Intestinal obstruction is an important gastrointestinal emergency and a common cause of hospitalization. Most of the patients with intestinal obstruction report to surgeons or surgical care units. Some of them however report to physicians or medical emergency units. Intestinal obstruction carries a high risk of mortality and morbidity if surgical therapy is inappropriately delayed because of misdiagnosis.
The Ministry of Health and Family Welfare has issued the Standard Treatment Guidelines for Intestinal Obstruction. Following are the major recommendations :
Acute intestinal obstruction occurs when there is an interruption in the forward flow of intestinal contents. This interruption can occur at any point along the length of the gastrointestinal tract. The clinical presentation varies depending on the severity, duration, site and type of intestinal obstruction. The classical clinical tetrad of presentation is colicky abdominal pain, nausea and vomiting, abdominal distention, and progressive constipation. There are two types of intestinal obstruction-mechanical and adynamic.
Mechanical intestinal obstruction
Site of obstruction: The obstructive pathology may lie in the proximal small intestinal or distal intestine including the colon.
Grade and severity of the obstructing lesion: The intestinal obstruction could be either complete or incomplete (partial). While in the partial intestinal obstruction, the gas or liquid stool can pass through the point of narrowing, in complete intestinal obstruction, the obstruction is complete and there is no passage of gas or the liquid stool beyond the point of the obstruction. Partial obstruction is further classified as high grade or low grade according to the severity of the narrowing. In general, surgical intervention is often required for complete intestinal obstruction; partial intestinal obstruction can be treated using conservative measures.The mechanical intestinal obstruction could remain uncomplicated or may get complicated by vascular compromise, intestinal perforation and septicemia.
Adynamic intestinal obstruction
There are two types of a dynamic intestinal obstruction – paralytic ileus and acute intestinal pseudo obstruction.
It is important to classify intestinal obstruction into above mentioned categories as the treatment of intestinal obstruction will vary according to the site, severity and cause of the intestinal obstruction. Therefore, following questions should be addressed while dealing with a patient with intestinal obstruction:
1. Differentiation between complete mechanical obstruction, partial mechanical obstruction or a dynamic obstruction
2. The site of obstruction: Small bowel obstruction (proximal or distal) vs. large bowel obstruction (colon/rectal)
In simple intestinal obstruction, the intestine is occluded at one point. Fluid and chyme accumulate proximal to the site of intestinal obstruction. This leads to impairment in intestinal water and electrolyte absorption and enhanced intestinal secretion resulting in volume depletion. Stasis of intestinal contents predisposes to bacterial overgrowth (predominantly anaerobes) in the segment proximal to obstruction. The bacterial overgrowth leads to bacterial fermentation and increased production of gas. Accumulation of liquid and gas in the intestine leads to intestinal dilatation which induces local inflammation and neuro-endocrine reflexes that initially increase enteric propulsive activity to attempt to overcome the obstruction. Intestinal motility gradually decreases as intestinal muscle becomes fatigued.Intestinal dilatation gradually compromises vascular perfusion because of increasing intraluminal pressure and intramural tension. Forward arterial flow is severely compromised when the intraluminal pressure reaches the diastolic pressure,and ceases when the intraluminal pressure reaches the systolic pressure. Venousobstruction causes increased intraluminal fluid transudation and intramuraledema. Almost 80% of blood flow to the intestine goes to the mucosa, therefore intestinal mucosa is highly sensitive to ischemia as it is perfused by end arteries and has a high rate of metabolic activity.
In closed-loop obstruction, an intestinal segment is occluded at two points.Common forms of closed loops include an incarcerated hernia, in which a loop of the intestine is compressed at both ends within a hernial sac, and volvulus, in which a loop of intestine is mechanically compressed at both ends because of a twist in the supporting mesentery. If the ileocecal valve is competent, an obstructive lesion in the colon causes a closed loop due to a pathologic mechanical obstruction at the distal end and a physiologic occlusion at the ileocecal valve proximally. If the ileocecal valve is incompetent, the obstructive lesion in the colon produces a simple obstruction as the colon is decompressed by way of the small intestine. A closed loop of intestine rapidly dilates because of the lack of a proximal and a distal outlet for the accumulated gas and liquid. The mucosa consequently develops ischemia rapidly. Extrinsic compression that strangulates mes enteric vessels (e.g. at a point of volvulus or at the neck of a hernial sack) exacerbates the ischemia and rapidly produces intestinal gangrene or necrosis and perforation.
