Middle hepatic vein (MHV) reconstruction with an interposition vessel graft has been established as a standard procedure for living donor liver transplantation (LDLT) using a right lobe graft when the donor’s MHV trunk is preserved in the donor’s remnant liver. Although large-size vein allografts are suitable for MHV reconstruction, their supply is often limited. Various synthetic vascular grafts (SVGs) have been frequently used due to their availability and high patency rates [1-3]. However, unwanted migration of an SVG into the hollow viscus is an unexpected serious complication [3,4]. Its real-world 5-year incidence has estimated to be 2% in a single-center study [5]. Majority of occluded SVGs remain silent as foreign bodies after thrombotic luminal obliteration, which could potentially cause other rare complications. Migration of SVGs into the stomach or duodenum can induce life-threatening complications that require surgical removal. The aim of this study was to review worldwide cases of SVG migration into the hollow viscus following LDLT.

The objective of the study was to analyze computed tomography (CT) appearance and clinical features of adjacent organ injuries related to polytetrafluoroethylene (PTFE) grafts after LDLT. Authors evaluated follow-up CT images of 204 patients who underwent venoplasty with PTFE during LDLT and encountered 4 (1.96%) patients with adjacent organ injuries related to PTFE. Clinical imaging records were reviewed in terms of imaging findings and possible risk factors. In three patients, PTFE graft perforated gastric antrum or duodenal bulb. In another patient, the common bile duct was injured. The mean interval between transplantation and identification of injury was 30 months. In patients had adjacent organ injuries, biliary or perihepatic interventional treatments, adhesion of bowel and early occlusion of PTFE grafts were commonly observed. Authors concluded that adjacent organ injuries by PTFE graft after LDLT were rare but possible. Interventional procedures, adhesion of the bowel wall, and early occlusion of graft were possible risk factors [6].

During the study period of 30 months, we performed 215 cases of LDLT with modified right lobe graft and MHV reconstruction using PTFE graft. Authors classified potential complications directly associated with PTFE graft interposition as infectious and surgical complications. MHV graft patency rate was 76.3% at 6 months and 36.7% at 12 months. One-year liver graft and patient survival rates were 92.6% and 93.5%, respectively. One-year actual incidences of infectious complication and surgical complication were near zero and 0.5% (1 case), respectively. In one recipient, the PTFE graft penetrated into the stomach wall at six months after transplantation, although the patient did not complain of any specific symptoms. After the PTFE graft was removed by laparotomy, the patient recovered uneventfully. The authors suggested that, although the incidence of PTFE graft–associated complication rate is very low, it is necessary to closely monitor the PTFE graft because unexpected complications can happen during a long-term follow-up [3].

From January 2012 to October 2015, a total of 397 patients underwent LDLT. PTFE vascular grafts were used during back table venoplasty for outflow reconstruction in 262 of liver allografts. PTFE-related complications developed in 4 (1.52%) patients. One (0.38%) patient developed complete thrombosis with sepsis at 24 months post-transplantation and died due to multiorgan failure. Three (1.1%) patients developed graft migration into the second portion of the duodenum without overt peritonitis. Surgical exploration and PTFE graft removal was done in all patients. One patient died due to overwhelming sepsis. The authors have concluded that PTFE graft migration into the duodenum causing perforation is a new set of complications that has been recently described in LDLT and can be treated effectively by surgical removal of the infected vascular graft and duodenal perforation closure. Despite such complications, PTFE use in LDLT continues to have a wide safety margin with a complication rate of only 1.52% [4].

Authors analyzed patency rates of PTFE-interposed MHV in 100 LDLT recipients and reviewed complications including PTFE graft migration. The mean age was 53.5±5.4 years and the male to female ratio was 73:27. Primary diagnoses were hepatitis B virus infection (n=71) and others (n=28). Mean model for end-stage liver disease score was 16.2±8.3. V5 reconstruction was performed as either single anastomosis (n=85) or double anastomoses (n=14). No V5 reconstruction was required for one patient. V8 reconstruction was performed as single anastomosis, double anastomoses, and no reconstruction in 75, 0, and 25 patients, respectively. During a mean follow-up of six years, three recipients required early MHV stenting within two weeks. After three months, there were no episodes of congestion-associated infarct regardless of MHV patency. Patency rates of PTFE-interposed MHV were 54.0%, 37.0%, and 37.0% at 1, 3, and 5 years, respectively. Unwanted PTFE graft migration occurred in two recipients. Actual incidence was 2% at 5 years. Authors concluded that PTFE grafts combined with small artery patches demonstrated acceptably high short- and long-term patency rates. Since the risk of unwanted migration of PTFE graft is not negligibly low, lifelong surveillance is necessary to detect unexpected rare complications [5].

