Congenital megacolon
Hirschsprung’s disease, a functional intestinal obstruction caused by peristaltic dysfunction of the ganglionless intestine, is the second most common congenital malformation of the gastrointestinal tract, with an incidence of 1 case per 5,000 live births and a male to female ratio of approximately 4:1.
There are several theories as to the cause of congenital megacolon. Most believe that the intermuscular plexus is formed by neuroblasts of the neural crest, which begin to migrate cephalad to caudal along the vagal trunk in the fifth week of embryonic life and reach the distal part of the digestive tract in the twelfth week. The absence of ganglion cells in the intestinal wall can be caused if the neuroblast migration is halted due to viral infection, metabolic disorders, genetic or environmental factors. The earlier the pause, the higher the site of the lesion. Since the rectum and sigmoid colon are located at the most distal part of the GI tract, they have the highest chance of being involved. Many other scholars believe that the lack of ganglion cells may be related to insufficient blood supply to the intestine during fetal life or the action of certain toxins.
Pathophysiology
The motor mechanism of the colonic and rectal internal sphincter is very complex and is mainly innervated by 3 types of nerves: 1) exogenous nerves: both vagus and sympathetic nerves. The vagus nerve is derived from the visceral branch of the right vagus nerve and the sacral parasympathetic nerve, which are distributed in the upper rectum and the left colon. The sympathetic nerve comes from the superior mesenteric plexus of the thoracolumbar plexus, and its postganglionic fibers follow the superior mesenteric artery to the small Robe÷’right colon. The sympathetic nerves of the left colon and rectum come from the inferior mesenteric plexus of the lumbar sympathetic, and the sympathetic nerves innervating the internal sphincter come from the rectal plexus of the inferior abdominal plexus. The motor parasympathetic nerves that innervate the intestinal wall act as excitatory (contraction) and sympathetic nerves act as inhibitory (diastole). However, the opposite is true for the endorectal sphincter, where sympathetic nerves act as contractile activity and parasympathetic nerves act as inhibition. ②Endogenous nerves: including two kinds of excitatory nerves, cholinergic and non-cholinergic, which can play a contractile role, and two kinds of nerves, adrenergic and non-adrenergic, which can play an inhibitory role. (iii) Purinergic nerves: Purinergic nerves are powerful inhibitory systems within the intestinal wall. It is thought that the lack of peristalsis in the narrow segment of congenital megacolon may be due to a deficiency of purinergic ganglion cells.
The pathology of congenital megacolon is characterized by the lack or absence of ganglion cells in the stenotic segment of the intestine, thus leading to spastic stenosis of the diseased intestinal canal and internal sphincter, lack of normal intestinal peristaltic function, and formation of functional intestinal obstruction. The parasympathetic preganglionic fibers, which should establish synaptic connections with ganglion cells, proliferate and thicken in the ganglion cell-free intestinal segment, and the sympathetic postganglionic fibers increase significantly. The massive release of acetylcholine is thought to be one of the main causes of intestinal spasm, and the lack of cholinergic ganglion cells blocks normal segmental motility and rhythmic propulsive peristalsis. The parasympathetic nerves from the sacral region, in turn, act directly on the muscle cells of the intestinal wall, thus producing a persistent tonic contraction of the diseased intestinal canal. As the internal sphincter and the diseased intestinal segment remain contracted for a long time, the normal propulsion of intestinal contents is blocked, resulting in abdominal distension and difficulty in fecal expulsion.
Pathological changes of congenital megacolon are evident in gross specimens, namely the stenotic segment, the migrated region and the dilated segment. The stenotic segment is located at the distal end of the dilated segment, usually 7-250 px from the anus below the rectosigmoid junction, and the diameter of the stenotic segment is very different from that of the dilated segment, but there is no difference in surface structure.
1, ganglion cell absence The ganglion cells in the intermuscular plexus and submucosal plexus of the stenotic segment are absent, and it is difficult to find the plexus at the distal end of the stenotic intestine. The nerve fibers were thickened. The number of nerve fibers increases and they are arranged in a neat wavy pattern. Sometimes individual ganglion cells could be found, but the morphology was abnormal. The normal nerve plexus and ganglion cells were gradually found in the proximal colonic wall of the stenotic segment.
