The possibility of metastasis should be suspected when inguinal lymph nodes are touched 3 months after rectal cancer surgery, and relevant examinations should be further improved to clarify the diagnosis, such as ultrasound of lymph nodes, CT of chest and abdomen, tumor markers, PET-CT, etc. 1. Ultrasound of lymph nodes: Ultrasound can evaluate the condition of superficial lymph nodes, including lymph node enlargement, adhesion, number, relationship with surrounding structures, etc. It can help to detect lymph node abnormalities and assist in the diagnosis or exclude metastasis. 2. Chest and abdomen CT: when lymph node metastasis of rectal cancer is suspected, one should also be alert to tumor recurrence or distant metastasis, such as liver metastasis, lung metastasis, etc. Chest and abdomen CT can be performed to make a clear diagnosis. Abdominal CT can also observe whether the lymph nodes in the abdominal cavity are enlarged or not. 3. Tumor markers: most patients will have fluctuation of tumor markers, such as carcinoembryonic antigen, glycan antigen 199, etc., when rectal cancer metastasis or recurrence occurs after surgery. Tumor markers should be suspected of metastasis or recurrence if they are elevated for a period of time after surgery. 4. PET-CT: PET-CT is a kind of examination means to detect systemic metastasis of malignant tumors, but the price is relatively high, so patients with conditions can consider using it. If the inguinal lymph nodes are enlarged 3 months after rectal cancer surgery, it is suggested that patients should go to the hospital as soon as possible, consult with professional doctors, complete the corresponding examination as soon as possible, and make a clear diagnosis in time and then give targeted treatment.