Can a successful reversal go back?

My husband had a reversal in November 2011.  After waiting 6 weeks for recover I got pregnant March 2012 after just 3 months of trying.  I am very thankful and feel so blessed for us to have a perfect little girl in December 2012. We have been trying for a second for about 10 months now and nothing. Is it possible can his reversal go back. Maybe scar tissue blocked it?