Congenital absence of the portal vein (CAPV) is a rare venous malformation in which the mesenteric venous blood drains directly into the systemic circulation. The majority of CAPV patients show no signs or symptoms of portosystemic encephalopathy and show only abnormal liver function test results. Liver transplantation (LT) is commonly indicated for patients with symptomatic CAPV refractory to medical treatments, especially individuals with serious clinical manifestations, such as hyperammonemia, portosystemic encephalopathy, hepatopulmonary syndrome, hepatic tumors, or intractable complications [1-4].

The congenital portocaval shunt (PCS) drains the mesenteric venous blood either directly into the inferior vena cava (IVC) or through the left renal vein via the splenorenal shunt. This unique circulation pathway of the splanchnic blood flow does not induce portal hypertension, thereby preventing the development of collateral circulation [3-5]. The liver with CAPV does not have sufficient portal inflow blood; hence, the hepatic arterial flow is the main mode of blood inflow to the liver. If a CAPV patient does not respond to medical treatment, LT is indicated for prolonged survival. In a patient with CAPV, the liver function profile is not notably disturbed; thus, the pediatric end-stage liver disease (PELD) score is very low, with a very low chance of deceased donor liver transplantation (DDLT) in the current medical scenario in Korea. Thus, living donor liver transplantation (LDLT) is preferentially indicated for patients with CAPV. Herein, we present a case of pediatric LDLT using the left liver graft for CAPV with intrahepatic PCS.

The patient, who is a 3-year-old boy, was born through full-term cesarean section in our hospital owing to heart problems. At birth, cardiomegaly with patent ductus arteriosus was identified. At the age of 1 year, the patient presented with dyspnea on exertion and cyanosis; he was subsequently diagnosed with CAPV, hepatopulmonary syndrome, and pulmonary arteriovenous malformation. Lung perfusion scans showed a right-to-left shunt of 14.3%. At the age of 3 years, the hepatopulmonary syndrome progressed to stage IV, with the follow-up lung perfusion scans showing a right-to-left shunt of 24.3%. The patient also manifested autistic spectrum disorder and intellectual disability; at this time, the patient was not considered for Rex shunt operation owing to poor development of the intrahepatic portal vein system. Liver computed tomography (CT) showed prominent intrahepatic PCS with no other significant abnormalities (Fig. 1). The liver function profile was normal, thus producing a very low PELD score that did not permit DDLT. Thus, we decided to perform LDLT at the age of 3 years and 5 months on the boy whose body weight was 14 kg and height was 99 cm. The donor was the 31-year-old mother of the patient, whose left liver volume was determined to be 370 mL by donor CT volumetry.

Figure 1. Pretransplant computed tomography findings of the recipient. The extrahepatic portal vein anatomy appeared to be normal (A, C), but portocaval shunting through the inferior right hepatic vein (arrows) was identified (B, D). The anatomy of the major hepatic veins and hepatic artery appeared normal (E, F).

The recipient’s operation was performed in accordance with standard LDLT procedures. First, the enlarged inferior right hepatic vein, which was the communicating vein of PCS, was encircled (Fig. 2A); during hepatic hilar dissection, the recipient’s native portal vein was identified to be patent. The hepatic arteries were enlarged owing to portal flow deprivation-associated compensation (Fig. 2B). There was no noticeable collateral vein, so we waited until completion of the donor hepatectomy to prevent unnecessary splanchnic congestion.

Figure 2. Intraoperative photographs of dissection of the retrohepatic inferior vena cava and hepatoduodenal ligament dissection. The enlarged inferior hepatic vein was identified and encircled (arrow) (A), and the hepatic arteries were enlarged (B). After transection of the hepatic arteries, the portal vein was traced via hepatic parenchymal transection (C, D).

After transection of the hepatic arteries, the portal vein was traced via hepatic parenchymal transection (Fig. 2C, D). The right and left portal vein branches were clamped, leaving the PCS patent (Fig. 3A, B). After the recipient’s native liver was removed, the supra- and infra-hepatic IVC portions were clamped. At this time, the communicating inferior right hepatic vein was clamped and ligated to minimize the portal clamping time as much as possible owing to the absence of collateral veins (Fig. 3C, D). The right and left portal vein stumps were then opened to make a branch patch (Fig. 4A).

Figure 3. Intraoperative photographs showing removal of the recipient’s native liver. The right and left portal vein branches were clamped, leaving the portocaval shunt (arrow) patent (A, B). After the recipient’s native liver was removed, the supra- and infra-hepatic inferior vena cava portions were clamped (C). The communicating inferior right hepatic vein was also clamped and ligated (D).

Figure 4. Intraoperative photographs of graft implantation. The right and left portal vein stumps were opened to create a branch patch (A). The graft hepatic vein orifice of the left liver graft was enlarged by unification venoplasty of the left and middle hepatic vein openings (B). After the native liver was removed, the three hepatic vein orifices at the recipient inferior vena cava were unified (C). The graft hepatic vein was then reconstructed by continuous suturing with 5-0 polydioxanone (D).

