Age effect

ORIGINAL ARTICLE

Age effects on anorectal pressure in anal continent women with lower urinary tract dysfunction

Soo-Cheen Ng&Gin-Den Chen

Received:10November2005/Accepted:13May2006/Published online:22June2006

#International Urogynecology Journal2006

Abstract The objective of this paper is to evaluate age and associated factors affecting anorectal pressure profilometry in anal-continent women with lower urinary tract symp-toms.One hundred and ten anal-continent women(mean age,47.7±12.8years;range,23–87years)with lower urinary tract symptoms voluntarily participated in this study after undergoing a complete urogynecological evaluation including a multichannel urodynamic study.Anorectal pressure was evaluated by using a radial four-channel manometry with a water-filled catheter,which was placed 10cm into the anorectum above the anal verge.We divided the anorectal pressure profile into five segments and four axes to clarify the axis-specific defect or site-specific damage in the sphincter profile.The aging process had a negative effect on the peak resting pressure from the41to 100th percentile of the anorectal pressure profile at12 o’clock,3o’clock,and6o’clock(P<0.05).With voluntary squeezing,aging had negative effects on the peak squeeze pressure from the41to100th percentile of the anorectal pressure profile at3o’clock,and61to80percentile at12 o’clock(P<0.05).There is a trend where anorectal pressure reduces as a woman ages,especially at the anal sphincter area in women with lower urinary tract symptoms.The anterior and left sides of the anorectal sphincter seem to be the most vulnerable in the aging process.

Keywords Manometry.Anal rectal function.Age.

Lower urinary tract symptoms.Rectocele Introduction

Anorectal canal pressure,measured by anal manometry,is widely used to quantify internal and external anal sphincter function.The internal sphincter component contributes most to the resting tone of the anorectal canal.During voluntary anal contraction,the external sphincter muscle,the pubor-ectalis,and the levator ani muscles contribute to the additional squeeze pressure[1].In the past two decades,several studies have used manometry examinations to evaluate the effect of various factors such as age,parity,and gender difference on anal function or anorectal pressure in healthy women[2–5]. However,the results regarding the changes in anorectal pressure were inconsistent among these studies.

In patients suffering from fecal incontinence after delivery,anal canal pressure at rest or during squeezing is often lower than that of patients without fecal incontinence [5–7].The clinical utility of anal manometry in patients with anorectal dysfunction has not yet been well-defined because there is an enormous overlap for determining manometric abnormalities and there are no clear-cut criteria [8].The anal canal pressure may not perfectly correlate with incontinence because of the wide range of normal pressures.In addition,there are many factors such as abnormal rectal capacity or compliance,anal sensitivity, consistency of the stools,or idiopathic fecal incontinence, which may cause fecal incontinence in the absence of a decrease in anal canal pressure[7,8].

In past decades,some studies have demonstrated that the prevalence of anal incontinence(fecal and/or flatus inconti-nence)increases among women with urinary incontinence or urogynecological complaints[9–11].These studies suggest that women with lower urinary tract symptoms or disorders might share some potential risk factors such as the effects of

Int Urogynecol J(2007)18:295–300

DOI10.1007/s00192-006-0155-1

S.-C.Ng

:G.-D.Chen(*)

Department of Obstetrics and Gynecology, Chung Shan Medical University Hospital, 110,Section1,Chien-Kou N.Road, Taichung,40203Taiwan,Republic of China e-mail:gdchen@https://www.wendangku.net/doc/cf10866411.html,

hypoestrogenization,genetics,concomitant damage,and dual innervations that would predispose them to the occurrence of anorectal dysfunctions.The cumulative inci-dences of urinary incontinence or overactive bladder also gradually increase with increasing age[12].To the best of our knowledge,no known studies has been conducted to evaluate the change of anorectal pressure in women suffering from lower urinary tract symptoms.We do not know whether changes of anorectal pressure in anal-continent women with lower urinary tract dysfunction are similar to those of normal women or in women having anal incontinence.

In this study,we try to evaluate whether variables such as uterovaginal prolapse,vaginal delivery,age,and menopause,which have been shown to predispose women to the occurrence of urinary incontinence,also affect anorectal function or not.We also try to evaluate the site-specific defect demonstrated by the changes in anorectal pressure.

