An enema is a liquid administered via the rectal route either to aid bowel evacuation or to administer medication (Galbraith et al, 2013; Dougherty and Lister, 2015). This article will discuss the use of enemas for constipation in adult patients.
Indications
Indications for the use of enemas include to:
Contraindications
The use of enemas is contraindicated in patients with a paralytic ileus or chronic obstruction. It is also contraindicated where administration may cause circulatory overload, mucosal damage, necrosis, perforation, haemorrhage or following any gastrointestinal or gynaecological surgery where sutures may be ruptured (Dougherty and Lister, 2015).
Enemas for constipation
Most commonly, enemas are used to relieve and treat constipation. NICE (2017) defines constipation as a symptomatic disorder of unsatisfactory defaecation due to difficulty or infrequency of passing stools that is a change to the individual's normal bowel pattern. Chronic constipation is diagnosed when symptoms persist for at least 12 weeks in the past 6 months (NICE, 2017). Early assessment and treatment of constipation is necessary to prevent long-term implications such as faecal loading, impaction or retention, haemorrhoids, anal fissures, distension or loss of sensory and motor functions (NICE, 2017).
Types of enemas
There are various types of enemas used for constipation, which should only be prescribed following a full biological, psychological and sociological assessment of the patient (NICE, 2017). Enemas are licensed for occasional use only; the patient should always be reassessed following administration and the effects evaluated (Pegram et al, 2008; NICE, 2017). Administration of an enema must be performed by a practitioner with the appropriate knowledge and skills and within their scope of professional practice (Nursing and Midwifery Council (NMC), 2018). Nurses must be aware of any potential harm associated with enema administration, such as trauma to the anal mucosa, and must be accountable for their actions (NMC, 2018).
Evacuant enemas
Evacuant enemas are administered into the rectum or lower colon. The osmotic activity in the solution increases the water content in the stool, producing distension in the rectum that leads to stimulation of peristalsis and induces defaecation by stimulating rectal mobility (Dougherty and Lister, 2015; NICE, 2017). Phosphate enemas are evacuant enemas, classed as saline laxatives, and are useful for removing hard or impacted stools (NICE, 2017). They are available in single-dose, disposal packs with a standard or long rectal tube. A bowel evacuation should occur approximately 2-5 minutes after administration. Although phosphate enemas are often used to clear the bowel before an examination, X-ray or surgery, there is little evidence to support their use (Dougherty and Lister, 2015). Associated risks of phosphate absorption from the enema due to lack of evacuation include hypovolaemic shock, renal failure and oliguria (diminished capacity to form or pass urine) and rectal injury from the tip of an enema nozzle in an empty bowel (Dougherty and Lister, 2015). There is also a risk of rectal gangrene in patients who are systemically unwell and have a history of haemorrhoids (NICE, 2017). The use of phosphate enemas is contraindicated with patients who show signs of dehydration or renal impairment and it is important that good fluid intake is encouraged to prevent dehydration (NICE, 2017).
Sodium citrate enemas (also evacuant enemas) create the same osmotic activity in the bowel as phosphate enemas. They are smaller in volume and are also used for removing hard or impacted stools. Evacuation can take between 5 and 15 minutes following administration. Sodium citrate enemas should be used with caution in older people and in patients who are at risk of sodium and water retention (NICE, 2017). The adverse side effects of osmotic laxatives are cramps or abdominal pains, bloating, flatulence, nausea and vomiting.
Docusate sodium enemas, also used for chronic constipation, act as a stimulant laxative and faecal softener. Faecal softeners are thought to act by decreasing surface tension and increasing intestinal fluid penetration into faecal mass. Response to rectal administration generally occurs in 20 minutes.
Retention enemas
Retention enemas are introduced into the rectum with the intention of them being retained for a specific period of time. They work by increasing the bulk and softness of the faeces; however, there is limited evidence to support the use of these enemas in constipation (Woodward, 2012; Dougherty and Lister, 2015). Two types of retention enema are most commonly used: arachis oil enemas and prednisolone enemas. Prednisolone enemas are used for drug administration if oral medication is deemed unsuitable. Nurses must be aware of the contraindications for prednisolone enemas prior to administration. These include bowel perforation, intestinal obstruction, extensive fistulas and recent intestinal anastomoses (NICE, 2017). The arachis oil enema is indicated for patients with hard, impacted stools. It works as a softening agent and should be warmed before administration and retained overnight (NICE, 2017). Arachis oil enemas are contraindicated for patients with peanut allergies.
See Table 1 for a summary of enemas for use in constipation.
| Enema | Type | Use |
|---|---|---|
| Docusate sodium enema | Softener and weak stimulant evacuant enema | Can be used for hard stools. Caution must be taken to administer this enema correctly to avoid damage to the rectal mucosa |
| Sodium citrate enema | Osmotic evacuant enema | Useful in the removal of hard impacted stools. Occasional use only. Caution should be taken with administration to avoid damage to the rectal mucosa. Additional caution should be taken with older people and those at risk of water and sodium retention |
| Phosphate enema | Osmotic evacuant enema | Used for hard, impacted stools. Contraindicated in people who have signs of dehydration or renal impairment. For occasional use only |
| Arachis oil enema | Softener and retention enema | To be used overnight. Used for hard, impacted stools. Contraindicated in people who have a peanut allergy. For occasional use only |
Checks and assessments
All enemas must be prescribed and checked against the prescription before administration (Dougherty and Lister, 2015). It is important that the procedure is clearly explained and understood by the patient to ensure that informed consent is gained (NMC, 2018).
Administration of medications via the rectal route can be embarrassing for the patient; it is essential that nurses maintain privacy and dignity at all times. A moving- and-handling risk assessment should be completed before treatment to establish if additional equipment is required.
Equipment
Before administration of an enema, it is essential to correctly assemble all the necessary equipment. This should include:
Procedure
Summary
Administration of enemas is an invasive technique. Nurses need to carry out a full assessment of the patient prior to this procedure and only administer an enema if they have the appropriate knowledge and skills. Respect for the patient's privacy and dignity should be maintained at all times and a full reassessment must take place following the procedure.