A 59-year-old male patient with end-stage liver disease underwent LDLT utilizing a right hemi-liver graft. Drainage of segment V vein was done to the inferior vena cava using a vascular graft. Graft patency was confirmed by regular follow-up Doppler ultrasound. Graft thrombosis was detected in the 4th month postoperatively. The patient developed anastomotic biliary stricture three months after LDLT, which required repeated endoscopic retrograde cholangiopancreatography (ERCP). During ERCP at two and half years after LDLT, the thrombosed graft was seen eroding into the first part of the duodenum. The patient was generally stable and the decision was to follow-up the condition. Follow-up CT showed disappearance of the graft from the abdomen and endoscopy revealed a small ulcer at the site of the migrated graft. The authors reported a rare case of spontaneous migration of thrombosed SVG into the duodenum after LDLT [7].

Authors present results of two patients with vascular graft migration to the duodenum after liver transplantation. In the authors’ center, 201 liver transplants were performed, including 154 with a right lobe LDLT. A synthetic graft was used to reconstruct segment 5 and 8 hepatic veins in 78 of the 154 LDLTs. During a mean follow-up 19.6±12.1 months (range, 1–44 months), graft migrated to the duodenum in two patients. Contrary to the literature, these patients were followed non-operatively. No problem was observed in the follow-up process. Authors concluded that, in patients with vascular graft migration to the duodenum after living liver transplantation, non-operative follow-up could be performed in appropriate patients [8].

Clinical, radiological, and endoscopic data of 13 right lobe LDLT patients aged 26 to 67 years with a diagnosis of postoperative SVG migration n into adjacent hollow viscus were analyzed. Biliary complications were detected in 12 patients. A median of four times of ERCP procedures were performed in 11 patients prior to SVG migration diagnosis. A median of 2.5 times of various percutaneous radiological interventional procedures were performed in eight patients prior to SVG migration diagnosis. The site of migration was the duodenum in eight patients, gastric antrum in four, and Roux limb in the remaining one patient. Migrated SVG was made of PTFE in 10 patients and polyethylene terephthalate (Dacron) in three. Migrated SVGs were endoscopically removed in seven patients and surgically removed in six. Only one patient died due to sepsis unrelated to SVG migration. Authors concluded that SVG migration into the adjacent hollow viscus following right lobe LDLT was a rare and serious complication. Repetitive ERCP, interventional radiological procedures, infection related to biliary leakage, and thrombosis of SVGs were possible risk factors [9].

In LDLT of the right lobe, PTFE grafts might be used for anterior drainage. This study aimed to determine risk factors of PTFE graft-associated complications. Data from patients who underwent LDLT of the right lobe with MHV reconstruction using PTFE grafts between January 2005 and December 2012 were retrospectively reviewed. Among 360 patients, PTFE graft-associated complications occurred in 17 (4.7%) patients (group B). Recipients (95.3%) without these complications comprised group A. Group B showed significantly lower 1-, 6-, and 12-months patency rates (p<0.001, p=0.002, and p=0.007, respectively). In group B, eight (47.1%) patients required surgical intervention, three (17.6%) patients suffered from infectious complications, and 14 (82.4%) patients experienced PTFE graft migration into adjacent organs, including the common bile duct (n=3, 17.6%), stomach (n=1, 5.9%), duodenum (n=5, 29.4%), and jejunum (n=5, 29.4%). The proportion of recipients who underwent hepaticojejunostomy, had abdominal adhesions, and received interventions in/around the liver after LDLT was higher in group B (p<0.001). Thus, although the incidence of PTFE graft-associated complication is low, close long-term follow-up is needed, especially in patients with risk factors [10].

