Analysis of deep venous thrombosis after Gynecological surgery: A clinical study of 498 cases

Objectives: To find out the clinical characteristics and risk factors for deep venous thrombosis (DVT) after gynecological surgery. Methods: Four hundred and ninety-eight patients treated surgically in the department of gynecology of our hospital from July 2012 to May 2014 were reviewed retrospectively. The data including patient age, gender, medical history, hospital stay, anesthesia type, operation time, occupation type, operative or postoperative medicine, perioperative bleeding, postoperative activity time, mortality rate and so on, were collected. Results: Among 498 patients, 58 were included in the thrombosis group, 423 patients in the non-thrombosis group and 17 patients were excluded. The incidence of deep venous thrombosis was 11.6%. In 58 cases with deep venous thrombosis, 6 cases developed pulmonary embolism and two patients died, the mortality rate for pulmonary embolism is 33.3%. In multivariate analysis, age, malignant tumor, cardiovascular comorbidity and postoperative hemostatics dose are independent risk factors, physical labour and minimally invasive surgery are protective factors for DVT. Conclusion: The patients with elder age, malignant tumor, cardiovascular comorbidity or large postoperative hemostatics dose should be paid high attention to and the minimally invasive surgery are optimal treatment in preventing DVT.

the fatal complication has been paid high attention in the gynecological department.
Although the perioperative low molecular weight heparin (LMWH) applying in patient undergoing gynecological surgery completely eliminated DVT and PE incidence, 1 DVT still occur after the gynecological surgery. In addition, the clinical diagnosis of DVT is notoriously inaccurate, with only 50% of cases being detected on the basis of signs and symptoms. 6 The missed diagnosis often occurred and the early and accurate diagnosis were challenging in clinical practice. Subsequently, it is critical for gynecological surgeons to learn the clinical characteristics of DVT and risk factors related to DVT after gynecological surgeries. However, up to now, few clinical studies have been published on the issues in English literatures.
Therefore, in the current study, we retrospectively reviewed 498 patients treated using gynecologic surgery between July 2012 and May 2014. The aim of the current study was to find out the clinical characteristics and risk factors of DVT after gynecologic surgery, to help surgeons better understand and prevent the fatal complication during perioperative periods.

METHODS
Four hundred and ninety-eight patients treated surgically in the department of gynecology of our hospital from July 2012 to May 2014 were reviewed retrospectively. The data including patient age, gender, medical history, hospital stay, anesthesia type, operation time, occupation type, operative or postoperative medicine, perioperative bleeding, postoperative activity time, mortality rate and so on, were collected.
The diagnosis of DVT was determined as clinically suspected DVT or PE confirmed by imaging and requiring therapeutic anticoagulation or resulting in death. Patients who had a recent DVT diagnosed prior to surgery and those who developed arterial thrombosis were excluded from the current study 5 which was approved by the ethics committee of our hospital.
Statistical analysis was performed using SPSS 19.0 (SPSS Inc., Chicago, IL, USA). Independent 2-sample t test was carried out to compare the difference of measurement data, and a chi-square test were used to compare the difference of enumeration data between two groups. Univariate and multivariate logistic regression analysis were carried out to find the correlation between variables and DVT, and the multivariate logistic regression analysis was used to determine the independent risk factors for DVT. A probability value of < 0.05 was considered to indicate statistical significance.

RESULTS
Among 498 patients, 58 were diagnosed as DVT and included in the thrombosis group, 423 patients were included in the non-thrombosis group and 17 patients were excluded from the current study. The incidence of DVT was 11.6%. In 58 cases with DVT, 6 cases developed PE and two patients died. The mortality rate for PE is 33.3%.
Among 58 cases, 11 were uterine fibroids, 13 were uterine adenomyoma, 14 were ovarian tumors, 10 were cervical cancer and 10 were ectopic pregnancy. The average age was 49.5 years old, ranged from 29 to 66 years old. The DVT occurred in fibular veins, calf muscular veins or posterior tibial veins, among which 17 cases in left lower extremity, 23 in right lower extremity and 18 in both lower extremities.
In the current study, the comparison of the clinical characteristics between the two groups are listed in Table-I. There was significant difference in age, cardiovascular comorbidity, surgical mode, occupation type, number of malignant  (Table-II).

DISCUSSION
It is reported in the United States that two million people suffered from DVT each year and 600000 progresses to PE, in which 200000 were fatal. 7 Venous thromboembolism is a major cause of morbidity and mortality in the world. In the current study, we performed a retrospective analysis of patients receiving gynecologic surgery, to determine the risk factors of DVT after surgery, to the best of our knowledge, few studies have been published on the issues.
Many studies advocated that DVT is related closely to injury of vessel wall, slowing of blood flow and blood hypercoagulation. 2 Gynecologic surgery leads to a high risk of DVT, which may be attributed to many factors. The walls of pelvic veins are thin and the veins of rectum, bladder and the reproductive system are interlinked, resulting in the pelvic venous congestion and blood flow slowing. In addition, the anaesthesia during operation may cause venous distension and the long bed rest period after surgery may affect adversely the hemodynamics of the patients, aggravating the slowing of blood flow. The trauma resulted from operation also cause blood hypercoagulation negatively, and subsequently gynecologic surgery lead to the formation of DVT. 2 The abovementioned reasons for the formation of DVT after gynecologic surgery has been confirmed by many authors. 2,4,5 In the current study, the incidence of DVT after gynecologic surgery was 11.6%, lower than that reported by Liu, but close to that reported by Santoso. 3,4 The relatively lower incidence may be attributed to the use of perioperative low molecular weight heparin (LMWH) in some patients. However, the mortality rate for PE in patients after gynecological surgery is as high as 33.3% in the current study. We found in some PE patients, the clinical symptoms are not so severe that the diagnosis of PE was neglected, which may be an explanation for the relatively high mortality rate of PE in the current study. However, in the two patients who died, PE occurred so suddenly that the rescues efforts were not successful. As a result, we suggest the fatal complication and its risk factors should be paid high attention to in patients receiving gynecological surgery, and detailed physical examination including imageological examination is critical.
Moreover, we found the elder age, malignant tumor, cardiovascular comorbidity, laparotomy operation and postoperative hemostatics dose were independent risk factors for the formation of DVT. In our opinion, these factors may be closely associated with the blood hyperagulation status, longer operation time, longer bed rest, more blood loss and more severe surgical strike, which surely aggravate the risk of DVT. In addition, we found the physical labour is a protective factor for DVT. In literatures, Yang 8 , Li 9 and Liu 10 also focused on the issues and concluded the similar conclusion. Different from the above mentioned studies, we found the minimally invasive surgery is also a protective factor in preventing the occurrence of DVT. Gynecologic laparoscopy has been regarded as a low-risk procedure for postoperative DVT, 11 which was associated with shorter operation time, less blood loss and minimal surgical strike. In the current study, the rate of DVT in patients receiving laparoscopy treatment was significantly lower. Consequently, we suggest that the minimally invasive surgery is a better option for patients in gynecology department.