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Who Should Manage Patients with Adhesive Small Bowel Obstruction?
Advances in Surgery j (2017) j–j
ADVANCES IN SURGERY Who Should Manage Patients with Adhesive Small Bowel Obstruction? Christopher T. Aquina, MD, MPHa, Fergal J. Fleming, MDb,* a
Department of Surgery, University of Rochester Medical Center, Box SURG, 601 Elmwood Avenue, Rochester, NY 14642, USA; bDepartment of Surgery, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, NY 14642, USA
Keywords
Adhesive small bowel obstruction Primary service Admitting service Health services research
Key points
Adhesive small bowel obstruction (SBO) is a common complication after abdominal surgery and is associated with high health care utilization and cost.
Because most patients are now successfully managed nonoperatively, there has been an increase in the number of patients with adhesive SBO admitted to medical services.
Several retrospective studies have demonstrated that admission of adhesive SBO patients to a medical service is associated with a delayed time to operative intervention, longer length of stay (LOS), higher cost, and a higher operative mortality rate compared with admission to a surgical service.
Although these findings support management of adhesive SBO patients by primary surgical teams, future research should focus on identifying differences in management across providers and the impact of standardized management protocols on limiting practice variation.
Disclosure Statement: Dr F.J. Fleming received personal fees from UpToDate unrelated to the current work. Dr C.T. Aquina has nothing to disclose.
*Corresponding author. E-mail address: [email protected] http://dx.doi.org/10.1016/j.yasu.2017.03.010 0065-3411/17/ª 2017 Elsevier Inc. All rights reserved.
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INTRODUCTION There exists a feeling among physicians and students that anything over 10 years old has no pertinence.If you only look forward, it’s tantamount to having a physician with total amnesia. How good would he be? —Owen Wangensteen [1]
Until the pioneering work of Owen Wangensteen in the 1930s, bowel obstruction was nearly universally fatal. Before his publications, most surgeons believed that death from this condition was secondary to toxic factors in the bowel and their absorption into the blood stream. They attributed gaseous distention to the production of methane from bacteria acting on retained food, and patients rarely survived operative intervention. Through various experiments, however, Wangensteen demonstrated that abdominal distention was due to swallowed air and that bowel decompression using nasogastric tubes successfully treated both experimental animals and patients with bowel obstruction. Patients could then undergo an operation safely or avoid surgery altogether in many circumstances. This groundbreaking work introduced the concept of nonoperative management of adhesive SBO [1]. Adhesive disease after abdominal surgery remains the most common cause of SBO and accounts for 49% of cases of SBO [2]. Despite increases in the use of laparoscopy and some evidence that a laparoscopic approach decreases the risk of SBO [3,4], this long-term complication occurs in up to one-third of postoperative patients and accounts for 1 million inpatient hospital days and $2 billion in inpatient cost each year in the United States [5]. Given that most patients with adhesive SBO are now successfully managed nonoperatively, many patients with adhesive SBO are admitted to medical or hospitalist services rather than primary surgical services [6–9]. Given that adhesive SBO is a potential surgical emergency, however, whether all cases of adhesive SBO should be managed primarily by surgeons remains a controversial topic, and wide variation exists across hospitals regarding the choice of primary service for these patients [10]. This article reviews the current literature on differences in outcomes between primary medical and surgical services for patients admitted to the hospital with adhesive SBO and possible strategies at improving the management of these patients. HISTORICAL CONTEXT Since the introduction of nasogastric tube decompression, originally known as Wangensteen suction, successful management of adhesive SBO is most often achieved through conservative measures. In fact, 65% to 80% of patients are successfully managed without operative intervention [6–9], and, despite the adage, ‘‘the sun should never rise and set on a complete bowel obstruction,’’ [11] recent studies have demonstrated that even high-grade or complete SBO can be safely and successfully managed with nonoperative management in 41% to 73% of patients [7,9,12]. This high success rate is largely in part to
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previous studies demonstrating clinical signs associated with bowel ischemia and the advancement of CT imaging. Clinical signs, such as the presence of peritonitis, continuous pain, fever, tachycardia, leukocytosis, metabolic acidosis, and the systemic inflammatory response syndrome, can predict bowel ischemia in 40% to 50% of cases (Fig. 1) [13–16]. The addition of imaging findings to clinical factors further improves the accuracy of identifying patients with bowel ischemia to 70% to 96% [17–19]. Historically, surgical services have admitted patients with adhesive SBO because the condition has been considered a surgical disease. With an increasing proportion of patients managed without surgery, however, there has been a shift in the paradigm of who primarily manages these patients while they are in the hospital. Unless patients have a clear indication for urgent surgical intervention, many patients with adhesive SBO are admitted to a primary medical service with consultation from a general surgeon. In 1 recent population-based study, 42% of patients with adhesive SBO were managed by a primary medical team [10]. In addition, the choice of primary service seems dependent on individual institutional practices because rate of admission to a primary medical service ranged from 0.2% to 95.3% across hospitals even after controlling for patient demographics and comorbidities, primary attending characteristics, and hospital factors [10].
Fig. 1. Bowel necrosis secondary to SBO. (From Zielinski MD, Bannon MP. Current management of small bowel obstruction. Adv Surg 2011;45:7; with permission.)
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DOES ADMITTING SERVICE MATTER? A REVIEW OF THE LITERATURE To date, there have been 5 retrospective cohort studies directly investigating the impact of the primary service on outcomes for SBO [10,20–23]. In this section, study findings related to the relationship between admitting service (surgical service vs medical service) and various outcomes across each of the studies are discussed (Table 1); 4 of the 5 studies had heterogeneous study cohorts consisting of patients with various etiologies for the SBO. Although adhesions were the most common cause of SBO in each of the studies, 3 of the studies also included patients with cancer, hernias, inflammatory bowel disease, volvulus, or other causes of obstruction [20,21,23], and 1 of the studies did not report the causes of SBO [22]. Time to surgery Various studies have demonstrated a relationship between delayed time to surgery and worse outcomes for adhesive SBO [11,24,25]. As a result, the relationship between primary service and number of days from admission to surgery was an endpoint in each of the 5 studies. Among 217 admissions, Malangoni and colleagues [20] demonstrated that admission to a medical service was associated with an increase in mean time to surgery of approximately 4 days compared with admission to a surgical service (6.3 vs 2.7 days; P ¼ .007). Similarly, Schwab and colleagues [21] observed a 2-day longer median time to surgery (3 days vs 1 day; P ¼ .003) across 65 patients, Oyasiji and colleagues [22] found a longer time to surgery (log-rank test; P ¼ .006) among 244 patients, Bilderback and colleagues [23] observed an approximately 2-day longer median time to surgery (51.7 hours vs 8.4 hours; P<.0001) across 130 patients, and Aquina and colleagues [10] found an 84% increase in days to surgery (incidence rate ratio [IRR] ¼ 1.84; 95% CI, 1.69, 2.01) among 23,913 admissions when comparing a primary medical service to a primary surgical service. Although time to surgery was significantly longer for patients admitted to a medical service in each of the 5 studies, this finding may be partially explained by selection bias as to which patients are admitted to a medical service compared with a surgical service. Patients admitted to a medical service were more likely to have a higher comorbidity burden [10,22,23] which would increase operative risk and favor longer nonoperative management and were less likely to have clinical signs concerning for high-grade obstruction or bowel ischemia [20], which may promote earlier surgical intervention. In addition, only 2 of the studies controlled for case mix in the analyses [10,23]. In a sensitivity analysis by Aquina and colleagues [10], however, that included 17,511 patients, a primary medical service was still independently associated with longer time to surgery (IRR ¼ 1.45; 95% CI, 1.38, 1.53) after controlling for patient age and comorbidities and excluding those who underwent operative intervention within 24 hours of admission.
