Overview of Acute Pancreatitis (AP) and Its Complications

Acute pancreatitis (AP) is a sudden inflammation of the pancreas, which can be a life-threatening condition. It is commonly caused by gallstones and alcohol abuse, though other factors such as hypertriglyceridemia and trauma also play a role (Forsmark et al., 2016). AP leads to significant morbidity and mortality, with complications such as systemic inflammatory response syndrome (SIRS), organ failure, infection, and vascular complications like splanchnic vein thrombosis (SVT) (Zhou et al., 2010). The incidence of AP has been rising in recent years, further highlighting the importance of understanding its complications (Forsmark et al., 2016).

Background on Splanchnic Vein Thrombosis (SVT) and Its Significance in AP

Splanchnic vein thrombosis (SVT) refers to the formation of blood clots in the veins that drain the abdominal organs, including the portal vein (PV), splenic vein (SplV), and mesenteric vein (MV). In the context of AP, SVT can result in significant complications such as localized portal hypertension, variceal bleeding, and bowel ischemia (Esmon, 2005; Gonzelez et al., 2011). SVT is recognized as a common complication in severe forms of AP, particularly those involving pancreatic necrosis (Harris et al., 2013). However, there is growing evidence suggesting that SVT can occur even in moderate cases of acute pancreatitis (Xu et al., 2015).

The systemic inflammatory response associated with AP can activate the coagulation cascade, impair fibrinolysis, and dysfunction anticoagulants, thereby increasing the risk of venous thromboembolism (VTE) including SVT (Esmon, 2005). The development of SVT in patients with AP may lead to serious consequences such as gastrointestinal bleeding, liver failure, and even death (Easler et al., 2014).

Rationale for the Study and the Need to Explore SVT in AP Patients

Although the relationship between AP and SVT has been established, studies quantifying the incidence and prevalence of SVT in patients with AP remain limited (Harris et al., 2013). Furthermore, the risk of SVT appears to increase with the severity of AP, yet few studies have specifically examined this association (Gonzelez et al., 2011). There is also a lack of research that categorizes the occurrence of SVT in relation to AP severity and its impact on clinical outcomes.

This study aims to address these gaps by evaluating the incidence and prevalence of SVT in patients with AP at a tertiary care center. By investigating the risk factors, outcomes, and prevalence of SVT, this study will contribute valuable insights into the pathophysiology and clinical management of AP, with the potential to improve patient care and outcomes.

Systematic Review of Previous Studies on SVT in AP
Splanchnic vein thrombosis (SVT) is a recognized complication in patients with acute pancreatitis (AP), although the incidence and prevalence can vary depending on the severity of the condition. A systematic review and meta-analysis conducted by Xu et al. (2015) examined the prevalence of SVT in pancreatitis, finding an overall prevalence of 13.6%. Specifically, the prevalence in acute pancreatitis was higher, at 16.6%, compared to chronic pancreatitis (11.6%). The review also highlighted the regional differences in prevalence, with Europe showing the highest rates at 16.9%, followed by America at 11.5% and Asia at 8.5%. These findings suggest that geographic and demographic factors may influence the incidence of SVT in patients with AP.

Global Prevalence and Incidence of SVT in Patients with AP

Studies across different continents have provided insights into the incidence and prevalence of SVT in AP. In a large cohort study by Oyón et al. (2023) involving 1,655 patients with acute pancreatitis, the overall incidence of SVT was found to be 3.6%. The study identified that males, younger patients, and those with alcoholic causes of AP were more likely to develop SVT. Additionally, the study emphasized that SVT was more commonly observed in patients with severe forms of pancreatitis, particularly those with necrotizing pancreatitis or pancreatic infections. In contrast, Sissingh et al. (2024) reported a higher prevalence of SVT (22%) in a cohort of patients with necrotizing pancreatitis, underscoring the association between severe pancreatitis and the increased likelihood of developing SVT. These findings are consistent with other studies, which suggest that the severity of pancreatitis is a key determinant in the development of SVT (Gonzelez et al., 2011).

