Abstract
Background
Small bowel volvulus is a rare entity in Western adults. Greater insight into epidemiology and outcomes may be gained from a national database inquiry.
Methods
The Nationwide Inpatient Sample (1998–2010), a 20% stratified sample of United States hospitals, was retrospectively reviewed for small bowel volvulus cases (ICD-9 560.2 excluding gastric/colonic procedures) in patients ≥18-years old.
Results
There were 2,065,599 hospitalizations for bowel obstruction (ICD-9 560.x). Of those, there were 20,680 (1.00%) small bowel volvulus cases; 169 were attributable to intestinal malrotation. Most cases presented emergently (89.24%) and operative management was employed more frequently than non-operative (65.21% vs. 34.79%, P<0.0001). Predictors of mortality included age >50-years, Charlson comorbidity index ≥1, emergent admission, peritonitis, acute vascular insufficiency, coagulopathy, and non-operative management (P<0.0001).
Conclusions
As the first population-based epidemiological study of small bowel volvulus, our findings provide a robust representation of this rare cause of small bowel obstruction in American adults.
Keywords: Intestinal malrotation, Small Bowel Volvulus, Acute abdomen, National Inpatient Sample, Charlson comorbidity
Introduction
Small bowel volvulus (SBV) is defined as the twisting of the small bowel around its mesenteric axis. This can lead to bowel obstruction, ischemia, infarction or perforation. Typically, SBV is thought to be a diagnosis in newborns, because one-in-500 live births have intestinal malrotation (IM) and approximately 80% of these IM patients will present with SBV within the first month of life.[1-3] As a result, SBV secondary to IM is most common in children and young adults. However, in rare circumstances, adults can present with SBV secondary to IM.[4, 5] What is less appreciated is that adults can also present with small bowel volvulus (SBV) secondary to adhesions, tumors or Meckel’s diverticula.[6] Studies dating back several decades suggest that the annual incidence of SBV is 1.7-5.7 per 100,000 adults in Western countries, and 24-60 per 100,000 adults in Africa, the Middle East and Asia.[7-9] The higher rate in the latter regions has been associated with fiber-rich and serotonin-rich diets, as well as fasting.[8] But, because of its rarity, relatively little is known about the epidemiology, presentation and management of SBV in Western adults; our understanding is solely based upon case reports and single institution case series that are no larger than 129 patients in size.[1, 10, 11] The purpose of this study was to describe the epidemiology and outcomes of both SBV and SBV with IM in U.S. adults. Therefore, we hypothesized that a national database inquiry would provide greater insight into these questions through a population-based analysis.
Methods
Retrospective analysis of the United States Nationwide Inpatient Sample (NIS) was performed spanning the years 1998 through 2010. The NIS, operated by the Agency for Healthcare Research and Quality (AHRQ), is a 20% stratified sample of inpatient discharges from over 1,050 hospitals in 45 states.[12] It covers 95% of the U.S. population and is the largest all-payer inpatient database. National trends can be identified due to weighted sampling. The NIS includes more than 100 clinical and non-clinical data variables from each hospital stay, including primary and secondary diagnoses and procedures, admission and discharge types, patient demographics (i.e., age, sex, Charlson comorbidity index, etc.), insurance type, total charges, length of stay, and hospital characteristics.
We determined the total number of adult patients (i.e., 18 years of age and older) with any bowel obstruction in the database as defined by ICD-9 diagnosis codes 560.0-1, 560.30-31, 560.39, 560.81, 560.89, 560.9 or 560.2.
To construct the SBV study cohort, we identified hospital stays with the primary or secondary ICD-9 diagnosis code of 560.2, which represents any volvulus in patients 18 years of age and older. This was analogous to Halabi and colleague’s coding for colonic volvuli.[13] However, since this diagnosis code is not specific for the volvulus location, we then excluded all patients undergoing gastric or colonic procedures during the same hospitalization in order to identify patients undergoing small bowel procedures during the same hospitalization. By excluding gastric and colonic procedures associated with gastric volvuli and colonic volvuli,[13] we aimed to identify the study cohort with SBV (Supplemental Table 1). Although this approach may underestimate the true SBV population, which may have undergone gastric or colonic procedures, we preferred this potential type II error as opposed to overestimation with a type I error.
Patients with SBV and IM were also identified within the SBV cohort using the ICD-9 code 751.4, which describes anomalies of intestinal fixation including congenital adhesions, Jackson’s membrane, malrotation of colon, rotation of cecum/colon or universal mesentery. SBV and IM patients had both 560.2 and 751.4 diagnosis codes. Emergent versus non-emergent admissions were identified based on the NIS definition of emergency or urgent admission. Findings upon presentation, including acute vascular insufficiency, peritonitis, coagulopathy, and pneuomoperitoneum were defined using ICD-9 codes 557.0-1,9, 567.1-9, 286.0-9, and 568.89, respectively. Management of SBV was defined as operative based upon procedure codes listed in Supplemental Table 2. Non-operative management included procedures such as nasogastric decompression, mechanical ventilation and supportive care.
