Hi, welcome to HCM.
There could be anything in bowel like black spots. It could be anything but it is just a finding at age 15 weeks. Meconium formation starts in 3rd trimester. Also just a less amniotic fluid
is not a appropriate finding. They must mention AFI corresponding to gestational age
I think there is no serious conditions at present. However follow up 8s very necessary.
Hope I have answered your query.