Utility of balloon expulsion test in patients with constipation: Preliminary results in a single center

==Summary==

====Background====

Pelvic floor dyssynergia can be a cause of idiopathic constipation. Although pelvic floor dyssynergia can be diagnosed by rectal balloon expulsion (BE) and anorectal manometry, the utility of BE in the evaluation of constipation in clinical practice remains to be determined. To this end, we examined the role of BE among different body positions in Taiwanese people with constipation.

====Methods====

Fourteen Taiwanese adults (age range, 19–61 years), including six healthy volunteers (4 male, 2 female) and eight patients with chronic constipation (1 male, 7 female) underwent solid-state anorectal manometry and BE. The demographic data of all individuals were recorded at enrollment.

====Results====

Compared to healthy volunteers, patients with chronic constipation had a numerically lower threshold for mean resting pressure (''p''  = 0.052), squeeze pressure, maximal squeeze pressure, and lower threshold volumes for urge, but higher threshold pressures for compliance. Successful BE seemed to be associated with lower mean resting pressure (''p''  = 0.061), lower mean threshold volumes for urge, and higher mean maximal squeeze pressure for compliance. Although patients with chronic constipation had a numerically lower successful rate of rectal BE than healthy controls, the differences did not reach statistical significance.          

====Conclusion====

In Taiwanese individuals, results of BE seems consistent with anorectal manometry parameters, and patients with chronic constipation have a trend of lower successful rate of rectal BE than healthy controls. However, future work to confirm the use of BE in differentiating subtypes of chronic constipation is needed.

==Keywords==

Anorectal manometry ; Balloon expulsion ; Constipation ; Pelvic floor dyssynergia ; Taiwan

==Introduction==

Pelvic floor dyssynergia (PFD) can be a cause of idiopathic constipation, and is defined as paradoxical contraction or failure to relax the pelvic floor muscles during attempts to defecate [[#bib1|[1]]] . Identification of PFD is of value because it has therapeutic implications in clinical practice, and at least, two-thirds of patients may learn to relax the pelvic floor muscles appropriately when provided with biofeedback training [[#bib1|[1]]] . Although a focused history and digital examination are key components in diagnosing PFD, physiological findings, including anorectal manometry and rectal balloon expulsion (BE) test, may help in categorization and management of patients [[#bib2|[2]]] .      

BE is a test performed by measuring the time required to expel a rectal balloon filled with water or air and is a useful, sensitive, and specific test for evacuation disorders [[#bib3|[3]]] ; [[#bib4|[4]]]  ;  [[#bib5|[5]]] . Compared to anorectal manometry [[#bib6|[6]]] , BE is a simpler procedure to identify impaired evacuation in constipated patients and has been recommended as part of the diagnostic workup of PFD or for excluding constipated patients without PFD. Usually, patients with a normal BE result may not need to receive other functional studies, which are more expensive and difficult to perform, to rule out PFD. Therefore, BE is a useful screening test in clinical practice for the evaluation of constipation [[#bib3|[3]]] .      

Although several Western studies have examined the clinical utility of BE in patients with constipation, its use in Taiwanese patients remains largely unknown. To this end, we intended to investigate the role of BE among different body positions in Taiwanese constipated patients.

==Methods==

===Ethical considerations===

The study was performed in accordance with the principles of the Declaration of Helsinki and was approved by the Ethical Committee of the Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Hualien, Taiwan. Informed consent was obtained from each patient and control at the time of initial interview.

