Geometric simplification by ductal unification of dual pancreatic ducts during pancreaticojejunostomy

Abstract

Background

Anatomical variations of the pancreatic duct are common; however, two closely approximated ductal lumens at the margin of pancreatic transection present a distinct reconstructive challenge during pancreaticoduodenectomy (PD). When the inter-ductal distance is minimal, conventional assumptions underlying pancreaticojejunostomy may not apply.

Case presentation

In this two-case report, two patients undergoing PD were preoperatively diagnosed with dual pancreatic ducts by contrast-enhanced computed tomography and magnetic resonance cholangiopancreatography. Histopathological assessment demonstrated minimal inter-ductal distances (3.05 mm and 0.35 mm) at the transection margin in each patient.

Separate duct-to-mucosa anastomoses were considered technically unfavorable because the pancreatic parenchymal cuffs were too small to allow secure suturing and because of the risk of ischemia in the narrow intervening pancreatic bridge. Therefore, a ductal unification strategy was adopted. The septum between the ducts was sealed using an ultrasonic device, divided under hemostatic control, and sutured to create a single ductal orifice. Standard duct-to-mucosa pancreaticojejunostomy was then performed within the Blumgart framework. Both patients had uneventful postoperative courses without clinically relevant postoperative pancreatic fistulae.

Conclusion

Ductal unification may represent a feasible technical option in carefully selected cases of closely approximated dual pancreatic ducts, but further experience is required before any recommendation can be made.

Supplementary Information

The online version contains supplementary material available at https://doi.org/10.1186/s12893-026-04030-8.

Introduction

Anatomical variations of the pancreatic duct are frequently encountered in radiological and anatomical studies. Magnetic resonance cholangiopancreatography (MRCP)-based analyses have demonstrated that ductal variations, including pancreas divisum and other branching patterns, are not uncommon in the general population [1–3]. Thus, pancreatic ductal diversity represents a spectrum of normal anatomical variation rather than a rare anomaly.

In contrast, the reconstructive implications of these variations during pancreaticoduodenectomy (PD) have received limited attention. Postoperative pancreatic fistula (POPF) remains one of the most significant complications following PD, and a soft pancreatic parenchyma and reduced ductal diameter are well-established risk factors [4, 5]. Although duct-to-mucosa and invagination pancreaticojejunostomy are widely performed, meta-analyses have not confirmed that one technique is significantly superior to the other [6]. These conventional techniques implicitly assume the presence of a single main pancreatic duct at the transection margin. When two ductal lumens are identified in close proximity, however, standard reconstructive assumptions based on a single-duct anatomy may no longer apply.

We hypothesized that ductal unification could restore geometric simplicity by converting two closely approximated ductal lumens into a single reconstructable ductal orifice, thereby reducing suture crowding and facilitating duct-to-mucosa pancreaticojejunostomy in such situations. Here, we report two patients with closely approximated dual pancreatic ducts that were identified at the transection margin during PD, and describe a hemostatically controlled unification strategy integrated within the Blumgart framework [7, 8].

Case presentation

Two consecutive patients undergoing PD were found intraoperatively to have dual pancreatic ducts at the transection margin with minimal inter-ductal distances (Fig. 1).

Fig. 1.

Preoperative imaging of two closely approximated ductal lumens in Cases 1 and 2. A MRCP in Case 1 demonstrates two closely approximated pancreatic ducts, indicated by red and pink arrowheads. B Contrast-enhanced CT in Case 1 demonstrates the anatomy of the pancreatic duct at the transection level, with the two ducts indicated by blue and light blue arrowheads. C ERCP in Case 1 delineates duplication of the pancreatic duct, with the two ducts indicated by orange and yellow arrowheads. D MRCP in Case 2 demonstrates dual pancreatic ducts, indicated by red and pink arrowheads. E Contrast-enhanced CT in Case 2 demonstrates the anatomy of the pancreatic duct at the transection level and markedly attenuated pancreatic parenchyma, with the two ducts indicated by blue and light blue arrowheads

Both patients had been preoperatively diagnosed with dual pancreatic ducts by contrast-enhanced computed tomography and MRCP. In Case 1, duplication was confirmed by endoscopic retrograde cholangiopancreatography (ERCP). In Case 2, cannulation of the main pancreatic duct during ERCP was unsuccessful, and duplication could not be demonstrated endoscopically despite being identified during preoperative imaging.