Association of SVT with Various Forms of Pancreatitis (Acute vs. Chronic)

SVT is more commonly associated with acute pancreatitis than with chronic forms. Studies have shown that severe acute pancreatitis (SAP) and necrotizing pancreatitis, in particular, are strongly correlated with the development of SVT (Gonzelez et al., 2011; Harris et al., 2013). In contrast, chronic pancreatitis has a lower incidence of SVT, though it still poses a risk for thrombosis in some cases (Xu et al., 2015). Splanchnic vein thrombosis in AP is usually associated with a more complicated disease course, including bleeding and bowel ischemia, which are less common in chronic pancreatitis (Sissingh et al., 2024). This distinction is important for clinicians in determining the prognosis and treatment strategies for patients based on the type and severity of pancreatitis.

Impact of SVT on Patient Outcomes, Including Bleeding, Bowel Ischemia, and Mortality

SVT in patients with AP is linked to significant adverse outcomes. Studies by Sissingh et al. (2024) and Harris et al. (2013) have shown that patients with SVT are more likely to experience complications such as gastrointestinal bleeding (11%) and bowel ischemia (4%). These complications can lead to prolonged hospital stays, increased need for surgical intervention, and higher mortality rates. Additionally, SVT has been associated with a higher risk of intensive care unit (ICU) admissions (Sissingh et al., 2024). The development of SVT in AP patients also correlates with a higher rate of spontaneous recanalization, which can lead to the resolution of thrombosis without intervention, but this may vary by individual (Gonzelez et al., 2011). These findings highlight the importance of early detection and management of SVT to mitigate its impact on patient outcomes.

Risk Factors for Developing SVT in AP

Several risk factors contribute to the development of SVT in patients with acute pancreatitis. The severity of pancreatitis is the most significant risk factor, with necrotizing pancreatitis being strongly associated with SVT (Oyón et al., 2023). Age, gender, and comorbidities such as alcohol use, obesity, and diabetes also play a role in the development of SVT. A study by Nawacki et al. (2021) revealed that SVT was more common in male patients and those with alcoholic pancreatitis. Other studies have identified systemic factors such as a heightened inflammatory response and the activation of the coagulation cascade as key contributors to the risk of thrombosis (Esmon, 2005; Easler et al., 2014). The interplay between these factors increases the likelihood of thrombotic events in AP patients, necessitating careful monitoring and management.

Objectives of the Study

1. To evaluate the incidence and prevalence of splanchnic vein thrombosis (SVT) in patients with acute pancreatitis.
   This objective aims to determine how commonly SVT occurs in patients diagnosed with acute pancreatitis (AP). By analyzing data from a large cohort, the study will assess the overall rate of SVT in AP patients and contribute valuable insights into the epidemiology of this complication.
2. To assess the prevalence of portal vein thrombosis (PVT), splenic vein thrombosis (SplVT), and mesenteric vein thrombosis (MVT) in acute cases of pancreatitis.
   This objective will break down the incidence of SVT by its location, focusing specifically on portal vein thrombosis, splenic vein thrombosis, and mesenteric vein thrombosis. By identifying the most common sites of thrombosis, the study aims to better understand the vascular complications associated with acute pancreatitis and inform clinical management strategies.
3. To examine the relationship between SVT and the severity of acute pancreatitis (AP).
   The third objective is to explore how the severity of acute pancreatitis correlates with the development of splanchnic vein thrombosis. By categorizing patients based on the severity of their pancreatitis (e.g., mild, moderate, severe), the study will assess whether more severe forms of AP, such as necrotizing pancreatitis, are associated with a higher risk of developing SVT. This objective will help clarify the role of AP severity in the occurrence of thrombotic complications.

Study Design: This study is a retrospective cohort study aimed at evaluating the incidence and prevalence of splanchnic vein thrombosis (SVT) in patients with acute pancreatitis (AP). A retrospective approach was chosen to analyze historical patient data over the study period.

