Diarrhea is one of the most common symptoms of gastrointestinal diseases, especially in patients with gastrointestinal tumors. The detection of diarrhea symptoms in patients with suspected gastrointestinal tumors is very useful for the early diagnosis of tumors. Timely treatment is also beneficial to control the progress of tumor patients and improve the quality of life of patients.
I. Causes
Diarrhea can be produced by any abnormality or deficiency of normal digestion and absorption function of intestine and destruction of intestine, which can be divided into the following categories according to its pathogenesis and causes.
1, exudative diarrhea
There are many causes of exudative diarrhea, which can be broadly divided into infectious exudative diarrhea and non-infectious exudative diarrhea. In non-infectious exudative diarrhea, intestinal tumors are one of the important causes, among which colon cancer, rectal cancer, small intestine lymphoma, intestinal malignant group, etc. are likely to cause diarrhea.
2.Osmolar diarrhea
Diarrhea is caused by the increase of solutes that cannot be absorbed in the intestinal cavity or intestinal absorption dysfunction, causing an increase in osmotic pressure in the intestinal cavity and retaining a large amount of water. There are many causes of osmotic diarrhea, but those caused by malignant tumors mainly include severe liver cancer, bile duct cancer, gallbladder cancer and pancreatic cancer that form long-term bile duct obstruction.
3.Abnormal intestinal function diarrhea
Some tumors, such as medullary thyroid carcinoma, carcinoid syndrome, gastrinoma, etc., can cause diarrhea due to abnormal intestinal function. Cancer diarrhea is more common in Chinese medicine and is mostly caused by the failure of the spleen and stomach in transporting and transforming functions. Clinically, weakness of spleen and stomach is the most common cause, followed by injury by diet and invasion of external evil.
II. Clinical manifestations
The manifestations of diarrhea caused by malignant tumor are often as follows.
1. Age
Malignant tumors causing diarrhea, such as colon cancer, pancreatic head cancer, bile duct cancer, gallbladder cancer, liver cancer, etc. are mainly seen in middle and old age.
2.Onset and course of disease
For those who have acute onset, short course (usually within 3 months), persistent diarrhea rather than intermittent diarrhea, nocturnal diarrhea, with emaciation and anemia, weight loss and increased blood sedimentation after testing, they should be alert to malignant tumors. However, for some patients with prolonged diarrhea, such as those with a disease duration of more than 2 years, the possibility of colon cancer is also less.
3.Fecal traits
Different malignant tumors of diarrhea have different stool characteristics. For example, if the stool volume is low, often accompanied by mucus or blood, and frequent, the possibility of colorectal cancer should be considered. If diarrhea is mainly blood, small intestine lymphoma, colon cancer, malignant group, etc. should be considered. For those with fatty diarrhea, attention should be paid to the presence of pancreatic cancer, etc.
4.Concomitant symptoms
The diarrhea caused by malignant tumor is mostly chronic diarrhea, and often accompanied by abdominal pain, we should pay attention to the nature and location of abdominal pain. Those who have paroxysmal intestinal colic or chronic intestinal obstruction should consider colon cancer more if they are middle-aged or elderly. For those who have chronic diarrhea with fever, anemia and wasting should consider intestinal lymphoma, intestinal malignant group, etc. Those who have weight loss but no fever should pay more attention to the presence of intestinal tumor.
III. Diagnosis and differential diagnosis
Since the causes of diarrhea are complex and the possibility of diarrhea can occur in patients of any age, it is often difficult to diagnose diarrhea, especially the cause of the disease. However, diarrhea caused by malignant tumor sometimes has certain characteristics, so we should look for the pattern carefully and try to make the diagnosis in time.
1. Medical history inquiry
(1) Tumor history and treatment. Those who suffer from digestive system tumor, especially gastrointestinal tumor patients, and suddenly have diarrhea without obvious infection should be considered as diarrhea caused by tumor.
