Routine enema before urodynamics has no impact on the quality of abdominal pressure curves: Results of a prospective controlled study

25 décembre 2016

Auteurs : H. Rigole, N. Senal, M. Damphousse, C. Brochard, A. Manunta, J. Kerdraon, L. Tondut, Q. Alimi, J. Hascoet, L. Siproudhis, B. Peyronnet, I. Bonan
Référence : Prog Urol, 2016, 17, 26, 1200-1205



Urodynamics is the reference method for defining the pathophysiology of lower urinary tract dysfunction [1, 2, 3]. During filling cystometry, a catheter is inserted in the bladder for continuous measurement of bladder pressure. As the bladder is within the abdominal cavity, it is advisable to measure intra-abdominal pressure (AP) so as to establish whether increase in bladder pressure is due to an increase in abdominal pressure or to detrusor contraction [4]. A rectal catheter is used to determine the AP curve, the quality of which is essential in interpreting the urodynamic testing [5]. This measurement in theory requires an empty rectum as the degree of rectal distension can affect the sensitivity and contractility of the bladder and hence the result of the exam [6, 7].

However, constipation is frequent in the general population and even more so in neurological patients [8, 9, 10, 11, 12]. The presence of stools in the rectum may hinder measurement of AP and results in artifacts that hamper or even prevent interpretation of the exam. Sodium phosphate enema (SPE) is a common and simple method used to achieve bowel evacuation, which is recommended as a routine procedure before anorectal manometry [13]. However, the effect of routine SPE before filling cystometry on the quality of the AP curve has never been assessed, and this was therefore the aim of our study.

Material and methods

Patients and study methodology

A prospective, non-randomized, controlled single-blind study was conducted in a single center after approval by the local ethics committee. The patient inclusion criteria were as follows: patients age 18 years or over referred for urodynamic tests between May and June 2013. The only exclusion criterion was refusal by the patient to participate in the study. All eligible subjects received a standardized notification to attend that included administrative details, a prescription for urine culture, and information on the urodynamic test procedure.

The patients were divided into two groups: patients who underwent urodynamic testing during the first 6 weeks and were not given a prescription for SPE to be done before testing (group A); patients who underwent urodynamic testing during the second 6 weeks (group B) and were given a prescription for SPE and a document asking them to have an SPE either the evening before for a morning test or in the morning for an afternoon test.

Prior to testing, the usual data were collected from each patient, notably the presence of any neurological disorder, age, sex, and, for group B patients, whether or not they had had the prescribed SPE, and if not why.

At the end of the study, the pressure curves were collected, anonymized, and ordered alphabetically so as to mix groups A and B and ensure that the three physicians who interpreted the data were blinded to the study group. The curves were then examined separately by the three physicians (two physical therapists and one urologist), all of whom were experienced in urodynamics.

The primary endpoint was the quality of the AP curves, scored independently by the three physicians as follows:

perfectly interpretable (PI): equal pressure variation in the two curves for bladder pressure and AP during the cough test repeated every minute during filling, with a tolerance of 10cm H2 O and no artifact in the AP curve;
interpretable but artifactual (IA): good transmission of pressure during the cough test, but artifacts in the curve;
uninterpretable (UI): poor transmission of pressure during the cough test and artifacts in the curve.

If the 3 interpretations were different, the curve was excluded from the analysis of the quality of the AP curve (n =2).

The secondary endpoints were the degree of difficulty of the preparation for urodynamics, assessed using a Likert scale (0: maximum simplicity, 10: insuperable difficulty) and the overall bother of testing assessed by the patient using a Likert scale (0: not bothersome, 10: intolerable).


Urodynamic evaluation was done according to the recommendations of the International Continence Society [14]. Patients were assigned to two different machines, machine α from Laborie® using I-LIST software and a T-DOC air-charged aerodynamic catheter, and machine β from Dantec® using DUET software and an air-filled balloon catheter.

Statistical analyses

Statistical analyses were done using JMP v.12.0® software (SAS Institute Inc, Cary, NC, US). The parameters of the 2 groups were compared using Fisher's test or the &khgr;2 test for qualitative variables and the Mann-Whitney test for quantitative continuous variables. An intent-to-treat (comparison of groups A and B, whether or not the patients of group B underwent the prescribed SPE) and a per protocol analyzes were performed (by comparing the group of patients who had an SPE with the group of patients who had no SPE). Univariate analysis was used to assess the association of the quality of the AP measurements with the type of urodynamic device, the patient's age, and the presence or otherwise of a neurological disorder.


