Definition/General
Introduction:
Placental percreta represents the most severe form of accreta spectrum disorders
The chorionic villi penetrate through the full thickness of the myometrium to reach the uterine serosa
It may extend into adjacent organs such as bladder or bowel
It occurs in 5-7% of accreta spectrum cases
It carries the highest maternal morbidity and mortality risk.
Origin:
Results from complete absence of decidua basalis in affected areas
Uncontrolled trophoblast invasion through entire myometrial thickness
Often associated with previous cesarean section scars
Defective uterine healing creates vulnerable areas
Abnormal angiogenesis facilitates deep invasion.
Classification:
Most severe of accreta spectrum: Grade 3 disorder
May be superficial percreta (just through serosa)
Deep percreta (into adjacent organs)
Focal or diffuse involvement
Classification by organ involvement.
Epidemiology:
Comprises 5-7% of accreta spectrum cases
Highest morbidity of accreta types
Maternal mortality: 9.5%
Hysterectomy rate: 90-100%
Massive transfusion required in 50% cases
ICU admission in 60% cases.
Clinical Features
Presentation:
Life-threatening hemorrhage
Hemodynamic shock
DIC (disseminated intravascular coagulation)
Multiorgan involvement
Bladder invasion (hematuria)
Bowel involvement (rare)
Emergency hysterectomy required.
Symptoms:
Catastrophic bleeding
Signs of shock
Abdominal distension
Hematuria (bladder involvement)
Decreased urine output
Respiratory distress
Altered consciousness.
Risk Factors:
Multiple prior cesareans (>3)
Placenta previa with prior cesarean
Advanced maternal age (>40)
Short interpregnancy interval
Smoking
Previous uterine procedures
In vitro fertilization.
Screening:
MRI is gold standard
T2 dark bands disruption
Bladder wall invasion
Focal bulging
Abnormal vascularity
Cystoscopy if bladder involvement suspected
Multidisciplinary team planning.
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Gross Description
Appearance:
Placental tissue penetrating through uterine serosa
Bladder wall may show invasion
Hemorrhagic, friable tissue
Complete loss of normal tissue planes
Vascular congestion and thrombosis.
Characteristics:
Serosal surface irregularity and invasion
Bladder wall thickening and nodularity
Placental villi visible on serosal surface
Extensive hemorrhage and necrosis
Fibrous tissue proliferation.
Size Location:
Most commonly anterior wall over cesarean scar
Bladder fundus frequently involved
May extend laterally to uterine vessels
Posterior percreta may involve bowel
Cervical involvement possible.
Multifocality:
Multiple perforation sites possible
Skip areas of involvement
Progressive extension during pregnancy
Associated with massive vascular proliferation.
Microscopic Description
Histological Features:
Chorionic villi and trophoblast through full myometrial thickness
Serosal invasion by extravillous trophoblast
Adjacent organ invasion (bladder, bowel)
Extensive vascular proliferation
Hemorrhage and necrosis.
Cellular Characteristics:
Extravillous trophoblast at serosal surface
Intermediate trophoblast invasion
Syncytiotrophoblast giant cells
Decidual cells completely absent
Inflammatory infiltrate.
Architectural Patterns:
Complete myometrial replacement by placental tissue
Serosal architecture disrupted
Normal tissue planes obliterated
Vascular malformation patterns
Foreign body reaction.
Grading Criteria:
Full-thickness invasion through myometrium
Serosal surface involvement
Depth of invasion into adjacent organs
Extent of surface involvement
Vascular invasion assessment.
Immunohistochemistry
Positive Markers:
Cytokeratin (trophoblast at serosa)
Mel-CAM (extravillous trophoblast)
Inhibin-α (trophoblast cells)
Beta-hCG (syncytiotrophoblast)
VEGF (angiogenesis)
CD31 (endothelial cells).
Negative Markers:
Smooth muscle actin (destroyed myometrium)
Desmin (muscle loss)
Caldesmon (smooth muscle)
Normal serosal markers disrupted.
Diagnostic Utility:
Confirms trophoblast invasion through serosa
Maps extent of invasion
Identifies vascular involvement
Distinguishes from other invasive processes
Guides surgical margins.
Molecular Subtypes:
Bladder-invasive percreta
Bowel-invasive percreta
Vessel-invasive percreta
Multiorgan percreta.
Molecular/Genetic
Genetic Mutations:
Severe PTEN downregulation
WNT pathway hyperactivation
Matrix metalloproteinase overexpression
Integrin abnormalities
E-cadherin loss.
Molecular Markers:
Markedly elevated MMP-2, MMP-9
Decreased TIMP expression
High VEGF levels
Abnormal integrin patterns
Loss of adhesion molecules.
Prognostic Significance:
Highest mortality risk (9.5%)
Hysterectomy nearly universal
Massive transfusion requirement
ICU care often needed
Long-term complications.
Therapeutic Targets:
Prophylactic balloon occlusion
Preoperative embolization
Multidisciplinary surgery
Hysterectomy with organ repair
Intensive care management.
Differential Diagnosis
Similar Entities:
Placental increta (partial invasion)
Adenomyosis (benign invasion)
Endometrial carcinoma (malignant invasion)
Choriocarcinoma (trophoblastic tumor)
Invasive mole.
Distinguishing Features:
Percreta: Full-thickness invasion
Serosal involvement
Adjacent organ invasion
Increta: Partial myometrial invasion
No serosal involvement
Carcinoma: Malignant cytology
Different invasion pattern.
Diagnostic Challenges:
Preoperative diagnosis critical
Extent assessment
Organ involvement mapping
Vascular anatomy
Surgical planning complexity.
Rare Variants:
Cervical percreta
Parametrial extension
Posterior wall percreta
Multifocal perforation sites.
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
Emergency hysterectomy specimen with [organ involvement]
Diagnosis
Placental percreta with serosal invasion
Clinical Context
Life-threatening hemorrhage, hemodynamic shock, emergency surgery
Gross Findings
Placental tissue through uterine serosa, [organ] involvement visible
Microscopic Findings
Chorionic villi and trophoblast through full myometrial thickness
Invasion Extent
Full-thickness myometrial invasion with serosal penetration
Organ Involvement
[Bladder/Bowel/Other] invasion: [present/absent], depth [X] mm
Complications
Massive hemorrhage, [blood products] units transfused
Management Outcome
Emergency hysterectomy with [organ repair], patient stable
Final Diagnosis
Placental percreta with [organ] invasion