Quest Diagnostics has announced it has entered into a definitive agreement to acquire Solstas Lab Partners Group and its subsidiaries for approximately $570 million.

Solstas, a commercial laboratory company based in Greensboro, N.C., is a portfolio company of Welsh, Carson, Anderson and Stowe. WCAS is a New York-based PE firm specializing in information/business services and healthcare businesses.

Quest, a provider of diagnostic information services headquartered in Madison, N.J., expects to complete the acquisition of Solstas in the first half of 2014.