Low Fiber Diet During Bowel Prep

A recent prospective, randomized trial (A Mytyk et al. JPGN 2018; 66: 720-24) compared a low fiber diet with a clear liquid diet during a polyethyylene glycol prep prior to colonoscopy. N=184, Median age 15 yrs (range 6-18 yrs).

Low fiber diet included milk, dairy products, some soups, bread and rolls, sandwiches, meat, fish, eggs, pasta, and honey.

Children in both groups were asked to fast for a minimum of 6 hours prior to colonoscopy and their bowel prep was assessed with the Boston Bowel Preparation Scale (BBPS). Bowel prep consisted of PEG 4000 with electrolytes dosed at 66 mL/kg to max of 4 liters.

Key findings:

  • There was no significant difference in BBPS between the two groups
  • Overall, 95.4% of patients had good bowel cleanness (BBPS ≥5)

My take: This study indicates that with a good volume of bowel prep, a less-rigorous diet change may be effective for a cleanout.

Disclaimer: These blog posts are for educational purposes only. Specific dosing of medications/diets (along with potential adverse effects) should be confirmed by prescribing physician/nutritionist.  This content is not a substitute for medical advice, diagnosis or treatment provided by a qualified healthcare provider. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a condition.

Related blog posts:

Big Creek Greenway -not far from McFarland


How Colonoscopy & Preps are Indicative of Patient Activation and Health Care Decision-Making

I found two recent studies on bowel preps interesting primarily because of how they help us understand problems with utilization and problems with patient motivation.

The first study (Clin Gastroenterol Hepatol 2014; 12: 443-50) utilized a 5% random national sample of Medicare claims data.  The authors determined that among 57,597 Medicare beneficiaries 66 years and older that underwent screening colonoscopy (not therapeutic) 24.8% of these procedures were performed in individuals with a life expectancy <10 years.  Given the nature of the study (eg. relying on administrative data), there were several limitations.  However, the implication of the study is that there are a lot of unnecessary colonoscopies.  That is, screening colonoscopies are intended to interrupt a sequence of adenoma to adenocarcinoma that can take years; even when cancer is present, it can take several years before the onset of clinical symptoms.  Currently, the US Preventive Services Task Force (USPSTF) recommends against routine screening in those aged 75-84, precisely because the benefits of screening may be outweighed by the risks of screening.”  The authors note that “people with multiple comorbidities (and therefore lower life expectancy) are more likely to visit multiple providers, which increases the chances of receiving testing.”

The second study (Clin Gastroenterol Hepatol 2014; 12: 451-57) showed that patients with lower “patient activation” are much more likely to have a poor colonoscopy preparation.  Patient activation is defined as “an individual’s knowledge, skill, and confidence for managing his/her own health and health care.”  The author’s note that the “Patient Activation Measure (PAM) is a validated scale developed…to measure this construct.” This cross-sectional study took place in Chicago between 2008-2010 at either an academic practice or a ‘federally qualified health center.’ Key findings:

  • One-third of patients (n=134/462 adults) had suboptimal quality of bowel preparations. Of these, 15% (n=62) were fair quality and 17% (n=72) were poor quality.
  • After multivariable analysis and adjustments, patient activation (OR 2.12) and diabetes (OR 2.45) were independent predictors of suboptimal bowel preparation quality.
  • Health literacy (a measure of cognitive skill) was not correlated with patient activation (a measure of patient engagement).

Also noted in same journal issue: Clin Gastroenterol Hepatol 2014; 12: 470-77.  “In a supervised setting, nurse endoscopists perform colonoscopies (after a minimum of 100) according to quality and safety standards that are comparable with those of physician endoscopist and can substantially reduce costs.”

Take-home messages:

  1. Poor bowel preparations are common.  In studies of adult patients, split-dose preparations can help.  The associated editorial (pg 458-462) recommends delaying case and considering further oral prep or enemas for patients arriving with stool that is not clear or yellow.
  2. Colonoscopies are performed too frequently in some patients and not frequently enough in others.  Thus, something as simple as a colonoscopy is not so simple.

Related blog posts:

Colonoscopy, Split-dosing bowel preps, and Ottawa scores

Adequate bowel cleansing improves the results of colonoscopy.  Since colonoscopy is a big part of gastroenterology/pediatric gastroenterology, a lot has been written comparing bowel preparations.  A recent study has examined a split-dose polyethylene glycol (PEG) preparation (Gastrointest Endosc 2012; 75: 583-90).