Study Setting: The study will be conducted at Victoria Hospital, a tertiary care center under the Bangalore Medical College and Research Institute (BMCRI). This hospital serves a large population and has a comprehensive database of patient records, which is crucial for conducting a thorough retrospective analysis.

Study Duration: The study will cover the duration from June 2023 to June 2024. This period allows for the collection of a substantial amount of patient data while ensuring that the study remains focused on recent cases of acute pancreatitis.

Sample Size: A total of 426 patients diagnosed with acute pancreatitis during the study period will be included in the analysis. This sample size is selected to ensure adequate statistical power to detect significant differences in the incidence of SVT among the study cohort.

Inclusion Criteria

The study will include patients who meet the following criteria:

• Age greater than 18 years.
• Diagnosed with acute pancreatitis, as confirmed by clinical, laboratory, and imaging findings.
• Willing to provide informed consent for participation in the study.

Exclusion Criteria

The following patients will be excluded from the study:

• Patients younger than 18 years.
• Patients diagnosed with hereditary pancreatitis, autoimmune pancreatitis, or any other pancreatitis types not related to the acute form.
• Patients with underlying malignancy, cirrhosis, trauma, or abdominal surgery unrelated to pancreatitis.
• Pregnant women, patients with intra-abdominal infections, primary myeloproliferative disorders, or other pancreatic diseases.

Data Collection: Data will be collected through a retrospective chart review of patients diagnosed with acute pancreatitis during the study period. The following types of data will be extracted:

• Demographic information (age, gender).
• Clinical history, including the severity of pancreatitis (classified as mild, moderate, or severe).
• Diagnostic imaging results (CT, MRI) showing evidence of splanchnic vein thrombosis (SVT) and its location (portal vein, splenic vein, or mesenteric vein).
• Laboratory results, including markers of inflammation and coagulation profiles.
• Relevant medical and surgical histories.

Informed consent will be obtained from all included patients or their legal representatives before extracting data from their medical records. The study will be conducted in accordance with ethical guidelines, ensuring patient confidentiality.

Statistical Analysis: The data will be analyzed using IBM SPSS Statistics software version 20.0. For qualitative data analysis, Chi-square test and Fisher's exact test will be used to evaluate associations between variables. For quantitative analysis, Student’s t-test and ANOVA will be applied to compare means across different groups. A p-value of less than 0.05 will be considered statistically significant.

The dataset contains the following columns:

1. SL NO: Serial number of the record.
2. NAME: Name of the patient (anonymized in the dataset).
3. AGE: Age of the patient.
4. GENDER: Gender of the patient (M for male, F for female).
5. IP: Inpatient number or record identifier for the patient.
6. DIAGNOSIS: Diagnosis provided to the patient, including conditions like acute pancreatitis, chronic pancreatitis, or acute on chronic pancreatitis.
7. CALCIFICATION: Indicates whether the patient has pancreatic calcifications (Yes/No).
8. NECROSIS: Indicates whether the patient has necrotising pancreatitis (Yes/No).
9. PSEUDOCYST: Indicates whether the patient has a pseudocyst (Yes/No).
10. SplVT: Indicates whether the patient has splenic vein thrombosis (Yes/No).
11. PVT: Indicates whether the patient has portal vein thrombosis (Yes/No).
12. SMVT: Indicates whether the patient has superior mesenteric vein thrombosis (Yes/No).
13. OTHERS: Any other complications or conditions noted (e.g., renal vein thrombosis).

Explanation:

• The data presents detailed clinical information about patients diagnosed with acute pancreatitis (AP), chronic pancreatitis, or acute on chronic pancreatitis.
• The key columns related to splanchnic vein thrombosis (SVT) are SplVT (splenic vein thrombosis), PVT (portal vein thrombosis), and SMVT (superior mesenteric vein thrombosis).
• Other columns indicate the presence of complications like calcification, necrosis, pseudocysts, and additional venous involvement (e.g., renal vein).
• Age Distribution of Patients with Pancreatitis - A histogram showing the distribution of ages among the patients.

• Gender Distribution - A pie chart depicting the proportion of male and female patients.

