Colonic obstruction is a group of acute conditions that require early identification and aggressive intervention. The causes vary according to age and are classified as mechanical obstruction, and dynamic obstruction (pseudo-obstruction). In middle-aged and elderly patients, the main causes include tumors, inflammatory lesions (diverticulitis), strictures, and fecal impaction or torsion. In neonates, the main causes are due to abnormal anal development or other anatomical abnormalities and meconium.
Etiology
1.Cancerous obstruction
It is the primary cause of colonic obstruction.
2.Colonic torsion
It is the second most common cause and can occur in the cecum, transverse colon and sigmoid colon, but the sigmoid colon is the most common.
3.Colonic schistosomiasis
In China’s schistosomiasis endemic areas, schistosome granuloma or associated colon cancer is still common.
4.Acute pseudocolonic obstruction (Ogilvie syndrome)
Fariano believes that this disease is related to sacral parasympathetic nerve dysfunction, and Matsui reports that partial nerve conduction dysfunction leads to this disease, and the number of ganglion cells in the intestinal wall is reduced and the nerve cells have degenerative changes under the microscope.
5.Pelvic postoperative adhesions leading to colonic obstruction
This disease is characterized by: (1) mostly occurring in middle-aged women after pelvic surgery; (2) intermittent abdominal distension, chronic abdominal pain and constipation; (3) no specific lesions in barium enema; (4) sigmoid colon is seen at an angle on fiber colonoscopy, and there is also stenosis, preventing the entry of colonoscope.
6.Obstruction caused by extra-colonic tumor compression or invasion
Such as pancreatic cancer or gastric cancer invading the transverse colon and causing obstruction; female pelvic tumor, especially ovarian tumor compression of the sigmoid colon causing obstruction is not uncommon.
7.Gallstone obstruction
It accounts for 1% to 3% of all intestinal obstruction, and the preoperative diagnosis rate is only about 15%.
Pathogenesis
When the colon is obstructed, because the ileocecal valve is closed, the intestinal contents can only enter but not exit, forming a closed-collar type of intestinal obstruction. The bacterial content in the colon is high, and after obstruction, bacterial reproduction is accelerated, which can easily lead to systemic infection and even toxic shock. The severity of cancerous obstruction depends on the degree of tumor invasion. In case of incomplete obstruction, the clinical manifestations and pathophysiological changes are not serious, but in case of complete obstruction, there is severe intestinal distension, and excessive intestinal distension thins the intestinal wall and reduces blood supply, so it is easy to necrosis and perforation.
Examination
1.Imaging examination
Abdominal X-ray plain film, CT, MRI and other examinations can help to clarify the site of obstruction and its cause.
2.Blood examination
Blood routine and blood biochemical examination can help to understand whether it is strangulated obstruction and whether there are water and electrolyte disorders.
3.Colonoscopy
It helps to clarify the nature of the lesion (tumor can be found and biopsy can be taken for pathological diagnosis).
Diagnosis
The clinical manifestations of colonic obstruction are basically similar to those of general small bowel obstruction, and the clinical manifestations have the following characteristics.
1. all patients have abdominal pain, the right half of the colonic obstruction is mostly located in the right upper abdomen, the left half is mostly located in the left lower abdomen, the abdominal pain of chronic obstruction is mild, the abdominal pain of acute obstruction is severe, but not as severe as intestinal torsion and intestinal overlap
2, nausea and vomiting appear late, or even absent. Later vomit is yellow fecal-like contents with foul odor.
3, abdominal distension is more obvious than small bowel obstruction, with protrusion of the abdomen on both sides, sometimes in the shape of a horseshoe.
4, anal cessation of defecation and venting, but most patients can still have a small amount of gas expelled in the early stage of obstruction.
5, physical examination sees obvious abdominal distension, which may show a horseshoe shape, drum sound on percussion, and the sound of gas over water on auscultation.
6, X-ray plain film examination can be seen in the colon obvious fluid, gas, and liquid plane.
Treatment
1.Surgical treatment
Under the premise of excluding pseudo-intestinal obstruction, actively carry out surgical investigation.
2.Medical treatment
The main treatment is symptomatic treatment, correction of water-electrolyte imbalance, gastrointestinal decompression, anti-infection and promotion of anal canal exhaust, etc. If mechanical obstruction is excluded, it should be treated according to dynamic intestinal obstruction.
Prevention
Regular screening of colorectal tumors in middle-aged and elderly people, early detection of tumor disease for intervention and treatment is the most effective way to prevent cancerous obstruction.