Preoperative Cross-Sectional Area and Thickness of Pancreatic Stump as Possible Predictors of Pancreatic Fistula and Pseudocyst following Laparoscopic Distal Pancreatectomy: A Retrospective Study

doi:10.21203/rs.3.rs-3105321/v1

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Preoperative Cross-Sectional Area and Thickness of Pancreatic Stump as Possible Predictors of Pancreatic Fistula and Pseudocyst following Laparoscopic Distal Pancreatectomy: A Retrospective Study

https://doi.org/10.21203/rs.3.rs-3105321/v1

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Purpose

This retrospective study investigates the association between the preoperative radiographic measurements of pancreatic thickness, cross-sectional area and the postoperative outcomes in laparoscopic distal pancreatectomy (DP) patients.

Methods

A total of 27 patients who underwent DP between May 2019 and February 2022 were included. Preoperative thoracoabdominal computed tomography (CT) measurements of pancreatic thickness and cross-sectional area were analyzed for their potential role in predicting postoperative pancreatic fistula (POPF) and pseudocyst formation.

Results

Our findings revealed a significant correlation between pancreatic thickness and amylase levels in the drain fluid on postoperative day one (POD1). Furthermore, pancreatic thickness emerged as a robust predictor for the formation of postoperative pancreatic pseudocysts. Notably, no significant association was observed between the cross-sectional area of the pancreas and either the drain amylase levels or pseudocyst formation.

Conclusions

These findings accentuate the potential role of preoperative CT evaluation, specifically the measurement of pancreatic thickness, in predicting the risk of POPF and pseudocyst formation after DP. It can contribute to tailored perioperative procedures and strategic patient management, ultimately enhancing patient outcomes. The present study underscores the importance of incorporating radiographic assessments into preoperative planning for patients undergoing DP.

distal pancreatectomy

pancreatic fistula

computed tomography

laparoscopy

thickness

Laparoscopic distal pancreatectomy (DP) has emerged as the preferred surgical approach owing to advancements in devices and techniques, offering patients earlier recovery and shorter hospital stays than conventional open DP [1]. However, postoperative pancreatic fistula (POPF) remains a significant challenge that contributes to postoperative morbidity and mortality. POPF can lead to devastating complications including pseudoaneurysm rupture, bleeding, intra-abdominal abscess, and sepsis [2].

Various studies have reported an incidence of POPF ranging from 18.6–64.9% following DP [3–5], underscoring the need for accurate risk prediction to guide appropriate patient management strategies. A review analysis of 2026 patients who underwent DP showed that POPF depends more on underlying patient factors (e.g., preoperative nutrition level, age, and obesity) than on surgical techniques (e.g., method of resection, biologic sealant, and prophylactic octreotide) [6]. These findings emphasize the importance of individualized risk assessment to optimize patient outcomes. However, the role of preoperative radiographic evaluation in predicting POPF remains debatable.

To address this knowledge gap, the primary objective of this study was to investigate the predictive value of preoperative radiographic findings for assessing the risk of POPF after laparoscopic DP. This study contributes to the development of personalized risk assessment models by elucidating the association between preoperative radiographic findings and POPF. Such models have the potential to guide surgical planning, optimize patient selection, and improve the overall postoperative outcomes in patients undergoing laparoscopic DP.

Study Design

This study utilized a retrospective design to investigate the association between preoperative radiographic measurements and the occurrence of postoperative pancreatic fistula (POPF) and pseudocysts following laparoscopic distal pancreatectomy (DP). Medical records of patients who underwent laparoscopic DP at Kashiwa Kousei General Hospital between May 2019 and February 2022 were retrospectively reviewed.

Data Collection

The data collection process involved extracting relevant information from electronic charts and reviewing case files. A total of 27 patients were included in the study cohort, and quality control measures were implemented to ensure data accuracy and prevent misclassification.

Operative Procedure

The operative procedures for laparoscopic DP varied according to the chronology of the cases. The initial 10 cases involved pancreatic transection using Echelon 60 mm Black or Green staplers. In contrast, the subsequent 17 patients underwent LCS (Harmonic™) for pancreatic transection. In these cases, the main pancreatic duct was identified, ligated with 4-0 Proline, and divided. The pancreatic stump was closed using the fish-mouth technique with 3-0 silk under a laparoscopic view instead of a stapler. The enrolled patients had tumors located in the body or tail of the pancreas and underwent distal pancreatectomy with D1 or D2 lymph node dissection. Closed drain tubes were placed on the pancreatic stump, and a fibrin sealant was applied around the pancreatic stump.