Histochemical examination of the submucosa and intermucosa of the stenotic segment of the intestine showed different numbers of acetylcholinesterase positive parasympathetic nerve fibers with enhanced enzyme activity, usually the most abundant branches in the intermucosa and near the mucosal muscle, while the proximal end of the enlarged colon and the normal colon were negative.
3, cholinergic nerve hyperplasia electron microscopy in the stenotic segment, the number of granular vesicles (parasympathetic preganglionic fibers) can be seen more than in the dilated segment, which further proves the cholinergic nerve hyperplasia in the stenotic segment without ganglion cells. No large dark vesicle-dominated expansions were seen in the intestinal wall of the stenotic segment, which are vesicles specific to the terminal end of the purinergic nerve that produces a strong relaxing effect on smooth muscle. The lack of such vesicles in the stenotic segment means that the relaxing effect of the intestinal wall is lost.
4, Fluorescence microscopy of the strongly fluorescent adrenergic nerve fibers at the intermuscular plexus of the stenotic segment, and the disappearance of the bamboo basket-like structures formed around the ganglion cells. The normal arrangement of adrenergic nerve (sympathetic nerve) fibers had been destroyed and replaced by a disorganized number of nerve fibers, and the nerve fibers were thickened in a bundle shape. The amount of norepinephrine in the wall of the lesioned intestine in the stenotic segment is approximately three times higher than normal.
According to the degree of extension of nerve ganglion cells in the intestinal wall of the lesion, the clinical extent of the stenotic segment can be divided into 5 types.
The short segment type lesion is located in the distal part of the rectum, not more than 6.125 px from the anus, accounting for about 10%.
2.The common type without ganglion cell area starts from the anus up to the sigmoid colon area, about 225px from the anus, accounting for about 75%.
3.Long segment type lesions extend to the sigmoid colon or descending colon, accounting for about 10%.
4.Whole colon type lesions spread to the whole colon and the end of the ileum, not more than 750px from the ileocecal valve, accounting for about 5%.
5.Whole intestine lesions involving all the colon and the end of the ileum more than 750px are rare.
Clinical manifestations
1.No meconium or delayed meconium discharge within 36 hours after birth, no meconium discharge or very little discharge. Due to the accumulation of meconium in the colon, symptoms of low-level intestinal obstruction with abdominal distension and vomiting appear to varying degrees. After lavage or other treatment, the feces can be excreted and the obstructive symptoms can be reduced or disappeared. If the treatment is inappropriate, the obstructive symptoms will recur after the number, and eventually emergency enterostomy will be required due to the aggravation of intestinal obstruction or severe dehydration.
The degree of abdominal distension is related to the effectiveness of the treatment method, the length of the pathology and the extent of the lesion. Most of the children were born with gradual abdominal distension, frog-shaped abdomen, early protrusion to the sides and then the whole abdomen distension. The abdominal circumference is significantly larger than the chest circumference. Untreated or improperly treated children, abdominal distension is progressively aggravated, a large amount of long-term intestinal contents and gas retained in the colon, the intestinal cavity can form a huge fecal stone, and can be transformed into a complete low intestinal obstruction.
3.The general condition of the sick child has poor appetite, due to long-term malnutrition, manifested as delayed development, anemia, wasting, low resistance and hypoproteinemia.
4.Rectal anorectal finger examination can reveal the tightness of the internal sphincter, and there can be a feeling of emptiness in the rectal jug abdomen. If the narrow section is short, sometimes a fecal mass can be palpated. When the finger is withdrawn from the anal canal, it is often accompanied by gas and loose stool discharge.