Patient demographics, Charlson comorbidity index, hospital types (i.e., teaching versus non-teaching), hospital location (i.e., rural versus urban), findings upon presentation, operative procedures and in-hospital mortality were described for the entire SBV cohort. The Charlson comorbidity index is a measure of comorbidities based on the presence or absence of certain diagnoses in the patient. These are then combined together in a weighted formula.[14] Hospital teaching status was defined by the presence of a general surgical residency program. Univariate tests, utilizing chi-square and Student’s t-test were performed for comparison of categorical and continuous variables, respectively. Multivariate analysis was performed to assess for differences in in-hospital mortality, controlling for age, sex, race, Charlson comorbidity index, year, emergent admission, presentation (i.e., peritonitis, acute vascular insufficiency, pneumoperitoneum, and coagulopathy), teaching hospital status, hospital location, and utilization of operative management. Statistical analyses were performed using STATA 11.1 software (StataCorp, College Station, TX, USA), with statistical significance set at a P-value ≤ 0.05.
Results
Hospitalizations for Small Bowel Volvulus
There were 2,065,599 hospitalizations for bowel obstruction (ICD-9 560.x) observed over this 13-year period from 1998 to 2010, representing an estimated 10.33 million hospitalizations across the entire United States. After excluding gastric and colonic procedures, 20,680 hospitalizations (1.00%) were attributable to SBV. Among patients hospitalized for bowel obstruction, the overall mortality was 5.61% and the mortality rates in the operative and non-operative groups were similar (5.58% vs. 5.62% P=0.33).
Demographics of Small Bowel Volvulus Cohort
Over the study period, 20,680 patients with SBV were recorded in the NIS, projecting to approximately 103,400 patients nationwide (Table 1). These patients were predominately female (56.60%) and white (75.34%) with a mean age of 66.0 ± 19.4 years (range: 18-103 years). These demographics were generally similar to the entire cohort of patients presenting with bowel obstruction, despite statistically significant differences observed due to the large sample sizes (Table 1). Most cases presented emergently (89.24%) with 19.1% of patients presenting with signs of an acute abdomen, such as peritonitis, acute vascular insufficiency or pneumoperitoneum. Overall, adhesive disease appeared to be the leading cause of SBV (32.44%). Operative management was employed in 65.21% of admissions and the average time from admission to operation was 1.6 ± 2.9 days. The overall inpatient mortality rate was 7.92% in all patients with SBV. In subset analyses, the mortality rate was 4.78% among patients that had an operation on the day of admission, while it was 6.65% among patients that had an operation after the day of admission (P<0.0001). The mean time from admission to death was 8.11 ± 11.6 days (range: 0-209 days).
Table 1.
Characteristics of patients with bowel obstruction and small bowel volvulus.*
| Demographics | Bowel Obstruction (%) | Volvulus (%) | P-value |
|---|---|---|---|
| Total Patients | 2,063,457 | 20,680 | |
| Age, mean (sd), years | 64.6 (17.8) | 66.0 (19.4) | <0.0001 |
| Sex | 0.039 | ||
| Female | 1,153,682 (55.89%) | 11,696 (56.60%) | |
| Male | 910,682 (44.11%) | 8,970 (43.30%) | |
| Race | <0.0001 | ||
| White | 1,212,965 (76.35%) | 12,167 (75.34%) | |
| Black | 195,071 (12.28%) | 2,218 (13.73%) | |
| Hispanic | 110,579 (6.96%) | 1,058 (6.55%) | |
| Asian or Pacific Islander | 30,988 (1.95%) | 299 (1.85%) | |
| Indian/Other | 38,999 (2.46%) | 408 (2.53%) | |
| Insurance | <0.0001 | ||
| Medicare | 1,168,594 (56.70%) | 12,255 (59.38%) | |
| Medicaid | 147,270 (7.15%) | 1,238 (6.00%) | |
| Private | 624,037 (30.28%) | 5,863 (28.41%) | |
| Self-pay | 644,330 (3.12%) | 762 (3.69%) | |
| No charge | 6,515 (0.32%) | 65 (0.31%) | |
| Other | 50,376 (2.44%) | 456 (2.21%) | |
| Charlson Comorbidity Index | <0.0001 | ||
| 0 | 846,468 (40.98%) | 10,601 (51.26%) | |
| 1-2 | 661,957 (32.05%) | 6,800 (32.88%) | |
| ≥3 | 557,174 (26.97%) | 3,279 (15.86%) | |
