a b s t r a c t

Background: Abdominal radiographs are often obtained in ED patients with suspected constipation, although their utility in adults is not well understood. We sought to compare ED management when an abdominal radio- graph is and is not obtained.

Methods: We performed a retrospective chart review study of adult ED patients with a chief complaint of consti- pation from 2010 through 2016. Trained abstractors recorded radiologic tests ordered, treatments received, and final diagnosis. We determined the physician interpretation of the abdominal radiograph and its use in clinical decision making.

Results: Of 1142 eligible patients, 481 (42%) patients underwent Abdominal radiography. Stool burden rated moderate or large was observed in 271 patients (46%). Sixteen patients (3%) were diagnosed with Small bowel obstruction; 15/16 of these patients had high risk features such as old age, complex surgical history, history of small bowel obstruction, abdominal malignancy, or presented with vomiting or inability to pass flatus. Of the 197 patients with no or mild stool burden or normal radiograph, 109 (55%) were diagnosed with constipation and 89 (45%) received constipation treatment in the ED. Conversely, of the 271 patients with moderate or greater stool burden, 114 (42%) received no treatment for constipation in the ED and 104 (38%) were prescribed no dis- charge medications for constipation; 77 of these 271 patients (28%) were diagnosed with something other than constipation.

Conclusion: Plain abdominal radiography did not appear to significantly affect the ED management of patients presenting with constipation; it was common for patients to receive treatment that was in direct opposition to radiographic findings. Though a small number of patients had concerning diagnoses identified on plain radiogra- phy, the history and physical examination should have sufficiently excluded simple constipation, prompting an alternate Diagnostic approach. Fecal loading on radiography does not preclude a more serious diagnosis. In con- clusion, abdominal radiography appears to have low value in patients with constipation.

(C) 2019

Introduction

Constipation is a common chief complaint in the emergency depart- ment (ED); ED visits related to constipation occur N700,000 times per year in the United States, with an annual cost of N1.6 billion dollars [1]. According to expert opinion, many ED patients presenting with con- stipation can be managed based on the history and physical exam alone, without radiographic testing [2]. However, because definitions and per- ceptions of constipation might differ between the patient and physician [3], sometimes patients with a chief complaint of constipation actually have an alternate, more sinister, diagnosis [2]. For this reason, there is

* Corresponding author at: Department of Emergency Medicine, 701 Park Ave S, Mail Stop R2, Minneapolis, MN 55415, USA.

E-mail address: [email protected] (B.E. Driver).

significant variation in clinical practice between physicians regarding the use of plain abdominal radiography in this patient population. Ab- dominal radiography is ostensibly performed to “rule-in” or “rule-out” constipation. Some clinicians obtain abdominal radiographs in all pa- tients presenting with constipation, some never obtain radiographs, and still others perform radiography when high risk features are pres- ent. There is no established consensus or standard of care as to whether or when abdominal radiography should be performed.

There are potential downsides to the use of abdominal radiography in this patient population. The presence of fecal loading on radiography does not exclude other pathology, [4] which sometimes leads to misdi- agnosis of constipation when a more serious diagnosis is present [5,6]. Fecal loading on radiography does not correspond well to stool colonic transit time or the patient’s symptoms [7]. Additionally, the agreement between raters of the degree of constipation on radiography has been

https://doi.org/10.1016/j.ajem.2019.158377

0735-6757/(C) 2019

found repeatedly to be poor [7-9]. Ionizing radiation is also a potential downside if the test is of little utility.

Most existing literature of abdominal radiography and constipation has examined children, and to our knowledge there are no studies of the utility of abdominal radiography in the setting of suspected consti- pation in adult ED patients. Therefore, in adult ED patients with a chief complaint of constipation, we sought to compare ED management when an abdominal radiograph is and is not obtained.

Materials and methods

Study design and setting

This was a retrospective, observational study conducted in the ED of an urban Level 1 trauma center that cares for approximately 100,000 pa- tients annually. There is no ED protocol for the care of patients with suspected constipation. The institutional review board at Hennepin County Medical Center approved this study.