(2) According to the duration of diarrhea, the presence of concomitant symptoms, the effect of general anti-infection treatment, combined with the patient’s age, comprehensive consideration and analysis.
2.Physical examination
For patients with diarrhea, especially those suspected to be caused by tumors, a comprehensive physical examination should be conducted. Besides paying attention to whether the patient has obvious wasting, also pay attention to whether there is anemia, focus on whether there is intestinal pattern and peristaltic wave in the abdomen, whether there is partial intestinal obstruction, also pay attention to whether there is a mass in the abdomen, so as to discover the tumor in the abdomen timely. Anal finger examination is a common examination method, and if a mass and stricture are found, it is highly suggestive of rectal cancer. If there is jaundice, ascites and obvious enlargement of liver, it indicates that diarrhea is related to liver or pancreatic diseases, especially pay attention to the existence of liver cancer and pancreatic cancer.
3.Laboratory tests
The most commonly applied laboratory test for diarrhea is stool examination. Bloody stools can be seen in diarrhea caused by intestinal tumors. For those who do not see obvious bloody stools, stool occultation test should be performed, which is sometimes positive. For those with chronic diarrhea, regular blood tests should be performed, and malignant tumors of the gastrointestinal tract should be considered if they are accompanied by anemia. The examination of tumor markers in serology can often provide useful clinical help for the timely detection of tumors in the gastrointestinal tract.
4.Endoscopy and imaging examination
Endoscopy includes gastroscopy and colonoscopy. For chronic diarrhea, sigmoidoscopy should be performed. If there is a suspected mass above the sigmoid colon, fiber colonoscopy or direct fiber colonoscopy should be performed, and biopsy should be taken for pathological examination. For those who consider diarrhea caused by small intestinal masses, gastroscopy and small intestinal microscopy, aspiration of intestinal fluid and intestinal mucosal biopsy are feasible. ERCP has important value when biliary and pancreatic lesions are suspected.
Gastrointestinal X-ray examination such as barium meal and barium enema are the most commonly used examinations to detect malignant tumors in the gastrointestinal tract, especially barium enema should be used as a routine examination for patients with chronic diarrhea, which is helpful for the diagnosis of colon cancer and so on. Abdominal CT also has high value for tumor diagnosis.
5.Differential diagnosis
The etiology of diarrhea is complex, and there are many diseases causing diarrhea that need to be differentiated. In clinical work, we should make timely differentiation and diagnosis of diseases causing diarrhea, especially tumors, based on detailed medical history, physical examination, necessary laboratory tests and special examinations.
(1) Differentiation of non-tumor diseases that cause diarrhea
There are many types of non-neoplastic diseases that can cause diarrhea, such as the most common intestinal infectious diseases, bacterial dysentery and viral enteritis, which have a clear seasonal onset and are often preceded by a history of unclean diet. Diseases like intestinal tract itself, such as ulcerative colitis, are usually caused by a longer history of intestinal diseases. Some parasitic diseases cause diarrhea in which the patient has a history of exposure to epidemic water. Diarrhea caused by food poisoning, there is often a history of unclean diet, multiple onset of the same meal, etc., generally not difficult to identify.
(2) Differentiation between malignant tumors that cause diarrhea
A variety of malignant tumors can cause diarrhea, but colorectal cancer is the most common one in clinical practice. In addition to diarrhea, the left colon often has intestinal obstruction, accompanied by changes in bowel habits. For right-sided colon, diarrhea, anemia and right-sided abdominal mass are often present, and for rectum, blood in stool is often present. The diagnosis is often rapidly confirmed by rectal examination, sigmoidoscopy, barium enema and barium-air double contrast X-ray, fiberoptic colonoscopy and biopsy. Other non-intestinal tumor disorders that cause diarrhea, such as cancers of the liver, bile and pancreas, are usually not difficult to distinguish after ultrasound, CT, MRI and tumor marker testing.