1 Introduction

Intestine transplant refers to a collection of transplant surgeries used to address significant challenges with abdominal anatomy and physiology. The small intestine with or without the colon may be transplanted alone or in combination with the liver. Foregut organs such as the stomach, duodenum, and pancreas may be added to these base transplants to add to the versatility of these procedures. The variability seen in intestine transplant, whether it be diagnoses, complications, or outcomes, may be attributable to these varied surgeries functioning under one name. Even combining all of these into a single category of intestine transplant results in only small numbers of candidates and recipients compared with other forms of organ transplant, so drawing rigorous inferences is inherently limited. In this report of intestine transplant activity in the United States, we review the latest full year of data through 2024 and note some interesting trends.

First, intestine transplant numbers are no longer declining. For years, the number of intestine transplants performed in the United States had been falling, largely attributed to the advances in intestinal rehabilitation. These advances have allowed children and adults receiving parenteral nutrition to avoid complications that necessitate transplant, such as advanced liver disease or recurrent sepsis. While the care of children with intestinal failure has allowed for fewer early transplants, we continue to see a greater number of adult intestine transplants. Notably, these adult transplants do not seem to be for pediatric diagnoses. In other words, adults are developing intestinal failure later in life and pursuing transplant, rather than children with intestinal failure simply surviving long enough that they are adding to the adult intestine transplant numbers. This may be due to both expanding indications for specifically multivisceral transplant (eg, mesenteric thrombosis or tumor) and the challenges experienced by adult patients with intestinal failure in identifying the level of centralized care provided to pediatric patients.

Second, waitlist mortality for intestine-without-liver (ie, isolated) transplant has been essentially eliminated. A few patients were removed from the list for becoming too sick for transplant, but no deaths occurred on the waiting list in 2024. This contrasts to the mortality associated with intestine-with-liver transplant, where 14.6% of listed patients died within 3 years from listing. Indeed, for adults awaiting intestine-with-liver transplant, the mortality rate in 2024 of 15.0 deaths per 100 patient-years exceeds the pretransplant mortality rate for those awaiting liver transplant, which was reported in the previous Annual Data Report as 12.9 deaths per 100 patient-years. On the other hand, in 2024, pediatric candidates on the intestine-with-liver waiting list had a mortality rate of 5.4 deaths per 100 patient-years, similar to the mortality rate in pediatric liver candidates. These data speak to the critical need to study morbidity in this population. Intestine-without-liver transplant needs to be considered as a treatment for morbidity associated with parenteral nutrition, even if it is not being used to immediately prevent mortality. Of course, intestine-without-liver transplant may prevent individuals from developing liver disease and requiring an intestine-with-liver transplant at all. Alternatively, the low numbers of waitlist deaths for intestine-without-liver transplant candidates may represent the fact that the most common indication leading to listing for intestine transplant is loss of central venous access. When this loss of access becomes severe enough to risk mortality in a patient, it likely has also become severe enough to technically preclude transplant due to an inability to establish upper extremity access. While these reports have historically focused on an underlying diagnosis, examining the actual indications for transplant remains a critical need that may be met in future Annual Data Reports.

Lastly, improving intestine transplant outcomes continues to be a key area of focus. Intestine transplant outcomes have remained unchanged for the past decade. In adult recipients of transplants in 2017-2019, intestine-with-liver transplant graft survival at 1 year barely exceeded 50% while 54.5% of intestine-without-liver recipients had surviving grafts at 5 years. As previously discussed, these differences are unlikely to represent the progression of disease between those requiring transplant without versus with liver as it might in pediatric recipients. Instead, this represents the array of diagnoses being treated with multivisceral transplant that may lend itself to poorer outcomes. In other words, adult intestine-without-liver transplant and adult intestine-with-liver transplant represent completely different patient populations that are difficult to compare. In children, it is more likely that intestine-with-liver transplant is pursued for liver disease from parenteral nutrition rather than alternative diagnoses. As such, these pediatric patients have similar outcomes to those receiving intestine-without-liver transplant. In fact, pediatric intestine-with-liver recipients (2017-2019) had slightly higher 5-year graft survival (60.5%) than pediatric intestine-without-liver recipients (54.3%). While this has been proposed to reflect an immunoprotective effect of the liver, the immune benefit may go beyond rejection, as posttransplant lymphoproliferative disorder (PTLD) rates were 50% lower in those receiving intestine-with-liver transplant.

In summary, intestine transplant may best be described as a series of surgical techniques to improve the lives of those with severe gastrointestinal and mesenteric disease. The following data represent an overall snapshot of the sum of these procedures, now being performed for more than just failure of parenteral nutrition.