Incidence of The Condition In Our Country
The most common (75%) cause of small intestinal obstruction is post-operative adhesion’s. The rate of adhesive small intestinal obstruction development is highest in the first few postoperative years following the index surgery, particularly after colorectal surgery, but the risk remains life-long. The risk of recurrent intestinal obstruction from adhesion’s after 10 years of the index surgery varies widely from 15 to 50%. Although, post-operative intestinal obstruction recovers mostly with conservative management, 25 to 66% of them may require exploratory laparotomy and adhesinolysis. Although hernia was the second most important cause of intestinal obstruction, there has been a marked decline of intestinal obstruction due to hernia from 40% in the 1960s to 15%, presumably due to an increased rate of elective hernia repair. Other causes of intestinal obstruction include intestinal tuberculosis, bands, and volvulus.
Optimal Diagnostic Criteria, Investigations
Clinical features of intestinal obstruction :
The clinical presentation varies depending on the severity, duration, and type of intestinal obstruction. The classical clinical tetrad is colicky abdominal pain, nausea and vomiting, abdominal distension and progressive constipation.
Differentiation between proximal vs distal intestinal obstruction
Proximal intestinal obstruction typically produces epigastric pain that occurs every 3 to 4 minutes, with frequent bilious vomiting. Distal intestinal obstruction typically produces peri-umbilical pain that occurs every 15 to 20 minutes, with infrequent feculent emesis. Abdominal distension is more marked in the distal obstruction as there is a large length of the intestine proximal to the obstructive lesion, which can accumulate volumes of fluid and gas. Closed-loop obstruction often presents with pain out of proportion to the abdominal signs because of concurrent mesenteric ischemia. Inspection occasionally reveals visible peristalsis. Air-filled intestinal loops produce abdominal tympany. Palpation reveals mild generalized abdominal tenderness. Peritoneal signs, such as rebound tenderness and guarding, are typically absent, unless intestinal necrosis or perforation supervenes. Intestinal sounds are initially high-pitched (tinkling) and hyperactive, with audible rushes or borborygmi corresponding to paroxysms of abdominal pain, but become progressively hypo active and softer, and then disappear because of intestinal fatigue. Patients with obstructive lesion in the rectum may give a history of spurious diarrhoea, altered bowel habit and progressive constipation before presenting with large bowel obstruction.
Features that suggest complications
The development of rigors, high fever, or systemic toxicity suggests that the obstruction may be complicated by intestinal necrosis or perforation. In tussuception typically presents in infants with episodic abdominal pain,currant jelly stools, and bilious vomiting.Physical examination reveals an acutely ill, restless, and febrile patient. Signs of intravascular volume depletion include tachycardia, orthostatichypotension, dry mucous membranes, and poor skin turgor. Jaundice suggests possible gallstone ileus or malignant obstruction.
Features that suggest aetiology of intestinal obstruction
A good systemic and abdominal examination can provide important clues to the a etiology of the intestinal obstruction. A history of previous abdominal surgery especially intestinal surgery can point towards the most common cause of intestinal obstruction i.e. postoperative adhesive intestinal obstruction. Other causes of intestinal obstruction such as abdominal scars, clinically obvious external incarcerated hernia (femoral, inguinal, umbilical, or incisional), per-rectal examination (fecal impaction, or a rectal mass), and digital examination of the stoma to rule out stomal obstruction in patients with colostomy or ileostomy. Presence of hepatomegaly, splenomegaly, a palpableabdominal mass, or periumbilical (Sister Mary Joseph nodule), inguinal, and right supraclavicular (Virchow node) lymphadenopathy may suggest presence of a malignant obstructive lesion in the intestine with systemic dissemination.
