Abstract: We retrieved 11 studies. We included one trial that evaluated screening hysteroscopy versus no hysteroscopy, in women with unexplained subfertility, who were trying to conceive spontaneously. We are uncertain whether ongoing pregnancy rate improves following a screening hysteroscopy in women with at least two years of unexplained subfertility (RR 4.30, 95% CI 2.29 to 8.07; 1 RCT; participants = 200; very low-quality evidence). For a typical clinic with a 10% ongoing pregnancy rate without hysteroscopy, performing a screening hysteroscopy would be expected to result in ongoing pregnancy rates between 23% and 81%. The included study reported no adverse events in either treatment arm. We are uncertain whether clinical pregnancy rate is improved (RR 3.80, 95% CI 2.31 to 6.24; 1 RCT; participants = 200; very low-quality evidence), or miscarriage rate increases (RR 2.80, 95% CI 1.05 to 7.48; 1 RCT; participants = 200; very low-quality evidence), following screening hysteroscopy in women with at least two years of unexplained subfertility. We included ten trials that included 1836 women who had a screening hysteroscopy and 1914 women who had no hysteroscopy prior to IVF. Main limitations in the quality of evidence were inadequate reporting of study methods and higher statistical heterogeneity. Eight of the ten trials had unclear risk of bias for allocation concealment. Performing a screening hysteroscopy before IVF may increase live birth rate (RR 1.26, 95% CI 1.11 to 1.43; 6 RCTs; participants = 2745; I² = 69 %; low-quality evidence). For a typical clinic with a 22% live birth rate, performing a screening hysteroscopy would be expected to result in live birth rates between 25% and 32%. However, sensitivity analysis done by pooling results from trials at low risk of bias showed no increase in live birth rate following a screening hysteroscopy (RR 0.99, 95% CI 0.82 to 1.18; 2 RCTs; participants = 1452; I² = 0%). Only four trials reported complications following hysteroscopy; of these, three trials recorded no events in either group. We are uncertain whether a screening hysteroscopy is associated with higher adverse events (Peto odds ratio 7.47, 95% CI 0.15 to 376.42; 4 RCTs; participants = 1872; I² = not applicable; very low-quality evidence). Performing a screening hysteroscopy before IVF may increase clinical pregnancy rate (RR 1.32, 95% CI 1.20 to 1.45; 10 RCTs; participants = 3750; I² = 49%; low-quality evidence). For a typical clinic with a 28% clinical pregnancy rate, performing a screening hysteroscopy would be expected to result in clinical pregnancy rates between 33% and 40%. There may be little or no difference in miscarriage rate following screening hysteroscopy (RR 1.01, 95% CI 0.67 to 1.50; 3 RCTs; participants = 1669; I² = 0%; low-quality evidence). We found no trials that compared a screening hysteroscopy versus no hysteroscopy before IUI. At present, there is no high-quality evidence to support the routine use of hysteroscopy as a screening tool in the general population of subfertile women with a normal ultrasound or hysterosalpingogram in the basic fertility work-up for improving reproductive success rates. In women undergoing IVF, low-quality evidence, including all of the studies reporting these outcomes, suggests that performing a screening hysteroscopy before IVF may increase live birth and clinical pregnancy rates. However, pooled results from the only two trials with a low risk of bias did not show a benefit of screening hysteroscopy before IVF. Since the studies showing an effect are those with unclear allocation concealment, we are uncertain whether a routine screening hysteroscopy increases live birth and clinical pregnancy, be it for all women, or those with two or more failed IVF attempts. There is insufficient data to draw conclusions about the safety of screening hysteroscopy.

Plain-language summary: For women wishing to become pregnant spontaneously, we found one trial (200 women). For women undergoing IVF, we included ten trials (3750 women). All trials evaluated the effects of screening hysteroscopy compared to no hysteroscopy. The evidence is current to September 2018. In women wishing to become pregnant spontaneously, hysteroscopy was associated with a higher chance for an ongoing and clinical pregnancy in one study at high risk of bias. The trial reported no adverse events following hysteroscopy. The miscarriage rate was higher following hysteroscopy. In women undergoing IVF, the included studies suggested that performing a screening hysteroscopy first, improved the chances of live birth or clinical pregnancy. However, adverse events following hysteroscopy were poorly reported, and therefore, we were unable to assess the safety of this intervention. For women at a typical clinic with a 22% live birth rate, performing a screening hysteroscopy would be expected to result in live birth rates between 25% and 32%. There was no increased risk of miscarriage following hysteroscopy. We found no trials with women who were seeking intrauterine insemination. There was very low-quality evidence from one study in women who were trying to become pregnant spontaneously. There was low-quality evidence that a screening hysteroscopy, performed prior to IVF, may increase the chance of live birth or clinical pregnancy, and very low-quality evidence about adverse events following hysteroscopy. The quality of the evidence was reduced because of risk of bias and statistical heterogeneity.