Typically, it is between stomach and small bowel that is distal (or further down the gastrointestinal tract) from the cut end.

[1] The name is derived from the surgeon who first described it (César Roux)[1] and the stick-figure representation.

[citation needed] Typically, the two upper limbs of the Y represent (1) the proximal segment of stomach and the distal small bowel it joins with and (2) the blind end that is surgically divided off, and the lower part of the Y is formed by the distal small bowel beyond the anastomosis.

[1] When describing the surgery, the Roux limb is the efferent or antegrade limb that serves as the primary recipient of food after the surgery, while the hepatobiliary or afferent limb that anastomoses with the biliary system serves as the recipient for biliary secretions, which then travel through the excluded small bowel to the distal anastomosis at the mid jejunum to aid digestion.

Iron-deficiency anemia develops in up to 45% of people who have had a Roux-en-Y anastomosis.