Table 1 Current studies comparing outcomes for adhesive small bowel obstruction between a primary surgical service and a primary medical service Number of Author, year admissions Type of study Years
Study outcomes
Malangoni 336 et al [20], 2001
Retrospective, 1992– single 1998 institution
Schwab 65 et al [21], 2001a
Retrospective, 1997– single 2000 institution
Oyasiji 635 et al [22], 2010b
Retrospective, 2003– single 2007 institution
Bilderback 555 et al [23], 2015
Retrospective, 2008– single 2012 institution
Aquina 107,603 et al [10], 2016
Retrospective, 2002– population2013 based (New York State)
a b
Time to surgery LOS Days to tolerating a regular diet
Time to surgery LOS Bowel resection 30-d morbidity 30-d mortality
Time to surgery LOS Hospital charges Bowel resection Mortality
Time to surgery LOS 30-d morbidity Hospital charges 30-d readmission
Time to surgery LOS Hospital cost Small bowel resection 30-d readmission 30-d mortality
Study only included operative cases. No analysis for the nonoperative subgroup was performed.
Significant findings (medical service vs surgical service) Nonoperative group Shorter LOS Shorter time to tolerating a regular diet Operative group Longer time to surgery Longer LOS Operative group Longer time to surgery Longer LOS Higher morbidity rate Higher mortality rate Overall Longer LOS Lower bowel resection rate Operative group Longer time to surgery Longer LOS Higher hospital charges Nonoperative group No differences Operative group Longer time to surgery Longer LOS Higher hospital charges Nonoperative group Longer LOS Higher hospital cost Higher readmission rate Operative group Longer time to surgery Longer LOS Higher hospital cost Higher mortality rate
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Length of stay The relationship between admitting service and LOS was evaluated in each of the 5 studies. Although each of the studies compared LOS after operative intervention [10,20–23], only 3 of the studies evaluated LOS after nonoperative management [10,20,23]. In the study by Oyasiji and colleagues [22] that grouped nonoperative and operative management together into 1 analysis, the investigators observed longer LOS for medical services (7.5 vs 6.1 days; P ¼ .01) compared with surgical services. Nonoperative management The studies had conflicting findings regarding LOS after nonoperative management. Among 119 admissions for SBO, Malangoni and colleagues [20] observed a shorter LOS (4.8 vs 7.2 days; P ¼ .02) for patients admitted to a medical service. The investigators also found that patients admitted to a medical service had a shorter time to diet resumption (3.1 days vs 4.3 days; P ¼ .03) [20]. In contrast, Aquina and colleagues [10] found that patients admitted to a medical service had an approximately 40% increase in LOS (IRR ¼ 1.39; 95% CI, 1.24, 1.56) after controlling for case mix among 83,690 admissions for adhesive SBO. Bilderback and colleagues [23] found no significant difference in LOS between admitting services across 425 admissions. Operative management There were more consistent findings across studies with respect to LOS after operative management. Each of the 4 studies demonstrated longer LOS for patients admitted to medical services. Malangoni and colleagues [20] observed an approximately 5-day difference in mean overall LOS (22.8 days vs 17.9 days; P<.0001), Schwab and colleagues [21] found a 5-day difference in median LOS (13 days vs 8 days; P ¼ .02) , Oyasiji and colleagues [22] observed a 3-day difference in mean LOS (12.3 days vs 9.1 days; P ¼ .02), Bilderback and colleagues [23] demonstrated an approximately 3-day difference in median LOS (9.57 days vs 6.99 days; P ¼ .002), and Aquina and colleagues [10] observed a 36% increase in LOS (IRR ¼ 1.36; 95% CI, 1.25, 1.49) when comparing a primary medical service to a primary surgical service. Again, some of the differences in LOS may be explained by higher comorbidity burden among patients admitted to a medical service. The study by Aquina and colleagues [10], however, controlled for case mix. Hospital cost Three of the studies compared either hospital charges or costs across admitting services [10,22,23]. Oyasiji and colleagues [22] ($62,778 vs $46,258; P ¼ .05) and Bilderback and colleagues [23] ($38,800 vs $30,100; P ¼ .02) observed that medical services had higher hospital charges compared with surgical services for the operative subgroups. There was no significant difference in hospital charges between admitting services after nonoperative management in Bilderback and colleagues’ study [23]. Aquina and colleagues [10] observed significantly higher hospital costs accrued for medical services for both the
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nonoperative (IRR ¼ 1.38; 95% CI, 1.21, 1.57) and operative (IRR ¼ 1.38; 95% CI, 1.11, 1.71) subgroups. Bowel resection Three of the studies compared the rate of bowel resection across admitting services [10,21,22]. Oyasiji and colleagues [22] observed a lower rate of bowel resection for patients admitted to a medical service (5.2% vs 13.1%; P ¼ .007) across the entire study cohort. There was no significant difference, however, in the rate of bowel resection between admitting services within the operative subgroup (23%vs 30%; P ¼ .44). There was no significant difference in the rate of bowel resection between primary medical services and primary surgical services in the Schwab and colleagues [21] (45.5% vs 34.9%; P ¼ .43) and Aquina and colleagues [10] (odds ratio [OR] ¼ 1.04; 95% CI, 0.90, 1.19) studies. Time to surgery was independently associated, however, with higher odds of small bowel resection (OR ¼ 1.02; 95% CI, 1.02, 1.03) in the Aquina and colleagues [10] study as well as in previous studies, suggesting that admission to a medical service may indirectly increase the rate of small bowel resection through a delay in surgical intervention [11,24]. Thirty-day readmission Two of the studies compared the rate of 30-day readmission between admitting services [10,23]. Bilderback and colleagues [23] did not observe any significant differences in readmission rates between medical and surgical services across the nonoperative (5.1% vs 13.7%; P ¼ .11) and operative subgroups (12.3% vs 22.7%; P ¼ .09). Aquina and colleagues [10], however, did observe differences between the primary services. After nonoperative management, primary medical services were independently associated with an approximately 40% higher odds of unscheduled 30-day readmission (OR ¼ 1.39; 95% CI, 1.29, 1.50). Although not quite reaching statistical significance, medical services had a 13% higher odds of readmission (OR ¼ 1.13; 95% CI, 0.97, 1.32) compared with surgical services. Operative morbidity Two of the studies investigated 30-day morbidity rates after operative intervention [21,23]. Patients had a significantly higher rate of morbidity if admitted to a medical service (45.5% vs 11.6%, P ¼ .004) in the study by Schwab and colleagues [21]. Bilderback and colleagues [23], however, observed no difference in the complication rates between medical and surgical services (30.4% vs 27.5%; P ¼ .87) . Operative mortality Three of the studies compared mortality rates between admitting services after operative intervention with fairly consistent results [10,21,22]. Although not statistically significant, Oyasiji and colleagues [22] observed a higher mortality rate for medical services compared with surgical services (11.8% vs 3.8%; P ¼ .07). Schwab and colleagues [21] found a significantly higher 30-day mortality rate for patients admitted to a medical service (27.3% vs 2.3%; P ¼ .005),