===Participants===

A total of 14 Taiwanese volunteers, eight with chronic constipation (patients were required to comply with the relevant diagnostic Rome III criteria) and six healthy individuals, participated in this study from January 1, 2014 to June 30, 2015. All individuals enrolled had to meet the following inclusion criteria: (1) both men and women aged 18–65 years; (2) not taking drugs that promote or inhibit defecation (e.g., laxative and antidiarrheal drugs), agents that increase or decrease gastrointestinal motility, or diet pills within a week of the study; and (3) normal hearing and able to cope with those tests. All individuals were enrolled from gastroenterology clinics of Hualien Tzu Chi Hospital and interviewed about their general health and gastrointestinal symptoms. Chronic constipation was diagnosed based on Rome III criteria [[#bib1|[1]]]  ;  [[#bib7|[7]]] . In brief, a patient must have experienced: (1) at least two of the following symptoms for the past 3 months with symptom onset at least 6 months prior to diagnosis: (i) straining during at least 25% of defecations; (ii) lumpy or hard stools in at least 25% of defecations; (iii) sensation of incomplete evacuation for at least 25% of defecations; (iv) sensation of anorectal obstruction/blockage for at least 25% of defecations; (v) manual maneuvers to facilitate at least 25% of defecations (e.g., digital evacuation, support of the pelvic floor); and (vi) fewer than three defecations per week; (2) loose stools rarely present without the use of laxatives; and (3) insufficient criteria for irritable bowel syndrome. Of note, patients with PFD were not excluded from the study.      

Healthy volunteers were enrolled from a university student population without a history of an underlying medical condition, previous gastrointestinal surgery, or gastrointestinal symptoms. All participants were evaluated and confirmed by a questionnaire that was used to assess any abnormality in the bowel and anorectal function. Normal anorectal and bowel function was defined as the passage of stools not less than three times per week or not more than three times per day, no difficulty or pain during defecation, and no current bowel habit change. None of the women had a history of abdominal surgery. None of the participants took any drug that may have affected gastrointestinal motility at least 48 hours prior to the study.

===Anorectal manometry and BE test===

All participants received a Fleets enema (C.B. Fleet company, Lynchburg, VA, USA) to evacuate the rectum before the test. Fleet contains sodium biphosphate and sodium phosphate and is a combination medicine used in adults to clean the bowel before colonoscopy. The probe was a 4.5 mm diameter, solid state catheter with multiple pressure transducers (Sandhill Scientific, Highlands Ranch, CO, USA), and a lumen for balloon inflation. A 5-cm balloon was tied to the distal end of the catheter. The lubricated catheter was introduced into the rectum as patients lay in the left lateral position with their hips and knees flexed to 90°. Average resting and squeeze pressures were recorded by the stationary pull-through technique. The threshold volume for rectoanal inhibitory reflexes was assessed by distending the rectal balloon in progressive 10-mL decrements, starting at 60 mL, until anal sphincter relaxation was observed at the lowest volume of distension. The rectal sensation was evaluated with the rectal balloon inflated at an interval of 10 mL until the participant reported the first sensation. The balloon volume was then increased by steps of 30 mL so that participants experienced the sensations of the urge to defecate as well as maximum distension. The threshold volumes for inducing these sensations were recorded. Rectal compliance for each balloon distention was derived from the slope of the volume–pressure curve.

BE test was conducted as part of anorectal manometry. The balloon was inflated until the patients felt a desire to defecate. Patients were then asked to evacuate the balloon in the left lateral decubitus, sitting and squat position in privacy. Each position lasted for 1 minute. A successful BE indicated that the patient could expel the balloon within 1 minute. If patients had successful BE in the former position, their results in the latter position were not evaluated [[#bib8|[8]]] .      

===Anal sphincter function===

Anal sphincter function is assessed by measurement of resting sphincter pressure, squeeze sphincter pressure, and the functional length of the anal canal. Normal resting pressure is 40–80 mmHg, squeeze pressure is normally 80–160 mmHg, and maximum squeeze pressure is defined as the difference between the intrarectal pressure and the highest pressure that is recorded at any level within the anal canal during the squeeze maneuver [[#bib9|[9]]]  ;  [[#bib10|[10]]] .      

===Statistical analysis===

The manometric data are expressed as mean and (range) unless otherwise stated. Statistical comparisons were assessed using Students ''t''  test or nonparametric test as appropriate. Correlations were studied with the Pearson test. A ''p''  value < 0.05 was considered statistically significant.      

