I wouldnt rule out a blockage/tube closure possibly even a "blowout". The debris is most likely undeveloped sperm cells and round cells, these are present in most samples. I wouldn't rule out agglutination. Have you tried vitamins?
Our second sa was quite reduced so we started dh on vit c 1000mg, vit e 400iu, zinc 15mg and tribulus 1200mg daily. Improvement was marked.
Vit c will help with agglutination, count and motility, vit e & zinc help create healthy vitality and tribulus increases testosterone thus increasing count and supposedly reduces antisperm antibodies.
Count isnt everything, live in hope had a poor count and managed pregnancy just 16 weeks after vr, we have a "normal" count and cant get pregnant.
I would start vitamins and get a retest in approx 6 months unless you start icsi before then x