The small bowel begins as the duodenum connected to the stomach and ends as the ileum. The large bowel begins at the ileocecal junction (this is where the small bowel joins to the large bowel) and continues until the anus.
Bowel obstruction is a result of a mechanical obstruction to the flow of bowel content which can occur either in the small or large bowel, each of which has a different manner in manifesting itself. Bowel obstruction is an acute medical condition and patients will often experience symptoms dependent at which level of the bowel the obstruction has occurred.
Bowel obstruction due to adhesions is seen in patients with a history of abdominal surgery and can occur in both open and laparoscopic surgery. However they are more common after open abdominal surgery.
There are two classifications of bowel obstruction:
- Small Bowel Obstruction
Patients typically present with colicky central abdominal pain (intermittent cramping sensation) that can last a few minutes at a time, vomiting which is an early feature of small bowel obstruction, and abdominal distention may also be seen.
- Large Bowel Obstruction
Patients typically present with lower abdominal pain that can last several minutes and is higher in intensity compared to small bowel obstruction. Constipation is an early feature but vomiting is not a predominate symptom that patients experience.
Investigations carried out to diagnose bowel obstruction:
A set of routine blood tests are performed together with a venous blood gas test. The routine blood test will provide information in terms of infection, electrolyte status and renal function. Whereas the venous blood gas test allows for a quick snap shot of a patient’s condition to see how unwell they are based on lactate levels which will help in triaging the urgency of investigations performed.
As bowel obstruction can occur in both the small or large bowel, radiological imaging is performed to allow accurate diagnosis. The initial test is an abdominal x-ray which will highlight if this is a case of small or large bowel obstruction.
Following this a CT abdominal scan is performed which will allow better delineation of the obstruction, show any evidence of any abdominal masses, evidence of sepsis and perforation.
Management of bowel obstruction:
- Small Bowel:
This is commonly managed initially via a conservative approach. This will involve keeping the patient nil by mouth, provide intravenous fluid and insert a tube down the nose and into the stomach (nasogastric tube) to empty out its contents and allow decompression of the intestine. Blood tests are also carried out as bowel obstruction is associated with electrolyte imbalances which can be easily corrected. Analgesic (pain-relief) medication and antiemetics (which prevent vomiting) are given. However as there is a risk of sepsis and perforation, antibiotic cover is provided.
However if this fails to improve the obstruction then surgery may be used to relieve the obstruction. In an emergency setting where a patient is already septic or has evidence of bowel perforation surgery is carried out urgently in place of a conservative approach.
This is done either as a bowel resection via an open or laparoscopic approach and a temporary stoma (ileostomy) is created to allow healing of the inflamed bowel which will affect any attempt to directly connect the two ends.
- Large Bowel
Large bowel obstruction is more frequently a result of bowel masses and these may require an operation. However if the patient’s clinical status allows, investigations are performed to provide further details prior to proceeding with an operation.
However in some cases similar to small bowel obstruction patients can be septic or have evidence of perforation. Again in this setting a CT scan is performed which would provide an overview of the site of the obstruction and potential causes. Surgery is often performed via an open approach and the affected bowl is removed. If the cause is due to cancer then either a right or left hemicolectomy is performed. This involves the removal of either the right or left half of the bowel depending on where the cancer is located.