Paradoxical diarrhea, also known as overflow diarrhea, arises from severe, long-term constipation rather than an infection. It occurs when a mass of dry, hardened stool, called a fecal impaction, becomes lodged in the lower colon or rectum. This blockage prevents the normal passage of feces, creating a severe obstruction. Treatment aims to safely clear this blockage.
What Causes Paradoxical Diarrhea
The core mechanism behind paradoxical diarrhea is the physical obstruction created by a fecal impaction, typically forming in the rectum or sigmoid colon. When this hard mass cannot be moved, the colon continues to process new waste material and absorb water, but the blockage remains in place. Above the impaction, new stool remains liquid or semi-solid as it cannot pass through the solidified mass.
The pressure of this accumulating liquid waste eventually builds up enough force to bypass the obstruction. This watery material seeps around the edges of the hardened fecal mass and leaks out of the anus. This leakage is mistakenly identified as diarrhea, but it is actually a sign of severe constipation and blockage.
Chronic constipation is the primary precursor to this condition, often resulting from low dietary fiber intake, inadequate fluid consumption, or limited physical mobility. Certain medications, especially opioid pain relievers, anticholinergic agents, and some iron supplements, significantly slow down gut motility and increase the risk.
Resolving Fecal Impaction
Treatment focuses on safely removing the impacted mass. Oral osmotic laxatives, such as polyethylene glycol, are often the initial step if the impaction is higher in the colon and a complete obstruction is not suspected. These agents draw water into the bowel to soften the mass, making it easier to pass over several days. Stimulant laxatives like bisacodyl should be used with caution, as they can cause painful cramping behind the obstruction.
Rectal Methods
If the impaction is lower in the rectum, suppositories and enemas are typically employed to target the mass directly. Glycerin suppositories pull fluid into the rectum to soften the stool and stimulate a bowel movement quickly. Medicated enemas, such as oil retention or sodium phosphate solutions, are inserted to soften the stool and lubricate the rectal wall.
Manual Disimpaction
In cases where these methods fail to clear the blockage, or if the impaction is particularly large or firm, manual disimpaction by a healthcare professional may be necessary. This procedure involves a lubricated, gloved finger gently fragmenting and removing the mass directly from the rectum. This technique is performed to prevent complications like stercoral ulceration.
Medical attention is necessary if severe symptoms develop, such as intense abdominal pain, fever, vomiting, or rectal bleeding. These signs can indicate a more serious complication, including bowel perforation or a complete bowel obstruction.
Preventing Recurrence
Establishing a long-term bowel management program is essential to prevent future episodes once the impaction is cleared. Increasing dietary fiber intake to the recommended 25 to 30 grams per day is foundational, using sources like whole grains, fruits, and vegetables. Fiber helps add bulk and water content to the stool, making it softer and easier to pass.
Adequate hydration is important, as fiber needs sufficient fluid to work effectively and prevent the stool from hardening again. Aiming for at least six to eight glasses of water daily helps maintain a soft stool consistency. Regular physical activity stimulates the muscles of the colon, promoting natural intestinal contractions that move waste along.
Developing healthy toileting habits is a key preventative measure, including not ignoring the urge to defecate and allowing sufficient time for a bowel movement. For individuals at high risk, a physician may recommend a maintenance regimen. This often includes regular use of bulk-forming agents like psyllium or stool softeners like docusate to ensure consistent bowel movements.