Obstruction of the Small or Large Bowel, Paralytic Ileus and Pseudo-Obstruction

Essentials

• Acute mechanical intestinal obstruction should be identified and treated immediately. The treatment of imminent strangulation is particularly urgent (see also Acute abdomen in the adult Acute Abdomen in the Adult).
• In paralytic ileus, conservative treatment should be started early enough.
• Treat pseudo-obstruction of the colon by removing air or with neostigmine + glycopyrronium medication.
• Adhesive small bowel obstruction is common especially in patients with a history of abdominal surgery.
• Paralysis of the small intestine and colonic pseudo-obstruction are often associated with surgical treatment or other severe disease.
• It is essential to identify those at risk of intestinal perforation and requiring immediate treatment.

Aetiology

Symptoms and findings

• Abdominal pain may be constant or fluctuating.
  • Often mild and fluctuating at first, getting more severe and more constant.
• Vomiting; may be absent
• There may be bowel movements at first as the distal bowel empties but typically there are no bowel movements and no passing of air.
• If pain is not relieved by a functional nasogastric tube, intestinal ischaemia should be suspected.
  • The purpose of inserting a nasogastric tube is to alleviate nausea and vomiting and relieve intestinal distension to alleviate pain and to promote bowel movement.
• Any incarcerated hernia must be reduced without delay (see also Hernias in Adults).

Investigations

• Vital signs (blood pressure, heart rate, oxygen saturation, body temperature)
• Laboratory tests to check the patient's general condition
  • Basic blood count, CRP, sodium, potassium, creatinine, ALT, ALP, pancreas-specific plasma amylase, blood glucose, chemical screening of urine + bacterial culture of urine
  • To exclude symptoms of cardiac origin, ECG, TnT/TnI
• Abdominal CT is a basic investigation in patients with intestinal obstruction; further treatment should be chosen based on the findings and the patient's general condition.
  • CT will show the level and completeness of obstruction and often also the aetiology if it is other than an adhesion from preceding surgery.
• Small bowel follow-through examination, where the patient drinks a water-soluble contrast medium or is given this through a nasogastric tube, may trigger bowel movement. Entry of the contrast medium into the large bowel predicts successful conservative treatment.

Treatment

• If intestinal obstruction or ileus is suspected, the patient should be evaluated at an emergency unit with facilities for CT and, when necessary, for surgical treatment.
  • Gastrosurgical assessment or consultation is often necessary.
• Patients with a history of constipation can be treated at a primary health care unit or on an outpatient basis if they are pain-free and in good general condition.
• The urgency of treatment depends on the patient's general condition and imaging findings.
  • If a patient with small bowel obstruction becomes pain-free with the insertion of a nasogastric tube, conservative treatment can usually be tried at first. If the patient is in pain, strangulation should be suspected and further treatment arranged without delay.
  • In the case of large bowel obstruction, distended caecum and pain indicate a need for further measures.