The term “dual pancreatic ducts” is used descriptively in the present report to indicate the presence of two closely approximated ductal lumens at the transection margin. Although Case 1 showed ductal duplication on ERCP in addition to CT and MRCP, ERCP confirmation was not possible in Case 2 despite suggestive findings on CT and MRCP. Therefore, the precise anatomical classification of this ductal configuration remains uncertain, and the operative focus of the present report was the technical problem created by two closely approximated ductal lumens at the transection margin.

In Case 1, the lesion was located in the pancreatic body, and the final pathological diagnosis was intraductal papillary mucinous carcinoma (IPMC), TS2, pTis, N0, pStage 0, with R0 resection. The total operative time was 667 min, the blood loss was 100 g, and the pancreaticojejunostomy construction time was 52 min. Pancreatic transection was performed at the pancreatic body. The pancreatic parenchyma was of normal consistency, and three transpancreatic mattress sutures were applied within the Blumgart framework following ductal unification. In Case 2, the lesion was located in the pancreatic body in the setting of a pancreatic head pseudocyst, and the final pathological diagnosis was serous cystadenoma. The total operative time was 954 min, the blood loss was 300 g, and the pancreaticojejunostomy construction time was 34 min. Pancreatic transection was performed at the pancreatic body. The pancreatic parenchyma was markedly attenuated. After ductal unification, a duct-spanning mattress suture was placed, followed by additional cranial and caudal seromuscular reinforcing sutures.

The detailed perioperative findings are summarized in Table 1.

Table 1.

Detailed perioperative findings of Cases 1 and 2

In both cases, the septum between the ducts was sealed by an ultrasonic device prior to division to ensure hemostatic control, and then sutured to create a single ductal orifice (Fig. 2).

Fig. 2.

Stepwise schematic illustration of ductal unification and subsequent pancreaticojejunostomy. A Ultrasonic sealing of the septum between the two closely approximated ducts at the transection margin. B Sealing of the septum to secure hemostatic control before division. C Initial suturing after division of the septum to create a single ductal orifice. D Completion of division of the septum and ductal unification. E Alignment of the unified duct with the jejunal opening for duct-to-mucosa pancreaticojejunostomy. F Completed pancreaticojejunostomy within the Blumgart framework

Histopathological examination of hematoxylin and eosin-stained sections from the resected pancreatic transection margin demonstrated an inter-ductal distance of 3.05 mm in Case 1 and 0.35 mm in Case 2 (Fig. 3).

Fig. 3.

Macroscopic and histopathological assessments of inter-ductal distances and duct sizes in Cases 1 and 2. Macroscopic photographs of the pancreatic transection margins (left) and corresponding hematoxylin and eosin-stained sections (right) in both cases. In Case 1, two distinct ductal orifices are visible macroscopically. In Case 2, the ducts are very closely approximated and less clearly distinguishable on the macroscopic specimen. Histopathological measurements confirmed an inter-ductal distance of 3.05 mm in Case 1 and 0.35 mm in Case 2. For each duct, the longest diameter and the perpendicular diameter were measured. The larger duct is indicated by a red arrow and the smaller duct by a blue arrow

Postoperative pancreatic fistula was assessed according to the 2016 International Study Group of Pancreatic Surgery (ISGPS) definition. In our institution, the reference range for serum amylase was 44–132 U/L; therefore, the biochemical leak threshold was 396 U/L. In Case 1, the posterior drain amylase level on postoperative day (POD) 3 was 470 U/L, which met the biochemical leak criterion. However, no clinically relevant postoperative pancreatic fistula developed. The amylase levels in the anterior and posterior pancreaticojejunostomy (PJ) drains subsequently decreased to 26 U/L and 33 U/L on POD4, and the anterior PJ drain amylase level further decreased to 27 U/L on POD5; no fluid collection or other related complications were observed. In Case 2, the drain amylase levels remained below the biochemical leak threshold throughout the postoperative course (the anterior/posterior PJ drains and the behind-hepaticojejunostomy [HJ] drain: 35/33/38 U/L on POD1, 17/17/18 U/L on POD3, and 13/15/13 U/L on POD4; the anterior PJ drain 8 U/L on POD5), and the case did not meet the biochemical leak criterion. The behind-HJ drain was removed on POD3 in Case 1, the posterior PJ drain on POD4, and the anterior PJ drain on POD5; in Case 2, the posterior PJ drain and behind-HJ drain were removed on POD4, and the anterior PJ drain on POD5. No somatostatin analogues were used in either case. No postoperative complications occurred according to the Clavien–Dindo classification, and no readmission was required. Postoperative imaging performed approximately 1 week after surgery showed no fluid collection in either case. The follow-up duration was 6 months in Case 1 and 3 months in Case 2. Detailed operative anatomy, pancreatic transection lines, and representative intraoperative findings are shown in Additional files 1 and 2.

