2,516. Displacement After Shechita
Hilchos Shechita 3:16
If the sign that was cut for shechita is found to displaced, the shechita is valid because it was clearly displaced after slaughtering. Had it been displaced before slaughtering, it would have drooped and it would have affected the ability to slaughter the animal or bird.
Hilchos Shechita 3:17
The preceding halacha only applies when a shochet didn’t hold the signs in his hand while cutting them. If he held the signs while performing the slaughter, it is possible that the signs could have been cut after being displaced. Accordingly, if a sign is both displaced and slaughtered, there’s a doubt as to whether the animal or bird is a neveila.