Selection of participants

Adult ED patients (>=18 years old) with a chief complaint of constipa- tion from December 2010 through December 2016 were identified in the electronic medical record. We excluded patients who underwent

calculated. We used Stata (Version 15, Stata Corporation, College Sta- tion, TX) for all data analyses.

Results

During the study period 1218 patients met initial inclusion criteria; 76 underwent computed tomography only or before abdominal radiog- raphy and were excluded, leaving 1142 for analysis. Of these, 481 (42%) had an abdominal radiograph and 661 (58%) did not. The median age was 46 y (IQR 30-61 y) and 548 were women (48%). Baseline character- istics are presented in Table 1.

Abdominal radiograph findings are presented in Table 2. Stool bur- den rated moderate or large was observed by the radiologist or emer- gency physician in 271 patients (46%). There were 87 patients (18%) with other abnormal findings observed in the radiograph, including 33 (7%) with small bowel obstruction (Table 3). Of the 33 with small bowel obstruction seen on abdominal radiography, only 16 were diag- nosed with small bowel obstruction by the treating physician; the re- mainder were diagnosed with constipation (N = 11), ileus (N = 2), incarcerated hernia (N = 2), and abdominal pain (N = 2).

Table 1

Baseline characteristics.

computed tomography only or computed tomography prior to radiog- raphy, as this represents a patient population who the physician has deemed not to have simple constipation. We used the chief complaint

Variable Radiograph

obtained (N = 481)

No radiograph obtained

(N = 661)

of constipation rather than a final diagnosis of constipation in order to examine a population of patients who the physician considered consti- pation as a diagnosis from the outset; examining patients with a diagno- sis of constipation would exclude those who were at first suspected to have constipation but were later found to have an alternate diagnosis.

Methods of measurement

Using the electronic medical record (Epic Systems, Verona, WI), trained abstractors reviewed each eligible chart, including physician and nursing notes, imaging reports, ED orders, and the discharge plan. We recorded patient demographics, radiologic tests ordered and their final results, treatments received in the ED, the final diagnosis, and dis- charge prescriptions. We also reviewed physician notes to determine how the abdominal radiograph was interpreted and how it was used in the clinical decision making for the patient. For abdominal radio- graphs, we recorded the reported radiographic stool burden (none, small, moderate or greater, or no mention of stool burden), as well as other abnormal radiographic findings including both gastrointestinal and non-gastrointestinal pathology. We reviewed further the charts of those diagnosed with small or large bowel obstructions to describe their clinical history and presentation.

Outcome measures

Main outcomes of the study included whether treatment for consti- pation was administered in the ED and whether constipation was the primary ED diagnosis.

Age, median (IQR) – y 53 (36-65) 41 (27-57)

Male gender – no. (%) 262 (54) 332 (50)

Race – no. (%)

Native American 12 (2) 25 (4)

Asian 22 (5) 13 (2)

African American 226 (47) 336 (51)

Hispanic 39 (8) 55 (8)

White 171 (36) 211 (32)

Other/unknown 11 (2) 21 (3)

Comorbidities – no. (%)

Hypertension 148 (31) 159 (24)

Diabetes mellitus 107 (21) 136 (21)

Coronary artery disease 25 (5) 26 (4)

Heart failure 15 (3) 20 (3)

History of cerebrovascular accident 15 (3) 21 (3)

Chronic obstructive pulmonary disease 22 (5) 25 (4)

Liver disease/cirrhosis 8 (2) 2 (b1)

Chronic kidney disease 25 (5) 19 (3)

Initial vital signs, median (IQR)

Heart rate – beats per min 88 (74-100) 86 (75-98)

Systolic blood pressure – mm Hg 131 (120-146) 128 (116-142)

Temperature – degrees C 36.7 (36.4-36.9) 36.7 (36.4-36.9)

Urinalysis results – no. (%)

Positive nitrites 11/152 (7) 12/123 (10)

