Overview.
A bulge that protrudes from the lumen of the colon is called a colon polyp. It includes all types of lesions that are either neoplastic or non-neoplastic.
Causes
1. Dietary factors
The incidence of colorectal polyps is significantly higher in people who have been eating a high-fat, high protein, low-fiber diet for a long time, and the incidence of polyps is reduced in people who eat more fresh fruits and vegetables as well as Vitamin C.
2. Bile metabolism disorders
Gastroduodenal ulcer gastrojejunostomy and cholecystectomy patients, the flow of bile and discharge time changes, the content of bile acid in the colon increased. Experiments have shown that bile acids, as well as the metabolites of bile acids, deoxycholic acid and lithobionic acid, have the effect of inducing adenomatous polyps or carcinomas in the colorectal mucosa.
3. Hereditary factors
Among colorectal cancer patients, some of them have family history of cancer. Similarly, when someone in the family suffers from adenomatous polyp, the possibility of other members developing colorectal polyp is significantly higher, especially familial polyposis with obvious family heredity. In addition, the incidence of colorectal polyps is also significantly higher in patients who have had cancer in other parts of the body, such as digestive tract, breast, uterus and bladder cancer.
4. Inflammatory diseases of the intestines
Chronic inflammatory lesion of colon mucosa is the main reason for the occurrence of inflammatory polyps, which is most common in chronic ulcerative colitis, Crohn’s disease, amoebic dysentery, intestinal schistosomiasis and intestinal tuberculosis, etc., and is also seen in anastomotic site after colon surgery.
5. Genetic abnormalities
The occurrence of familial polyps may be related to the loss of function and absence of an allele of oncogene called APC in the long arm of chromosome 5. Normally, this allele needs to function simultaneously to inhibit tumor growth. When the gene is absent or mutated, the inhibitory effect on the tumor disappears, resulting in colorectal adenomatous polyposis and carcinoma.
Symptoms
About half of the polyps do not have clinical symptoms, and they are often found by census or autopsy, or discovered only when complications occur, and their symptoms are summarized as follows:
1. Intestinal irritation
Diarrhea or increased frequency of bowel movements, in severe cases, water-electrolyte imbalance may occur, if infection can be seen in mucous blood stools.
2. Blood in stool
Blood in the stool can be of different degrees, such as: polyp bleeding in the lower rectum can be seen with blood in the stool, high polyp bleeding is often mixed with blood or blood clots in the stool, bleeding can be direct blood or blood clots, there are also blood dripping in the stool, and so on.
3. Intussusception or with intestinal obstruction
It is caused by the polyp itself, and even the polyp can be seen prolapsing out of the anus, which is often seen in children, and it can be detached or retracted by itself.
4. Physical signs
Abdominal examination can be palpable mass with pressure pain, most of them are intestinal loops, intestinal tinnitus, and so on, there may be no obvious abdominal signs. Black spot polyposis can be seen in the oral mucosa, lips, perioral, perianal, and the soles of the fingers and feet of both hands have spots of hyperpigmentation.
Examination
1. Histopathologic examination
The pathologic diagnosis of polyp biopsy or excision specimen is crucial in determining further treatment options. Clinicians must pay attention to the following points: ① Sampling The distribution of villous components varies in different parts of the same adenoma, and the degree of heteromorphic hyperplasia varies in different parts. The degree of heterogeneous hyperplasia varies in different parts of the adenoma. Cancer may be central or focal, so the pathological diagnosis of biopsy specimens taken from different parts of the adenoma may not be the same, and the specimens should be taken from many places or several times, and it is better to remove all polyps for examination. The specimen should be fixed correctly and labeled in time, so that the pathologist can identify the head, base and cutting edge of the specimen. If the adenoma is accompanied by heterogeneous epithelial hyperplasia or carcinoma, it can be diagnosed differently due to the difference in experience of the pathologist.
2. Fecal Occult Blood Test (FOBT)
Its overall polyp detection rate is low. Using Reverse Indirect Hemagglutination Fecal Occult Blood Test (RPHA-FOBT) and computerized risk assessment, combined with screening for colorectal cancer in the population, it was found that the RPHA method has higher sensitivity and specificity. The method has a certain detection rate for colorectal polyps.