Materials and methods

From March1999to December2002,women with lower urinary tract symptoms,who were referred to the urogynecol-ogy unit of Chung Shan Medical University Hospital were invited to participate in this study.After a full explanation of the procedure,informed consent was obtained from each woman who agreed to receive an anorectal manometry examination.None of the women who were included in this study had symptoms of anal incontinence(fecal incontinence and/or flatus incontinence).Patients with preexisting diabetes mellitus,neurological disorders,cognitive disorders,previous anti-incontinence or anorectal surgery,obstructive defecation, constipation,radiation,and chronic pelvic pain were all excluded from this study.The Chung Shan Institutional Review Board,Taichung,Taiwan,approved the study protocol.

A total of110women voluntarily received an anorectal manometry test after the urodynamic https://www.wendangku.net/doc/cf10866411.html,rmation regarding various lower urinary tract symptoms,medical, gynecological,and obstetric histories was obtained.All patients underwent a complete urogynecologic evaluation including a physical examination,urine analysis,pad test for quantification of urine leakage,and a multichannel urody-namic study.Pelvic examinations were performed in the lithotomy position and standing position by the same doctor (G.D.C.)after the patient had emptied her bladder.First,the doctor pressed downward on the perineum and asked the patients to bear down with maximal effort.A Sim's retractor was subsequently inserted vaginally.The patient was asked to perform Valsalva abdominal straining and cough during the examination to confirm the full extent of the uterovagi-nal prolapse.The severity of the pelvic organ prolapse was defined according to the classification system approved by the International Continence Society in1996(POP-Q system)[13].Patients with uterovaginal prolapse greater than stage II were excluded from this study in an attempt to control the possible outlier effect.

After the urodynamic study,all of the patients were assessed in the left lateral position with the thigh and knee flexed.The manometric pump system(Mui Scientific, Mississauga,Ontario,Canada)consists of a radially distributed four-channel,continuously perfused catheter (infusion rate0.5ml/min of distilled water)and a low-compliance pressure transducer connected to a polygraph (DUET,Medtronic Dantec,Denmark).All four channels of the pressure catheter were situated at the same cross-section along the catheter and separated by90°.The catheter was placed10cm into the anorectum above the anal verge.A continuous pull-through technique(Uro Primer,Medtronic Dantec)was used to withdraw the anal pressure catheter at a constant speed of2mm/s to yield a smooth and reproducible pressure profile.After the first set of resting anal pressure results,the maximal squeeze pressure was determined by the same continuous pull-through technique with the patients instructed to maxi-mally squeeze their anal sphincter and to maintain this for as long as possible.Data of anorectal pressure profilo-metry from each patient were subsequently processed and analyzed by a computer system(Pentium II Software Polygram,DUET,Medtronic Dantec).

An overall maximum resting pressure of the anorectal canal was identified as the maximum increase of the pressure curve during pull-through when the patient relaxed.Subse-quently,the patient was asked to squeeze maximally.The maximum increase of the pressure was identified as the overall maximum squeeze pressure.The maximum resting pressure(MRP)of the anorectal canal at each of the four radial axes,labeled12o’clock(anterior),3o’clock(left),6 o’clock(posterior),and9o’clock(right),was determined and was defined as the maximal pressure on the pressure profile measured while the patient relaxed.The maximal squeeze pressure(MSP)of the anorectal canal pressure profile at each four radial axes,labeled12o’clock,3o’clock,6o’clock,and 9o’clock,was also obtained and defined as the maximal pressure on the pressure profile measured while the patient intentionally squeezed.For further analysis,we divided the anorectal pressure profile into five segments(every20th percentile)to evaluate the effect of the aging process on anorectal pressure.Peak resting anal pressure and peak squeeze pressure were measured at every20th percentile interval of anorectal length along the pressure profile after retraction from the baseline and at every four radial axes labeled12o’clock,3o’clock,6o’clock,and9o’clock (anterior,left,posterior,right).In total,we obtained20 separate peak resting anal pressure(labeled as PRP0–20,

PRP21–40,PRP41–60,PRP61–80,PRP81–100)and20separate peak squeeze anal pressure(labeled as PSP0–20,PSP21–40, PSP41–60,PSP61–80,PSP81–100)measurements for each patient.The0–20th percentile of the pressure profile means 8to10cm proximal of the anal verge,and the81–100th percentile represent the anal pressure measured closest to the anus.

