Article, Surgery

Large-bowel disease presenting as small-bowel obstruction is associated with a poor prognosis

a b s t r a c t

Introduction: Small-bowel obstruction (SBO) is a common cause of admission to the surgical service. On rare oc- casions, a diagnosed SBO is actually due to large-bowel pathology combined with an incompetent ileocecal valve. The purpose of this study was to investigate this phenomenon.

Methods: We performed a retrospective medical record review of patients that were admitted with a diagnosis of SBO at University of Louisville hospital and the Veterans Affairs Hospitals in Louisville, KY, from 2006 until 2014. Results: A total of 498 patients were admitted with SBO during this time period. Forty-one patients were found to have an underlying large-bowel disease. The most common large-bowel pathologies included malignancy (51%), inflammation (15%), and infection (15%). Fifteen (43%) of these patients died during admission; 93% of these were due to either their bowel obstruction or the underlying disease state. This was significantly higher than the general population (9.4% mortality, 6% due to underlying disease).

Conclusions: Patients that present with SBO due to a large-bowel source have a much higher mortality rate than those that present with other causes. rapid identification of these patients will allow for more timely and appro- priate treatment.

Introduction

intestinal obstructions are commonly encountered by general sur- geons. Both the large and small bowel can be affected, and obstruction is most commonly due to adhesions, malignancy, or hernias. Small- bowel obstructions (SBOs) are more common than large-intestine ob- structions for several reasons. First, the smaller diameter and lack of fix- ation allow for easier obstruction from external forces. Second, the Small intestine is more commonly manipulated during surgical procedures, causing adhesive SBOs to be much more common in the small bowel compared with the colon [1]. Finally, the combination of small diameter and increased mobility also allows it to enter hernias more readily than the colon [2].

Small-bowel obstructions are classified as either low or high grade. The definitions of these terms vary in the literature, but generally a low-grade or partial obstruction is diagnosed when there are still fluid and air in the distal bowel, whereas high-grade obstruction is defined

? Funding sources: No external funding was used for this project.

?? Presentation: the Association of VA Surgeons meeting, April 21-23, 2013, in Milwaukee, WI.

* Corresponding author at: Hiram C. Polk Jr MD Department of Surgery, University of Louisville School of Medicine, 550 South Jackson St, Louisville, KY, 40292, USA. Tel.: +1 502 852 5442; fax: +1 502 287 6191.

E-mail address: [email protected] (J.L. Weaver).

as those with little to no gas in the distal bowel. High-grade obstructions include complete obstructions, which occur when both ends of the bowel are blocked [3,4]. These can be referred to as closed-loop obstruc- tions. The major morbidity and mortality associated with an SBO are due to peritonitis from intestinal ischemia, necrosis, and perforation [5,6]. Early suspicion and identification of SBOs causing ischemia are essential, as the mortality from this condition increases significantly when surgi- cal treatment is delayed in the face of perforation [7].

Obstructing colonic lesions can occasionally present as an SBO when a distal blockage associated with an incompetent ileocecal valve allows accumulation of gas and fluid in the small intestine. In the United States, large-bowel obstructions (LBOs) are most commonly due to colon can- cer, which accounts for more than half of LBOs. The vast majority of these are due to tumors distal to the splenic flexure [8,9]. Other com- mon causes of LBO include colonic volvulus (10%-17%) and Diverticular disease (10%) [9]. Initial clinical presentation for both small- and large- intestine obstruction is quite similar, as both present with abdominal pain and distention [9,10]. Therefore, definitive diagnosis is typically ac- complished with imaging studies. Typical initial imaging includes an upright chest radiograph as well as flat and upright abdominal radiographs, but it has been reported that plain radiographs are only ac- curate 46%-85% of the time [3]. computed tomographic scanning is often performed because of the reported increased accuracy of diagno- sis and identifying the Underlying etiology of obstruction. Computed

http://dx.doi.org/10.1016/j.ajem.2015.12.008 0735-6757/

478 J.L. Weaver et al. / American Journal of Emergency Medicine 34 (2016) 477–479

tomographic scan has been reported to correctly predict the level of in- testinal obstruction in up to 93% of cases [11]. Computed tomography has also been reported to correctly identify the underlying etiology in 87% of cases compared with 7% by plain radiographs [12].

Despite these improvements in imaging, cases of large-bowel pa- thology presenting as SBO are not always recognized at the time of pre- sentation. When these cases are not correctly identified, these patients may suffer recurrent admissions and nontherapeutic interventions due to lack of treatment of the underlying problem. The purpose of this study is to assess whether large-bowel pathology presenting as an SBO is associated with any specific risk factors or underlying causes, and identify any differences in outcome compared with other causes of SBO.

Methods

We performed a retrospective medical record review of all patients that were discharged from either University of Louisville hospital or the Robley Rex Veterans Affair hospital in Louisville, KY, with a diagnosis of SBO between 2006 and 2014. A total of 498 patient medical records were included in the study. Diagnosis was confirmed with either ab- dominal radiographs or CT scan. Qualifying medical records were also reviewed for demographic data, imaging, laboratory results, the pa- tients’ medical and surgical history, operative reports, and the patients’ ultimate outcome. Data were analyzed using SPSS software (IBM). This study was approved by the Institutional Review Boards of the University of Louisville and the Louisville Veterans Affair.

Results

A total of 498 patients were admitted with SBO during this time pe- riod. The diagnosis was confirmed on abdominal radiograph or CT. These patients had an average age of 58 (17-96) years, and 62% were male, likely in part due to the significant proportion of veterans in our population.