Evaluation at the time of acute obstruction
Plain upright abdominal radiograph
Plain upright abdominal X-ray film should be done for initial confirmation of intestinal obstruction in patients presenting with clinical signs and symptoms of intestinal obstruction. It can confirm intestinal obstruction in approximately 60%and its positive predictive value approaches 80% in patients with high-grade intestinal obstruction.Presence of multiple air fluid levels (> 3) in the erect film is an important sign pointing towards the diagnosis of intestinal obstruction. At times when the patient is too sick a decubitus film also may help in detecting the presence of air fluid levels. Large air fluid levels occurring more or less at the same level on the radiograph are suggestive of paralytic ileus whereas air fluid levels at different levels are more likely in a dynamic obstruction. Additionally, the abdominal film can show dilation of intestinal loops (dilation >3 cm), and a transition zone between dilated and non dilated intestinal segment. The pattern of dilation can suggest the site of intestinal obstruction. While the supine abdominal film in patients with small intestinal obstruction shows dilatation of multiple loops of small intestine, with a paucity of air in the large intestine, the large intestinal obstruction shows dilatation of the colon, with decompressed small intestine in the setting of a competent ileocecal valve. It is important to assess the diameter of the distended caecum in such cases as dilatation beyond 10 cm indicates impending caecal rupture. Air-filled loops of small intestine are distinguished from those of large intestine by their more central abdominal location, by their narrower calibre even when dilated, and by the presence of valvulaeconniventes that extend across the entire luminal diameter as opposed to the colonic haustral folds that extend only partially across the luminal diameter. Presence of free air under the diaphragms immediately confirms intestinal perforation.Although this finding diminishes in significance if it is found on an Xray done in the early postoperative period following an abdominal surgery.
Limitation of abdominal radiograph: Plain abdominal film can appear normal in early obstruction and in high gut obstruction (jejunal or duodenal obstruction) and thus may be misleading.
An abdominal CT scan,non contrast and contrast enhanced (both oral and intravenous contrast; water-soluble contrast preferred) is appropriate for further evaluation of patients with suspected intestinal obstruction in whom clinical examination and radiography do not yield a definitive diagnosis. CT is very useful in a patient suspected to have intestinal obstruction and it can show all that necessary information about the intestinal obstruction. The presence of a discrete transition point helps guide operative planning.
CT findings in patients with intestinal obstruction include dilated loops of intestine proximal to the site of obstruction, with distally decompressed intestine. In addition, CT can identify emergent causes of intestinal obstruction, such as volvulus or intestinal strangulation.Although CT is highly sensitive and specific for high-grade obstruction, its value diminishes in patients with partial obstruction. In these patients, oral contrast material may be seen traversing the length of the intestine to the rectum, with no discrete area of transition.
A C-loop of distended intestinal with radial mesenteric vessels with medial conversion is highly suspicious for intestinal volvulus. Thickened intestinal walls and poor flow of contrast material into a section of intestinal suggests ischemia, whereas pneumatosisintestinalis, free intra-peritoneal air, and mesenteric fat stranding suggest necrosis and perforation. The CT can also identify intussusceptions easily by picking up the intussusceptum in the intussuscepiens, as the mesenteric fat and vasculature can be identified within the lumen of the intestine or a ‘double target sign’ can be seen on cross-sectional imaging.
The American College of Radiology recommends non-contrast CT as the initial imaging modality of choice.However, because most causes of small intestinal obstruction will have systemic manifestations or fail to resolve necessitating operative intervention the additional diagnostic value of CT compared with radiography is limited. Radiation exposure is also significant. Therefore, in most patients, CT should be ordered when the diagnosis is in doubt, when there is no surgical history or hernias to explain the etiology, or when there is a high index of suspicion for complete or high-grade obstruction.The CT signs of strangulation include:a thickened intestinal wall because of intestinal wall edema, inflammation, or intramural hemorrhage; mural thumb-printing from intramural hemorrhage or edema; pneumatosisintestinalis from intramural gas produced by bacteria; absence of enhancement with intravenous contrast because of vascular hypoperfusion;hazy or streaky mesentery or ‘‘dirty’’ fat from inflammatory infiltration, portal venous gas, target sign, and ascites.
