The elderly comprise the fastest-growing segment of the United States’ population; thus, surgeons will be faced with increasing numbers of older patients particularly those with intestinal obstruction. These patients will be more challenging to care for since they will have more complex medical comorbidities than younger patients. This challenge will be compounded by the fact that many of these patients will have undergone previous abdominal surgery and a small but growing minority might have undergone multiple abdominal procedures. Since intestinal obstruction is one of the more common surgical diseases in the elderly, it is imperative that surgeons sharpen their understanding of the evaluation and treatment of patients with bowel obstruction.

Intestinal obstruction is a common cause of pain and disability in the elderly, and this disease places a large economic and resource burden on the healthcare system. A review of US healthcare data revealed an annual estimated cost of well over one billion dollars to treat adhesion-related bowel obstruction, and many of these patients were noted to be of advanced age [1]. Unlike younger patients, where a vast array of nonobstructive surgical disease states cause the patient to seek medical care, intestinal obstruction is a far more frequent cause of abdominal pain in the elderly. The obstruction is due to a much broader range of etiologies. Although adhesive bowel obstruction is common in the elderly, additional etiologies include gallstone ileus, obturator or rare hernias, bezoars, cecal and sigmoid volvulus, as well as more common problems such as inguinal or incisional hernias, inflammatory bowel disease, and neoplasms.

Intestinal obstruction is truly a “surgical disease” which has been affirmed by a recent investigation that showed decreased mortality, length of stay, and costs when patients were admitted to the care of a surgeon rather than the medical service, even though the majority of patients were managed nonoperatively. In fact, only a very small percentage of patients with intestinal obstruction require immediate or urgent operation upon presentation [2, 3]. Identifying which patients require immediate operative intervention is critical since delays in therapy typically result in bad outcomes for elderly patients due to their associated comorbidities and limited physiological reserve. Timely intervention in these patients can limit progression to intestinal ischemia and perforation or the need for significant bowel resection that may result in short gut, especially if the patient has already undergone prior operation with bowel resection. However, determining when to intervene in these patients is complicated due to the presence of confounding variables such as altered mental status, dementia, medications, comorbidities, as well as a blunted pain response in the elderly. Additionally, the immune system in the elderly may be less robust than that of younger patients, and the typical signs of inflammation or infection may be diminished or absent. It is these comorbidities and physiologic limitations that make timely management decisions regarding operative intervention even more critical in the elderly. These decisions are further complicated by the disastrous complications that may occur with inappropriate operative intervention making the decision to operate on the elderly obstructed patient one of the most challenging in all of general surgery. In order to assist clinicians with this decision process, some novel diagnostic technologies and clinical strategies have emerged. The success of clinical pathways in other surgical specialties and disease states is spilling over into the management of bowel obstruction in the elderly. Emerging evidence supports protocol-based management of elderly patients with intestinal obstruction, particularly in identifying which patients require exploration versus those that are best managed nonoperatively. These protocols are of particular interest to acute care surgeons since they typically are the surgeons caring for these challenging patients; thus staying abreast of recent developments is a crucial aspect of caring for these patients.

More than 20 % of emergency abdominal operations are performed for intestinal obstruction, and small bowel causes outnumber large bowel ones by a 3 to 1 ratio [4]. In elderly patients the predominant cause of intestinal obstruction is postoperative adhesions with the highest prevalence occurring in patients with previous colorectal or pelvic procedures. Incarcerated hernias and neoplasms are the next most common cause of obstruction, and it is noteworthy that adhesions and hernias remain the two most common causes of small bowel obstruction across all age groups [4]. The demographics of patients undergoing operation for intestinal obstruction continues to evolve and mirrors the aging of the US population with the peak incidence of operative obstructions occurring during the seventh decade of life [5]. In light of recent projections that over 30 % of the population will be over the age of 65 by the year 2030, it is likely that the elderly will make up the majority of patients requiring admission and operative intervention for intestinal obstruction.

