**2. Indications**

IF is characterized by the inability to maintain protein energy, fluid, electrolyte or micronutrient balance due to gastrointestinal disease. If the patient does not receive parenteral nutrition or become a recipient of an intestinal transplant, IF ultimately leads to malnutrition and even death.

The leading causes of IF differ between pediatric and adult populations (**Table 1**).

TPN is the current standard of care for patients with IF. Nevertheless, as survival following ITx improves, it is anticipated that ITx will become a valid alternative to total parental nutrition. However, because of significant complications that can arise from surgery and long-term use of immunosuppressive therapy, strict eligibility criteria exist to ensure appropriate patient selection.


**Table 1.** Leading causes for intestinal transplantation in paediatric and adult populations.

Short bowel syndrome caused by surgical removal is the leading cause of IF (68%). As an early alternative to transplantation or total parenteral nutrition (TPN) for patients with short bowel syndrome, surgical bowel lengthening without transplant may be attempted. This requires the serial transverse enteroplasty (STEP) or longitudinal intestinal lengthening and tailoring (LILT) procedures. STEP and LILT are particularly successful in patients with decreased transit times and dilated bowel. These procedures lengthen the small bowel while keeping the total surface area the same. Bowel is either split lengthwise or cut obliquely at multiple points. This will lengthen the bowel and shrink the luminal diameter [12]. If successful, this may reduce the amount of TPN required, or negate its use altogether. If patients are not acceptable candidates for STEP or LILT, sometimes a reversal of small bowel direction may effectively increase transit times. If none of these operations are successful, the standard of care is TPN.

variety of organ transplantation compared with cyclosporine set the momentum for ITx as a

Over the past 30 years, there has been a gradual increase in ITx cases, with nearly 2900 ITx cases performed worldwide, although there has been a decline in recent years [7]. This change could be attributed to the formation of specialized IF units to prevent and manage intestinal failure-associated liver disease (IFALD) [8]. Other possible factors include: inadequate reimbursement rates below the cost of performing the transplant; the extensive infrastructure demands required to address the frequent social problems of IF patients; concern over the narrow risk-benefit ratio for ITx in an era of improving outcomes with long-term total parenteral nutrition (TPN) for selected diseases [9] and/or the limited availability of experienced personnel to fill key positions. Finally, some transplant centers may be more willing to judiciously offer isolated liver transplants to patients with the short bowel syndrome and IFALD

IF is characterized by the inability to maintain protein energy, fluid, electrolyte or micronutrient balance due to gastrointestinal disease. If the patient does not receive parenteral nutrition or become a recipient of an intestinal transplant, IF ultimately leads to malnutrition and even death.

TPN is the current standard of care for patients with IF. Nevertheless, as survival following ITx improves, it is anticipated that ITx will become a valid alternative to total parental nutrition. However, because of significant complications that can arise from surgery and long-term use of immunosuppressive therapy, strict eligibility criteria exist to ensure appropriate patient

The leading causes of IF differ between pediatric and adult populations (**Table 1**).

Gastroschisis Superior mesenteric artery thrombosis Crohn's disease Superior mesenteric vein thrombosis

Massive resection secondary to tumour Massive resection secondary to tumour

**Table 1.** Leading causes for intestinal transplantation in paediatric and adult populations.

life-changing therapy for patients with irreversible intestinal failure (IF) [5, 6].

290 Organ Donation and Transplantation - Current Status and Future Challenges

who have the potential for further intestinal adaptation [10, 11].

**Paediatric Adult**

Microvillus involution disease Trauma

Midgut volvulus Volvulus

Intestinal atresia Crohn's disease

Necrotizing enterocolitis Desmoid tumour

Chronic intestinal pseudo-obstruction Pseudo-obstruction

Hirschsprung disease Radiation enteritis

**2. Indications**

selection.

Currently, ITx has been mainly performed in patients who developed life-threatening complications attributed to IF and/or long-term TPN. In 2000, Medicare defined failure of TPN as impending or overt liver failure (elevated serum bilirubin and/or liver enzymes, splenomegaly, thrombocytopenia, gastroesophageal varices, coagulopathy, stomal bleeding, hepatic fibrosis or cirrhosis), thrombosis of two or more central veins, frequent and severe central venous catheter (CVC)-related sepsis and frequent severe dehydration [13]. In addition, other conditions associated with early death despite optimal TPN, such as congenital mucosal disorders and ultra-short bowel syndrome, are also included as per American Society of Transplantation guidelines [14].

The European guidelines recommend TPN as primary treatment for patients with IF, with early referral to specialist centers for optimal rehabilitative therapy and timely assessment of suitability for ITx. It recommends assessment for candidacy for transplantation for the presence of one or more indications parallel to American guidelines (failure of TPN, high risk of death attributable to underlying disease and IF with high morbidity or low acceptance of TPN) resulting in rates of transplant of 62, 26 and 12%, respectively [15]. Because of a statistically significant increased risk of death on TPN from liver failure due to IFALD and invasive intra-abdominal desmoids, direct referral for ITx should be considered [16]. IFALD is partly caused by omega-6 fatty acids in TPN formulas, which can be synthesized into inflammatory molecules. IFALD can range from steatohepatitis, cholestasis or hepatic fibrosis to end-stage liver disease. Children are more likely to have cholestatic liver disease than steatohepatitis [17]. Severe liver injury has been reported in as many as 50% of patients with IF who receive TPN for longer than 5 years; this is typically fatal. If patients have life-threatening infections, IFALD, or lose their venous access, 1-year mortality is 70% without ITx [18]. Conversely, patients with CVC-related complications or ultra-short bowel syndrome did not have an increased risk of death on TPN and no patients considered to be an ITx candidate with poor quality of life (QoL) or chronic dehydration actually died while remaining on TPN. This notable finding forms the basis of non-indications in previous European guidelines [19]. Despite very limited evidence exploring the role of quality of life (QoL) as an indicator for ITx, this holistic aspect may also be factored in the decision-making process [20] (**Table 2**).


**1.** Small bowel transplant only (SBTx) (**Figure 1**): recommended for people with IF who have not developed liver disease. The arterial supply to the allograft is secured with anastomosis between the donor's superior mesenteric artery (SMA) and the recipient's infrarenal aorta; venous drainage is either onto the IVC or the recipient's portal vein (PV) or superior

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**2.** Liver and small bowel transplant (SBLTx) (**Figure 2**): recommended for people with IF who also have advanced liver disease and extensive portomesenteric venous thrombosis precluding liver transplantation alone. The inclusion of a liver graft in combined liver-

**3.** Multivisceral transplant (MVTx) (**Figure 3**): recommended for people with multiple organ failure and involves transplanting the stomach, pancreaticoduodenal complex, liver and

**4.** Modified multivisceral transplant (MMVTx) (**Figure 4**): recommended for people with multiple organ failure and involves transplanting the stomach, pancreaticoduodenal complex and small bowel. The difference with the previous type is the exclusion of the liver. It is usually performed in patients with preserved liver function and coexisting pancreatic insufficiency such as patients with chronic pancreatitis, type I diabetes mellitus or cystic fibrosis, patients with intestinal dysmotility with concomitant severe gastroparesis and in cases with tumor involvement of the mesentery or the duodenum (e.g. in Gardner's

small bowel transplant has been associated with improved survival rates [21].

mesenteric vein (SMV) at the root of the mesentery.

small bowel.

syndrome) [22].

**Figure 1.** Small bowel transplant (SBTx).

**Table 2.** Intestinal transplantation guidelines.
