Thanks for your query.Based on the facts that you have posted it appears that you have
doubt that your husband has undergone Vasectomy
You have consulted qualified infertility
specialist and semen analysis
report of your husband revealed agglutination of sperms.
The agglutination of sperm itself indicates that there are sperms in the semen (but they are clumped together ) which confirms the patency of Vas and rules out Vasectomy being done.
However the only confirmative test is radiological test of Vasovasogram for which he may not agree or it may create embarrassing situation for both of you and create problems in your relationship.