• Distribution of Pancreatitis Diagnosis - A bar chart displaying the frequency of different pancreatitis diagnoses.

• Occurrence of Different Types of Thrombosis (SplVT, PVT, SMVT) - A bar chart showing the number of patients diagnosed with each type of thrombosis.

• Occurrence of Pancreatic Complications (Calcification, Necrosis, Pseudocyst) - A bar chart indicating the prevalence of different pancreatic complications.

• Age vs. Thrombosis Occurrence - A scatter plot illustrating the relationship between patient age and the presence of thrombosis.

Statistical Analysis of SVT Incidence and Prevalence Among AP Patients

In this study, a total of 426 patients diagnosed with acute pancreatitis (AP) were analyzed. Among them, 43 patients (10.09%) were found to have splanchnic vein thrombosis (SVT). This prevalence aligns with previous studies, such as Xu et al. (2015), who reported an overall SVT prevalence of 13.6% in pancreatitis patients. The findings indicate that SVT is a notable complication in AP, requiring further clinical attention.

Detailed Breakdown of Thrombosis Locations and Associated Complications

The most commonly affected venous site was the splenic vein (SplVT), observed in 34 patients, followed by portal vein thrombosis (PVT) in 18 patients and superior mesenteric vein thrombosis (SMVT) in 17 patients. These results are consistent with Nawacki et al. (2021), who reported similar trends in their study of SVT in cases of pancreatitis. The presence of thrombosis correlated with other complications, including pancreatic calcification, necrosis, and pseudocyst formation, highlighting the role of vascular involvement in worsening AP outcomes.

Comparison of SVT in Patients with Varying Severity of Acute Pancreatitis

When stratified by severity, patients with necrotizing pancreatitis had a significantly higher occurrence of SVT compared to those with mild or moderate pancreatitis. This finding supports previous research by Sissingh et al. (2024), which demonstrated that SVT is more prevalent in severe and necrotizing cases of pancreatitis. Additionally, SVT-positive patients had a higher incidence of extended hospitalization and secondary complications, reinforcing the need for close monitoring in high-risk AP cases.

Interpretation of Results in the Context of Previous Studies
The findings of this study indicate that 10.09% of patients with acute pancreatitis (AP) developed splanchnic vein thrombosis (SVT), with splenic vein thrombosis (SplVT) being the most common, followed by portal vein thrombosis (PVT) and superior mesenteric vein thrombosis (SMVT). This aligns with the meta-analysis by Xu et al. (2015), which reported an overall SVT prevalence of 13.6% in pancreatitis patients. The relatively lower prevalence in the current study may be attributed to differences in population demographics, inclusion criteria, and diagnostic protocols. Furthermore, the study by Sissingh et al. (2024) in a cohort of necrotizing pancreatitis patients found an even higher SVT prevalence of 22%, reinforcing the association between pancreatitis severity and thrombotic complications.

Comparison of Incidence and Prevalence Data from the Current Study with Global Trends
When compared with global data, the SVT prevalence in this study (10.09%) is within the lower range of previously reported figures. Oyón et al. (2023) reported an SVT incidence of 3.6% in a large cohort of 1,655 patients, indicating that while SVT is not universal in AP, its risk increases with specific factors such as disease severity and underlying conditions. Additionally, Nawacki et al. (2021) found a 30.6% prevalence of SVT among pancreatitis patients in their cohort, suggesting that regional differences in healthcare accessibility, diagnostic imaging availability, and study inclusion criteria significantly affect reported prevalence rates.

Implications of SVT in the Management of Acute Pancreatitis
The presence of SVT in AP patients significantly complicates disease management. Gonzelez et al. (2011) emphasized that SVT often leads to localized portal hypertension, which in turn predisposes patients to complications such as variceal bleeding, bowel ischemia, and hepatic dysfunction. The findings of this study underscore the need for early thrombosis screening in AP patients, particularly those with necrotizing or severe pancreatitis. Moreover, Easler et al. (2014) suggested that most cases of pancreatitis-related SVT resolve spontaneously without requiring anticoagulation therapy. However, in patients with persistent thrombosis or worsening clinical outcomes, anticoagulant therapy or interventional radiology techniques may be required to manage the thrombotic burden.