Patient characteristics

A total of 139 patients underwent urodynamic evaluation: 54 in group A (15 men, 27.8%) and 85 in group B (19 men, 22.3%; P =0.47). Their mean age was 56.7 years in group A and 54.8 years in group B (P =0.78). The proportion of patients with a neurological disorder was similar in the two groups, respectively (30% vs. 33%; P =0.68).

Among the patients of group B, 14 (16%) did not have an SPE, 5 of whom were not neurological patients (9% of such patients) and 9 neurological patients (32% of such patients), the difference being statistically significant (P =0.01). The reasons for not performing an SPE were as follows:

neurological patients: 2 had already undergone transanal irrigation; 1 was already using daily an effervescent suppository for bowel evacuation; 2 were dependent on a nurse for the procedure; 4 refused to do an SPE;
non-neurological patients: 1 had recent hemorrhoid surgery; 1 had a colostomy; 3 refused to do an SPE.

There was no difference in sex between the patients who did or did not undergo SPE in group B, but there were fewer neurological patients among those who underwent an SPE (P =0.01), and the patients who underwent an SPE were significantly (P =0.02) older (mean age 56.8 years) than those who did not (mean age 44.6). No complication related to SPE was noted.

Intent-to-treat analysis

There was no significant difference between groups in terms of bother of the exam (3.51 vs. 3.11; P =0.41) or the difficulty of preparing for it (3.35 vs. 3.02; P =0.55) (Table 1). The quality of the AP curve was similar in the two groups, with 67% of the AP curves deemed perfectly interpretable in the two groups (P =0.99).

Per protocol analysis

Comparison of the 71 patients who had an SPE and the 68 who did not showed that there was no significant difference in terms of the bother of the exam (Likert scale score: 3.46 vs. 2.97; P =0.43) or difficulty in preparing for it (Likert scale score: 3.12 vs. 3.18; P =0.91) (Table 2). The AP curve was considered fully interpretable (PI) in 69% of the patients who had no SPE and in 65% of the patients who had an SPE (P =0.61).

Factors associated with the interpretability of the abdominal pressure curve

Among the patients who had no SPE, those aged 60 or over had AP curves deemed 61% PI/29% IA/10% UI; the corresponding figures for the under-60s were 75% PI/11% IA/8% UI. The difference was significant (P =0.001). There was no significant difference in terms of bother of the exam, the difficulty of preparation for the exam, or the quality of the AP curves between those aged 60 or over and the under-60s, regardless of whether or not they had an SPE.

The presence of a neurological disorder had no impact on the quality of the AP curves, regardless of whether the patients had an SPE (PI: 68% vs. 66%; P =0.76) or not (PI: 68% vs. 70%; P =0.93). Detrusor overactivity had no impact on the quality of the AP curves (PI: 65% vs. 69%; P =0.57).

In contrast, the type of urodynamic device used had an impact on the quality of the AP curves, whether the patients had an SPE (Dantec® vs. Laborie®: PI: 79% vs. 43%; P =0.01) or not (Dantec® vs. Laborie®: PI: 82% vs. 44%; P =0.01).


The question of the quality of intestinal transit and bowel emptying is unavoidable in urology, as it may influence the sensitivity and contractility of the bladder through visceral reflexes [6, 7]. Colonic irrigation with water before an urodynamic evaluation in patients with spina bifida had no impact on the interpretability of filling cystometry [15]. However, the presence of stools in the rectal ampulla is a daily preoccupation for those performing urodynamic evaluations because it can hamper the measurement of rectal pressure and affect the quality of the AP curve. Gastroenterologists therefore routinely prescribe bowel emptying by two successive SPE a few hours before any anorectal manometry [13]. The guidelines consider that continuous monitoring of rectal pressure during filling cystometry is a criterion of interpretability [1]. We therefore hypothesized that routine SPE before urodynamic evaluation may be of value in improving the quality of AP curves.

Although rare, fluid and electrolyte balance complications of SPE (some lethal) have been reported in frail patients with multiple comorbidities [16]. It is essential to demonstrate the value of SPE before recommending its routine use. In our study, routine SPE before urodynamic evaluation was accepted by the vast majority of patients, and was well tolerated insofar as the exam did not seem complicated and was not deemed bothersome by the patients who underwent it. No SPE-related complication was noted.