Although much more rare, other causes of small bowel obstruction in the elderly include primary small bowel tumors, small bowel metastases from melanoma or direct invasion from colon cancers, Crohn’s disease, volvulus, intussusception, internal hernias, bezoars, strictures, and gallstone ileus. Primary small bowel tumors make up approximately 5 % of all gastrointestinal neoplasms, but their most common presenting sign is obstruction. This is also true for other neoplasms such as lymphoma, stromal tumors, carcinoid tumors, adenocarcinoma, and metastases [6]. Gallstone ileus occurs when a gallstone passes through a fistula between the gallbladder and duodenum and subsequently transits the small bowel ultimately impacting in the terminal ileum. This entity is rare, accounting for only 1–4 % of cases of small bowel obstruction, but when it does occur it is almost exclusively in elderly patients [7]. The typical patient suffering from gallstone ileus tends to be debilitated and have significant comorbidities which complicate their care, but the diagnosis is straightforward with the proper imaging studies and appropriate index of suspicion.

Colonic obstructions are much more prevalent in the elderly compared to younger patients. In developing nations, colonic volvulus, specifically sigmoid volvulus, is a major cause of large bowel obstructions. Many years ago this was also true in the United States, but now colonic tumors are the most common cause of large bowel obstruction as the American diet has changed from a high residual diet of roughage to a high-fat diet low in fiber. Other causes of large bowel obstruction include primary colonic tumors and inflammation or late stricture from diverticulitis, ischemic strictures, and incarcerated hernias. The sigmoid colon is the most frequent location of obstructing colon cancer, and in general cancers distal to the splenic flexure more commonly cause obstruction due to the narrower lumen of the left colon compared to the right. It is also important to consider the functional, nonmechanical etiologies of large bowel obstruction that are commonplace in patients of advanced age, especially those who are debilitated or have a history of laxative dependency. The syndrome of colonic pseudo-obstruction, or Ogilvie’s syndrome, typically occurs in elderly patients hospitalized for other reasons, and the treatment of colonic dysfunction is very different from that of mechanical causes of obstruction. Lastly, constipation and stool impaction are often causes of colonic obstruction that occurs almost exclusively in the elderly and should be considered in the differential diagnosis of obstruction.

The diagnosis of intestinal obstruction in the elderly can be challenging due to the varied nature of their chief complaints; thus it is advisable that the clinician adopt a systematic approach to the patient considering each sign and symptom separately. The most common symptom of bowel obstruction is obstipation, a prolonged period without the passage of flatus or stool. When obtaining the history of present illness from the patient or caregiver, it is important to determine when the last signs of bowel function occurred and whether this is a significant change from their baseline function. This may be difficult if the patient has a history of constipation, since new onset obstipation may be hard to differentiate in a background of slow transit time. Other commonly reported symptoms include crampy or colicky periumbilical abdominal pain that can progress to diffuse and unrelenting pain as the obstruction becomes established. This visceral pain is nearly always associated with nausea and sometimes emesis, but the lack of emesis does not rule out the presence of intestinal obstruction. Reviews of large series of patients with bowel obstruction have shown obstipation, emesis, and abdominal pain are the most commonly noted symptoms [5, 8, 9]. Generally, the more proximal the site of intestinal obstruction, the less voluminous the patient’s emesis will be, and in the case of gastric volvulus, the patient may retch but produce very little vomitus at all. More distal obstructions can lead to copious emesis since in addition to whatever food or fluid has been ingested, the gastrointestinal tract makes several liters of secretions adding to the volume of the vomitus. Feculent emesis is observed in long-standing intestinal obstruction and is the result of bacterial overgrowth proximal to the site of obstruction. Less specific symptoms such as fatigue, general malaise, and weakness are likely related to dehydration and possibly lack of nutritional intake. Patients with intestinal obstruction lose significant amounts of fluids from sensible sources such as emesis as well as insensible sources such as sequestration of edema fluid in the bowel wall and lumen. Patients with a relapsing and remitting course of symptoms that vary with oral intake likely have a partial intestinal obstruction. These patients often report a decrease in their stool production or frequency. Conversely they may complain of intermittent loose stools and may not report obstipation at all. Many of these patients will have learned to alter their diet to protect themselves from developing abdominal pain that they associate with taking certain solids, particularly roughage.