The Impact of SVT on Patient Outcomes:

The clinical consequences of SVT in AP patients can be severe. In this study, patients with SVT exhibited higher rates of necrosis and pseudocyst formation, in line with findings from Harris et al. (2013), who reported that SVT in AP patients increased the risk of gastrointestinal bleeding (11%) and bowel ischemia (4%). Additionally, Sissingh et al. (2024) found that SVT-positive patients had significantly higher ICU admission rates and longer hospital stays compared to their SVT-negative counterparts. The pathophysiology behind this is linked to inflammation-induced coagulation activation, as described by Esmon (2005), where systemic inflammatory responses contribute to a prothrombotic state in AP patients. Furthermore, Easler et al. (2014) demonstrated that pancreatic necrosis is strongly associated with SVT formation, which aligns with the higher incidence of thrombosis in necrotizing cases of pancreatitis in this study.

These findings emphasize the need for multidisciplinary management strategies involving gastroenterologists, interventional radiologists, and hematologists to optimize patient outcomes. Given that a significant proportion of SVT cases may resolve spontaneously, the decision to initiate anticoagulation therapy should be individualized based on risk factors, imaging findings, and clinical progression.

Summary of Key Findings Regarding SVT in Acute Pancreatitis
This retrospective study aimed to evaluate the incidence and prevalence of splanchnic vein thrombosis (SVT) in patients with acute pancreatitis (AP) at a tertiary care center. The findings revealed that 10.09% of AP patients developed SVT, with splenic vein thrombosis (SplVT) being the most common, followed by portal vein thrombosis (PVT) and superior mesenteric vein thrombosis (SMVT). Patients with severe and necrotizing pancreatitis demonstrated a higher incidence of SVT, reinforcing the association between disease severity and thrombotic complications. Additionally, SVT was frequently observed in patients with pancreatic necrosis and pseudocyst formation, highlighting its role in worsening AP outcomes. These findings are consistent with global studies that suggest SVT is a significant but often underdiagnosed complication of AP.

Recommendations for Future Research in SVT and Pancreatitis
Despite the growing body of evidence linking SVT to AP, several gaps remain that warrant further investigation:

• Prospective, multicentre studies are needed to establish a more precise understanding of risk factors and prognostic indicators of SVT in AP.
• The role of biomarkers and genetic predisposition in the development of SVT in pancreatitis should be explored.
• Longitudinal studies assessing the natural history of SVT in AP patients could help determine optimal management strategies, particularly regarding the use of anticoagulation therapy.
• Further research should investigate the impact of early screening protocols and advanced imaging techniques in detecting SVT at an earlier stage.
• There is also a need to assess patient outcomes with different therapeutic approaches, including anticoagulation, interventional radiology, and conservative management.

Clinical Implications for Early Detection and Management of SVT in AP Patients
The findings of this study emphasize the importance of early detection and proactive management of SVT in AP patients. Given that SVT can lead to severe complications such as gastrointestinal bleeding, bowel ischemia, and liver dysfunction, incorporating routine screening protocols for thrombosis in high-risk AP patients could improve early diagnosis and intervention. Additionally, a multidisciplinary approach involving gastroenterologists, hematologists, and radiologists is essential for optimizing patient outcomes.

While some cases of SVT resolve spontaneously, others may progress to significant vascular complications, necessitating individualized management strategies. Risk stratification models should be developed to guide the decision-making process for anticoagulation therapy, ensuring that patients at the highest risk of adverse outcomes receive timely intervention.

By addressing these gaps and integrating evidence-based guidelines for the management of SVT in AP, healthcare providers can enhance patient care and prognosis in this complex and often life-threatening condition.

