Abernethy malformation (AM) is a rare congenital abnormality described by John Abernethy in 1793. It is characterized by a shunt between the portal vein and systemic circulation [1, 2]. It is frequently associated with other congenital abnormalities, including the absence of a portal vein and/or congenital mesenterico-caval shunt, cardiac and/or pulmonary malformation and liver nodules [3, 4]. Complications of Abernethy malformation include hepatic encephalopathy, hepatopulmonary syndrome, portopulmonary syndrome and hepatic tumors .
A meticulous assessment of the liver and vascular anatomy by non-interventional abdominal exams in Abernethy malformation aids diagnosis and planning of appropriate treatment. In this study, we detailed some important direct and indirect findings of non-invasive imaging methods and highlight the value of CT scans and Color Doppler Duplex Ultrasound for the diagnosis, treatment and evolution assessment of two adult patients with Abernethy malformation.
This study was approved by the Institutional Review Board fulfilling all requirements for studies in humans, following the guidelines of the 1975 Declaration of Helsinki.
AM is an extremely rare syndrome, with less than 20 cases reported in English language medical literature. Most patients with AM suffer premature mortality as a result of the serious conditions related to this syndrome. In those patients with mild conditions, the presence of a portocaval systemic shunt is often not recognized during childhood . This diagnosis was also not recognized in infancy for these cases, but with appropriate imaging exams, accurate diagnosis was made in adulthood. The majority of affected patients already described were below the age of 18 and female . Almost all reported cases were admitted to hospital with a variety of symptoms, including nausea, vomiting, fatigue, epigastric pain, asthenia, anorexia, jaundice and dyspnea .
The second case was initially presumed to be agenesis of the portal vein with decompensated hepatic dysfunction. However, after sagittal and coronal scans beyond the axial planes of the abdominal multidetector tomography, and detailed Doppler Duplex liver ultrasonography exams, the abnormal liver vascular anatomy was identified as AM. Occasionally, the image diagnosis is easy to make , but in this case, meticulous evaluation of the liver and vascular anatomy by non-interventional abdominal exams for Abernethy malformation with many plane sections improved the diagnosis.
Portal vein thrombosis exclusion is also a differential diagnosis of AM. Currently, cavernous transformation of chronic portal thrombosis can be identified with high accuracy using Doppler Duplex Ultrasonography exams and CT imaging . The diagnosis of Abernethy malformation from acquired causes of absent portal veins depends on delineating of the extrahepatic portal vein anatomy by radiological exams, intraoperatively, or at autopsy. In this study, accurate diagnosis was made using non-invasive imaging methods without radiation, when the Doppler Duplex could indicate the portocaval shunt abnormality, or by angio-TC that could clarify the vascular anatomy instead of more invasive angiography exams . In the first case the confirmation for diagnosis was achieved by the explant following liver transplantation.
The combination of both imaging methods, first US and than CT gives a better chance of detecting rare liver disease, considering also, a recently revision that suggests the US as the first line option to assess liver disease . We showed (Figs. 2, 3 and 4) images changes along many slices and multiples scan where we could suggest the presence of vascular anomalous path through the venous ligament as an important direct signal effect. On the other hand, the indirect effects can be related to absence of a trunk portal vein through the hepatic hilum and along the right and left portal branch way (2nd, 3rd and 4th branch portal ramification, usually visualized in the conventional imaging methods), as the enlarged and hypertrophied hepatic artery in the hepatic hilum.
The main advantages of US are that it is non-invasive, available in most health centers, and is not expensive . However, it is somewhat limited in its diagnostic accuracy by the fact that it depends heavily upon the opinion of the operator, and provides only a partial view of the anatomy in each scan. This makes it well suited to early identification or front line use, but diagnosis should be clarified with CT. The advantages of CT are that it is less subjective and provides a better panoramic view of the anatomy. However it is much more expensive and less commonly found in health centers, meaning that we recommend it as a reinforcement of the initial impression given by US.
The association of portal vein anomaly and nodular liver lesions was observed in almost half of the reported cases, and the most frequent lesion is the focal nodular hyperplasia . The treatment options for Abernethy malformation include surgical correction of shunts, liver nodule resection and liver transplantation . In these cases, the first one underwent liver transplantation and the second, was monitored by close clinical and imaging follow up.
In summary, we reported and detailed some important direct and indirect findings of non-invasive imaging methods. On two cases of AM in an attempt to evaluate the significance of CT angiography and Duplex Doppler liver plane anatomy to identify variations of liver anatomy and vascular malformations. These imaging methods are crucial to improve the clinical diagnosis of AM and to avoid iatrogenic procedures when planning liver surgery strategy.