Stool examination is very important. It is logical - the stool is a major waste product of our body and its composition can give us many important facts about the digestive tract. This article is dedicated to all basic examination procedures that may be used, starting from the interview with the patient.
We should ask the patient about the consistency, color and frequency of stools. Is there a diarrhea, a constipation, or are they alternating each other? When there is such complaint, we should ask about the number of bowel movements per day. The color of stool is also important. Normal stool is brown and we should ask about any abnormality - pale stool, green stool, yellowish greasy stool, black stool or red bloody stool. In addition, it is advisable to ask if the defecation is painful, if the patient suffers from a weight loss and if there is mucus present in stool.
The examiner should inspect the area around the anus and exclude presence of anal fissure, external hemorrhoids or anal fistulas. The examination should proceed with digital rectal examination, which can help us to find internal hemorrhoids, rectal forms of colorectal cancer and it also helps to indirectly examine the prostatic tissue in males.
Most commonly used tests include fecal occult blood test (FOBT), microbiological examination and certain chemical tests. The FOBT is aimed to diagnose traces of blood in stool and so it helps to find early forms of colorectal cancer. Microbiological examination helps us to find infectious microorganisms in the stool and we use it mainly in patients with acute diarrhea. The microbiology can detect microorganism or their toxins (clostridium toxin in pseudomembranous colitis) in the stool and help us to start the right treatment. The presence of parasites or their eggs in stool is classically evaluated under microscope. Modern chemical tests allow us to determine the concentration of pancreatic enzymes (useful in suspected chronic pancreatitis), certain antibodies and even evaluate the presence of Helicobacter pylori in digestive tract. Modern and yet virtually unknown to the public is the examination of faecal calprotectin, which is used in diagnosis and therapy of the inflammatory bowel diseases (ulcerative colitis and Crohn's disease).
Stool examination is especially important in acute diarrhea where we want to confirm or exclude presence of an infectious agent (e.g. campylobacteriosis, salmonellosis, rotavirus infections, pseudomembranous colitis, etc.). Chronic weigh loss may be indicative for exclusion of a parasitic infection and suspicion of colorectal cancer is a clear indication of FOBT. Antigen of Helicobacter pylori in stool is usually investigated after antibiotic treatment of previously already diagnosed Helicobacter to evaluate the effectiveness of the therapy. In chronic pancreatitis, we check the amount of pancreatic digestive enzymes in the faeces to know the severity of pancreatic affection and its ability to produce the digestive enzymes.
The stool examination has practically no disadvantages. However, the need to obtain a stool sample may be somehow discouraging and reduce the patient's cooperation.
Examination of the stool is a non-invasive and painless procedure, which may give us valuable information about many diseases of the digestive tract. Of course, the investigation is rather auxiliary and its results must be always evaluated together with patient's clinical symptoms and results of other performed diagnostic methods.