A left liver graft measuring 335 g at the back table was recovered from the patient’s mother, yielding a graft-to-recipient weight ratio of 2.4%. The graft hepatic vein orifice was enlarged by unification venoplasty of the left and middle hepatic vein openings (Fig. 4B). After the native liver was removed, the three hepatic vein orifices at the recipient IVC were unified (Fig. 4C). The graft hepatic vein was then reconstructed by continuous suturing with 5-0 polydioxanone (Fig. 4D, 5A). The recipient portal vein branch patch was anastomosed with the graft portal vein using 6-0 polydioxanone suture (Fig. 5B, C). Thereafter, graft reperfusion was initiated, which showed normal reperfusion status (Fig. 5D). Surgical microscopy was used to reconstruct the graft left and middle hepatic arteries; Roux-en-Y hepaticojejunostomy was used for biliary reconstruction.

Figure 5. Intraoperative photographs of graft implantation. The graft hepatic vein was reconstructed by continuous suturing with 5-0 polydioxanone (A). The recipient portal vein branch patch was anastomosed with the graft portal vein using 6-0 polydioxanone suture (B, C). After graft reperfusion, the reperfusion status appeared normal (D).

The pathology report of the explant liver showed prominent thin-walled channels and arteriobiliary dyads in the portal tracts. Portal and focal septal fibrosis suggestive of congenital portosystemic shunt (Abernethy malformation) were observed (Fig. 6). The patient recovered from LDLT, and the reconstructed portal vein was maintained well without hemodynamic abnormalities (Fig. 7). At present, the patient has been doing well for 2 months after the LDLT.

Figure 6. Gross photographs of the explant liver.

Figure 7. Posttransplant computed tomography scan obtained at 5 days (A) and 2 weeks (B) after transplantation. The graft portal vein was perfused well without noticeable stenosis.

CAPV is a rare venous malformation in which the mesenteric venous blood drains directly into the systemic circulation. There are two types of congenital PCSs: intrahepatic and extrahepatic PCSs. Intrahepatic PCS is localized between the portal and hepatic veins or retrohepatic IVC [6]. Extrahepatic PCS can be divided into type I and type II based on intrahepatic portal venous supply [7]. Type I PCS is an extrahepatic shunt without a patent intrahepatic portal vein; thus, the entire mesenteric venous blood drains directly into the systemic veins, such as the IVC and left renal vein. Type II PCS is an extrahepatic shunt with a patent intrahepatic portal vein; thus, the patent portal vein perfuses the liver, and the shunt vessel drains some mesenteric venous blood into the systemic circulation. In the present case, our patient had intrahepatic PCS.

A standard treatment has not been established for CAPV probably because of the diverse features of CAPV and PCS. PCS is often accompanied by hyperammonemia, and the patients frequently show slightly abnormal liver function test results. The majority of patients with CAPV receive conservative medical treatment for hyperammonemia. However, a certain number of patients have been reported to have undergone surgical treatments, including LT. Surgical treatment is available for patients with hyperammonemia or portosystemic encephalopathy that is refractory to medical treatment. CAPV may also be accompanied by hepatopulmonary syndrome, which is an indication for LT [8,9].

In most cases, pretransplant imaging studies in CAPV patients reveal a large communication vein to the IVC through the splenorenal shunt or PCS. This status of the splanchnic blood flow system prevents development of portal hypertension. However, we previously reported an atypical case of CAPV showing portal hypertension with gastric and esophageal varix, which was the primary indication for DDLT [10]. In another case where the patient underwent LDLT for CAPV, no portal hypertension and collaterals were observed [11]. Meanwhile, another recent case showed noticeable portal hypertension with formation of esophageal and gastric varix, combined with marked splenomegaly and overt development of the splenorenal shunts [12].

In the present case, the extrahepatic portal vein was well developed such that the PCS was directly anastomosed with the graft portal vein in an end-to-end manner [2,13]. There was no development of the collateral veins, so intraoperative portogram was not performed. If there is evidence of portal hypertension with collateral formation, intraoperative portography is indicated because it is useful for identifying and embolizing the residual portosystemic collateral veins in young pediatric patients undergoing LT [14].

In conclusion, the features of CAPV and PCS are diverse in CAPV patients, so the portal vein reconstruction should be customized according to anatomical variations.

There was no funding related to this study.

All authors have no conflicts of interest to declare.

Conceptualization: JMN, S Hwang, SHO. Data curation: JMN, S Hwang, GCP, SHO. Formal analysis: S Hwang, S Ha, SG, JP, SHO. Investigation: All. Methodology: JMN, S Hwnag, GCP. Supervision: S Hwang. Validation: S Hwang. Visualization: S Hwang. Writing – original draft: JMN, S Hwang. Writing – review & editing: All.