3. Tumor marker detection
For example, applying monoclonal antibody and immunohistochemistry technology to determine MC3, CA19-9, CEA, CA50 and other tumor-related antigens in tumor tissues; using flow cytometry or microspectrophotometry to determine the DNA content of tumor tissues or analyze the level of DNA ploidy. Abnormalities in these indicators are thought to be related to carcinogenesis, and some of them appear before morphological changes. They can be used to monitor early carcinogenesis, cancer progression and early recurrence. However, the detection of adenomas is still mainly in the research stage, and the prospect of wide clinical application remains to be seen.
4. Rectal finger test
It is the easiest and most reliable method to examine the lower intestine within 7-8cm from the anus. Touching the hard nodule is a reliable indicator of polyp malignancy, but if the polyp site is high, rectal palpation often can not be touched.
5. Sigmoidoscopy
Sigmoidoscopy is the most important method of examining low colorectal polyps, and barium enema can often be used to complement each other.
6. Barium enema imaging
It is not easy to detect small polyps, and it is not easy to show low polyps especially in the lower rectum. Double-contrast barium enema can improve the detection rate of polyps and reduce the misdiagnosis caused by air bubbles in the intestinal lumen. Sigmoidoscopy found polyps > 0.5cm patients, need to further barium enema and fiberoptic colonoscopy proximal colon, often can be found at the same time with colonic lesions, single contrast barium enema on the proximal intestinal polyps sensitivity, compared with the double contrast is low. Therefore, any sigmoidoscopy found adenoma patients should be further examination, the first choice of fiberoptic colonoscopy, such as the inability to check the entire colon, then choose double contrast barium enema examination.
7. Fiber colonoscopy
Fiber colonoscopy is the most accurate and reliable method to diagnose colorectal polyps. More than 90% of the skilled operators can reach the ileocecal part, which can make some estimation on whether the polyps are cancerous or not. Endoscopic smear dye can be found tubular adenoma and villous adenoma. Total colonoscopy should be performed in patients with any polyp detected by sigmoidoscopy, or in patients with recurrence after polypectomy, in order to detect concomitant carcinoma or concomitant polyps in time. About half of the polyps and cancers are missed by gas barium enema. Therefore, fiberoptic colonoscopy should be performed to examine the whole colon before surgery for colorectal cancer in order to promote the discovery of simultaneous tumors and reduce the incidence of early-stage heterochronous and adenomatous carcinomas.
8. Ultrasound of colon
It is a method of continuous transabdominal ultrasound of the colorectum with ultrasound after retrograde irrigation in the colon. The method is sensitive, economical, reliable and without side effects. The report can examine all segments of the colorectum in detail and detect most polyps and cancers without false positives.
Diagnosis
Although adenomas may bleed or bleed in small amounts, they can often be asymptomatic, and regular fecal occult blood tests (FOBs) can reveal a positive result. Further fiberoptic colonoscopy or X-rays or gas-barium imaging in such patients can lead to the diagnosis of adenomas in the occult blood stage. However, not all adenomas develop or have a small amount of occult blood, and 1/3 to 1/2 adenomas do not bleed. Sequential screening with high-risk factors and its optimized protocol can make up for the shortcomings of FOB screening.
1. Diagnosis of high-risk groups
The high-risk group is not clinically symptomatic, and in the asymptomatic stage, the sequential screening program can be applied, using FOB combined with the AD value of high-risk factors as the initial screening. This program has been validated and established through generations, which is simpler and easier to implement, specifically: over 40 years old, ① positive fecal occult blood immunoassay (RPHA-FOB); ② history of colorectal cancer in relatives of the first degree; ③ history of cancer and history of polyps and adenomas; ④ two or more positive symptoms in the six symptoms in the item as a number of positives, including: mucus blood in the stools, chronic constipation, chronic diarrhea, history of appendiceal disorders, If any one of the four symptoms is positive, the patient is considered to be at high risk for fiberoptic colonoscopy.
2. Diagnostic steps
To further confirm the diagnosis from the screened high-risk group, gas-barium double contrast and fiberoptic colonoscopy can be used to confirm the diagnosis by histopathology. If the tumor is found to be less than 1cm in endoscopic examination, it will be removed and pathologically examined; if it is difficult to remove it for the first time if it is more than 1cm, then tissue biopsy will be taken for pathological diagnosis.
3. Follow-up after resection
In small (<1cm) tubular adenomas with mild or moderate atypical hyperplasia, the chance of subsequent colorectal cancer is not higher than that of the general population, so regular colonoscopy can be designed for this group of patients with a longer follow-up period.
Fiberoptic endoscopy is clearly more diagnostic than gas-barium X-ray and can be both diagnostic and therapeutic, but definitive diagnosis is still determined by pathologic examination.
