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 Table of Contents  
Year : 2023  |  Volume : 14  |  Issue : 2  |  Page : 157-162

Assessment of postoperative venous thromboembolic complications

Department of Surgery, Faculty of Medicine; Department of Surgery, King Abdulaziz University Hospital, Jeddah, Saudi Arabia

Date of Submission31-May-2023
Date of Decision10-Jun-2023
Date of Acceptance20-Jun-2023
Date of Web Publication27-Jul-2023

Correspondence Address:
Mohammed F Alhazmi
Department of Surgery, Faculty of Medicine, King Abdulaziz University, Jeddah, Saudi Arabia. Department of Surgery, King Abdulaziz University Hospital, Jeddah
Saudi Arabia
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/joah.joah_35_23

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BACKGROUND: Postoperative venous thromboembolic events (VTEs) are a preventable cause of death. Adherence to available guidelines and prophylactic measures is suboptimal. This study examined postoperative VTEs prevalence, prophylaxis guideline adherence, and VTEs risk factors among surgical patients at King Abdulaziz University Hospital in Saudi Arabia.
METHODOLOGY: This retrospective study analyzed VTEs patients from August 2020 to November 2022. Medical records collected data on patients, procedures, prevention, guideline adherence, and VTEs diagnosis. The statistical analysis evaluated the link between prophylactic measures and VTEs occurrence.
RESULTS: Thirty-one (32%) of the 97 VTEs diagnosed in patients were postoperative VTEs. Mortality rates were 18.5%, and for postoperative VTEs patients were 12.9%. Most patients (87.1%) were at high risk (Caprini score ≥ 5) for VTEs. Abdominopelvic procedures were 64.5% of cases. Approximately 60% of patients received postoperative prophylaxis. Enoxaparin was the most frequently used prophylaxis method (63.1%). Mechanical prophylaxis was used in 36.8% of patients who received prophylaxis. Compliance for extended prophylaxis was only 10.5%. Late initiation of prophylactic measures was significantly associated with deep vein thrombosis occurrence.
CONCLUSION: The study emphasizes the need to follow prophylaxis guidelines. Improving compliance with prophylactic measures, especially for high-risk patients, can potentially reduce postoperative VTEs.

Keywords: Deep vein thrombosis, postoperative venous thromboembolic events, pulmonary embolism, thromboprophylaxis, venous thromboembolism

How to cite this article:
Aljiffry MM, Alhazmi MF. Assessment of postoperative venous thromboembolic complications. J Appl Hematol 2023;14:157-62

How to cite this URL:
Aljiffry MM, Alhazmi MF. Assessment of postoperative venous thromboembolic complications. J Appl Hematol [serial online] 2023 [cited 2023 Sep 27];14:157-62. Available from: https://www.jahjournal.org/text.asp?2023/14/2/157/382413

  Introduction Top

Venous thromboembolic events (VTEs) are a significant cause of preventable death among hospitalized patients. Postoperative venous thromboembolism events refer to the occurrence of thrombotic phenomena following surgical procedures. This condition can manifest as either deep vein thrombosis (DVT) or pulmonary embolism (PE).[1] DVT manifests in the deep veins of the lower extremities, whereas PE arises from the occlusion of the pulmonary artery by a blood clot, impeding blood circulation in the pulmonary region.

