Unexplained infertility is infertility which remains without a known cause even after tests such as semen analysis in the man and assessment of ovulation and fallopian tubes in the woman.

Possible causes

In unexplained infertility, abnormalities are likely to be present but not detected by current methods. Possible problems could be that:

  • The egg is not released at the optimum time for fertilisation
  • The egg may not enter the fallopian tube
  • Sperm may not be able to reach the egg
  • Fertilisation may fail to occur
  • Transport of the zygote (fertilised egg) may be disturbed

Implantation fails

It is increasingly recognised that egg quality is of critical importance and women of advanced maternal age have eggs of reduced capacity for normal and successful fertilisation.

How common is it?

It has been suggested that up to 28per cent of infertile couples have unexplained infertility.

Management and treatment options for unexplained infertility

The most efficient management of unexplained infertility appears to be administration of Clomiphene citrate or injectable hormones and performance of intrauterine insemination (IUI) during three menstrual cycles and, if this has not resulted in pregnancy, it appears most useful to subsequently perform in vitro fertilisation (IVF) in six menstrual cycles.

Clomid and timed intercourse for unexplained fertility

Three to six months of treatment with Clomid (Clomiphene citrate) pills might improve fertility by as much as two times as compared to no treatment. If a woman is already having regular periods and ovulating one egg every month, giving Clomid, will probably stimulate the ovaries to release two or three eggs per month (instead of one).

Clomid or injectable gonadotrophins plus intrauterine insemination (IUI) for unexplained infertility

Treatment with Clomid tablets or injectable hormones plus IUI improves fertility rates. For unexplained infertility, studies have shown that for women under 35, monthly success rates for Clomid plus insemination are about 14per cent per cycle. This pregnancy rate holds up for about three tries and the success rate is considerably lower after that.

The insemination component boosts fertility more than the Clomid does – but success rates are higher when they are used together.

Injectable gonadotrophins plus intercourse

This is less extensively studied. It is not yet known whether the ovarian stimulation and the insemination have independent beneficial effects or whether their beneficial effects are only seen when they are used in combination. Most likely they both independently increase fertility potential, with relatively more fertility benefit coming from the IUI component.

Assisted reproductive technologies and IVF as treatment for unexplained infertility

In vitro fertilisation (IVF) has high success in young women with normal ovarian reserve testing and unexplained infertility. Most couples with unexplained infertility with a female partner under age 40 will try about three artificial inseminations and if not pregnant – try IVF.

Ref: 14-18-152
Review date: 04/20