2 Waiting List

The number of intestine waitlist additions remained stable in 2024 at 128 new candidates, compared with 135 new additions in 2023. New intestine-with-liver listings exceeded the intestine-without-liver listings for the first time in 3 years (Figure IN 1). These additions continued to result in more candidates waiting for intestine-with-liver transplant, which has been a steady trend for the past 4 years (Figure IN 2). Over those same 4 years, most (60%) intestine transplant candidates on the waiting list were aged 18 years or older (Figure IN 3). The slight male predominance (52.5%) of waitlisted candidates in 2024 has been consistent for the past 12 years (Figure IN 4). In 2024, candidates were 58.1% White, followed by 20.4% Hispanic, 15.3% Black, 4.7% Asian, and less than 1% each for Multiracial, Native American, and unreported (Figure IN 5). New in this 2024 report, the causes of congenital short-gut syndrome (SGS) have been separated, which reveals a recent trend of decreasing waitlist candidates for gastroschisis (Figure IN 6). The other/unknown diagnosis category continued to increase and accounted for 33.9% of all intestine candidates on the waiting list on December 31, 2024 (Table IN 2). Otherwise, SGS continued to be the most common, encompassing noncongenital SGS (31.2%), necrotizing enterocolitis (9.5%), gastroschisis (7.9%), intestinal atresia (4.8%), Hirschsprung disease (4.2%), and volvulus (2.6%). Pseudo-obstruction accounted for the remaining 5.3% with 1 waitlist candidate listed for enteropathy. The 64 candidates listed as other/unknown included write-in diagnoses of 24 with portal venous/mesenteric thrombosis, 5 with tumors, 4 with other forms of SGS, and 17 with a primary dysmotility disorder. After several years of a decreasing trend, the percentage of intestine-without-liver candidates who have been waiting for 2 years or longer increased (Figure IN 7), reaching 36.5% at the end of 2024—nearly matching the 39.1% for those waiting as long for an intestine-with-liver transplant (Figure IN 8 and Table IN 3).

Candidates waitlisted for intestine-without-liver or intestine-with-liver transplant were similar in terms of age distribution (Table IN 1). Substantially more male candidates were listed for intestine-with-liver transplant compared to intestine-without-liver transplant. Race distributions were similar between the two groups, but a slightly higher percentage of those listed for intestine-with-liver transplant were identified as Hispanic. Most candidates came from metropolitan areas, although the percentage was higher among those listed for intestine-with-liver transplant. For both groups together, 28.0% of candidates were listed at centers 250 or more miles away. An other/unknown diagnosis was more commonly reported among those awaiting intestine-with-liver transplant, by almost twice as much percentagewise (Table IN 2). The most common diagnosis for those awaiting intestine-without-liver transplant was noncongenital SGS. Blood types were similarly distributed between both types of candidates. Eight (10.8%) candidates on the intestine-without-liver list and 17 (14.8%) on the intestine-with-liver list had received a previous intestine transplant (Table IN 3).

Adult intestine transplant candidates listed for intestine-without-liver and intestine-with-liver transplant returned to similar percentages in 2024 (Figure IN 9). This differs from the pediatric population, where the percentage listed for intestine-with-liver transplant continued to increase to 63.6% in 2024 (Figure IN 10).

Newly shown in this 2024 report, the percentage of listed candidates who were active on the waiting list has remained stable at 68.4% (Figure IN 11).

Rates of intestine transplant have remained relatively constant since 2019 in adult candidates, with waitlisted individuals having received intestine transplants at a rate of 55.7 transplants per 100 patient-years in 2024 (Figure IN 12). Although the pediatric transplant rate for listed candidates remained lower than the adult rate, it continued to increase, reaching a 12-year high in 2024 of 39.5 transplants per 100 patient-years (Figure IN 13). Transplant rates were comparable across the adult age groups in 2024 (Figure IN 14). The decreasing trend in transplant rate for candidates younger than 1 year changed in 2024 (Figure IN 15), likely due to the small number of candidates in this age range. Transplant rates of waitlisted candidates of all ages identified as Black or Hispanic were similar to those of White candidates in 2024, reversing a trend toward lower transplant rates in these populations seen over the previous several years (Figure IN 16). For the fourth consecutive year, transplant rates were higher for those without liver colisting (61.1 transplants per 100 patient-years) compared to those with liver colisting (39.7 transplants per 100 patient-years) (Figure IN 17).

A review of waitlist activity over 2024 shows that 75 patients were removed from the intestine-without-liver list with only 54 new additions, resulting in a decreased total of these candidates on the waiting list from 95 to 74 over the year (Table IN 4). For intestine-with-liver candidates, additions (n = 74) nearly equaled the number of removals (n = 75), resulting in essentially no change to the total number waiting for intestine-with-liver transplant: 116 to 115. No candidates awaiting intestine-without-liver transplant died on the waiting list, but three were removed from the list for being too sick for transplant (Table IN 5). Eleven candidates awaiting intestine-with-liver transplant died, and an additional two candidates were removed from the list for being too sick for transplant.

