Definition/General
Introduction:
Circumvallate placenta is characterized by folding of fetal membranes at placental margin
It shows ring-shaped ridge on fetal surface
It represents extrachorial placentation
It results in reduced functional surface area.
Origin:
Results from discrepancy between chorionic and basal plate growth
Inadequate decidual growth
Early membrane rupture with reattachment
Abnormal implantation site
Uterine constraint
Leads to membrane folding.
Classification:
Classified as extrachorial placenta
Complete: Entire margin involved
Partial: Portion of margin affected
Mild vs severe based on degree of folding
Distinguished from circummarginate.
Epidemiology:
Incidence approximately 1-2% of pregnancies
More common with oligohydramnios
Associated with preterm delivery
Higher incidence in multiple pregnancies
Often underdiagnosed.
Clinical Features
Presentation:
Antepartum bleeding (most common)
Preterm labor
Premature rupture of membranes
Intrauterine growth restriction
Oligohydramnios
Placental abruption.
Symptoms:
Vaginal bleeding in second/third trimester
Uterine contractions
Fluid leakage (PROM)
Decreased fetal movements
Abdominal pain
Measuring small for dates.
Risk Factors:
Advanced maternal age
Previous circumvallate placenta
Uterine abnormalities
Oligohydramnios
Multiple pregnancy
Chronic hypertension
Smoking.
Screening:
Ultrasound examination
Fetal growth assessment
Amniotic fluid volume measurement
Placental morphology evaluation
Doppler studies
Enhanced surveillance.
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Gross Description
Appearance:
Raised ring-shaped ridge on fetal surface
Grayish-white fibrous ring
Folded membranes creating double layer
Reduced apparent placental size
Central depression
Hemorrhage may be present at margins.
Characteristics:
Circumferential ridge on fetal surface
Membrane folding inward
Fibrous appearance of ridge
May have old hemorrhage
Intact membranes centrally
Peripheral membrane doubling.
Size Location:
Entire placental margin (complete) or portion (partial)
Ridge located inward from true margin
Concentric pattern
Variable depth of folding
Reduced functional diameter.
Multifocality:
Usually circumferential involvement
May be focal (partial type)
Uniform ridge formation
No skip areas in complete type
Symmetric pattern typically.
Microscopic Description
Histological Features:
Folded chorioamniotic membranes
Fibrous connective tissue in ridge
Hemosiderin deposition
Chronic inflammation
Membrane thickening
Decidual remnants in fold.
Cellular Characteristics:
Fibroblastic proliferation
Hemosiderin-laden macrophages
Chronic inflammatory cells
Thickened amnion
Decidual cells (variable)
Vessel proliferation.
Architectural Patterns:
Double membrane layer
Infolding pattern
Fibrous tissue proliferation
Loss of normal membrane structure
Vascular compromise
Hemorrhage organization.
Grading Criteria:
Mild: Shallow folding, minimal fibrous tissue
Moderate: Moderate folding with fibrous ridge
Severe: Deep folding, extensive fibrosis
Based on degree of membrane folding.
Immunohistochemistry
Positive Markers:
Smooth muscle actin (myofibroblasts)
CD68 (macrophages)
Factor VIII (endothelial cells)
Collagen IV (basement membrane)
Fibrin (if hemorrhage).
Negative Markers:
Cytokeratin (in fibrous areas)
hCG (trophoblast markers)
Inflammatory markers (acute)
Infectious organism stains.
Diagnostic Utility:
Confirms fibrous nature of ridge
Demonstrates chronic changes
Rules out inflammatory conditions
Assesses vascular changes
Characterizes tissue composition.
Molecular Subtypes:
Not applicable for routine classification
Associated conditions may require specific evaluation.
Molecular/Genetic
Genetic Mutations:
No specific genetic mutations identified
Developmental anomaly
May be associated with chromosomal abnormalities
Multifactorial inheritance possible.
Molecular Markers:
Growth factors (VEGF, PDGF)
Fibrosis markers (TGF-β)
Matrix metalloproteinases
Angiogenesis factors
Apoptosis markers.
Prognostic Significance:
Increased risk of pregnancy complications
Preterm delivery (40-50%)
Antepartum bleeding (25-30%)
Growth restriction
Perinatal mortality increased.
Therapeutic Targets:
Enhanced prenatal surveillance
Serial growth assessments
Timing of delivery optimization
Steroid administration for lung maturity
Close monitoring for complications.
Differential Diagnosis
Similar Entities:
Circummarginate placenta (no membrane folding)
Placental abruption (hemorrhage)
Marginal insertion abnormalities
Membrane cysts
Normal placental variants.
Distinguishing Features:
Circumvallate: Membrane folding present
Circumvallate: Fibrous ridge
Circummarginate: No membrane folding
Circummarginate: Flat transition
Abruption: Acute hemorrhage.
Diagnostic Challenges:
Distinguishing from circummarginate placenta
Recognition of membrane folding
Adequate examination of margins
Clinical correlation important.
Rare Variants:
Partial circumvallate
Severe with extensive fibrosis
Combined with other anomalies
Associated with cord abnormalities
Recurrent circumvallate.
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 showing circumferential ridge with membrane folding involving [complete/partial] margin
Diagnosis
Circumvallate Placenta
Classification
Classification: [Complete/Partial] circumvallate placenta, [severity] degree
Morphological Features
Shows raised fibrous ridge with membrane folding creating double layer at margins
Histological Features
Shows folded chorioamniotic membranes with fibrous connective tissue proliferation
Severity Assessment
Severity: [Mild/Moderate/Severe] based on degree of folding and fibrosis
Extent of Involvement
Involvement: [Percentage]% of placental margin with [uniform/variable] distribution
Clinical Correlation
Associated with increased risk of [complications]. Enhanced surveillance recommended.
Final Diagnosis
Circumvallate Placenta, [extent], [severity], with associated pregnancy complications