,white, firm, non-compressible
      • Configuration e.g. solid, cystic, blood clot
      • Circumscription e.g. well-demarcated
      • Colour e.g. white, marbling, haemorrhagic
      • Texture e.g. firm, soft, gelatinous
      • Overall involvement of placental disc (%)

    Vessels on the chorionic surface should be described where abnormal including thrombi and aneurysmal dilatation.

    Maternal surface

    • Complete
    • Incomplete
    • Ragged and unable to be assessed

    Other findings

    Other findings (fibrin, haematomas, indentations)

    • Number of lesions
    • Specify lesion and describe:
      • Size (% involvement)
      • Location (central 2/3 or peripheral 1/3)

    Specimen weight (g)

    • Placental weight trimmed of cord and membranes1,4-10

    Specimen size (mm)

    • Maximum dimension x perpendicular diameter4
    • Minimum and maximum thickness of placental disc1,4-7

    Dissection

    A membrane roll is made from the site of rupture to the margin of the disc. This can be done by grasping the edge with fine forceps and rolling toward the disc. The point of rupture will then be central in the roll and the membrane insertion at the outside with the amnion facing inwards.

    Section areas of abnormality as well as areas close to the insertion point and cut end, noting the number of vessels.

    After description and block taking from umbilical cord and membranes, divide fused placentas along the vascular equator. Weigh each portion separately.

    • DCDA separate placentas -gently pull apart
    • DCDA fused placentas –peel off the amniotic membranes from both sides, leaving part of the middle fused thick chorionic membrane

    Inject dye into the vessels of all monochorionic twin placentas for assessment of anastomoses (MCMA + MCDA). Use four colours and inject into umbilical vessels near base of placental disc using thin catheters. Leave to fix overnight.

    • MCDA fused placentas –separate the two amnions on either side of the single chorion
    • MCMA –there is no dividing membrane in fused placenta, peel away the entire amnion from the chorionic surface
    Section areas of abnormality as well as areas close to the insertion point and cut end, noting the number of vessels.

    Minimum sections to include are a transverse section from the fetal end and a section 5 cm from the insertion site. The number of umbilical vessels should be noted and any macroscopic cord abnormalities should be sampled.4

    Serially section the placental disc.

    After dissection the specimen may require longer fixation in larger quantity of formalin.


    Internal Inspection

    Describe the cut surface appearance including the following items:

    Parenchyma

    • Normal
    • Abnormal, describe focal lesion(s)
      • Twin territory involved (1/2 or A/B) using cord vasculature
      • Number
      • Location (central 2/3 or peripheral 1/3; maternal surface, fetal surface or intraparenchymal)
      • Appearance
      • Configuration e.g. solid, cystic, blood clot
      • Circumscription e.g. well-demarcated
      • Colour e.g. white, marbling, haemorrhagic
      • Texture e.g. firm, soft, gelatinous
      • Overall involvement of placental disc (% of volume volume)

    Lesion location (if applicable)

    • Central 2/3
    • Peripheral 1/3

    Photograph the dissected specimen if required.

    Note any photographs taken, diagrams recorded and markings used for identification.


    Processing

    Dissect the specimen further and submit sections for processing.

    For each placenta, submit representative sections of:

    • Umbilical cord -two sections (one from the cut end and one 5 cm from point of insertion into the disc) 10
    • Membrane roll -a minimum of one section(note that the rupture site should be included in a membrane roll)
    • Umbilical cord insertion site -one full thickness section of disc parenchyma close to umbilical cord insertion site to include fetal surface vessels
    • Parenchyma -two additional blocks (minimum) from the placenta parenchyma plus an optional shave slice taken parallel to the maternal surface
    • Marginal block including fetal, maternal and membrane insertion site
    • Abnormal areas -one section of each and identify what is represented and the location (central 2/3 or peripheral 1/3) in the block key
    • Dividing membrane(s) -one representative section in a membrane roll

    Record details of each cassette.

    A block key similar to the one provided may be useful.

    Block allocation key

    Twin 1
    Cassette id
    Site
    No. of pieces
    A
    Umbilical cord; fetal cut end and 5 cm from placental insertion
     
    B
    Membrane roll
     
    C
    Disc parenchyma adjacent to umbilical cord insertion site, full thickness section
     
    D-E
    Placental disc parenchyma
     
    F
    Marginal placenta or incude in membrane roll
     
    G-H
    Abnormalities (e.g. infarction, thrombus) one section of each
     
    I+
    Dividing membranes in a membrane roll
     
    Twin 2 etc. Repeat A-H
     

    Acknowledgements

    Prof Jane Dahlstrom, Dr Amanda Charlton and Dr Susan Arbuckle for their contributions in reviewing and editing this protocol.


    References

    1. Cox P, Evans C. Tissue pathway for histopathological examination of the placenta, London: The Royal College of Pathologists; 2011.
    2. Flenady V, King J, Charles A, Gardener G, Ellwood D, Day K, et al for the Perinatal Society of Australia and New Zealand (PSANZ) Perinatal Mortality Group. PSANZ Clinical Practice Guideline for Perinatal Mortality. Version 2.3. Brisbane, 2009
    3. Khong TY, Mooney EE, Ariel I, et al. Sampling and Definitions of Placental Lesions: Amsterdam Placental Workshop Group Consensus Statement. Arch Pathol Lab Med. 2016;140(7):698-713.
    4. Hargitai B, Marton T, Cox PM. Best practice no. 178 : Examination of the human placenta. J of Clin Path. 2004;57(8):785-92.
    5. Langston C, Kaplan C, Macpherson T, Manci E, Peevy K, Clark B, et al. Practice guideline for examination of the placenta: developed by the Placental Pathology Practice Guideline Development Task Force of the College of American Pathologists. Arch Pathol Lab Med. 1997;121(5):449-76.
    6. Lester SC (ed). Manual of Surgical Pathology, Saunders Elsevier, Philadelphia, 2010.
    7. Proctor LK, Fitzgerald B, Whittle WL, Mokhtari N, Lee E, Machin G, et al. Umbilical cord diameter percentile curves and their correlation to birth weight and placental pathology. Placenta. 2013;34(1):62-6.
    8. van Diik CC, Franx A, de Laat MW, Bruinse HW, Visser GH, Nikkels PG. The umbilical coiling index in normal pregnancy. J Matern Fetal Neonatal Med. 2002;11(4):280-3.
    9. Thompson J, Irgens L, Skjaerven R, Rasmussen S. Placenta weight percentile curves for singleton deliveries. BJOG 2007;114:715-20.

    Jump To

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      Placenta cord dissection

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      Placenta disc dissection

      Placenta disc dissection

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      Placenta block taking

      Placenta block taking

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      25-Mar-2019
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