This prospective study from a single center in South Korea examined the effectiveness of a split-dose regimen in 366 patients (18 -65 years).  An interval of 3 to 5 hours between the completion of the last dose of the preparation and the start of the colonoscopy had the highest scores for bowel cleansing.  The authors used the “Ottawa Bowel Preparation Scale” for assessing a quality score.  Favorable odds ratios were noted with optimal preparation interval (OR 1.85), amount of PEG ingested (OR 4.34), and adherence with diet instructions (OR 2.22).

Instructions for preparation in this study:

  • 1. Low-fiber diet for 3 days prior
  • 2. Regular diet for breakfast & lunch day prior; soft diet for dinner, then only clear liquids
  • 3. Two liters of PEG on day prior and then two liters early in morning (5-7 am) on day of procedure –NPO for at least two hours prior to procedure.  While taking PEG, patients were instructed to consume 250 mL every 10 minutes.

Ottawa Scale –score right, mid, and left colon:

  • 0    no liquid
  • 1    minimal liquid –no suctioning required
  • 2    suctioning required to see mucosa
  • 3    wash and suctioning needed
  • 4    solid stool, not washable
  • Plus 0-2 points for overall quantity of fluid.
  • Max score 14 points

In this study, a prolonged interval (> 7 hours) between prep and colonoscopy had increasingly higher scores.  Score for 3-4 hours was 4.25; score for 7-8 hours was 5.20 and score for > 8 hours was 5.92.

As alluded to above, individuals who consumed adequate volume of preparation, had good bowel cleansing.  99% of patients who took at least 75% of PEG (> 3 liters) had a satisfactory preparation.  And, 95% of patients who took less than 75% of PEG had an unsatisfactory preparation.  Compliance with diet instruction was associated with a satisfactory prep in 89% and poor compliance was associated with a poor prep in 81%.

While this study identified these risk factors, it is telling that even in a research study, 141 patients had an unsatisfactory preparation (Ottawa scale 6-14); 225 had a satisfactory preparation (Ottawa scale 0-5).

Additional references –bowel preparations:

  • -JPGN 2011; 53: 71. 2 day prep: Miralax 2 gm/kg, bisacodyl 5mg. n=111.
  • -JPGN 2010; 51: 254. Review of bowel preparations
  • -Gastroenterol 2006; 130: 2240. Oral phospho fleets associated with alarming risk of nephropathy. 21 additional cases identified
  • -J Am Soc Nephrol 2005; 16: 3389-3396
  • -NEJM 2003; 349: 1006. acute phosphate nephropathy after oral phospho fleets in a 71yo woman
Additional references –colonoscopy screening:
  • -Gastroenterol 2010; 138: 73, 27 (ed). Overutilization of colon screening in low risk situations and underutilization in high risk situations in clinical practice.
  • -Clin Gastro & Hep 2009; 7: 1217.  Fewer polyps detected as day progresses at a VA hospital n=477 pts. 27% decline in polyp detection.
  • -NEJM 2009; 361: 1179. Review of screening for colorectal cancer.
  • -Gastroenterol 2009; 137: 792. Use of CT colonography -current appraisal.
  • -Ann Intern Med 2009; 150: 1-8. Says endoscopists miss most cancers on right side & colonosopy reduces cancer by ~60% primarily due to left-sided cancers.  Most, 73%, of colonoscopies not done by GI/colorectal surgery in this study.
  • -Gastroenterol 2008; 134: 1570. Update recommendations from ACS, ACR, US Multi-society task force.
  • -Gastroenterol 2008; 134: 1311. Screening in 40-49 detects similar # of adenomas as in older groups (>50) but fewer advanced Ca.

Other references/links:

1. “Take it easy, Doc, you’re boldly going where no man has gone before.”
2. “Find Amelia Earhart yet?”
3. “Can you hear me NOW?”
4. “Are we there yet? Are we there yet? Are we there yet?”
5. “You know, in Arkansas, we’re now legally married.”
6. “Any sign of the trapped miners, Chief?”
7. “You put your left hand in, you take your left hand out. You do the
Hokey Pokey….”
8. “Hey! Now I know how a Muppet feels!”
9. “If your hand doesn’t fit, you must acquit!”
10. “Hey, Doc, let me know if you find my dignity.” and
11. “Could you write me a note for my wife, saying that my head is not, in fact, up there?”