Does Purgative Bowel Preparation Before Capsule Endoscopy Improve Diagnostic Yield?

3d rendering x-ray capsule endoscopy isolated on black
Researchers compared 2 purgative bowel preparation regimens to analyze their clinical utility before capsule endoscopy.

Use of purgative bowel preparation before capsule endoscopy (CE) does not improve diagnostic yield or small bowel visualization quality (SBVQ) and is associated with lower tolerance in patients with suspected small intestinal bleeding, according to a study in Gastrointestinal Endoscopy.

The multicenter, blinded, randomized controlled trial evaluated the clinical effectiveness of 2 types of purgative bowel preparation compared with a control group that used clear fluid only. The assessments were conducted from April 2015 to December 2019 in outpatients aged over 18 years.

The study participants were randomly assigned to 1 of 3 intervention arms. The patients assigned to arm A (control group) were instructed to take nothing by mouth for 6 hours before the procedure. Patients in arm B (polyethylene glycol [PEG] 2L) were instructed to drink 2L of standard PEG 15 hours before CE and then to continue a clear-fluid diet and remain nil-by-mouth for 6 hours before the CE appointment. Patients randomly assigned to arm C (PEG 1L + sodium ascorbate) continued the clear-fluid-only diet 18 hours before the procedure and were instructed to have the 1L-PEG-based solution 4 hours before the procedure. The arm C patients then remained nil-by-mouth until the CE appointment.

Researchers classified lesions as highly relevant (P2) or less relevant (P0 or P1). The primary endpoint was detection of P2 lesions.

Of 524 patients screened in 5 centers, 229 patients were included in the study. The median age was 60 years (IQR, 48-70), and 47.1% were men.

P2 lesions were observed in 47.6% (95% CI, 41-54.1) of participants overall, and P0 to P1 lesions were found in 28.2% (95% CI, 22.3-34.1) of participants. No statistically significant difference was observed regarding the incidence of P2 lesions (48.7%, 48.0%, and 45.9% in arms A, B, and C respectively, P =.94) or P0 to P1 lesions (28.2%, 32%, and 24.3% in arms A, B, and C respectively, P =.58).

No significant difference was found between overall SBVQ (P =.96) and distal SBVQ among the 3 groups (P =.72). Patients taking PEG 2L reported nausea, bloating, and abdominal pain (10.5%, 21.1%, and 17.3%, respectively) and PEG 1L + sodium ascorbate (10.7%, 11.1%, and 13.9%, respectively).

The control group had a mean visual analogue scale score of 0.7 (95% CI, 0.4-1.1), which was significantly lower compared with scores of 3.5 (95% CI, 3.0-4.1) and 2.6 (95% CI, 2.1-3.1) in arms B and C, respectively (P <.001). More patients in the control arm (74%) reported no discomfort, compared with patients in arms B and C (14.5% and 25%, respectively, P <.001).

Study limitations include terminating the trial early due to an interim analysis; the possibility of an underpowered study that could not detect smaller differences in the diagnosis of clinically relevant P2 lesions; and having included patients with suspected small intestinal bleeding.

“In this blinded randomized controlled trial, the use of PEG preparation prior to CE did not result in improved diagnostic yield or SBVQ,” the study authors noted. “Patients receiving PEG reported more adverse events and lower tolerance compared to patients on clear fluid diet only. Our results do not support routine use of purgative preparation in patients undergoing CE.”


Lamba M, Ryan K, Hwang J, et al. Clinical utility of purgative bowel preparation prior to capsule endoscopy: a multicenter, blinded, randomized controlled trial. Gastrointest Endosc. Published online July 14, 2022. doi:10.1016/j.gie.2022.07.010