The likelihood of developing postoperative VTEs is significantly influenced by the nature of the procedural intervention.[2] The global occurrence of symptomatic postoperative VTEs is reported to be 8%.[1] The incidence of symptomatic VTEs in postoperative patients in Saudi Arabia has been estimated to be 0.64%. However, this figure is believed to be an underestimate and further studies are needed to confirm this.[3],[4] The implementation of postoperative thromboembolic prophylaxis has been shown to significantly decrease the likelihood of developing VTEs.[5] The incidence of DVT and PE can reach up to 40%–60% and 25%, respectively, in the absence of prophylactic measures.[5] The administration of prophylaxis has been shown to significantly decrease the aforementioned percentages to 10%–40% and 1.5%, respectively.[5] In 2012, the American College of Chest Physicians (ACCP) updated its guidelines for the prevention of postoperative thromboembolism. The revised guidelines incorporate risk stratification through the utilization of the Caprini score for diverse surgical populations, alongside recommendations for prophylactic measures. Various measures can be employed to prevent VTEs, including pharmacological interventions such as low-molecular-weight heparin, unfractionated heparin (UFH), fondaparinux, or aspirin, as well as mechanical interventions such as early ambulation, intermittent pneumatic compression (IPC), inferior vena cava (IVC) filters, or graduated compression stockings (GCS).[6] Pharmacological prophylaxis is commonly advised for major procedures, whereas mechanical techniques are favored for patients who exhibit risk factors for bleeding.[6]

Despite the existence of established protocols and guidelines, a significant number of healthcare providers do not adhere to the recommended postoperative prophylaxis for VTEs.[5],[7] Recent research conducted in Saudi Arabia has revealed that approximately half of the eligible surgical patients are administered prophylaxis.[5],[7]

The objective of this study was to examine the prevalence of postoperative venous thromboembolic complications among patients diagnosed with VTEs and the extent to which prophylaxis guidelines are being followed among surgical patients at King Abdulaziz University Hospital (KAUH) in Saudi Arabia. Moreover, the study had the objective of identifying the risk factors linked to postoperative VTEs in this particular population. To enhance our comprehension of the efficacy of preventive measures in clinical settings, a retrospective analysis was carried out at KAUH in Jeddah, Saudi Arabia.

  Methodology Top

Study design

This retrospective study was conducted at KAUH, which is a tertiary care hospital located in Jeddah, Saudi Arabia. Data were collected from the electronic medical records of patients who were diagnosed with VTEs from August 2020 to November 2022. Subsequently, the prevalence of patients who underwent procedures and were diagnosed with VTEs was calculated and VTEs postoperative prophylactic therapy was studied. All patients who were diagnosed with VTEs within 3 months after the procedure during the study period were included in the study. Patients under the age of 18 years or with incomplete data were excluded from the study.

Ethical approval was obtained from the Unit of Biomedical Ethics at King Abdulaziz University (Reference Number: 44-23). The Institutional Review Board waived the requirement for informed consent since this was a retrospective study and patient data were anonymized to protect their privacy.

Data collection

Data were collected from the electronic medical records of patients who met the inclusion criteria. The study collected data on patient demographics, including age, sex, and comorbidities. Procedural details such as the type and duration of the procedure and the Caprini score were also recorded. In addition, the type of postoperative prophylactic measures received (pharmacological or mechanical), duration of prophylaxis, compliance with the ACCP guidelines, and the type and timing of VTEs diagnosis were documented. Imaging studies used for VTEs diagnosis were also noted.

Statistical analysis

Data were extracted using a specially designed data sheet that met the study's objectives. The extracted data were stored in a protected computer's Excel spreadsheet to ensure patient confidentiality. Data were analyzed using IBM SPSS version 25 (IBM corp. NY, USA). Descriptive statistics, such as the mean, median, and standard deviation (SD), were utilized to summarize the continuous variables. Categorical variables are typically summarized by their frequencies and percentages. The Chi-square test, Fisher's test, and confidence interval (CI) were used to evaluate the association between prophylactic measures and the occurrence of VTEs. A significance level of P < 0.05 was used for two-tailed tests.