Evaluation after resolution of an episode of intestinal obstruction with conservative management
After the acute intestinal obstruction has resolved, the cause of intestinal obstruction should be investigated and treated appropriately (medical or surgical) depending upon the diagnosis. The basic principal of investigation is to find out site, cause, extent and etiology of the intestinal obstructive disease.
- Small intestinalevaluation: Barium meal follow through (BMFT), Enteroclysis or CT enteroclysis
- Large intestinal evaluation: Preferably colonoscopy and if not available barium enema
- Histological examination of the biopsies for pathological diagnosis
- Microbiological tests such as PCR and culture for tuberculosis in appropriate clinical setting
Evaluation after control of an episode of intestinal obstruction with surgery
Often, in patients with refractory adhesive intestinal obstruction, all that is required at laparotomy is adhesiolysis to separate the adhesions and relieve the obstruction. In such cases there is no need for any excision of intestine unless there is a strangulated gangrenous segment of intestine. Whenever resection is warranted, the resected specimen should be evaluated both histologically and microbiologically to determine the etiology. In some patients, inflammatory lesions such as tuberculosis or Crohn’s disease, malignant lesions such as adenocarcinomas/gastrointestinal stromal tumors or lymphomas, a specific treatment will be required for the management of the disease post resection.
Treatment & Referral Criteria
The principles in management of acute intestinal obstruction include correction of abnormalities in the fluid and electrolyte imbalances, gastric decompression, and bowel rest, prevention of infection, analgesics, and specific treatment for cause of obstruction.
- Monitoring of clinical and hemodynamic status
Pulse, Blood pressure
- Fluid and electrolyte balance
Intravenous fluid: Isotonic crystalloids
Arterial blood gas: Correction of acid base abnormalities
Correction of electrolyte imbalance, especially hypokalemia
Measurement of urine output
- Symptomatic treatment
- Oral administration of water-soluble contrast agent (Urograffin)(see below)*
Analgesics such as intravenous anti-cholinergics or NSAIDS
- Anti-emetics: Metoclopromide, ondansetron
Antibiotics are used to treat intestinal overgrowth of bacteria and translocation across the intestinal wall. The presence of fever and leukocytosis should prompt inclusion of antibiotics in the initial treatment regimen. Antibiotics should have coverage against gram-negative organisms and anaerobes, and the choice of a specific agent should be determined by local susceptibility and availability.
- Nutritional support:
If intestinal obstruction is prolonged (for example ,in patients with post operative state)and the patients cannot be fed enterally, they should be given total parenteral nutrition. Generally speaking, a previously healthy adult can tolerate 5-7 days of fasting or bowel rest without any significant clinical debility. Beyond this period appropriate parenteral nutritional support is advisable.
Outcome following conservative management
Conservative management is successful in 40 to 70 percent of clinically stable patients, with a higher success rate in those with partial intestinal obstruction.Although conservative management is associated with shorter initial hospitalization, there is also a higher rate of eventual recurrence. With conservative management, resolution generally occurs within 24 to 48 hours. Beyond this time frame, the risk of complications, including vascular compromise, increases. If intestinal obstruction is not resolved with conservative management, surgical evaluation is required.
Patients who develop adhesive intestinal obstructionof the small intestinein the postoperative period(both early and late)constitute a special group of patients in whom a new form of conservative intervention is indicated as outlined below.After the baseline abdominal radiographs have documented intestinal obstruction, the next step is to administer 100 ml of urograffin(watersoluble contrast agent) diluted in 400 ml of saline or drinking water orally or through the nasogastric tubewhich has already been inserted as part of the conservative management of intestinal obstruction. Thereafter, abdominal radiographs are obtained at 8-12 h intervals till 24 hours of ingestion of urograffin.The appearance of contrast in the colon within 8-24 h after its administration predicts resolution of small intestinal obstruction with a sensitivity of 96% and specificity of 98%. Water soluble contrast agent administration is effective in reducing the need for re-operation and shortening the hospital stay compared with conventional ‘drip-and-suck’ regimen. This simple therapeutic maneuver also has a diagnostic valueand can delineate the level of obstruction in those patients in whom the contrast fails to reach the large intestine in the stipulated time frame. In those patients in whom water soluble contrast agent does not reach colon, the probability of need for surgery is higher. While administration of water soluble contrast agent can occasionally be repeated, one should keep a close vigil on abdominal signs and clinical status of the patient. This modality can also be used in other patients with intestinal tuberculosis or Crohn’s disease who are likely to have a partialsmall intestinal obstruction.
