Congenital absence of the portal vein (CAPV) is an uncommon venous anomaly characterized by the direct drainage of mesenteric venous blood into the systemic circulation. Most patients with CAPV typically do not exhibit any manifestations of portosystemic encephalopathy, with only slight deviations in liver function test results observed. Liver transplantation (LT) becomes a consideration for patients experiencing symptomatic CAPV that does not respond to conventional medical interventions [1-4].

Congenital portocaval shunt (PCS) is a condition in which the entire mesenteric venous blood is diverted either directly into the inferior vena cava (IVC) or through the left renal vein via the splenorenal shunt, thus preventing the development of portal hypertension and collateral circulation [3-5]. However, in certain cases of CAPV, patients may exhibit manifestation of portal hypertension. When conservative medical interventions prove ineffective, the consideration of LT becomes pertinent. Patients with CAPV typically maintain relatively stable liver function profiles, often resulting in low Pediatric End-stage Liver Disease scores. Given the exceptionally limited availability of deceased donor LT in the current setting of Korea, it becomes imperative to grant priority to CAPV patients for living donor liver transplantation (LDLT).

Optimal reestablishment of portal inflow stands as the paramount factor in LT for CAPV patients, emphasizing the significance of tailoring portal vein (PV) reconstruction on a case-by-case basis to ensure the achievement of a successful LT outcome. In this context, we present a compelling case of pediatric LDLT featuring the utilization of a left lateral section (LLS) graft combined with a pericholedochal collateral vein anastomosis for the management of CAPV.

A 3-year-old boy was referred to our hospital due to palpable mass at the left upper abdomen. He was born in full-term spontaneous vaginal delivery. He had been doing well for 2 years after birth. Imaging studies showed PV occlusion with cavernous transformation, splenomegaly and esophageal varices, suggesting CAPV (Fig. 1). He was diagnosed with hepatopulmonary syndrome grade 2.

Figure 1. Pretransplant computed tomography findings of the recipient. (A–C) The native portal vein was absent with the development of cavernous, transformed collateral veins along the common bile duct. (D) The hepatic arteries appeared normal without noticeable anatomical variation.

Timely allocation for deceased donor LT was not expected in the Korean setting due to the low Pediatric End-stage Liver Disease score. Thus, we decided to perform LDLT at the age of 3 years 2 months with a body weight of 14 kg and a height of 99 cm.

The donor was the 35-year-old father of the patient. The volume of the LLS was measured as 282 mL on computed tomography volumetry (Fig. 2), thus we decided to use an LLS graft.

Figure 2. Computed tomography findings of the donor before donation surgery (A) and at one week after donation of the left lateral section (B).

An LLS liver graft was harvested, with a graft weight of 270 g at the back table, equivalent to a graft-to-recipient weight ratio of 1.93%. There was a small superficial left hepatic vein branch, which was unified with the left hepatic vein orifice to make a large graft outflow vein [6,7].

The recipient operation was performed according to the standard procedure of pediatric LDLT. During hepatic hilar dissection, the recipient’s native PV was absent with cavernous-transformed pericholedochal collateral veins. The recipient hepatic artery branches were meticulously dissected. There were two sizable pericholedochal collateral veins, thus we decided to use them as a portal inflow source. The orifice of the common bile duct was securely closed with 6-0 Prolene, and then these two collateral veins were longitudinally unified to make a left half wall of the portal inflow vein (Fig. 3). A cold-preserved fresh iliac vein allograft was attached to the collateral vein stump, thus becoming the right half wall of the portal inflow vein through the modified patch-conduit venoplasty (Fig. 4) [8]. The blood flow from this PV conduit was pouring out but not brisk.

Figure 3. Intraoperative photographs of the recipient hilar dissection. (A) The portal cavernous collateral veins were isolated with closure of the common bile duct. (B–D) Two collateral veins were incised and unified to make a left half wall of the portal vein conduit.

Figure 4. Intraoperative photographs of modified patch-conduit venoplasty to make a portal vein conduit. (A–C) An iliac vein homograft was attached to make a right half wall of the portal vein conduit. (D) The portal vein conduit was clamped after excision of the redundant vein homograft.