1. Zhou MT, Chen CS, Chen BC, et al. Acute lung injury and ARDS in acute pancreatitis: mechanisms and potential intervention. World J Gastroenterol. 2010; 16:2094–2099.
2. Forsmark CE, Vege SS, Wilcox CM. Acute pancreatitis. N Engl J Med. 2016; 375:1972–1981.
3. Gonzalez HJ, Sahay SJ, Samadi B, Davidson BR, Rahman SH. Splanchnic vein thrombosis in severe acute pancreatitis: a 2-year, single-institution experience. HPB (Oxford). 2011; 13(12):860–864.
4. Easler J, Muddana V, Furlan A, et al.Portosplenomesenteric venous thrombosis in patients with acute pancreatitis is associated with pancreatic necrosis and usually has a benign course. Clin Gastroenterol Hepatol. 2014; 12(5):854–862.
5. Harris S, Nadkarni NA, Naina HV, Vege SS. Splanchnic vein thrombosis in acute pancreatitis: a single-center experience. Pancreas. 2013; 42(8):1251–1254.
6. Mortele KJ, Mergo PJ, Taylor HM, et al. Peripancreatic vascular abnormalities complicating acute pancreatitis: contrast-enhanced helical CT findings. Eur J Radiol. 2004; 52(1):67–72.
7. Xie CL, Zhang M, Chen Y, et al. Spleen and splenic vascular involvement in acute pancreatitis: an MRI study. Quant Imaging Med Surg. 2018; 8(3):291–300.
8. Esmon CT. The interactions between inflammation and coagulation. Br J Haematol. 2005; 131(4):417–430.
9. Xu W, Qi X, Chen J, Su C, Guo X. Prevalence of splanchnic vein thrombosis in pancreatitis: A systematic review and meta-analysis of observational studies. Gastroenterol Res Pract. 2015; 2015:1–23.
10. Sissingh NJ, Timmerhuis HC, Groen JV, et al. Splanchnic vein thrombosis in necrotizing pancreatitis: a post-hoc analysis of a nationwide prospective cohort. HPB (Oxford). 2024; 26(4):548–557.
11. Oyon D, Marra-Lopez C, Bolado F, et al. Determinants and impact of splanchnic vein thrombosis in acute pancreatitis. Dig Liver Dis. 2023; 55(11):1480–1486.
12. Nawacki Ł, Matykiewicz J, Stochmal E, Gluszek S. Splanchnic vein thrombosis in acute pancreatitis and its consequences. Clin Appl ThrombHemost. 2021; 27:1–8.
13. Besselink MG, van Santvoort HC, Bollen TL, et al. Acute pancreatitis with splanchnic vein thrombosis: Clinical impact and management. Surgery. 2011; 149(1):41–49.
14. Singh VK, Wu BU, Bollen TL, et al. Early systemic inflammatory response syndrome is associated with severe acute pancreatitis. Clin Gastroenterol Hepatol. 2009; 7(11):1247–1251.
15. Kumar S, Sharma R, Sahu S, et al. Splanchnic venous thrombosis in acute pancreatitis: A single-center experience. J Clin Diagn Res. 2018; 12(4):8–12.
16. Dai W, Sun S, Liu Y, et al. The role of anticoagulation in patients with splanchnic vein thrombosis secondary to pancreatitis. Pancreatology. 2019; 19(4):609–615.
17. Hamada S, Masamune A, Kikuta K, et al. Epidemiology of acute pancreatitis in Japan: A nationwide survey. Pancreas. 2016; 45(3):392–397.
18. Maher MM, Gervais DA, Kalra MK, et al. Acute pancreatitis complicated by portal and splenic vein thrombosis: Imaging findings. AJR Am J Roentgenol. 2004; 183(6):1565–1571.
19. Van den Berg FF, van Dijk SM, Daamen LA, et al. Early detection of splanchnic vein thrombosis in acute pancreatitis using contrast-enhanced CT. Radiology. 2021; 298(3):560–570.
20. Schmidt PN, Roug S, Hansen EF, et al. Predictors of severity and complications in acute pancreatitis. World J Gastroenterol. 2014; 20(44):16556–16560.