Anorectal manometry: Experience with strain gauge pressure transducers for the diagnosis of Hirschsprung's disease

Anorectal Manometry: Experience With Strain Gauge Pressure Transducers for the Diagnosis of Hirschsprung's Disease By Vera A. Loening-Baucke

Iowa City, Iowa 9 An esophageal pressure transducer with three strain gauges was used in the anal canal to s t u d y the rectosphincteric reflex (RSR) in five infants and children with intestinal obstruction, 142 children age one day to 18 years with m o d e r a t e t o severe constipation and in 18 healthy c o n t r o l children 4 to 12 years of age. The RSR w a s p r e s e n t in t h e four n e w b o r n s w i t h intestinal obstruction, in 133 of the c o n s t i p a t e d children, and in all healthy controls. The mean (_+SD) minimal v o l u m e of air in t h e rectal balloon required to produce RSR >_ 5 mm Hg (RSRT} was 9 mL (_+2) for infants 0 to 2 years, 14 mL (_+4) for children 2 t o 4 years, 15 mL (-+6) for children 4 to 12 years, and 14 mL (_+6) for children 12 to 18 years of age. The RSRT for c o n t r o l children w a s 13 mL (_+4). The volume of air used in rectal balloon distension correlated with the amplitude of the RSR for control (r = 0.7131) and constipated children (r = 0.6289). The amplitudes of t h e RSR for t h e controls w e r e significantly higher than the amplitudes for constip a t e d children for rectal distension volumes between 60 and 15 cc (P < 0.01). T h e 10 children with absent RSR had Hirschsprung's disease confirmed at surgery. Measurements of RSR could be used to separate patients with chronic constipation from patients with Hirschsprung's disease. INDEX W O R D S : Anoroctal manometry; rectosphinctoric reflex; chronic constipation; Hirschsprung's disease; aganglionic megacolon,

he internal anal sphincter provides most of the tone in the anal canal, and rectal distension inhibits internal anal sphincter tone. This inhibition results in a fall in the pressure in the anal canal, and this phenomenon is referred to as the rectosphincteric reflex (RSR). This response was first reported by Gowers 1 in 1878. The clinical significance of the fact that transient rectal distention produces an RSR in patients with chronic constipation but not in patients with Hirschsprung's disease (congenital aganglionic megacolon) was recognized by Callaghan and Nixon 2 and Tobon et al? In recent publications 4-6 the R S R was reported to be nondiagnostic in about 25% of newborns and in 8-16% of children with congenital aganglionic megacolon or chronic constipation. In these studies RSR was determined with

T

Journal of Pediatric Surgery, Vol. 18, No. 5 (October), 1983

either a tandem system of two side-opened perfused catheters, 4 air or water-filled balloons, 5 or a closed water-filled system. 6 This report reviews my experiences with the use of a different recording technique for RSR. The findings indicate that measurements of RSR can be used in differentiating children with chronic constipation from those with Hirschsprung's disease. MATERIALS AND METHODS

The subjects were 147 consecutive infants and children, 91 boys and 56 girls, ages 1 day to 18 years (mean age 6.3 years) seen between July, 1978, and December, 1980, at the Pediatric Clinics at the University of Iowa Hospitals and Clinics. Most patients were suspected of having congenital aganglionosis of the bowel. Patients had a history of chronic constipation, defined as difficulty in elimination of feces such as infrequent defecation, stools with hard and dry consistency, or insufficient quantity of stools. Four newborns <12 days of age and one 8-year-old presented with intestinal obstruction. Fecal soiling was often elicited in the history. Eighteen healthy control children with no history of gastrointestinal complaints, 14 boys and 4 girls, ages 4 to 12 years (mean age 8.7 years) were also studied. The study was approved by the appropriate institutional Human Research Review Committee. A written informed consent was obtained from all subjects. Instruments

As an anorectal probe, an esophageal pressure transducer, made of a 5 ram-diameter, flexible silicone rubber tube containing 3 strain gauges was used (Model MP-3, Honeywell Biomedical Instrumentation, Denver, CO). The strain

