You can use operator 'having' in query to detect empty values and show this counter for filtering:
Select Top 1000000 tblADObjects1.domain,
tblADObjects1.sAMAccountName,
tblADGroups.Name,
tblADGroups.Description,
tblADGroups.LastChanged
From tblADGroups
Left Join tblADMembership On tblADGroups.adobjectid =
tblADMembership.parentadobjectid
Left Join tblADObjects On
tblADObjects.ADObjectID = tblADMembership.ChildAdObjectID
Inner Join tblADObjects tblADObjects1 On tblADObjects1.ADObjectID =
tblADGroups.ADObjectID
Group By tblADGroups.Name,
tblADGroups.Description,
tblADGroups.LastChanged,
tblADObjects1.domain,
tblADObjects1.sAMAccountName
Having Count(tblADObjects.ADObjectID) = 0