Echogenic Amniotic Fluid
Paula J. Woodward, MD
DIFFERENTIAL DIAGNOSIS
Common
Normal Variant, Third Trimester
Placental Abruption
Bowel Anomalies
Jejunal, Ileal Atresia
Gastroschisis
Less Common
Exencephaly, Anencephaly
Umbilical Vessel Disruption
ESSENTIAL INFORMATION
Key Differential Diagnosis Issues
Echoes in amniotic fluid may be normal, particularly with high resolution transducers
Look for anomalies, especially of gastrointestinal tract
Ask about vaginal bleeding
50% of abruption cases have no sonographic findings acutely
Ask about previous procedures
Patient may be asymptomatic despite intraamniotic, subchorionic bleeding secondary to intrauterine procedure
Helpful Clues for Common Diagnoses
Normal Variant, 3rd Trimester
Vernix may layer over cervix
Placental Abruption
Initial subchorionic bleed → small breach in membranes → blood mixes with amniotic fluid → diffuse ↑ echogenicity
May see clot adherent to cord or fetus
Clot decreases in echogenicity as it ages → linear echo from chorion with amniotic fluid on one side, old hypoechoic clot on other side
Jejunal, Ileal Atresia
Fetal regurgitation secondary to small bowel obstruction
Multiple dilated loops of bowel within abdomen
Gastroschisis
Non membrane-bound abdominal wall defect
Cord inserted adjacent to defect
Bowel loops float freely in amniotic fluid
Meconium stained fluid typical at delivery of gastroschisis infants
Helpful Clues for Less Common Diagnoses
Exencephaly, Anencephaly
Skull vault bones absent
Proptotic orbits create “frog eye” appearance
Trauma to exposed brain results in fragmentation
Look for linear amniotic bands as etiology
Umbilical Vessel Disruption
Umbilical vessel bleeds into amniotic fluid
Risk factors include intrauterine procedures, rupture of varix in free loops
Other Essential Information
Check fetal cardiac activity and look for bleeding at the end of every invasive procedure
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