This study revealed the following two points. First, the pregnancy rate per ET was lower in patients with a history of AT than in those without a history. Second, the endometrium was thinner before ET in patients with a history of AT than in those without a history.
ART in patients with a history of AT requires more embryos to be transferred to obtain live births. To the best of our knowledge, the pregnancy rate per ET in patients with a history of AT has not been previously reported, and this is the first report of its kind. Factors that affect the pregnancy rate include the age of the embryos [13] at the time of oocyte retrieval, grade of the embryos [18], and number of embryos transferred [19]. Even in patients with a history of AT, these factors affect the pregnancy rate per ET. In this study, age, the embryo grade, the number of embryos transferred, and a history of AT were analyzed as adjustment factors, and the fact that the patients had undergone AT also affected the pregnancy rate per ET.
Although a thin endometrium is seen in patients with a history of AT [20], including those with Asherman syndrome, to the best of our knowledge, there has been no previous report of a thin endometrium in ET of ≥50 cycles. It has been speculated that postoperative changes in uterine circulation are responsible for endometrial thinning in patients with a history of AT [20], and it has also been reported that at least one uterine artery is occluded in 85% of patients with a history of AT [21]. The endometrium at the time of ET is one of the factors involved in pregnancy [22], suggesting that a thin endometrium after AT may reduce the pregnancy rate per ET.
The cumulative pregnancy and live birth rates were not different between patients with and without a history of AT. A systematic review reported cumulative pregnancy and live birth rates of 55% and 42% in patients with a history of AT, respectively [7]. Owing to the small number of patients in this study, it is not possible to conclude that the cumulative pregnancy rate of patients with a history of AT is the same as that of patients without a history of AT in terms of power. However, with continued infertility treatment, it may be possible to expect cumulative pregnancy and live birth rates similar to those of patients without a history of AT.
The present study’s results indicate that more embryos need to be transferred to achieve pregnancy after AT because of the lower pregnancy rate per ET. It is important to sufficiently explain to patients that the number of oocyte retrievals and ETs required for a live birth is higher in patients with a history of AT than in those without a history of AT and that the treatment period may be longer.
The strength of this study is that it is the first report of specific outcomes of ART in patients with a history of AT in a control setting. The present study demonstrates that AT reduces fertility. Nevertheless, this study has some limitations. First, a small number of patients was included in this retrospective study. However, the number of patients with a history of AT is limited, and it is difficult to estimate a large number of patients for a prospective study; therefore, even a small study such as this one is important [23]. Second, this study was limited to ATs. Since different surgeries, such as vaginal trachelectomy, AT, and laparoscopic trachelectomy, have been reported to have different pregnancy rates [7], it is not possible to discuss the impact of ART after other surgeries on outcomes. Third, the surgery was performed at another hospital, and the details of the surgery, such as whether uterine artery preservation was performed intraoperatively and the residual cervical canal length, which could affect postoperative fertility, are unknown. In future, multicenter studies are required to examine the outcomes of ART after AT.
In conclusion, we found that the pregnancy rate per ET was lower in patients with a history of AT than in those without a history of AT. In ART for patients with a history of AT, the pregnancy rate per ET is lower, requiring more embryos to be transferred until live birth is obtained. It has been suggested that the cause of this may involve a thin endometrium postoperatively. This means a longer period of infertility treatment to have a live child. We will continue to record the experience of each patient and accumulate knowledge of ART treatment after trachelectomy. It is important for clinicians to be aware of the longer time to pregnancy in patients on ART after AT.