Definition/General
Introduction:
Maternal floor infarction (MFI) is characterized by excessive fibrin deposition at the basal plate
It involves obliteration of the uteroplacental interface
It results in impaired maternal-fetal exchange
It represents abnormal coagulation at the maternal floor.
Origin:
Results from abnormal fibrin deposition at uteroplacental interface
Complement activation may trigger process
Maternal thrombophilia predisposes
Decidual vasculopathy may initiate
Leads to functional placental insufficiency.
Classification:
Classified by extent of involvement: Focal vs extensive
By severity: Complete vs incomplete obliteration
By associated features: With/without villous changes
Pattern-based: Geographic vs patchy distribution.
Epidemiology:
Rare condition with incidence 0.5-1% of pregnancies
Associated with poor fetal outcomes
Recurrence rate approximately 20-25%
More common in pregnancies with maternal vascular disease.
Clinical Features
Presentation:
Severe intrauterine growth restriction
Stillbirth
Preterm delivery
Oligohydramnios
Non-reassuring fetal heart rate patterns
Placental abruption (some cases)
Maternal hypertension.
Symptoms:
Decreased fetal movements
Measuring small for gestational age
Reduced amniotic fluid
Abnormal fetal Doppler studies
Signs of chronic fetal compromise
Maternal symptoms usually absent.
Risk Factors:
Maternal thrombophilia
Chronic hypertension
Diabetes mellitus
Autoimmune disorders
Advanced maternal age
Previous pregnancy with MFI
Smoking during pregnancy.
Screening:
Fetal growth monitoring
Doppler studies of uterine and umbilical arteries
Amniotic fluid assessment
Non-stress testing
Thrombophilia workup
Maternal blood pressure monitoring.
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Gross Description
Appearance:
Maternal surface shows firm, white-gray areas
Loss of normal spongy texture
Geographic pattern of involvement
Cut surface reveals white, firm tissue at basal plate
Decreased placental weight may be present.
Characteristics:
Firm, rubbery consistency at maternal surface
White-gray discoloration
Loss of normal cotyledonary pattern
Smooth, firm maternal surface
May involve entire maternal floor
Well-demarcated lesions.
Size Location:
Involves basal plate region specifically
May affect focal areas or entire maternal floor
Geographic distribution
Thickness varies from few millimeters to centimeters
Maternal surface predominantly affected.
Multifocality:
May show multifocal involvement
Confluent areas common
Geographic pattern of distribution
Complete maternal floor involvement in severe cases
Skip lesions possible.
Microscopic Description
Histological Features:
Dense fibrin deposition at basal plate
Obliteration of intervillous space at maternal floor
Villous entrapment in fibrin matrix
Loss of normal uteroplacental interface
Decidual vessel thrombosis
Chronic decidual changes.
Cellular Characteristics:
Eosinophilic fibrin deposits
Entrapped anchoring villi
Loss of trophoblastic shell continuity
Decidual cell degeneration
Chronic inflammatory infiltrate (minimal)
Vessel wall thickening.
Architectural Patterns:
Complete basal plate obliteration
Loss of normal maternal-fetal interface
Fibrin lakes at maternal floor
Villous architecture distortion
Secondary villous changes
Intervillous circulation compromise.
Grading Criteria:
Based on extent of basal plate involvement
Focal MFI: <30% of basal plate
Extensive MFI: ≥30% of basal plate
Severity: Complete vs partial obliteration.
Immunohistochemistry
Positive Markers:
Fibrin (confirms fibrin nature of deposits)
Fibrinogen (precursor identification)
Complement components (C3, C4, C5b-9)
Factor VIII (vascular damage marker)
CD31 (endothelial assessment).
Negative Markers:
Inflammatory markers (CD3, CD20, CD68 minimal)
Smooth muscle actin (vessel integrity)
Trophoblast markers (CK7, hPL) in obliterated areas
Infectious organism stains.
Diagnostic Utility:
Fibrin stains confirm diagnosis
Quantifies extent of deposition
Assesses complement involvement
Rules out inflammatory conditions
Essential for accurate diagnosis.
Molecular Subtypes:
Thrombophilia-associated MFI
Complement-mediated MFI
Hypertension-associated MFI
Diabetes-associated forms
Idiopathic MFI.
Molecular/Genetic
Genetic Mutations:
Thrombophilia mutations (Factor V Leiden, Prothrombin mutation)
Complement system variants
MTHFR polymorphisms
Coagulation factor deficiencies
ACE gene polymorphisms.
Molecular Markers:
Coagulation studies
Complement activation markers
D-dimer levels
Fibrinogen levels
Antiphospholipid antibodies
Thrombophilia genetic testing.
Prognostic Significance:
Poor fetal outcomes
High risk of stillbirth
Severe growth restriction
Recurrence risk 20-25%
Associated with preterm delivery.
Therapeutic Targets:
Anticoagulation therapy
Low-dose aspirin prophylaxis
Enhanced fetal surveillance
Blood pressure control
Timing of delivery optimization
Thrombophilia management.
Differential Diagnosis
Similar Entities:
Massive perivillous fibrin deposition (perivillous location)
Placental infarction (villous necrosis)
Chronic abruption (retroplacental location)
Normal basal plate fibrin (minimal amount)
Decidual vasculopathy.
Distinguishing Features:
MFI: Basal plate location specifically
MFI: No villous necrosis
MPFD: Perivillous distribution
Infarction: Villous necrosis present
Abruption: Retroplacental hematoma
Normal: Minimal fibrin amount.
Diagnostic Challenges:
Distinguishing from normal basal plate fibrin
Quantifying extent of involvement
Adequate sampling of maternal surface
Correlation with clinical outcomes
Recognition of early changes.
Rare Variants:
MFI with villous infarction
Combined MFI and MPFD
Recurrent familial MFI
MFI with chronic abruption
Complement-mediated variants.
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 weighing [weight]g with firm white areas involving [percentage]% of maternal surface
Diagnosis
Maternal Floor Infarction
Classification
Classification: [Focal/Extensive] maternal floor infarction involving [percentage]% of basal plate
Histological Features
Shows dense fibrin deposition at basal plate with obliteration of uteroplacental interface
Extent Assessment
Maternal floor involvement: [percentage]% with [complete/partial] obliteration pattern
Special Stains
Fibrin stain: Positive at basal plate, confirming fibrin deposition
Villous Assessment
Overlying villi show [secondary changes/preservation] without frank infarction
Clinical Correlation
Findings correlate with [fetal growth restriction/adverse outcomes]. Impaired maternal-fetal exchange.
Final Diagnosis
Maternal Floor Infarction, [extent], with associated [clinical outcomes] and [recurrence risk]%