Type 3 and type 4 of reconstruction imply a segmental resection, resulting in a longer defect of the venous axis. For all attempts of these resections, the mesenteric root should be mobilized completely by resolving the attachment of the right hemicolon to the retroperitoneal adhesions (Cattell-Braasch manoeuver [20]). This allows to bridge even long distances after resection of the vein and graft interposition (type 4) can often be avoided.

In type 3 resections, SMV/PV continuity is restored by a direct end-to-end anastomosis (Fig. 8.3). In case of corresponding diameters of the distal and proximal lumen, there is no obstacle for free venous drainage of the bowel. If it is not possible to bridge the resected length by approximation of the proximal and distal vessel lumen and performing a direct anastomosis, a vascular graft needs to be inserted. For this type 4 reconstruction, autologous as well as allogenous grafts can be used. Regarding autologous grafts, there are various possibilities (Table 8.1). Most commonly, the saphenous vein, the left renal vein (in case of patency of the ipsilateral ovarian/testicular vein to preserve kidney drainage), or the internal jugular vein have been described (Table 8.1, [21–33]). All of these grafts imply that a harvesting procedure must be performed and that the respective vessel is available and suitable with respect to the diameter and to the length which is needed for the reconstruction. As described before, also a peritoneal patch may be harvested and used to create a tubular graft (i.e., by placing the patch around a drainage tube and form the graft by longitudinal suture [19]). All of the described techniques of autologous graft insertion have been reported with good outcomes regarding postoperative morbidity and patency [21–34]. If no autologous graft material is available or in case of unplanned venous resection, that requires an “emergency” reconstruction, synthetic material represents a valid option for reconstruction, as well [28, 30]. A ringed polytetrafluoroethylene (PTFE) graft seems preferable as this type of prosthesis offers excellent flow conditions and patency rates [30, 34, 35]. The disadvantage of inserting a synthetic graft lies in the fact that any artificial material may cause problems in case of infection or anastomotic leakage. The in situ situation of a graft in combination with a pancreatic fistula must be regarded as a high-risk constellation for arrosional bleeding or for long-lasting graft infection, which is known difficult to treat. However, in recent clinical studies, no difference in surgical outcome and long-term survival was shown when different types of venous reconstruction (venorrhaphy, end-to-end anastomosis, graft insertion) were compared [30].

An unsolved problem is the confirmation of a R0 situation during PV/SMV resection. As the small bowel does not tolerate warm ischemia due to complete venous congestion (regardless of a synchronous clamping of the SMA) for a long time, the performance of a frozen section of the distal and proximal cut margin of the resected vein segment cannot be routinely performed. From large series, the R1 rate in this position ranges from 13% up to 50% [25, 26, 30]. Despite these considerably high rates in some studies, the oncological outcome may not be compromised and seems to be mostly determined by other factors (i.e., lymphatic spread, lymph node metastases, R1 status in other positions [16]).

Management of the splenic vein is another important issue in segmental resections of the SMV/PV [36]. If the site of resection is located clearly above or below the splenic vein confluence, this can be preserved without any changes in the physiological venous drainage of spleen and stomach. However, as the venous confluence is often the site of tumor infiltration, the proximal splenic vein is often part of the resected specimen. From the technical point of view, the splenic vein can be closed or reinserted during venous resection in PD. In case of lateral reinsertion of the splenic vein, it must be assured that no tangential tension on the venous anastomoses occurs (Fig. 8.4). This may otherwise promote narrowing and thrombosis of the respective vessels. Therefore, a closure of the splenic vein without reinsertion can be advisable in certain situations as long as this does not compromise splenic and gastric drainage which is sustained via left-sided collaterals in many patients.

Another aspect that has to be taken into account during venous resections is the perfusion of the right hemicolon. In case of removal of the middle colic vein or the ileocolic vein, which are common locations for lymph node metastases in PDAC [37], a right colectomy may be necessary to avoid colon-associated ischemic complications.

In distal pancreatectomy (DP), venous resections are less frequently performed. The technical challenge during this procedure is the fact that the remaining pancreatic head may block the approximation of the proximal and distal lumen and consequently create tension of both ends when a direct suture is attempted. Furthermore, a lateral compression of the anastomosis with a consequent thrombosis may occur. To avoid both of these situations, a segmental graft insertion is advisable to achieve best rates of patency. Due to the high risk of postoperative pancreatic fistula in DP, autologous graft material should be chosen and a synthetic graft with the inherent risk of fistula-associated infection should be avoided.

Regarding total PD with venous resections, an end-to-end anastomosis with or without graft insertion is possible and the splenic vein is generally removed as most total PDs for oncological indications include splenectomy. In this situation, the venous drainage of the stomach needs to be considered, i.e., by preserving the gastric coronary vein (see Sect. 8.4). Otherwise, an adopted resection of the stomach must be performed to avoid ischemic complications.