Proteinuria 7/152 (5) 11/123 (9) Red blood cells N0-5 per hpf 24/152 (16) 17/123 (14) White blood cells N0-5 per hpf 31/152 (20) 38/123 (31)

Serum laboratory results – median (IQR)^a

Creatinine – mg/dL 0.9 (0.7-1.0) 0.8 (0.6-1.1)

Hemoglobin – g/dL 12.9 (11.7-14.3) 12.7 (11.2-13.8)

White blood cell count –

thousand/cubic mm

8.2 (6.3-10.5) 8.8 (6.6-11.2)

Data analysis

All data analyses are descriptive. Baseline characteristics, radiogra- phy findings, and ED management are described using counts and pro- portions. ED management, diagnosis, and discharge prescriptions are stratified by whether an abdominal radiograph was obtained, and dif- ferences are presented as absolute differences with associated 95% con- fidence intervals. We compared ED management, diagnosis, and disposition using the chi square test. No a priori sample size was

Sodium – meq/L 138 (136-140) 139 (137-140)

Potassium – meq/L 3.8 (3.6-4.2) 3.9 (3.6-4.2)

total carbon dioxide – meq/L 26 (24-28) 26 (23-28)

Lactate – mmol/L 1.4 (1-1.9) 2 (1.7-2.2)

hpf, high powered field.

This table displays demographic information, stratified by whether an abdominal radio- graph was obtained. Variables statistically different between groups included age, Asian ethnicity, hypertension, chronic kidney disease, and white blood cells N0-5 per hpf.

^a Creatinine, sodium, potassium, and total carbon dioxide obtained in 269 patients, hemoglobin and white blood cell count in 217 patients, and lactate in 69 patients.

Table 2

Abdominal radiograph findings.

Variable Final

radiology read

Radiograph findings documented in ED physician note

The clinical details for those diagnosed with a small or large bowel obstruction are displayed in Supplementary Table 1. Those with a small bowel obstruction tended to be older (median age 56 [IQR 44-65]), have a complex surgical history (10/16, 63%), history of small bowel obstruction (7/16, 44%), abdominal malignancy (3/16, 19%), or present with vomiting (10/16, 63%) or inability to pass flatus (4/16, 25%). Only 1 of the 16 patients had none of these features. This patient

Normal radiograph – no. (%) 185 (38) 106 (22)

was admitted to the hospital but did not need nasogastric tube place-

Abnormal finding, excluding moderate or greater stool burden^a – no. (%)

87 (18) 58 (12)

ment or surgical intervention. She was discharged 40 h after admission.

This table displays the findings for the 481 patients who had an abdominal radiograph ob- tained during the ED encounter. The “radiology read” column displays the final read by the attending radiologist. The “Radiograph findings documented in ED note” column displays how the findings of the radiograph were documented in the ED note, whether from per- sonal review of the images or from the reading the radiology read. Patients could have both mention of a stool burden and an abnormal finding, hence the sum for each column exceeds 481.

^a See Table 3 for the abnormal findings.

ED treatment, diagnosis, disposition, and whether a bowel regimen was prescribed are displayed in Table 4. Those with a radiograph ob- tained were more likely to receive treatment in the ED for constipation (55% vs 44%), less likely to be diagnosed with constipation (59% vs 65%), and more likely to be diagnosed with abdominal pain, small bowel ob- struction, or large bowel obstruction, and to be admitted to the hospital (18% vs 4%).

Of the 197 patients with no or mild stool burden or normal radio- graph, 109 (55%) were diagnosed with constipation and 89 (45%) re- ceived an enema, suppository, or magnesium citrate in the ED-in direct opposition to the radiographic findings. Conversely, of the 271 eventually discharged patients with moderate or greater stool burden as documented in the final radiology read or emergency physician note, 114 (42%) received no treatment for constipation in the ED and 104 (38%) were prescribed no discharge medications for constipation; 77 of these 271 patients (28%) were diagnosed with something other than constipation at the end of the encounter.

Table 3

Abnormal radiographic findings.

