Our study demonstrated that some infertile women could succeed in spontaneous conception after 4D-HyCoSy and their conception rates are up to 40.9%. The mean conception time was (8.8 ± 0.3) months within a year after 4D-HyCoSy, and that may recommend infertile women to have expectant treatment for a certain time to reduce overtreatment and clinical risks .The positive effect of 4D-HyCoSy is probably due to mechanical action of the fluid. The passage of liquid breaks up minor adhesion within the tubes [4, 20] .
The conception rate of infertile women within a year after 4D-HyCoSy was higher than those reported by Chunyan Gao et al (40.9% vs. 26.59%) [20]. There may be two reasons, first, this may due to that we excluded some infertile patients with semen abnormalities of their husbands, second is the relatively large proportion of bilateral tube patency (67.5% vs. 62.0%) and small proportion of bilateral tube obstruction (9.5% vs. 13.2%) in our study .In addition, the incidence of spontaneous conception in a year after 4D-HyCoSy in our study was higher than those who accept hysterosalpingo-foam sonography (HyFoSy) used ExEm-gel(40.9% vs. 19%)༻22༽. On the other hand, the incidence of conception rate in a year after tubal flushing among those who accepted HSG used oil contrast (32.1%) or water contrast(23.6%) was relatively lower than our study (40.9%)༻18༽. Since those patients needed routine contraception for 3 months after HSG, which is beyond the period of highest conception rate (up to 21.5%) in our study, we assumed that they might have missed the best conception period. Our results showed that the mean conception time was (8.8 ± 0.3) months within a year after 4D-HyCoSy, which indicated that some infertile women could succeed in spontaneous conception within a short time after 4D-HyCoSy. Furthermore, we found out that fallopian tubes patency was significantly associated with spontaneous conception, which is consistent with the previous studies༻4,20༽. These studies suggested that infertile women with type VI should be considered (5.0 ± 2.1) months for expectant treatment, whereas (9.0 ± 0.5) months is typical for type IV and type V infertile women.
In our study, there were only 9 women with type III tubes, and their conception rate reached 44.4%. In this group, women with infertility who succeed in spontaneous conception had short duration of infertility, mostly about 1 year. Therefore, for infertile women with one tube obstruction but short duration of infertility, 8 to 9 months of expectant treatment should be considered.
Theoretically, it was challenging to achieve spontaneous conception among type I infertile patients, and therefore, clinical interventions was necessary [23]. Our study included exceptional cases, i.e. Four infertile patients achieved spontaneous conception, probably due to the passage of liquid through the tube that removed the buildup of material inside it, and the other might be due to the false-positive results of tubal spasm during 4D-HyCoSy.
Regression analysis showed that duration of infertility (less than 2 years) was significantly associated with spontaneous conception after 4D-HyCoSy, which was consistent with published studies [4]. The reason might be that long-term tubal obstruction caused by chronic inflammatory reaction damaged the internal structures including the cilia, and made it difficult to achieve spontaneous conception༻24༽. Therefore, we strongly recommend that infertile women should undergo 4D-HyCoSy examination as early as possible. Alternatively, infertile women with duration of infertility less than 2 years after 4D-HyCoSy can consider about 8 to 9 months of expectant treatment.
However, our study has two significant limitations. We did not compare the spontaneous conception rate of infertile women who did not undergo 4D-HyCoSy in outpatient clinics or underwent immediate clinical management (laparoscopic surgery, ART) after 4D-HyCoSy, which need further research in future.
The clinical importance of our results is that some infertile patients could be performed expectant treatment for a certain time after 4D-HyCoSy, which could reduce overtreatment and clinical risks and save medical resources.