I'd like to echo what Attilathemeercat said. The depth of testing available on the NHS is utterly woeful - fertility isn't a priority area for the NHS, so sadly if you want to REALLY find out what's going on, you're probably going to have to go private. There are two NHS sites I know of who look at testing in more depth - Dr. Siobhan Quenby's clinic at Liverpool Women's Hospital, and Dr. Hassan Shehata via Epsom and St. Helier hospital. And even then the focus is largely preventing rpt mc, rather than unexplained infertility. As ATMC said, if it's 'unexplained' that just means you haven't had a proper diagnosis.
To add to the list of tests ATMC just posted, here are what you can reasonably expect at the clinics which specialise in repeated IVF failure or rpt MC. (Get comfy, it's long!)
Karyotyping for DH and you (tests for any genetic issues)
Sperm assays and investigations - including DNA fragmentation testing(anyone with more info. on this as I know v. little about this)
Uterine
Hysteroscopy, HSG etc. to check for scarring, fibroids, polyps etc
Thin lining, no triple stripe etc.
Doppler - to check blood flow in uterus
Insulin resistance (fasting glucose test)
Thyroid levels (TSH, T3, T4)
Anti Nuclear Antibodies
Anti thyroglobulin
Anti-thyroid antibodies
Full Blood count
ESR (Erythrocyte Sedimentation rate)
RA (Rheumatoid Arthritis)
BLOOD CLOTTING PANEL (Thrombophilia panel)
Serum Immunoglobulins (IgG, IgM and IgA)
Activated Protein C Resistance
Factor V Leiden genotype
Anti Phospholipid Antibodies
Lupus Anticoagulant
Anti Cardiolipin Antibodies
Plasma Free Protein S level
Factor II G20210A
Prothrombin Gene Mutation
Antithrombin III M
Fibrinogen level
APTT (Activited Partial Thromboplastin Time)
APTR
MTHFR (methylenetetrahydrofolate reductase) and connected with this is measurement of your homocysteine levels (The GP may not be able to do this one)
BACTERIAL
Mycoplasma,
Ureaplasma
Bacterial vaginosis
Chlamydia and any other bacterial infections
Varicella Zoster antibodies
Progesterone
Extra progesterone e.g. Gestone (injectible progesterone) may also be needed.
Get progesterone levels checked at the same time as any beta tests (or even 1 week after embryo transfer) to make sure you have adequate levels (especially if you have had a cycle where you have started bleeding before the end of the 2ww).
Immune testing (so called Chicago or Level 2 tests) - to be done by specialist consultant:-
Natural Killer Cells
Cytokines, (TH1, TH2)
Tnf-alpha
DQ Alpha
LAD
Pretty hefty, no?! My problem, it turned out, was Natural Killer cells going haywire, and this was sorted as I started IVF, although if I'd been a bit younger, we could have ttc 'naturally' for a bit, with my NK cells managed by steroids. I'd had enough by then though, and went straight for IVF, which worked first go. If we hadn't have got this sorted, the IVF itself would have been doomed to fail.
For those that are scared of IVF, it's no more scary than IUI in my opinion - similar levels of prodding and poking, but more drugs.
I was so fed up with everything, I was thrilled to get going with something that I could finally believe had a good chance of working, so it was a relief really! And it's only 3 weeks out of your life, max, compared with years of sadness.
Hope this helps someone. x