Finding Number (% with finding/no. patients with

radiograph obtained)

Small bowel obstruction^a 33 (7)

Fecal impaction 10 (2)

Large bowel obstruction 6 (1)

Other GI problems 19 (4)

Ileus 6 (1)

Gas-filled/dilated/distended loops 6 (1)

Air-fluid levels 4 (1)

Ascites 1 (b1)

We included only patients with a self-reported chief complaint of constipation; this population differs slightly from patients thought by the physician to have constipation at the initial evaluation, or those eventually diagnosed with constipation. This population includes both high and low-risk patients, and the results would probably be substan- tially different if we included only patients with a final diagnosis of con- stipation. We only abstracted for outcomes ascertained at the index ED encounter. It is possible that some patients discharged with a benign di- agnosis were later found to have a more serious diagnosis; in prior pe- diatric literature this has occurred in b1% of encounters, and highlights the folly of overreliance on abdominal radiography to diagnose consti- pation [6].

5. Discussion

Stool burden – no. (%)
Minimal or small Moderate or large	12 (2) 220 (46)	17 (4) 263 (55)	4. Limitations
No mention of stool burden	249 (52)	201 (42)

In this study of 1142 patients, we were unable to discern any true utility to the abdominal radiograph in the setting of suspected constipa- tion apart from the detection of small bowel obstruction in high-risk pa- tients. While there were small differences between study groups, including slightly a higher rate of ED treatment for constipation and, paradoxically, a lower rate constipation diagnosis in those who underwent abdominal radiography, these differences are of unclear sig- nificance and perhaps are related to physician practice patterns rather than related to the outcome of the radiologic test.

For the abdominal radiograph to have value in the setting of suspected constipation, the radiograph should establish the diagnosis of constipation or exclude it, or at least provide some reliable measure of the degree of constipation. In the current study, there was no clear as- sociation between findings or absence of constipation and ED treat- ment; patients without fecal loading on radiography commonly received treatment for constipation, conversely, patients with fecal loading commonly had no treatment for constipation. Therefore, the ra- diograph did not seem to dictate management. Rather, physician judg- ment often overrode radiographic findings.

This practice may be prudent. The radiographic degree of fecal load- ing does not correlate well with constipation symptoms or stool colonic transit time, [7] bolstering the case that physician judgment should su- persede radiographic findings. Furthermore, Interrater agreement of

RLQ calcification (possible ovarian

dermoid)

1 (b1)

fecal loading on radiography is poor to fair, even when formal rating

scales are used [7-9]. These data, when synthesized, suggest that radio-

AAA battery in sigmoid colon 1 (b1)

Non-GI findings 19 (4)

Pleural effusion 4 (1)

Nephrolithiasis 4 (1)

Other^b 12 (2)

This table displays other abnormal findings for the 87 (of 481 with a radiograph obtained) patients with an abnormality seen, apart from findings related to stool burden.

^a Of the 33 patients with a final read of small bowel obstruction on the abdominal ra- diograph, only 16 were diagnosed with small bowel obstruction by the treating physician during the encounter. The other 17 were diagnosed with constipation (N = 11), ileus (N

= 2), incarcerated hernia (N = 2), and abdominal pain (N = 2).

^b Other non-GI findings included (each finding had one patient): punctate kidney cal- cification, vascular calcifications, ureteral stent present, inferior vena cava filter present, fractured cerclage wire, Ankylosing spondylitis, scoliosis, compression deformity of L4, disc height loss L5-S1, protrusio hip defects, hiatal hernia, pneumatosis of the left lateral rectal wall.

graphic fecal loading is difficult to objectively determine and does not necessarily aid in the clinical diagnosis of constipation. Constipation is a clinical diagnosis and treatment should be based on the history and examination [2,4]. If constipation is clinically suspected, but uncertain, administration of an enema in the ED may assist in the diagnosis; pa- tients who have a large bowel movement and feel significantly better can be presumed to have constipation; alternate diagnoses can be ex- plored for patients who don’t improve after an enema.