Forty-one patients were admitted with an SBO that was found to be actually due to underlying large-bowel disease. These patients were 80% male with an average age of 65 years. Thirty-eight (93%) of these pa- tients were diagnosed with a CT scan before any operative procedure, whereas 7% were diagnosed at the time of surgery. Twenty-six (63%) re- ceived at least 1 operation during that admission. A majority (51%) of these patients’ obstructions were due to a malignancy, whereas less common causes include inflammation (15%), infection (15%), hernia (5%), and volvulus (5%).

Of these patients with large-bowel pathology, 15 (37%) died during admission, compared with the overall admission mortality of 9.4%. Among those with large-bowel pathology who died, 14 (93%) were due to either the bowel obstruction itself or the underlying disease state. This was also much higher than the general population, where only 6% of deaths were due to the same causes. The most common pa- thology in the group that died of their disease was colon cancer (42%) followed by pelvic mass (21%) and Inflammatory process (14%).

Patients that had colon cancer or a mass causing their SBO had a

much higher risk of mortality during admission (Odds Ratio [OR], 17.7). Preexisting chronic renal failure or a history of coronary artery disease increased risk of mortality (OR, 1.68 and 2.29, respectively). Hy- pertension (OR, 0.69), diabetes (OR, 0.81), or a history of smoking (OR, 1.02) did not increase the risk of death. Receiving an operation did not increase mortality (OR, 0.51).

Discussion

Small-bowel obstruction accounts for 300,000 hospitalizations in the United States every year. Approximately 70%-75% of these are due to adhesions from prior surgery, with most of the rest due to hernias, in- flammatory disease, or neoplasm [13,14]. One study demonstrated that

the cost of adhesion-related complications alone within the first 5 years of surgery is $2350 after open surgery and $970 after laparoscopy [15]. Partial SBOs that are thought to be due to adhesions can frequently be treated with nasogastric decompression, intravenous fluids, and serial examinations without Early operation. Sixty-five percent to 81% of these patients will respond to medical management, and only 3%-6% will progress to strangulation [16]. Therefore, in patients who present with SBO but without signs of strangulation such as tachycardia, acido- sis, leukocytosis, or peritonitis, a trial of Conservative therapy is war- ranted. However, rapid identification and surgical treatment of patients with signs of strangulation are critical because mortality rate increases significantly with delayed diagnosis or surgery requiring bowel resection [10].

Large-bowel obstructions, on the other hand, are treated differently. Colon cancer is the most common cause of LBO in the developed world, and at least 10% present with obstruction and half of these patients al- ready have metastasis [17]. Traditional treatment of obstructing cancer includes gastrointestinal decompression with surgical resection, bypass, or diversion. However, such emergency surgery is associated with sig- nificantly increased mortality [18]. The development of endoscopic stents has allowed for safer palliative treatment or bridge to surgery [17]. Colonic volvulus is much less common and can involve the cecum, transverse, or sigmoid colon. Whereas untreated volvulus can lead to bowel strangulation, perforation, and death, early diagnosis can allow for nonoperative treatment with an endoscope [19,20]. Le- sions from diverticulitis or inflammatory bowel disease are relatively rare causes of LBO [21]. Much like SBOs, patients with LBOs and signs of strangulation or Bowel necrosis require immediate surgical interven- tion. However, the development of Endoscopic procedures has in- creased the number of available treatments for LBO, leading to improvements in morbidity and mortality. There is scant literature on LBOs that present as SBOs. The advent of routine CT scanning has more reliably distinguished between the two, which is clearly helpful if emergency Surgical decompression is required.

In our study, we identified 41 cases out of 498 SBO admissions that were primarily due to large-bowel pathology. Of these 41 cases, only 7 had a previously known history of colonic pathology, which was most commonly colon cancer. The rest of the identified patient population presented with previously undiagnosed colonic pathology that mani- fested as an SBO. Many of these conditions, such as cancer or inflamma- tory bowel disease, may have been diagnosed with a simple screening colonoscopy. The 37% mortality in these patients was much higher than that in the general SBO population, where mortality was 9.4%. Of the large-bowel pathology patients, 93% died as a result of their obstruc- tive process, compared with 6% in the general population. The reason for this is most likely due to the underlying pathology itself. This type of ob- struction is usually due to a malignant, inflammatory, or infectious pro- cess, and patients suffering from such conditions tend to be malnourished and heal poorly after surgical intervention, putting them at higher risk for anastomotic leak, Wound infection, and other se- rious complications.

What is also clear from our data is that SBO due to large-bowel pa- thology is a separate entity from an isolated SBO. If the primary large- bowel pathology goes unrecognized, this could lead to inappropriate treatment, such as obstructing colon cancer being treated with conser- vative therapy, which could delay proper diagnosis and treatment by not addressing the underlying problem. Although these cases are less common (8.2% of cases reviewed in this study), they are frequent enough that physicians must remain vigilant when diagnosing SBO. Early recognition can allow for more appropriate discussion with the patient about both the underlying diagnosis and their prognosis, allowing for either earlier appropriate surgical therapy or, in the case of advanced cancer, implementation of palliative therapy. Liberal use of CT scanning in all patients suspected of SBO, as well as use of gastrograffin enemas in those without prior operations or hernias, is useful to diagnose cases of LBO which present as SBO.

J.L. Weaver et al. / American Journal of Emergency Medicine 34 (2016) 477–479 479

Conclusions

In conclusion, large-bowel pathology presenting as an SBO is associ- ated with a significantly higher mortality than an isolated SBO. Use of CT scanning is associated with increased diagnostic accuracy in these pa- tients and is recommended so that these patients can receive rapid and appropriate treatment.

Competing interests

All authors declare that they have no competing interests.

Acknowledgments

No external funding was used for this project.

References

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