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and Aquina and colleagues [10] observed that a primary medical service was independently associated with an approximately 2-fold higher odds of 30-day mortality compared with a primary surgical service (OR ¼ 1.92; 95% CI, 1.50, 2.47). KEYS TO IMPROVING OUTCOMES Possible explanations for differences in outcomes across admitting services The 5 studies, discussed previously, showed significant differences in outcomes between medical and surgical services. The studies demonstrated that admission to a medical service was associated with a delayed time to surgery, longer LOS, higher hospital cost, and higher operative mortality compared with admission to a primary surgical service. Therefore, these findings support policies favoring admission to a surgical service. These studies, however, did not evaluate possible reasons for this disparity in outcomes. Nonetheless, there are several possible explanations for these differences. With respect to nonoperative management, variation in the timing and duration of nasogastric tube decompression and timing, type, and number of radiologic images obtained may explain some of the differences between primary medical and surgical services. Although there are currently no standardized algorithms or protocols in the nonoperative management of adhesive SBO, Wangensteen outlined several criteria for removal of the nasogastric tube in his book, The Therapeutic Problem in Bowel Obstruction: A Physiologic and Clinical Consideration [26]. The criteria included cessation of ‘‘gas pains,’’ a decrease of abdominal distention, visualization of colonic gas on radiologic examination in the setting of complete obstruction, less fluid output from the nasogastric tube, and toleration of temporary discontinuation of nasogastric suction without pain [1,26]. These clinical markers are still the most commonly used indicators to guide nasogastric tube management, but variation may exist across providers. In addition, the use of contrast CT imaging not only has been shown to aid in diagnosing bowel ischemia but also may be therapeutic in cases of partial SBO. Water-soluble contrast results in shifts of fluid into the intestinal lumen and a resulting increase in the pressure gradient across the site of obstruction, which may hasten return of bowel function and reduce LOS [27–29]. Therefore, variation in the timing, type, and number of radiologic images across primary services may affect LOS and cost for patients who undergo nonoperative management. One possible explanation for differences in operative outcomes is a delay or failure to recognize signs of bowel ischemia with a concomitant postponement in surgical consultation for patients admitted to a medical service. Treatment delay is associated with a higher risk of bowel resection [10,11,24], higher morbidity [30,31], longer LOS [10,25,30], higher hospital cost [10], and a higher rate of postoperative mortality [10,25,31]. Less familiarity or experience in managing patients with adhesive SBO by medicine providers and subsequent failure in promptly recognizing worrisome clinical findings, such as
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leukocytosis, fever, tachycardia, and localized tenderness, may lead to a delay in surgical intervention and lead to worse outcomes [10,13]. Another possible explanation for the disparity in operative mortality is a difference in the rate of failure to rescue between admitting services. Recent studies have demonstrated that variation in postoperative mortality rates across hospitals are not due to differences in complication rates but are a result of differences in failure to rescue, or how well patients are managed and rescued from a complication [32–34]. Again, less experience in managing postoperative patients may explain differences in failure to rescue rates across admitting providers. This hypothesis is supported by studies suggesting that higher surgeon and hospital volume, which is a proxy for experience and scope of practice, is associated with lower failure to rescue rates [34–37]. Standardization of management Given the likely wide variation in management of patients with adhesive SBO across provider teams, standardizing management by following best-practice guidelines would likely reduce the disparity between admitting services and improve outcomes. The Eastern Association for the Surgery of Trauma (EAST) published updated evidence-based guidelines for the evaluation and management of SBO in 2012 (Table 2) [27]. In the diagnosis and evaluation of SBO, water-soluble contrast CT imaging is recommended to diagnose obstruction (accuracy ¼ 83%–94%), determine the level of obstruction (accuracy ¼ 93%), identify the cause of obstruction (accuracy ¼ 80%–91%), and detect bowel ischemia (sensitivity 85%–100%) or small bowel volvulus (Box 1) [27,38–45]. Furthermore, multiplanar CT reconstruction can further identify transition points and the site of obstruction (Fig. 2) [46]. In the management of SBO, patients with clinical factors or imaging results concerning for bowel ischemia should undergo early operative exploration. Those without these concerning factors can safely undergo initial nonoperative management irrespective of the grade of obstruction [7,9,12]. For those who do not have resolution, a water-soluble contrast study should be considered at 48 hours due to its diagnostic and therapeutic benefits [27–29]. Finally, patients without resolution by days 3 to 5 should either undergo a water-soluble contrast study or operative intervention [6,25]. Admission paradigms Given the findings of the studies, discussed previously, EAST recommends that patients with SBO generally be admitted to a surgical service [27]. Wide institutional variation currently exists with respect to the choice of admitting service [10]. In addition, the implementation of institutional protocols may help reduce the time to surgery and reduce LOS for patients admitted to a medical service. In a study by Wahl and colleagues [47], including 730 SBO admissions from 2010 to 2011, the investigators tracked outcomes at a single institution after implementation of an SBO triage and initial management guidelines (Box 2). After application of the paradigm, there was a decrease in the time to general surgery consultation (3.4 days vs 1.7 days; P<.001), shorter
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Table 2 Recommendations from the 2012 Eastern Association for the Surgery of Trauma practice management guideline for small bowel obstruction Recommendation Diagnosis 1. CT scan of the abdomen and pelvis should be considered in all patients with SBO. 2. Water-soluble contrast study should be considered in patients who fail to improve after 48 h of nonoperative management. 3. Multidetector CT scanner and multiplanar reconstruction should be used if available. 4. MRI and ultrasound are possible alternative imaging modalities to CT. 5. CT scan should be considered to help diagnose small bowel volvulus. Management 1. Patients with generalized peritonitis or other evidence of clinical deterioration (fever, leukocytosis, tachycardia, metabolic acidosis, and continuous pain) should undergo timely surgical exploration. 2. Patients without evidence of clinical deterioration can safely undergo initial nonoperative management. 3. CT findings consistent with bowel ischemia should suggest a low threshold for operative intervention. 4. Laparoscopic treatment of SBO is a viable alternative to laparotomy in selected cases. 5. Water-soluble contrast should be considered for patients with partial SBO that has not resolved in 48 h. 6. Patients without resolution of the SBO after 3–5 d of nonoperative management should undergo water-soluble contrast study or surgery. 7. Patients with SBO should generally be admitted to a surgical service.
Recommendation levela Level 1 Level 2 Level 3 Level 3 Level 3 Level 1
Level 1 Level 2 Level 2 Level 2 Level 3 Level 3
a
Level 1: this recommendation is convincingly justifiable based on the available scientific information alone. Level 2: this recommendation is reasonably justifiable by available scientific evidence and strongly supported by expert critical care opinion. Level 3: this recommendation is supported by available data, but adequate scientific evidence is lacking. Adapted from Maung AA, Johnson DC, Piper GL, et al. Evaluation and management of small-bowel obstruction: An Eastern Association for the Surgery of Trauma practice management guideline. J Trauma Acute Care Surg 2012; 73(5):S363; with permission.
time from admission to surgery (0.9 days vs 0.4 days; P<.05), and a decrease in LOS (8 days vs 6 days; P<.001) for patients admitted to a medical service. These findings suggest that the utilization of admission guidelines and standardization of care can improve outcomes for primary medical services. Despite improvements in these outcomes for medical services, however, surgical services still had shorter time to operative intervention and LOS compared with medical services in the study. Medical comanagement Although evidence from previous studies suggests that patients may have better outcomes if primarily managed by a surgical service, these findings do not preclude the comanagement of complex patients with multiple comorbidities by
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Box 1: List of CT findings for bowel ischemia 1. Bowel wall thickening (>3 mm) 2. Mesenteric edema 3. Fluid in mesentery and/or peritoneal cavity 4. Abnormal bowel wall enhancement, either increased or decreased 5. Occlusion of mesenteric vessels 6. Engorged mesenteric veins 7. Whirl sign 8. Closed loop obstruction or volvulus 9. Pneumatosis 10. Mesenteric venous gas 11. Portal venous gas From Paulson EK, Thompson WM. Review of small-bowel obstruction: The diagnosis and when to worry. Radiology 2015; 275(2):340; with permission.
Fig. 2. Coronal image from contrast-enhanced CT scan demonstrating a small bowel feces sign (small arrows) proximal to the transition point (large arrow) of an adhesive SBO. (From Paulson EK, Thompson WM. Review of small-bowel obstruction: The diagnosis and when to worry. Radiology 2015; 275(2):337; with permission.)
