1, etiology and pathological mechanism: colonic redundancy causes constipation of chronic transmission type, is caused by colonic incompetence, that is, colonic dysplasia or obstructive constipation. Scholars at home and abroad generally believe that colonic redundancy constipation and congenital megacolon is also an abnormal disease of the enteric nervous system. Foreign scholars have used histochemical methods to find giant ganglia or ectopic nerve cells under the mucosa of the colon in patients with constipation. Domestic scholars also found that the content of vasoactive intestinal peptide (YIP) in the colonic intermuscular plexus was reduced, the content of substance P was significantly reduced, and the content of S-l00 protein was increased. Wang et al. found that the nitric oxide (NO) synthase-positive fibers in the colonic wall of patients were significantly increased, while the SP-positive fibers were significantly reduced, thus suggesting that the disturbance of intestinal NOergic nerves may have a relationship with the occurrence of intestinal motility disorders. A study by Tomita et al. found that NO as a neurotransmitter inhibited the slow-transmitting constipated colon more strongly than the normal colon. Thus, the colonic weakness or poor or impaired colonic dynamics breeds constipation. 2, the type of colonic redundancy: it is generally believed that the normal anatomical length of adult ascending colon is 15 cm, transverse colon 55 cm, descending colon 20 cm, sigmoid colon 40 cm. If the length of any section of ascending, transverse, descending colon or sigmoid colon exceeds 35% to 40% of the standard value, it can be diagnosed as colonic redundancy. If the range of motion of the transverse colon exceeds the iliac crest and the range of motion of the sigmoid colon reaches the right upper abdomen or right lower abdomen, it is also considered to be colonic redundancy. Colonic redundancy can occur in all segments of the colon and can be single or multiple segments. According to the location and extent of the redundant colon, colonic redundancy can be divided into three types: type I is redundancy of a single segment of the colon; type II is redundancy of two segments of the colon; type III is redundancy of three or four segments of the colon, including redundancy of four segments of the colon, that is, total colonic redundancy. 3. Complications of colonic redundancy: (1) intestinal torsion or perforation, with sigmoid colon torsion being more common, mostly occurring in elderly people over 60 years old. (2) intestinal obstruction, due to the redundant colon and the mesenteric and circumstantial adhesions, resulting in twisting, angulation, contracture and stenosis of the intestinal tube, resulting in acute adhesive intestinal obstruction, mostly in the left side of the transverse colon and splenic flexure, often requiring emergency surgery or fecal obstructive intestinal obstruction due to the redundant colon with colonic motility weakness and long-term constipation. (3) Idiopathic intractable constipation caused by redundant colon mainly occurs in two categories, one for children and one for adults. It is generally believed that the causes of constipation caused by redundant colon are: ① Due to the redundant and twisted colon, stool stays in the colon for a longer period of time and excessive absorption of water in the stool, resulting in dry stool that is not easily excreted. Long-term constipation and heavy use of laxatives can aggravate the relaxation and lengthening of the colon and its ligament, resulting in a vicious circle. (3) colonic redundancy often has colonic motor weakness, this is myogenic or neurogenic cause is not very clear, but tend to be more likely to neurogenic 4, diagnosis: the diagnosis of this disease is not difficult, as long as the following points are noted, you can determine the diagnosis: (1) abdominal pain, abdominal distension or long-term persistent constipation; some patients due to intestinal dysfunction, occasional diarrhea and constipation alternately. (2) X-ray barium enema is the main basis and important tool for the diagnosis of colonic redundancy. (3) Since colonic redundancy is prone to complications such as torsion, obstruction and perforation, when emergency surgery is performed, the corresponding segment of the colon can be found to be too long intraoperatively. (4) Since invasive examinations such as fiberoptic colonoscopy or sigmoidoscopy are difficult to perform, the colon is not functioning well, but has contractile or contracture changes, and is prone to perforation, and the length of the redundant colon cannot be clarified, the method of diagnosing redundant colon cannot be made. 5.Surgical treatment: Although there is colonic redundancy but no constipation, no surgical treatment is needed. For those who have long-term persistent constipation and non-surgical treatment is ineffective, surgical treatment is feasible. Indications for surgery: (1) long-term medical non-surgical treatment, the effect is not good, affecting work and life; (2) long-term persistent constipation, persistent abdominal distension, abdominal pain, stool cycle 4 to 9d; (3) barium enema shows that the colon is long, tortuous, coiled, repeatedly folded or the length of more than 35% to 40% of the normal length; (4) colon, especially the sigmoid colon is too long, prone to intestinal torsion, intussusception (4) The colon, especially the sigmoid colon, is too long and prone to complications such as intestinal torsion, intestinal obstruction, intestinal perforation, etc., and should be actively treated surgically. Removal of intestinal feces and cleansing of the intestine is a key measure for the success or failure of surgery. It can make the colon empty the feces and minimize the number of bacteria in the intestinal cavity, reduce the abdominal cavity and wound infection after surgery, and is one of the necessary conditions to prevent the occurrence of intestinal leakage. In principle, the site, scope and length of surgical resection should be different according to the type of colonic redundancy, but since there is no obvious boundary between redundant colon and normal colon, most scholars advocate an extended resection. type I: sigmoid colon, total sigmoid resection should be performed instead of partial sigmoid resection, the splenic flexure should be freed and a descending colorectal anastomosis should be performed; ascending colon is feasible The right hemicolectomy, free the hepatic flexure and perform transverse colonic ileostomy. Type II: for redundancy of descending colon and sigmoid colon, resection of descending colon and sigmoid colon is feasible, and the splenic flexure of transverse colon is freed downward and anastomosed with the upper end of rectum; right hemicolectomy and transverse colon are resected, and the splenic flexure is freed and ileocecal descending colon is anastomosed. Type III: resection of transverse colon, descending colon and sigmoid colon, freeing the hepatic flexure of the transverse colon and pulling it downward to anastomosis with the upper end of the rectum; total colon is redundant, total colon resection and anastomosis between the end of the ileum and the upper end of the rectum are feasible. Where combined with anterior rectal protrusion and circumferential hemorrhoids, intraoperative or then secondary surgical treatment.