The colonoscopy is a standard medical procedure used to examine the lining of the large intestine, primarily to screen for colorectal cancer and precancerous growths called polyps. The success of this diagnostic test depends entirely on the quality of the bowel preparation completed by the patient beforehand. The prescribed prep solution, a powerful laxative mixture, is designed to completely clear all solid waste from the colon. This allows the physician a clear, unobstructed view of the intestinal wall, ensuring the procedure can be completed thoroughly and safely.
Common Reasons for Difficulty Finishing the Prep
Patients often struggle to consume the full amount of solution because of the sheer volume required, which for some formulations can be up to four liters. The laxative’s chemical composition, often a polyethylene glycol (PEG) solution, frequently results in a distinctly salty or medicinal flavor. This unpleasant taste can trigger a gag reflex or lead to a strong sense of aversion, making consumption difficult.
The intense osmotic action of the solution can quickly induce physical side effects like nausea, bloating, and abdominal cramping. Experiencing these uncomfortable symptoms can deter a person from continuing to ingest the large volume of liquid necessary for a complete cleanse. This combination of high volume, poor taste, and physical discomfort represents the primary barrier to successfully completing the regimen.
The Direct Impact of Incomplete Preparation
If a person cannot finish the entire prep solution, residual stool or thick fluid will remain coating the colon walls. This material severely impairs the physician’s ability to thoroughly visualize the lining through the colonoscope. When the colon is inadequately cleaned, it is difficult to distinguish a small polyp, which can measure only a few millimeters, from fecal matter.
The clinical outcome of this poor visualization is a significant risk that precancerous polyps will be missed during the examination. Studies indicate that the miss rate for polyps increases significantly when the bowel preparation is rated as inadequate. In such cases, the physician may be forced to stop the procedure early or cancel it entirely. This occurs because the viewing conditions do not meet the necessary safety and quality standards for a reliable screening.
Immediate Steps If You Cannot Finish the Solution
If you are struggling with nausea or the taste of the solution, several techniques can help with ingestion. Chilling the prep solution in the refrigerator can improve its palatability, as cold temperatures dull the taste receptors. Drinking the solution through a straw bypasses a large portion of the taste buds, making the process faster and less offensive.
Taking short, regular breaks between glasses, rather than trying to power through the entire volume at once, may help manage feelings of fullness or nausea. Sucking on a lemon wedge, a clear hard candy, or a piece of ginger helps to clear the unpleasant aftertaste. If repeated vomiting occurs and prevents you from keeping the solution down, stop and immediately contact the healthcare provider or the facility performing the procedure for urgent advice.
Next Steps Following a Failed Prep
If the colonoscopy is cancelled or deemed incomplete due to inadequate preparation, the patient will need to reschedule the procedure. The first step is a discussion with the provider to determine the next course of action and necessary adjustments. For the repeat attempt, the physician will likely customize the prep regimen to address the prior difficulty.
This customization may involve prescribing a different laxative formulation, such as a lower-volume agent, or ensuring the next regimen uses a split-dose approach. A split-dose approach is often found to be more effective and tolerable. In cases where a person has repeatedly failed to complete the liquid preparation, alternative screening methods may be discussed. These alternatives could include a CT colonography, which requires a less rigorous bowel cleanse, to ensure the necessary cancer screening is performed.