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Box 2: Example of a published institutional triage and management guideline for small bowel obstruction Evaluation 1. Patients with symptoms consistent with possible SBO should have the following: a. Complete physical examination, including a digital rectal examination and gynecologic examination if appropriate b. Acute abdominal series c. Complete blood cell count, comprehensive panel, lactate, and urinalysis 2. CT scan is not required for all patients, but if the history, physical examination, and initial imaging are supportive of a possible bowel obstruction and there is no absolute indication for an emergent surgical consultation (free air, peritonitis, nonreducible symptomatic hernia, or abdominal surgery in the last 30 days), then an abdominal CT with intravenous and oral contrast should be performed unless there is a contraindication to the study. The study can be done without intravenous contrast for those with contrast allergy or high creatinine. Relative contraindications to CT imaging may include multiple recent studies or recent surgery and reimaging should then be left to the discretion of the care providers. Initial treatment 3. Initial therapy for all patients diagnosed with complete or high-grade partial bowel obstructions should be a. Placement of an 18F nasogastric tube on continuous suction b. Intravenous fluid with nothing-by-mouth status c. Careful monitoring of urine output d. Serial abdominal examinations e. Early general surgery consultation to determine need for operative management 4. Initial therapy for partial SBO patients should include a. Placement of a nasogastric tube on continuous suction if ongoing vomiting b. Intravenous fluid with nothing-by-mouth status c. Careful monitoring of urine output d. Serial abdominal examinations e. General surgery consultation if no improvement in 48 hours or with change or worsening of the patient’s condition or abdominal examination Admission 5. If a transition point is identified on CT or a patient is deemed an emergent operative candidate or a patient has had an abdominal surgery within the past 30 days, the patient is admitted to a surgical service. Exceptions that may warrant a medical service admission could be a. Patients with intra-abdominal metastases b. Patients with active inflammatory bowel disease who are to have a trial of systemic therapy
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c. Acute, severe medical conditions requiring stabilization (ie, acute myocardial infarction, and severe exacerbation of chronic obstructive pulmonary disease) 6. Patients with known dilated bowel secondary to dysmotility problems or other medical conditions can be admitted to medicine. Examples of this include a. Chronic narcotic-induced obstipation b. Dysmotility or constipation from chronic psychotropic use or mental/developmental disorders c. Cystic fibrosis patients d. Collagen vascular diseases with bowel involvement From Wahl WL, Wong SL, Sonnenday CJ, et al. Implementation of a small bowel obstruction guideline improves hospital efficiency. Surgery 2012;152(4):627; with permission.
hospitalists. Although there are currently no studies including the population of patients with adhesive SBO, evidence from the orthopedic surgery literature suggests that involvement of hospitalists improves outcomes. In a study by Phy and colleagues [48], the investigators observed that the use of a hospitalist comanagement model decreased time to surgery and shortened LOS for older patients with a hip fracture. Furthermore, a randomized controlled trial demonstrated that a hospitalist-orthopedic team model reduced minor complications and resulted in higher satisfaction among nurses and surgeons after elective hip and knee arthroplasty [49]. The introduction of similar hospitalist comanagement models may improve outcomes for adhesive SBO patients with high comorbidity burden. SUMMARY Through the work of Wangensteen and recent advancements in radiologic imaging, there has been an increasing trend toward nonoperative management. As a result, wide institutional variation currently exists with respect to the admitting service for patients with adhesive SBO. Current studies, however, support primary management of SBO by surgeons because admission to medical services is associated with a delayed time to operative intervention, longer LOS, higher cost, and a higher operative mortality rate. Future studies should focus on variation in the management of adhesive SBO across providers, the effect of standardized management protocols in limiting this variation, and the impact of hospitalist comanagement models on outcomes for patients with a higher comorbidity burden. References [1] Faryniuk A, MacDonald A, van Boxel P. Amnesia in modern surgery: revisiting Wangensteen’s landmark studies of small bowel obstruction. Can J Surg 2015;58(2):83–4. [2] Mucha P Jr. Small intestinal obstruction. Surg Clin North Am 1987;67(3):597–620. [3] Simorov A, Shaligram A, Shostrom V, et al. Laparoscopic colon resection trends in utilization and rate of conversion to open procedure: a national database review of academic medical centers. Ann Surg 2012;256(3):462–8.
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[4] Aquina CT, Probst CP, Becerra AZ, et al. Missed opportunity: laparoscopic colorectal resection is associated with lower incidence of small bowel obstruction compared to an open approach. Ann Surg 2016;264(1):127–34. [5] Sikirica V, Bapat B, Candrilli SD, et al. The inpatient burden of abdominal and gynecological adhesiolysis in the US. BMC Surg 2011;11:13. [6] Cox MR, Gunn IF, Eastman MC, et al. The safety and duration of non-operative treatment for adhesive small bowel obstruction. Aust N Z J Surg 1993;63(5):367–71. [7] Seror D, Feigin E, Szold A, et al. How conservatively can postoperative small bowel obstruction be treated? Am J Surg 1993;165(1):121–5 [discussion: 125–6]. [8] Jeong WK, Lim SB, Choi HS, et al. Conservative management of adhesive small bowel obstructions in patients previously operated on for primary colorectal cancer. J Gastrointest Surg 2008;12(5):926–32. [9] Tanaka S, Yamamoto T, Kubota D, et al. Predictive factors for surgical indication in adhesive small bowel obstruction. Am J Surg 2008;196(1):23–7. [10] Aquina CT, Becerra AZ, Probst CP, et al. Patients with adhesive small bowel obstruction should be primarily managed by a surgical team. Ann Surg 2016;264(3):437–47. [11] Silen W, Hein MF, Goldman L. Strangulation obstruction of the small intestine. Arch Surg 1962;85:121–9. [12] Fevang BT, Jensen D, Fevang J, et al. Upper gastrointestinal contrast study in the management of small bowel obstruction–a prospective randomised study. Eur J Surg 2000;166(1):39–43. [13] Stewardson RH, Bombeck CT, Nyhus LM. Critical operative management of small bowel obstruction. Ann Surg 1978;187(2):189–93. [14] Fevang BT, Jensen D, Svanes K, et al. Early operation or conservative management of patients with small bowel obstruction? Eur J Surg 2002;168(8–9):475–81. [15] Tsumura H, Ichikawa T, Hiyama E, et al. Systemic inflammatory response syndrome (SIRS) as a predictor of strangulated small bowel obstruction. Hepatogastroenterology 2004;51(59):1393–6. [16] Takeuchi K, Tsuzuki Y, Ando T, et al. Clinical studies of strangulating small bowel obstruction. Am Surg 2004;70(1):40–4. [17] Zielinski MD, Eiken PW, Bannon MP, et al. Small bowel obstruction-who needs an operation? A multivariate prediction model. World J Surg 2010;34(5):910–9. [18] Zielinski MD, Eiken PW, Heller SF, et al. Prospective, observational validation of a multivariate small-bowel obstruction model to predict the need for operative intervention. J Am Coll Surg 2011;212(6):1068–76. [19] Kim JH, Ha HK, Kim JK, et al. Usefulness of known computed tomography and clinical criteria for diagnosing strangulation in small-bowel obstruction: analysis of true and false interpretation groups in computed tomography. World J Surg 2004;28(1):63–8. [20] Malangoni MA, Times ML, Kozik D, et al. Admitting service influences the outcomes of patients with small bowel obstruction. Surgery 2001;130(4):706–11 [discussion: 711–3]. [21] Schwab DP, Blackhurst DW, Sticca RP. Operative acute small bowel obstruction: admitting service impacts outcome. Am Surg 2001;67(11):1034–8 [discussion: 1038–40]. [22] Oyasiji T, Angelo S, Kyriakides TC, et al. Small bowel obstruction: outcome and cost implications of admitting service. Am Surg 2010;76(7):687–91. [23] Bilderback PA, Massman JD 3rd, Smith RK, et al. Small bowel obstruction is a surgical disease: patients with adhesive small bowel obstruction requiring operation have more costeffective care when admitted to a surgical service. J Am Coll Surg 2015;221(1):7–13. [24] Bickell NA, Federman AD, Aufses AH Jr. Influence of time on risk of bowel resection in complete small bowel obstruction. J Am Coll Surg 2005;201(6):847–54. [25] Schraufnagel D, Rajaee S, Millham FH. How many sunsets? Timing of surgery in adhesive small bowel obstruction: a study of the Nationwide Inpatient Sample. J Trauma Acute Care Surg 2013;74(1):181–7 [discussion: 187–9].