Authors present a case of Hemashield graft migration into the duodenum following LDLT. A 64-year-old male patient underwent LDLT due to liver cirrhosis and hepatocellular carcinoma. The MHV openings at the right liver graft were reconstructed with a 10 mm-sized Hemashield graft, which was anastomosed to the common opening of the recipient middle-left hepatic vein trunk. The patient recovered uneventfully after LDLT operation. CT scans taken at 1 year and 2 years showed no abnormal finding. However, gastroduodenoscopic examination at 2 years revealed accidental migration of Hemashield graft into the duodenal bulb. The patient had no symptoms and signs, with no problem in diet. Migration of Hemashield graft was identified through retrospective review of the 1-year and 2-year CT scans primarily due to no radio-opacity of Hemashield grafts. Because of potential complication from migration of the Hemashield graft, but the patient wanted to observe further. The patient has been doing well for two and half years after LDLT at the time of writing [11].

MHV reconstruction has resulted in a new demand for vascular allografts in the field of LDLT. Moreover, the increase in LDLT volume can lead to relative shortages in the supply of vessel allografts. Regarding availability, SVGs have a definite merit of unlimited supply. Short- and long-term patency rates of PTFE grafts are acceptably high [5]. However, unwanted migration of a SVG into the hollow viscus is an unexpected serious complication.

Since its first report in 2011, there are at least nine case reports or short series of in SVG migration following LDLT the literature, although some of them are overlapped [3-11]. It has been hypothesized that acute thrombotic occlusion of the PTFE graft can increase peri-graft inflammation, which in turn can increase adhesion of the graft to an adjacent organ, thereby promoting graft migration [4,5]. Although occlusion of SVGs did not compromise the function of the transplanted liver, such occlusion is associated with organ injuries caused by SVGs.

Postoperative complications and interventional treatments undertaken are other influencing factors of SVG-associated complications. In several cases with biliary complications and perihepatic fluid collection or hematoma formation after LDLT, repeated percutaneous or endoscopic interventional treatments were undertaken. These treatments might have distorted the shape and location of the SVG [10]. Some studies have reported that postoperative insertion of interventional devices into the biliary tract, perihepatic space, or bowel plays a major role in the causation of thrombotic synthetic graft-associated injuries to adjacent organs [6,7]. Another study has shown significant differences in the incidence of percutaneous transhepatic biliary drainage, endoscopic retrograde biliary drainage and percutaneous drainage catheter insertion between the group with SVG-associated complications and the group without these complications [10]. Thus, it is necessary to pay close attention to potential SVG injuries when performing perihepatic procedures for posttransplant complications. Intraabdominal adhesion findings and hepaticojejunostomy should also be considered as new risk factors of PTFE graft-associated complications in LDLT patients. To prevent unexpected infection and organ injury due to PTFE grafts, further precautions should be taken when these risk factors are identified [10].

Because SVG-associated complications could be easily detected on CT images, contrast-enhanced CT is the best modality for early detection of SVG-related complications, including infection and suspected gastrointestinal tract penetration. In contrast, accidental SVG migration was missed on follow-up CT scans in a patient using a Hemashield graft probably due to no radio-opacity of Hemashield grafts [11]. Special attention should be paid during CT interpretation when non-radio-opaque SVG was used. Endoscopic evaluation of the stomach, duodenum, and other adjacent structures should be performed next [3,10]. Clinical signs and symptoms are dependent on injured organs and the extent of injury. In cases of fever or abdominal discomfort of unknown etiology and abnormal laboratory values of the liver function tests, it is necessary to suspect SVG-associated complications.

There is no definite consensus for the treatment of SVG migration into the hollow viscus to date. The majority of patients underwent definitive treatment including surgical removal. However, some patients without any symptoms or signs were under close observation at the time of writing.

Considering benefits and complications of SVGs, grafts are currently regarded as vascular substitutes of “necessary evil.” Considering that massive hepatic venous congestion from exclusion of MHV deprivation is one of the leading causes of graft failure, the demerits from SVG-associated complications are not great enough to abandon the use of SVG grafts [1,5].

In conclusion, the risk of unwanted migration of SVG used for MHV reconstruction is not negligibly low. Lifelong surveillance is necessary to detect unexpected rare complications in LDLT recipients with MHV reconstruction using SVG.

There was no funding related to this study.

All authors have no conflicts of interest to declare.

Conceptualization: YKC. Data curation: CSP. Formal analysis: CSP. Investigation: YKC. Methodology: All. Validation: YKC. Writing – original draft: All. Writing – review & editing: All.