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Pre-colonoscopy laxatives

Diagnostics> Colonoscopy

Dr. med. Another summer

The colonoscopy is an important examination method for the detection of intestinal diseases. It is also used to prevent colon cancer. It is crucial for the diagnosis that the intestinal mucosa is to be examined as well as possible. Therefore, patients must purgate before a colonoscopy. This makes the intestine as clean as possible and free of stool residues. How is purging carried out and what different purging methods are there?


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The most important things at a glance:

  • colon cleansing begins at least one day before the colonoscopy
  • Before the colonoscopy, the stool should be clear and fluid and about the color of chamomile tea
  • Every doctor's practice has its own standards for colon cleansing: the staff gives the patient an information sheet in advance and explains how to proceed
  • to discharge there Polyethylene glycol solutions (PEG solutions) and salt-based, so-called saline solutions: the remedies differ, among other things, in terms of mode of action and amount of drink
  • The colonoscopy is only meaningful if there are good "visual conditions" after a colon cleanse
  • Patients should no longer consume grains three days before the colonoscopy
  • in the absence of the laxative effect one should contact the doctor's office

Why do you have to do a purging before the colonoscopy?

Colon cleansing is for quality and The informative value of the colonoscopy very important. During a colonoscopy, the examiner inserts a tube with a small camera through the anus into the intestine. The intestinal mucosa is assessed using the enlarged image from the camera. The removal in advance serves to cleanse the intestinal mucosa.

If the removal before the mirroring does not succeed as required, the intestinal mucosa can only be examined to a limited extent, as possible changes are only poorly visible. The examination may have to be repeated in such cases.

Are there any further examinations before the colonoscopy?

A few days before the colonoscopy, the doctor will take blood from the patient to obtain the To determine coagulation values. It is important to keep the blood clotting properly, as injuries that may bleed may occur during the examination.

Minor interventions can also be carried out during the colonoscopy. If, for example, growths of the mucous membrane (so-called polyps) are discovered during the mirroring, these can be removed immediately. This can then lead to bleeding.

The examination of blood coagulation can usually be carried out by your family doctor. Anyone who takes blood thinners should definitely tell the doctor. Even if there are allergies such as latex or diabetes mellitus, you should address this in the consultation.

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What is the diet like before the colonoscopy?

The laxative usually starts the day before the examination. A few days before the examination, the preparation of the intestine begins in the form of a diet.

The person concerned should get up three to five days before the examination Avoid foods that contain grains. These include muesli, bread or rolls with grains, but also kiwis or figs, which contain grains in the edible portion of the fruit.

Two days before the colonoscopy, it can be helpful to drink a lot (at least two liters). Smaller, more frequent meals can also help with preparation.

In the morning and at noon on the day before the examination, you can only easily digestible food to take in. For example, porridge, yoghurt or clear broth are allowed. Affected people who are prone to constipation start earlier: a few days before the examination, these people should only consume easily digestible foods.

A sufficient one Hydration is very important for bowel preparation as fluids help the laxative work. You can drink whatever you want up to two days before the colonoscopy. From the day before the colonoscopy, only clear liquids are allowed. The reason for this is that dyes and tannins in some drinks such as coffee, black tea or cola can stain the intestinal mucous membranes. This can limit the informative value of the colonoscopy. Even while taking the laxative, those affected should continue to drink plenty of clear fluids.

If you take iron supplements, you should omit them four days before the colonoscopy.

What laxatives are there to prepare for a colonoscopy?

One distinguishes between Polyethylene glycol solutions (PEG solutions) and saline laxatives. PEG solutions contain roughly the same amount of salts as body fluids. The taste is therefore slightly salty.

Saline laxatives contain, for example, magnesium citrate or sodium phosphate. Compared to body fluids, they contain more salts (hyperosmolar). For this reason, they withdraw a lot of water from the body through the intestinal wall. This leads to the desired effect that the chair becomes voluminous and thin. Often agents are added that stimulate bowel movement. An example of this is sodium picosulfate. Saline laxatives only require a comparatively small amount of laxative: two times 150 milliliters are sufficient. In addition to the solution, patients should drink a total of at least two liters of clear fluids.

PEG supplements are dissolved in water and drunk. Usually it is two times a liter of water plus at least one liter of freely selectable clear liquids. Relatively large amounts of liquid are required. Due to their structure, PEG solutions attract water and thus make the stool liquid. At the same time they activate the intestinal motility, that is, they set the intestine in motion. The large amount of fluid and the movement cleanse the bowel. Since 2018 there has also been a new, PEG-based laxative called Plenvu. Here, only one liter of laxative plus one liter of clear liquid is required for the entire preparation.

What side effects can colon cleansing have?

Purging before the colonoscopy is not pleasant: those affected have to ingest large amounts of fluids and avoid solid food. This leads to diarrhea until only clear fluid is excreted. Nevertheless, purging before the colon cleansing is unfortunately inevitable and usually tolerable for those affected.

These side effects can occur:

  • Nausea and vomiting: The nausea can also be so severe that it is not possible for the person concerned to continue preparing for the colonoscopy.
  • Headache and stomach ache
  • Dehydration: The laxative measures lead to a high loss of water. For this reason, drinking a lot of fluids in addition to taking the laxatives is important. Elderly patients in particular may have difficulty compensating for fluid loss.
  • Electrolyte shifts: Saline laxatives, in particular, remove water from the body. This can lead to changes in the body's salt balance. This is also known as electrolyte shift. One example is hyponatremia, which is a lack of sodium in the blood. Possible symptoms are nausea, fever, confusion and headache. Hyponatremia can be dangerous and needs treatment.

What are the advantages and disadvantages of PEG and saline laxatives?

Colon cleansing with PEG and saline laxatives offers various advantages and disadvantages.

PEG-based laxatives (for example Moviprep):

  • Advantages:

    • better sight on the intestinal mucosa and thus better examination conditions
    • Electrolyte shifts kick in the patient's blood less common on and are less severe
  • Disadvantage:

    • Patients must more laxatives drink, this arises compared to saline agents more frequent nausea

Saline laxatives (for example picoprep)

  • Advantages:

    • the laxative is dissolved in less volume that Drinking quantities are smaller; thereby less nauseathan with PEG solutions
  • Disadvantage:

    • worse cleaning results than with PEG solutions
    • serious Side effects are more common (among other things electrolyte shifts)

When is colon cleansing successful?

Diarrhea sets in about one to three hours after taking the laxative. Before the colonoscopy, the stool should be taken clear, liquid and yellowishcomparable to the color of chamomile tea or urine. If this is not the case, the doctor must be informed.

What to do if the laxative doesn't work or if you vomit?

If the taste of the laxative makes you nauseous, it may help through a straw to drink. This means that fewer taste buds are irritated on the tongue. If you have the feeling that the laxative is not working properly, you should contact your doctor. This can then initiate additional laxative measures.

So far there is no alternative to dam cleaning. Every doctor's practice that does a colonoscopy has its own procedure for colon cleansing. The doctor often consults with the person concerned beforehand about which method is best suited to the individual situation.

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Dr. med. Another summer

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