Constipation is more prevalent among older subjects. In our study, advanced age was associated with a significantly higher rate of SPE. This difference may perhaps be explained by a cultural difference in how SPE is experienced by older patients, despite a dependency that one may suppose increases with age. A greater effect of SPE on the quality of AP curves may be anticipated in those aged 60 or over and in neurological patients, in whom the rate of constipation is reckoned to be higher than in younger or non-neurological patients. There was no significant difference in the quality of the AP curves between patients aged 60 or over and the under-60s, whether or not they had an SPE, or between neurological and non-neurological patients.

The main finding of our study is that, in contrast to our initial hypothesis, routine SPE before a urodynamic evaluation does not improve quality or interpretability of AP curves. One explanation may be that, unlike gastroenterologists before manometry, we prescribed a single SPE before the exam (versus two SPE before anorectal manometry: the day before and the morning of the exam). Unlike transanal irrigation, SPE more or less empties the rectum and sigmoid colon, but not the left colon [17]. The decision to prescribe a single SPE was taken for reasons of reliability, as the proportion of potentially dependent neurological patients among our study participants and the unusual nature of this procedure raised the fear that if we prescribed two SPE the rate of adherence would be lower. This choice is a limitation of our study.

In the literature, a single publication has analyzed potential artifacts in filling cystometry and possible remedial action [18]. Reported artifacts in AP are attributed to shocks applied to the catheter, vibrations transmitted by contact with the catheter, rectal overactivity, and a transient drop in AP of about 10 cmH2 O in the event of a leak or miction [18]. The role of the presence of stools was not considered, but the rectal pressure catheter used in this study was a T-DOC air-charged aerodynamic catheter, which is theoretically protected against stools. Inasmuch as machine β used air-filled balloon catheters, which may have afforded protection against stools, and machine α used T-DOC air-charged aerodynamic catheters, it is possible, albeit not demonstrated, that these catheters are less sensitive to the presence of stools, as they cannot be blocked. This hypothesis may explain our observed lack of influence of prior SPE on the quality of the AP curve in filling cystometry.

Our study has several other limitations. First, despite the prospective design, the allocation to the SPE or no SPA arms depended on the period of evaluation, which cannot be considered a strict randomization. Another limitation is that there was no check that the SPE was in fact performed; nor was it checked by digital rectal examination that the rectum was empty before the exam, as the SPE may have been ineffective in some cases. The high prevalence of intestinal motility disorders in neurological patients means that this population is particularly suited to our procedure, which is, however, difficult to put in place because of the dependence of these patients. Personalized preparation would therefore have been necessary to ensure the quality of bowel emptying before assessment in this population, which is a limitation of our methodology. A new study with verification by digital rectal examination that the rectum is empty at the start of the urodynamic evaluation would be necessary to draw more formal conclusions. Lastly, the negative result of our study should be interpreted with caution as the number of subjects needed was not calculated and the relatively small number of participants could be associated with a lack of statistical power, the non-significant difference not being considered an equivalence in this context.


In our prospective controlled study, routine SPE did not increase the bother of the urodynamic evaluation or the difficulty of preparation for the evaluation, according to the patients, but it also did not have an impact on the quality of the AP curves. Based on our findings, we cannot therefore recommend the routine use of an SPE before urodynamic evaluation.

Disclosure of interest

The authors declare that they have no competing interest.


This article was translated with the support of LABORIE©.

Appendix A. Supplementary data

(121 Ko)

Table 1 - Intent-to-treat analysis.
  Group A (n =54)
No prescription of SPE before urodynamic evaluation 
Group B (n =85)
Prescription of SPE before urodynamic evaluation 
P value 
Sex  15 men/39 women  19 men/66 women  0.47 
Mean age (years)  56.7  54.8  0.78 
Neurological disorder  No: 38/yes: 16 (30%)  No: 57/yes: 28 (33%)  0.68 
Urodynamic device used  α: 19/β: 35  α: 30/β: 55  0.99 
Mean score (Likert scale) for complicated nature of preparation for the urodynamic evaluation  3.35  3.02  0.55 
Mean score (Likert scale) for the bother of the urodynamic evaluation  3.51  3.11  0.41 
Quality of the abdominal pressure curve  PI: 36 (67%)/IA: 11 (20%)/UI: 6 (11%)/?a: 1  PI: 57 (67%)/IA: 17 (20%)/UI: 10 (12%)/?a: 1  0.99 

Légende :
PI: perfectly interpretable; IA: interpretable but artifactual; UI: uninterpretable; α: Laborie® system; β: Dantec® system; SPE: sodium phosphate enema.

Curve excluded, 3 different responses.