All patients with a suspected intestinal obstruction should undergo a thorough history and physical examination. It is particularly important to inquire about medical comorbidities, past surgical history, endoscopic history, and whether there have been similar prior episodes or hospital admissions for intestinal obstruction. Physical examination should be done in a comprehensive fashion with particular focus on the patient’s general appearance, behavior, and abdominal findings. Cope’s Early Diagnosis of the Acute Abdomen advocates that “one should always take the time to watch the patient quietly for several minutes” to gauge if there is an abdominal emergency [15]. Patients writhing in pain, trying to find a comforting position, or suffering bouts of emesis indicate colicky pain from distention of a hollow viscus in contrast to the ominous sign of those lying very still who may have peritonitis. The abdominal exam should be done systematically starting with inspection, followed by auscultation and palpation. Inspection allows for assessment of the degree of distention and the presence of surgical scars, a sign that the patient may have adhesive bowel disease. Distention tends to be less noticeable in more proximal obstructions such as gastric volvulus, gastric outlet obstruction, or duodenal obstructions. More distal obstructions of the small bowel due to adhesions, incarcerated hernias, cecal or sigmoid volvulus, colonic masses, and colonic pseudo-obstruction lead to marked and impressive distention due to large volumes of air and fluid that accumulate proximal to the point of obstruction. This is also why tympany upon percussion tends to present on physical examination with more distal obstructions. Auscultation can be revealing if there are classic high-pitched tinkling bowel sounds of an early obstruction but tends to be fairly insensitive and nonspecific, particularly if there are diminished sounds as seen in long-standing obstructions.

Palpation is performed to evaluate for tenderness, signs of peritoneal irritation, and guarding, and a thorough exam looking for abdominal wall or groin hernias is mandatory. Abdominal tenderness implies irritation of the peritoneal surfaces and in the early stages of obstruction is due to the apposition of a dilated viscus against the peritoneum. Involuntary guarding or signs of peritoneal irritation are worrisome and imply peritonitis. Lastly a rectal examination should be done to evaluate for impacted stool, bleeding, and masses. Patients with strangulated intestinal obstruction and bowel ischemia often have abdominal pain out of proportion to physical exam findings and warrant prompt operative exploration. Unfortunately, signs of peritonitis including abdominal guarding and rebound tenderness are of limited sensitivity and specificity and have been shown to be present in less than 50 % of patients with small bowel obstruction and strangulation [9, 10]. While nonspecific, the general appearance of patients is important to note, and very toxic-appearing patients often have peritonitis, septic shock, or advanced bowel ischemia.

The patient’s vital signs can be very helpful as the clinician formulates a differential diagnosis. Tachycardia is common and may be due to dehydration and hypovolemia, pain, or marked systemic inflammation from ischemic bowl or peritonitis. Fever may be present, and like tachycardia it has been shown in multiple reviews to have no significant correlation to the presence of dead bowel. A hallmark study in the past reviewed the records of 238 patients with small bowel obstruction focusing on the presence of the four “classical” findings of leukocytosis, tachycardia, fever, and localized tenderness. When patients had none of these present, a period of nonoperative management was appropriate and not associated with added morbidity or mortality [11]. This approach has been supported by more recent investigation and ongoing clinical experience, but there remains no formal set of symptoms or signs in intestinal obstruction that can be utilized to determine whether urgent surgery is needed. Indeed, one review of small bowel obstruction stated “identification of those at risk for bowel ischemia and bowel death is an art as much as it is a science” [13].

One of the primary decisions in the evaluation of elderly patients with suspected intestinal obstruction is to determine the urgency of the condition and whether there is a closed loop obstruction or ischemic intestine requiring immediate operation. Unfortunately retrospective analyses of elderly patients with operative findings of strangulated or compromised intestine have shown that classic clinical signs such as peritonitis or abnormal vital signs are only present in the minority of patients [12]. Accordingly, it is important to add elements of laboratory and radiologic testing to enable the clinician to increase their diagnostic acumen.

A complete blood count with differential and a basic metabolic panel should be obtained on all patients with suspected intestinal obstruction. Leukocytosis is often suggestive of generalized inflammation or infection but is too nonspecific to indicate compromised intestine. Generally, the degree of leukocytosis often correlates with the severity of the intra-abdominal process, but this is not the case in the elderly who may have mild leukocytosis or even a normal white cell count in the presence of necrotic bowel. The presence of bandemia is a worrisome sign, but this too has a low sensitivity for compromised or necrotic bowel; however, the combination of leukocytosis with significant bandemia ought to increase the index of suspicion for strangulation. Lactic acidosis may suggest ischemic bowel but can also be elevated due to dehydration. Dehydration is a common finding in patients with intestinal obstruction and is the result of fluid losses from emesis, bowel edema, and intraluminal fluid accumulation as well as decreased oral intake. Mild dehydration may result in hemoconcentration and prerenal azotemia, while the classically described hypokalemic, hypochloremic alkalosis is seen with long-standing obstruction. This results from loss of potassium followed by hydrogen ions as the kidney attempts to preserve sodium and water via the renal tubular mechanisms. This finding is seen with proximal obstructions, while distal obstructions tend to have a more unpredictable electrolyte profile. In fact patients may exhibit marked hypernatremia or hyponatremia depending on what compensatory physiologic mechanism has predominated.

