Case Presentation: An 89-year-old man with a past medical history of Parkinson’s disease (PD), achalasia status post botulinum toxin, and prior stroke presented with two episodes of hematochezia, for which colonoscopy was indicated. The patient had oropharyngeal dysphagia (OD) secondary to PD that was recently diagnosed via an outpatient modified barium swallow study. During hospitalization, the patient required thickened liquids to reduce aspiration risk. Because the patient declined nasogastric tube (NGT) insertion, there was no feasible way to administer the large-volume ingestible bowel preparation safely. After a discussion with pharmacy, a modified bowel-prep strategy was developed. Fourteen packets of powdered polyethylene glycol 3350 (PEG; brand name Miralax) were mixed with patient’s approved nectar-thickened clear liquids and administered in divided doses over two days. The patient tolerated the regimen without side effects. The patient was adequately prepped for colonoscopy and ultimately found to have a new sigmoid mass. This case highlights a practical way to safely prepare patients with OD for colonoscopy without an NGT.
Discussion: Dysphagia is common among older adults and often complicates inpatient colonoscopy preparation. Geriatric patients are often recommended to undergo two-day bowel preparations [1], as up to 10-25% of all colonoscopies are cancelled due to inadequate bowel prep [2]. Administration of the standard large-volume oral liquid PEG bowel preparation is usually via NGT in OD patients [1], however NGTs are uncomfortable and impractical in some populations such as patients with dementia, who may not tolerate NGT placement. Also, this method can increase aspiration risk [3, 4].PEG 3350, the main ingredient in both Miralax and Golytely, is an inert, non-absorbable osmotic polymer whose efficacy relies on retaining water within the intestinal lumen. A key distinction relevant to dysphagia diets is the type of thickening agent used. Nectar-thickened liquids use xanthan gum, which maintains a consistent viscosity by forming a smooth gel-like matrix in the liquid; because the matrix is chemically stable, added solutes (like PEG) do not disturb it, so the liquid stays consistently thick [5]. In contrast, starch-based thickeners thicken by absorbing water, creating only weak interlinking bonds between starch granules. When PEG is added, it draws water away from the swollen starch granules, causing them to shrink and break apart, resulting in a rapid loss of viscosity, nullifying the starch’s thickening abilities and therefore increasing risk of aspiration [5]. Most studies on medication modification for dysphagia patients involve crushing tablets and mixing them with thickening agents; there is little to no research on using powdered medications (like Miralax) mixed into thickeners [6, 7, 8, 9].This case supports the feasibility, safety, and practicality of using powered PEG mixed with xanthan gum-based nectar-thick liquids as an alternative to large-volume liquid colonoscopy preparation. Drawbacks to this method include longer prep time while patients are on a clear liquid or low residue diet and the lack of a commercially available mixture. Additionally, further studies are needed to determine optimal dosing and validate efficacy.
Conclusions: Nectar-thickened (xanthan-gum-based) liquids are compatible with powdered PEG 3350 and can enable safe oral colonoscopy preparation in patients with oropharyngeal dysphagia.