Rectal Effluent as a Research Tool

Abstract

Studies of localized secretions are generally superior to those of blood because they contain higher concentrations of molecules specific to the organ of interest. A common method used to analyze localized secretions is lavage. The flow of fluid over the lining of a cavity picks up both cells and soluble factors, and the effluent can be collected for study. Gastrointestinal (GI) lavage is easily and noninvasively performed by the administration of gut lavage solutions such as those routinely given to patients prior to colonoscopy, with GI lavage fluid being the copious, watery rectal effluent subsequently induced. Residual effluent is currently suctioned from the colon and discarded during colonoscopy. With millions of routine colonoscopies performed per year, GI lavage fluid is a rich and largely untapped resource for basic and clinical research. Rectal effluent can also be easily collected in a toilet receptacle without need for a colonoscopy. Rectal effluent generated in this manner has been used to study diarrheal disease, mucosal immunology, inflammatory bowel disease, celiac disease, and cancer. It is often referred to as gut lavage, colon lavage, GI lavage, or whole gut lavage fluid, which makes it challenging to locate previous studies in the literature and there are currently no comprehensive reviews of its use as a research tool. This review attempts to fill this void by discussing previous applications of rectal effluent in research and the methods that have been developed for its collection, stabilization, and analysis.

Use of Omics Technologies for the Detection of Colorectal Cancer Biomarkers

“…Proteomics displayed the worst results of all BLF biomarkers, since the identified proteins are not CRC-specific. For instance, Adnab-9 was found increased in patients with a high risk of CRC, but was also raised in coeliac patients' stools [102]. Finally, haemoglobin was increased in BLF from CRC patients, but was also increased in patients with inflammatory bowel disease and diverticulosis [109].…”

“…Once there, saline solution is applied directly to the area of the lesion to obtain the bowel lavage fluid (BLF), which contains a high concentration of cells in contact with this lesion. BLF presents some advantages in front of stool samples, such as lower bacterial interference and lower food leftovers, easier handling in the laboratory, less variability because of the different times in the bowel and water quantity and, finally, less protein degradation [102]. Nowadays, the use of BLF is not extended, although it is a very useful sample with high potential for new biomarkers that needs to be studied.…”

Isolation and Characterization of Extracellular Vesicles in Human Bowel Lavage Fluid

“…Bowel lavage fluid (BLF) is obtained during colonoscopies by direct application of saline serum to the injury area in the colon, enriching it with injury-area cells [ 16 ]. Few studies have been conducted using this sample type for CRC research, with most studies focusing on the presence of genomic biomarkers such as an increase in p53 and K-ras mutations, an increase in mutations of the TGFβ type II receptor and APC [ 17 , 18 ], the presence of aberrant methylation in CpG islands in a gene panel (miR-124-3p, LOC86758, and SFRP1) [ 19 ], and the presence of syndecan-2 methylation [ 20 ].…”

“…Few studies have been conducted using this sample type for CRC research, with most studies focusing on the presence of genomic biomarkers such as an increase in p53 and K-ras mutations, an increase in mutations of the TGFβ type II receptor and APC [ 17 , 18 ], the presence of aberrant methylation in CpG islands in a gene panel (miR-124-3p, LOC86758, and SFRP1) [ 19 ], and the presence of syndecan-2 methylation [ 20 ]. BLF presents some advantages over other samples types such as stool because it is subject to less bacterial and food interference, is easier to handle, presents less variability because of water quantity and time in the bowel, and is less subject to protein degradation [ 16 ]. Nowadays, BLF is rarely used, but this type of sample has a great potential as a CRC research tool and could be studied as possible biomarker source for CRC [ 16 ].…”

Comparative Proteomic Analysis of Whole-Gut Lavage Fluid and Pancreatic Juice Reveals a Less Invasive Method of Sampling Pancreatic Secretions

“…The process of whole-gut lavage using a purgative solution prescribed for colonoscopy has been used in the past to examine various specific protein markers in many gastrointestinal conditions. 15 The purgative causes an influx of water into the bowel and the resulting effluent is a lavage of the entire gut. This fluid, referred to as whole-gut lavage fluid (WGLF), can be collected either non-invasively by means of a toilet receptacle or during colonoscopy via endoscopic suction.…”