| Bowel obstruction | |
|---|---|
| Other names | Intestinal obstruction, intestinal occlusion |
 | |
| Uprightabdominal X-ray demonstrating a small bowel obstruction. Note multiple air fluid levels. | |
| Specialty | General surgery |
| Symptoms | Abdominal pain,vomiting,bloating, not passinggas[1] |
| Complications | Sepsis, bowelischemia,bowel perforation[1] |
| Causes | Adhesions,hernias,volvulus,endometriosis,inflammatory bowel disease,appendicitis,tumors,diverticulitis,ischemic bowel,tuberculosis,intussusception[2][1] |
| Diagnostic method | Medical imaging[1] |
| Treatment | Conservative care,surgery[2] |
| Frequency | 3.2 million (2015)<!— incidence —>[3] |
| Deaths | 238,733 (2019)[4] |
Bowel obstruction, also known asintestinal obstruction, is a mechanical orfunctional obstruction of theintestines that prevents the normal movement of the products ofdigestion.[2][5] Either thesmall bowel orlarge bowel may be affected.[1] Signs and symptoms includeabdominal pain,vomiting,bloating and not passinggas.[1] Mechanical obstruction is the cause of about 5 to 15% of cases ofsevere abdominal pain of sudden onset requiring admission to hospital.[1][2]
Causes of bowel obstruction includeadhesions,hernias,volvulus,endometriosis,inflammatory bowel disease,appendicitis,tumors,diverticulitis,ischemic bowel,tuberculosis andintussusception.[1][2] Small bowel obstructions are most often due to adhesions and hernias, while large bowel obstructions are most often due to tumors and volvulus.[1][2] The diagnosis may be made on plainX-rays; however,CT scan is more accurate.[1]Ultrasound orMRI may help in the diagnosis of children orpregnant women.[1]
The condition may be treated conservatively or withsurgery.[2] Typicallyintravenous fluids are given, anasogastric (NG) tube is placed through the nose into the stomach to decompress the intestines, andpain medications are given.[2]Antibiotics are often given.[2] In small bowel obstruction about 25% require surgery.[6] Complications may includesepsis, bowelischemia andbowel perforation.[1]
About 3.2 million cases of bowel obstruction occurred in 2015, which resulted in 264,000 deaths.[3][7] Both sexes are equally affected and the condition can occur at any age.[6] Bowel obstruction has been documented throughout history, with cases detailed in theEbers Papyrus of 1550 BC and byHippocrates.[8]
Depending on the level of obstruction, bowel obstruction can present withabdominal pain,abdominal distension, andconstipation. Bowel obstruction may be complicated bydehydration andelectrolyte abnormalities due to vomiting; respiratory compromise from pressure on thediaphragm by a distended abdomen, oraspiration of vomitus; bowelischemia orperforation from prolonged distension or pressure from a foreign body and subsequentlysepsis due tobowel flora.[9]
In small bowel obstruction, thepain tends to be colicky (cramping and intermittent) in nature, with spasms lasting a few minutes. The pain tends to be central and mid-abdominal. Vomiting may occur before constipation.[9] Common physical exam findings may include signs ofdehydration, abdominal distension with tympany, nonspecific abdominal tenderness, and high pitched tinkly bowel sounds.[10]
In large bowel obstruction, the pain is felt lower in the abdomen and the spasms last longer. Common symptoms include abdominal pain, distension, and severe constipation.[11] Constipation occurs earlier and vomiting may be less prominent. Proximal obstruction of the large bowel may present as small bowel obstruction.[9] Patients may notice a history of bloating and narrowing of stools before the onset of more severe symptoms. Symptoms can present quickly in the cases ofvolvulus and can present over a longer period of time in the setting of cancer. Common physical exam findings may include a palpablehernia, abdominal distension with tympany, nonspecific lower abdominal tenderness, and a rectal mass.[6]
Causes ofsmall bowel obstruction include:[2]
After abdominal surgery, the incidence of small bowel obstruction from any cause is 9%. In those where the cause of the obstruction was clear, adhesions are the single most common cause; in developed countries, about three-quarters of all small bowel obstructions are caused by postoperative adhesions.[12][14]
Causes of large bowel obstruction include:[15]
Outlet obstruction is a sub-type of large bowel obstruction and refers to conditions affecting the anorectal region that obstructdefecation, specifically conditions of the pelvic floor and anal sphincters. Outlet obstruction can be classified into four groups.[16]
| Diameter | Assessment |
|---|---|
| <2.5 cm | Non-dilated |
| 2.5-2.9 cm | Mildly dilated |
| 3–4 cm | Moderately dilated |
| >4 cm | Severely dilated |
The main diagnostic tools areblood tests,X-rays of the abdomen, CT scanning, andultrasound. If a mass is identified,biopsy may determine the nature of the mass.[citation needed]
Radiological signs of bowel obstruction include bowel distension (small bowel loops dilated >3 cm) and the presence of multiple (more than 2) air-fluid levels on supine and erect abdominalradiographs.[19] Ultrasounds may be as useful as CT scanning to make the diagnosis.[20]
Contrast enema or small bowel series or CT scan can be used to define the level of obstruction, whether the obstruction is partial or complete, and to help define the cause of the obstruction. The appearance of water-soluble contrast in the cecum on an abdominal radiograph within 24 hours of it being given by mouth predicts resolution of an adhesive small bowel obstruction withsensitivity of 97% andspecificity of 96%.[21]
Colonoscopy, small bowel investigation with ingested camera or pushendoscopy, andlaparoscopy are other diagnostic options.