5, complications of small bowel colitis, is one of the most serious complications of congenital megacolon, mostly occurs in infants under 3 months of age, is the most important cause of death. Due to spastic stenosis and lack of normal peristaltic function of the ganglion cell-free intestinal segment, it leads to long-term retention of feces in the colon, proliferation of bacteria, damage to the intestinal wall by bacterial toxins, and leakage of large amounts of fluid due to increased vascular permeability of the intestinal wall. The clinical manifestations are sudden change from frequent constipation to severe diarrhea, excretion of large amount of foul-smelling watery stool, accompanied by high fever, severe dehydration and toxic symptoms such as electrolyte disorders, abdominal distension, hypoproteinemia, and rapid deterioration of general condition.
Diagnosis
Any newborn with abnormal meconium excretion since birth, accompanied by abdominal distension and recurrent constipation, a wrapping sensation in the anus and a feeling of emptiness in the rectal jug abdomen on rectal-anal finger examination, and a large amount of gas excretion with finger withdrawal, and temporary relief of abdominal distension symptoms, should be considered as congenital megacolon. In older children, in addition to persistent constipation, there is also severe abdominal distension, and symptoms of low-level intestinal obstruction such as intestinal pattern and intestinal peristaltic waves can be seen, and they gradually worsen. For children suspected of having congenital megacolon, the following further tests should be performed to help confirm the diagnosis.
1.X-ray examination The upright X-ray plain examination of abdomen is a routine examination item for the diagnosis of neonatal intestinal obstruction, attention should be paid to the degree and location of intestinal curvature inflation and dilatation, and sometimes it is difficult to diagnose by X-ray film alone. Barium enema examination is a valuable method to diagnose congenital megacolon. Precautions for barium enema examination include: ① no bowel cleansing before barium enema; ② barium injection anal catheter should be used and should not be inserted too deeply; ③ the pressure should not be too high when injecting barium, and should be injected slowly; ④ it is better to take lateral film when taking pictures, because the upper end of rectum is tilted backward when taking orthopantomographs, and the images overlap, and it is not accurate enough to understand the length of narrow segment of intestine and the distance from the anus; ④ if there is difficulty in confirming the diagnosis in difficult cases If it is difficult to confirm the diagnosis, the fluoroscopy should be repeated after 24 hours, if there is still barium in the colon, it will help the diagnosis. In a typical barium enema fluoroscopy, it can be seen that there is no normal peristalsis in the intestinal wall of congenital megacolon, the intestinal mucosa is smooth, the intestinal tube is like a tube, and the tube is straight and tension-free, and there are dilated, migrated and narrow intestinal tube, which can be used to confirm the diagnosis. Barium enema diagnosis of congenital megacolon, the accuracy rate of about 80%.
2, rectal anorectal manometry using three balloon devices and electrical pressure measurement, respectively, placed in the external sphincter, internal sphincter and rectal jug abdomen level, to observe the resting pressure changes in these areas and the relaxation reflex of the internal sphincter. In normal children, rectal dilatation is sufficient to produce reflex relaxation of the internal sphincter, and the pressure of the internal sphincter decreases with it. In children with congenital macrosomia, the sphincter does not relax, but is significantly contracted and the pressure is increased. This test must be performed 12 days after birth to be diagnostic. If necessary, the pressure of the rectal canal can be repeatedly measured.
3, rectal biopsy in the rectal wall under anesthesia cut a rectal wall of the whole layer of tissue, in the dentate line 50px above the cut tissue, section examination to ensure the presence of ganglion cells, can be diagnosed as congenital megacolon. Sometimes misdiagnosis may occur due to superficial sectioning. This test can cause intestinal perforation, infection, etc., has been less used.
4, enzymatic examination of rectal mucosa histochemical examination, high diagnostic accuracy and safer. Commonly used enzymatic examination methods are three: ① acetylcholinesterase qualitative examination: rectal mucosa after bowel cleansing, according to the requirements of the treatment under the microscope, the normal intestinal mucosa acetylcholinesterase reaction negative, that is, no parasympathetic nerve fibers, congenital megacolon disease children, can see the narrow section of intestinal mucosa appear acetylcholinesterase positive parasympathetic nerve fibers, according to its number, thickness can be judged as (+) to (XXX), most people think that the correct diagnosis rate is more than 96%, and no false positive results are seen; ② quantitative determination of cholinesterase activity; ③ determination of erythrocyte acetylcholinesterase activity.
