In compression of the inferior mesenteric vein just before it joins the splenic vein, which of the following vein is most likely enlarged

In compression of the inferior mesenteric vein its tributaries like left colic vein gets enlarged - Venous drainage of Hind-Gut territory. Middle colic vein (option 1) is a tributary of superior mesenteric vein - Venous drainage of Mid-Gut territory. Left gastroepiploic (gastro-omental) vein (option 2) drains into splenic vein. Inferior pancreaticoduodenal vein (option 3) drains into supperior mesenteric vein- Venous drainage of Hind-Gut territory. *Poal vein is formed posterior to the neck of pancreas by the union of the splenic vein and superior mesenteric vein. The inferior mesenteric vein usually ends by joining the splenic vein.The blood within the poal vein carries high levels of nutrients from the GI tract and products of red blood cell destruction from the spleen.