"Many employers are fearful of litigation and will verify employment dates only, " Berchem said.

CNN: Controversy surrounds health care contract workers

Berchem said hospitals that do not use temporary workers tend to have more negative patient outcomes because they have fewer staffing resources overall.

CNN: Controversy surrounds health care contract workers

One of the biggest problems, Schnierer and Berchem agree, is that former hiring managers are often unwilling to disclose the reason for a past employee's termination, creating holes in a background check.

CNN: Controversy surrounds health care contract workers