5, electromyography examination electromyography examination records the bioelectric recording graphic of intestinal wall activity, and the diagnosis is achieved through the analysis of bioelectric waveform. The waveform of the intestinal segment without ganglion cell disease shows slow waves low and smooth, with few and irregular occurrences and lack of peak-shaped waves. Its diagnostic accuracy is up to 84% and can be repeated if necessary. ‘
Differential diagnosis
1, congenital colonic atresia and stenosis is less common clinically. The symptoms of low intestinal obstruction appear after birth, and there is no large amount of fecal discharge on rectal-anal finger examination or enema, but only a small amount of grayish-white secretion. Barium enema fluoroscopy, can be seen in the distal colon is small, stunted, barium forward obstruction, cecum parts can be expanded, the intestinal cavity inflated.
2, neonatal constipation fetal feces sticky, difficult to discharge, manifested as symptoms of intestinal obstruction. After enema with warm saline or j% hydrogen peroxide solution, the abnormal viscous fecal accumulation is discharged, and the obstruction symptoms can be eliminated.
3, neonatal peritonitis has the characteristics of paralytic intestinal obstruction, with fever, abdominal distension, vomiting and other symptoms. The cause of pathogenesis can often be found, such as pneumonia, umbilical infection, sepsis and other parts of infectious diseases.
4. Children with abnormal ganglion cell development have cool symptoms like congenital megacolon after birth, and most of them show symptoms of low-level intestinal obstruction such as abdominal distension and vomiting. The correct diagnosis can only be made on biopsy, and histological examination reveals immature ganglion cells smaller than normal or isolated ganglion cytopenias.
5, Idiopathic megacolon is most often seen in older children with normal expulsion of meconium after birth, resulting in long-term intractable bad constipation due to some as yet unspecified cause. The biopsy of the rectal wall of the sick child can find normal ganglion cells, but the pressure threshold (i.e., the amount of air injected into the rectal balloon) that causes defecation awareness is almost l times higher than normal. The clinical characteristics of idiopathic megacolon are normal diet, abdominal distension is not significant, the rectum is significantly enlarged, but there is no stenosis, rectal anorectal examination can be palpated huge fecal stone, rectal biopsy or histochemical examination, can be concluded correctly.
6, secondary minister colon Mostly secondary to congenital rectoanal malformations, such as rectal navicular fistula, anal stenosis, congenital anal atresia postoperative stenosis and other causes of defecation, can be secondary to megacolon. Children with secondary megacolon have normal ganglion cells on rectal biopsy, but with congenital malformation of rectum and anus and history of surgery, the diagnosis is not difficult when combined with other tests.
Treatment
Non-surgical treatment: The purpose of non-surgical treatment is to achieve one bowel movement per day or every other day by various methods to relieve low-level intestinal obstruction so that the child can pass through the neonatal period, and then perform radical surgery if necessary. It is suitable for younger children or children with other serious congenital anomalies, and can also maintain bowel function and achieve the goal of food and nutrient absorption, and prepare for radical surgery. However, because children with congenital megacolon have difficult defecation and stubborn symptoms, a single approach may soon fail and affect the outcome of treatment. Therefore, it is often necessary to use a variety of methods alternately or in combination.
1, oral lubricants or laxatives such as oral honey, sesame oil, liquid paraffin oil, fruit guide tablets, rhubarb, etc., to maintain daily bowel movements. The amount of medication can be increased or decreased as appropriate according to the nature and frequency of fecal discharge.
2, anal plugging with open plug or glycerin suppositories, daily or every other day, can assist the sick child defecation.