Statistical analysis was performed using the SPSS for Windows(SPSS,Chicago,Illinois,version9.0).De-scriptive analysis reported the data as mean±SD or percentage.Manometric parameters,including the mean overall maximal resting pressure and maximal squeeze pressure of the anorectal canal,were compared between the two groups using the independent Student’s t test. The analyzed variables included age(<65or≥65),parity (≤2or>2),menopause,uterine prolapse,rectocele, urodynamic stress incontinence,detrusor overactivity,and mixed incontinence.The relationships between uterovagi-

nal prolapse(stage0–II),vaginal delivery(n=0–8),age, and MRP or MSP at each of the four radial axes(anterior, left,posterior,right)were examined with a linear regres-sion analysis.Among premenopausal and postmenopausal women,MRP and MSP at each of the four radial axes (anterior,left,posterior,right)were examined with an independent Student’s t test.For further evaluation,a linear regression analysis was used to examine the relationship between age and the anal pressure at every20th percentile interval of the anorectal length along the pressure profile and at each of the four radial axes.The estimated parameters analyzed by linear regression analysis were presented as a regression coefficient and a correlation coefficient.A P value of less than0.05was considered to be a statistically significant.

Results

The mean age of the patients was47.7±12.8years(range, 23–87years),and there were11women(10%)aged over 65years.The characteristics of the study subjects are shown in Table1.The overall maximal resting pressure was 148.8±31.8cmH2O in women under65vs122.5±37.3cmH2O in women aged65or older(P<0.05).The overall maximal squeeze pressure was84±41.9cmH2O in women under65vs153.3±41.8cmH2O in women aged65 or older(P<0.05).Aside from age,no statistically signif-icant differences were found for the other variables between two groups when comparing the overall maximal resting pressure and overall maximal squeeze pressure.

When potential risk factors such as rectocele,vaginal delivery,and age were evaluated for the effects on MRP and MSP at each of the four radial axes(anterior,left, posterior,right),it was found that age leads to a consistent reduction in anal function(Fig.1).Age significantly affected the MRP(correlation coefficient=0.292at12 o’clock axis,0.283at3o’clock axis,0.276at6o’clock axis,0.246at9o’clock axis;all P<0.05)and the MSP (correlation coefficient=0.195at12o’clock axis,0.243at3 o’clock axis,0.197at6o’clock axis,P<0.05;and0.104at 9o’clock axis,P>0.05).Aging attenuated the maximal resting pressure profile at all four axes.Overall,the aging process can explain the10.3%(r2=0.103)reduction in the mean maximal resting anorectal pressure profile.However, the decreasing trend in MRP and MSP seemed to be linear. We did not find any significant difference in MRP and MSP among premenopausal and postmenopausal women along the anorectal pressure profile at each of the four radial axis (all P>0.05,independent Student’s t test).The severity of the rectocele only attenuated MSP at the12and3o’clock axes(correlation coefficient=0.192and0.232,respectively, P<0.05).Vaginal deliveries affected the MRP at the3 o’clock axis only(correlation coefficient=0.212,P<0.05) and the MSP at the12,3,and6o’clock axes(correlation coefficient=0.294,0.336,and0.214,respectively;all P<0.05).Vaginal delivery could only account for11.3% (r2=0.113)of the reduction in MSP at the3o’clock axis.

Furthermore,we analyzed each segment of the sphincter profile using a regression model.The highest peak resting pressure along the anorectal canal pressure profile of the four radial axes were on PRP61–80(120.72cmH2O at12 o’clock,108.17cmH2O at3o’clock,121.64cmH2O at6 o’clock,and118.52cmH2O at9o’clock).The highest peak squeeze pressures of the four radial axes were also found on PSP61–80(147.80cmH2O at12o’clock,131.05cmH2O at3 o’clock,147.67cmH2O at6o’clock,and145.93cmH2O at 9o’clock).The effect of age on resting and squeeze pressure of the anorectal pressure is shown in Table2.Age had a significant negative correlation with resting anal Table1Characteristics of study subjects

Parameters Number of cases

n Percentage Age(years),mean±SD47.8±12.8

Parity(median),range3(0–8)

Menopause3430.9 Uterine prolapse8072.7 Rectocele7770.6 Type of urinary dysfunction

Genuine stress incontinence2825.5 Detrusor overactivity4641.8 Mixed incontinence2522.7 Other1110 Other represents patients with storage or voiding symptoms such

as voiding with abdominal straining,detrusor sphincter dyssynergia, underactive detrusor and bladder outlet obstruction

pressure especially on PRP 61–80at all four radial axes (regression coefficient =?0.650at 12o ’clock,?0.512at 3o ’clock,?0.737at 6o ’clock,and ?0.829at 9o ’clock;all P <0.05)and on PRP 81–100at 12,3,and 6o ’clock (regression coefficient =?0.528,?0.509,and ?0.665,re-spectively;all P <0.05).The negative effect of the aging process was mainly noted from the 41to 100th percentile of the pressure profile (PRP 41–100)at 12and 3o ’clock.The internal anal sphincter,which contributes the most to the resting pressure of the anorectal canal,and the external anal sphincter component and the puborectalis muscle,which play a minor role in the resting pressure,were all compromised by aging.