Measurements

All enrolled patients underwent thoracoabdominal computed tomography (CT) within 3 months before the surgery. CT examinations were performed using a 128-slice Siemens CT scanner (SOMATOM Definition Edge). Two board-certified hepato-pancreas-biliary surgeons and one board-certified radiologist independently reviewed the CT images. The reviewers were blinded to the patients’ outcomes and utilized axial images to obtain linear measurements of pancreatic thickness at the neck of the pancreas, specifically anterior to the superior mesenteric vein (SMV), which was anticipated to be divided. The measurements of thickness and cross-sectional area of the pancreas on the supra-mesenteric vein (SMV) were obtained using the SYNAPSE VINCENT software (Fuji Film Medical). Cross-sectional areas were calculated by drawing a circle on the pancreatic border utilizing sagittal images on the same planes where the thickness of the pancreas were measured.

Surveillance and Follow-up

Postoperative complications were tracked using abdominal CT scans performed six months after the surgery to identify any recurrences or pseudocysts.

Ethical approval

This study was conducted in accordance with the STROBE guidelines and the principles of the Declaration of Helsinki. The ethical review board of Kashiwa Kousei General Hospital approved the study protocol (#210010, 10^th/Nov/2021) and the patients’ data was registered on 15^th/Nov/2021. All patients provided informed consent for their data to be used for research purposes.

Statistical analysis

Linear regression analysis was employed to examine the association between the postoperative drain amylase level and the thickness or cross-sectional area of the neck of the pancreas. Logistic analysis was used to evaluate the relationship between postoperative drain amylase levels and postoperative pseudocyst formation. All statistical tests were two-tailed, with p-values less than 0.05 considered statistically significant. Statistical analyses were performed using R version 4.3.1. (R foundation, Vienna, Austria).

Patient Characteristics

A total of 27 patients, comprising 13 males and 14 females were included in this study. The median values of the body mass index (BMI), duration of hospital stay, and prognostic nutritional index (PNI) were 21.7 (range: 16.1 - 31.1), 13 days (range: 6–51 days), and 48.8 (range: 45.7 to 56.3), respectively. The median thickness and cross-sectional area of the pancreas were 11.5 mm (range: 6.74 - 20.01) and 360 mm² (range: 148 - 556), respectively (Table 1).

Method for the determination of Pancreatic Transection and Drain Amylase Levels

The method of pancreatic transection varied among patients, with Echelon Black utilized in 2 cases, Echelon Green utilized in 8 cases, and the fish-mouth closure technique utilized in 17 cases. The median drain amylase level on postoperative day 1 (POD1) 1 was 1,357 IU/L (range: 70 to 34,037 IU/L).

Pancreatic Thickness and Drain Amylase Levels

Figure 1 shows the association between pancreatic thickness and the logarithmically transformed amylase level in the drain fluid placed on the pancreatic stump on postoperative day 1. Linear regression analysis demonstrated a statistically significant correlation between these two variables (coefficient = 0.0957; 95% confidence interval [CI]: 0.00463–0.145; p = 0.0008). Furthermore, logistic regression analysis revealed that pancreatic thickness served as a significant clinical indicator of postoperative pancreatic pseudocysts (odds ratio [OR]: 0.233; 95% CI: 0.00445–0.462; p = 0.0457) (Figure 2).

Pancreatic Cross-Sectional Area and Drain Amylase Levels

Upon assessing the relationship between the logarithmically transformed drain amylase level and the cross-sectional area of the pancreas, linear regression analysis did not identify a significant association between these variables (coefficient: 0.191; 95% CI: -0.204 to 0.532; p = 0.34) (Figure 3). In addition, the cross-sectional area of the pancreas was not a significant clinical indicator of postoperative pancreatic pseudocysts (OR:0.002; 95% CI: -0.006 to 0.011) (Figure 4).

This retrospective study aimed to unravel the relationship between preoperative radiographic measurements of the pancreas and postoperative outcomes in patients who underwent laparoscopic distal pancreatectomy (DP). Our findings demonstrate a significant correlation between pancreatic thickness and amylase levels in the drain fluid, with the pancreatic thickness being a reliable indicator of postoperative pancreatic pseudocysts. However, no significant relationship was found between the cross-sectional area of the pancreas and either drain amylase levels or postoperative pseudocyst formation.

Limited data are available on the preoperative prediction of postoperative pancreatic fistula (POPF) after distal pancreatectomy (DP). However, objective information obtained through a preoperative radiological workup regarding the risk of POPF could assist surgeons in making informed decisions regarding tailored perioperative procedures, strategies, and pathways [7].