Table 2 - Per protocol analysis.
  SPE not done (n =68)  SPE done (n =71)  P value 
Sex  17 men/51 women  17 men/54 women  0.88 
Mean age (years)  54.2  56.8  0.71 
Neurological disorder  n =25  n =19  0.20 
Urodynamic device used  3.12  3.18  0.91 
Mean score (Likert scale) for complicated nature of preparation for the urodynamic evaluation  3.46  2.97  0.43 
Mean score (Likert scale) for the bother of the urodynamic evaluation  PI: 47 (69%)/IA: 13 (19%)/UI: 6 (9%)/?a: 2  PI: 46 (65%)/IA: 15 (21%)/UI: 10 (14%)/?a: 0  0.61 

Légende :
PI: perfectly interpretable; IA: interpretable but artifactual; UI: uninterpretable; α: Laborie® system; β: Dantec® system; SPE: sodium phosphate enema.

Curve excluded, 3 different responses.


Syan R., Brucker B.M. Guideline of guidelines: urinary incontinence BJU Int 2016 ;  117 (1) : 20-33 [cross-ref]
Hermieu J.F., Denys P., Fritel X. Critical review of guidelines for female urinary incontinence diagnosis and treatment Prog Urol 2012 ;  22 (11) : 636-643 [inter-ref]
Peyronnet B., Rigole H., Damphousse M., Manunta A. Management of overactive bladder in women Prog Urol 2015 ;  25 (14) : 877-883 [inter-ref]
Schäfer W., Abrams P., Liao L., Mattiasson A., Pesce F., Spangberg A., et al. Good urodynamic practices uroflowmetry, filling cystometry, and pressure-flow studies Neurourol Urodyn 2002 ;  21 : 261-274
Gammie A., Clarkson B., Constantinou C., Damaser M., Drinnan M., Geleijnse G., et al. International Continence Society guidelines on urodynamic equipment performance Neurourol Urodyn 2014 ;  33 (4) : 370-379 [cross-ref]
De Wachter S., Wyndaele J.J. Impact of rectal distention on the results of evaluations of lower urinary tract sensation J Urol 2003 ;  169 (4) : 1392-1394 [cross-ref]
Noronha R., Akbarali H., Malykhina A., Foreman R.D., Greenwood-Van Meerveld B. Changes in urinary bladder smooth muscle function in response to colonic inflammation Am J Physiol Renal Physiol 2007 ;  293 (5) : F1461-F1467
Higgins P.D., Johanson J.F. Epidemiology of constipation in North America: a systematic review Am J Gastroenterol 2004 ;  99 (4) : 750-759 [cross-ref]
Hinds J.P., Eidelman B.H., Wald A. Prevalence of bowel dysfunction in multiple sclerosis. A population survey Gastroenterology 1990 ;  98 (6) : 1538-1542 [cross-ref]
Soler J.M., Denys P., Game X., Ruffion A., Chartier-Kastler E. Anal incontinence and gastrointestinal disorders and their treatment in neurourology Prog Urol 2007 ;  17 (3) : 622-628 [cross-ref]
Vallès M., Vidal J., Clavé P., Mearin F. Bowel dysfunction in patients with motor complete spinal cord injury: clinical, neurological, pathophysiological associations Am J Gastroenterol 2006 ;  101 (10) : 2290-2299
Wyndaele M., De Winter B.Y., Pelckmans P., Wyndaele J.J. Lower bowel function in urinary incontinent women, urinary continent women and in controls Neurourol Urodyn 2011 ;  30 : 138-143 [cross-ref]
Leroi A.M. Les explorations fonctionnelles digestives  : Elsevier Masson (2010). 131-143
Abrams P., Andersson K.E., Birder L., et al. Recommendations of the International Scientific Committee: evaluation and treatment of urinary incontinence  Pelvic Organ Prolapse and Faecal Incontinence :  (2009). 
De Kort L.M., Nesselaar C.H., Van Gool J.D., De Jong T.P. The influence of colonic enema irrigation on urodynamics findings in patients with neurogenic bladder dysfunction Br J Urol 1997 ;  80 (5) : 731-733
Mendoza J., Legido J., Rubio S., Gisbert J.P. Systematic review: the adverse effects of sodium phosphate enema Aliment Pharmacol Ther 2007 ;  26 (1) : 9-20 [cross-ref]
Fourtassi M., Charvier K., Hajjioui A., Havé L., Rode G. Transanal irrigation for bowel and anorectal management in spinal cord-injured patients Prog Urol 2012 ;  22 (8) : 467-474 [inter-ref]
Hogan S., Gammie A., Abrams P. Urodynamic features and artefacts Neurourol Urodyn 2012 ;  31 (7) : 1104-1117 [cross-ref]

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