Treatment
Because the nature of polyps is difficult to determine from the naked eye, so generally found to be surgically removed or cut for pathological diagnosis, due to the location of polyps or adenomas size, number, with or without tips and the nature of polyps and choose different treatment options.
1.Surgical methods
(1) Loop coagulation method: firstly, suction the mucus and fecal water around the attached polyp, draw out and inject air to replace the hydrogen and methane that may be contained in the intestinal tract, in order to prevent the explosion of electrocauterization, and then open the loop of wire near the polyp, to avoid too close to the intestinal wall, and damage the intestinal wall and cause death and perforation, and then tighten the loop of wire, and then choose the different electric current according to the thickness of the tip, and then don’t be too fast in cutting, and then cut the wire slowly and stop the hemorrhage perfectly.
(2) biopsy forceps coagulation cutting method for 0.5cm wide base lesions, biopsy forceps bite all the way down, up so that the base of the curtain-shaped narrow pseudotip, followed by electric current coagulation for a few seconds, the local gray-white can be biopsy forceps bite tightly pull down the tissue to send for pathology examination.
(3) Electrocoagulator cauterization method, mostly for the lesions below 0.5cm, mostly benign, for those who can not be excised by forceps, can electrocoagulation hemostat contact with coagulation current cauterization excision. However, do not go too deep to avoid perforation or delayed perforation, the latter can occur 2 to 7 days after surgery.
(4) Surgical treatment Surgical treatment of polyps and polyposis generally includes: local resection, intestinal wall resection, intestinal segmental resection, subtotal colon or total colorectal resection. Depending on the number of polyps, the presence or absence of the tip and where it is located: ① there is a single tip for endoscopic laparoscopy, electrocautery (coagulation) or ligation removal. For the larger size, it is not easy to perform lap resection or incision removal, can also choose the intestinal wall, intestinal segment resection. ② non-tibial or widespread, located in the abdominal cavity below the reflex for local excision, reflex above the incision of the intestinal wall, including the base of the intestinal wall and resection or intestinal segmental resection. ③ adenomatosis, including familial, non-familial, Gardner and Turcot’s disease have numerous intestinal tumors, easy to cancer and early age, such as familial adenomatosis generally before the age of 50 years are all cancer, it is advocated that diagnosis of this disease, total colorectal resection, ileostomy, but to the younger patients with lifelong life inconvenience, it is advocated that the total colorectal resection ileorectal anastomosis. Postoperative follow-up should be close. Partial resection of the rectum plus mucosal stripping of the residual rectum, preservation of the lower rectal muscular tube, ileum and lower rectum direct anastomosis. In short, to retain the function of the anus, although to the operation to add some difficulty, but can avoid lifelong ileostomy is possible, but also easy to be accepted by the patient.
2. Surgical options
(1) endoscopic excision of clipped polyps and non-clipped polyps clipped polyps in the colonoscopy together with the removal of the trap, non-clipped polyps can be removed by electrocautery, large polyps can be injected with saline under the mucosa. Postoperative bleeding is a common complication after removal by electrocautery.
(2) Surgical resection Chorionic broad-based adenomas of more than 2 cm should not be resected by colonoscopy, and surgical resection is preferred. If the tumor is located above the peritoneal reflex and cannot be removed endoscopically, it should be treated directly as colorectal cancer, because more than one third of such patients have invasive carcinoma; if the tumor can be removed endoscopically, it should be carefully examined pathologically after resection, and it is advisable to carry out radical surgery if invasive carcinoma is found. Those located below the peritoneal reflex can be resected locally via anus or sacrum.
(3) Principles of treatment of adenoma carcinoma ① Local excision is sufficient for carcinoma in situ which is confined to the mucous membrane layer, but pathological confirmation is required. Malignant polyps are adenomas with cancerous infiltration, invading the mucosa and submucosa, and colonoscopic resection is prone to residual and lymph node metastasis, therefore, it is advocated that those who are confirmed to be malignant should be operated again. For small flat tumors, polypectomy can be performed first, and if malignancy is suspected during endoscopy, surgical resection is required. If malignancy is suspected during endoscopic examination, surgical resection is needed. 3～6 months follow-up after removal of malignant tumor, and if there is recurrence, surgery should be performed again to resect the intestinal segment. (iii) Invasive carcinoma When the carcinoma penetrates the submucosa, there are different opinions on the management. The choice of surgery mainly depends on the risk of cancer metastasis and recurrence.