Previous studies have attempted to predict postoperative POPF using preoperative MRI to evaluate pancreatic fat [8, 9]; however, the link between fat accumulation and POPF is still uncertain [10-12]. The fact that MRI is performed in limited facilities and that evaluating fat preoperatively using MRI is not cost-effective might be responsible for this uncertainty. Regarding pancreaticoduodenectomy, the utilization of MRI in clinical practice is also constrained by its low frequency of use, with MRI assessments conducted in less than 10% of patients undergoing pancreaticoduodenectomy (PD) [13]. Therefore, we attempted to use the thickness and cross-sectional area of the pancreas, which could be easily obtained using preoperative CT.

Regarding DP, there have been few studies on the prediction of postoperative pancreatic fistulas using CT. These studies have suggested that the pancreatic thickness-to-main pancreatic duct diameter ratio [14] and the remnant volume of the pancreas [15] can be significant predictors of POPF. Our results align with those of previous studies that have suggested a correlation between pancreatic thickness and the risk of POPF after DP [16, 17] but conflicted with studies that predicted that cross-sectional area is also a significant predictor of POPF after DP [12]. As the pancreatic thickness and volume decrease, driven by the occurrence of parenchymal atrophy-associated pancreatic fibrosis, there is also a potential decrease in pancreatic enzyme production, as well as in the likelihood of developing a postoperative pancreatic fistula (POPF) and subsequent pseudocysts. We assume that, among patients with the same cross-sectional area of the pancreatic transection, a thick, round-shaped pancreas has a higher risk of POPF and subsequent pseudocyst formation than a thin, flat-shaped pancreas. In other words, we hypothesize that a flat-shaped pancreas is more likely to have parenchymal atrophy than a round-shaped pancreas, making the cross-sectional area an insignificant predictor of POPF and subsequent pseudocyst.

The observed correlation between pancreatic thickness and amylase levels in the drain fluid suggests that a thicker pancreas may be associated with a higher risk of POPF and pseudocysts. This finding has potential clinical implications as it may aid surgeons in identifying patients who are at an increased risk of developing this complication. By identifying high-risk individuals preoperatively, appropriate preventive measures can be implemented to minimize the incidence and severity of POPF. Further research is warranted to validate these findings and develop risk stratification models that incorporate radiographic evaluations and other clinical parameters.

This study has a few limitations of its own. First, the retrospective design may have introduced a selection bias and potential confounding factors. Second, the sample size was relatively small, which may limit the generalizability of our findings. Additionally, the analysis focused on a single institution, which may have limited the external validity of the results. Finally, this study did not explore other potential risk factors for POPF, such as patient comorbidities or operative techniques, which may have influenced the outcomes.

Our study provides evidence that supports the role of preoperative radiographic evaluation, specifically pancreatic thickness, as a potential predictor of POPF after laparoscopic DP. These findings underscore the importance of incorporating radiographic assessment into preoperative planning to identify patients at higher risk of developing POPF and pseudocysts. Further prospective studies with larger sample sizes are needed to validate these findings and explore the clinical utility of radiographic evaluation in guiding surgical decision-making and optimizing patient outcomes.

Conflict of Interest: The authors declare that they have no conflicts of interest to declare.

Funding: None.

Presentation: The 34^th Meeting of the Japanese Society of Hepato-Biliary-Pancreatic Surgery, Takamatsu, Ehime, Japan.

Approved by Institutional Review Board (IRB): Anonymized or unidentifiable data were used and the study was approved by the Review Board of Kashiwa Kousei General Hospital. (#210010, on 10^th/Nov/2021).

Acknowledgments

I would like to extend my sincere thanks to Dr. Fumiya Omata for his invaluable feedback about statistical analysis.

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Table 1. Clinical characteristics of the patients enrolled in this study.

	Median (Range)
Age	64 (18 - 82)
Gender
Male	13
Female	14
Thickness of the pancreas	11.5 mm (6.74 – 20.01)
Cross-sectional area of the pancreas	360 mm² (148 - 556)
Transection
Echelon Black 60 mm	2
Echelon Green 60 mm	8
Fish-mouth technique	17
Duration of hospital stay	13 days (6-51)
Body Mass Index (BMI)	21.7 kg/m² (16.1 – 31.1)
Spleen preserved	6
Prognostic Nutritional Index (PNI)	48.8 (45.7 – 56.3)

No competing interests reported.

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Preoperative Cross-Sectional Area and Thickness of Pancreatic Stump as Possible Predictors of Pancreatic Fistula and Pseudocyst following Laparoscopic Distal Pancreatectomy: A Retrospective Study

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