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PWE-161 The Macrogol Drink Test To Distinguish Functional Constipation (fc) And Constipation Predominant Irritable Bowel Syndrome (ibs-c): Underlying Mechanisms Demonstrated Using Mri
  1. C Lam1,
  2. G Chaddock2,
  3. C Hoad2,
  4. C Costigan3,
  5. E Cox2,
  6. S Pritchard2,
  7. K Garsed4,
  8. L Marciani2,
  9. P Gowland2,
  10. R Spiller1
  1. 1NIHR Nottingham Digestive Diseases Biomedical Research Unit, Nottingham, UK
  2. 2University of Nottingham, Nottingham, UK
  3. 3Nottingham University Hospital Trusts, Nottingham, UK
  4. 4Royal Derby Hospital, Derby, UK


Introduction Patients with constipation may have either FC or IBS-C which require different treatments. They are often dissatisfied with their treatment because diagnosis relies on symptoms which frequently overlap.

Methods 46 CC patients (24 FC and 22 IBS-C), age 18–68 years, unresponsive to simple laxatives, were compared with 11 healthy volunteers (HV). Whole gut transit (WGT) was assessed using a MRI scan 24 h following ingestion of 5 marker pills as previously validated. Patients then consumed 1 litre of macrogol (MCG) followed by hourly MRI scans for 4 h and scored bowel symptoms from 0–10 (none-severe). Colonic movements were assessed using a motility index (MI) based on colonic wall movement and hypersensitivity index (HI) was calculated as bloating symptom/ascending colon (AC) volume.

Results Mean (SD) See Table 1. FC and IBS-C have slower WGT and higher HI than HV. FC showed significantly greater fasting SBWC, AC volume and reduced MI following ingestion of MCG compared to HV and IBS-C. Moreover, FC showed impaired response to MCG with longer time to first bowel movement and reduced stool frequency on the study day when compared with HV and IBS-C. Time to 1st bowel movement correlated significantly with AC volume 2h post MCG, r = 0.44, p = 0.004 and fasting SBWC,r = 0.34,p = 0.035. Using a cut-off >230 min distinguishes FC from IBS-C with sensitivity 55% and specificity 95%; this needs validation in a repeat study.

Abstract PWE-161 Table 1

Conclusion Time to first bowel movement >230 min makes IBS unlikely and should help target treatments. Our MI studies show this is dueto greater motility response to distension in IBS-C who has lower fasting SBWC and AC volumes versus FC. IBS-C showed similar features to HV but can be distinguished by greater HI following distension which suggest hypersensitivity. This inexpensive test done without MRI could help clinicians to distinguish these 2 conditions.

Disclosure of Interest C. Lam: None Declared, G. Chaddock: None Declared, C. Hoad: None Declared, C. Costigan: None Declared, E. Cox: None Declared, S. Pritchard: None Declared, K. Garsed: None Declared, L. Marciani: None Declared, P. Gowland Consultant for: Merck, Ironwood, Unilever, R. Spiller Grant/research support from: Lessaffre, Ironwood, Consultant for: Almirall, Astellas, Danone and Sanofi, Conflict with: Free drug for clinical trial from Norgine.

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