  Results Top

Patients' demographics

Ninety-seven patients were diagnosed with confirmed VTEs between August 2020 and November 2022, with a total mortality rate of patients diagnosed with medical or postoperative VTEs was 18.5%. Out of all the patients with VTEs, 31 (32%) were diagnosed with postoperative VTEs. The outcomes of hospitalization for patients with postoperative VTEs indicate that 87.1% were discharged, while 12.9% of postoperative VTEs patients died. The primary causes of death were circulatory failure (75%) and respiratory failure (25%). In terms of gender distribution, 41.9% of the patients were males, and 58.1% were females. The mean ± SD age of the patients was 62.8 ± 17.3 years, and they were categorized into various groups, which are represented in [Table 1]. Various risk factors for VTEs have been identified in patients who developed postoperative VTEs. The most prevalent risk factors and prophylactic measures for each risk factor are presented in [Table 1]. Although less common, there were other risk factors identified among the postoperative patient population. These included chronic obstructive pulmonary disease (6.5%), pregnancy or postpartum status (6.5%), a history of unexplained or recurrent spontaneous abortion (6.5%), hip, pelvis, or leg fractures (6.5%), inflammatory bowel disease (3.2%), factor V Leiden (3.2%), anticardiolipin antibodies (3.2%), and a history of stroke (3.2%).
Table 1: Demographics and prophylaxis in surgical patients

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Risk assessment

The Caprini score is a widely recognized risk assessment tool used to predict the likelihood of VTEs in hospitalized patients. Caprini risk assessment model is represented in [Table 2]. We found that the majority of patients (87.1%) were at high risk (with a Caprini score of ≥ 5) for developing VTEs, while the remaining patients (12.9%) had a moderate risk (with a Caprini score of 3–4). The mean ± SD of Caprini score was 9.9 ± 4.6. We divided the Caprini scores into four groups based on their values: 3–4, 5–6, 7–8, and 9 or higher. The majority of patients (61.3%) were classified in the group with a score of 9 or higher, indicating a very high risk of developing VTEs with a 10.7% risk. This was followed by 19.4% of patients who had a score of 7–8, indicating a 4% risk of developing VTEs. Subsequently, 6.5% of patients had a stratified score of 5–6, indicating a 1.8% risk of developing VTEs. Finally, 12.9% of patients were classified as having a moderate risk (3–4), indicating a 0.7% chance of developing VTEs.[8]
Table 2: Caprini risk assessment mode

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Imaging modalities

The imaging modalities used to aid in the diagnosis of VTEs include Doppler ultrasound, chest radiography, computed tomography (CT) angiography, abdominal CT, chest CT, magnetic resonance imaging (MRI), and abdominal ultrasound. Doppler ultrasound was the most commonly used imaging modality, accounting for 45.2% of cases. Chest X-rays and CT angiograms were used in 22.6% of cases, followed by abdominal CT scans in 9.7% of cases. Chest CT and MRI were performed in 6.5% and 3.2% of cases, respectively. Abdominal ultrasound was used in only 3.2% of the cases.

Types of procedures

Regarding procedures, 64.5% of the patients underwent abdominopelvic procedures, such as exploratory laparotomy, abdominal hysterectomy, and urethroplasty. The remaining 35.5% underwent nonabdominopelvic procedures, such as femoral artery embolectomy, repair of extremity aneurysms, reduction of a dislocated hip, and excisional debridement of soft tissue. Of all the procedures performed, 64.5% were classified as minor procedures. A significant number of patients who did not receive postoperative VTEs prophylaxis underwent minor procedures (91.6%) (P < 0.05). Meanwhile, 29% of the procedures were classified as major. Of patients who underwent major procedures, the vast majority of patients (89%) received postoperative prophylaxis. Only 3.2% of the procedures performed were laparoscopic, while an additional 3.2% were elective arthroplasty procedures. The procedures vary in invasiveness, ranging from minimally invasive to highly invasive. The percentage of postoperative patients who received postoperative prophylaxis and those who did not receive it for each procedure are shown in [Figure 1].
Figure 1: Comparison of postoperative prophylaxis: percentage of patients with and without prophylaxis for each procedure

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Utilization of postoperative prophylaxis