Discussion

Although anatomical variations of the pancreatic duct are common, the reconstructive dilemma created by two closely approximated ductal lumens at the pancreatic transection margin has not been well characterized. The key difficulty is not ductal duplication itself, but the spatial constraint that limits the placement of sutures, available tissue support, and local perfusion.

The critical configuration is not the mere presence of dual pancreatic ducts, but two closely approximated ducts separated by only a few millimeters, leaving an insufficient pancreatic parenchymal cuff for secure independent suturing. Accordingly, the term “dual pancreatic ducts” is used in this report as a pragmatic descriptive term based on the operative configuration at the transection margin rather than as a definitive anatomical classification. In this setting, separate duct-to-mucosa anastomoses may result in suture crowding, increased needle trauma, and compromise of the narrow intervening pancreatic bridge. A ductal bite of approximately 2 mm may be necessary for the secure suturing of each duct, although this measurement should be regarded as a technical assumption rather than a universally validated cutoff value. Additionally, a diameter of 3 mm or less for the main pancreatic duct has been associated with increased technical difficulties and increased risk of postoperative pancreatic fistula [9–13]. Accordingly, the inter-ductal distance should be regarded as the primary determinant of the surgical strategy, whereas ductal size should be considered an important modifying factor.

In one of our prior surgical cases, separate duct-to-mucosa anastomoses were performed for dual pancreatic ducts measuring 1 and 3 mm in diameter and separated by 3 mm; the drain amylase level on postoperative day 3 was 740 U/L, fulfilling the biochemical definition of postoperative pancreatic fistula despite an otherwise uneventful course. This experience anecdotally suggests the technical difficulty of separate suturing when the inter-ductal distance is less than 4 mm, particularly when one duct is extremely narrow.

In our two current cases, histopathological examination of hematoxylin and eosin-stained sections from the resected pancreatic transection margin specimen demonstrated inter-ductal distances of 3.05 mm and 0.35 mm, confirming that spatial constraint was the principal reconstructive problem. A simple geometric model further supports this concept. This model is intended as a conceptual aid to explain spatial constraint rather than as a clinically validated geometric threshold for operative decision-making. Assuming a 2-mm ductal bite (AB) defined perpendicular to the duct wall and a 13-mm 1/2-circle needle following its natural curvature through the pancreatic parenchyma, the required pancreatic parenchymal travel (AC) is approximately 3.55 mm on each side, corresponding to a theoretical inter-ductal distance of approximately 7.10 mm for two fully independent sutures. In patients with a hard pancreas, however, this requirement may be reduced because firmer parenchyma may allow a shallower or non-perpendicular needle trajectory while still providing adequate tissue support (Fig. 4). Therefore, an inter-ductal distance of approximately 4 to 7 mm may be regarded as a practical gray zone in which the choice between ductal unification and separate suturing depends on pancreatic texture, duct size, and operative feasibility, particularly because soft pancreatic tissue itself is a recognized risk factor for postoperative pancreatic fistula [11, 12].

Fig. 4.

Geometric model supporting the theoretical inter-ductal distance required for independent suturing. A, B In soft pancreatic tissue, the ductal bite (AB) is modeled as perpendicular to the duct wall, while a 13-mm 1/2-circle needle is assumed to follow its natural curvature through the pancreatic parenchyma. Under this condition, the required pancreatic parenchymal travel (AC) is determined by the needle radius (r), needle arc length (l), and ductal bite (X). When X = 2 mm and l = 13 mm, AC is approximately 3.55 mm on each side, corresponding to a theoretical inter-ductal distance of approximately 7.10 mm for two fully independent sutures. C, D In hard pancreatic tissue, this requirement may be reduced because firmer parenchyma may permit a shallower or non-perpendicular needle trajectory while still providing adequate tissue support

Based on our findings, we suggest a set of practical considerations for reconstruction in closely approximated dual pancreatic ducts. Very short inter-ductal distance may favor ductal unification, whereas a wider distance may permit separate duct-to-mucosa anastomoses. In intermediate situations, pancreatic texture, duct size, and the technical feasibility of separate suturing should all be considered (Fig. 5). The proposed distance ranges should not be interpreted as strict operative thresholds, but rather as approximate conceptual reference points. In particular, the approximately 7-mm range corresponds to the theoretical distance required for two fully independent sutures in the geometric model, whereas the shorter range reflects situations in which spatial constraint is likely to limit separate suturing.

