HELP!! Ducking hatched with a growth on his underside!

[Mibbens]

Today (10/23/17 5:00pm) one of our baby ducks hatched with a growth under him. He was almost two days late hatching and we had to help him hatch the rest of the way after a couple hours of struggling. When we finally got his shell off, we noticed something odd under him.
After doing some research it sounds like he has an unabsorbed yolk sac, but I'm not completely convinced.
Right now we have him resting on a wash cloth in the incubator.
We are extremely worried.
Even if this is something very simple any advice would help.

 

[Pyxis]

That's not a growth, his belly just hasn't finished closing up from absorbing the yolk. Pop him in a cup lined with paper towels in the incubator and give him a few hours and he will be right as rain

 

[Mibbens]

What a relief!
It's been almost two hours and we've seen significant progress. Can't thank you enough!!!

 

[sourland]

As Pyxis said it is just an unabsorbed yolk sack from hatching too soon. It can provide an 'entry' for bacteria into the duckling's abdomen. You may want to apply some antibiotic ointment.