Bloody stool: It is the earliest and most common manifestation of colorectal cancer. Mild cases only show occasional small amount of bleeding, and severe cases can show mucus bloody stool, mucus purulent bloody stool or bloody stool, which is often misdiagnosed as dysentery or hemorrhoid bleeding and delays diagnosis. Abdominal pain: some patients have persistent dull pain with inaccurate positioning as the first symptom or prominent symptoms, and some patients only have abdominal discomfort or bloating. When colorectal cancer is complicated with erosion, obstruction or secondary infection, obvious abdominal colic may occur due to the corresponding increase of intestinal peristalsis and spasm. Some patients showed typical abdominal pain caused by incomplete intestinal obstruction, that is, the pain was paroxysmal colic, which lasted for several minutes, and gas consciously escaped through the pain, followed by exhaust, and then the pain suddenly disappeared. When the elderly have this symptom, colorectal cancer should be considered first.

2. Symptoms of left colon cancer

Because the intestinal cavity of sigmoid colon is narrow and forms an acute angle with rectum, it is prone to stenosis and progressive intestinal obstruction, and there are many intractable constipation, and the number of defecation can also increase occasionally. Because the obstruction is mostly in the lower segment of sigmoid colon, vomiting is mild or absent, while abdominal distension, abdominal pain, bowel sounds and their intestinal types are obvious. When cancer breaks, blood or mucus can be stained outside feces. Due to continuous inflation, ischemia and hypoxia, the obstruction of the proximal intestine can lead to ulcers, perforation, massive blood and abdominal abscess.

3. Symptoms of rectal cancer

The main manifestations are increased stool frequency, thin stool, blood or mucus, urgency of urination, and then heaviness. Because cancer can invade the sacral plexus and cause severe pain. If the bladder is involved, symptoms such as frequent urination, dysuria, urgency and hematuria may occur. Cancer invades the bladder and can form vesicoureteral fistula. Rectal cancer can also cause intestinal obstruction.

4. Symptoms of right colon cancer

Mainly manifested as indigestion, fatigue, loss of appetite, diarrhea, constipation, or constipation and diarrhea alternately, abdominal distension, abdominal pain, abdominal tenderness, abdominal mass, progressive anemia. The location of the mass varies with the location of the lesion. The cecum cancer mass is located in the right lower abdomen, the ascending colon mass is located in the right lower abdomen, the hepatic flexure mass is located in the right upper abdomen, and the transverse colon mass is located near the navel. In addition, there may be complications such as fever, emaciation, perforation and local abscess. At this point, the lesion has entered the most advanced stage.

5. Symptoms of incubation period of colorectal cancer

The shape of feces changes, such as from coarse to fine; The feces turn black or dark red, and the feces become thin and sticky; The frequency of defecation increased, but the feces could not be discharged; Recurrent hemorrhoids, unexplained anemia, weight loss; Unexplained abdominal pain. There is pus or mucus bloodshot in stool, change in defecation habits, frequent defecation or alternating diarrhea and constipation.

Complications of colorectal cancer

1, tumor obstruction

With the enlargement of tumor and the increase of cancer cells, when the tumor expands to a considerable volume, it can cause intestinal lumen stenosis, intestinal lumen narrowing, intestinal content channel obstruction, leading to flatulence, loss of body fluids, electrolyte disorder, infection and toxemia.

2. Intestinal perforation

According to clinical observation, patients with colorectal cancer often have intestinal perforation. General patients and friends will show typical acute abdomen, causing abdominal muscle tension, tenderness and rebound pain. X-ray plain film shows that the crescent-shaped amusement machine under the diaphragm is out of breath, which can be preliminarily diagnosed.

3. Intestinal obstruction

Colorectal cancer is easy to narrow the intestinal cavity due to the gradual enlargement of the tumor, which will form obstacles to the passage of intestinal contents and lead to mechanical intestinal obstruction. But in clinic, the acute intestinal obstruction caused by tumor is not caused by tumor proliferation completely blocking the intestinal cavity. In many cases, on the basis of severe stenosis caused by tumor, local inflammatory edema, food blockage or mannitol preparation in intestine are induced.