After supra- and infra-hepatic clamping of the IVC, the native liver was removed. After unification of the three hepatic vein orifices, the graft outflow vein was reconstructed using 5-0 polydioxanone (PDS; Ethicon) (Fig. 5). Conventional PV reconstruction using a single 6-0 PDS was performed (Fig. 6). Thereafter, graft reperfusion was initiated. Coronary collateral veins and a splenorenal shunt vein were directly ligated after separate isolation. Surgical microscopy was used for the reconstruction of the graft left hepatic artery.

Figure 5. Intraoperative photographs of graft outflow vein reconstruction (A–C) The hepatic vein orifices were unified to make a large single orifice. (D) The graft outflow vein was anastomosed using 5-0 PDS continuous sutures.

Figure 6. Intraoperative photographs of graft portal vein reconstruction using the newly made conduit. (A, B) The portal vein conduit was anastomosed using a 6-0 PDS. (C, D) The reconstructed portal vein conduit showed a large diameter.

Intraoperative Doppler ultrasonography showed thrombus formation at the reconstructed PV conduit. A small incision was applied and thrombus was removed. However, PV thrombus was observed again during observation with Doppler ultrasonography. We thought that the PV conduit was thrombogenic combined with sluggish portal blood flow, thus we decided to reconstruct PV inflow with direct anastomosis to the pericholedochal collateral veins after removal of the reconstructed conduit. The orifices of two pericholedochal collateral veins were unified with 7-0 polypropylene (Prolene; Ethicon), in which the unified diameter was as small as 5 mm. This orifice was anastomosed with the graft PV orifice with size discrepancy greater than 3 times (Fig. 7). Doppler ultrasonography showed a tight anastomotic narrowing of the PV with definitely high velocity difference across the anastomosis (41 cm/sec vs 126 cm/sec) (Fig. 8). This redo PV reconstruction took approximately 60 minutes under maintenance of the hepatic artery flow. Roux-en-Y hepaticojejunostomy was performed for biliary reconstruction.

Figure 7. Intraoperative photographs of graft portal vein reconstruction using a new orifice using the unified pericholedochal collateral veins. (A) The portal vein conduit was complexly excised (bidirectional arrow) and two pericholedochal collateral veins were unified to make a single orifice. (B) A newly created orifice was used for portal vein reconstruction. (C, D) The reconstructed portal vein showed an anastomotic stenosis.

Figure 8. Doppler ultrasonography taken at one day after transplantation. (A) A long anastomotic stenosis was identified (arrow). (B) High velocity difference was measured across the portal vein anastomosis.

The pathology report of the explant liver showed irregular narrowing and dilatation of PVs with herniation into the hepatic parenchyma, fibrous widening of the large portal tracts, and alternative atrophy and regeneration of hepatocytes, thus being suggestive of portosinusoidal vascular disease (hepatoportal sclerosis) (Fig. 9). These findings were consistent with the pathologic changes associated with CAPV.

Figure 9. Gross photograph of the explant liver.

The patient and donor recovered from the LDLT operation. Follow-up imaging studies showed diffuse narrowing of the PV anastomosis with progressively more visible lumen (Fig. 10).

Figure 10. Fig. 10 . Posttransplant computed tomography scan taken at four days after transplantation. (A) Uneventful anastomosis of the graft hepatic vein was identified. (B–D) A marked anastomotic stenosis was identified at the reconstructed portal vein (arrows).

At 40 days after LDLT operation, percutaneous balloon angioplasty was performed through segment III PV. The pressures at the PV collaterals and intrahepatic PV were 30 mmHg and 16 mmHg, respectively, before angioplasty. These were changed to 21 mmHg and 17 mmHg, respectively, after angioplasty (Fig. 11).

Figure 11. Fig. 11 . Percutaneous transhepatic angioplasty taken at 40 days after transplantation. (A) A puncture was made through the segment III porta vein branch. (B) The remained portal collateral veins were markedly engorged. (C) A marked anastomotic stenosis was identified (arrow). (D) Balloon angioplasty was performed to dilate the anastomotic stenosis (arrow).

Doppler ultrasonography taken at 2 months after LDLT showed improved but remained PV narrowing with a velocity difference across the anastomosis (65 cm/sec vs 125 cm/sec). This patient has been doing well for 3 months after the LDLT.