Of the patients included in the study, approximately 60% received postoperative prophylaxis, while 40% did not receive any treatment. Among the patients who received prophylaxis, 94.7% were given pharmacological prophylaxis, with a mean of 11.3 ± 9.077 days, while 36.8% received mechanical prophylaxis for an average of 3 ± 1.870 days. Pharmacological types and doses are represented in [Table 3]. The most frequently utilized pharmacological prophylaxis was enoxaparin, which was administered to 63.1% of the patients who received prophylaxis for 1–30 days. This was followed by a low dose of UFH, which was administered to 15.8% of the patients for 4–14 days. Warfarin was prescribed for prophylaxis to 15.8% of the patients for long-term therapy. In addition, one patient was prescribed long-term therapy with Apixaban. Out of the patients who received pharmacological prophylaxis, only 11.1% of patients have received extended pharmacological prophylaxis (4 weeks). Mechanical prophylaxis was administered to 36.8% of the patients for 1–5 days. Among the patients who received prophylaxis, early ambulation was the most frequently utilized method, accounting for 26.3% of cases. IPC was utilized in 10.5% of the patients who received prophylaxis, followed by IVC and GCS, which were each used in 5.2% of patients. Of those who received prophylaxis, 79% received a single therapy, while 21% received combination therapy.
Table 3: Prophylaxis and prevalence of deep vein thrombosis and pulmonary embolism

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Postoperative venous thromboembolic events

The most common VTE event was DVT, which was diagnosed in 64.5% of the patients. Patients with DVT developed it on a mean of 44.8 ± 28.3 days. PE was observed in 19.4% of the patients, with a mean onset of 22.5 ± 19.9 days postoperatively. DVT progressed to PE in 16.1% of the patients, with an average onset of 24.6 ± 13.9 days postoperatively. We found that patients who developed postoperative DVT had a later initiation of pharmacological therapy compared to patients who did not develop postoperative DVT (mean ± SD, 1.514 ± 0.655; 95% CI: 0.063–2.965; P < 0.05). There was no significant difference in therapy initiation between patients who developed PE and those whose DVT progressed to PE (P > 0.05). Notably, a large majority of patients who developed VTEs did so after being discharged from the hospital (80.6%), whereas the remaining cases occurred during hospitalization (19.4%) (P < 0.05).

  Discussion Top

Despite the presence of established protocols and guidelines, health-care providers often neglect to administer appropriate prophylaxis for postoperative care.[3],[4] Of the 31 postoperative patients, 64.5% underwent minor procedures. The study yielded that a significant proportion of patients who did not receive postoperative prophylaxis had undergone minor procedures (91.6%) (P < 0.05). Conversely, a substantial proportion of patients who underwent major procedures were administered prophylaxis (89%). The findings of this study suggest that there is a lack of emphasis on administering suitable prophylactic measures following minor procedures. Despite the limited research available on the association between postoperative VTEs and minor procedures, a study published in 2022 has shown that minor procedures can elevate the risk of VTEs by 3.5 times.[9] An additional consideration in the development of postoperative VTEs following minor procedures is the interplay between the patient's individual risk factors and the type of procedure performed. The likelihood of VTEs is influenced by both of these factors. Hence, it is imperative to prioritize the attention given to the patient's individual risk factors and refrain from neglecting the minor procedural risks that are linked to the occurrence of postoperative VTEs. This approach will aid in reducing the incidence of VTEs and improving patient outcomes.