3.Choose a suitable enema, gently place it into the anus and slowly send it into the rectum without resistance, the head end should exceed the narrow part, do not operate with violence. Rectosigmoid junction curved to the left, such as the insertion of excessive force can lead to intestinal perforation. Especially in neonatal enema, because the intestinal wall is thin and short, careless operation is more likely to lead to intestinal perforation. Isotonic warm saline must be used to wash the intestine, generally salt can be divided into 4.25gl packets, when preparing the salt can be placed in 500ml of water 1 packet. Repeated irrigation, each injection and outflow should be basically equal, while gently massage the abdomen to help expel feces. Therefore, irrigation inch must pay attention to record the amount of saline and the amount of discharge, if the injection of saline can not be all discharged, you need to inject }r oil at the same time, wait for the stool to soften and then irrigate again. If the abdominal distension does not improve after the enema, the enema anal tube should be retained.
4.Dilation of the anus through rectal-anal finger diagnosis can relax the anal sphincter and achieve the purpose of assisting defecation. For short-segment congenital megacolon with mild symptoms, sometimes it can be cured by long-term anal dilation, which can avoid the pain of surgery.
Surgical treatment: colostomy is recommended for those with severe colitis or other serious congenital malformations, as well as those whose symptoms of intestinal obstruction cannot be relieved by non-surgical methods such as enema. Postoperative infection control and intensive supportive therapy should be provided, and radical surgery should be performed after 6 months of improvement in the general condition of the child. Most advocate a stoma in the normal segment of the sigmoid ganglion cells or a transverse colostomy. A sigmoid stoma preserves the greatest extent of colonic resorption and allows closure of the fistula with radical surgery in one visit during the second radical surgery. However, transverse colostomy is preferable for long-segment megacolon, which should be located close to the hepatic flexure to avoid damage to the splenic flexure and not affect the length of the loosened down prolapsed colon during radical surgery. No matter where the stoma is made, the fistula site must have normal ganglion cells, otherwise the bowel cannot be defecated after the stoma and the symptoms of intestinal obstruction cannot be relieved.
Radical surgery can be performed when the child is in good general condition, and when there is not much fecal accumulation in the dilated colon, after proper preoperative preparation. In recent years, it is advocated to perform one-stage radical surgery in neonates, because the younger the lesion is, the more limited it is, and the effect after radical surgery is good, and complications such as congenital megacolon crisis can be avoided before surgery.
In order to improve the results of congenital megacolon radical surgery, reduce mortality and complications, many scholars have continuously improved the surgical methods, and there are nearly 20 improved surgical procedures so far. The main differences of various surgical procedures are as follows: (1) the shape and number of bowel tubes without ganglion cells should be preserved, and the downward prolapsed colon should be of sufficient length and should not be under tension; (2) the extent of resection of rectum, anal canal and internal sphincter should be cut at 0.125px above the dentate line, and the posterior wall of rectum should be cut at 0.125px above the dentate line, which is too high for postoperative constipation and too low for incontinence; (3) whether the pelvic cavity should be separated, and the separation should be minimized during surgery to reduce the area of the pelvic nerves. area to reduce the damage to the pelvic nerves; ④ whether the newly constructed rectoanal canal has a blind pocket or gate, and rectal clamp, improperly placed; ⑤ whether postoperative anal dilation or auxiliary addition of other surgeries is required. There are seven widely used surgical procedures, and although each has its own characteristics and complications are different, the long-term efficacy is similar. It is generally believed that the effectiveness of the procedure is determined not by the surgical approach, but by the operator’s proficiency in the procedure. The other procedures are also developed on the basis of the first four procedures described below.
1.Drag-out rectosigmoidectomy (Swenson procedure)
Indications: short segment type, common type, long segment type congenital megacolon.
2.Colonic resection through the rectum after the colon drag out (Duhamel operation)
Indications: short-segment, common and long-segment congenital megacolon.
3.rectal mucosal stripping intrathecal colectomy (Soave operation)
Indications: short segment type, common type, long segment type and total colon type congenital megacolon.
4.Transabdominal colorectal resection with end-to-end anastomosis (Rehbein operation)
Indications: short segment type, common type, long segment type congenital megacolon.
5.Posterior rectal wall internal sphincter resection (Thomas operation)
Indications: Short-segment congenital megacolon in newborns and small infants.
6.Lateral ileocolic anastomosis (Martin’s operation)
Indications: Total colon type congenital megacolon.