CAPV is an uncommon venous anomaly characterized by the direct diversion of mesenteric venous blood into the systemic circulation. PCS manifest in two distinct forms: intrahepatic PCS, which is situated between the PV and hepatic veins [9], and extrahepatic PCS, which is further categorized into type I and type II based on the presence of intrahepatic portal venous supply [10]. Type I PCS represents an extrahepatic shunt without a patent intrahepatic PV, resulting in the entirety of mesenteric venous blood flow emptying directly into systemic veins, including the IVC and the left renal vein. This specific subtype is identified as CAPV. In contrast, type II PCS constitutes an extrahepatic shunt characterized by a patent intrahepatic PV. Our present patient presented type I PCS, with development of variceal collateral veins.

The standard treatment for CAPV has not yet been established. Although PCS can be accompanied by hyperammonemia, the majority of the patients with PCS show no signs of hepatic encephalopathy. Such patients show only slightly abnormal liver function test results. Our present patient showed only mild elevation of liver enzymes. The majority of patients with CAPV receive conservative medical treatment for hyperammonemia, while only a small portion of patients with CAPV require surgical treatments, including LT. Surgical treatment is indicated when hyperammonemia or portosystemic encephalopathy is refractory to medical treatment [11,12].

Pretransplant imaging examinations conducted on patients with CAPV reveal the presence of a significant connecting vein between the splenorenal shunt and the IVC. These imaging studies, as well as intraoperative observations, have not yielded any manifestations of portal hypertension. However, it is important to note that we have previously documented two unusual instances of CAPV cases that exhibited symptoms of portal hypertension [13,14]. In the present case, as in our previous cases, portal hypertension and collateral veins were observed.

Since surgical reconstruction of the PV structures of the native liver is impossible, LT is indicated for most patients with type I PCS. Although LT for symptomatic CAPV has been reported in the literature [1-3,5,12,14-19], techniques for PV reconstruction have not yet been well established. There are two methods of PV reconstruction in LT for CAPV. The first method is to anastomose the PCS directly to the graft PV in an end-to-end fashion [2,17]. The second method is to use a venous interposition graft through an end-to-side anastomosis to the PCS [3,5]. In our previous four CAPV cases, the PV stump was absent [13,15,16,20], thus direct anastomosis was technically impossible. Therefore, we used vein conduit interposition as an end-to-side anastomosis to the PCS. This method was initially performed in the present case, but the PV conduit was occluded with thrombus formation. As a rescue method, we performed direct anastomosis with the pericholedochal collateral vein after resection of the reconstructed PV conduit. We previously performed direct anastomosis with the PV collateral vein in a pediatric patient with CAPV [21]. We previously reported PV reconstruction with pericholedochal collateral vein in an adult LDLT case [22].

In the present case, we opted not to conduct intraoperative cineportography due to direct ligation of collateral veins immediately following their identification through pretransplant computed tomography images. An intraoperative splanchnic venogram served as a precise guide for planning the PV reconstruction and the subsequent interruption of collateral drainage [23].

A definite anastomotic stricture developed because of a significant size difference between the graft PV and the unified pericholedochal collateral veins. Subsequent Doppler ultrasonography follow-ups demonstrated gradual improvement in the PV stenosis at the anastomotic site, although a definite stricture persisted. After 40 days post-LDLT, a percutaneous balloon angioplasty procedure was performed to address the anastomotic PV stenosis, resulting in a noticeable expansion of the narrowed PV anastomosis [24,25].

In conclusion, given the diverse presentations of PCS in CAPV patients, it is imperative to tailor the PV reconstruction approach, whether involving homograft vein interposition or not, based on a comprehensive anatomical assessment both prior to and during LT operation.

There was no funding related to this study.

All authors have no conflicts of interest to declare.

Conceptualization: JMN, SH. Data curation: All. Formal analysis: SH. Investigation: All. Methodology: SH, GCP, SK, KMK, SHO. Project administration: SH. Resources: SH. Supervision: SH. Validation: SH. Visualization: JMN, SH. Writing – original draft: All. Writing – review & editing: JMN, SH, GCP.