Q: I have had surgery for appendicitis and a hernia. Last week out of nowhere I developed abdominal pain and vomiting, and although the doctors told me my small bowel was blocked and I had to be hospitalized, it resolved after a couple of days. What is this, and will I get it again?

A: During transit through the long tubular structure of the intestines (20+ feet of small and 5+ feet of large intestines), fluid and nutrients are absorbed and waste is eliminated. A bowel obstruction occurs when there is a blockage of the intestines; about 80% occur in the small intestines and the rest in the large intestines. Bowel obstructions can be partial (some fluid can pass through) or complete.

During a bowel obstruction the part of the intestines proximal to the blockage expands as it fills up. Pressure from this expansion causes swelling and edema of the bowel wall. Fluid loss (from vomiting and edema) can cause dehydration and electrolyte imbalances, which can be severe and even life threatening. The blood supply to the intestines can be compromised either directly from the bowel twisting/being squeezed or from the swelling/edema, and if this occurs part of the bowel tissue can necrose (die) and then perforate. Spillage of bowel contents into the abdominal cavity can cause an infection (peritonitis) which can be life threatening.

Small bowel obstructions (SBOs) are common, accounting for one of every 25 to 50 emergency department visits and over 300,000 hospitalizations (20% of surgical all admissions) every year. The average age of patients with an SBO is 64 years old.

The most common cause of SBO, responsible for 60% of cases, is adhesions from previous surgeries (basically scar tissue “grabbing” the bowel). The lifetime risk for an SBO after having an open appendectomy is about 10%, with the risk after open gallbladder surgery around half that. Other causes include cancer (responsible for 20% of SBOs), hernias (10%), inflammatory bowel disease such as Crohn’s disease (5%) and other causes (including volvulus, intussusception, gallstone ileus and others).

The symptoms of SBO typically include colicky abdominal pain that waxes and wanes, bloating, and (especially if the blockage is close to the stomach) nausea and vomiting. Very early in the course of an SBO many patients have episodes of diarrhea (only fluid passes through), and later constipation and the inability to pass gas.

The severity of SBOs is graded on the American Association for the Surgery of Trauma scale, with Grade I having only a partial obstruction and minimal intestinal distention, Grade II having a complete obstruction but without any compromise of the bowel tissue, Grade III having complete obstruction but with compromised bowel, Grade IV having complete obstruction and perforation of the bowel wall and Grade V having complete obstruction, perforation and contamination/infection in the abdominal cavity.

The diagnosis of an SBO is suspected based on the history/physical exam and is confirmed with abdominal x-rays (flat and upright) which show air/fluid levels. Since regular x-rays can miss some SBOs, a CAT scan or other tests are usually indicated.

The initial treatment of an SBO is to correct any fluid deficit and electrolyte imbalance; then a tube may be placed through the nose into the stomach to decompress the over-expanded bowel (for a proximal SBO). If compromise of blood flow to the bowel or perforation is suspected, the patient will be taken for an early operation to address the cause of the SBO and to remove any dead bowel. Many general surgeons consider that “the sun should not rise or set on an SBO”, meaning that if a patient does not show some improvement with non-surgical therapy within the first 12 to 24 hours then they should be considered for surgical exploration. Although up to 85% of SBOs resolve with non-surgical treatment, surgical “lysis” of adhesions (cutting away scar tissue) to prevent recurrences may be indicated.

About 40% of surgeries for SBO are to lyse adhesions, 20% are for lysis and bowel resection, and the rest are for bowel resection and/or hernia repair, or for treatment of intra-abdominal cancer. Laparoscopic (minimally invasive surgery) lysis of adhesions may be considered in some patients; the best candidates for this are those with mild and proximal adhesions, no cancer, no inflammatory bowel disease and not more than one previous surgery for SBO.

Within 10 years of an episode of SBO recurrence is unfortunately common, occurring in over 20% of patients having had one episode of an SBO and up to 50% or higher (depending on the cause) for patients having had multiple episodes. Surgery to lyse adhesions may decrease the likelihood of recurrence, but even after this surgery about 15% of patients will still have a recurrence within 10 years.

Jeff Hersh, Ph.D., M.D., can be reached at DrHersh@juno.com