Precautions to be taken during surgery
1.Judgment of the site and length of the resected intestinal canal After opening the abdomen, the degree and length of the stenotic intestinal segment, the degree and location of the dilated intestinal segment and the migrated intestinal segment should be explored. At the junction between the proximal end of the thick intestinal canal and the normal intestinal canal, take 0.5×0.125 px of the whole intestinal wall tissue for rapid section biopsy to clarify whether the ganglion cells are normal here. A silk suture was sewn in this plane as a marker, i.e., the boundary between the proposed preservation and resection of the intestinal canal. It is very important to decide this standard point, which is directly related to the quality of preserved intestine and the recovery of intestinal function and the outcome of the operation. The following characteristics are observed visually: (1) the diameter of the intestinal canal is close to the normal intestinal canal; (2) the intestinal wall is soft, thin and red; (3) the colonic wall is not thickened and leathery, there is no widening and splitting of the colonic band, and the intestinal peristaltic function is good. Most people advocate routine freeing of splenic colonic ligament and left transverse colon, and removing as much enlarged colon as possible to ensure good nerve and peristaltic function of the dragged down colon and prevent dragging out the hypertrophic intestinal tube whose nerves have been degenerated from the anastomosis, leading to recurrence of constipation after surgery.
2, to prevent abdominal cavity pollution in the abdominal cavity resection of enlarged intestinal segment or intestinal anastomosis in the pelvis, easily lead to abdominal cavity pollution and postoperative abdominal cavity infection. In addition to preoperative clean bowel washing and antibiotic retention enema and other intestinal preparation, intraoperative operation is extremely important. When disconnecting the intestinal tube, the proximal and distal intestinal tubes should be thoroughly disinfected, and attention should be paid to protecting the surrounding tissues to avoid contamination of the abdominal cavity. The intestinal contents often leak because of poor proximal colonic clamping or retention of the anastomosis wall is too short, and moving the clamps several times during anastomosis can also make the intestinal contents leak. The intestinal clamp should not be loosened frequently during the anastomosis, and the anastomosed intestinal wall should be sterilized strictly as required. The most fundamental measure to avoid intra-abdominal contamination and infection is not to cut the intestinal tube and anastomosis in the abdominal cavity. Once the intraoperative abdominal cavity is contaminated, the contaminated area and its surroundings should be thoroughly flushed before closing the abdominal cavity, and abdominal drainage can also be placed.
3, avoid damage to the ureter The ureter enters the bladder through both sides of the rectum, the right side is slightly far from the rectal wall, the left side is closer, through the peritoneum can clearly see the ureter towards. The operator should cut the peritoneum close to the rectum and separate it along the rectal wall. The ureter should be pulled apart and protected, and the ureter may not be exposed during surgery because it is not only time-consuming, but also easy to damage the ureter. Once damaged, hematuria or ureteral leakage can occur after surgery.
In order to prevent postoperative urinary retention, the posterior and bilateral separation of the rectum should be minimized during surgery to reduce the damage to the perirectal tissues and nerves. The posterior rectal space is loose connective tissue, which is pushed away from the rectum to the dentate line, and the lateral rectal ligament should only be separated and cut off in the upper l/3, so too much freeing is likely to cause bleeding and injury to the pelvic nerves. The pelvis of older children is deeper, finger separation is difficult to reach the dentate line, long curved vascular forceps can be used to clip the gauze ball down to the dentate line, otherwise it affects the extra-anal colon and rectal anastomosis. A small amount of pelvic bleeding can be filled with dry gauze to stop the bleeding, and check again whether the bleeding stops when the abdomen is closed to prevent infection or hemorrhagic shock after pelvic blood accumulation.
