Definition/General
Introduction:
Succenturiate lobe is characterized by accessory placental lobe separate from main placenta
It is connected by blood vessels running through membranes
It represents developmental variant
It carries risk of retained products.
Origin:
Results from secondary implantation of blastocyst
Uneven trophoblastic development
Persistence of secondary placental tissue
Developmental anomaly
Geographic separation during development.
Classification:
Classified by size: Small vs large accessory lobe
By number: Single vs multiple lobes
By connection: Vascular vs membranous
Complete vs incomplete.
Epidemiology:
Incidence approximately 0.5-3% of pregnancies
More common with IVF pregnancies
Higher risk of complications
Often undiagnosed prenatally.
Clinical Features
Presentation:
Retained placental tissue (most serious complication)
Postpartum hemorrhage
Vasa previa (connecting vessels)
Preterm rupture of membranes
Antepartum bleeding.
Symptoms:
Postpartum bleeding
Incomplete placental delivery
Signs of retained products
Secondary infection
Delayed involution
Abnormal lochia.
Risk Factors:
In vitro fertilization
Advanced maternal age
Multiple pregnancy
Previous uterine surgery
Uterine abnormalities
Implantation disorders.
Screening:
Careful placental examination at delivery
Vessel inspection at membrane edge
Ultrasound (limited sensitivity)
Completeness assessment.
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Gross Description
Appearance:
Separate placental lobe distinct from main placenta
Connecting blood vessels visible in membranes
Well-formed placental tissue
Variable size
Geographic separation.
Characteristics:
Complete placental structure in accessory lobe
Fetal and maternal surfaces identifiable
Umbilical vessels extending to lobe
Normal placental architecture.
Size Location:
Size ranges from few centimeters to large lobes
Located separate from main placenta
Variable distance apart
Connected by vessels
Any uterine location.
Multifocality:
Usually single accessory lobe
May have multiple lobes
Different sizes
Various locations
Independent blood supply.
Microscopic Description
Histological Features:
Normal placental histology
Terminal villi with normal architecture
Chorionic plate present
Basal plate with decidua
Normal vessel pattern.
Cellular Characteristics:
Normal trophoblast
Villous stromal cells
Fetal capillaries
Syncytiotrophoblast
Cytotrophoblast
Hofbauer cells.
Architectural Patterns:
Normal villous branching
Appropriate maturation
Terminal villous development
Normal vascular pattern
Decidual interface.
Grading Criteria:
Based on completeness of placental structure
Maturation assessment
Vascular integrity
Size relative to main placenta.
Immunohistochemistry
Positive Markers:
Normal placental markers
hCG (syncytiotrophoblast)
hPL (placental lactogen)
CD34 (fetal vessels)
Cytokeratin (trophoblast).
Negative Markers:
Pathological markers typically absent
Inflammatory markers (unless infected)
Malformation markers.
Diagnostic Utility:
Confirms normal placental tissue
Rules out pathology
Demonstrates normal function
Vascular assessment.
Molecular Subtypes:
Not applicable for routine classification.
Molecular/Genetic
Genetic Mutations:
Usually normal genetic composition
Developmental anomaly
No specific mutations
Same genetics as main placenta.
Molecular Markers:
Normal placental function markers
Appropriate hormone production
Normal growth factors
Vascular markers present.
Prognostic Significance:
Risk of retained products
Postpartum complications
Vasa previa risk
Good outcomes if recognized.
Therapeutic Targets:
Complete delivery essential
Careful examination
Manual removal if retained
Prophylactic measures.
Differential Diagnosis
Similar Entities:
Bipartite placenta (two equal lobes)
Multilobed placenta
Placental fragments
Cotyledon variations
Placental cysts.
Distinguishing Features:
Succenturiate: Unequal lobe sizes
Succenturiate: Connecting vessels
Bipartite: Equal-sized lobes
Fragments: Incomplete structure.
Diagnostic Challenges:
Recognition at delivery
Completeness assessment
Vessel identification
Prenatal diagnosis difficult.
Rare Variants:
Multiple succenturiate lobes
Large accessory lobe
Vasa previa association
Combined anomalies.
Sample Pathology Report
Template Format
Sample Pathology Report
Complete Report: This is an example of how the final pathology report should be structured for this condition.
Specimen Information
Placenta with succenturiate lobe measuring [size] connected by vessels through membranes
Diagnosis
Succenturiate Lobe (Accessory Placental Lobe)
Classification
Classification: [Single/Multiple] succenturiate lobe(s) with [complete/incomplete] delivery
Morphological Features
Shows well-formed accessory placental lobe connected to main placenta by blood vessels
Histological Features
Accessory lobe shows normal placental histology with appropriate maturation
Completeness Assessment
Placental delivery: [Complete/Incomplete], Risk of retained products: [Low/High]
Clinical Significance
Risk of postpartum complications including hemorrhage and retained products
Final Diagnosis
Succenturiate Lobe with [completeness status] and [risk level] for complications