The needle is placed so that it gets a substantial bite of muscularis and the important submucosal layer, but only a small bite of the edge of the mucosa. As soon as the mucosa is cut it begins to become edematous. Including a large bit of mucosa in the stitch will make a bulky anastomosis which might be partially occluded. In addition, when the edema in a bulky bite of mucosa subsides, the stitch will loosen with the potential for leak.
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