This case shows a free-floating thread with an intact chorionic membrane, representing an amniotic band. It can lead to amniotic band syndrome. So, careful examination of fetal limbs is necessary. Differential diagnosis is amniotic sheet which is a shelf-like indentation of the amniotic sac made by uterine synechia, not associated with fetal anomalies. Amniotic band can resolve spontaneously during pregnancy with no fetal harm ¹.

Unfortunately, the right hand was in contact with the amniotic band, which resulted in congenital amputation of the middle three fingers of the right hand, which revealed with postnatal pediatric examination. Although the amniotic band resolved, it resulted in defective formation of fingers.

Amniotic band syndrome affects the hand in 90% of cases. The distal portion of extremities is always involved, especially the longer central fingers of the hand sparing the thumb and little finger (as in this case). In feet, it always affects the big toe.

Amniotic band syndrome is very difficult to diagnose by ultrasonography, as the band can be thin or hard to see from fetal parts. Its deforming effects can be visualized by the aid of 3D ultrasound or fetal MRI.

Echogenic/turbid amniotic fluid is reported to occur in ~4% of first and second-trimester ultrasound examinations ⁴. In this case, it could be intraamniotic bleeding secondary to the traumatising effect to fingers which could bleed. 

Middle cerebral artery Doppler can occasionally show diastolic flow reversal, a non-pathological finding that is usually due to increased intracranial pressure mostly by probe compression ^2,3. 

Additional contributor Dr. Marwan Hassan Sobhy, Gynecology specialist, Alexandria, Egypt.