Following laboratory analysis, radiologic evaluation should start with an upright chest x-ray to evaluate for free intraperitoneal air and the need for urgent exploration. Plain abdominal films obtained in the supine and upright positions assess for dilated loops of bowel, “step laddering” indicating fluid collections in the dependent portions of intestinal loops with air in the superior portion, and most importantly for the presence of air in the descending colon and rectum indicating a distal (colonic) obstruction. Air in the distal colon on radiographic studies indicates that a complete bowel obstruction is very unlikely and that a period of nonoperative management is warranted. Overall, the sensitivity and specificity of plain x-rays for diagnosing obstruction are between 50 and 80 %, while CT scan with oral and intravenous contrast has been shown to have greater than 90 % sensitivity [16]. Recent meta-analysis reveals that the CT findings indicative of bowel obstruction include proximal dilated intestine, transition point, and fecalized intestinal contents [17]. CT scan without oral or intravenous contrast has been shown to have equal sensitivity and specificity for bowel obstruction compared to contrast studies avoiding many of the complications associated with contrast administration [17]. CT scan evaluation for ischemic intestine is not quite as reliable; however sensitivity and specificity have been shown to be greater than 80 % and 90 %, respectively, with the key findings being reduced intestinal wall contrast enhancement and mesenteric attenuation [16, 17]. Not all patients need a CT scan and in some cases avoiding a scan is desirable since having a patient with intestinal obstruction lay flat may predispose them to massive aspiration and respiratory complications including death. Patients with a history of prior abdominal surgery and likely adhesive bowel obstructions can be admitted with a workup of plain x-rays since the information from a CT scan often does not change management. Interestingly, some advocate scans as potentially therapeutic for cases of partial obstruction as hyperosmolar water-soluble contrast agents may draw fluid into the bowel lumen and promote intestinal motility. The role of water-soluble contrast remains controversial in the setting of bowel obstruction since some studies have shown faster resolution of adhesive obstruction and lower rates of need for surgery, while others have shown no benefit [20–22]. Follow-up plain radiographs may be useful in patients that have undergone CT scan evaluation to assess progression of the contrast. The presence of such contrast in the colon within 24 h of administration has been shown to be 97 % sensitive and 96 % specific for resolution of adhesion-related obstruction in meta-analysis [22].

Ultrasound and MRI are additional imaging adjuncts that have some utility in the diagnosis of bowel obstruction. Ultrasound is classically used to evaluate gallbladder pathology; however there is increasing enthusiasm for its usefulness to assess obstruction. It has been shown in a few series to be as sensitive and more specific for diagnosis of obstruction when compared to plain x-rays [23–25]. The major advantages of ultrasound are its ability to be done quickly in a point of care fashion, its repeatability, and the lack of ionizing radiation exposure to the patient. Key findings suggestive of intestinal obstruction on ultrasound are bowel dilation, bowel wall thickening, presence of hypo- or hyperperistalsis, and free intra-abdominal fluid. Bowel wall thickening and free fluid may be more indicative of ischemia or perforation, but further study is needed to confirm the reliability of these findings. Ultrasound can also be used to assess inferior vena cava diameter to assess the volume status in patients with obstruction and may have a role in guiding fluid resuscitation. MRI is expensive and time consuming, and it is unwise to place an elderly patient with potential obstruction in the supine position for a prolonged period due to risk of vomiting, aspiration, and atelectasis. Other advanced imaging options to diagnose obstruction are MR fluoroscopy, CT enterography, enteroclysis, and capsule endoscopy but are beyond the scope of this discussion and are more investigational in nature at this point in time. No matter what imaging study is contemplated, it must be restated that patients with signs of peritonitis or septic shock do not require any radiologic evaluation, and in this setting radiographic imaging only delays definitive care.