Modified and More Rigorous Cleansing Procedure May Better Prepare CF Patients for Colonoscopy, Study Says

People with cystic fibrosis (CF) may require a modified and more rigorous cleansing procedure to prepare their bowels for a colonoscopy screening procedure that allows good visualization, a study reports.

Findings of the study, “A non-randomised single centre cohort study, comparing standard and modified bowel preparations, in adults with cystic fibrosis requiring colonoscopy,” were published in the journal BMC Gastroenterology.

CF is a genetic disorder caused by mutations in the CFTR gene, which provides instructions to make the cystic fibrosis transmembrane conductance regulator (CFTR) protein.

Although CF is mostly associated with respiratory symptoms, gastrointestinal (GI) complications are also known to afflict patients, such as diarrhea, constipation, rectal prolapse, gastroesophageal reflux disease (GERD), and GI cancer.

Colorectal cancer (CRC) in particular is common among CF patients, especially among those who underwent lung transplant. The standard screening procedure for CRC is a colonoscopy, which looks for abnormalities in the rectum and large intestine.

“The diagnostic accuracy, speed, and completeness of colonoscopy depend highly on the quality of the bowel cleansing preparation. Colonoscopy has been proposed as the diagnostic modality of choice in patients with CF, [however] optimal CRC screening has not been established in patients with CF,” the investigators wrote.

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A group of physicians with The Prince Charles Hospital (TPCH) in Queensland, Australia, compared the effectiveness of colon visualization during colonoscopy using two bowel cleansing preparation regimens — a standard and a modified version — in a group of CF patients.

The study involved a total of 65 CF patients who had performed a colonoscopy between 2001 and 2015 at TPCH.  Of this final group, 27 were prescribed a standard bowel preparation prior to a colonoscopy (control group), while 38 were prescribed a modified version of the standard cleansing bowel procedure that was introduced in 2009.

According to the research team, the modified CF bowel preparation protocol starts 14 days prior to a colonoscopy with daily use of an iso-osmotic laxative. The standard bowel protocol does not include this laxative. Then, eight days prior to the screening, CF patients start a low-fiber diet (compared to four days pre-screening in the standard protocol); three days prior to the colonoscopy, colonic purging commences combined with a clear-fluid diet.

Overall, “the modified CF bowel preparation is longer in duration with up to 10 L of colonic lavage over 3–4 days, compared to standard institutional bowel preparation (3–4 L colonic lavage 1–2 days prior to procedure),” the researchers wrote.

Results showed that a higher percentage of CF patients (50.0%) who underwent the modified procedure achieved “excellent/good” scores in GI visualization, compared to the 25.9% using the standard cleansing protocol.

In accordance, a lower percentage of those on the modified bowel preparation procedure attained “poor” scores in visualization cleanse compared to controls — 10.5% versus 44.5%, respectively.

The percentage of patients achieving “fair” GI cleanse visualization scores were similar in both groups: 39.4% in modified version and 29.6% in the control group.

The detection rates of adenomatous polyps (colon polyps) during the first colonoscopy were higher among CF patients using the modified cleansing procedure, compared to those who had undergone the standard cleansing procedure — 50.0% versus 18.5%, respectively.

As expected, colon polyps were more frequently found in older patients (40 or older) compared to younger one — 62.5% versus 24.3%, respectively, highlighting the importance of colonoscopy screenings in middle-age and older patients.

Nevertheless, the prevalence of colon adenocarcinoma was similar in both groups (two patients from each).

“This study primarily highlights that standard colonoscopy bowel preparation produces suboptimal colonic lavage and poorer colonic visualization compared with a modified CF bowel preparation. A longer duration and larger volume of lavage using a modified CF bowel preparation is required to obtain good colonic visualization, in CRC screening or investigation,” the researchers wrote.

“A higher rate of polyps in patients over 40 years of age (versus less than 40 years) was evident at our centre. These results support adults with CF considered for colonoscopy screening at 40 years of age, or prior to this if symptomatic; which is earlier than CRC screening in the non-CF Australian population,” they added.