A colonoscopy is a minimally invasive procedure that is widely used for the diagnosis and treatment of colonic disorders. During a colonoscopic examination, visualization of the mucosa of the entire large intestine and distal terminal ileum is usually possible. Bowel preparation is an essential part of a successful colonoscopy. Inadequate bowel preparation is negatively associated with screening or surveillance outcomes, resulting in misdiagnosis or delayed diagnosis. Inadequate bowel preparation may also lead to suboptimal colonoscopy efficiency, prolonged cecal intubation time, decreased cecal intubation success rates, increased withdrawal time, and additional costs [
Lactulose oral solution is used to treat symptoms of constipation. It tastes sweet and has no obvious gastrointestinal side effects. The combined application of lactulose oral solution and PEG has been proven effective for colonoscopy bowel preparation in patients with constipation [
This study was a prospective, randomized, single-blind clinical trial (clinical trial registration number:
A total of 220 patients who underwent a colonoscopy during the period from Oct 2017 to Mar 2018 at the Gastroenterology Endoscopy Center in the Third Affiliated Hospital, Army Medical University, were reviewed. Patients were eligible if they (1) were outpatients requiring bowel preparation for colonoscopy examination; (2) were aged 18-80 years old, male or female; (3) had a physical status class I-III according to the American Society of Anesthesiologists (ASA); and (4) were willing to sign a consent form and able to complete the questionnaires. Exclusion criteria included the presence of (1) allergy to anesthetic drugs; (2) severe heart, lung, liver, or kidney diseases, metabolic disorders (including diabetes), or electrolyte disturbance; (3) intestinal perforation, obstruction, or bleeding; (4) pregnant or lactating women; (5) mental disorders; and (6) dysphagia. The flow chart of the study is presented in Figure
The flow chart of the study.
The enrolled patients were randomly divided into two groups at a ratio of 1 : 1 by a random number table in an envelope. In a single dose, patients were given 2 L of PEG (PEG group) or 2 L of lactulose (Lac group) in the morning for colonoscopy preparation. The researchers who generated the random number table did not participate in the subsequent experiments.
Polyethylene glycol electrolyte powder (Wanhe Pharmaceutical Co. Ltd., China) contained PEG-4000 (118 g), sodium sulfate (11.37 g), sodium bicarbonate (3.37 g), sodium chloride (2.93 g), and potassium chloride (1.48 g), which were reconstituted in water (2 L). The lactulose solution was purchased from Abbott Healthcare Products B.V. (Duphalac, Olst, the Netherlands; 200 mL/bottle).
Patients were instructed to eat low-fiber, low-residue, and easily digestible foods the day before the procedure [
Patients received 2 L of the PEG solution (PEG group) or 200 mL of lactulose followed by an additional 2 L of water (Lac group), to consume orally, at 5:00 AM on the day of the colonoscopy, at a rate of 250 mL every 10-15 minutes within a period of 2 hours. All enrolled patients were given instruction verbally or with an education pamphlet regarding the administration protocol of the bowel-cleansing agents and dietary restrictions. The nurses involved did not participate in subsequent colonoscopy procedures.
All colonoscopies were scheduled between 8:00 AM and 11:00 AM. Patients received midazolam (0.01-0.02 mg/kg), remifentanil (0.4
The colonoscopy was performed by an experienced endoscopist who had previously completed more than 1000 colonoscopies. Bowel cleansing was scored by the endoscopist performing the colonoscopy. The Boston Bowel Preparation Scale (BBPS) was used for assessing the cleansing quality of the bowel preparations [
The Boston Bowel Preparation Scale.
Points | Description |
---|---|
0 | Unprepared colon segment with mucosa not seen due to solid stool that cannot be cleared |
1 | Portion of mucosa of the colon segment seen, but other areas of the colon segment not well seen due to staining, residual stool, and/or opaque liquid |
2 | Minor amount of residual staining, small fragments of stool, and/or opaque liquid, but mucosa of colon segment seen well |
3 | Entire mucosa of colon segment seen well with no residual staining, small fragments of stool, or opaque liquid |
Demographic and baseline patient characteristics, including age, gender, body mass index (BMI), constipation, smoking, drinking, and surgical history, were collected.
