Definite contraindication for bag and mask ventilation is:
Cleft lip
Cleft palate
Congenital diaphragmatic hernia
Umbilical hernia
c. Congenital diaphragmatic hernia(Ref: AAP guidelines 2015, Ghai 8/e p 126-133)Bag & mask ventilation should be avoided in Congenital diaphragmatic hernia, because it enlarges the stomach and small bowel and thus makes oxygenation more difficult.
New Born Infants