In this cohort, it is difficult to reason why treatment rates for consti- pation were slightly higher in those who underwent radiography. Per- haps fecal loading on radiography prompted treatment where it otherwise would not have been given, a questionable practice as fecal loading does not equate to colonic transit time or symptoms.

Table 4

ED management and diagnosis.

Variable	Radiograph obtained (N = 481)	No radiograph obtained (N = 661)	Difference	P-value
ED treatment, any – no. (%)	264 (55)	289 (44)	11% (5 to 17%)	b0.001
Enema	226 (47)	239 (36)	11% (5 to 17%)	b0.001
Manual disimpaction	43 (9)	45 (7)	2% (-1 to 5%)	0.18
Suppository	16 (3)	17 (3)	1% (-1% to 3%)	0.45
Magnesium citrate Final diagnosisa – no. (%)	23 (5)	26 (4)	1% (-2% to 3%)	0.49
Constipation	282 (59)	428 (65)	-6% (-12 to 0%)	0.03
Abdominal pain	31 (6)	21 (3)	3% (1 to 6%)	0.009
Small bowel obstruction	16 (3)	0 (0)	3% (2 to 5%)	b0.001
Large bowel obstruction	6 (1)	0 (0)	1% (0 to 2%)	0.004
Fecal impaction	3 (b1)	3 (b1)	0% (-1 to 1%)	0.70
Other	143 (30)	209 (32)	-2% (-7% to 4%)	0.50
Discharged from the ED – no. (%)	398 (83)	636 (96)	-14% (-18 to -10%)	b0.001
Discharged with bowel regimen, any – no. (%)	226 (47)	356 (54)	-7% (-12 to -1%)	0.02

^a Final diagnosis lists the primary ED diagnosis. The most common diagnoses are displayed. There were no diagnoses of appendicitis, cholecystitis, or diverticulitis.

Additionally, the presence of fecal loading does not preclude the co- presence of more serious diagnoses.

These results are consistent with prior work examining pediatric pa- tients with constipation [5,6,10]. To our knowledge, no study has found that abdominal radiographs are useful for diagnosing constipation. Some argue that they should never be obtained, [10] others have found the use of radiographs is associated with misdiagnosis of more se- rious pathology [5,6]. Freedman et al., studying 3685 children diagnosed with constipation in the ED, showed that 7 day revisits resulting in hos- pitalization or a procedure were more common when a radiograph was obtained or abdominal pain or tenderness was present, emphasizing that the presence of stool on abdominal radiography does not preclude a more serious diagnosis [6].

Some may cite other potential benefits of abdominal radiography in this population, including the detection of alternate diagnoses or inci- dental findings. In this study, abnormal findings were present in 87 pa- tients (18% of those with a radiograph), the most common findings being fecal impaction, small and large bowel obstruction, and ileus. These findings may seem frequent, but most of these diagnoses should be clinically apparent and not confused with simple constipation. Fecal impaction is easily diagnosed by rectal examination; ileus has spe- cific historical clues. Judging from the narratives of patients diagnosed with small bowel obstruction (Supplementary Table 1), those with small and large bowel obstructions generally were older, had complex surgical histories, abdominal malignancies, prior bowel obstructions, or had historical features more consistent with diagnoses more serious than constipation, such as vomiting or inability to pass flatus. Other in- cidental findings discovered in this cohort were largely clinically insig- nificant and not worthy of an indication to obtain abdominal radiography.

Patients with higher risk features, including significant abdominal pain or tenderness, moderate pain or tenderness that does not improve with an enema, complex surgical histories, recurrent bowel obstruc- tions, or concerning historical features such as vomiting or inability to pass flatus, should likely undergo computed tomography rather than Plain radiography to determine if a serious diagnosis is present. If recur- rent small bowel obstruction is suspected, however, it may be reason- able to use plain abdominal radiography as a preliminary test, moving to computed tomography if the radiograph is negative and suspicion re- mains high [11]. If the plain radiograph reveals obstruction, further test- ing may not be required if Bowel ischemia is not clinically suspected. For other diagnoses existing data and expert opinion agree that the role of plain abdominal radiography is limited and computed tomography or ultrasound are better imaging modalities, depending on what diagnosis is suspected [2,11-13].

