Definition/General
Introduction:
Umbilical cord thrombosis is a serious vascular complication involving clot formation within umbilical vessels
It occurs in 1 in 1,300 to 1 in 3,000 deliveries
The condition may involve arteries, veins, or both
It is associated with significant perinatal morbidity and mortality.
Origin:
Results from vascular injury or stasis within umbilical vessels
May be caused by cord compression, torsion, or knotting
Endothelial damage initiates coagulation cascade
Hypercoagulable states increase risk
Associated with inflammation and infection.
Classification:
Classified by vessel involvement: arterial, venous, or mixed
Acute versus chronic thrombosis
Partial versus complete vessel occlusion
Single vessel versus multiple vessel involvement.
Epidemiology:
Incidence: 1 in 1,300-3,000 deliveries
Higher risk with maternal thrombophilia
More common with cord abnormalities
Associated with 10-40% fetal mortality
Arterial thrombosis more common than venous.
Clinical Features
Presentation:
Fetal distress during labor
Abnormal fetal heart rate patterns
Intrauterine fetal death (10-40%)
Meconium-stained liquor
Growth restriction
Emergency cesarean section indication.
Symptoms:
Variable decelerations on monitoring
Bradycardia or tachycardia
Decreased fetal movements
Signs of fetal hypoxia
Stillbirth in severe cases
Neonatal complications.
Risk Factors:
Maternal thrombophilia
Antiphospholipid syndrome
Diabetes mellitus
Cord abnormalities (knots, torsion)
Infection (chorioamnionitis)
Maternal age >35 years.
Screening:
Color Doppler ultrasound
Umbilical artery flow assessment
Fetal monitoring during labor
Maternal thrombophilia screening
Cord examination at delivery.
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Gross Description
Appearance:
Firm, dark areas within umbilical cord
Vessel distension at thrombosis site
Hemorrhage may be present
Color changes from red to brown
Cord may appear swollen or edematous.
Characteristics:
Palpable hardness in affected vessel
Segmental involvement common
May show vessel wall necrosis
Surrounding edema in Wharton's jelly
Surface discoloration possible.
Size Location:
Location: any cord segment
Fetal end more commonly affected
May involve short or long segments
Multiple sites possible
Cord length usually normal.
Multifocality:
May involve single or multiple vessels
Arterial thrombosis more common
Venous involvement less frequent
Segmental pattern typical.
Microscopic Description
Histological Features:
Intravascular thrombus composed of fibrin and platelets
Vessel wall damage with endothelial loss
Inflammatory infiltrate around vessels
Organization of thrombus over time
Surrounding Wharton's jelly edema.
Cellular Characteristics:
Platelet aggregates and fibrin mesh
Red blood cells trapped in clot
Inflammatory cells (neutrophils, macrophages)
Endothelial denudation
Smooth muscle cell damage.
Architectural Patterns:
Complete or partial vessel occlusion
Layered thrombus structure
Recanalization attempts possible
Vessel wall thickening
Perivascular inflammation.
Grading Criteria:
Assessment of occlusion degree
Thrombus age determination
Inflammatory response severity
Vessel wall damage extent
Organization and recanalization.
Immunohistochemistry
Positive Markers:
CD31 highlights damaged endothelium
CD34 in vessel walls
Fibrin stains highlight thrombus
CD68 marks macrophages
Smooth muscle actin in vessel walls.
Negative Markers:
Cytokeratin negative in thrombus
S-100 negative
No specific negative markers required
Normal tissue markers absent in thrombus.
Diagnostic Utility:
Confirms vascular nature of lesion
Identifies thrombus composition
Assesses vessel wall integrity
Distinguishes from other lesions
Evaluates inflammatory response.
Molecular Subtypes:
No specific molecular classification
Coagulation markers may be elevated
Inflammatory markers present
Endothelial dysfunction markers.
Molecular/Genetic
Genetic Mutations:
Thrombophilia gene mutations possible
Factor V Leiden
Prothrombin G20210A
MTHFR mutations
Protein C, S deficiency
Antithrombin deficiency.
Molecular Markers:
Coagulation cascade activation
Inflammatory mediators upregulated
Endothelial dysfunction markers
Hypoxia-inducible factors
Apoptosis markers.
Prognostic Significance:
Complete occlusion poor prognosis
Multiple vessel involvement worse outcome
Early gestational age increases risk
Associated with neurological sequelae
High recurrence risk.
Therapeutic Targets:
Anticoagulation controversial in pregnancy
Delivery timing optimization
Neonatal resuscitation
Thrombophilia screening
Genetic counseling.
Differential Diagnosis
Similar Entities:
Cord hematoma
Vessel compression
Vasospasm
Cord edema
Inflammatory vessel changes.
Distinguishing Features:
Thrombosis: intravascular clot
Thrombosis: vessel occlusion
Hematoma: extravascular blood
Compression: vessel flattening
Vasospasm: no thrombus
Edema: tissue swelling.
Diagnostic Challenges:
Thrombus age determination
Distinguishing from postmortem clot
Sampling adequacy
Clinical correlation importance
Cause identification.
Rare Variants:
Septic thrombosis
Tumor-associated thrombosis
Drug-induced thrombosis
Thrombosis with vessel rupture
Recurrent thrombosis.
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
Umbilical cord measuring [X] cm with abnormal segment
Thrombosis Location
Location: [segment] of cord, involving [artery/vein/both]
Vessel Occlusion
Occlusion: [partial/complete], affecting [percentage] of vessel lumen
Thrombus Characteristics
Thrombus: [acute/chronic/organizing], composed of [fibrin/platelets/mixed]
Vessel Wall Changes
Vessel wall: [intact/damaged], [present/absent] endothelial loss
Inflammatory Response
Inflammation: [mild/moderate/severe] perivascular infiltrate
Clinical Significance
Clinical significance: [risk assessment] for fetal complications
Final Diagnosis
Umbilical cord thrombosis, [vessel type], [extent]