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[26] Wangensteen OH. The therapeutic problem in bowel obstructions; a physiological and clinical consideration. Springfield (IL): C.C. Thomas; 1937. [27] Maung AA, Johnson DC, Piper GL, et al. Evaluation and management of small-bowel obstruction: an Eastern Association for the Surgery of Trauma practice management guideline. J Trauma Acute Care Surg 2012;73(5 Suppl 4):S362–9. [28] Assalia A, Schein M, Kopelman D, et al. Therapeutic effect of oral Gastrografin in adhesive, partial small-bowel obstruction: a prospective randomized trial. Surgery 1994;115(4): 433–7. [29] Choi HK, Chu KW, Law WL. Therapeutic value of gastrografin in adhesive small bowel obstruction after unsuccessful conservative treatment: a prospective randomized trial. Ann Surg 2002;236(1):1–6. [30] Fevang BT, Fevang JM, Soreide O, et al. Delay in operative treatment among patients with small bowel obstruction. Scand J Surg 2003;92(2):131–7. [31] Fevang BT, Fevang J, Stangeland L, et al. Complications and death after surgical treatment of small bowel obstruction: A 35-year institutional experience. Ann Surg 2000;231(4): 529–37. [32] Ghaferi AA, Birkmeyer JD, Dimick JB. Complications, failure to rescue, and mortality with major inpatient surgery in medicare patients. Ann Surg 2009;250(6):1029–34. [33] Ghaferi AA, Osborne NH, Birkmeyer JD, et al. Hospital characteristics associated with failure to rescue from complications after pancreatectomy. J Am Coll Surg 2010;211(3): 325–30. [34] Ghaferi AA, Birkmeyer JD, Dimick JB. Hospital volume and failure to rescue with high-risk surgery. Med Care 2011;49(12):1076–81. [35] Aquina CT, Probst CP, Becerra AZ, et al. The impact of surgeon volume on colostomy reversal outcomes after Hartmann’s procedure for diverticulitis. Surgery 2016;160(5): 1309–17. [36] Mulvey CL, Pronovost PJ, Gourin CG. Hospital volume and failure to rescue after head and neck cancer surgery. Otolaryngol Head Neck Surg 2015;152(5):783–9. [37] Amini N, Spolverato G, Kim Y, et al. Trends in Hospital Volume and Failure to Rescue for Pancreatic Surgery. J Gastrointest Surg 2015;19(9):1581–92. [38] Paulson EK, Thompson WM. Review of small-bowel obstruction: the diagnosis and when to worry. Radiology 2015;275(2):332–42. [39] Suri S, Gupta S, Sudhakar PJ, et al. Comparative evaluation of plain films, ultrasound and CT in the diagnosis of intestinal obstruction. Acta Radiol 1999;40(4):422–8. [40] Obuz F, Terzi C, Sokmen S, et al. The efficacy of helical CT in the diagnosis of small bowel obstruction. Eur J Radiol 2003;48(3):299–304. [41] Daneshmand S, Hedley CG, Stain SC. The utility and reliability of computed tomography scan in the diagnosis of small bowel obstruction. Am Surg 1999;65(10):922–6. [42] Makita O, Ikushima I, Matsumoto N, et al. CT differentiation between necrotic and nonnecrotic small bowel in closed loop and strangulating obstruction. Abdom Imaging 1999;24(2):120–4. [43] Kato K, Mizunuma K, Sugiyama M, et al. Interobserver agreement on the diagnosis of bowel ischemia: assessment using dynamic computed tomography of small bowel obstruction. Jpn J Radiol 2010;28(10):727–32. [44] Zalcman M, Sy M, Donckier V, et al. Helical CT signs in the diagnosis of intestinal ischemia in small-bowel obstruction. AJR Am J Roentgenol 2000;175(6):1601–7. [45] Sandhu PS, Joe BN, Coakley FV, et al. Bowel transition points: multiplicity and posterior location at CT are associated with small-bowel volvulus. Radiology 2007;245(1):160–7. [46] Shah ZK, Uppot RN, Wargo JA, et al. Small bowel obstruction: the value of coronal reformatted images from 16-multidetector computed tomography–a clinicoradiological perspective. J Comput Assist Tomogr 2008;32(1):23–31.
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[47] Wahl WL, Wong SL, Sonnenday CJ, et al. Implementation of a small bowel obstruction guideline improves hospital efficiency. Surgery 2012;152(4):626–32 [discussion: 632–4]. [48] Phy MP, Vanness DJ, Melton LJ 3rd, et al. Effects of a hospitalist model on elderly patients with hip fracture. Arch Intern Med 2005;165(7):796–801. [49] Huddleston JM, Long KH, Naessens JM, et al. Medical and surgical comanagement after elective hip and knee arthroplasty: a randomized, controlled trial. Ann Intern Med 2004;141(1):28–38.
ADVANCES IN SURGERY Who Should Manage Patients with Adhesive Small Bowel Obstruction? Christopher T. Aquina, MD, MPHa, Fergal J. Fleming, MDb,* a
Department of Surgery, University of Rochester Medical Center, Box SURG, 601 Elmwood Avenue, Rochester, NY 14642, USA; bDepartment of Surgery, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, NY 14642, USA
Keywords
Adhesive small bowel obstruction Primary service Admitting service Health services research
Key points
Adhesive small bowel obstruction (SBO) is a common complication after abdominal surgery and is associated with high health care utilization and cost.
Because most patients are now successfully managed nonoperatively, there has been an increase in the number of patients with adhesive SBO admitted to medical services.
Several retrospective studies have demonstrated that admission of adhesive SBO patients to a medical service is associated with a delayed time to operative intervention, longer length of stay (LOS), higher cost, and a higher operative mortality rate compared with admission to a surgical service.
Although these findings support management of adhesive SBO patients by primary surgical teams, future research should focus on identifying differences in management across providers and the impact of standardized management protocols on limiting practice variation.
Disclosure Statement: Dr F.J. Fleming received personal fees from UpToDate unrelated to the current work. Dr C.T. Aquina has nothing to disclose.
*Corresponding author. E-mail address: [email protected] http://dx.doi.org/10.1016/j.yasu.2017.03.010 0065-3411/17/ª 2017 Elsevier Inc. All rights reserved.
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INTRODUCTION There exists a feeling among physicians and students that anything over 10 years old has no pertinence.If you only look forward, it’s tantamount to having a physician with total amnesia. How good would he be? —Owen Wangensteen [1]
Until the pioneering work of Owen Wangensteen in the 1930s, bowel obstruction was nearly universally fatal. Before his publications, most surgeons believed that death from this condition was secondary to toxic factors in the bowel and their absorption into the blood stream. They attributed gaseous distention to the production of methane from bacteria acting on retained food, and patients rarely survived operative intervention. Through various experiments, however, Wangensteen demonstrated that abdominal distention was due to swallowed air and that bowel decompression using nasogastric tubes successfully treated both experimental animals and patients with bowel obstruction. Patients could then undergo an operation safely or avoid surgery altogether in many circumstances. This groundbreaking work introduced the concept of nonoperative management of adhesive SBO [1]. Adhesive disease after abdominal surgery remains the most common cause of SBO and accounts for 49% of cases of SBO [2]. Despite increases in the use of laparoscopy and some evidence that a laparoscopic approach decreases the risk of SBO [3,4], this long-term complication occurs in up to one-third of postoperative patients and accounts for 1 million inpatient hospital days and $2 billion in inpatient cost each year in the United States [5]. Given that most patients with adhesive SBO are now successfully managed nonoperatively, many patients with adhesive SBO are admitted to medical or hospitalist services rather than primary surgical services [6–9]. Given that adhesive SBO is a potential surgical emergency, however, whether all cases of adhesive SBO should be managed primarily by surgeons remains a controversial topic, and wide variation exists across hospitals regarding the choice of primary service for these patients [10]. This article reviews the current literature on differences in outcomes between primary medical and surgical services for patients admitted to the hospital with adhesive SBO and possible strategies at improving the management of these patients. HISTORICAL CONTEXT Since the introduction of nasogastric tube decompression, originally known as Wangensteen suction, successful management of adhesive SBO is most often achieved through conservative measures. In fact, 65% to 80% of patients are successfully managed without operative intervention [6–9], and, despite the adage, ‘‘the sun should never rise and set on a complete bowel obstruction,’’ [11] recent studies have demonstrated that even high-grade or complete SBO can be safely and successfully managed with nonoperative management in 41% to 73% of patients [7,9,12]. This high success rate is largely in part to
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previous studies demonstrating clinical signs associated with bowel ischemia and the advancement of CT imaging. Clinical signs, such as the presence of peritonitis, continuous pain, fever, tachycardia, leukocytosis, metabolic acidosis, and the systemic inflammatory response syndrome, can predict bowel ischemia in 40% to 50% of cases (Fig. 1) [13–16]. The addition of imaging findings to clinical factors further improves the accuracy of identifying patients with bowel ischemia to 70% to 96% [17–19]. Historically, surgical services have admitted patients with adhesive SBO because the condition has been considered a surgical disease. With an increasing proportion of patients managed without surgery, however, there has been a shift in the paradigm of who primarily manages these patients while they are in the hospital. Unless patients have a clear indication for urgent surgical intervention, many patients with adhesive SBO are admitted to a primary medical service with consultation from a general surgeon. In 1 recent population-based study, 42% of patients with adhesive SBO were managed by a primary medical team [10]. In addition, the choice of primary service seems dependent on individual institutional practices because rate of admission to a primary medical service ranged from 0.2% to 95.3% across hospitals even after controlling for patient demographics and comorbidities, primary attending characteristics, and hospital factors [10].