Indications for surgery
Although there are clinical features which allow a clinician to decide about the time of surgery and also predict or suggest resolution of intestinal obstruction with conservative management in the index patient, such a prediction is challenging at occasions. As such, presence of fever, tachycardia, leukocytosis, or anion-gap acidosis, in the setting of abdominal imaging consistent with obstruction constitutes a low threshold for laparotomy. Peritonitis remains an absolute indication for exploration today as it did decades ago.There are clinical scenarios that are considered somewhat exempt from an “early” operative approach in the absence of peritonitis. These include small bowel obstruction in the early postoperative period (unless following laparoscopic surgery), tuberculosis, Crohn’s disease, or carcinomatosis. Postoperative small bowel obstruction occurs within 4–6 weeks of abdominal surgery with an estimated incidence of 1–4%. Caused by filmy adhesions in most open cases, up to 90% of these obstructions resolve (dissolve or reform) with non-operative management within 7–14 days of the index operation. The exception to this watchful waiting approach is postoperative obstruction following laparoscopic surgery which warrants an early surgical approach more often than not. The cause of obstruction will depend on the underlying operation, but it is likely that (amongst other causes) intestine is incarcerated within a peritoneal defect caused by trocar placement. Clinical situations such as, volvulus, obstructed hernia, large bowel obstruction with gross cecal dilatation and instances where a closed loop obstruction is suspected should have a low threshold for surgical intervention.
Patients with an intestinal obstruction that resolves after reduction of a hernia should be scheduled for elective hernia repair, whereas immediate surgery is required in patients with an irreducible or strangulated hernia. Stable patients with a history of abdominal malignancy or high suspicion for malignancy should be thoroughly evaluated for optimal surgical planning. Abdominal malignancy can be treated with primary resection and reconstruction or palliative diversion, or placement of venting and feeding tubes. There is emerging evidence to suggest that patients with colonic/rectal obstruction due to malignancies are best treated by emergency surgical diversion/or resection (wherever feasible) rather than colonoscopic stenting.
Patients with post operative adhesive obstruction
Treatment of stable patients with intestinal obstruction and a history of abdominal surgery present a challenge. Conservative management of a high-grade obstruction should be attempted initially, using nasogastric suction and decompression, aggressive intravenous rehydration, and antibiotics. Most show improvement in 48 hours. If not, then a therapeutic trial with water soluble contrast agent (as described above) is warranted in the absence of peritoneal signs.
The cause of the intestinal obstruction should be treated appropriately.
*Situation 1: At Secondary Hospital/ Non-Metro situation: Optimal Standards of Treatment in Situations where technology and resources are limited
a) Clinical Diagnosis:
b) Investigations: Haemogram, electrolytes, sugar, urea levels, chest and abdominal X rays
Standard Operating procedure
a. Inpatient: All patients suspected or confirmed to have intestinal obstruction should be admitted and treated appropriately as described above.
b. Outpatient: Not applicable
c. Day Care: not applicable
Non availability of a surgeon,basic facilities as outlined above
A sick patient
Failed conservative management
Obstruction secondary to suspected malignancy
Obstruction in the setting of IBD
*Situation 2: At Super Specialty Facility in Metro location where higher-end technology is available
a) Clinical Diagnosis : As above
b) Investigations :
Hemogram, electrolytes, RFT, LFT, Blood gases, Serum lactate levels, X-ray: chest/abdomen, CT scan, endoscopic facilities
Standard Operating procedure
a. Inpatient : as outlined above
b. Outpatient Not recommended; provide follow up and counseling after discharge
c. Day Care : Not recommended in the acute setting;
Guidelines by The Ministry of Health and Family Welfare :
Govind K Makharia Additional Professor, Department of Gastroenterology and Human Nutrition, AIIMS, New Delhi
DrSujoy Pal Associate Professor, Department of Gastrointestinal Surgery, AIIMS, New Delhi