Acute colonic pseudo-obstruction (ACPO) Acute colonic pseudo-obstruction is the presence of symptoms, signs and imaging manifestations of acute colonic obstruction in the absence of any mechanical cause of obstruction, which can easily lead to ischemia, necrosis and perforation of the large intestine and has a high mortality rate. it was first reported by Ogilvie in 1948, so it is called Ogilvie syndrome. It is also known as non-obstructive colonic dilatation, akinetic colonic obstruction and so on.
In recent years, there is an increasing trend of this disease, especially in the elderly. ACPO can be divided into primary and secondary according to its etiology, the former is only about 5%, the etiology is unclear; the latter is a complication of other diseases, about 56% occurs after surgery or trauma, mostly seen in the postoperative 3-6 d. According to the literature from 1948 to 1980, 88% is caused by causes other than colon, such as surgery, trauma, heart failure, uremia, diabetes, ischemic enterocolitis, metastatic tumor Hypoxia and hypotension, etc.; 12% have unknown causes.
The disease is associated with sacral parasympathetic nerve dysfunction, partial nerve conduction dysfunction, reduced number of ganglion cells in the intestinal wall and degenerative nerve cells seen microscopically. The pathogenesis of the disease is mainly surgical, and the histological examination of the intestinal wall of ACPO patients generally has no obvious pathological changes.
ACPO, like the development of mechanical obstruction of the distal colon, will eventually lead to colonic necrosis or perforation if not actively treated, commonly in the right colon and cecum. The process of its occurrence and development first shows longitudinal splitting of the plasma membrane, followed by tearing of the internal and external muscular layers, which may form a mucosal hernia and finally mucosal rupture and perforation. The occurrence of intestinal perforation is related to the amount of pressure acting on the intestinal wall, and the incidence of perforation increases significantly as the diameter of the cecum increases.
It often develops during hospitalization, usually in association with other systemic diseases, postoperative or trauma, and is more common in elderly people, more men than women. The main manifestations are abdominal cramps with progressive abdominal distension, reduced defecation or constipation; other manifestations include nausea, vomiting, anorexia, etc. Fever is more common in those with intestinal ischemia or perforation. Signs are obvious abdominal distension, visible colonic bowel pattern, and mild tenderness; bowel sounds are variable, can be normal, reduced or obstructive, but rarely disappear, and air over water sound is rare. Due to progressive worsening of colonic dilatation, diffuse peritonitis may develop as a result of cecum perforation. Patients may present with severe abdominal pain, fever, and signs of peritoneal irritation. Early appendiceal perforation should be suspected if tenderness in the right iliac fossa is obvious.
(a) The symptoms and signs of intestinal obstruction are prolonged but relatively mild and do not worsen sharply with recurrent disease;
(b) Abdominal distension is relatively mild, the general intestinal pattern is not obvious, abdominal pressure pain can be extensive but mild, and bowel sounds are weak, rarely hyperactive or absent;
(C) abdominal X-ray plain film can be seen in a certain intestinal segment with obvious pneumatization, but lack of increasingly heavy performance;
(d) Although the intestinal obstruction is long, the small intestine is dilated obviously, but there is often gas and feces in the colon. Anyone with the above characteristics should not be operated hastily, but should be carefully examined and closely observed, and a clear diagnosis can usually be made. The diagnosis can often be made based on clinical symptoms and signs, combined with abdominal X-ray examination. The key is that mechanical colonic obstruction must be excluded, because the treatment measures for both are very different.
ACPO is very similar to cecum or sigmoid torsion in terms of clinical presentation and even imaging, and should be differentiated. In addition, ACPO needs to be differentiated from intestinal obstruction due to hernia, intestinal adhesions and ischemic colitis, acute gastric dilatation, and paralytic obstruction of the small intestine. For acute colonic pseudo-obstruction, conservative treatment, such as gastrointestinal decompression, correction of water-electrolyte imbalance, anti-infection and anal venting, etc., was mostly used in the past. In recent years, many authors at home and abroad have reported the successful treatment of this disease with fiberoptic colonoscopy.
Others believe that fiberoptic colonoscopy is also feasible without intestinal preparation, and it is only necessary to use 1L water enema 1h before the examination to flush out the fecal residue, with as little inflation as possible during the examination, and not to insert the tube blindly. If intestinal mucosa ischemia or bleeding is found during the examination, the examination should be stopped and replaced by surgery to avoid perforation. Indications for surgery of acute pseudocolonic obstruction.
①Signs of intestinal wall necrosis and peritonitis;
②The cecum diameter >9cm or 12cm is prone to perforation;
③Failure of conservative treatment;
④Severe respiratory distress;
⑤ Those with doubtful diagnosis. There is a direct relationship between cecum diameter and the timing of colonic decompression and death.
Some data show that the incidence of necrosis and perforation reaches 23% and the morbidity and mortality rate is 14% when the diameter of the cecum is >14cm; while the necrosis, perforation and morbidity and mortality rate are 7% when the diameter is 14cm. The morbidity and mortality rate of colon decompression performed more than 7 d after the onset of disease was 5 times higher than that of those operated within 4 d after the onset of disease. When the colon is necrotic or perforated and emergency surgery is performed, the morbidity and mortality rate is as high as 10% to 50%. Therefore, early diagnosis and timely decompression can reduce the morbidity and mortality rate.
Pham studied the abdominal X-ray changes of the cecum in 24 cases of ACPO after decompression by fiberoptic colonoscopy, and the size of the cecum was only reduced by about 2 cm from 4 to 24 h after decompression, which is not as good as expected, which is noteworthy. ACPO recovers within 3-6 d with appropriate treatment, but elderly patients or those with severe underlying disease have a poor prognosis, and even if satisfactory colonic decompression has been performed, the morbidity and mortality rate is still high. the mortality rate for non-operative treatment of ACPO is 14% and for operative treatment is 30%, while the operative mortality rate for cecum intubation and decompression is 15%, similar to that of conservative treatment.
The patient’s age, the presence or absence of cecum ischemia or perforation, and the timeliness of colonic decompression all have a significant impact on the prognosis. The incidence of cecum perforation has been reported to be 14% to 40%, and if perforation occurs, the morbidity and mortality rate can be 40% to 50%. Therefore, all risk factors, except age, should be controlled in a timely manner.