Congenital Intrahepatic Arterioportal Fistula: Extremely Rare Cause of Melena and Chronic Diarrhea in Children.

Congenital intrahepatic arterioportal fistulas are rare causes of presinusoidal portal hypertension in children. A rare case of arterioportal fistula in an infant is being reported. This report also highlights the need for long-term surveillance in such cases, despite being a benign pathology. Copyright:

INTRODUCTION

Congenital intrahepatic arterioportal fistula is a rare clinical entity in children. Till 2015, only 35 cases were reported in the literature.[1] Apart from clinical manifestations of early onset portal hypertension, chronic diarrhea and malnutrition due to intestinal dysfunction are quite common. Due to diarrhea and failure to thrive, symptoms of portal hypertension can be masked and these cases often pose as a diagnostic challenge. Ultrasound Doppler, when performed by an experienced radiologist, can easily detect abnormal arterioportal communication and features of presinusoidal portal hypertension. Selective embolization is the treatment modality of choice and surgical options are reserved for refractory cases. Herein, we describe a case of arterioportal fistula in an infant to highlight the rare clinical presentation and the importance of long-term surveillance.

CASE REPORT

An 11-month-old male infant, who was born at term weighing 2850 g after an unremarkable pregnancy, presented to our outpatient department with recurrent episodes of fresh bleeding per rectum for the past 2 months. The bleeding was episodic, 10–12 teaspoons/day and required blood transfusion. There was associated history of chronic diarrhea for which the child was evaluated elsewhere and was prescribed formula feeds and oral rehydration solution. There was no history of jaundice, hematemesis, vomiting, fever, inconsolable cry, or protrusion of mass per rectum.

On examination, the child was malnourished and had gross pallor with no icterus. His vitals were stable and systemic examination revealed mild splenomegaly with a span of 5 cm along its axis. On auscultation, no bruit was heard over the liver or enlarged spleen. Local examination revealed no fissure, rectal polyp, or prolapse. Liver function tests and prothrombin time were normal. Ultrasonography of the abdomen, which was done elsewhere, revealed splenomegaly and a dilated portal vein. Subsequently, a contrast-enhanced computed tomography (CECT) scan of the abdomen [Figure 1a] confirmed the above findings with the presence of an arterioportal fistula between the left hepatic artery and left branch of portal vein. An accessory left hepatic artery was also seen arising from left gastric artery. Liver parenchyma showed normal attenuation and enhancement and there was no ascites.

Figure 1

(a and b) Thin maximum intensity projection of computed tomography image (a) in coronal plane before embolization showing dilated left hepatic artery (thin arrow) opening in to a dilated left branch of portal vein (thick arrow) suggestive of congenital hepatic arterioportal fistula. (b) Thin maximum intensity projection of computed tomography image in coronal plane after embolization showing the vascular plug (outlined arrow) in the region of fistula. Also, the caliber of portal vein has significantly reduced

The child underwent CT-angiography and selective embolization of the fistula [Video 1] after initial optimization. Vascular access was achieved via trans-arterial route from right femoral artery. During the procedure, the main trunk of left hepatic artery and left branch of portal vein were communicating through a very short arterioportal fistula. Vascular plug (amplatzer© COOK MEDICAL) was used for embolization of the fistula. Post embolization, he had an uneventful recovery and was discharged after 48 h. At the time of discharge, the CECT and liver function tests were normal. Follow-up CECT scan [Figure 1b performed at 6 months was unremarkable without out any recurrence/persistence of the fistula with normal enhancement of the liver. After 1 year of follow-up, the child is asymptomatic and achieving milestones according to his age.