5.The mesenteric vascular arch should not be stretched too tightly. The ganglion cells in the intestinal wall are very sensitive to hypoxia, and intraoperative compression, straining and vasospasm lead to transient insufficiency of blood supply to the intestinal wall tissue, which can lead to degeneration of ganglion cells in the intestinal wall and recurrence of constipation symptoms after surgery. Insufficient mesenteric release often affects the length of intestinal collaterals, and the operator often releases the mesentery to the edge of the vascular arch, and when pulling the colon downward, excessive force may result in excessive vascular tension or even tearing. Note that when pulling down the colon during surgery, do not put the main supply vessels in tension, if not careful during surgery, it can not only lead to vascular injury or insufficient blood supply to the intestinal wall, but also make the anastomosis too much tension and affect the healing of the anastomosis. ‘ ,
Postoperative complications and treatment
1, urinary retention Mostly due to injury to the pelvic nerve during extensive separation of the pelvis, resulting in weakness of bladder contraction after surgery. The main method to prevent this complication is to reduce the injury to the pelvic nerve, to separate it close to the rectal wall, and to reduce the squeezing and pulling of the pulling hook to both sides during surgery. Once urinary retention occurs, a straight catheter should be left in place, open clamping at regular intervals, and adjuvant therapeutic measures such as acupuncture and physiotherapy should be taken, which mostly heal within 3 to 5 days, with a few lasting longer.
2, anastomotic leakage is mostly caused by pelvic infection, inadequate blood supply to the colon, retraction tear due to excessive anastomotic tension, etc. Pelvic contamination, blood pooling, improper use of antibiotics, etc. can lead to pelvic infection, anastomosis immersed in pus, which eventually causes anastomotic splitting. To prevent this, first of all, intra-abdominal incision or anastomosis of the bowel should be avoided whenever possible. Colonic freeing should be of sufficient length and should be performed gently to ensure adequate blood supply to the intestinal wall. When placing the clamps, do not close to the closed blind end to avoid excessive tension or tightening during clamping and premature declamping. The pelvic cavity should be repeatedly flushed before closing the abdomen, and a drainage tube should be placed after intraoperative contamination flushing. Postoperatively, effective antibiotics should be given appropriately, especially to enhance the management of anaerobic bacteria. If anastomotic leak occurs, the child mostly presents with abdominal distension, high fever, stopping defecation, and pressure and muscle tension in the lower abdomen on abdominal examination within 4 to 8 days after surgery. After anastomotic leak is found, enterostomy should be performed immediately to save the life of the child.
3, feces and incontinence are mainly due to excessive removal of the internal sphincter or injury to other sphincter groups during surgery. In mild cases, the feces is foul, and in severe cases, the incontinence is more severe at night or when eating and drinking are not appropriate. The incidence of fecal soiling is 20-30% and incontinence is 11-17%. In order to prevent this complication, most people believe that the anastomosis line of the posterior rectal wall should be about 1.0 from the dentate line, and more of the internal sphincter should be preserved. Individual cases may have recurrence of internal sphincter spasm and constipation symptoms after surgery due to retaining too much internal sphincter, but it is far easier to treat than anal incontinence and fecal soiling.
4. Constipation and recurrence of obstructive symptoms are mainly due to insufficient resection of the proximal diseased bowel or excessive preservation of the rectum without ganglion cells, as well as postoperative anastomotic stenosis. In order to prevent the recurrence of constipation and obstruction symptoms after surgery, in addition to visual observation to determine the boundary between resected and preserved intestine, it is best to take the intestinal wall tissue for rapid sectioning to determine whether the ganglion cells of the preserved colon segment are normal. Sometimes, although the ganglion cells are normal on pathological examination, individual cases may have postoperative constipation or recurrence of obstruction symptoms, mainly due to temporary ischemia of the preserved intestine secondary to neurodegeneration caused by injury during surgery. Therefore, the separation of the colon requires gentle operation to ensure adequate blood circulation in the intestinal canal, and the tension should not be too great when pulling down the colon.
5, blind pockets and gates The formation of the rectal colonic septum clamped too low. The septum forms a blind bag before the rectum, the septum itself down to form a gate, the anal contraction of feces forward into the blind bag, a large fecal stone formed in the blind bag for a long time. Forward pressure on the bladder, resulting in frequent urination, backward pressure on the colon causes intestinal obstruction. The gate prolapses and affects the sphincter contraction leading to fecal soiling. In this case, it is necessary to re-clamp and remove the rectocolonic septum in order to keep the bowel movement open.