Coronal reformatted images from portal venous phase post-iodinated contrast CT scan. A large volume of tumour has invaded the SMV and occupies the lumen of the main SMV trunk (ii). This impairs splanchnic blood flow to the liver resulting in pre-hepatic mesenteric venous hypertension and the formation of mesenteric varices (iv). The small bowel varices are responsible for the clinical presentation of GI haemorrhage. i SMV. ii Tumour invading SMV. iii Superior mesenteric artery. iv Large varices in the small bowel and left upper quadrant. SMV, superior mesenteric vein.