[Fat Bear Science] This is a science popularization with "flavor"...

Before starting today's science popularization

Fat Bear will tell you a story first

Small stools are placed

Fat Bear Storytelling

Master Liu just turned 50 this year. Due to irregular eating habits, he occasionally felt stomach pain. He thought it was an old stomach disease and took a painkiller to relieve it.

Recently, when he was defecating, he accidentally discovered that his stool was extremely black, almost like tar. He was very surprised and decided to go to the hospital for a check-up.

After arriving at the hospital, the doctor asked him about his medical history and then asked him to do a routine stool test. After the test, it was found that the stool was positive for occult blood, and then further other tests were done, and finally it was diagnosed as gastric cancer.

When Master Liu's neighbor Sister Zhang heard the news, she immediately became nervous. Sister Zhang had just given birth to a child half a year ago and also found that her stool was black. She rushed to the hospital for a check-up, and the result of fecal occult blood was negative, and other indicators were normal.

Ms. Zhang had a false alarm, but she still wondered why the stools were all black, so why were the results different? Could it be that the test was wrong? My child had stools several times a day, and sometimes they were green and very watery. Was there any problem?

With these questions

Ahem...

Today we will talk about a very visual topic

Poop

Kind tips

If you feel unwell

Please ask Fat Bear for eyewash

Yu Yao is the chief technician of the Medical Laboratory Department of Chongqing Cancer Hospital. He has been engaged in laboratory work for more than 7 years and has been actively engaged in the promotion of medical knowledge as a department correspondent for a long time. In 2015-2016, he was responsible for a popular science project of the Science and Technology Commission of Sha District and completed it. In 2016-2017, he participated in a popular science project of the Science and Technology Commission of Sha District as the second participant. He wrote the paper "Empirical Research on Various Popular Science Models in Community Health Education" and won the third prize in the essay solicitation activity of the Chongqing Science Popularization Work Theory Seminar in 2016.

Hello everyone, I am a pile of poop. Everyone calls me stinky poop. Because of my bad smell, everyone stays away from me. But usually when I have diarrhea, constipation, etc., people start to pay attention to me.

First, let me tell you where I came from. In fact, my predecessors were all kinds of delicious food, which were chewed and chopped into small pieces in the mouth, entered the stomach and intestines, and were converted into small molecules that can be dissolved in water by enzymes contained in various digestive juices such as gastric juice and pancreatic juice. After digestion, the chyme is formed and enters the small intestine. In the small intestine, the nutritious small molecules (glucose, amino acids, etc.) are absorbed into the blood.

The remaining residue enters the large intestine for final absorption of nutrients and some water, and the remaining food residue enters the sigmoid colon of the large intestine for storage. At the appropriate time, the sigmoid colon sends the residue to the rectum, and then the person feels the urge to defecate, and the anal sphincter opens, and the food residue in the rectum is discharged, which is the legendary defecation. This is my life, from the entrance to the final discharge, it takes about 12 hours.

Because I travel through various digestive organs in the human body, when minor problems occur in these organs, such as inflammation, pathogenic bacteria invasion, parasitic infestation, or bleeding in some parts of the body, some abnormal substances will be produced and excreted from the body along with me as a signal for people to discover them early.

When the gastrointestinal tract, pancreas, liver and gallbladder function poorly, my shape and composition also change. Therefore, by examining me, we can understand whether the digestive tract and the liver, gallbladder, pancreas and other organs leading to the intestines have inflammation, bleeding, parasitic infection or function.

Usually, in the hospital, doctors will check my characteristics, color, occult blood, white blood cells, red blood cells and parasites. Of course, some hospitals now also check transferrin and Helicobacter pylori for further diagnosis. If the patient is more serious, the doctor will culture me according to the situation to understand whether the distribution of intestinal flora is reasonable and check whether there are pathogenic bacteria in my composition to prevent and treat intestinal infectious diseases.

Next, let me introduce my appearance. Under normal circumstances, my color is yellow (or yellow-brown), has a bad smell, and also contains a small amount of mucus. The daily excretion of adults is 100-300g, and the stool is yellow, soft or semi-formed. The feces of infants are golden yellow or yellow-green.

My yellow color is because the blood cells in the human body are constantly renewed every day. The red pigment of some aging blood cells first turns into green pigment, and then turns into yellow pigment. A small part of the yellow pigment can be excreted from the body through urine, while most of it goes through the liver to the intestines and is then processed by bacteria into brown or fecal yellow.

When abnormalities occur in certain parts of the body, my appearance will first show corresponding abnormalities. If you don’t believe me, come and see (for the sake of your eyes, I won’t provide pictures).

Mucous stool

Mucus often adheres to the surface of feces and is seen in various types of enteritis, bacterial dysentery, amoebic dysentery, acute schistosomiasis, etc.

Mucus, pus and blood in stool

It often appears in the feces of patients with inflammation of the lower intestine, such as dysentery, ulcerative colitis, colon cancer or rectal cancer. The feces of patients with bacterial dysentery are often dark red with a fishy smell, mainly mucus and pus and blood, with less feces; the feces of patients with amoebic dysentery are dark red jam-like, mainly blood, with more feces and a special fishy smell.

