To our knowledge, this is the first report on the mortality rate after myomectomy from a large database of over 6 million patients. Based on data obtained from the HIRA-NIS, we found that the mortality rate after myomectomy was 1.3 ± 0.8 per 10,000 patients (0.013%) among women aged 15–55 years from 2009 to 2018. The mortality rate after myomectomy was considerably lower than that reported in the past. One patient who underwent myomectomy died, and this patient did not have concomitant VTE. The incidence rates of VTE, DVT, and pulmonary embolism (PE) after myomectomy were 0.057%, 0.044%, and 0.025%, respectively. The conversion rate to hysterectomy after myomectomy was 2.9 ± 1.1 per 10,000 patients (0.029%). These values were also considerably low.
Uterine leiomyomas (myomas or fibroids) are the most common type of pelvic tumors in women, with a lifetime risk of approximately 70–80%20. There are many treatment options for leiomyoma-related symptoms, including expectant treatment, medical treatment, non-excisional procedures (magnetic resonance guided focused ultrasound, endometrial ablation, uterine artery embolization), and surgery (radiofrequency ablation, myomectomy, hysterectomy)3. Myomectomy is performed to remove leiomyomas surgically from the uterus, keeping the uterus in place for women who wish to become pregnant or retain the uterus.
At the turn of the 20th century, compared with the mortality rate of 6–7% for abdominal hysterectomy, abdominal myomectomy was associated with a mortality rate of 40%4,6. Hemorrhage and embolism have been the main causes of death in myomectomy patients6. There are three possible complications associated with the operation, namely hemorrhage, postoperative morbidity, and mortality. The incidence of these complications was observed to gradually reduce with improvements in surgical techniques. Severe hemorrhage may be addressed using a number of techniques, including intraoperative blood salvage, uterine artery ligation, tourniquet or vasoconstrictive agents, or conversion to hysterectomy. The mortality rate after myomectomy dropped to less than 1% in the 1950s6 and was no longer higher than that after hysterectomy6. In addition, there was no difference in complication rates between those who underwent myomectomy and hysterectomy21 .
Although myomectomy is a common operation in the field of gynecology, there are very few studies on the mortality associated with myomectomy. Therefore, we performed this study to investigate the current mortality rate of myomectomy in the era of advanced surgical skills and improved anesthesiology. In the Republic of Korea, where national health insurance is provided, most myomectomy data are acquired through the HIRA database. Therefore, we studied the mortality rate of myomectomy using the health insurance claims data. We also determined the VTE rate and conversion rate to hysterectomy. In the future, it is necessary to compare the current mortality rates of hysterectomy and myomectomy.
VTE has long been recognized as a possible complication and a leading cause of death in patients undergoing pelvic surgery22. Pelvic operations are more prone to complications due to VTE than operations at other sites22. PE is one of the most serious and common preventable cause of in-hospital deaths after surgery23. Without thromboprophylaxis, the risk of DVT in patients undergoing major general or gynecologic surgery is 15–30%, and the risk of fatal pulmonary embolism is 0.2–0.9%24. In a population of patients who selectively received prophylactic anticoagulants (38% of patients), the rate of VTE was 0.2%25. Patients undergoing myomectomy (major surgery, defined as lasting for > 30 minutes) are at a low-to-moderate risk of VTE and require appropriate thromboprophylaxis, whether mechanical or pharmacologic. In the Republic of Korea, the overall rates of postoperative VTE in major orthopedic, cancer, and benign surgeries were 1.24%, 0.67%, and 0.05%, respectively. Colorectal cancer surgeries (1.67%) and hip fracture (1.60%) were associated with the highest rates of VTE26. Patients undergoing surgery for ovarian, colorectal, pancreatic, and esophageal cancers and major orthopedic surgery had a > 20-fold increased risk of developing VTE than those undergoing benign surgery 26. Some authors have demonstrated that the rates of postoperative VTE in Asia, especially in the Republic of Korea, are lower than those in Caucasian populations26. For this reason, thromboprophylaxis is not commonly offered in South Korea unless a major surgery (cancer-related surgery) is performed.
In our study, the incidence rates of VTE, DVT, and PE after myomectomy were 0.057%, 0.044%, and 0.025%, respectively, in the Korean population. The incidence of VTE was considerably lower than that in the general population worldwide and even in a population of patients who received prophylactic anticoagulants (VTE incidence rate: 0.2%). PE-related mortality was reported to fall from 3.3% (2001 to 2005) to 1.8% (2010 to 2013) in one study and from 17–10% in another study27,28, with a decreasing trend each year. One of the 23,549 patients who underwent myomectomy between 2009 and 2018 died, and this patient did not have concomitant VTE. In Asian countries, such as South Korea, where VTE incidence is low, the contribution of VTE to the mortality rate associated with myomectomy is likely to be small. We believe that the considerably low mortality rates of myomectomy are due to the relatively low VTE rates in addition to improvements in surgical techniques and advanced anesthesiology methods in South Korea. However, the current study had a limitation when compared with other studies as there were no data about the body mass index and smoking status, which are often related to DVT.
Hysterectomy may be required intraoperatively to control bleeding. In our study, the conversion rate to hysterectomy during myomectomy was 2.9 ± 1.1 per 10,000 patients (0.029%). This is extremely low compared to that reported in previous studies. In cases of conversion to hysterectomy, the myomectomy code may have been omitted because there was no difference in reimbursement even if it was not entered. This could explain why the conversion rate to hysterectomy was very low in our study. Thus, future studies on the conversion rate to hysterectomy with different research methods for extracting data are required.
Myomectomy has been reported to temporarily reduce uterine volume and relieves symptoms in approximately 80% of the patients29. The risk of recurrence after myomectomy is approximately 27% for single leiomyomas and > 50% for multiple leiomyomas30. If the first surgery is performed for a single leiomyoma, 11% of the women require subsequent surgery31 ; if multiple leiomyomas are removed during the initial surgery, 26% require subsequent surgery.
Our study has several limitations. First, the mortality rates in this study may be lower than the actual rate because the incidence rates in this study included only those recorded in medical institutions. Therefore, deaths outside these institutions may not have been incorporated in this study. Additionally, sudden death occurring as a side effect of myomectomy is rare. Considering the narrow land area, the density of medical institutions, relatively low medical expenses, and free emergency transportation (119) provided by the county, the ratio is likely to be very low. Second, the conversion rate to hysterectomy during myomectomy may be much lower than the actual rate because the myomectomy surgical code was not included in cases of conversion to hysterectomy. Third, our study design did not distinguish between open and laparoscopic surgeries. However, there was only one recorded death, and the comparison of the mortality rates between laparoscopic surgery and laparotomy did not seem to be warranted. Fourth, the cause of death was unknown but was not related to cancer or trauma due to an accident.