| Presentation | <0.0001 | ||
| Emergent | 1,436,630 (78.15%) | 16,322 (89.24%) | |
| Elective | 401,560 (21.85%) | 1,968 (10.76%) | |
| Hospital Type | |||
| Urban | 1,740,835 (84.28%) | 17,061 (82.50%) | <0.0001 |
| Teaching | 833,369 (40.48%) | 8,267 (40.12%) | 0.295 |
| Rural | 324,764 (15.72%) | 3,619 (17.50%) | <0.0001 |
| Management | |||
| Non-operative | 1,683,036 (81.48%) | 7,194 (34.79%) | <0.0001 |
| Operative | 382,563 (18.42%) | 13,486 (65.21%) | <0.0001 |
| Adhesiolysis | 261,446 (12.66%) | 6,709 (32.44%) | <0.0001 |
| Small bowel resection | 101,397 (4.91%) | 4,954 (23.96%) | <0.0001 |
| Manipulation | 6,542 (0.32%) | 2,763 (12.26%) | <0.0001 |
| Dilation | 19,849 (0.96%) | 2,451 (11.85%) | <0.0001 |
| Small bowel surgery | 75,182 (3.64%) | 2,021 (9.77%) | <0.0001 |
| Destruction of peritoneal tissue | 34,578 (1.67%) | 888 (4.29%) | <0.0001 |
| Laparoscopic | 36,777 (1.78%) | 855 (4.13%) | <0.0001 |
| Exploratory laparotomy | 22,070 (1.07%) | 544 (2.63%) | <0.0001 |
| Ladds | 1,709 (0.08%) | 72 (0.35%) | <0.0001 |
| Small bowel pexy | 579 (0.03%) | 68 (0.33%) | <0.0001 |
| Presentations of acute abdomen | |||
| Acute vascular insufficiency | 50,801 (2.46%) | 3,510 (16.97%) | <0.0001 |
| Peritonitis | 39,599 (1.92%) | 639 (3.09%) | <0.0001 |
| Coagulopathy | 24,913 (1.21%) | 265 (1.28%) | 0.318 |
| Malrotation | 1,745 (0.08%) | 169 (0.82%) | <0.0001 |
| Pneumoperitoneum | 4,911 (0.24%) | 85 (0.41%) | <0.0001 |
| Mortality | |||
| In-hospital mortality | 115,730 (5.61%) | 1,637 (7.92%) | <0.0001 |
| Admission to death time, mean (sd), days | 14.1 (17.5) | 8.11 (11.6) | <0.0001 |
Percentages are based upon the denominator of available data.
Demographics of Small Bowel Volvulus Cohort with Intestinal Malrotation
Among the hospitalizations for SBV, 0.82% (169 unweighted cases) was attributable to SBV+IM. The average age of presentation was 48.2 ± 21.2 years (range: 18-95 years) with 53.85% female (Table 2). SBV+IM was most common in white patients (77.54%) and most hospitalizations were on an emergent basis (89.73%). Operative management was utilized in 79.29% of hospitalizations and the average time from admission to operation was 1.0 ± 1.9 days. The inpatient mortality was 2.37%.
Table 2.
Characteristics of patients with small bowel volvulus and intestinal malrotation.*
| Demographics | Number (%) |
|---|---|
| Total Patients | 169 |
| Age, mean (sd), years | 48.2 (21.2) |
| Sex | |
| Female | 91 (53.85%) |
| Male | 78 (46.15%) |
| Race | |
| White | 107 (77.54%) |
| Black | 16 (11.59%) |
| Hispanic | 10 (7.25%) |
| Asian or Pacific Islander | 3 (2.17%) |
| Indian/Other | 2 (1.45%) |
| Insurance | |
| Medicare | 45 (26.63%) |
| Medicaid | 20 (11.83%) |
| Private | 83 (49.11%) |
| Self-pay | 14 (8.28%) |
| No charge | 1 (0.59%) |
| Other | 6 (3.55%) |
| Charlson Comorbidity Index | |
| 0 | 120 (71.01%) |
| 1-2 | 29 (17.16%) |
| ≥3 | 20 (11.83%) |
| Presentation | |
| Emergent | 131 (89.73%) |
| Elective | 15 (10.27%) |
| Hospital Type | |
| Urban | 152 (89.94%) |
| Teaching | 80 (47.34%) |
| Rural | 17 (10.06%) |
| Management | |
| Non-operative | 35 (20.71%) |
| Operative | 134 (79.29%) |
| Adhesiolysis | 88 (52.07%) |
| Manipulation | 50 (29.59%) |
| Ladds | 32 (18.93%) |
| Small bowel resection | 26 (15.38%) |
| Small bowel surgery | 18 (10.65%) |
| Laparoscopic | 13 (7.69%) |
| Destruction of peritoneal tissue | 3 (1.78%) |
| Exploratory laparotomy | 3 (1.78%) |
| Dilation | 1 (0.59%) |
| Small bowel pexy | 1 (0.59%) |
| Presentations of acute abdomen | |
| Acute vascular insufficiency | 22 (13.02%) |
| Peritonitis | 5 (2.96%) |
| Mortality | |
| In-hospital mortality | 4 (2.37%) |
| Admission to death time, mean (sd), days | 1 (0.82) days |
Percentages are based upon the denominator of available data.
Characteristics of Small Bowel Volvulus Patients with Emergent or Elective Presentations
We performed unadjusted analyses of patients presenting emergently or electively (Table 3). Patients presenting emergently were older (66.2 vs. 64.0, P<0.0001) and more likely to receive operative management (66.39% vs. 58.38%, P<0.0001). The overall mortality was higher in the emergent group (8.02% vs. 5.44%, P<0.0001).
Table 3.