Of all the patients who developed postoperative VTEs, approximately 60% did receive postoperative VTEs prophylaxis, while the remaining 40% did not receive any prophylaxis. The present findings suggest that a considerable proportion of eligible patients did not receive VTEs prophylaxis, which aligns with previous studies conducted in Saudi Arabia, reporting that half of the eligible patients do not receive prophylaxis.[5],[7] Furthermore, a study conducted in Singapore has demonstrated a similar problem, where only 89.8% of individuals who underwent procedures were not administered postoperative prophylaxis for VTEs.[10] Furthermore, pharmacological prophylaxis is employed more frequently (89.4%) than mechanical methods (36.8%). The preferred methods for postoperative prophylaxis are enoxaparin and early ambulation. Despite the proven effectiveness and widespread recognition by the ACCP and the American Society of Hematology in reducing postoperative VTEs without the risk of bleeding, the underutilization of mechanical prophylaxis may have significantly contributed to the development of VTEs.[6],[11] Another potential contributing factor to the occurrence of postoperative VTEs is the emphasis on early ambulation as the primary form of mechanical prophylaxis. However, this approach is insufficient in mitigating the likelihood of VTEs due to various contributing factors. For example, certain patients may experience immobility following procedures, and despite being mobilized, a considerable proportion of patients still develop VTEs. Furthermore, it has been demonstrated that early ambulation does not effectively mitigate the venous stasis element of Virchow's triad, as evidenced by studies.[12],[13] Therefore, it is recommended that patients at moderate and high risk of thromboembolism receive more effective mechanical prophylaxis, such as IPC and GCS, in combination with pharmacological prophylaxis as suggested by the ACCP.[6],[12],[13] However, it appears that these measures were not utilized frequently enough. In addition, the deferred commencement of pharmacological treatment may have played a role in the onset of DVT. This is indicated by the results that patients who experienced postoperative DVT had a delayed initiation of pharmacological therapy compared to those who did not develop DVT (mean ± SD, 1.514 ± 0.655; 95% CI: 0.063–2.965; P < 0.05). The prompt initiation of therapy following medical procedures is considered a critical factor in mitigating the occurrence of VTEs in clinical settings.

The results indicate that a substantial proportion of patients who experienced VTEs did so following their discharge from the hospital after the procedure (80.6%), with the remaining cases occurring during their hospital stay (19.4%) (P < 0.05). Consistent with prior research, it has been demonstrated that patients who experienced postoperative VTEs were less likely to receive postoperative prophylaxis after being discharged from the hospital.[14] The limited duration of postoperative VTEs prophylaxis therapy may have been influenced by multiple factors. Several studies have demonstrated the efficacy of extended postoperative prophylaxis in preventing complications associated with VTEs,[15],[16],[17] particularly in cancer patients.[18] Therefore, it is recommended to use extended prophylaxis instead of short-term therapy. The risk of VTEs persists for a period of up to 90 days following a medical procedure, as evidenced by studies.[15],[16],[17] However, the percentage of patients who received extended pharmacological prophylaxis after postoperative prophylaxis was only 10.5%. Nonadherence to postoperative VTES prophylaxis can potentially escalate the risk of VTEs postdischarge, posing a significant healthcare challenge.[18]

None of the patients that developed postoperative VTEs received appropriate prophylaxis. The patients were subjected to either short-term pharmacological and mechanical prophylaxis or a delayed initiation of treatment. Alternatively, most postoperative patients were administered pharmacological prophylaxis exclusively, while others were given delayed or short-term prophylaxis. Only three patients received prophylaxis that was close to being appropriate. One patient was administered a daily dose of enoxaparin in conjunction with IVC therapy; however, the prophylactic measurement was discontinued after only 6 days. The patient received a diagnosis of DVT subsequent to undergoing a significant major procedure for hernia repair. The administration of enoxaparin with IPC was observed in the prophylactic measurement of two additional patients. One patient received the prophylactic measurement for 2 days, while the other received it for 6 days. However, both patients experienced a delay in the initiation of the prophylaxis.

The study has several limitations, including its retrospective design and the fact that it was conducted at a single center, which limits the generalizability of the findings to other healthcare settings. We recommend conducting a prospective study with a larger sample size.

  Conclusion Top

Postoperative VTEs complications pose a significant risk of morbidity and mortality. One-third of patients diagnosed with VTEs were postoperative, highlighting the need to prevent this avoidable complication. Most patients were classified as high-risk based on their Caprini scores. Many patients had VTEs after being discharged following procedures. Prophylaxis utilization was inadequate, particularly in regard to the use of mechanical prophylaxis and extended prophylaxis protocol. Health-care providers need education and support to follow customized preventive measures based on both patient risk factors and surgical procedures.

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Conflicts of interest

There are no conflicts of interest.

  References Top

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  [Table 1], [Table 2], [Table 3]


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