Three-year outcomes for intestine-without-liver transplant candidates showed an improvement in transplant rate from the previous (2023) report; for candidates listed in 2019-2021, 75.3% received a transplant, 4.5% died, 12.4% were removed from the waiting list for other reasons, and 7.9% remained on the list (Figure IN 18). The opposite was the case for those awaiting intestine-with-liver transplant and listed during that period: 50.9% received a transplant (down from 62.8% in the 2023 report [for those listed in 2018-2020]), 14.6% died (up from 10.2% in 2023 report), 19.8% were removed from the waiting list for other reasons, and 14.6% remained on the list (Figure IN 19). Mortality rates for waitlist candidates by race and ethnicity appear stable from 2023 to 2024, despite relatively unstable data due to the small numbers (Figure IN 20). Although the numbers remained small, for the third consecutive year, the mortality rate for waitlisted male candidates was slightly higher than that for waitlisted female candidates (Figure IN 21). Consistently, the mortality rate for those awaiting intestine-with-liver transplant has been much higher (10.7 deaths per 100 patient-years in 2024) than that for those awaiting intestine-without-liver transplant (1.1 deaths per 100 patient-years in 2024) (Figure IN 22). These differences were greater for adult waitlisted candidates in 2024; the mortality rate for adults awaiting intestine-with-liver transplant was 15.0 deaths per 100 patient-years, compared with 1.9 per 100 patient-years for those awaiting intestine-without-liver transplant (Figure IN 23). Pediatric candidates have an overall lower waitlist mortality, and those awaiting intestine-with-liver transplant had a mortality rate of 5.4 deaths per 100 patient-years in 2024 (Figure IN 24). For the second consecutive year, no deaths were reported among pediatric candidates awaiting intestine-without-liver transplant.

3 Transplant

In 2024, there were 97 intestine transplants performed overall, similar to the 95 performed in 2023 and relatively unchanged since 2019 (Figure IN 25). Of the 65 adult recipients, 44 received intestine-without-liver transplant (Figure IN 26). Conversely, of the 32 pediatric recipients, only 7 received intestine-without-liver transplant (Figure IN 27). Similar numbers of total recipients were male and female, which has been consistent for the past several years (Figure IN 28). In terms of racial and ethnic distribution, the percentages of White (57.7%), Black (16.5%), Asian (3.1%), and Multiracial (1.0%) recipients have remained stable, while there was an increase in Hispanic recipients (21.6% in 2024, from 14.7% in 2023) (Figure IN 29).

For all intestine transplant recipients over the past 2 years (2023-2024), pediatric patients continued to be the majority of intestine-with-liver recipients (54.3%) but a relative minority of intestine-without-liver recipients (18.9%) (Table IN 6). Distributions by sex and by race and ethnicity were similar between the transplant types. The data on insurance type from those years reflect the higher proportion of pediatric recipients receiving intestine-with-liver transplant, as Medicaid insures most of these recipients.

As with waitlisted candidates, the most commonly reported underlying diagnosis among the 97 intestine transplant recipients in 2024 was other/unknown (32 [33.0%]) (Figure IN 30). In 2023 and 2024, most of the 111 recipients of intestine-without-liver transplants had underlying diagnoses of noncongenital SGS (48 [43.2%]), other/unknown (21 [18.9%]), volvulus (13 [11.7%]), or pseudo-obstruction (12 [10.8%]) (Table IN 7). The 81 recipients of intestine-with-liver transplant during those years most frequently had their diagnosis reported as other/unknown (35 [43.2%]), followed by noncongenital SGS (18 [22.2%]). Among the 56 transplant recipients with an other/unknown diagnosis in that period, free-text diagnoses included 15 with thrombosis, 13 with various forms of dysmotility, and 10 with neoplasms. Blood type distributions were fairly similar between transplant types.

Over the past 2 years (2023-2024), all intestine transplants performed in the United States were deceased donor transplants (Table IN 8). The most common waiting time for both transplant types was less than 90 days. However, 8.1% of intestine-without-liver recipients and 17.3% of intestine-with-liver recipients waited for 2 years or more to receive a transplant. For those 2 years, prior intestine transplants were recorded in 13 of 111 (11.7%) intestine-without-liver recipients and 12 of 81 (14.8%) intestine-with-liver recipients. In 2024, prior intestine transplant accounted for 17 of 97 (17.5%) of all intestine transplants (Figure IN 31).

