Hysteroscopy seems to be an effective method of treating RPOC. Our study reported a complete removal rate of 80.5% (29/36) with one procedure. The normal menstruation recovery rate after 1 year of follow-up was 91.6% (33/36). A low rate of postoperative intrauterine adhesions (2.8% [1/36]) was also reported. The complications of hysteroscopic surgery can be divided into early complications, which include bleeding, uterine perforation, infection, and fluid overload, and late complications, such as incomplete resection and intrauterine adhesions [5]. A meta-analysis reported that hysteroscopy was associated with lower intrauterine adhesion rates and incomplete evacuations when compared with dilation and curettage in women with suspected RPOC [6]. Postoperative intrauterine adhesion was detected by ultrasound in one patient who had marginal placenta previa during cesarean delivery. The residual product was 5.8 × 4.9 × 5.5 cm. This patient underwent hysteroscopy twice to remove the intrauterine residual product. This patient also had decreased menstrual blood volume. Another patient who had decreased menstrual blood volume had partial placenta implantation and underwent hysteroscopy once and laparotomy once. The residual product was 6.0 × 5.9 × 5.7 cm. The last patient with decreased menstrual blood volume had a uterine arteriovenous fistula whose residual product was 2.7 × 1.8 × 2.0 cm.
The current standard treatment method for retained products of contraception includes ultrasound-guided dilation and curettage or hysteroscopy. We chose to perform hysteroscopy for RPOC. Previous studies reported high rates of complete resection and low rates of complications for hysteroscopy performed for RPOC. Vitale et al. performed a meta-analysis of 20 studies that focused on hysteroscopy for RPOC and revealed a 91% complete resection rate, 7% incompletion rate, and 2% complication rate [7]. Rein et al. compared ultrasound-guided dilation and curettage and hysteroscopy for RPOC and reported that hysteroscopy had advantages such as fewer postoperative intrauterine adhesions and increased pregnancy rates [8]. Based on our experience, we recommend hysteroscopy for RPOC because of its high complete resection rate and low complication rate. Hysteroscopy techniques include hysteroscopic morcellation, cold loop resection, and heat loop resection. Morcellation and cold loop resection are mechanical techniques with the advantage of precise positioning, reduced damage to surrounding tissues, and the ability to reach the narrow part of the uterine horn. Studies that compared morcellation and loop excision for RPOC concluded that there were no significant differences in complete resection rates and reproductive outcomes [9, 10]. However, no clinical studies have compared the surgical outcomes of the three techniques. We believe that heat loop resection can play a role in the rapid removal of large lesions that remain in the uterine cavity. Cold knife resection and morcellation have good excision effects; therefore, they are appropriate for treating RPOC located at the uterine horn and lesions implanted in the uterine muscle layer. For complex situations, the three aforementioned methods should be combined (Fig. 1). In addition to these hysterectomy techniques, in-office hysteroscopy with the see-and-treat approach has been approved as an effective method for the management of RPOC. Nappi et al.reported that the office hysteroscope had the advantages of avoiding general anesthesia, decreasing the costs and a good compliance of patients, which also successfully used in Cesarean Scar Pregnancy combined with uterine artery embolization [11].In addition, Raz et al. compared in-office hysteroscopy with operative hysteroscopy for treating RPOC ≤ 2 cm. Operative hysteroscopy was reported to be associated with significantly more surgical complications and longer procedure and assistant times [12].
Based on our clinical experience, we recommend the time for treating RPOC. To our knowledge, no other study has shared similar experiences. RPOC associated with early-term and mid-term pregnancy should be surgically removed as early as possible to reduce the risk of bleeding and prevent intrauterine adhesions. If there is no massive vaginal bleeding after late pregnancy, hysteroscopic surgery should be delayed until the volume of the uterus shrinks after puerperium. This can reduce the surgical difficulty, operative time, bleeding, and risk of hysteroscopic water poisoning and air embolism, and improve the probability of operative success. In addition, RPOC that exist after hysteroscopic surgery are a clinical problem, and their optimal treatment method is debatable. If the residual product is small and the patient has no active vaginal bleeding, then we recommend drug treatment. However, if the remaining lesions are large and include implantation and bleeding during hysteroscopy, laparotomy can be performed to remove them.
It is important to differentiate between RPOC and uterine arteriovenous fistulas to avoid overtreatment. A uterine arteriovenous fistula comprises abnormal connections between uterine arteries and veins; it can be congenital or acquired after pregnancy or uterine surgery. Furthermore, a uterine arteriovenous fistula can cause massive bleeding. Ultrasound is the most common and convenient examination for diagnosing uterine arteriovenous fistulas. However, it cannot differentiate uterine arteriovenous fistulas from RPOC [13]. MRI and arteriography can be used to diagnose RPOC and uterine arteriovenous fistulas [14]. Based on our experience, the preoperative examination to exclude the existence of uterine arteriovenous fistula is important. Hysteroscopy can help to differentiate RPOC from uterine arteriovenous fistulas. The four patients in our study with a suspected uterine arteriovenous fistula underwent MRI, arteriography, and hysteroscopy, which verified that only three of those patients had a uterine arteriovenous fistula.
Our retrospective study elucidates the use of hysteroscopy for RPOC. However, it was limited by the small number of patients. Nevertheless, we were able to share new perspectives regarding the optimal surgical methods and time for treating RPOC as well as our experience treating residual products with hysteroscopy.
