Most cases with acquired uterine diverticulum have caesarean scar syndrome, which developed after undergoing a caesarean section [1]. Acquired uterine diverticulum after myomectomy has been reported in few cases, all discovered during pregnancy [5]. This is the first report, to our knowledge, to describe diverticulum development after myomectomy in a non-pregnant patient. The prevalence of caesarean scar syndrome after caesarean section ranges from 56% to 80% [6]. A diverticulum reportedly develops in approximately 18% of cases after enucleation of a uterine myoma [5], and the diverticulum frequency after caesarean section is considered to be high. The following are considered to be the causes of uterine diverticulum after caesarean section: 1. incision at a relatively low position near the cervix region; 2. single-layer suture, locking suture, incomplete closure; and 3. factors that induce the formation of adhesions, such as non-closure of the peritoneum and improper hemostasis [2][6][7].
In patients who have undergone caesarean section, one of the causative factors might be that the incision site is in the lower uterine segment. The lower uterine segment is potentially weak at the Müllerian duct junction [8]. New blood vessels appear in the surgical scar, and pathologically, bleeding from these new blood vessels and inadequate drainage due to a smaller than normal muscular layer appear to lead to accumulation of fluid in the scar region. In addition, there might be an endometrial gland in the muscular layer around the scar region which results in a pathological condition like adenomyosis.
In our present patient, the pedunculated subserosal myoma was located near the cervix, such that the incision near the cervix had to be sutured. The menstrual blood trapped in the scar is also considered to result in hemorrhage. However, Tanimura et al. reported that such hemorrhage could be caused by the scar itself since they detected an endometrial gland and stromal tissue deep in the scar [2][9]. We also detected endometrial tissue in the incision site, which suggested that the patient’s abnormal bleeding could have been due to bleeding from the capsule tissue itself. It is also possible that the endometrium was pulled towards the serosa and sewn in when the pedunculated fibroid was pulled.
Laparoscopic repair of uterine diverticulum was first reported in 2008 [2], and has since been combined with hysteroscopy. With the latter approach, the scar tissue is excised under a hysteroscope and the wound is trimmed and sutured employing a laparoscope [3][4]. More recently, there have been reports on the levonorgestrel intrauterine system [6] and low dose estrogen plus progestin [10] as hormone therapy. Hormone therapy was not adopted in our present case due to the patient’s desire to have children.
In caesarean scar syndrome, especially in cases with a retroverted uterus, tension is exerted on the wound, and this has been speculated to lead to uterine diverticulum development. The failure rate of repair procedures is high in retroverted uterus cases [6], at approximately 86% [2]. Therefore, in a case with a retroverted uterus, in which lesion excision/suture is not possible, the round ligament can be sewn to reduce the tension exerted on the wound. In our present patient, the wound was on the posterior wall, which was opposite the wound observed in caesarean scar syndrome cases. Since the uterus was markedly anteflexed, leaving it as it was would have exerted strong tension on the wound in the posterior wall, which might have delayed the wound healing as well as causing recurrence. Therefore, the round ligament that was detached when searching for the ureter was not sutured. The uterine anteflexion angle was found to be loose upon comparing the uterine sagittal planes in transvaginal ultrasound images obtained the 7th day, 30th day, 3rd, and 6th month after the procedure. The release of tension on the wound is suggested to be an important procedure, in addition to sufficient trimming of the demarcated portion and careful suturing.
In parallel with the current increase in the rate of caesarean section worldwide, it is expected that late marriage and childbearing will increase the need for uterine preservation and uterine myomectomy. In the presence of the aforementioned conditions, the course may be similar to that of caesarean scar syndrome after myomectomy. The treatment methods will be similar to that applied to caesarean scar syndrome. Reducing the tension exerted on the wound is potentially useful, in addition to removing the demarcated tissue and re-suturing by employing a combination of laparoscopy and hysteroscopy. It was also suggested that uterine flexion repair with a round ligament and wound reduction by preventing. In addition, releasing cervical canal stenosis using a hysteroscope and a Neraton catheter may be beneficial.