Soapsuds enema (SSE)

A soapsuds enema (SSE) is a type of large-volume, evacuant enema administered to induce a bowel movement. It consists of a solution of water and a small amount of soap, which is introduced into the colon via the rectum. The primary function of an SSE is to treat severe constipation or fecal impaction and historically, to cleanse the bowel before a medical or surgical procedure.

Once a common procedure in hospitals and home care, the use of soapsuds enemas has significantly declined due to the availability of safer, more standardized alternatives and a greater understanding of its potential risks, most notably damage to the colonic mucosa.

Mechanism of Action

The soapsuds enema works through a dual-action mechanism:

1. Volume Distention: Like a tap-water or saline enema, the large volume of fluid (typically 1,000 to 1,500 mL or roughly 2 pints for an adult) distends the colon. This stretching of the intestinal wall triggers stretch receptors, which in turn stimulates peristalsis—the wave-like muscle contractions that propel feces through the bowel.
2. Chemical Irritation: The key component that differentiates an SSE is the soap itself. The soap acts as a chemical irritant to the mucous membrane (mucosa) lining the colon. This irritation further provokes and intensifies the peristaltic waves, leading to a more forceful evacuation than what would be achieved by water alone.

Procedure and Composition

A soapsuds enema is prepared by dissolving a small quantity of a mild, non-detergent soap into warm water.

• Solution: The solution typically consists of 3-5 mL (about one teaspoon) of a pure, mild soap per 1,000 mL of water.
• Type of Soap: The traditionally specified soap is a "soft soap," with Castile soap being the most common and recommended type. Castile soap is an oil-based soap, unlike harsh modern detergents. The use of household detergents, dish soaps, or antibacterial soaps is strictly contraindicated as they are much more caustic and can cause severe damage to the colon.
• Temperature: The water is heated to approximately 100-105°F (38-40.5°C) to be close to body temperature, which helps prevent cramping and discomfort.
• Administration: The solution is administered using an enema bag and tubing, with the patient typically lying on their left side in the Sims' position. The fluid is instilled slowly by gravity to allow for maximum distribution within the colon before evacuation is attempted.

Risks and Complications

While often effective, soapsuds enemas carry significant risks that have led to their decline in modern medical practice.

• Abdominal Cramping and Pain: The powerful stimulation of peristalsis can cause intense cramping, which is the most common side effect.
• Rectal Mucosa Damage: The irritant nature of soap can physically damage the delicate lining of the colon and rectum. Studies have shown that SSEs can cause loss of surface epithelium.
• Chemical Colitis: A serious complication is chemical colitis, an inflammation of the colon caused by exposure to harsh chemicals. Using the wrong type of soap (e.g., detergents instead of pure castile soap) or too high a concentration of soap can lead to severe inflammation, ulceration, bleeding, and in rare cases, perforation of the bowel.
• Electrolyte Imbalance: The administration of a large volume of a hypotonic solution (plain water) can lead to fluid and electrolyte disturbances, particularly if repeated. The body may absorb excess water, leading to a dilution of blood electrolytes, a condition known as water intoxication or hyponatremia. This is especially dangerous in children and frail elderly patients.
• Rectal Burns: If the water used is too hot, it can cause thermal injury to the rectum and colon.
• Infection: Improperly cleaned equipment can introduce harmful bacteria into the bowel.

Contraindications

Soapsuds enemas should not be used in patients with:

• Known inflammatory bowel disease (ulcerative colitis, Crohn's disease)
• Intestinal obstruction or perforation
• Recent colon or rectal surgery
• Severe dehydration or known electrolyte abnormalities
• Unexplained abdominal pain, nausea, or vomiting

Decline in Use and Modern Alternatives

The use of soapsuds enemas is now largely considered outdated and has been replaced by safer and more predictable methods for managing constipation and for bowel preparation.

Modern alternatives include:

• Oral Laxatives:
  • Bulk-forming agents: (e.g., psyllium, methylcellulose) increase the water content and bulk of the stool, making it easier to pass.
  • Osmotic laxatives: (e.g., polyethylene glycol 3350, lactulose, magnesium citrate) draw water into the colon to soften stool and stimulate bowel movements.
  • Stimulant laxatives: (e.g., bisacodyl, senna) act on the intestinal wall to increase motility. They are generally recommended for short-term use.
• Rectal Suppositories:
  • Glycerin suppositories: Act as a hyperosmotic laxative, drawing water into the rectum.
  • Bisacodyl suppositories: Provide direct stimulant action on the rectum.
• Other Types of Enemas:
  • Sodium Phosphate (Fleet) Enemas: Small-volume, hypertonic solutions that draw water into the colon. They are effective but must be used with caution, especially in the elderly and those with kidney or heart problems, due to the risk of phosphate toxicity.
  • Mineral Oil Enemas: Small-volume, lubricant enemas that coat the stool, allowing it to pass more easily.
  • Saline or Tap-Water Enemas: Rely solely on volume distention and are considered gentler than SSEs, though the risk of water intoxication with large-volume tap-water enemas remains.