Routine Stool Examination_ Physical and Chemical Phase (FOBT) PDF

Republic of the Philippines BULACAN STATE UNIVERSITY Main Campus City of Malolos, Bulacan Laboratory Exercise No. 5 ROUTINE STOOL EXAMINATION: PHYSICAL AND CHEMICAL PHASE (FOBT) Climaco, K...

Republic of the Philippines BULACAN STATE UNIVERSITY Main Campus City of Malolos, Bulacan Laboratory Exercise No. 5 ROUTINE STOOL EXAMINATION: PHYSICAL AND CHEMICAL PHASE (FOBT) Climaco, King Richard P. Del Rosario, Joy Candice Nolasco, Shaina Roshan Mendoza, Kathrina Mae BSMT - 2A Group 2 (Ascaris lumbricoides) Instructor: Mrs. Maria Salome C. Santos Clinical Parasitology - Laboratory  I. Introduction A Routine Stool Examination is a fundamental diagnostic tool utilized to assess the physical and chemical properties of a patient's stool. This procedure aims to identify abnormalities that may indicate gastrointestinal disorders, infections, or other systemic conditions. The physical examination involves the evaluation of the stool's color, odor, and consistency which allows healthcare professionals to distinguish between normal and abnormal characteristics. Moreover, the chemical examination includes the fecal occult blood test (FOBT) that detects the presence of occult (hidden) blood, which is not visible to the naked eye but may indicate bleeding within the gastrointestinal tract. Through this laboratory exercise, students can skillfully perform occult blood determination and report the results accurately, thereby aiding in early diagnosis and treatment. The relevance of a routine stool examination lies in its ability to provide significant clinical insights into a patient's overall health. Its application spans a wide range of conditions, including parasitic infections, malabsorption syndromes, colorectal cancer, and inflammatory bowel disease. By analyzing the stool’s physical characteristics and chemical composition, healthcare professionals can detect early signs of disease, prevent complications, and conduct proper treatments. Thus, routine stool examination is a critical part of diagnostic procedures, offering valuable clinical significance in understanding and managing various gastrointestinal and systemic health issues. II. Overview of the Laboratory Exercise The physical examination of a stool specimen involves a thorough visual and tactile assessment to identify any abnormalities. The procedure involves systematically observing the stool’s appearance. Figure 1 outlines the flow of the process. To preserve its physical integrity, the specimen must be examined within an hour. The examination includes recording the odor, color, and consistency. Consistency can range from hard, formed, or soft to watery, and color changes—such as black, pale, or green—may signal health issues. For example, black or tarry stools could suggest upper gastrointestinal bleeding (Cleveland Clinic, 2023), while pale stools may indicate bile duct obstruction. If blood and mucus are visible, the specimen is classified as "dysenteric" and consistency or color will not be recorded. Colors like blue, red, or purple might suggest the presence of certain medications. Figure 1. Physical examination Additionally, the presence of any visible blood, mucus, or undigested food particles is recorded to assist in diagnosing conditions such as malabsorption, inflammation, infections, or parasitic infestations. These principles aid in diagnosing and monitoring gastrointestinal conditions, leading to appropriate treatment and management. The chemical phase of stool analysis, especially for occult blood detection, relies on the peroxidase-like activity of hemoglobin. Hemoglobin catalyzes the oxidation of benzidine by hydrogen peroxide, causing a color change in the fecal sample. Glacial acetic acid provides an acidic environment that facilitates this reaction. This test, shown in Figure 2, detects hidden (occult) blood, which could indicate colorectal cancer, gastrointestinal bleeding disorders, or other illnesses. The result is interpreted after two minutes based on the color intensity: faint blue for trace amounts, dim blue for +, clear blue for ++, dark blue for +++, and Prussian blue for ++++. Figure 2: Chemical Phase III. Results and Interpretation Specimen Details: Name: Maria Teresa P. Climaco Age: 49 Gender: Female Date of Collection: 09/11/24 Time of Collection: 7:20 am A. Physical Examination Color Brown Odor Pungent Consistency Soft Interpretation: Upon assessment, the stool appears to be a healthy brown color, which is normal. The odor is characteristically pungent but not unpleasant. Its consistency is soft enough to be easily cut and punctured, which is also normal. Overall, the stool specimen shows to be normal with no signs of irregularity, and there are no issues with bowel movements. B. Chemical Examination: Occult Blood Determination  Positive Negative Interpretation: In the occult blood test card on the left, it shows a faint blue color due to the reaction between guaiac (reagent) and hemoglobin present in the stool sample. This indicates a positive result showing a slight presence of hidden occult blood in stool, which can be a sign of colorectal cancer or gastrointestinal diseases. On the contrary, the test on the right shows a negative result indicating that there was no occult blood in the stool, thus having no blue color reaction. IV. Answers to Guide Questions and QFRs 1. Enumerate the different abnormal characteristics of stool with regards to color, odor, and consistency or form and name conditions associated with them. I. Abnormal COLOR/s Cause/Disease or condition associated with it: Black (Melena) Gastrointestinal bleeding, particularly from the upper GI tract (e.g., peptic ulcers, esophageal varices) Red (Hematochezia) Lower gastrointestinal