==Results==

===Demographic features===

A total of 14 Taiwanese adults were enrolled, including six healthy volunteers and eight patients with chronic constipation, and underwent measurements of solid-state anorectal manometry and BE. Among the six healthy volunteers, four were male and two were female, and the average age was 27 years (range, 20–48 years). In patients with chronic constipation, seven were female and one was male, and the average age was 34.9 years (range, 19–61 years). The distribution of body mass index (BMI) was comparable between healthy volunteers and patients with constipation: the mean BMI of healthy volunteers was 22.15 kg/m<sup>2</sup>  (range, 19–26.3 kg/m<sup>2</sup> ) and 23.45 kg/m<sup>2</sup>  (range, 19.1–29.4 kg/m<sup>2</sup> ) for patients with constipation ([[#tbl1|Table 1]] ).

<span id='tbl1'></span>

{| class="wikitable" style="min-width: 60%;margin-left: auto; margin-right: auto;"
|+

Table 1.

Anorectal manometric parameters among 14 Taiwanese patients.

|-

! colspan="5" | Demographic characters
! colspan="9" | Anorectal manometry
|-

! No.
! Age (y)
! Sex
! BMI (kg/m<sup>2</sup> )                                                    
! Groups
! Resting pressure 36.8–72.5 mmHg                                                    
! Squeeze pressure 33–202.3 mmHg                                                    
! Max squeeze pressure 90–249.3 mmHg                                                    
! Anal length 1–3 cm                                                    
! RAIR 10–30 cm<sup>3</sup>
! First sensation 10–75 cm<sup>3</sup>
! Urge 60–200 cm<sup>3</sup>
! Max tolerant 135–320 cm<sup>3</sup>
! Compliance 3.5–12.2 mmHg
|-

| 1
| 19
| F
| 19.1
| C
| 50.7
| 166.75
| 217.5
| 2
| 20
| 50
| 130
| 170
| 18.1
|-

| 2
| 30
| F
| 22.6
| C
| 30.8
| 96.45
| 127
| 2
| 30
| 100
| 150
| 250
| 2.7
|-

| 3
| 25
| F
| 20.2
| C
| 26.65
| 1.5
| 20.9
| 2
| 30
| 50
| 100
| 230
| 3
|-

| 4
| 21
| F
| 25.8
| C
| 45.95
| 76.15
| 122.1
| 2
| 20
| 50
| 100
| 140
| 53.6
|-

| 5
| 29
| F
| 21.5
| C
| 18.85
| 76.45
| 79.1
| 2
| 20
| 50
| 100
| 130
| 4.6
|-

| 6
| 61
| M
| 20.6
| C
| 12.1
| 165.5
| 171.2
| 4
| 20
| 50
| 80
| 100
| 1.2
|-

| 7
| 33
| F
| 29.4
| C
| 22.25
| 63.25
| 83.1
| 1
| 20
| 50
| 160
| 190
| 4
|-

| 8
| 61
| F
| 28.4
| C
| 22.2
| 76.9
| 86.5
| 3
| 20
| 50
| 100
| 200
| 11.6
|-

| 12
| 48
| F
| 19.4
| N
| 26.35
| 32.3
| 48.8
| 1
| 20
| 50
| 100
| 140
| 8.1
|-

| 13
| 23
| M
| 20.2
| N
| 26.1
| 173.85
| 199.7
| 2
| 20
| 50
| 150
| 200
| 5.7
|-

| 14
| 22
| M
| 19
| N
| 49.5
| 290.9
| 340.2
| 1
| 20
| 50
| 100
| 130
| 10.7
|-

| 15
| 20
| F
| 26.3
| N
| 61.35
| 32.15
| 83.2
| 3
| 20
| 50
| 90
| 130
| 7.6
|-

| 16
| 24
| M
| 24.5
| N
| 69.45
| 52.35
| 117.3
| 3
| 30
| 50
| 140
| 220
| 5.3
|-

| 17
| 25
| M
| 23.5
| N
| 59.65
| 223.3
| 283
| 2
| 10
| 100
| 150
| 200
| 4.2
|}

BMI = body mass index; C = patients with chronic constipation; N = healthy volunteers; RAIR = rectoanal inhibitory reflex.