DISCUSSION

Congenital intrahepatic vascular shunts can occur between portal vein and hepatic artery (arterioportal), portal vein and hepatic vein (porto-systemic venous) and hepatic artery and hepatic vein (arteriosystemic venous). Rarely, systemic venous (hepatic vein to hepatic vein) and portoportal communications are also seen.[2] Arterioportal shunts or fistulas can be acquired or congenital. Acquired shunts occur in patients with cirrhosis, hepatic neoplasms, penetrating trauma, percutaneous liver biopsy, biliary surgery, etc., Congenital arterioportal shunting is less common. It can be idiopathic or associated with syndromes such as Osler–Weber–Rendu (hereditary hemorrhagic telangiectasia) or Ehlers–Danlos syndrome.[23] At times, an intrahepatic arterioportal fistula can be difficult to differentiate from other intrahepatic causes of portal hypertension, for example, Cruveilhier-Baumgarten syndrome. An absence of caput medusae and venous hum on clinical examination and paucity of a giant paraumbilical vein on CECT and CT angiography points to a likelihood of an arterioportal fistula rather than Cruveilhier–Baumgarten syndrome.[4]

Children with congenital fistulas can present at any age but most of them present within infancy. Clinical features of portal hypertension such as splenomegaly (with hypersplenism), upper gastrointestinal bleeding (hematemesis or melena), ascites, etc., are common. In the index case, bleeding per rectum likely occurred due to esophageal/gastric varices. Although symptoms and signs of portal hypertension develop quite early in these cases, liver function remains normal in all cases.[35] Quite interestingly, half of the cases with congenital fistulas present with chronic diarrhea and failure to thrive. Hepatofugal blood flow causes venous congestion and stasis in portal and superior mesenteric veins leading to portal-hypertensive enteropathy (PHE) and intestinal dysfunction. Chronic diarrhea in the present case can also attributed to PHE. Protein losing enteropathy and fat malabsorption can occur in around 20% of cases.[56] Chronic diarrhea is so common that it can even precede the signs and symptoms of portal hypertension.[5] In developing countries like ours, this can mask other clinical features and diagnosis is often delayed.

Radiological investigations such as ultrasound Doppler, CECT, and contrast-enhanced magnetic resonance (MR) are useful investigations in diagnosis of these fistulas. Ultrasound Doppler usually reveals dilatation of portal vein where fistula is located and pulsatile hepatofugal flow in portal vein.[3] CECT usually demonstrates marked enhancement of portal vein and its branches with attenuation reaching that of aorta on arterial-phase images. Similar findings are seen on MR scan.[3] CT angiography need not to be performed for diagnosis and should be reserved for therapeutic embolization only.[3]

Treatment in these cases is aimed at obliteration of the fistula. Options include selective transarterial embolization (TAE), surgery or a combination of both. TAE is the treatment of choice and has shown fairly good success in cases with single feeder artery.[5] The success rate is around 40%–50% including all cases.[7] In the index case, the presence of an accessory left Hepatic artery from LGA was an anatomical advantage. Accessory arterial supply protects from hepatic arterial ischemia and further transient transaminitis due arising due to occlusion of the left hepatic artery by TAE. Endoscopic resolution of varices and congestive changes in the stomach and small bowel can be achieved within a week after embolization.[8] After a successful embolization, these children are usually followed up regularly because arterial collateralization and recurrence of fistula is not uncommon.[35] Surgical options should be reserved for complex cases with recurrence or multiple fistulas refractory to multiple sittings of TAEs. It includes procedures such as ligation of the fistula, hemi-hepatectomy or lobectomy, and end-to-side portocaval shunt. Hemihepatectomy poses a significant risk of mortality in these cases because of severe malnutrition and failure to thrive.[5] Liver transplantation should be considered for refractory cases or children who have developed hepatoportal sclerosis and fibrosis due to late presentation.[3]

CONCLUSION

Congenital arterioportal fistulas are rare causes of portal hypertension in children. Malnutrition and chronic diarrhea indicate intestinal dysfunction. Selective embolization is the treatment modality of choice. A long-term follow-up is necessary to rule out recurrences due to arterial collateralization.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.