What causes blood in stool after surgery for rectal cancer?

Nov 15, 2025 Source: Cainiu Health

Dr. Li Jingxiang

Introduction

In general, postoperative rectal bleeding after colorectal cancer surgery may be caused by oozing from the anastomotic site during healing, dietary irritation of the intestinal mucosa, intestinal flora imbalance, ulcerative colitis, or rectal polyps. It is recommended to seek medical attention promptly, identify the underlying cause, and receive symptomatic treatment under a doctor's guidance. Maintain regular bowel habits in daily life, avoid prolonged squatting and straining during defecation, and keep the perianal area clean.

In general, rectal bleeding after surgery for rectal cancer may be caused by factors such as oozing from the anastomotic site during healing, dietary irritation of the intestinal mucosa, intestinal dysbiosis, ulcerative colitis, or rectal polyps. It is recommended to seek timely medical attention, identify the underlying cause, and receive symptomatic treatment under a doctor's guidance. Specific analyses are as follows:

1. Bleeding during anastomotic healing: In the short term after surgery, the anastomosis has not fully healed, and minor bleeding may occur due to friction during bowel movements, with blood appearing on the surface of the stool. Initially after surgery, patients should consume soft, mushy, or liquid foods, avoid coarse foods, rest in bed as directed by their physician, and symptoms usually resolve spontaneously as healing progresses.

2. Dietary irritation of intestinal mucosa: After surgery, the intestinal mucosa is sensitive, and consumption of spicy or hard foods can irritate and damage the mucosa, leading to bleeding. Adjust the diet to include mild, easily digestible foods such as porridge and soft noodles, eat more steamed eggs and tofu, drink plenty of water to soften stools, and reduce mucosal irritation.

3. Intestinal dysbiosis: Imbalance of gut flora due to postoperative antibiotic use or intestinal dysfunction may lead to mucosal inflammation and bleeding. Follow medical advice to take medications such as Bifidobacterium triple viable capsules, Bacillus subtilis and Enterococcus faecalis viable granules, or Clostridium butyricum viable capsules to restore intestinal microbial balance.

4. Ulcerative colitis: Immune abnormalities in the intestine cause ulcers in the colonic mucosa, resulting in bleeding from the ulcerated areas during defecation, often accompanied by abdominal pain and diarrhea. Follow medical advice to use anti-inflammatory medications such as mesalamine enteric-coated tablets, sulfasalazine enteric-coated tablets, or olsalazine sodium capsules to control the inflammatory response.

5. Rectal polyps: Postoperative mucosal hyperplasia in the intestine may form polyps, and friction during bowel movements can cause surface erosion and bleeding. Endoscopic polypectomy is required to completely remove the polyps surgically, preventing recurrent bleeding and disease progression.

Maintain regular bowel habits in daily life and avoid prolonged straining or squatting during defecation. Keep the anal area clean and gently wash with warm water after bowel movements. Schedule regular follow-up colonoscopies to monitor intestinal recovery. Maintain emotional stability, avoid anxiety, and enhance the body’s healing capacity through regular作息 (daily routines).

View All

Can the anus be preserved during surgery for rectal cancer?

In general, whether the anus is preserved during surgery for rectal cancer mainly depends on the tumor's location, size, stage, and the patient's specific health condition. Patients who retain their anus should initially follow a liquid diet after surgery, gradually transitioning to soft foods, and consume more high-fiber foods to maintain regular bowel movements. Patients with a stoma need to regularly clean the stoma site, change the ostomy bag, and prevent local skin infections.

View Full Answer

How is early-stage rectal cancer surgically treated?

Surgical approaches for early-stage rectal cancer include endoscopic mucosal resection, endoscopic submucosal dissection, laparoscopic radical rectal resection, robot-assisted laparoscopic radical rectal resection, and open radical rectal resection, with the choice depending on factors such as tumor location and size. If symptoms such as rectal bleeding or abdominal pain occur, prompt medical evaluation is recommended to establish an accurate diagnosis.

View Full Answer

Is chemotherapy necessary for colon cancer?

In general, whether chemotherapy is needed for colorectal cancer should be determined based on a comprehensive evaluation of the patient's specific condition, cancer stage, physical status, and other factors. A thorough assessment of the disease and the patient's tolerance is required before deciding on chemotherapy; treatment should not be initiated blindly. During chemotherapy, it is important to maintain adequate nutrition, eat light and easily digestible meals, and reduce gastrointestinal burden.

View Full Answer

What are the medications for rectal cancer?

Medications for rectal cancer include chemotherapy drugs, targeted therapy drugs, immunotherapy drugs, anti-angiogenesis drugs, and symptomatic and supportive treatment drugs. Individualized treatment plans should be developed based on cancer stage and patient's physical condition. If adverse drug reactions or changes in condition occur, prompt medical attention is recommended. Commonly used drugs include oxaliplatin, capecitabine, and fluorouracil.