Abdominal pain, vomiting, abdominal distension, constipation and cessation of exhaustion are typical symptoms of intestinal obstruction, but they are not uniform in severity in all types of intestinal obstruction.
(A) Abdominal pain Most patients with intestinal obstruction have abdominal pain. In patients with acute complete mechanical small bowel obstruction, abdominal pain is manifested as paroxysmal colic. It is caused by strong peristalsis of the intestine above the site of obstruction. It is mostly located in the middle of the abdomen. It often comes on suddenly. It gradually increases to a peak and lasts for several minutes before relieving. The interval can be completely painless, but can recur after a period of time. The degree of colic and the length of the interval period vary depending on the level of the obstruction and the severity of the disease. Generally speaking, in duodenal and upper jejunal obstruction, vomiting can play a role in decompression, and the patient’s colic is mild. Low ileal obstruction can inhibit intestinal peristalsis due to intestinal flatulence, so the colic pain is also mild. Only in acute jejunal obstruction, colic is more intense. Generally every 2 to 5 minutes is an attack. Incomplete intestinal obstruction has milder abdominal pain, which can be relieved after a bowel rumbling or exhaustion. The same is true for chronic intestinal obstruction, and the gap period is also long. In acute mechanical colonic obstruction, abdominal pain is mostly in the lower abdomen, which is generally milder than that of small bowel obstruction. If the function of ileocecal valve is normal, the contents of the colon cannot flow back to the small intestine, so the lumen of the intestine gradually expands and the pressure increases, so there may be persistent dull pain in addition to paroxysmal colic. Persistent dull pain in the interictal period is also the early manifestation of strangulated intestinal obstruction, and if ischemic necrosis has occurred in the intestinal wall, it will be persistent and severe abdominal pain. As for paralytic intestinal obstruction, since the intestinal muscle has no peristaltic ability, there is no colic attack, but persistent abdominal distension and pain can be caused by high intestinal distension.
(B) Vomiting Almost all patients with intestinal obstruction have vomiting, and the early stage is reflex vomiting, and the vomit is mostly stomach contents. In the later stage, the vomiting is reflux vomiting, which varies according to the height of the obstruction site. In low small bowel obstruction, vomiting is lighter and more sparse. In the case of colonic obstruction, there is no vomiting in the early stage because the ileocecal valve can stop the regurgitation, but in the late stage when the ileocecal valve is incompletely closed due to overfilling of the intestinal cavity, there is also more violent vomiting and the vomit may contain fecal juice.
(C) Abdominal distension is a late symptom, and its degree is related to the site of obstruction. In high small bowel obstruction, there is no obvious abdominal distension due to frequent vomiting; in the late stage of low small bowel obstruction or colonic obstruction, there is often significant full abdominal distension. In closed-collar obstruction, the distension of the intestinal segment is prominent and often shows asymmetric local distension. In paralytic intestinal obstruction, the entire intestinal canal is distended and enlarged, so the abdominal distension is significant.
(iv) Constipation and cessation of exhaustion In complete intestinal obstruction, the patient’s defecation and exhaustion disappear. However, in the first 2 to 3 days of high small bowel obstruction, if feces and gas accumulate in the intestinal cavity below the obstruction, there are still defecation and venting, so the existence of complete obstruction cannot be denied. Similarly, in strangulated intestinal obstruction, such as intestinal torsion, intestinal loop and intestinal obstruction caused by colon cancer, there can still be bloody stools or pus-blood stools.
(E) Systemic symptoms Patients with simple intestinal obstruction generally have no obvious systemic symptoms, but those with frequent vomiting and severe abdominal distension must be dehydrated. Those with low blood potassium have symptoms such as weakness, drowsiness, fatigue and cardiac arrhythmia. Patients with strangulated intestinal obstruction have the most significant systemic symptoms, with early debilitation and soon going into shock. In cases with abdominal infection, abdominal pain persists and spreads to the whole abdomen, along with manifestations of infection and toxemia such as chills, fever, and leukocytosis. The typical signs of intestinal obstruction are mainly in the abdomen.