Characteristics of patients with small bowel volvulus presenting emergently or electively.*
| Emergent | Elective | P-value | |
|---|---|---|---|
| Total Patients | 16,322 (78.90%) | 1,968 (9.50%) | |
| Age, mean (sd), years | 66.2 (19.5) | 64.0 (18.5) | <0.0001 |
| Sex | 0.178 | ||
| Female | 9,233 (56.57%) | 1,144 (58.16%) | |
| Male | 7,089 (43.43%) | 823 (41.84%) | |
| Race | <0.0001 | ||
| White | 9,482 (76.30%) | 1,135 (80.96%) | |
| Black | 1,890 (15.21%) | 143 (10.20%) | |
| Hispanic | 625 (5.03%) | 60 (4.28%) | |
| Asian or Pacific Islander | 125 (1.01%) | 21 (1.50%) | |
| Indian/Other | 305 (2.45%) | 43 (3.06%) | |
| Insurance | <0.0001 | ||
| Medicare | 9,803 (60.18%) | 1,079 (55.05%) | |
| Medicaid | 920 (5.65%) | 111 (5.66%) | |
| Private | 4,528 (27.80%) | 672 (34.29%) | |
| Self-pay | 636 (3.90%) | 49 (2.50%) | |
| No charge | 61 (0.37%) | 4 (0.20%) | |
| Other | 341 (2.09%) | 45 (2.30%) | |
| Charlson Comorbidity Index | 0.542 | ||
| 0 | 8,380 (51.34%) | 1,021 (51.88%) | |
| 1-2 | 5,420 (33.21%) | 617 (31.35%) | |
| ≥3 | 2,522 (15.45%) | 330 (16.77%) | |
| Hospital Type | |||
| Teaching | 6,751 (41.53%) | 740 (37.74%) | 0.001 |
| Rural | 2,937 (18.07%) | 460 (23.37%) | <0.0001 |
| Urban | 13,319 (81.93%) | 1,508 (76.63%) | <0.0001 |
| Management | |||
| Non-operative | 5,486 (33.61%) | 819 (12.99%) | <0.0001 |
| Operative | 10,836 (66.39%) | 1,149 (58.38%) | <0.0001 |
| Adhesiolysis | 5,338 (32.70%) | 632 (32.11%) | 0.598 |
| Small bowel resection | 4,048 (24.80%) | 344 (17.48%) | <0.0001 |
| Manipulation | 2,256 (13.82%) | 246 (12.50%) | 0.107 |
| Dilation | 2,046 (12.54%) | 140 (7.11%) | <0.0001 |
| Small bowel surgery | 1,607 (9.85%) | 193 (9.81%) | 0.957 |
| Destruction of peritoneal tissue | 638 (3.91%) | 137 (6.96%) | <0.0001 |
| Laparoscopic | 646 (3.96%) | 115 (5.84%) | <0.0001 |
| Exploratory laparotomy | 444 (2.72%) | 46 (2.34%) | 0.320 |
| Ladds | 56 (0.34%) | 11 (0.56%) | 0.134 |
| Small bowel pexy | 46 (0.28%) | 14 (0.71%) | 0.002 |
| Presentations of acute abdomen | |||
| Acute vascular insufficiency | 2,856 (17.50%) | 219 (11.13%) | <0.0001 |
| Peritonitis | 479 (2.93%) | 74 (3.76%) | 0.043 |
| Coagulopathy | 200 (1.23%) | 24 (1.22%) | 0.982 |
| Malrotation | 131 (0.80%) | 15 (0.76%) | 0.849 |
| Pneumoperitoneum | 61 (0.37%) | 15 (0.76%) | 0.011 |
| Mortality | |||
| In-hospital mortality | 1,308 (8.02%) | 107 (5.44%) | <0.0001 |
| Admission to death time, mean (sd), days | 7.8 (11.4) | 10.2 (13.7) | 0.0436 |
Percentages are based upon the denominator of available data.
Characteristics of Small Bowel Volvulus Patients Undergoing Operative or Non-operative Management
We performed unadjusted analyses of patients undergoing operative or non-operative management (Table 4). Patients undergoing operative management were significantly younger (63.8 vs. 70.1, P<0.0001) and more likely to present emergently (90.41% vs. 87.01%, P<0.0001) (Table 4). The most common procedure performed was adhesiolysis (32.44%) with 6.34% of all procedures being performed laparascopically. Additionally, 23.96% of patients underwent a bowel resection. In this subset of patients (N=4,949), the mortality rate was 7.88%. In contrast, the mortality rate was 4.81% in the patients not undergoing resection (N=8,529, P<0.0001). However, the overall mortality was higher in the non-operative cohort than the operative cohort (11.65% vs. 5.94%, P<0.0001).
Table 4.