===Anorectal manometry in the study population===

Patients with chronic constipation and healthy volunteers had similar mean anal length, threshold for eliciting rectoanal inhibitory reflexes, and threshold volumes for the first sensation. However, compared to healthy volunteers, patients with chronic constipation had lower threshold for mean resting pressure [constipation vs. healthy mean ± standard deviation (SD) 28.7 ± 13.3 mmHg vs. 48.7 ± 18.5 mmHg, ''p''  = 0.052), lower squeeze pressure (90.4 ± 54.4 mmHg vs. 134.1 ± 111.0 mmHg), lower maximal squeeze pressure (105.2 ± 67.3 mmHg vs. 178.7 ± 115.9 mmHg), lower threshold volumes for urge (115 ± 28.3 cm<sup>3</sup>  vs. 121.7 ± 27.9 cm<sup>3</sup> ), but higher threshold pressures for compliance (12.4 ± 17.6 mmHg vs. 6.9 ± 2.4 mmHg; [[#tbl2|Table 2]] ). Because this study was limited in its small sample size, the differences between constipation patients and healthy volunteers were not statistically significant.

<span id='tbl2'></span>

{| class="wikitable" style="min-width: 60%;margin-left: auto; margin-right: auto;"
|+

Table 2.

Anorectal manometric parameters and successful rectal balloon expulsion test between patients with constipation and controls.

|-

! rowspan="2" | Groups
! colspan="9" | Anorectal manometry
|-

! Resting pressure 36.8–72.5 mmHg                                                    
! Squeeze pressure 33–202.3 mmHg                                                    
! Max squeeze pressure 90–249.3 mmHg                                                    
! Anal length 1–3 cm                                                    
! RAIR 10–30 cm<sup>3</sup>
! First sensation 10–75 cm<sup>3</sup>
! Urge 60–200 cm<sup>3</sup>
! Max tolerant 135–320 cm<sup>3</sup>
! Compliance 3.5–12.2 mmHg
|-

! colspan="10" | All participants
|-

|  Success[[#tbl2fna|<sup>a</sup>]] , ''n''  = 6                                                    
| 27.3
| 139.2
| 161.0
| 2.0
| 21.7
| 58.3
| 113.3
| 158.3
| 5.5
|-

|  Failure[[#tbl2fnb|<sup>b</sup>]] , ''n''  = 8                                                    
| 44.8
| 86.5
| 126.7
| 2.3
| 21.3
| 56.3
| 121.3
| 185.0
| 13.4
|-

| Patients with chronic constipation, ''n''  = 8                                                    
| 28.7*
| 90.4
| 113.4
| 2.3
| 22.5
| 56.3
| 115.0
| 176.3
| 12.4
|-

|  Success, ''n''  = 3                                                    
| 20.6
| 112.8
| 125.8
| 2.7
| 23.3
| 66.7
| 110.0
| 160.0
| 2.8
|-

|  Failure, ''n''  = 5                                                    
| 33.6
| 76.9
| 106.0
| 2.0
| 22.0
| 50.0
| 118.0
| 186.0
| 18.1
|-

| Healthy volunteers, ''n''  = 6                                                    
| 48.7*
| 134.1
| 178.7
| 2.0
| 20.0
| 58.3
| 121.7
| 170.0
| 6.9
|-

|  Success, ''n''  = 3                                                    
| 63.5
| 102.6
| 161.2
| 2.7
| 20.0
| 66.7
| 126.7
| 183.3
| 5.7
|-

|  Failure, ''n''  = 3                                                    
| 37.8
| 232.4
| 270.0
| 1.5
| 20.0
| 50.0
| 125.0
| 165.0
| 8.2
|}

*Difference between patients with chronic constipation and healthy volunteers had marginal significance (''p''  = 0.052).                      

RAIR = rectoanal inhibitory reflex.

a. Success indicates successful balloon expulsion.

b. Failure to expel the rectal balloon.