Fig. 5.

Proposed conceptual framework for reconstruction of dual pancreatic ducts at the transection margin. When the inter-ductal distance appears to be very short, ductal unification may be considered because separate duct-to-mucosa anastomoses can be limited by an insufficient parenchymal cuff, suture crowding, ischemic risk to the intervening pancreatic bridge, and overlap of transpancreatic mattress sutures. When the inter-ductal distance appears intermediate, ductal size and the feasibility of separate suturing should be assessed. When the distance appears sufficiently wide, separate duct-to-mucosa pancreaticojejunostomies may be feasible. These considerations should be interpreted as a proposed conceptual framework derived from limited clinical experience and geometric reasoning rather than as a validated decision-making tool or strict intraoperative algorithm. The distance ranges shown in this framework are intended only as approximate conceptual reference points and should not be interpreted as operative thresholds

Previous reports of duplicated or bifid pancreatic ducts have described one-unit or duplicative reconstructive strategies, including double duct-to-mucosa anastomosis and the “two-in-one” method [14, 15]. However, the present report addresses a different technical problem. In double duct-to-mucosa reconstruction, the two native ducts are anastomosed separately to the jejunum. In the previously reported two-in-one method, two native ducts were anastomosed side by side to a single jejunal opening without creation of a new single ductal orifice. In contrast, our approach involved septal division and ductal remodeling to create a single reconstructable ductal orifice before duct-to-mucosa pancreaticojejunostomy. Thus, the technical essence of our approach is not simply one-unit reconstruction, but conversion of two closely approximated ducts into a single reconstructed ductal orifice when separate suturing is limited by spatial constraint. Our approach should therefore be interpreted as a configuration-specific practical refinement for spatially constrained dual ducts, rather than as a wholly new conceptual alternative to previously reported one-unit or duplicative reconstructions.

Ultrasonic sealing before septal division provides hemostatic control and facilitates remodeling into a circular unified lumen suitable for standard duct-to-mucosa alignment. Ultrasonically activated devices have been reported to be effective for vessel sealing and pancreatic tissue division [16–18]. This strategy allows reconstruction to be performed within the Blumgart framework, which has been reported to be safe and widely used [7, 8, 13, 19].

Another clinically relevant aspect is preoperative recognition. Although both patients were diagnosed by CT and MRCP, endoscopic confirmation was not feasible for one of our patients. This underscores the need for surgeons to anticipate unexpected ductal configurations and to prepare alternative reconstructive strategies.

Both patients had uneventful postoperative courses without clinically relevant postoperative pancreatic fistula. While our experience suggests that ductal unification may be technically feasible in selected patients with closely approximated dual pancreatic ducts, this report is limited to only two cases and does not allow any conclusion regarding superiority, safety, or reproducibility over separate duct-to-mucosa anastomoses. Accordingly, the present report should be interpreted as a technical description with conceptual implications rather than as evidence supporting a generally applicable reconstructive recommendation. Avoidance of clinically relevant postoperative pancreatic fistulas should be considered the most relevant clinical benchmark in this setting [5, 20].

Conclusions

Ductal unification may represent a feasible technical option in carefully selected cases of closely approximated dual pancreatic ducts, but further experience is required before any recommendation can be made.

Abbreviations

PD

Pancreaticoduodenectomy

POPF

Postoperative pancreatic fistula

MRCP

Magnetic resonance cholangiopancreatography

CT

Computed tomography

ERCP

Endoscopic retrograde cholangiopancreatography

Authors’ contributions

SH and YM conceived the report, performed the surgeries, collected the clinical data, and drafted the manuscript. MK performed the histopathological evaluation and contributed to interpretation of the pathological findings. NJ and KH contributed to the preoperative endoscopic and imaging assessment. NO contributed to the investigation and clinical review of the prior case. NS, HSh, AO, SY, RN, KW, YY, KSa, TSh, KShi, HSa, TT, and ST contributed to perioperative patient management, multidisciplinary case discussion, interpretation of the clinical, radiological, and operative findings, and critical revision of the manuscript for important intellectual content. All authors read and approved the final manuscript.

Funding

No specific funding was received for this study.

Data availability

No datasets were generated or analysed during the current study.

Declarations

Ethics approval and consent to participate

This study was conducted in accordance with the Declaration of Helsinki. Institutional review board approval was obtained from Nagoya City University East Medical Center. Written informed consent for participation was obtained from both patients.

Consent for publication

Written informed consent was obtained from both patients for publication of this case report and any accompanying images.

Competing interests

The authors declare no competing interests.