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Twin Demise Surveillance & Hemodynamic Visualizer

Single Fetal Demise (sFDIU) Clinical Pathophysiology & Evidence-Based Surveillance Navigator
Placental Vascular Anastomoses & Hemodynamic Cascade Monochorionic-Diamniotic (MCDA)
Stable Baseline
SHARED CHORIONIC PLACENTAL BED (VASCULAR COTYLEDONS) Twin A Viable Donor 55 mmHg Twin B Surviving Co-Twin 55 mmHg Superficial AA Anastomosis (Bidirectional) Deep Cotyledon AV Shunt Superficial VV Connection
Co-Twin MAP (Mean BP)
55 mmHg
Euvolemic & Stable
Cerebral Perfusion
100%
Optimal Oxygenation
Anastomotic Shunt ΔP
0 mmHg
Balanced Exchange
Acute Anemia Status
None
Hb ~14.2 g/dL
Hemodynamic Shockwave Pathophysiology
Evidence Mechanism
In Monochorionic (MC) gestations, nearly 95% of placentas harbor vascular anastomoses (Arterio-Arterial, Arterio-Venous, and Veno-Venous). When single intrauterine fetal demise (sFDIU) occurs:

1. Immediate Pressure Sump & Retrograde Exsanguination

The heart of the demised twin ceases pumping, converting its circulation into an open, low-resistance, flaccid vascular sump. Within seconds to minutes, massive volume shifts from the surviving co-twin into the dead twin across large arterio-arterial (AA) or veno-venous (VV) connections.

2. Transient Profound Hypotension & End-Organ Ischemia

Acute hypovolemia triggers acute systemic hypotension in the survivor. This watershed hypoperfusion preferentially inflicts ischemic injury on fragile neonatal brain territories—predisposing to periventricular leukomalacia (PVL), multicystic encephalomalacia, and porencephaly.

3. Dismantling the "Embolic Theory"

Historically, injury was attributed to thromboplastic material embolizing from the deceased twin. Contemporary hemodynamic Doppler and fetal autopsy evidence proves the primary culprit is acute exsanguination and hemodynamic shockwave at the moment of demise.

Dichorionic (DCDA) Contrast

In DCDA gestations, separate placental masses eliminate vascular sharing. Demise of Twin A does not produce acute hypovolemic shock in Twin B. Management focuses primarily on monitoring maternal coagulation profiles and avoiding unnecessary iatrogenic preterm delivery.