Fig. 1. Bowel necrosis secondary to SBO. (From Zielinski MD, Bannon MP. Current management of small bowel obstruction. Adv Surg 2011;45:7; with permission.)
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DOES ADMITTING SERVICE MATTER? A REVIEW OF THE LITERATURE To date, there have been 5 retrospective cohort studies directly investigating the impact of the primary service on outcomes for SBO [10,20–23]. In this section, study findings related to the relationship between admitting service (surgical service vs medical service) and various outcomes across each of the studies are discussed (Table 1); 4 of the 5 studies had heterogeneous study cohorts consisting of patients with various etiologies for the SBO. Although adhesions were the most common cause of SBO in each of the studies, 3 of the studies also included patients with cancer, hernias, inflammatory bowel disease, volvulus, or other causes of obstruction [20,21,23], and 1 of the studies did not report the causes of SBO [22]. Time to surgery Various studies have demonstrated a relationship between delayed time to surgery and worse outcomes for adhesive SBO [11,24,25]. As a result, the relationship between primary service and number of days from admission to surgery was an endpoint in each of the 5 studies. Among 217 admissions, Malangoni and colleagues [20] demonstrated that admission to a medical service was associated with an increase in mean time to surgery of approximately 4 days compared with admission to a surgical service (6.3 vs 2.7 days; P ¼ .007). Similarly, Schwab and colleagues [21] observed a 2-day longer median time to surgery (3 days vs 1 day; P ¼ .003) across 65 patients, Oyasiji and colleagues [22] found a longer time to surgery (log-rank test; P ¼ .006) among 244 patients, Bilderback and colleagues [23] observed an approximately 2-day longer median time to surgery (51.7 hours vs 8.4 hours; P<.0001) across 130 patients, and Aquina and colleagues [10] found an 84% increase in days to surgery (incidence rate ratio [IRR] ¼ 1.84; 95% CI, 1.69, 2.01) among 23,913 admissions when comparing a primary medical service to a primary surgical service. Although time to surgery was significantly longer for patients admitted to a medical service in each of the 5 studies, this finding may be partially explained by selection bias as to which patients are admitted to a medical service compared with a surgical service. Patients admitted to a medical service were more likely to have a higher comorbidity burden [10,22,23] which would increase operative risk and favor longer nonoperative management and were less likely to have clinical signs concerning for high-grade obstruction or bowel ischemia [20], which may promote earlier surgical intervention. In addition, only 2 of the studies controlled for case mix in the analyses [10,23]. In a sensitivity analysis by Aquina and colleagues [10], however, that included 17,511 patients, a primary medical service was still independently associated with longer time to surgery (IRR ¼ 1.45; 95% CI, 1.38, 1.53) after controlling for patient age and comorbidities and excluding those who underwent operative intervention within 24 hours of admission.
Table 1 Current studies comparing outcomes for adhesive small bowel obstruction between a primary surgical service and a primary medical service Number of Author, year admissions Type of study Years
Study outcomes
Malangoni 336 et al [20], 2001
Retrospective, 1992– single 1998 institution
Schwab 65 et al [21], 2001a
Retrospective, 1997– single 2000 institution
Oyasiji 635 et al [22], 2010b
Retrospective, 2003– single 2007 institution
Bilderback 555 et al [23], 2015
Retrospective, 2008– single 2012 institution
Aquina 107,603 et al [10], 2016
Retrospective, 2002– population2013 based (New York State)
a b
Time to surgery LOS Days to tolerating a regular diet
Time to surgery LOS Bowel resection 30-d morbidity 30-d mortality
Time to surgery LOS Hospital charges Bowel resection Mortality
Time to surgery LOS 30-d morbidity Hospital charges 30-d readmission
Time to surgery LOS Hospital cost Small bowel resection 30-d readmission 30-d mortality
Study only included operative cases. No analysis for the nonoperative subgroup was performed.
Significant findings (medical service vs surgical service) Nonoperative group Shorter LOS Shorter time to tolerating a regular diet Operative group Longer time to surgery Longer LOS Operative group Longer time to surgery Longer LOS Higher morbidity rate Higher mortality rate Overall Longer LOS Lower bowel resection rate Operative group Longer time to surgery Longer LOS Higher hospital charges Nonoperative group No differences Operative group Longer time to surgery Longer LOS Higher hospital charges Nonoperative group Longer LOS Higher hospital cost Higher readmission rate Operative group Longer time to surgery Longer LOS Higher hospital cost Higher mortality rate
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Length of stay The relationship between admitting service and LOS was evaluated in each of the 5 studies. Although each of the studies compared LOS after operative intervention [10,20–23], only 3 of the studies evaluated LOS after nonoperative management [10,20,23]. In the study by Oyasiji and colleagues [22] that grouped nonoperative and operative management together into 1 analysis, the investigators observed longer LOS for medical services (7.5 vs 6.1 days; P ¼ .01) compared with surgical services. Nonoperative management The studies had conflicting findings regarding LOS after nonoperative management. Among 119 admissions for SBO, Malangoni and colleagues [20] observed a shorter LOS (4.8 vs 7.2 days; P ¼ .02) for patients admitted to a medical service. The investigators also found that patients admitted to a medical service had a shorter time to diet resumption (3.1 days vs 4.3 days; P ¼ .03) [20]. In contrast, Aquina and colleagues [10] found that patients admitted to a medical service had an approximately 40% increase in LOS (IRR ¼ 1.39; 95% CI, 1.24, 1.56) after controlling for case mix among 83,690 admissions for adhesive SBO. Bilderback and colleagues [23] found no significant difference in LOS between admitting services across 425 admissions. Operative management There were more consistent findings across studies with respect to LOS after operative management. Each of the 4 studies demonstrated longer LOS for patients admitted to medical services. Malangoni and colleagues [20] observed an approximately 5-day difference in mean overall LOS (22.8 days vs 17.9 days; P<.0001), Schwab and colleagues [21] found a 5-day difference in median LOS (13 days vs 8 days; P ¼ .02) , Oyasiji and colleagues [22] observed a 3-day difference in mean LOS (12.3 days vs 9.1 days; P ¼ .02), Bilderback and colleagues [23] demonstrated an approximately 3-day difference in median LOS (9.57 days vs 6.99 days; P ¼ .002), and Aquina and colleagues [10] observed a 36% increase in LOS (IRR ¼ 1.36; 95% CI, 1.25, 1.49) when comparing a primary medical service to a primary surgical service. Again, some of the differences in LOS may be explained by higher comorbidity burden among patients admitted to a medical service. The study by Aquina and colleagues [10], however, controlled for case mix. Hospital cost Three of the studies compared either hospital charges or costs across admitting services [10,22,23]. Oyasiji and colleagues [22] ($62,778 vs $46,258; P ¼ .05) and Bilderback and colleagues [23] ($38,800 vs $30,100; P ¼ .02) observed that medical services had higher hospital charges compared with surgical services for the operative subgroups. There was no significant difference in hospital charges between admitting services after nonoperative management in Bilderback and colleagues’ study [23]. Aquina and colleagues [10] observed significantly higher hospital costs accrued for medical services for both the
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nonoperative (IRR ¼ 1.38; 95% CI, 1.21, 1.57) and operative (IRR ¼ 1.38; 95% CI, 1.11, 1.71) subgroups. Bowel resection Three of the studies compared the rate of bowel resection across admitting services [10,21,22]. Oyasiji and colleagues [22] observed a lower rate of bowel resection for patients admitted to a medical service (5.2% vs 13.1%; P ¼ .007) across the entire study cohort. There was no significant difference, however, in the rate of bowel resection between admitting services within the operative subgroup (23%vs 30%; P ¼ .44). There was no significant difference in the rate of bowel resection between primary medical services and primary surgical services in the Schwab and colleagues [21] (45.5% vs 34.9%; P ¼ .43) and Aquina and colleagues [10] (odds ratio [OR] ¼ 1.04; 95% CI, 0.90, 1.19) studies. Time to surgery was independently associated, however, with higher odds of small bowel resection (OR ¼ 1.02; 95% CI, 1.02, 1.03) in the Aquina and colleagues [10] study as well as in previous studies, suggesting that admission to a medical service may indirectly increase the rate of small bowel resection through a delay in surgical intervention [11,24]. Thirty-day readmission Two of the studies compared the rate of 30-day readmission between admitting services [10,23]. Bilderback and colleagues [23] did not observe any significant differences in readmission rates between medical and surgical services