Routine surveillance endoscopy via the ileostomy, with random biopsies, is performed twice a week for the first month after transplant. This procedure enables the diagnosis of rejection prior to the manifestation of clinical signs and symptoms. For the subsequent 1–2 months, endoscopy and biopsies are performed every week. Indications for biopsies include unexplained fever, change in stoma output or appearance, gastrointestinal bleeding, and skin rash. Gross appearance of the mucosa does not correlate with the histologic findings, but endoscopy with biopsy remains the gold standard for diagnosis of rejection in the intestinal allograft. The diagnosis of rejection is based on pathologic criteria: apoptosis, cryptitis, and exfoliation. Unfortunately, these findings can also be present in infectious enteritis [16, 17].

Stomal output increases rapidly after the first few hours and may reach several liters a day. Bicarbonate losses may be marked and need to be replaced if this causes metabolic acidosis. Diarrhea is common after SBT and is often multifactorial in origin. Denervation of the grafted small bowel is probably the major cause of diarrhea, but other causes include ischemia–reperfusion injury, rejection, graft-versus-host disease, and CMV enteritis. Fecal calprotectin assays might help in the early diagnosis of rejection and can be used on an outpatient basis, particularly in those patients who have had their ileostomy closed, although the utility of this assay is restricted by significant interpatient variability [18, 19]. The role of citrulline as a quantitative marker of rejection is being investigated. Citrulline, a nonessential amino acid, is produced by the intestinal mucosa and is present in the serum. Citrulline levels reflect the functional absorptive capacity of the intestine. In patients with short gut syndrome, the postabsorptive plasma concentration of citrulline is not only a measure of functional absorptive bowel length but is also an indicator of permanent intestinal failure. In transplanted patients, plasmatic levels of citrulline decreased during rejection and returned to prerejection levels upon successful treatment of rejection, and the severity of rejection inversely correlated with citrulline levels.

The postoperative care of intestinal transplanted patients is complicated by their markedly debilitated state, balanced immunosuppressive regimens to prevent rejection, and the necessity to prevent and treat infection. The primary treatment goal is to maximize benefits while minimizing the morbidity of immunosuppressive agents. A natural consequence of transplantation of an organ exposed to external microorganisms in the presence of profound immunosuppression is the susceptibility of the recipient to local and systemic infections. Gastrointestinal decontamination is required in small bowel transplantation and puts the patient at a very high risk of CMV new infection or reactivation. Every patient is therefore treated (except when donor and recipient are both CMV negative), according to this protocol: D+/R− requires ganciclovir plus specific anti-CMV Ig, and D+/R+ or D−/R+ needs to be treated with ganciclovir 5 mg/kg i.v. two times a day until the patient can receive 1 g × 3 per os up to 3–4 months postoperatively. A major advance in the reduction of graft failure and patient mortality has been introduced by improved diagnosis, prophylaxis, and therapy of viral infections and their complications. Routine use of polymerase chain reaction (PCR) assay for early viral detection has greatly reduced the adverse influence of this virus. Monitoring Epstein–Barr virus (EBV) by PCR, which might be a prelude posttransplant lymphoproliferative disease (PTLD) [20], enables the reduction of immunosuppression or, in advanced cases, the use of the anti-CD20 monoclonal antibody, rituximab. The presence of rising EBV titers on routine surveillance often provides a trigger to reduce the dose of maintenance immunosuppression by 25–50 %. PTLD which is refractory to these measures, recurrent or progressive, often requires chemotherapy as for non-Hodgkin’s lymphoma [16].

Fluid management is the major postoperative problem after small bowel and multiple organ transplantation because the fluid and electrolyte needs of the transplant recipient are highly variable. Fluid replacement is usually guided by the blood pressure, right atrial pressure, pulmonary capillary wedge pressure, and urine output, but a reliable monitoring technique to determine volemia is needed. In the immediate posttransplant period, the graft is subject to mucosal sloughing secondary to ischemia–reperfusion injury, and the patient can lose large amounts of fluid through the graft. Preservation injury is however a relatively minor problem in intestinal transplantation because of the intestine’s great capacity for epithelial regeneration. In addition, associated bicarbonate loss can be high. During episodes of rejection, the patient can also have exaggerated fluid losses that can lead to dehydration. Third-space fluid requirements can be massive, and inadequate replacement leads to end-organ dysfunction, particularly renal failure. Central venous pressure monitoring, preferably with pulmonary arterial catheterization, is essential as any other monitoring technique which can often be a reliable picture of body volume distribution. Several liters of fluid may be required in the initial 24–48 h postoperatively simply to maintain central pressures adequate to provide a satisfactory urine output. During this time, the patients may develop extensive peripheral edema, which dissipates over the next few days as the fluids are mobilized and requirements stabilize. This phenomenon occurs after all abdominal surgery, but these patients have significantly greater fluid shifts than do patients undergoing major non-transplantation abdominal surgery. However, continued increases in fluid requirements may herald infection or rejection. The aim is to commence enteral feeding as early as possible after transplantation. Ileus usually persists for the first few postoperative days as ischemia–reperfusion injury resolves [21]. Most centers introduce enteral intake between 3 and 7 days postoperatively, with some waiting until stomal output is demonstrated. Typically, a small volume (10 mL/h) of non-elemental feeds is started initially; the aim is to provide all nutritional requirements enterally, with complete withdrawal of parenteral nutrition within 4–6 weeks. This early transition enhances graft adaptation and minimizes postoperative complications. Initially, feeding is given via an enteral tube. Because gastric emptying is delayed early after transplantation, jejunal feeding is the preferred route, most commonly via a jejunostomy, fashioned at the time of the transplant. Some units use nasojejunal tubes [16]. Transition to oral diet is individualized as tolerated and tends to occur more rapidly in adults than children. Up to 45 % of children have continued to require nasogastric tube feeding at 2 years; factors such as food aversion, high relative fluid and energy requirements, and prior adverse dietary experiences with a tendency to anorexia often contribute to delayed transition. Enteric lymphatics are often disrupted during surgery, with recovery often taking weeks to months. Chylous ascites might develop and require repeated paracentesis over a period of weeks.