Overview of Bowel Preparation
Doctors use a variety of strategies to prepare the bowel for a procedure called a colonoscopy. A colonoscopy is considered the best way to get a detailed look at the lining of the colon, helping doctors to spot any abnormal growths that may need to be removed or further examined. However, studies have shown that in about 10% to 20% of cases, doctors can’t fully examine the colon due to incomplete colonoscopies. This might occur if the bowel hasn’t been fully emptied before the procedure. If this happens, doctors might miss cancerous growths, and the procedure could have a higher chance of causing complications.
There are several known factors that could make it more difficult for patients to adequately prepare their bowels for a colonoscopy. These include having had issues with bowel preparation in the past, being a non-English speaker, having Medicaid coverage, being single, being hospitalized, taking multiple medications, being overweight, being elderly, being male, and having certain health conditions such as diabetes, stroke, dementia, and Parkinson’s disease.
The ideal bowel prep should make patients as comfortable as possible and avoid causing significant changes in fluid and electrolyte levels in the body. It should also be safe, easy to tolerate, and affordable.
Anatomy and Physiology of Bowel Preparation
Properly cleaning out your bowels before a colonoscopy can make it easier for the doctor to spot any problems. A colonoscopy is a type of medical exam where the doctor checks your rectum and colon, including all its sections and the end part of your small intestine called the terminal ileum.
Why do People Need Bowel Preparation
If you need a colonoscopy, it’s important to properly prepare your bowel beforehand. This usually involves eating a special diet and taking certain medications to clean out your colon, so the doctor can clearly see and examine your colon during the procedure.
When a Person Should Avoid Bowel Preparation
There are certain rules around which bowel cleaning methods can be used in specific situations, which include but are not limited to:
- Low volume 2-L PEG-ELS with ascorbic acid (a type of laxative preparation) should not be given to people with a specific enzyme deficiency known as glucose-6-phosphate dehydrogenase deficiency.
- PEG-3350 (a type of laxative) should not be given to those with conditions that cause abnormal levels of minerals in the blood (electrolyte abnormalities).
- Magnesium citrate (another laxative) should be avoided in people with kidney disease or those at risk of magnesium toxicity, which is a condition caused by excessive amounts of magnesium in the body.
- Oral sodium sulfate, another laxative when given in a single dose, has been associated with issues relating to the stomach and intestines, like stomach pain and diarrhea.
Sodium phosphate is another laxative that is not usually recommended due to its side effects. It should be avoided in people with kidney disease, dehydration, high calcium levels (hypercalcemia), high blood pressure, and those taking certain blood pressure medications known as angiotensin-converting enzyme inhibitors or angiotensin receptor blockers, as these people can develop kidney issues related to phosphate (phosphate nephropathy). Other potential observed complications include increased levels of phosphate in the blood (hyperphosphatemia), increased blood concentration due to dehydration, reduced calcium levels (hypocalcemia), low sodium (hyponatremia), and seizures.
The bowel-cleaning combination of sodium picosulfate/magnesium citrate can cause side effects such as abdominal pain, nausea, and vomiting. Another combination, sodium sulfate and sulfate-free PEG-ELS, has been linked to vomiting.
Who is needed to perform Bowel Preparation?
Your family doctor or gut specialist will decide the best way to clean your bowels for a procedure. Sometimes, they can work together in this decision because your family doctor may know more about your overall medical history, which can affect what methods are safe to use for bowel cleaning. On the other hand, the gut specialist is often the one to make the final call since they know a lot about bowel cleaning methods. They can also teach you how to correctly do this at home. If you’re in the hospital, nurses are very important as they keep an eye on how you’re doing, any complaints or side effects, and ensure the bowel cleaning procedure was done right.
Preparing for Bowel Preparation
When preparing your bowel for medical procedures like a colonoscopy, doctors may use one of three types of solutions: Isosmotic, Hypoosmotic, and Hyperosmotic agents.
Isosmotic agents often involve a product called polyethylene glycol (PEG). This is an inert polymer, meaning it passes through your bowel without being absorbed by the body. There are high-volume and low-volume PEG preparations. High-volume PEG preparations involve drinking 4L of solution, either all at once or in different sittings (called split-dose). They are typically well-tolerated, but 5 to 15% of patients find the large volume or the taste of the solution difficult. Low-volume PEG preparations were created to provide the same effect but in a smaller, more tolerable amount. There is also a sulfate-free PEG solution, which has improved taste and smell.
Hypoosmotic agents also involve a PEG preparation, often mixed with a sports drink and a medication called bisacodyl. But unlike the PEG solutions above, this mixture doesn’t have FDA approval for bowel preparation. It also may result in changes in sodium, potassium, and chlorine levels in your body.
Hyperosmotic agents, like magnesium citrate, oral sodium sulfate, and sodium phosphate, work slightly differently. Magnesium citrate, for example, attracts more water into the intestine to help clean the bowel but it is not typically recommended due to potential side effects like low heart rate, low blood pressure, and drowsiness. Similarly, sodium phosphate is associated with serious side effects and is no longer recommended. On the other hand, oral sodium sulfate is believed to be safer as it does not cause any significant body electrolyte changes.
There are also combination agents such as sodium picosulfate/magnesium citrate and sodium sulfate/sulfate-free PEG-ELS used for bowel preparation. Each of these combinations has a unique way of working and brings possible side effects.
The effectiveness of these preparations can be measured using something called the Boston Bowel Preparation Scale. This scale rates the cleanliness of different sections of the colon, with higher scores indicating better preparation.
How is Bowel Preparation performed
Preparing your bowels for a medical procedure can be done in two main ways. The first way is through a single dose and the second way is through a split dose. A split dose is when the total amount needed is divided into two separate doses. This procedure has been shown to better prepare the bowels for examination and can help the doctors detect polyps or growths in your colon more efficiently.
Usually, the first part of the split dose is taken the day before your procedure while the second part is taken a few hours before your procedure begins. The time gap between the two doses could be anywhere from 3 to 8 hours. Your doctor will give you specific instructions based on your unique needs.
What Else Should I Know About Bowel Preparation?
Having a well-prepared bowel is crucial for effective colonoscopy, a procedure used to inspect the inside of the colon. A good bowel preparation means that the lining of the colon is clean and clear, which makes it easier to find any polyps or abnormal growths. On the other hand, if the bowel isn’t properly prepared, these growths can be overlooked. This might lead to serious health consequences, as some of these overlooked polyps or lesions could potentially be harmful or even life-threatening.