Symptoms of bowel obstruction depend on underlying pathophysiology. Abdominal discomfort and distention are some of the first indications of this condition. In most of the cases, stool discharge may be affected. Vomiting, malnutrition, fever and hypotension are some other common symptoms.
In many cases, symptoms indicate the location and nature of blockage. Vomiting along with colicky pain is seen if the obstruction is in the proximal region of the small intestine. When the obstruction is in the distal part of the small intestine, pain may remain for main days. They may also present with abdominal distension. An increasing pain may indicate more serious conditions like ischemic bowel obstruction or a strangulated SBO.
Onset of symptoms in LBO is slower. Acute form of bowel obstruction often have abrupt onset of manifestations. Those with colon carcinoma or diverticulitis  may present with chronic constipation or a strain to pass stools. Strictures and diverticulitis may cause a chronic pain in the lower quadrant of the abdomen. Obstruction caused by neoplasms often have sudden weight loss as one of the symptoms. Inability to pass stools may be associated with complete blockage of the large intestine. It may also lead to anorexia and, at a later stage, feculent vomiting.

Differentiating the different types of obstruction is important in deciding the treatment. Some of the essential laboratory tests that is helpful in diagnosis include serum levels of blood urea nitrogen and creatinine, complete blood count, lactate dehydrogenase tests and urinalysis. Measuring levels of phosphate, creatinine kinase and liver panels help in differentiating bowel obstruction from biliary or hepatic disease.

Plain radiographs in two position, supine and upright, are useful in identifying simple obstructions in small intestine [5]. The sensitivity of plain radiograph is around 75% and specificity 53%. Mean level width above 25 mm is considered as a diagnostic indicator of complete obstruction [6]. Partial blockages can be differentiated from complete blockages using enteroclysis. It can be used to distinguish neoplasms from adhesions. The method uses two contrasts for better differentiation. Barium is avoided as a contrast if perforations are suspected. Patients presenting with fever, tachycardia and abdominal pain are recommended to undergo a CT scan. This imaging technique is useful in differentiating strangulated obstruction from other types of blockages, particularly when radiography records are not confirmatory. It also helps in distinguishing the extrinsic cause of blockages from intrinsic lesions. Magnetic resonance imaging is also helpful in differentiating the different types of obstructions [7]. The site of obstruction and the actual cause also can be defined using MRI. To opt for a less invasive procedure, ultrasonography may be a good option and has very good specificity.

Treatment of the condition depends on the type and the potential risk factors. Intestinal tube is a conservative method of treatment which keeps the lumen open for the movement of bowel contents. Nasogastric tube is used to suction out the contents of the lumen and to prevent aspiration. This method helps in improving the usual symptoms of the condition. Surgical resection is the suggested method in the treatment of obstruction caused by tumor. Drainage will help to remove obstruction in case of intra-abdominal abscess. Obstruction that occurs after a radiation therapy may be treated with steroids. Under emergency, bowel decompression, fluid resuscitation followed by analgesic and antiemetic are recommended. Surgical intervention is recommended for strangulated form of SBO. Patients with complete obstruction may have to undergo surgery if other non-surgical methods do not show improvement. One of the safe methods for SBO is laparoscopy [8].

In LBO, fluid resuscitation and antibiotics are the initial treatment modalities. Patients are suggested surgical consultation, when needed. Nasogastric tubes are used in case of colonic distension. Patients with volvulus, bowel ischemia or loop obstructions need surgery. Patients with pseudo-obstruction are recommended bowel rest, hydration and treatment of the underlying disease. Pseudo-obstruction that do not show improvement with conservative treatment need pharmacologic management [9]. Surgical resection is recommended for colonic pseudo-obstruction with perforation [10].

Outcome of intestinal obstruction, both large and small bowel obstruction, is good if treated early. Strangulated obstructions in the small intestine, if left untreated, lead to death in all patients. Surgery reduce the mortality rate considerably in the case of strangulated SBO, particularly if it is performed within two days. Delayed surgery reduces the chances of survival. Some of the factors that affect prognosis in SBO include age, comorbidity, and treatment time. SBO is associated with complications like wound dehiscence, aspiration, sepsis and intra-abdominal abscesses.
In LBO, bowel ischemia and perforation have poor prognosis. Mortality rate for LBO ranges from 20% to 40%, with the highest for colonic obstruction with perforation. When treatment is provided early enough, pseudo-obstruction also has a good prognosis. Some of the common complications associated with LBO include peritonitis, sepsis, dehydration, perforation and intra-abdominal abscesses.

Based on the site of obstruction, intestinal obstruction is classified into small bowel obstruction (SBO) and large bowel obstruction (LBO).

Small bowel obstruction – post-surgical adhesions are the most common cause of this condition. In acute cases, the adhesions develop within three to four weeks of surgery. In chronic SBO, adhesions develop several years after the surgery. Groin hernia, tumor, inflammatory bowel disease and volvulus also lead to obstruction in small intestine. In patients who have had abdominal surgery earlier, Crohn’s disease may lead to chronic form of SBO by progressive fibrosis. In children, SBO may be caused by congenital atresia, pyloric stenosis and intussusception.

Large bowel obstruction – the most prominent etiologic factor for LBO is neoplasms, accounting to 60% of obstructions in the large intestine. Some other common causes of this intestinal obstruction include strictures, volvulus, intussusception and impaction. Colonic wall diverticulitis results in fibrosis and thickening of the wall which reduces the lumen of large intestine.

