Managing Diarrhea After Rectal Adenocarcinoma Surgery

Following rectal cancer surgery, many patients experience an increase in bowel movements or episodes of diarrhea. Symptoms may include abdominal pain, watery stools with mucus, and a persistent feeling of urgency or incomplete evacuation. While bloody mucus is uncommon, these gastrointestinal disturbances can significantly affect quality of life. Several key factors contribute to postoperative diarrhea:

Changes in Bowel Anatomy and Function

One of the primary causes is the anatomical and functional changes that occur after surgery. The removal of part of the rectum reduces the surface area available for water absorption and diminishes the rectum's capacity to store stool. This often results in frequent, loose bowel movements, sometimes described as a "transit-time" effect. In most cases, the body gradually adapts over 2–3 months. If the stool remains well-formed despite increased frequency, symptoms often improve without intervention.

Autonomic Nervous System Disruption

Surgical removal of the tumor can also affect the autonomic nerves that control bowel function. This disruption may lead to symptoms such as cramping and diarrhea. Recovery is typically gradual, with the body compensating for these changes over time. In some cases, temporary medication or dietary adjustments may be needed to manage discomfort.

Imbalance in Gut Microbiota

Antibiotic use during the perioperative period, combined with surgical stress, can disturb the natural balance of gut bacteria. This imbalance—known as dysbiosis—can lead to persistent diarrhea, especially in older or immunocompromised patients. Probiotics or specific antimicrobial therapies may be recommended to restore intestinal flora and alleviate symptoms.

Chemotherapy-Induced Diarrhea

Patients undergoing adjuvant chemotherapy may experience diarrhea as a side effect. Chemotherapy drugs can irritate the intestinal lining, leading to increased bowel movements. Fortunately, this type of diarrhea usually improves once treatment is completed and the body clears the medication.

Dietary Considerations

Certain foods can exacerbate post-surgery digestive issues. High-fat broths, cold fruits, dairy products, and lactose-containing items are common triggers. Adjusting the diet to include bland, low-fat, and easily digestible foods often helps manage symptoms. Keeping a food diary can assist in identifying personal triggers and making informed dietary choices.