===BE test in the study population===

Among participants who had successful BE in one of three different positions, three patients had constipation (3/8, 37.5%), and three were healthy volunteers (3/6, 50%; [[#tbl3|Table 3]] ). One patient with constipation had successful BE in the left lateral decubitus position, and two had successful BE in a squat position. By contrast, one healthy volunteer had successful BE in the sitting position, and two had successful BE only in the squat position ([[#tbl4|Table 4]] ).

<span id='tbl3'></span>

{| class="wikitable" style="min-width: 60%;margin-left: auto; margin-right: auto;"
|+

Table 3.

Successful rectal BE test rate among different body positions.[[#tbl3fna|<sup>a</sup>]]

|-

! rowspan="2" | Groups
! colspan="3" | BE test among different body positions, ''n''  (%)
|-

! Left lateral decubitus
! Sitting
! Squat
|-

! colspan="4" | Patients with chronic constipation,
|-

|  ''n''  = 8                                                    
| 1 (12.5)
| 0
| 2 (25.0)
|-

! colspan="4" | Healthy volunteers
|-

|  ''n''  = 6                                                    
| 0
| 1 (16.7)
| 2 (33.3)
|}

BE = balloon expulsion.

<span id='tbl3fna'></span>

a. If patients had successful BE in the former position, their results in the latter position were not evaluated. For example, if one patient had successful BE in left lateral decubitus position, his/or her BE in sitting and squat positions were labeled as success.

<span id='tbl4'></span>

{| class="wikitable" style="min-width: 60%;margin-left: auto; margin-right: auto;"
|+

Table 4.

Rectal BE and discomfort location among 14 Taiwanese patients.

|-

! colspan="2" | Study participants
! colspan="3" | BE test and discomfort location
|-

! rowspan="2" | No.
! rowspan="2" | Groups
! colspan="3" | Position
|-

! Left lateral decubitus position
! Sitting position
! Squat position
|-

| 1
| C
| Failure[[#tbl4fna|<sup>a</sup>]]
| Failure
| Failure
|-

| 2
| C
| Success[[#tbl4fnb|<sup>b</sup>]]
| —
| —
|-

| 3
| C
| Failure
| Failure
| Failure
|-

| 4
| C
| Failure
| Failure
| Failure
|-

| 5
| C
| Failure
| Failure
| Success
|-

| 6
| C
| Failure
| Failure
| Success
|-

| 7
| C
| Failure
| Failure
| Failure
|-

| 8
| C
| Failure
| Failure
| Failure
|-

| 12
| N
| Failure
| Success
| —
|-

| 13
| N
| Failure
| Failure
| Success
|-

| 14
| N
| Failure
| Failure
| Success
|-

| 15
| N
| Failure
| Failure
| Failure
|-

| 16
| N
| Failure
| Failure
| Failure
|-

| 17
| N
| Failure
| Failure
| Failure
|}

C = patients with chronic constipation; N = healthy volunteers.

a. Failure to expel rectal balloon.

b. Success indicates successful balloon expulsion.

===Relationship between anorectal manometry and BE===

Patients with successful BE in one position and patients with failed BE in all three positions had similar mean rectal sensory thresholds for the first sensation (successful BE vs. failed BE: 58.3 cm<sup>3</sup>  vs. 56.3 cm<sup>3</sup> ). However, patients with successful BE in one position seemed to have lower mean resting pressure (227.0 mmHg vs. 44.8 mmHg, ''p''  = 0.061), lower mean threshold volumes for urge (successful BE vs. failed BE: 113.3 cm<sup>3</sup>  vs. 121.3 cm<sup>3</sup> ), lower mean threshold pressures for compliance (5.5 mmHg vs. 13.4 mmHg), and higher mean maximal squeeze pressure (successful BE vs. failed BE: 161 mmHg vs. 126.7 mmHg) than patients with failed BE in all three positions had ([[#tbl4|Table 4]] ). As this study was limited in its small sample size, the relationship between anorectal manometry and BE was not statistically significant.      