Most recipients of intestine transplant come from metropolitan areas, which is reflective of US demographics, but 27.6% in 2023-2024 needed to travel 250 miles or more to reach their transplant center (Table IN 6). A majority of donors are located 250 miles or more from the transplant center, with 35 (36.1%) donors in 2024 having been 500 or more miles from the transplant center (Figure IN 32). The number of centers performing at least one intestine transplant decreased to a 10-year low of 13 centers (Figure IN 35).

New in this 2024 report, Table IN 9 summarizes the donor-recipient serology matching among transplants from 2022 through 2024. Most donors (56.2%) and recipients (58.8%) were naive to cytomegalovirus. Conversely, most donors (71.9%) and recipients (66.1%) had evidence of previous exposure to Epstein-Barr virus (EBV). Most recipients were negative for hepatitis B and C viruses. Of interest, with the availability of highly effective antiviral treatment for hepatitis C, 1.5% of donors were hepatitis C nucleic acid test positive.

4 Immunosuppression

Most intestine transplant recipients received an induction agent, although the percentage reporting induction use decreased slightly in 2024 to 81.4%, from 87.4% in 2023 (Figure IN 33). The most common maintenance regimen in 2024 was tacrolimus with both steroids and mycophenolate mofetil (35.1%), and tacrolimus plus steroids was the next most common (28.9%) (Figure IN 34).

5 Outcomes

Graft failure rates among intestine transplant recipients have remained stable over time. In the most recent cohorts, graft failure rates for intestine-without-liver recipients were 17.4% at 6 months and 26.1% at 1 year for transplants in 2023, 41.9% at 3 years for transplants in 2021, 36.7% at 5 years for transplants in 2019, and 68.8% at 10 years for transplants in 2014 (Figure IN 36). Graft failure rates for intestine-with-liver recipients were 31.3% at 6 months and 31.3% at 1 year for transplants in 2023, 64.7% at 3 years for transplants in 2021, 63.2% at 5 years for transplants in 2019, and 65.7% at 10 years for transplants in 2014 (Figure IN 37). Among adults who underwent transplant in 2017-2019, graft survival for those receiving intestine-without-liver transplant was 83.2% at 1 year and 54.5% at 5 years while graft survival for those receiving intestine-with-liver transplant was 51.9% at 1 year and 41.6% at 5 years (Figure IN 38). For pediatric recipients of transplant in 2017-2019, graft survival for those receiving intestine-without-liver transplant was 77.1% at 1 year and 54.3% at 5 years while graft survival for those receiving intestine-with-liver transplant was 82.7% at 1 year and 60.5% at 5 years (Figure IN 39). Graft survival curves were similar for those from metropolitan and nonmetropolitan areas who received transplant in 2017-2019 (Figure IN 40). In that time frame of 2017-2019, recipients of intestine-without-liver transplant had better overall survival than those of intestine-with-liver transplant. Adult recipients of intestine-without-liver transplant had overall survival of 91.0% at 1 year and 69.0% at 5 years versus recipients of intestine-with-liver transplant who had survival of 57.1% at 1 year and 46.8% at 5 years (Figure IN 41). Pediatric recipient overall survival was 88.6% at 1 year and 77.1% at 5 years in those receiving intestine-without-liver transplant and 84.0% at 1 year and 65.4% at 5 years in those receiving intestine-with-liver transplant (Figure IN 42).

Rejection is frequently reported in the first posttransplant year (Figure IN 43); about 44% of adult and pediatric recipients of intestine transplant in 2023 had acute rejection, an increase from around 19% of recipients in 2022 having rejection in the first posttransplant year.

Intestine transplant recipients experience higher rates of PTLD, possibly due to the higher immunosuppression requirements though other mechanisms may be responsible. Five-year cumulative incidence of PTLD continued to be higher in those who received intestine-without-liver transplant (6.0%) compared to those who received intestine-with-liver transplant (2.9%) (Figure IN 44 and Figure IN 45). In intestine-without-liver recipients, those who were EBV negative at transplant had a 12% 5-year incidence of PTLD versus only 4.1% in those who were EBV positive at transplant.

6 Donation

In 2024, there were 102 individuals who donated intestines for transplant (Figure IN 46). Deceased donors of intestines were most frequently younger than 18 years (54.9%; Figure IN 47 and Figure IN 48). Intestine donors were more frequently male, a trend which has persisted over the past decade (Figure IN 49). The racial and ethnic distribution of intestine donors has remained stable, with a recent slight increase in the proportion of Hispanic donors (Figure IN 50), which likely reflects changes in the national census. Head trauma and anoxic injury remained the most common causes of death in intestine donors (Figure IN 51). Only 4.9% of intestines recovered for transplant went unused (Figure IN 52), with similar rates between male and female donors (Figure IN 53).