![Small bowel obstruction on ultrasound[22]](/mt/?noimg=&dark=on&url=http%3a%2f%2fen.wikipedia.org%2fwiki%2fFile%3aUOTW_20_-_Ultrasound_of_the_Week_3.jpg)
Differential diagnoses of bowel obstruction include:
Treatment of small and large bowel obstructions are initially similar and non-operative management is usually the initial management strategy as the majority of small bowel obstruction resolve spontaneously with non-operative management.[10][24] Patients are monitored by the surgical team for signs of improvement and resolution of the obstruction on imaging; if the obstruction does not clear then surgical management for the treatment of the causative lesion is required.[25] In malignant large bowel obstruction, endoscopically placed self-expanding metalstents may be used to temporarily relieve the obstruction as a bridge to surgery,[26] or aspalliation.[27] Diagnosis of the type of bowel obstruction is normally conducted through initial plainradiograph of the abdomen, luminal contrast studies,computed tomography scan, orultrasonography prior to determining the best type of treatment.[28]
Further research is needed to find out if parenteral nutrition is of benefit to people with an inoperable blockage of the bowel caused by advanced cancer.[29]
In the management of small bowel obstructions, a commonly quoted surgical aphorism is: "never let the sun rise or set on small-bowel obstruction"[30] because about 5.5%[30] of small bowel obstructions are ultimately fatal if treatment is delayed. Improvements in radiological imaging of small bowel obstructions allow for confident distinction between simple obstructions, that can be treated conservatively, and obstructions that are surgical emergencies (volvulus, closed-loop obstructions,ischemic bowel, incarceratedhernias, etc.).[2] Exam findings of bowel compromise requiring immediate surgery include: severe abdominal pain, signs ofperitonitis such as rebound tenderness,elevated heart rate, fever, and elevated inflammatory markers on lab work, such aslactic acid.[10][24]
A small flexible tube (nasogastric tube) may be inserted through the nose into the stomach to help decompress the dilated bowel. This tube is uncomfortable but relieves the abdominal cramps, distention, and vomiting.Intravenous therapy is utilized and the urine output may be monitored with acatheter in thebladder.[31][10]
Most people with SBO are initially managed conservatively because in many cases, the bowel will open up. Some adhesions loosen up and the obstruction resolves. The patient is examined several times a day, andX-ray images are made to ensure he or she is not getting clinically worse.[32]
Conservative treatment involves insertion of anasogastric tube, correction of dehydration andelectrolyte abnormalities.Opioid pain relievers may be used for patients with severe pain but alternate pain relievers are preferred as opioids can decrease bowel motility.[10]Antiemetics may be administered if the patient is vomiting. Adhesive obstructions often settle without surgery. If the obstruction is complete surgery is usually required.
Most patients improve with conservative care in 2–5 days. When the obstruction is cancer, surgery is the only treatment. Those withbowel resection orlysis of adhesions usually stay in the hospital a few more days until they can eat and walk.[33]
Small bowel obstruction caused byCrohn's disease, peritonealcarcinomatosis, sclerosingperitonitis,radiation enteritis, and postpartum bowel obstruction are typically treated conservatively, i.e. without surgery.
The prognosis for non-ischemic cases of SBO is good with mortality rates of 3–5%, while prognosis for SBO with ischemia is fair with mortality rates as high as 30%.[34]
Cases of SBO related to cancer are more complicated and require additional intervention to address themalignancy, recurrence, andmetastasis, and thus are associated with a more poor prognosis.[23] Surgical options in patients with malignant bowel obstruction need to be considered carefully as while it may provide relief of symptoms in the short term, there is a high risk of mortality and re-obstruction.[35]
All cases of abdominal surgical intervention are associated with increased risk of future small-bowel obstructions. Statistics from U.S. healthcare report 18.1% re-admittance rate within 30 days for patients who undergo SBO surgery.[36] More than 90% of patients also form adhesions after major abdominal surgery.[37] Common consequences of these adhesions include small-bowel obstruction, chronic abdominal pain, pelvic pain, and infertility.[37]
Surgical treatment of large bowel obstruction, typically due to large tumors, was attempted as early as 1776, though long-term survival and wider use waited for the development ofsterile technique andanesthesia in the 19th century.[12] The first known case of small bowel obstruction due to post-surgical adhesions was reported in 1872.[12] The first child to survive surgery forintussusception was a two-year-old girl in 1871.[12]
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