Similar negative effects of age on the squeeze pressure were noted on PSP 61–80at the 12,3,and 6o ’clock axes (regression coefficient =?0.774,?0.677,and ?0.754,re-spectively;all P <0.05).V oluntary squeeze pressure from the 41to 100th percentile of the pressure profile at the 3o ’clock axis had a significant negative correlation with aging (regression coefficient =?0.597,?0.677,and ?0.751,respectively;all P <0.05).We found that the function of the external anal sphincter and the puborectalis muscle

also

Fig.1The relationship between maximum resting pressure (MRP)and maximum squeeze pressure (MSP)at each of the four radial axes and ages for the 110women with lower urinary tract symptoms.The regression line and correlation coefficient are shown

Table 2Linear regression analysis presenting the effect of age on peak resting pressure (PRP)and peak squeeze pressure (PSP)according to anorectal length and axis

0–20

21–40

41–60

61–80

81–100

Peak resting pressure 12o ’clock ?0.257*?0.174?0.50*?0.650*?0.528*3o ’clock ?0.245?0.191?0.647*?0.512*?0.509*6o ’clock ?0.187?0.185?0.303?0.737*?0.665*9o ’clock

?0.216*?0.171?0.450?0.829*?0.359Peak squeeze pressure 12o ’clock ?0.307*?0.187?0.575?0.774*?0.5123o ’clock ?0.271*?0.265?0.597*?0.677*?0.751*6o ’clock ?0.249*?0.174?0.398?0.754*?0.5229o ’clock

?0.240*

?0.188

?0.253

?0.495

?0.520

The estimated parameters are presented as a regression coefficient *P <0.05

decreased with the aging process.In addition,a negative correlation between age and squeeze pressure was noted on PSP0–20of all the four radial axes(but only a weak correlation).

Discussion

Our results demonstrate that increasing age leads to a significant decline in anorectal function including resting pressure and voluntary squeeze pressure in women already suffering from lower urinary tract symptoms.These results imply that increasing age is mainly associated with weaker basal tone of the internal anal sphincter at rest and a loss of strength in the external anal sphincter during maximal pelvic floor contraction.Effects of vaginal deliveries and rectocele play a minor role.These two variables do not affect the attenuation of the squeeze pressure and resting anorectal pressure as much(especially at the3o’clock axis).

McHugh and Diamant[14]reported that aging in women is associated with a consistent reduction in the resting anal canal pressure and the maximal squeeze pressure.Haadem et al.[4]revealed that closing pressure(i.e.,the difference between maximal resting anal pressure and rectal pressure) reduces more markedly with age than maximal resting anal pressure.Jameson et al.[15]found that increasing age leads to perineal descent at rest,slow pudendal nerve conduction, a fall in resting anal pressure,and decreased anorectal sensory function.Ryhammer et al.[2]also found that age leads to a consistent and gradual reduction in anal function and variables including perineal position at rest,descent during straining,maximal resting pressure,and maximal squeeze pressure of the anal sphincters,and pudendal nerve terminal motor latency is also affected.Our results are similar to their findings.However,Haadem et al.and Ryhammer et https://www.wendangku.net/doc/cf10866411.html,ed a single lumen and a catheter with two holes,one each side to measure a single sphincter profile.McHugh et https://www.wendangku.net/doc/cf10866411.html,ed four openings and a four-channel catheter(the same as ours)to yield pressure determinations for four axes,but they averaged their data to yield a maximal pressure for comparison.Investigators from these three groups did not individually analyze the pressure derived from each axis.In our study,we analyzed each axis individually to clarify the axis-specific defect in the sphincter profile and to locate site-specific damage of the anorectal sphincter,especially for controlling confound-ing variables such as vaginal deliveries or an anatomical defect(rectocele).One of two articles published in the late 1980s revealed that age did not affect anal length,highest anal resting tone,anal pull-through pressures(obtained during rest and voluntary squeeze),threshold of the recto-sphincteric reflex,amplitude of rectosphincteric reflex with 60ml rectal distension,threshold of sensation,critical volume,and rectal wall elasticity[16].The pressure transducer was a single channel.Another report by Laurberg and Swash[3]showed that a reduction in anorectal squeeze pressure was found in the fifth decade,but the resting anal pressure remained unchanged using the St.Mark’s micro-balloon method.At the same time,they found that the reduction in squeeze anal pressure was accompanied by an increase in the mean pudendal nerve terminal motor latency and increased perineal descent in the resting and straining positions.The results of these two studies did not coincide with ours.The pressure measured by the investigators of these two groups does not reflect the differences of sterical pressure distribution at each radial axis.

