In this model, the recipient’s own small bowel is left in the abdomen and the graft is not connected into the intestinal tract of recipient. The graft venous outflow is reestablished using the vena cava caudalis (Fig. 13.1). The main advantage of this model is relatively easy technical implementation contrary to other models and the possibility to easily perform enteral biopsy of the graft. Even if the heterotopic model of SBT does not imitate the physiological conditions as well as orthotopic transplantation , it is suitable for immunological study and the study of ischemic reperfusion injury.

Unlike heterotopic transplantation , in this model the small bowel of the recipient is removed and replaced with a donor’s graft. Venous drainage is re-established with porto-caval anastomosis. Compared to heterotopic transplantation, this model is associated with increased mortality though a skilled surgeon could achieve more than 85 % of animal survival [9] (Fig. 13.2). The main advantage of this model is that the entire graft is exposed to normal intraluminal environment of recipient, which consists of nutrition, gastrointestinal juice and germs and thriving of recipient absolutely depends on functional integrity of the bowel graft. Orthotopic SBT is suitable for physiological research of the transplanted graft, e.g. functional tests, growth of the animal and metabolic changes.

This technique is similar to the above described technique with the difference being the venous anastomosis performed as a porto-portal connection (Fig. 13.3). Ischemia time during the clamping of venous anastomosis is an important factor for success of the procedure. If the time is longer than 15 min venostasis results in increased mortality. Even if this model represents the physiological way of venous drainage, in some studies the superiority over the systemic venous drainage was not proven [10, 11]. This model is always intended for special research such as pharmacokinetics of drugs metabolized after bowel resorption in the liver [2].

The standard surgical technique of small bowel transplantation using a “handmade” vascular anastomosis is a technically demanding microsurgical procedure requiring an experienced surgeon with long-time training. For this reason, SBT is always frustrating for the beginner associated with high mortality of experimental animals. The cuff technique is a simple method of microvascular anastomosis where the vascular connection of the polyethylene cuffs are inserted to the donor and recipient vessel and are then connected together (Fig. 13.4). The main advantage of this technique is the easy and fast performance of an unexperienced surgeon. There are exist some different types of this technique where the cuff is used for both anastomoses (arterial and venous) or only for venous anastomosis [3, 12]. The cuff technique is described in detail in Chap. 6.​1.​5 Vascular Anastomosis with Using “Cuff Technique”.

This part of small bowel transplantation is described in Chap. 14.