across the nonoperative (5.1% vs 13.7%; P ¼ .11) and operative subgroups (12.3% vs 22.7%; P ¼ .09). Aquina and colleagues [10], however, did observe differences between the primary services. After nonoperative management, primary medical services were independently associated with an approximately 40% higher odds of unscheduled 30-day readmission (OR ¼ 1.39; 95% CI, 1.29, 1.50). Although not quite reaching statistical significance, medical services had a 13% higher odds of readmission (OR ¼ 1.13; 95% CI, 0.97, 1.32) compared with surgical services. Operative morbidity Two of the studies investigated 30-day morbidity rates after operative intervention [21,23]. Patients had a significantly higher rate of morbidity if admitted to a medical service (45.5% vs 11.6%, P ¼ .004) in the study by Schwab and colleagues [21]. Bilderback and colleagues [23], however, observed no difference in the complication rates between medical and surgical services (30.4% vs 27.5%; P ¼ .87) . Operative mortality Three of the studies compared mortality rates between admitting services after operative intervention with fairly consistent results [10,21,22]. Although not statistically significant, Oyasiji and colleagues [22] observed a higher mortality rate for medical services compared with surgical services (11.8% vs 3.8%; P ¼ .07). Schwab and colleagues [21] found a significantly higher 30-day mortality rate for patients admitted to a medical service (27.3% vs 2.3%; P ¼ .005),
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and Aquina and colleagues [10] observed that a primary medical service was independently associated with an approximately 2-fold higher odds of 30-day mortality compared with a primary surgical service (OR ¼ 1.92; 95% CI, 1.50, 2.47). KEYS TO IMPROVING OUTCOMES Possible explanations for differences in outcomes across admitting services The 5 studies, discussed previously, showed significant differences in outcomes between medical and surgical services. The studies demonstrated that admission to a medical service was associated with a delayed time to surgery, longer LOS, higher hospital cost, and higher operative mortality compared with admission to a primary surgical service. Therefore, these findings support policies favoring admission to a surgical service. These studies, however, did not evaluate possible reasons for this disparity in outcomes. Nonetheless, there are several possible explanations for these differences. With respect to nonoperative management, variation in the timing and duration of nasogastric tube decompression and timing, type, and number of radiologic images obtained may explain some of the differences between primary medical and surgical services. Although there are currently no standardized algorithms or protocols in the nonoperative management of adhesive SBO, Wangensteen outlined several criteria for removal of the nasogastric tube in his book, The Therapeutic Problem in Bowel Obstruction: A Physiologic and Clinical Consideration [26]. The criteria included cessation of ‘‘gas pains,’’ a decrease of abdominal distention, visualization of colonic gas on radiologic examination in the setting of complete obstruction, less fluid output from the nasogastric tube, and toleration of temporary discontinuation of nasogastric suction without pain [1,26]. These clinical markers are still the most commonly used indicators to guide nasogastric tube management, but variation may exist across providers. In addition, the use of contrast CT imaging not only has been shown to aid in diagnosing bowel ischemia but also may be therapeutic in cases of partial SBO. Water-soluble contrast results in shifts of fluid into the intestinal lumen and a resulting increase in the pressure gradient across the site of obstruction, which may hasten return of bowel function and reduce LOS [27–29]. Therefore, variation in the timing, type, and number of radiologic images across primary services may affect LOS and cost for patients who undergo nonoperative management. One possible explanation for differences in operative outcomes is a delay or failure to recognize signs of bowel ischemia with a concomitant postponement in surgical consultation for patients admitted to a medical service. Treatment delay is associated with a higher risk of bowel resection [10,11,24], higher morbidity [30,31], longer LOS [10,25,30], higher hospital cost [10], and a higher rate of postoperative mortality [10,25,31]. Less familiarity or experience in managing patients with adhesive SBO by medicine providers and subsequent failure in promptly recognizing worrisome clinical findings, such as
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leukocytosis, fever, tachycardia, and localized tenderness, may lead to a delay in surgical intervention and lead to worse outcomes [10,13]. Another possible explanation for the disparity in operative mortality is a difference in the rate of failure to rescue between admitting services. Recent studies have demonstrated that variation in postoperative mortality rates across hospitals are not due to differences in complication rates but are a result of differences in failure to rescue, or how well patients are managed and rescued from a complication [32–34]. Again, less experience in managing postoperative patients may explain differences in failure to rescue rates across admitting providers. This hypothesis is supported by studies suggesting that higher surgeon and hospital volume, which is a proxy for experience and scope of practice, is associated with lower failure to rescue rates [34–37]. Standardization of management Given the likely wide variation in management of patients with adhesive SBO across provider teams, standardizing management by following best-practice guidelines would likely reduce the disparity between admitting services and improve outcomes. The Eastern Association for the Surgery of Trauma (EAST) published updated evidence-based guidelines for the evaluation and management of SBO in 2012 (Table 2) [27]. In the diagnosis and evaluation of SBO, water-soluble contrast CT imaging is recommended to diagnose obstruction (accuracy ¼ 83%–94%), determine the level of obstruction (accuracy ¼ 93%), identify the cause of obstruction (accuracy ¼ 80%–91%), and detect bowel ischemia (sensitivity 85%–100%) or small bowel volvulus (Box 1) [27,38–45]. Furthermore, multiplanar CT reconstruction can further identify transition points and the site of obstruction (Fig. 2) [46]. In the management of SBO, patients with clinical factors or imaging results concerning for bowel ischemia should undergo early operative exploration. Those without these concerning factors can safely undergo initial nonoperative management irrespective of the grade of obstruction [7,9,12]. For those who do not have resolution, a water-soluble contrast study should be considered at 48 hours due to its diagnostic and therapeutic benefits [27–29]. Finally, patients without resolution by days 3 to 5 should either undergo a water-soluble contrast study or operative intervention [6,25]. Admission paradigms Given the findings of the studies, discussed previously, EAST recommends that patients with SBO generally be admitted to a surgical service [27]. Wide institutional variation currently exists with respect to the choice of admitting service [10]. In addition, the implementation of institutional protocols may help reduce the time to surgery and reduce LOS for patients admitted to a medical service. In a study by Wahl and colleagues [47], including 730 SBO admissions from 2010 to 2011, the investigators tracked outcomes at a single institution after implementation of an SBO triage and initial management guidelines (Box 2). After application of the paradigm, there was a decrease in the time to general surgery consultation (3.4 days vs 1.7 days; P<.001), shorter
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Table 2 Recommendations from the 2012 Eastern Association for the Surgery of Trauma practice management guideline for small bowel obstruction Recommendation Diagnosis 1. CT scan of the abdomen and pelvis should be considered in all patients with SBO. 2. Water-soluble contrast study should be considered in patients who fail to improve after 48 h of nonoperative management. 3. Multidetector CT scanner and multiplanar reconstruction should be used if available. 4. MRI and ultrasound are possible alternative imaging modalities to CT. 5. CT scan should be considered to help diagnose small bowel volvulus. Management 1. Patients with generalized peritonitis or other evidence of clinical deterioration (fever, leukocytosis, tachycardia, metabolic acidosis, and continuous pain) should undergo timely surgical exploration. 2. Patients without evidence of clinical deterioration can safely undergo initial nonoperative management. 3. CT findings consistent with bowel ischemia should suggest a low threshold for operative intervention. 4. Laparoscopic treatment of SBO is a viable alternative to laparotomy in selected cases. 5. Water-soluble contrast should be considered for patients with partial SBO that has not resolved in 48 h. 6. Patients without resolution of the SBO after 3–5 d of nonoperative management should undergo water-soluble contrast study or surgery. 7. Patients with SBO should generally be admitted to a surgical service.
