There are several common reasons for anal swelling in the afternoon. The first one is that if the patient has long term constipation or constipation, it is usually manifested as fecal retention in the rectum, which can also lead to a feeling of anal swelling. Secondly, if the patient has constipation with outlet obstruction, such as anterior rectal protrusion, internal rectal overturning or mixed hemorrhoids, which manifests as anal swelling, anal discomfort, and sometimes anal blockage, rectal examination and fecal imaging can make a clear diagnosis. Thirdly, if a patient has a malignant rectal tumor, the lateral infiltration of the tumor along the rectal wall can sometimes lead to a feeling of anal swelling, and a hard mass can be palpated by rectal examination. Therefore, there are many causes of anal swelling, which should be combined with medical history, physical examination and auxiliary examinations to make a clear diagnosis.