Interpretation
At present, it is universally acknowledged that the laparoscopic myomectomy (LM) is a safe treatment for patients and less invasive than the abdominal approach.(20) LM has many benefits, such as reducing pain, reducing intraoperative blood loss, and accelerating recovery. (21)These studies on blood loss often refer to the visible blood loss such as intra-operative blood loss and postoperative drainage, while ignoring the existence of hidden blood loss and its impact. Understanding and evaluating HBL can help to evaluate the hemodynamic stability of patients more accurately and objectively during perioperative period.
HBL has been paid more and more attention in the study of orthopaedic surgery, and its application in gynecological surgery is still relatively rare. HBL is also becoming one of the indicators to evaluate one operation or compare two surgical methods for the same disease. Lei et al. compared open posterior lumbar interbody fusion (PLIF) and transforaminal lumbar interbody fusion (TLIF) by Wiltse approach for lumbar degenerative disease and spinal instability from the perspective of HBL.(22) In the field of gynecology, Zhao et al. studied the application of HBL in laparoscopic and laparotomy in the treatment of cervical cancer.(23) Their research reveals that HBL is seriously undervalued. However, no one has studied the comparison between LESS-M and CLM from the perspective of HBL.
Kim et al. have compared LESS-M and CLM in terms of surgical outcomes. Their research suggests that the surgical outcomes (operative time, estimated blood loss, postoperative hemoglobin drop, postoperative hospital stay, and postoperative pain scores) were not different statistically between these 2 groups. There was no result of HBL in their research. (24) Our study analyzed the difference of HBL between the two procedures and their respective risk factors.
In this study, the mean VBL was 115.4±180.6 mL in the LESS-M group. Surprisingly, our statistical analysis showed that the HBL was 364.3±252.6 mL, which was much greater than VBL. HBL is comprised up to 74.4% of TBL in the laparotomy group. These results were similar to those observed in the CLM group. The mean VBL was 187.9±198.5 mL for the CLM group, the HBL was 306.8±304.7 mL (HBL is comprised up to 58.9% of TBL). It is not difficult to make out from these data that HBL is indeed seriously underestimated. The source of HBL has not been conclusively determined. The mainstream view is that HBL may be associated with blood hemolysis, extravasation of the blood into the tissues during the operation, and blood losses during postoperative hospitalization.(25-27) Comparing these two groups, we found that LESS-M group had more HBL. When we compared the results between the two groups, there was a significant difference in postoperative drainage (p=0.000). Postoperative drainage was 36.5±150.6 in the LESS-M group, but 107.8±142.3in the CLM group. Less postoperative drainage in the LESS-M group may lead to accumulation of blood in the abdominal cavity, leading to an increase in HBL.
Because HBL was different between LESS-M group and CLM group, we respectively conducted multiple linear regression analysis, to analyzed the risk factors affecting HBL. The result indicated that the BMI (p=0.047), pre-operative value of Hct (p=0.011), degeneration of largest removed leiomyoma in the uterus (p=0.003) and location of largest removed leiomyoma in the uterus (p=0.024) were risk factors in LESS-M group. And the age (p=0.046) and cell types of largest removed leiomyoma in the uterus (p=0.023) might increase the HBL in the CLM group.
Studies have shown that obesity causes greater postoperative blood loss, which might be related to deeper adipose tissue.(28) From our data combined with previous studies, we can know that higher BMI may increase HBL, however, the specific relationship remains to be further studied. Higher level of pre-operative value of Hct may be involved in the process of post-operative hyperfibrinolysis which increased accumulation of HBL in the interstitial space. (29)This statement is consistent with our conclusion and suggests that we should pay more attention to the post-operative blood changes. Miao et al. pointed out that the value of HBL was positively correlated with age in total hip arthroplasty.(30) Zhao et al. conjecture that this might be related to the loose fibrous tissue around the uterus caused by reproductive history and aging.(23)
Hsiao et al. demonstrated that the maximum myoma diameter was a risk factor for blood loss in myomectomy.(31) Our study also indicates that the largest removed leiomyoma in the uterus is a risk factor for HBL. We speculate that a larger myoma means a wider dissection area, which might lead to an increase in the bleeding area.
Our results show that the location of the largest removed leiomyoma in the uterus was also a risk factor, and the HBL of uterine body leiomyomas is higher. Although the cervical myometrium is weak and close to the blood vessels of the uterus. This may be related to the insufficient samples of cervical leiomyoma.
Moreover, according to our data, degeneration of the largest removed leiomyoma and cellular leiomyoma might increase HBL. Degenerative uterine leiomyomas are often accompanied by Uterine fibroids are often accompanied by interstitial edema and vascular morphological changes, which may cause more blood loss.(32, 33) Studies have pointed out the possibility of malignant transformation of cellular leiomyoma to leiomyosarcoma.(34) We speculate that cellular uterine fibroids may have a potential invasive capacity, thereby increasing postoperative bleeding.
However, our study still has limitations. In more in-depth studies, we need to increase the sample size and further explore how to assess TBL of patients more accurately.