Recommendation levela Level 1 Level 2 Level 3 Level 3 Level 3 Level 1
Level 1 Level 2 Level 2 Level 2 Level 3 Level 3
a
Level 1: this recommendation is convincingly justifiable based on the available scientific information alone. Level 2: this recommendation is reasonably justifiable by available scientific evidence and strongly supported by expert critical care opinion. Level 3: this recommendation is supported by available data, but adequate scientific evidence is lacking. Adapted from Maung AA, Johnson DC, Piper GL, et al. Evaluation and management of small-bowel obstruction: An Eastern Association for the Surgery of Trauma practice management guideline. J Trauma Acute Care Surg 2012; 73(5):S363; with permission.
time from admission to surgery (0.9 days vs 0.4 days; P<.05), and a decrease in LOS (8 days vs 6 days; P<.001) for patients admitted to a medical service. These findings suggest that the utilization of admission guidelines and standardization of care can improve outcomes for primary medical services. Despite improvements in these outcomes for medical services, however, surgical services still had shorter time to operative intervention and LOS compared with medical services in the study. Medical comanagement Although evidence from previous studies suggests that patients may have better outcomes if primarily managed by a surgical service, these findings do not preclude the comanagement of complex patients with multiple comorbidities by
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Box 1: List of CT findings for bowel ischemia 1. Bowel wall thickening (>3 mm) 2. Mesenteric edema 3. Fluid in mesentery and/or peritoneal cavity 4. Abnormal bowel wall enhancement, either increased or decreased 5. Occlusion of mesenteric vessels 6. Engorged mesenteric veins 7. Whirl sign 8. Closed loop obstruction or volvulus 9. Pneumatosis 10. Mesenteric venous gas 11. Portal venous gas From Paulson EK, Thompson WM. Review of small-bowel obstruction: The diagnosis and when to worry. Radiology 2015; 275(2):340; with permission.
Fig. 2. Coronal image from contrast-enhanced CT scan demonstrating a small bowel feces sign (small arrows) proximal to the transition point (large arrow) of an adhesive SBO. (From Paulson EK, Thompson WM. Review of small-bowel obstruction: The diagnosis and when to worry. Radiology 2015; 275(2):337; with permission.)
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Box 2: Example of a published institutional triage and management guideline for small bowel obstruction Evaluation 1. Patients with symptoms consistent with possible SBO should have the following: a. Complete physical examination, including a digital rectal examination and gynecologic examination if appropriate b. Acute abdominal series c. Complete blood cell count, comprehensive panel, lactate, and urinalysis 2. CT scan is not required for all patients, but if the history, physical examination, and initial imaging are supportive of a possible bowel obstruction and there is no absolute indication for an emergent surgical consultation (free air, peritonitis, nonreducible symptomatic hernia, or abdominal surgery in the last 30 days), then an abdominal CT with intravenous and oral contrast should be performed unless there is a contraindication to the study. The study can be done without intravenous contrast for those with contrast allergy or high creatinine. Relative contraindications to CT imaging may include multiple recent studies or recent surgery and reimaging should then be left to the discretion of the care providers. Initial treatment 3. Initial therapy for all patients diagnosed with complete or high-grade partial bowel obstructions should be a. Placement of an 18F nasogastric tube on continuous suction b. Intravenous fluid with nothing-by-mouth status c. Careful monitoring of urine output d. Serial abdominal examinations e. Early general surgery consultation to determine need for operative management 4. Initial therapy for partial SBO patients should include a. Placement of a nasogastric tube on continuous suction if ongoing vomiting b. Intravenous fluid with nothing-by-mouth status c. Careful monitoring of urine output d. Serial abdominal examinations e. General surgery consultation if no improvement in 48 hours or with change or worsening of the patient’s condition or abdominal examination Admission 5. If a transition point is identified on CT or a patient is deemed an emergent operative candidate or a patient has had an abdominal surgery within the past 30 days, the patient is admitted to a surgical service. Exceptions that may warrant a medical service admission could be a. Patients with intra-abdominal metastases b. Patients with active inflammatory bowel disease who are to have a trial of systemic therapy
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c. Acute, severe medical conditions requiring stabilization (ie, acute myocardial infarction, and severe exacerbation of chronic obstructive pulmonary disease) 6. Patients with known dilated bowel secondary to dysmotility problems or other medical conditions can be admitted to medicine. Examples of this include a. Chronic narcotic-induced obstipation b. Dysmotility or constipation from chronic psychotropic use or mental/developmental disorders c. Cystic fibrosis patients d. Collagen vascular diseases with bowel involvement From Wahl WL, Wong SL, Sonnenday CJ, et al. Implementation of a small bowel obstruction guideline improves hospital efficiency. Surgery 2012;152(4):627; with permission.
hospitalists. Although there are currently no studies including the population of patients with adhesive SBO, evidence from the orthopedic surgery literature suggests that involvement of hospitalists improves outcomes. In a study by Phy and colleagues [48], the investigators observed that the use of a hospitalist comanagement model decreased time to surgery and shortened LOS for older patients with a hip fracture. Furthermore, a randomized controlled trial demonstrated that a hospitalist-orthopedic team model reduced minor complications and resulted in higher satisfaction among nurses and surgeons after elective hip and knee arthroplasty [49]. The introduction of similar hospitalist comanagement models may improve outcomes for adhesive SBO patients with high comorbidity burden. SUMMARY Through the work of Wangensteen and recent advancements in radiologic imaging, there has been an increasing trend toward nonoperative management. As a result, wide institutional variation currently exists with respect to the admitting service for patients with adhesive SBO. Current studies, however, support primary management of SBO by surgeons because admission to medical services is associated with a delayed time to operative intervention, longer LOS, higher cost, and a higher operative mortality rate. Future studies should focus on variation in the management of adhesive SBO across providers, the effect of standardized management protocols in limiting this variation, and the impact of hospitalist comanagement models on outcomes for patients with a higher comorbidity burden. References [1] Faryniuk A, MacDonald A, van Boxel P. Amnesia in modern surgery: revisiting Wangensteen’s landmark studies of small bowel obstruction. Can J Surg 2015;58(2):83–4. [2] Mucha P Jr. Small intestinal obstruction. Surg Clin North Am 1987;67(3):597–620. [3] Simorov A, Shaligram A, Shostrom V, et al. Laparoscopic colon resection trends in utilization and rate of conversion to open procedure: a national database review of academic medical centers. Ann Surg 2012;256(3):462–8.
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