Unless your product has already been on the market, the FDA will not allow you to take your product to market if your Design Controls are not deemed safe and effective. Design controls are documented, objective evidence you establish throughout the product development process to prove your device is safe and effective. There is almost no way to submit a 510k or PMA without your design controls and design history file. They don’t necessarily have to be a part of the submission but logically they should be, and they should be established prior to submission.
Once submitted there are several things that the FDA can bring up to delay your approval process.
Some common mistakes that I found from an article include:
1. Inadequate device description
2. Discrepancies throughout submission
3. Problems with indications for use
4. Failure to follow or address current guidance or recognized standards
5. Inadequate or missing performance or clinical data
6. Comparison to predicate is missing or inadequate
7. Other testing data is missing or inadequate
Source: http://www.emergogroup.com/blog/2015/05/seven-mistakes-can-delay-your-fda-510k-clearance