What are the veins that come outside the rectum?

The veins that come outside the rectum primarily include the hemorrhoidal veins, which are divided into three main groups: the superior, middle, and inferior hemorrhoidal veins. The superior hemorrhoidal vein drains into the inferior mesenteric vein, while the middle and inferior hemorrhoidal veins drain into the internal and external iliac veins, respectively. These veins can become swollen or engorged, leading to conditions such as hemorrhoids.