S5552 Rectal Bypass to Disaster: A Rare SPSS Revealed on Repeat Imaging

Introduction: Spontaneous portosystemic shunts (SPSS) are collateral vascular connections that divert portal blood away from the liver in response to portal hypertension. While splenorenal and gastrorenal shunts are commonly encountered, porto-rectal shunts are exceedingly rare and poorly characterized in the literature. We present a case of decompensated cirrhosis with dual pathology: upper gastrointestinal bleeding from a Dieulafoy lesion and refractory hepatic encephalopathy caused by a SPSS in a rare location (Porto-rectal). Case Description/Methods: A 42-year-old man with decompensated cirrhosis secondary to chronic alcohol use presented to us with altered mental status, large-volume hematochezia, and features of decompensated cirrhosis. Initial labs revealed severe anemia, elevated creatinine, lactic acidosis, and hyperammonemia. Despite identifying and treating a rare dieulafoy lesion in endoscopy, controlling infection and adequate volume resuscitation, the patient’s ammonia levels remained high, and he continued to exhibit stage IV encephalopathy. Given the clinical suspicion of an occult SPSS, we performed contrast-enhanced computed tomography (CT) imaging. Common shunts, such as splenorenal or gastrorenal, were not seen. Just when we thought we had ruled out every cause, only a repeat computed tomography (CT) scan revealed an SPSS in exceedingly rare location -in between portal vein and rectal vein. Targeted embolization of this shunt, even though it exacerbates other complications of portal hypertension, including worsening ascites or development of other varices, is the best chance we saw in improving his mental status. It led to a dramatic improvement in his mental status and successful extubation. Unfortunately, despite a high Model for End-Stage Liver Disease score, the patient was not a candidate for liver transplantation due to ongoing alcohol use and poor socioeconomic support and ultimately succumbed to complications of end-stage liver disease. Discussion: This case highlights the diagnostic challenge posed by SPSS in an unanticipated location like Porto-rectal shunt that is often missed on initial imaging. It also emphasizes the importance of repeat advanced imaging in revealing hidden culprit when initial workup fails to explain persistent encephalopathy. Recognizing and treating these hidden shunts can dramatically reverse the life-threatening neurocognitive decline in cirrhotic patients.