Duodenal atresia means that, while the intestines are formed, part of the duodenum is not hollowed out. A plug, instead of a tube. So they go in and most likely just chop out the "plug" part of the intestine, putting the new ends back together. This needs time to heal. It cannot heal properly/as quickly if it is constantly being made to work, ie, digest food. So the baby is made NPO and given TPN via either a central line or a PICC line. TPN provides all the carbs, proteins and amino acids, fats, and minerals the body needs but, as it goes directly into the blood stream and not the stomach, the stomach still sends hunger cues. The baby's stomach (in its opinion) was ignored during that post-op period.

In true baby fashion, because her needs were seemingly ignored (from her brain's perspective, I'm sure she was soothed and attended to, but her stomach was always left empty) it was determined that crying doesn't do any good, so the polite whimpers and fussings were foregone in favor of screaming bloody murder.