Watery stool

Various infectious diarrhea or non-infectious diarrhea are common, especially acute enteritis. Children with enteritis may have green watery stools. If there is a large amount of yellow watery stool containing membranous substances, pseudomembranous enteritis should be considered.

Tarry stools

The stool is brown or black, soft, and shiny, and the occult blood test is strongly positive. Due to upper gastrointestinal bleeding, the degradation products of red blood cells destroyed by gastric acid and the sulfide produced in the intestines are transformed into black iron sulfide under the action of bacteria. Tarry stools may appear when the amount of upper gastrointestinal bleeding is 50-70ml.

Bloody stools

It is more common in bleeding in the lower digestive tract, such as rectal or colon polyps or tumors; anal fissures and hemorrhoids; eating too many tomatoes, watermelons, red peppers, etc. can also cause the discharge of red-appearing feces, so you should be careful to distinguish them.

White clay stools are grayish white, mostly due to bile duct obstruction, reduced or absent bile entering the intestines, and are seen in patients with obstructive jaundice. Barium meal radiography can also cause stools to appear grayish white.

Someone asked, why is the color of my stool the same as others, but the results are different?

Our skin color can sometimes change due to food or medication.

For example, green stool is common when eating a lot of green vegetables. Infant enteritis, indigestion, and accelerated intestinal peristalsis can also cause green stool. Taking certain Chinese medicines can also cause green stool.

In addition to being seen in amoebic dysentery and intussusception, jam-colored stools can also be caused by consuming large amounts of coffee, cocoa, cherries, chocolate, etc.

Black stools, dull in luster, are seen in medicinal charcoal, potassium bismuth citrate, iron, etc. Red stools are sometimes caused by eating foods with more red pigment, such as tomatoes, red pitaya, etc. When black or red stools appear and bleeding is suspected, occult blood tests can be used to identify it, combined with the patient's diet or medication.

Someone asked again, what is the occult blood test?

Occult blood refers to a small amount of bleeding in the gastrointestinal tract that is not visible to the naked eye, and a small amount of red blood cells have been digested and decomposed, so intact red blood cells cannot be found under a microscope. The inspector uses chemical or immunological methods to check and identify the presence of blood or hemoglobin in the stool.

Fecal occult blood test is of great value in the diagnosis of gastrointestinal bleeding. In the case of gastrointestinal ulcer, drug-induced gastric mucosal damage (such as taking aspirin, indomethacin, glucocorticoids, etc.), intestinal tuberculosis, Crohn's disease, ulcerative colitis, colon polyps, hookworm disease, and gastric cancer, colon cancer and other digestive tract tumors, the fecal occult blood test is usually positive, so it must be combined with other clinical data for differential diagnosis.

In the case of peptic ulcer, the positive rate is 40%~70%, which is intermittently positive. After the ulcer is treated, when the stool appearance is normal, the positive occult blood test can still last for 5~7 days. After that, if the bleeding stops completely, the occult blood test can turn negative. In the case of digestive tract cancer, the positive rate can reach 95%, which is continuously positive.

Currently, most laboratories at home and abroad use immunological methods to detect occult blood. However, immunological occult blood tests mainly detect lower gastrointestinal bleeding, and some upper gastrointestinal bleeding cannot be detected.

reason

① Hemoglobin or red blood cells are degraded, denatured or completely digested by digestive enzymes and no longer have their original immunogenicity.

② Excessive bleeding causes excess antigen in the reaction system and the prozone phenomenon occurs.

③ The patient's hemoglobin antigen does not match the monoclonal antibody. Therefore, sometimes the stool looks like tar, but the immunoassay is negative or weakly positive. At this time, the original diluted stool needs to be diluted 50 to 100 times and redone or retested with a chemical method.

Therefore, a new detection method, fecal transferrin, emerged.

Research results in recent years have shown that it is quite useful to detect other blood components in stool other than Hb as a marker of gastrointestinal bleeding alone or in combination. When gastrointestinal bleeding occurs, a large amount of transferrin (Tf) may appear in the stool. The combined detection of the two has significant clinical application value in screening for early colorectal cancer and can improve the detection rate.

In addition to transferrin, Helicobacter pylori can also be checked through feces. It is a Gram-negative spiral microaerophilic bacillus that can be transmitted through fecal-oral, oral-oral, and close contact, and its infection often clusters in families.

Helicobacter pylori infection is an important pathogenic factor of chronic gastritis, gastric ulcer, duodenal ulcer, and upper gastrointestinal tumors. The World Health Organization has listed it as a Class I carcinogen.

Studies have shown that infected people who receive treatment as early as possible can achieve good clinical results, otherwise they are very likely to be infected repeatedly. Therefore, early diagnosis and early treatment are of great significance.

After reading my self-narration, will you have a deeper understanding of me? Today's self-narration ends here. I hope to have the opportunity to talk to you about prevention next time (Fat Bear has consciously entered the small dark room)

Text/ Fat Bear Picture/ Internet (Please contact to delete) Reviewer/ Yu Yao

Original article, no reproduction without authorization

Member of China Medical We-Media Alliance

Science Popularization China Co-construction Base

Chongqing Science Popularization Base/Chongqing Health Promotion Hospital

Chongqing Municipal Science and Technology Commission Science and Technology Communication and Popularization Project

National Health Commission National Basic Public Health Service Health Literacy Project