Cecal intubation time, colonoscopy withdrawal time, and polyp detection rate were recorded by the endoscopist performing the colonoscopy. Cecal intubation time was defined as the time required from the introduction of the colonoscope to the point where the base of the cecum was reached. Colonoscopy withdrawal time was defined as the length of time taken to remove the colonoscope once the cecum or terminal ileum was reached, including the duration of biopsy and endoscopic treatment. Polyp detection rate was defined as the percentage of procedures where at least one polyp was detected.
Patient tolerability and adverse events of the bowel preparation were obtained with questionnaires completed by the patients before the colonoscopy procedure, which recorded the presence or absence of nausea, vomiting, abdominal pain or fullness, dizziness, palpitation, or other adverse events. The palatability of the bowel-cleansing agents was also recorded.
The degrees of satisfaction were evaluated by patients for the entire bowel preparation process as well as by the endoscopist for the endoscopic procedure, using a 10-point scale with 0 being the least satisfied and 10 being the most satisfied.
SPSS for Windows (version 19.0, SPSS Inc., USA) was used for statistical data analysis. Quantitative data were expressed as
The final study population included 176 patients (84 males and 92 females) with a mean age of
Patient characteristics.
PEG |
Lac |
||
---|---|---|---|
Age (years) | 0.754 | ||
Male, |
48 (54.6) | 36 (40.9) | 0.07 |
Bodyweight (kg) | 0.057 | ||
Height (cm) | 0.053 | ||
Education (high school and above), |
40 (45.5) | 31 (35.2) | 0.167 |
BMI (kg/m2) | 0.312 | ||
Smoking, |
20 (22.7) | 20 (22.7) | 1.000 |
Drinking, |
22 (25.0) | 20 (22.7) | 0.724 |
History of abdominal surgery, |
21 (23.9) | 18 (20.5) | 0.586 |
Constipation, |
23 (26.1) | 24 (27.3) | 0.865 |
Abdominal disease |
27 (30.7) | 16 (18.2) | 0.054 |
There were no significant differences in the proportion of patients who strictly adhered to the administration time requirement (at a rate of 250 mL every 10-15 minutes within a period of 2 hours) and drinking-water requirement (≥2L; all
Bowel preparation characteristics and colonoscopy results.
PEG |
Lac |
||
---|---|---|---|
Meeting administration time requirement, |
83 (94.3) | 77 (87.5) | 0.190 |
Meeting drinking-water requirement (≥2 L), |
76 (86.4) | 77 (87.5) | 0.823 |
Cecal intubation time (s) | 0.692 | ||
Cecal intubation success, |
85 (96.6) | 86 (97.7) | 1.000 |
Patients needing flushing, |
23 (26.1) | 27 (30.7) | 0.504 |
Propofol dosage (ml) | 0.129 |
The comparative efficacy of the bowel preparation was evaluated using the BBPS scoring system. The Lac group had superior bowel cleansing compared to the PEG group, as evidenced by the higher BBPS scores for all segments of the colon (all
Efficacy of bowel cleansing assessed with BBPS score.
PEG |
Lac |
||
---|---|---|---|
Right colon | 0.001 | ||
Transverse colon | 0.017 | ||
Left colon | 0.001 | ||
Entire colon | 0.001 |
The detection rates of polyps and intestinal diseases in the Lac group (30.68% and 36.36%, respectively) were significantly higher than those in the PEG group (12.50% and 13.63%, respectively; both
Detection of polyp and intestinal lesions.
PEG |
Lac |
||
---|---|---|---|
Polyp, |
11 (12.5) | 27 (30.7) | 0.003 |
Intestinal lesions |
12 (13.6) | 32 (36.4) | 0.0013 |
Patients in the Lac group had significantly higher satisfaction scores than those of the PEG group, as evaluated by both patients and the endoscopist (both
The degrees of satisfaction evaluated by patients and endoscopist.
