Definition: Infertility for which no cause can be identified.
Epidemiology: Up to 30% of infertility cases do not have an explanation.
Causes: Factors that cannot be detected by standard infertility tests include
failure of implantation, genetic abnormalities in the embryo, immune issues,
subtle sperm function abnormalities, and reduction in ovarian function. Tests
for these causes are either non-standard, unproven, or non-existent. Even with
more sophisticated tests, infertility may not have an apparent cause.
Diagnosis: The diagnosis of unexplained infertility (UI) can only be made after
the basic infertility evaluation fails to reveal an obvious abnormality. Therefore,
only if the fallopian tubes are open, the semen analysis is normal, the cervical
mucus does not impede sperm function, ovulation occurs normally, and peritoneal
factors (endometriosis, scar tissue) are absent, the diagnosis can be made. The
basic tests for infertility include a semen analysis, hysterosalpingogram (test
for the fallopian tubes), confirmation of ovulation, post-coital test (controversial),
and a laparoscopy.
Treatment: By default, the treatment of unexplained infertility is by trial and
error (empiric).
- Any treatment for UI, except in vitro fertilization (IVF) will not increase
the likelihood of pregnancy more than the regular monthly conception rate of
a fertile couple.
- Expectant management: while the monthly pregnancy rate of a patient with UI
is lower than the general population, it is appropriate to offer no specific
therapy to a young patient who does not wish or cannot afford infertility treatment.
- Intrauterine insemination (IUI): with or without oral fertility medications
(clomiphene or letrozole) or fertility injections, IUI appears to improve fertility
in UI patients compared with intercourse.
- Oral fertility medications (clomiphene, letrozole): A modest increase in pregnancy
rates occurs with empiric treatment of patients with UI. Such treatment should
not be offered for more than 3-6 months since it is unlikely to result in a pregnancy
with additional treatment cycles.
- Injectable fertility medications (gonadotropins): a modest increase in pregnancy
rates occurs with this treatment but it is very expensive and entails increased
risks of multiple births and ovarian hyperstimulation syndrome.
- In vitro fertilization (IVF): Perhaps the most successful treatment for UI
but clearly the most expensive of all other treatment options. Opinions vary
as to the success rate per treatment cycle, and the results vary between IVF
programs and depend also on age and other factors. This option should be offered
when less aggressive and expensive options fail.
©Copyright Eli Reshef MD
back to Fertility Articles Main Page