In summary, plain abdominal radiography did not appear to signifi- cantly affect the management of patients presenting to the ED with

constipation; it was common for patients to receive treatment that was in direct opposition to radiographic findings. Though a small num- ber of patients had concerning diagnoses identified on plain radiogra- phy, the history and physical examination should have sufficiently excluded simple constipation as the reason for their visit, prompting an alternate diagnostic approach. Fecal loading on radiography does not preclude a more serious diagnosis. In conclusion, abdominal radiog- raphy appears to have low value in patients with constipation.

Supplementary data to this article can be found online at https://doi. org/10.1016/j.ajem.2019.158377.

Previous presentation

None.

Declaration of Competing Interest

This was an unfunded investigation. No authors have any conflicts of interest to report.

Acknowledgements

None.

References

1. Sommers T, Corban C, Sengupta N, Jones M, Cheng V, Bollom A, et al. Emergency de- partment burden of constipation in the United States from 2006 to 2011. Am J Gastroenterol 2015;110(4):572-9 Apr.
2. Shoenberger JM, Walls RM. Constipation. In: Hockberger RS, Gausche-Hill M, editors. Rosen’s emergency medicine: concepts and clinical practice. Elsevier; 2018.

   p. 257-61 [e1].

   Herz MJ, Kahan E, Zalevski S, Aframian R, Kuznitz D, Reichman S. Constipation: a dif- ferent entity for patients and doctors. Fam Pract 1996;13(2):156-9 Apr.

3. Loo JT, Duddalwar V, Chen FK, Tejura T, Lekht I, Gulati M. Abdominal radiograph pearls and pitfalls for the emergency department radiologist: a pictorial review. Abdom Radiol (NY) 2017;42(4):987-1019 Apr.
4. Freedman SB, Rodean J, Hall M, Alpern ER, Aronson PL, Simon HK, et al. Delayed di- agnoses in children with constipation: multicenter retrospective cohort study. J Pediatr 2017;186:87-94.e16 Jul.
5. Freedman SB, Thull-Freedman J, Manson D, Rowe MF, Rumantir M, Eltorki M, et al. Pediatric abdominal radiograph use, constipation, and significant misdiagnoses. J Pediatr 2014;164(1) Jan. [83-8.e2].
6. Cowlam S, Vinayagam R, Khan U, Marsden S, Minty I, Moncur P, et al. Blinded com- parison of faecal loading on plain radiography versus radio-opaque marker transit studies in the assessment of constipation. Clin Radiol 2008;63(12):1326-31 Dec.
7. Moylan S, Armstrong J, Diaz-Saldano D, Saker M, Yerkes EB, Lindgren BW. Are ab- dominal X-rays a reliable way to assess for constipation? J Urol 2010;184(Suppl. 4):1692-8 Oct.
8. da Cunha TB, Tahan S, Soares MF de F, Lederman HM, de Morais MB. Abdominal ra- diograph in the assessment of fecal impaction in children with functional constipa- tion: comparing three scoring systems. J Pediatr 2012;88(4):317-22 Jul.
9. Norbedo S, Bassanese G, Barbieri F, Barbi E. Acute abdominal pain: recognition and management of constipation in the emergency department. Pediatr Emerg Care 2017;33(10):e75-8 Oct.
10. Smith JE, Hall EJ. The use of plain abdominal x-rays in the emergency department. Emerg Med J 2009;26(3):160-3 Mar.
11. McNamara R, Dean AJ. Approach to acute abdominal pain. Emerg Med Clin North Am May 2011;29(2):159-73 vii.
12. van Randen A, Lameris W, Luitse JSK, Gorzeman M, Hesselink EJ, Dolmans DEJGJ, et al. The role of plain radiographs in patients with acute abdominal pain at the ED. Am J Emerg Med Jul 2011;29(6):582-9 [e2].