Characteristics of patients with small bowel volvulus undergoing operative or nonoperative management.*
| Operative management | Non-operative management | P-value | |
|---|---|---|---|
| Total Patients | 13,486 (65.21%) | 7,194 (34.79%) | |
| Age, mean (sd), years | 63.8 (19.4) | 70.1 (18.6) | <0.0001 |
| Sex | 0.704 | ||
| Female | 7,638 (56.69%) | 4,058 (56.42%) | |
| Male | 5,835 (43.31%) | 3,135 (43.58%) | |
| Race | 0.001 | ||
| White | 7,925 (76.01%) | 4,242 (74.11%) | |
| Black | 1,370 (13.14%) | 848 (14.81%) | |
| Hispanic | 678 (6.50%) | 380 (6.64%) | |
| Asian or Pacific Islander | 211 (2.02%) | 88 (1.54%) | |
| Indian/Other | 242 (2.32%) | 166 (2.9%) | |
| Insurance | <0.0001 | ||
| Medicare | 7,374 (54.81%) | 4,881 (67.93%) | |
| Medicaid | 779 (5.79%) | 459 (6.39%) | |
| Private | 4,367 (32.46%) | 1,496 (20.82%) | |
| Self-pay | 569 (4.23%) | 193 (2.69%) | |
| No charge | 49 (0.36%) | 16 (0.22%) | |
| Other | 316 (2.35%) | 140 (1.95%) | |
| Charlson Comorbidity Index | <0.0001 | ||
| 0 | 7,502 (55.63%) | 3,099 (43.08%) | |
| 1-2 | 4,147 (30.75%) | 2,653 (36.88%) | |
| ≥3 | 1,837 (13.62%) | 1,442 (20.04%) | |
| Presentation | <0.0001 | ||
| Elective | 1,149 (58.38%) | 819 (41.62%) | |
| Emergent | 10,836 (90.41%) | 5,486 (87.01%) | |
| Hospital Type | |||
| Teaching | 5,509 (40.09%) | 2,758 (38.48%) | <0.0001 |
| Rural | 2,223 (16.48%) | 1,396 (19.41%) | <0.0001 |
| Urban | 11,263 (83.52%) | 5,798 (80.59%) | <0.0001 |
| Management | |||
| Laparoscopic | 855 (6.34%) | ||
| Adhesiolysis | 6,709 (32.44%) | ||
| Small bowel resection | 4,954 (23.96%) | ||
| Manipulation | 2,763 (12.26%) | ||
| Dilation | 2,451 (11.85%) | ||
| Small bowel surgery | 2,021 (9.77%) | ||
| Destruction of peritoneal tissue | 888 (4.29%) | ||
| Exploratory laparotomy | 544 (2.63%) | ||
| Ladds | 72 (0.53%) | ||
| Small bowel pexy | 68 (0.33%) | ||
| Presentations of acute abdomen | |||
| Acute vascular insufficiency | 3,210 (23.80%) | 300 (4.17%) | <0.0001 |
| Peritonitis | 543 (4.03%) | 96 (1.33%) | <0.0001 |
| Coagulopathy | 177 (1.31%) | 88 (1.22%) | 0.587 |
| Malrotation | 134 (0.99%) | 35 (0.49%) | <0.0001 |
| Pneumoperitoneum | 74 (0.55%) | 11 (0.15%) | <0.0001 |
| Mortality | |||
| In-hospital mortality | 800 (5.94%) | 837 (11.65%) | <0.0001 |
| Admission to death time, mean (sd), days | 10.2 (12.8) | 6.1 (10.0) | <0.0001 |
Percentages are based upon the denominator of available data.
Characteristics of Small Bowel Volvulus Patients with Intestinal Malrotation Undergoing Operative or Non-operative Management
We performed unadjusted analyses of patients undergoing operative or non-operative management in the subset of SBV+IM patients (Table 5). Patients undergoing operative management were significantly younger (46.1 vs. 56.0, P<0.05). The most common procedures performed were adhesiolysis (65.67%), bowel manipulation (37.31%), and Ladds procedure (23.88%). There was one death in the non-operative cohort (N=35) and three deaths in the operative cohort (N=134; P=NS).
Table 5.
Characteristics of patients with small bowel volvulus and intestinal malrotation undergoing operative or non-operative management.*
| Operative management | Non-operative management | P-value | |
|---|---|---|---|
| Total Patients | 134 (79.29%) | 35 (20.71%) | |
| Age, mean (sd), years | 46.1 (19.9) | 56.0 (24.3) | 0.0136 |
| Sex | 0.114 | ||
| Female | 68 (50.75%) | 12 (34.29%) | |
| Male | 66 (49.25%) | 23 (65.71%) | |
| Race | 0.651 | ||
| White | 82 (75.23%) | 25 (86.21%) | |
| Black | 13 (11.93%) | 3 (10.34%) | |
| Hispanic | 9 (8.26%) | 1 (3.45%) | |
| Asian or Pacific Islander | 3 (2.75%) | 0 | |
| Indian/Other | 2 (1.83%) | 0 | |
| Insurance | 0.359 | ||
| Medicare | 31 (23.13%) | 14 (40.00%) | |
| Medicaid | 15 (11.19%) | 5 (14.29%) | |
| Private insurance | 71 (52.99%) | 12 (34.29%) | |
| Self-pay | 11 (8.21%) | 3 (8.57%) | |
| No charge | 1 (0.75%) | 0 | |
| Other | 5 (3.73%) | 1 (2.86%) | |
| Charlson Comorbidity Index | 0.479 | ||
| 0 | 98 (73.13%) | 22 (62.86%) | |
| 1-2 | 21 (15.67%) | 8 (22.86%) | |
| ≥3 | 15 (11.19%) | 5 (14.29%) | |
| Presentation | 0.587 | ||
| Emergent | 104 (90.43%) | 27 (87.10%) | |
| Elective | 11 (9.57%) | 4 (12.90%) | |
| Hospital Type | |||
| Teaching | 66 (49.25%) | 14 (40.00%) | 0.329 |
| Rural | 11 (8.21%) | 6 (17.14%) | 0.118 |
| Urban | 123 (91.79%) | 29 (82.86%) | 0.118 |
| Management | |||
| Adhesiolysis | 88 (65.67%) | ||
| Manipulation | 50 (37.31%) | ||
| Ladds | 32 (23.88%) | ||
| Small bowel resection | 26 (19.40%) | ||
| Small bowel surgery | 18 (13.43%) | ||
| Laparoscopic | 13 (9.70%) | ||
| Destruction of peritoneal tissue | 3 (2.24%) | ||
| Exploratory laparotomy | 3 (2.24%) | ||
| Dilation | 1 (0.75%) | ||
| Small bowel pexy | 1 (0.75%) | ||
| Presentations of acute abdomen | |||
| Acute vascular insufficiency | 21 (15.67%) | 1 (2.86%) | 0.045 |
| Peritonitis | 5 (3.73%) | 0 | 0.246 |
| Mortality | |||
| Inpatient deaths | 3 (2.24%) | 1 (2.86%) | 0.830 |
| Admission to death time, mean (sd), days | 0.67 (0.58) | 2 |
Percentages are based upon the denominator of available data.