PEG |
Lac |
||
---|---|---|---|
Patient satisfaction | 0.018 | ||
Endoscopist satisfaction | 0.001 |
The administration of the lactulose oral solution, as compared with the PEG solution, was associated with a lower incidence of nausea (23.81% in the Lac group vs. 58.54% in the PEG group,
Comparison of adverse events and tolerability,
PEG |
Lac |
||
---|---|---|---|
Nausea | 24 (58.5) | 10 (23.8) | 0.008 |
Vomiting | 8 (19.5) | 16 (38.1) | 0.079 |
Abdominal pain | 1 (2.4) | 2 (4.8) | 0.623 |
Abdominal fullness | 2 (4.9) | 7 (16.7) | 0.168 |
Dizziness | 2 (4.9) | 4 (9.5) | 0.682 |
Unfavorable palatability | 2 (4.9) | 0 | 0.497 |
Dry mouth | 2 (4.9) | 1 (2.4) | 0.623 |
Palpitation | 2 (4.9) | 1 (2.4) | 0.623 |
Tinnitus | 0 | 1 (2.4) | 1.000 |
Tongue numbness | 0 | 1 (2.4) | 1.000 |
Total | 36 (40.9) | 42 (47.7) | 0.363 |
Adequate bowel preparation is required for diagnostic accuracy and therapeutic safety for colonoscopy procedures [
PEG is a nonabsorbable isoosmotic solution, which passes through the bowel without any net absorption or secretion. Currently, PEG-based regimens remain the first recommendation for bowel preparation. PEG causes no significant change in weight, vital signs, or serum electrolytes, and it is also relatively safe for patients with an electrolyte imbalance or those with advanced liver, heart, or renal disease [
In this study, no significant difference was observed in the proportion of patients needing flushing during the colonoscopy procedure between the PEG and Lac groups. Neither PEG nor lactulose itself is capable of removing bubbles. Thus, there might be a large amount of foam residue in the gut after bowel preparation, and as a result additional flushing is required during the procedure. These data indicated a similar effect of lactulose and PEG on the removal of foam as a bowel-cleansing agent.
Relative to PEG, lactulose tastes sweeter and is well tolerated by patients. In this study, there were no patients in the Lac group who did not ingest the preparation due to poor taste. Also, patients were more satisfied with the lactulose solution for the entire bowel preparation process, likely due to its better taste. In contrast, two patients in the PEG group complained of unfavorable palatability, and one of them vomited as a result of intolerability. PEG was associated with a higher incidence of nausea (58.54%) after administration, which might be related to its unfavorable palatability. Adverse reactions in the Lac group were mainly gastrointestinal symptoms, such as nausea, vomiting, abdominal pain, and abdominal fullness. Importantly, patients who were given the lactulose solution were more likely to develop abdominal fullness, as compared to PEG (16.67% vs. 4.88%). Since the body is able to absorb only a small amount of lactulose, a patient would feel a sense of abdominal fullness and maybe even experience vomiting if substantial amounts of the lactulose solution were ingested within a short period of time. There were similar overall incidences of adverse reactions in both groups, suggesting that the lactulose solution is safe to use for bowel preparations. However, the long-term safety profile of lactulose needs further investigation.
In conclusion, this study demonstrated the higher efficacy, improved tolerability, and acceptable safety of a 2 L lactulose oral solution for bowel preparation as compared with the same volume of a PEG solution. Thus, the lactulose oral solution may be a potential bowel-cleansing agent for use in colonoscopy preparation.
The data used to support the findings of this study are available from the corresponding author upon request.
The manuscript has been presented as an abstract in the Journal of Digestive Diseases. Please refer to the following link:
The authors declare that they have no conflict of interest.
Chun-Xia Li and Yan Guo contributed equally to this work.
This work is supported by the National Natural Science Foundation (Nos. 81472006 and 81171526).