Hi. Zero sperm is a condition known as azoospermia. First, make sure your DH really had ZERO sperm and not NEAR-ZERO sperm (oligospermia) or DEAD sperm (necrospermia). It makes a difference whether you have zero or one, as odd as that sounds.
Assuming your DH really has ZERO sperm, there are two types of azoospermia:
obstructive and
non obstructive. Obstructive means there is something physically blocking sperm from getting out of your DH's body; it generally indicates an issue with
sperm delivery. Common causes include scar tissue, damaged or absent vas deferens (tubes that carry sperm from the testicles and out the body), or varicoceles (a varicose vein in the scrotum). Some of these are treatable, others are not. For those that not, there are ways to work around them (for example, getting sperm directly from your DH's testicles or epididymus, as Heather mentioned). So, there is hope. Non-obstructive azoospermia is a bit more complicated. This generally indicates an issue with
sperm production. Your DH's body is just not making sperm, which is harder to fix. Common causes include testicular failure, hormonal imbalance and chromosomal diseases (such as Klinefelters). Additionally, not to get all technical here, but the issue may not even be sperm production, but
sperm maturation. The difference being that with the latter, your DH's body is producing sperm, but for some reason they are dying before they can mature fully and go where they need to go. In order for sperm to mature, there must be certain types of cells to carry sperm through the 5 stages of development. If you are missing any of these cells, sperm development can completely halt. Some of these issues related to sperm production and sperm maturation can be fixed, others cannot. But even for those that cannot, there are again ways to work around it, so don't worry just yet.
Your best bet is to see a urologist asap. They will need to do a bunch of testing to find out what the cause of your DH's issue is. They will do a physical exam, ultrasounds and bloodwork to determine if your DH has obstructive or non-obstructive azoospermia. That is the first step and your treatment will depend entirely on the kind of azoospermia you have. (Your urologist may also test DH for a condition called retrograde ejaculation where sperm actually gets pulled back into the body - the opposite way it's supposed to go- each time DH ejaculates. There is a test called postejaculate urinalysis that can rule this out pretty quickly.) Options that may be available to you include hormonal therapy, Clomid, vitamins, and various sperm extraction techniques such as TESE, PESA, MESA etc (worthy of their own post and easy enough to google if you're interested).
Bottom line is, don't lose hope. Prepare for a long, emotional, exhausting journey, but know that there are ways to get pregnant with today's incredible medical technology as long as you have the resources and the faith to keep going on.
Good luck - Juli
PS - ladies, I know way too much about this stuff