Multivariate Analysis of the Small Bowell Volvulus Cohort for Predictors of Mortality
We then performed multivariate analysis of the entire SBV cohort for predictors of mortality (Table 6). Analysis demonstrated that independent risk factors for mortality included male sex, age greater than 50 years, Charlson comorbidity index ≥1, emergent admission, peritonitis, acute vascular insufficiency, coagulopathy and non-operative management (P<0.0001). Race, hospital teaching status, hospital location, year of admission, and pneumoperitoneum had no significant impact on mortality.
Table 6.
Multivariate analysis of all patients with small bowel volvulus.
| Odds Ratio | 95% CI | P-value | ||
|---|---|---|---|---|
| Lower | Higher | |||
| Sex | ||||
| Female | (Reference) | |||
| Male | 1.17 | 1.02 | 1.36 | 0.029 |
| Race | ||||
| White | (Reference) | |||
| Black | 1.14 | 0.93 | 1.39 | 0.197 |
| Hispanic | 1.12 | 0.79 | 1.57 | 0.526 |
| Asian or Pacific Islander | 0.87 | 0.39 | 1.91 | 0.722 |
| Indian | 0.90 | 0.34 | 2.40 | 0.837 |
| Other | 1.09 | 0.71 | 1.68 | 0.694 |
| Age | ||||
| 18 – <40 | (Reference) | |||
| 40 – <45 | 1.61 | 0.70 | 3.68 | 0.263 |
| 45 – <50 | 1.50 | 0.69 | 3.27 | 0.310 |
| 50 – <55 | 2.58 | 1.36 | 4.87 | 0.004 |
| 55 – <60 | 3.38 | 1.83 | 6.23 | <0.001 |
| 60 – <65 | 4.75 | 2.60 | 8.68 | <0.001 |
| 65 – <70 | 5.79 | 3.36 | 9.99 | <0.001 |
| 70 – <75 | 5.60 | 3.26 | 9.64 | <0.001 |
| 75 – <80 | 7.94 | 4.75 | 13.26 | <0.001 |
| 80 – <85 | 12.75 | 7.76 | 20.97 | <0.001 |
| 85 – <90 | 14.62 | 8.81 | 24.26 | <0.001 |
| ≥90 | 18.23 | 10.86 | 30.59 | <0.001 |
| Charlson Comorbidity Index | ||||
| 0 | (Reference) | |||
| 1-2 | 1.59 | 1.36 | 1.87 | <0.001 |
| ≥3 | 2.34 | 1.95 | 2.81 | <0.001 |
| Presentation | ||||
| Elective Admission | (Reference) | |||
| Emergent Admission | 1.38 | 1.08 | 1.76 | 0.009 |
| Hospital Type | ||||
| Non-teaching | (Reference) | |||
| Teaching | 1.09 | 0.94 | 1.26 | 0.254 |
| Rural | (Reference) | |||
| Urban | 0.96 | 0.79 | 1.17 | 0.698 |
| Management | ||||
| Non-operative | (Reference) | |||
| Operative | 0.46 | 0.39 | 0.53 | <0.001 |
| Year | ||||
| 1998 | (Reference) | |||
| 1999 | 1.35 | 0.96 | 1.90 | 0.081 |
| 2000 | 0.96 | 0.67 | 1.38 | 0.841 |
| 2001 | 1.12 | 0.78 | 1.61 | 0.532 |
| 2002 | 0.87 | 0.59 | 1.29 | 0.495 |
| 2003 | 0.98 | 0.68 | 1.40 | 0.902 |
| 2004 | 1.08 | 0.77 | 1.52 | 0.646 |
| 2005 | 1.04 | 0.73 | 1.47 | 0.841 |
| 2006 | 0.88 | 0.62 | 1.25 | 0.48 |
| 2007 | 0.88 | 0.61 | 1.25 | 0.470 |
| 2008 | 0.88 | 0.63 | 1.22 | 0.440 |
| 2009 | 0.87 | 0.62 | 1.22 | 0.426 |
| 2010 | 0.92 | 0.65 | 1.31 | 0.654 |
| Presentations of acute abdomen | ||||
| Peritonitis | ||||
| No | (Reference) | |||
| Yes | 2.41 | 1.74 | 3.33 | <0.001 |
| Acute vascular insufficiency | ||||
| No | (Reference) | |||
| Yes | 3.09 | 2.60 | 3.67 | <0.001 |
| Coagulopathy | ||||
| No | (Reference) | |||
| Yes | 6.31 | 4.29 | 9.28 | <0.001 |
| Pneumoperitoneum | ||||
| No | (Reference) | |||
| Yes | 2.32 | 0.76 | 7.06 | 0.139 |
Discussion
In this study, we report the first population-based analysis of a cohort of 20,680 adults with small bowel volvuli (SBV) in the United States. Of an estimated 10.33 million hospitalizations for bowel obstructions over the 13-year study period, 1.00% was attributable to SBV. Of this fraction, 0.82% (i.e., 0.0082% of all bowel obstructions) were patients presenting with small bowel volvulus (SBV) and intestinal malrotation (IM). SBV with and without IM is a rare cause of bowel obstruction in the U.S. We define the epidemiology, presentation and management of SBV in Western adults. We found that SBV patients tended to be older, white females while SBV+IM patients tended to be younger. Most patients presented emergently, a factor associated with higher in-hospital mortality. Operative management was more commonly utilized and non-operative management was significantly associated with higher mortality rates, although patient age and comorbidities likely confound any causal relationship between management choice and mortality. In line with this fact, additional predictors of mortality included older age, male sex, increased comorbidities, and presentations suggestive of an acute abdomen. Taken together, our findings provide a robust representation of small bowel volvuli in U.S. adults in the 21st century.
