Enema

An enema, also known as a clyster, is the rectal administration of a fluid by injection into the lower bowel via the anus. The word enema can also refer to the liquid injected, as well as to a device for administering such an injection.
In standard medicine, the most frequent uses of enemas are to relieve constipation and for bowel cleansing before a medical examination or procedure; also, they are employed as a lower gastrointestinal series, to treat traveler's diarrhea, as a vehicle for the administration of food, water or medicine, as a stimulant to the general system, as a local application and, more rarely, as a means of reducing body temperature, as treatment for encopresis, and as a form of rehydration therapy in patients for whom intravenous therapy is not applicable.

Medical usage

The principal medical usages of enemas are:

Bowel cleansing

Acute treatments

As bowel stimulants, enemas are employed for the same purposes as orally administered laxatives: to relieve constipation; to treat fecal impaction; to empty the colon before a medical procedure such as a colonoscopy. When oral laxatives are not indicated or sufficiently effective, enemas may be a sensible and necessary measure.
A large volume enema can be given to cleanse as much of the colon as possible of feces. However, a low enema is generally useful only for stool in the rectum, not in the intestinal tract.
Such enemas' mechanism consists of the volume of the liquid causing a rapid expansion of the intestinal tract in conjunction with, in the case of certain solutions, irritation of the intestinal mucosa which stimulates peristalsis and lubricates the stool to encourage a bowel movement. An enema's efficacy depends on several factors including the volume injected and the temperature and the contents of the infusion. For the enema to be effective, the patient should retain the solution for five to ten minutes, as tolerated. or, as some nursing textbooks recommend, for five to fifteen minutes or as long as possible.

Large volume enemas

For emptying the entire colon as much as feasible deeper and higher enemas are utilized to reach large colon sections. The colon dilates and expands when a large volume of liquid is injected into it. The colon reacts to that sudden expansion with general contractions, peristalsis, propelling its contents toward the rectum.
Soapsuds enema is a frequently used synonym for a large volume enema.
A large volume enema may be used in a home setting to relieve occasional constipation, although medical care may be required for recurring or severe cases of constipation.

Water-based solutions

Plain water can be used, functioning mechanically to expand the colon, thus prompting evacuation.
Normal saline is least irritating to the colon. Like plain water, it simply functions mechanically to expand the colon, but having a neutral concentration gradient, it neither draws electrolytes from the body, as happens with plain water, nor draws water into the colon, as occurs with phosphates. Thus, a salt water solution can be used when a longer retention period is desired, such as to soften an impaction.
Castile soap is commonly added because its irritation of the colon's lining increases the defecation urgency. However, liquid handsoaps and detergents should not be used.
Glycerol is a specific bowel mucosa irritant serving to induce peristalsis via a hyperosmotic effect. It is used in a dilute solution, e.g., 5%.

Micro-enemas

ATC codes for drugs for constipation — enemas

Single substance solutions

In alphabetical order

Arachis oil enema is useful for softening stools which are impacted higher than the rectum.
Bisacodyl stimulates enteric nerves to cause colonic contractions.
Dantron is a stimulant drug and stool softener used alone or in combinations in enemas. Considered to be a carcinogen its use is limited, e.g., restricted in the UK to patients who already have a diagnosis of terminal cancer and not used at all in the USA.
Docusate
Glycerol has a hyperosmotic effect and can be used as a small-volume enema.
Mineral oil is used as a lubricant because most of the ingested material is excreted in the stool rather than absorbed by the body.
Sodium phosphate. Also known by the brand name Fleet. Available at drugstores; usually self-administered. Buffered sodium phosphate solution draws additional water from the bloodstream into the colon to increase the effectiveness of the enema. But it can irritate the colon, causing intense cramping or "griping." Fleet enemas usually cause a bowel movement in 1 to 5 minutes. Known adverse effects.
Sorbitol pulls water into the large intestines, causing distention, stimulating the bowels' normal forward movement. Sorbitol is found in some dried fruits and may contribute to the laxative effects of prunes. and is available for taking orally as a laxative. As an enema for constipation, the recommended adult dose is 120 mL of 25-30% solution, administered once. Note that Sorbitol is an ingredient of the MICROLAX Enema.
Compounded from multiple ingredients

In alphabetical order of the original brand names
Klyx contains docusate sodium 1 mg/mL and sorbitol solution 357 mg/mL and is used for faecal impaction or constipation or colon evacuation prior medical procedures, developed by Ferring B.V.
Micralax
MICROLAX® combines the action of sodium citrate, a peptidising agent which can displace bound water present in the faeces, with sodium alkyl sulphoacetate, a wetting agent, and with glycerol, an anal mucosa irritant and hyperosmotic. However, also sold under the name "Micralax", is a preparation containing sorbitol rather than glycerol; which was initially tested in preparation for sigmoidoscopy.
Micolette Micro-enema® contains 45 mg sodium lauryl sulphoacetate, 450 mg per 5 ml sodium citrate BP, and 625 mg glycerol BP and is a small volume stimulant enema suitable where large-volume enemas are contra-indicated.

Chronic treatments

Transanal irrigation

TAI, also termed retrograde irrigation, is designed to assist evacuation using a water enema as a treatment for persons with bowel dysfunction, including fecal incontinence or constipation, especially obstructed defecation. By regularly emptying the bowel using transanal irrigation, controlled bowel function is often re-established to a high degree, thus enabling a consistent bowel routine development. Its effectiveness varies considerably, some individuals experiencing complete control of incontinence but others reporting little or no benefit.
An international consensus on when and how to use transanal irrigation for people with bowel problems was published in 2013, offering practitioners a clear, comprehensive and straightforward guide to practice for the emerging therapeutic area of transanal irrigation.
The term retrograde irrigation distinguishes this procedure from the Malone antegrade continence enema, where irrigation fluid is introduced into the colon proximal to the anus via a surgically created irrigation port.

Bowel management

Patients who have a bowel disability, a medical condition which impairs control of defecation, e.g., fecal incontinence or constipation, can use bowel management techniques to choose a predictable time and place to evacuate. Without bowel management, such persons might either suffer from the feeling of not getting relief or soil themselves.
While simple techniques might include a controlled diet and establishing a toilet routine, a daily enema can be taken to empty the colon, thus preventing unwanted and uncontrolled bowel movements that day.

Contrast (X-ray)

In a lower gastrointestinal series an enema that may contain barium sulfate powder or a water-soluble contrast agent is used in the radiological imaging of the bowel. Called a barium enema, such enemas are sometimes the only practical way to view the colon relatively safely.
Failure to expel all of the barium may cause constipation or possible impaction and a patient who has no bowel movement for more than two days or is unable to pass gas rectally should promptly inform a physician and may require an enema or laxative.

Medication administration

The administration of substances into the bloodstream. This may be done in situations where it is undesirable or impossible to deliver a medication by mouth, such as antiemetics given to reduce nausea. Additionally, several anti-angiogenic agents, which work better without digestion, can be safely administered via a gentle enema.
Topical administration of medications into the rectum, such as corticosteroids and mesalazine, is used in the treatment of inflammatory bowel disease. Administration by enema avoids having the medication pass through the entire gastrointestinal tract, therefore simplifying the delivery of the medication to the affected area and limiting the amount that is absorbed into the bloodstream.
Rectal corticosteroid enemas are sometimes used to treat mild or moderate ulcerative colitis. They may also be used along with systemic corticosteroids or other medicines to treat severe disease or mild to moderate disease that has spread too far to be effectively treated by medicine inserted into the rectum alone.