bleeding, including from hemorrhoids, colorectal cancer, or inflammatory bowel disease (IBD) Pale/Clay-colored Bile duct obstruction, liver disease (e.g., hepatitis, cirrhosis) Green Rapid transit through the intestines (diarrhea), or consumption of green foods or medications Yellow (Steatorrhea) Malabsorption disorders, such as celiac disease, chronic pancreatitis, or parasitic infections (e.g., Giardia lamblia) II. Abnormal ODOR Foul, Putrid Parasitic infections (e.g., giardiasis), bacterial infections, or malabsorption syndromes Sour/Fermentative Lactose intolerance, carbohydrate malabsorption, or short bowel syndrome Fishy smell Cholera or other bacterial infections that cause excessive mucus production  Ammoniacal odor Urea-splitting organisms in patients with chronic renal failure Metallic odor Certain parasitic infections or malabsorptive conditions III. Abnormal CONSISTENCY Watery (Diarrhea) Infections (bacterial, viral, or parasitic), irritable bowel syndrome (IBS), or certain medications Hard, Pebble-like Constipation due to dehydration, low-fiber diet, or intestinal obstruction Greasy, Bulky Malabsorption (e.g., celiac disease, chronic pancreatitis), or parasitic infections Mucus-laden Parasitic infections (e.g., Entamoeba histolytica, Giardia), inflammatory bowel disease (IBD), or bacterial infections (e.g., shigellosis) Loose, Frothy Parasitic infections (e.g., Giardia), fat malabsorption (e.g., due to bile duct obstruction), or bacterial overgrowth 2. State the principle of the general principle of fecal occult blood determination. ➔ The principle of fecal occult blood determination is based on detecting hidden (occult) blood in stool samples, which can be an indicator of gastrointestinal bleeding. The test generally involves using chemical reactions to identify hemoglobin, a protein found in red blood cells, in the stool. The most common method is the guaiac-based test, which uses guaiac resin and hydrogen peroxide to produce a color change in the presence of hemoglobin. 3. What are the different indicators that are used in the detection of fecal occult blood? ➔ There are various indicators used in different methods to detect fecal occult blood: 1. Guaiac This indicator is used in the Guaiac-Based Test (gFOBT). It reacts with hemoglobin in the presence of hydrogen peroxide, producing a blue color if blood is present. This method detects heme, a component of hemoglobin, indicating the presence of blood. 2. Antibodies This indicator is used in the Immunochemical Fecal Occult Blood Test (iFOBT or FIT). The test uses antibodies that specifically bind to the globin portion of human hemoglobin. If blood is present in the stool, the antibodies will bind to it, and the test will show a positive result, typically as a color change on the test strip. 3. Quantification of heme and porphyrins  This indicator is used in the Heme-Porphyrin Assay. This method quantifies the heme and porphyrins in the stool, which are indicative of blood. The assay uses chemical reactions to convert heme into porphyrins, which are then measured. V. Updates Using Fecal Immunochemical Tubes for the Analysis of the Gut Microbiome: Potential to Improve Colorectal Cancer Screening by Kertu Liis Krigul et al. (Published October 10, 2021) A recent study by European researchers sought to determine the feasibility of fecal immunochemical assays (FITs) for microbiome profiling in colorectal cancer (CRC) screening. The QuikRead® iFOB Sampling Set was used to collect fecal samples from 30 healthy volunteers aged 22 to 68 who had no known gastrointestinal illnesses or antibiotic use within the previous 60 days. The researchers compared microbial populations from FIT tubes, fresh-frozen samples, and samples preserved in a DNA/RNA Shield stabilizing solution. The results showed that microbial communities in FIT tubes were remarkably identical to those in fresh-frozen samples, with only a 4% variation in general, indicating long-term stability. This shows that combining microbiota analysis and FITs may improve CRC detection, perhaps providing a more sensitive and cost-effective diagnostic technique. In addition to microbiological analysis, the study assessed the fecal samples' physical qualities, such as consistency, color, and odor. These criteria were evaluated to verify that the samples retained the characteristics associated with fresh stool, which is crucial for accurate microbiome analysis. The consistent appearance and odor of the samples over time demonstrated that the sample collection and storage methods had no negative impact on stool integrity. This finding emphasizes the significance of sample quality in microbiome investigations and the potential for integrating fecal occult blood tests with microbiome analysis to improve colorectal cancer detection. VI. References Anand, U., Agarwal, R., & Anand, C. (1994). Test for occult blood. The benzidine reaction: a textbook error. Biochemical Education, 22(4), 212. https://doi.org/10.1016/0307-4412(94)90014-0 Fecal Occult Blood Test (FOBT): MedlinePlus Medical Test. (n.d.). Medlineplus.gov. https://medlineplus.gov/lab-tests/fecal-occult-blood-test-fobt/#:~:text=There%20are%20two%20 main%20types Kertu Liis Krigul, Aasmets, O., Kreete Lüll, Tõnis Org, & Org, E. (2021). Using fecal immunochemical tubes for the analysis of the gut microbiome has the potential to improve colorectal cancer screening. Scientific Reports, 11(1). https://doi.org/10.1038/s41598-021-99046-w Leonard, J. (2020, January 2). Types of poop: Appearance, color, and what is normal. Www.medicalnewstoday.com. https://www.medicalnewstoday.com/articles/320938#normal-poop Melena (Black Stool): What It Means and When To Worry. (2023, June 8). Cleveland Clinic. https://my.clevelandclinic.org/health/symptoms/25058-melena