Our findings corroborate and expand upon seven major case series of SBV in adults that have been reported by American [10, 15-17] and European [1, 11, 18] groups. These include reports from the Massachusetts General Hospital and Mayo Clinic in the United States.[10, 15] These studies ranged in length from 10 to 30 years with an average of 19.6 years. In these series, a total of 354 patients were reported (median 40, range: 4-129) with an average of 0.13 to 5.7 cases per year. In the current series, we observed 20,680 hospitalizations for SBV over 13 years. The prior studies reported mean ages from 45 to 67 years old. Similarly, the mean age in our study was 66.0 ± 19.4 years. Moreover, consistent with our sex distribution of 56.6% females, Welch,[1] Ruiz-Tovar [11] and Roggo [10] reported sex distributions with 52.8%, 53.5%, and 54% females, respectively. In these seven studies, 35.3% (range: 10.0-89.5%) were primary volvuli and 64.7% (range: 10.5-85.7%) were secondary volvuli. Four of the studies reported the mortality associated with non-viable bowel. In this latter subgroup, the mortality ranged from 17% to 61%, while the overall mortality ranged from 9% to 33%. Consistent with these findings, in the current study, we determined that acute vascular insufficiency was an independent predictor of mortality and we observed an overall mortality rate of 7.92%. Our current findings corroborate and expand upon these earlier reports.
The major strengths of our study include the large sample size, which is 58.4-fold larger than the combined seven major American (N=4 [10, 15-17]) and European (N=3 [1, 11, 18]) studies, as well as is its broad applicability; this is the first study to utilize a national database to characterize the nature of SBV. Since the NIS database samples 20% of all hospitals in the United States, we can estimate current trends and management of SBV and SBV+IM at a national level as opposed to previous studies that have been limited to single institution series of less than 129 patients.[10, 15-17] Additionally, we note that year of diagnosis does not affect mortality, despite a number of developments that have come about during our study period which have improved surgical outcomes, including the introduction of clinical pathways and the establishment of quality care initiatives, such as perioperative antibiotic administration.
The major limitation of our study is the lack of specificity of ICD-9 codes for SBV. We addressed this limitation by excluding all patients who had undergone gastric or colonic procedures in order to isolate patients with SBV; however, this approach possibly excludes some patients with SBV, leading to potential underestimation, which we preferred to overestimation by including gastric and colonic procedures. Along this line, large databases, such as the NIS, are also susceptible to coding discrepancies and missing data. These are unlikely to cause significant biases, as they would be random and evenly distributed across all groups. An additional limitation is the lack of coding for all presenting signs and symptoms. We elected to utilize common signs of an acute abdomen upon presentation. Given the infinite number of potential presentations and codes, we were unable to clearly identify all presentations. Finally using NIS, we are unable to clearly differentiate primary from secondary volvuli, a distinction commonly made in institutional case series. Primary volvuli are defined as having no underlying cause. These are most common in children and young adults, while secondary volvuli are due to congenital or acquired lesions.[6] In our case, we can assume that many are secondary and caused by adhesions because 32.44% of patients were managed with adhesiolysis. However, others have reported additional causes including internal hernias, tumors, mesenteric lymphadenopathy and masses, Meckel’s diverticula, pregnancy, endometriosis, abscesses, peritoneal mycobacterial disease, aneurysms, and hematomas.[19] Determining each individual secondary cause is beyond the scope or our current report.
