This 18-week fetus has normal amount of amniotic fluid (not shown in this 1 MB video-clip). I missed on the original reading that the stomach was too small. (I use the size of the gallbladder as comparison). The fetus was born with a tracheoesophageal fistula. Fortunately this was an isolated tracheoesophageal fistula (no trisomy). Usually in the second trimester the stomach is visible even with tracheoesophageal fistula. The stomach becomes "too small" only in the 3rd trimester. See Polyhydramnios and small fetal stomach: clinical outcome and pathologic findings for more differential diagnosis and A Chance at Life for a moving account of a child born with a tracheoesophageal fistula.
Lesson: do not accept a "small stomach" as normal. Since this case we rescan all fetuses that have small stomach.