Causes of bowel obstruction may be divided into three types – extraluminal, intrinsic, and intraluminal. Extrinsic lesions that lead to bowel obstructions include adhesions, hernia, volvulus, extrinsic neoplasms, intra-abdominal abscesses, aneurism, hematomas, and endometriosis. Intussusception, congenital malformation, neoplasms, and inflammatory strictures belonging to internal lesions that cause bowel obstruction.

About 20% of emergency admissions for surgery is due to bowel obstruction. In elderly patients, mortality rate for the different types of obstruction ranges from 7% to 14% [2]. SBO accounts for about 80% of surgical admissions due to intestinal obstruction. Colonic obstruction is more common among elderly patients as neoplasms and other etiologic factors are prevalent in this age group [3]. Intussusceptions account for 80%-90% of bowel obstructions in children. This condition forms one of the most common causes of abdominal emergency in infants and children. In neonates, anatomic defects like imperforate anus may cause bowel obstruction. Around 3.2% of the patients who have undergone bariatric surgery develops SBO. More than half the cases of LBO is caused by colon carcinoma, out of which 5%-10% are complete obstructions that require surgery.

Nervous and vascular defects of the intestine and structural changes in the intestinal wall leads to the pathophysiology of intestinal obstruction. Nervous and vascular incompetence may reduce peristalsis while alterations in the intestinal wall reduces the size of the lumen affecting the passage of content in the tract. Damage caused by bowel obstruction depend on factors like degree of blockage, loss of functionality, and the pressure inside the lumen of the intestine. As the lumen size decreases, malabsorption syndrome results. Complete obstruction of the lumen is a potentially life-threatening condition. It leads to changes in the fluid and electrolyte balance resulting in their leakage to surrounding peritoneum.

In SBO, air and secretions may collect in the intestine favoring further accumulation of fluid. Thus, peristalsis increases in the regions above and below the site of obstruction. If obstruction is in the proximal region of the intestine, it may lead to vomiting. With the progress of the disease, intraluminal pressure may increase considerably, leading to spacing of the electrolytes and proteins into the intestinal lumen. Loss of fluid along with fluid and electrolytes result in dehydration which may be severe. Necrosis and ischemia results from strangulation of the small intestine. This can lead to peritonitis and perforation in the intestine.

When blockage is caused by mechanical obstruction factors, it results in dilatation of large bowel above the site of obstruction. This impairs vascular and nervous supplies to the bowel. Mucosal edema in the intestine along with ischemia lead to systemic toxicity and dehydration. Perforation may also follow, and the process may be expedited in the presence of hernia or a closed ileocecal valve. Pseudo-obstruction of the colon may reduce peristalsis and allow fluid and gas to accumulate. The right colon and cecum are the two regions that are most commonly affected by pseudo-obstruction. Obstruction leads to perforation in about 15% of the cases [4].

Prevention of intestinal blockage depends on the etiology of the condition. Treating the causative factors like hernias and tumors help in preventing the development of blockage in the intestine.

Intestinal obstruction, or bowel obstruction, refers to the partial or complete blockage to the transit of contents in the small or large intestine. Intestinal obstruction is a serious condition requiring early diagnosis and treatment. It can be categorized on the basis of different factors like site of obstruction, severity of blockage, and absence or presence of ischemia. Blockage can be due to mechanical interruption of movement or a pseudo-obstruction. The treatment modalities differ for mechanical and pseudo-obstruction and hence it is important to differentiate the cause of blockage in intestine [1]. Symptoms of the condition depend on severity of obstruction. A number of factors lead to bowel obstruction including neoplasms, diseases, strictures and postoperative adhesions. Obstructions are one of the most common causes of acute abdominal pain and account for one fifth of the admissions in emergency.

Intestinal obstruction refers to blockage of the intestine that affects the passage of contents in the tract. The blockage may be seen in the small or large intestine and may be partial or complete. When blockage develops, contents accumulate above the site of obstruction resulting in distention of bowel. If the lumen of the bowel is completely blocked it is considered as an emergency. Intestinal obstruction is one of the most common causes of acute abdominal pain and admission to emergency.

Both mechanical and non-mechanical factors lead to blockage. Stoppage of peristalsis causes distention of the bowel as the contents of the gut stop moving. Formation of scar tissue after a surgery of the abdomen, hernia, and volvulus are some other common causes of blockages in the small intestine. Severe constipation, Crohn’s disease, gallstones, congenital abnormalities of the bowel, tumors, infections inside the abdomen, and some foreign bodies may also cause bowel obstruction.

Symptoms of bowel obstruction depend on the site and degree of blockage. Abdominal pain is one of the earliest and most common symptoms of obstruction. Distension, constipation or diarrhea, vomiting, inability to pass gas, failure to pass stool, decreased appetite and bloating are other common symptoms. It is important to call the doctor if the pain is severe and constant. This may indicate perforations in the intestine and that blood supply to the gut is cut off. Medical history helps the doctor to assess the cause of the disease. Thorough physical examination followed by CT scan or an X-ray helps in locating the obstruction and identifying the cause of the condition.

Treatment of intestinal obstruction is based on the actual cause. Nasogastric tube inserted into the throat helps remove the contents from the gut. Fluid and electrolyte balance has to be maintained for improving the symptoms. If the blockage is partial, surgery may not be needed. Less invasive laparoscopy may be suggested to locate and remove the obstruction. To keep the lumen of the gut open, stents may be used, particularly in elderly patients. Surgery is used to remove the cause of blockage or to remove a part of the bowel which is completely blocked. Steroids, painkillers, antiemetics and antibiotics are often suggested to control symptoms of blockage. Outcome of the condition often depends on the cause. When treated early and appropriately, blockage can be easily treated.

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