Conclusions
In conclusion, while relatively uncommon compared to other causes of bowel obstructions, surgeons should be cognizant of the potential for SBV and SBV+IM in the adult population, especially when imaging findings are concerning for these diagnoses. Waiting for signs of peritonitis, intestinal ischemia, coagulopathy, and/or failure of non-operative management should be avoided in order to improve outcomes. Taken together, we provide strong evidence that timely diagnosis and operative management should be utilized for the treatment of medically fit adult patients presenting with SBV, including those with SBV and IM.
Supplementary Material
Footnotes
Author Contributions: All authors had full access to all the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis. Study concept and design: All authors. Acquisition of data: All authors. Analysis and interpretation of data: All authors. Drafting of the manuscript: All authors. Critical revision of the manuscript for important intellectual content: All authors. Statistical analysis: All authors.
Conflict of Interest Disclosures: None reported.
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Contributor Information
Taylor M. Coe, Email: tcoe@ucsd.edu.
David C. Chang, Email: DCHANG8@mgh.harvard.edu.
References
- 1.Welch GH, Anderson JR. Volvulus of the small intestine in adults. World J Surg. 1986;10(3):496–500. doi: 10.1007/BF01655319. [DOI] [PubMed] [Google Scholar]
- 2.Strouse PJ. Disorders of intestinal rotation and fixation (“malrotation”) Pediatr Radiol. 2004;34(11):837–51. doi: 10.1007/s00247-004-1279-4. [DOI] [PubMed] [Google Scholar]
- 3.Torres AM, Ziegler MM. Malrotation of the intestine. World J Surg. 1993;17(3):326–31. doi: 10.1007/BF01658699. [DOI] [PubMed] [Google Scholar]
- 4.Emanuwa OF, Ayantunde AA, Davies TW. Midgut malrotation first presenting as acute bowel obstruction in adulthood: a case report and literature review. World J Emerg Surg. 2011;6(1):22. doi: 10.1186/1749-7922-6-22. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 5.Moldrem AW, et al. Late presentation of intestinal malrotation: an argument for elective repair. World J Surg. 2008;32(7):1426–31. doi: 10.1007/s00268-008-9490-3. [DOI] [PubMed] [Google Scholar]
- 6.Vaez-Zadeh K, Dutz W, Nowrooz-Zadeh M. Volvulus of the small intestine in adults: a study of predisposing factors. Ann Surg. 1969;169(2):265–71. doi: 10.1097/00000658-196902000-00014. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 7.Cathcart RS, 3rd, et al. Surgical treatment of midgut nonrotation in the adult patient. Surg Gynecol Obstet. 1981;152(2):207–10. [PubMed] [Google Scholar]
- 8.Gulati SM, et al. Volvulus of the small intestine in India. Am J Surg. 1973;126(5):661–4. doi: 10.1016/s0002-9610(73)80017-0. [DOI] [PubMed] [Google Scholar]
- 9.Iwuagwu O, D G. Small Bowel Volvulus: a review. J R Coll Surg Edinb. 1999;44(3):150–155. [PubMed] [Google Scholar]
- 10.Roggo A, Ottinger LW. Acute small bowel volvulus in adults. A sporadic form of strangulating intestinal obstruction. Ann Surg. 1992;216(2):135–41. doi: 10.1097/00000658-199208000-00003. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 11.Ruiz-Tovar J, et al. Volvulus of the small bowel in adults. Am Surg. 2009;75(12):1179–82. [PubMed] [Google Scholar]
- 12.Quality, A.f.H.R.a. Overview of the Nationwide Inpatient Sample (NIS) [January 15, 2014]; Available at: http://www.hcup-us.ahrq.gov/nisoverview.jsp.
- 13.Halabi WJ, et al. Colonic volvulus in the United States: trends, outcomes, and predictors of mortality. Ann Surg. 2014;259(2):293–301. doi: 10.1097/SLA.0b013e31828c88ac. [DOI] [PubMed] [Google Scholar]
- 14.Charlson ME, et al. A new method of classifying prognostic comorbidity in longitudinal studies: development and validation. J Chronic Dis. 1987;40(5):373–83. doi: 10.1016/0021-9681(87)90171-8. [DOI] [PubMed] [Google Scholar]
- 15.Frazee RC, et al. Volvulus of the small intestine. Ann Surg. 1988;208(5):565–8. doi: 10.1097/00000658-198811000-00004. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 16.Juler GL, Stemmer EA, Connolly JE. Preoperative diagnosis of small bowel volvulus in adults. Am J Gastroenterol. 1971;56(3):235–47. [PubMed] [Google Scholar]
- 17.Moretz WH, Morton JJ. Acute volvulus of small intestine; analysis of 36 cases. Ann Surg. 1950;132(5):899–912. doi: 10.1097/00000658-195011000-00004. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 18.Svane S. Volvulus of the Entire Small Intestine in Adults. Four Cases Without Anomalies of Intestinal Rotation. Acta Chir Scand. 1965;129:649–55. [PubMed] [Google Scholar]
- 19.Papadimitriou G, Marinis A, Papakonstantinou A. Primary midgut volvulus in adults: report of two cases and review of the literature. J Gastrointest Surg. 2011;15(10):1889–92. doi: 10.1007/s11605-011-1534-6. [DOI] [PubMed] [Google Scholar]
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