In this study,we did not find any significant difference in MRP and MSP among premenopausal and postmenopausal women along the anorectal pressure profile at each of the four radial axes.Our results are consistent with the findings of Ryhammer et al.[17], who reported that aging effects on anorectal sensibility are largest in postmenopausal women,whereas only slight changes with age are seen in young and middle-aged women.However,they found that the decrease in maximal squeeze pressure is linear.Age-related changes of anorectal pressure seem to be gradual throughout adult life rather than occurring abruptly after menopause.

Regarding the effect of vaginal deliveries on anorectal function,results are conflicting.Some literature has demon-strated that parity is unrelated to and has no effect on changes in anal pressure[4,14].Jameson et al.[15]found that parity leads to a lower squeeze pressure.Tetzschner et al.[18] showed that obstetric anal sphincter rupture is associated with a risk of approximately50%for developing either anal or urinary incontinence,or both,2to4years postpartum.In their study,13of72women(18%)had both anal and urinary incontinence.Our results showed that vaginal deliveries affected MRP at the3o’clock axis only and MSP at the12,3,and6o’clock axes.Vaginal delivery could only explain11.3%of the reduction in MSP at the3o’clock axis.We postulate that childbirth may damage the pudendal nerves caused by birth canal lacerations,which might have a minor effect on the internal anal sphincter innervated by the autonomic nervous system and a major effect on the external anal sphincter unilaterally innervated by pudendal nerves,especially at the left sectors of the circumference of the anus.Whether this is associated with a higher percentage of newborns being delivered in the left occipital anterior head position still needs to be clarified in a future study.

The effect and significance of a rectocele on the anal sphincter pressure seems to be vague and difficult to account for.Rotholtz et al.[19]revealed that a rectocele ≥4cm in maximal diameter,as measured during an evacuatory effort during cinedefecography,had a higher first sensation volume,capacity,and compliance.We only

looked for stage I and II rectoceles affecting the anorectal sphincter pressure.We found that the presence of a rectocele was accompanied by a reduction in MSP at the 12and3o’clock axes.Further investigation needs to be conducted to elucidate the role of this kind of anatomical defect in anorectal function.

To locate and clarify the axis-specific defect or site-specific damage in the sphincter profile when designing this study,we divided the pressure profile into five segments and obtained20separate peak resting anal pressures.Most of the negative effects of aging focused on the middle and lower third of the resting pressure profile(PRP41–100) located at the12and3o’clock axes.It was noted that the squeeze pressure had a significant reduction on PSP61–80at the12,3,and6o’clock axes(regression coefficient=?0.774,?0.677,and?0.754,respectively;all P<0.05). V oluntary squeeze pressure at the middle and lower third (PSP41–100)of the profile at the3o’clock axis had a significant negative correlation with aging(regression coefficient=?0.597,?0.677,and?0.751,respectively;all P<0.05).These findings suggest that aging compromises the basal tone of the internal anal sphincter mostly at the12 and3o’clock axes(i.e.,anterior and left).During voluntary squeezing,the function of the external anal sphincter and the puborectalis muscle at the12,3,and6o’clock axes (anterior,left,and posterior;especially at the3o’clock axis, left)also attenuated due to the aging process.

There are limitations in our present study.First,there is no consensus regarding the depth of the pressure catheter inserted during anorectal manometry testing.In our study, we chose to place the pressure catheter10cm into the anorectum,above the anal verge.Recent studies[20]show the puborectalis to be consistently at6cm proximal to the anal verge.Although there might be an ethnic difference in this anatomical correlation,we could not exclude the possibility that increased length might confound the data by falsely elevating pressure due to a volume effect. Second,a future study may be needed to compare our group to age-matched controls without lower urinary tract symptoms to validate the fact that age is an independent variable as noted in our present study.

In conclusion,our results show that anal pressure profilometry along the anorectal canal is complex.This may explain the difficulty in discriminating between continent and incontinent patients with an anal manometry examination.Aging is associated with reduced anorectal pressure,especially at the middle and lower third of the anorectal canal,in patients with lower urinary tract symptoms.The anterior and left lateral sides of the anorectal sphincter(12and3o’clock axes)seem to be vulnerable during the aging process.References

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