==Discussion==

In this study, we examined eight Taiwanese patients with chronic constipation and six healthy volunteers by solid-state anorectal manometry and BE, and found that patients with chronic constipation had a trend of lower successful rate of rectal BE than that of healthy controls. Moreover, we also demonstrated an agreement between BE and anorectal manometry in Taiwanese individuals. Although this study was limited in its small sample size, the primitive results implied the feasibility of BE for the evaluation of constipation in Taiwanese patients.

BE is a simple screening test, and the failure to expel a balloon usually suggests a strong possibility of PFD [[#bib11|[11]]] . Although BE has been shown to have a sensitivity of 88%, a specificity of 89%, a positive predictive value of 67%, and a negative predictive value of 97% for excluding PFD [[#bib3|[3]]] , one team reported that patients with PFD could expel the balloon [[#bib12|[12]]] , and 0–16% of healthy controls had difficulty in evacuating the balloon [[#bib11|[11]]] , which means that BE is insufficient to make a diagnosis of a defecatory disorder and a normal test could not exclude the possibility of a defecatory disorder [[#bib13|[13]]] . Moreover, BE cannot define the structural abnormality of anorectum and mechanisms of disordered defecation [[#bib8|[8]]] . Of note, our previous study using conventional anorectal manometric techniques showed a distinctive abnormality of anal sphincter function in Taiwanese patients with chronic constipation, and suggested that the clinical utility of anorectal manometric techniques to identify individuals with various abnormal rectal subtypes in chronic constipation [[#bib6|[6]]] .      

Therefore, although BE may be useful for the evaluation of constipation in Taiwanese patients, an integration of BE with other anorectal physiological tests, such as anorectal manometry, might be more informative in the evaluation of PFD [[#bib8|[8]]] .      

Previous studies have demonstrated a limited concurrence between anorectal manometry and BE for identifying PFD [[#bib14|[14]]] ; [[#bib15|[15]]]  ;  [[#bib16|[16]]] . In this study, although we found that the rectal sensory threshold for the first sensation was compatible with BE, patients with success in one position had lower mean threshold volumes for urge, lower mean threshold pressures for compliance, and higher mean maximal squeeze pressure than patients with failed BE in all three positions had. However, because the study sample size was small, our data only demonstrated the agreement between anorectal manometry and BE, whether measurements of anorectal manometry and BE are concurrent for identifying PFD in Taiwanese patients remain unclear. Future larger studies are needed to clarify these important issues.      

We evaluated BE in the left lateral decubitus position for all the study participants and then in the sitting and squat position only in those who could not expel a balloon in the left lateral position. Therefore, BE was not evaluated in all positions for all participants, and the assessment of concordance among different positions was incomplete. Moreover, because the number of this study is limited and small due to difficulty in enrolling the patients, and the differences in demographic characters, such as age and gender, between groups are statistically significant, results of this study need more cautious interpretation in terms of these different characters and type I errors.

In conclusion, this work demonstrated that failure of BE appears to occur in patients with chronic constipation as well as some healthy adults. Moreover, the results of BE are in agreement with those of anorectal manometry in Taiwanese individuals. Although the utility of BE for differentiating patients with constipation and healthy controls remains to be determined, the results confirm the feasibility of BE along with anorectal manometry in clinical practice. However, since idiopathic constipation is a condition with complex pathophysiology, future, larger studies are needed to fully examine the role of BE in differentiating constipation in term of PFD.

==Conflicts of interest==

All authors declare no conflicts of interest.

==Acknowledgments==

We thank all of those who helped to enroll and follow up the study participants. We are also grateful to the research assistants who assisted in laboratory analyses and collected clinical information. Finally, we would like to thank the anonymous reviewers and the editor for their constructive comments. This work was supported by grants from the Hualien Tzu Chi Hospital  and Taipei Tzu Chi Hospital , Buddhist Tzu Chi Medical Foundation  ([[#gs3|TCRD-TPE-103-35]] , [[#gs3|TCRD-TPE-104-31]] , [[#gs3|TCMMP104-02-02]] , and [[#gs3|TCMMP104-02-01]] ).

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