From the Division of Ambulatory and Community Pediatrics, Department of Pediatrics, The University of Iowa Hospitals and Clinics, Iowa City, Iowa. Supported in part by BSRG Grant S07 RR05372-16 awarded by the Biomedical Research Support Grant Program, Division of Research Resources, National Institutes of Health, and by Grant MO1-RR~OO59 from the General Clinical Research Center Program, Division of Research Resources, National Institutes of Health. Address reprint requests to Dr Vera Loening-Baucke, Department of Pediatrics, University Hospitals, Iowa City, 1,4 52242. 9 1983 by Grune & Stratton, Inc. 00 22-3468/8 3/180 5~016501.00/0

895

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VERA A. LOENING-BAUCKE

gauges were spaced 5 cm apart and were staggered at 120 ~ intervals around the probe. The tube was marked in 1 cm increments to provide external reference for strain gauge position in the anal canal and rectum. A 2.5 by 3 cm latex balloon (made from a simple finger cot) was attached to one end of a thin polyethylene tube (2.4 mm outer and 1.7 mm inner diameter). The latex balloon was tied to the tip, and its polyethylene tube along the side of the esophageal pressure transducer. The ballon was used for transient distension of the rectum with measured volumes of air (Fig. 1). The addition of this thin polyethylene tube made the instrument rigid enough to be placed through the anus into the rectum without an anoscope. The anorectal instrument was fixed in position by taping it to the child's buttocks. The output of the strain gauges was fed into the amplifiers of a 4-channel dynograph recorder (Beckman R-611, Beckman Instruments, Schiller Park, IL) and was graphed on running paper. Procedure

One or two Fleet enemas were administered to the children to clear large fecal masses at least 1 hour prior to testing. The children were not sedated. Stories were read to preschool-age children to relax them, and restless newborns and infants relaxed while sucking on pacifiers or drinking from a bottle. The R S R was evaluated in all children with the strain gauge placed 1 to 1.5 cm above the anal verge (distal boundary of the anal canal), because previous studies had shown the anal tone to be highest in this region of the anal canal. 7 The balloon lay at either 6, 11, or 16 cm proximal to the anal verge. Transient rectal distension for 1 second was

801mm Rg

4o 20

//T

anal tone

Transducer l c m

am Iitu 9 o

RSR

above anal verge

Fig. 2. Recording of anal tone and normal rectosphincteric reflex (RSR) in a child with chronic constipation and encepresis. 1[ indicates transient rectal balloon inflation with 60 cc of air. The amplitude of RSR is the difference b e t w e e n the lowest anal tone during a 5-second period immediately before the rectal distension to the lowest point of the relaxation.

accomplished by injecting air with a syringe into the tubing of the rectal balloon and withdrawing the air immediately. The smallest volume in cc of air which resulted in RSR _>5 mm Hg, the RSR threshold (RSRT), was determined in children _>4 years of age by introducing air volumes of 60, 50, 40, 30, 25, 20, 15, 10, and 5 cc into the rectal balloon, initialed each time with no air in the balloon. In children 6 months to 4 years of age air volumes of 30, 25, 20, 15, 10, and 5 cc, and in infants <6 months old, 15, 10, and 5 cc of air were used for the transient rectal balloon distension. The RSR was considered present when 3 successive pressure falls of _>5 mm Hg were recorded within 2 seconds, following the ballpon distension and when prolonged balloon distension resulted in a pressure fall with recovery of the anal tone prior to release of the rectal distension. The amplitude of RSR was the difference between the lowest anal tone during a 5-second period immediately before the rectal distension and the lowest point of the relaxation (Fig. 2). STATISTICAL A N A L Y S I S

The differences between the mean values of t h e p a r a m e t e r s m e a s u r e d in t h e c o n t r o l a n d constipated children were analyzed by the stud e n t ' s t - t e s t for u n p a i r e d d a t a , b y a n a l y s i s o f v a r i a n c e , a n d l i n e a r r e g r e s s i o n . 8'9 levator ani Sphincter ni internus

Sphincter

i externus

Fig. 1. Schematic Diagram of Recording Technique. The distal strain gauge of the M P - 3 esophageal pressure transducer is located in the lower part of the anal canal. The rectal balloon used for stimulating changes in sphincter tone is shown distended.

RESULTS

No sex-related differences of RSRT were n o t e d , t h e r e f o r e , in s u b s e q u e n t a n a l y s e s d a t a for boys and girls were combined. A l l 18 c o n t r o l c h i l d r e n h a d R S R p r e s e n t ; t h e mean (• R S R T w a s 13 (_+4) cc, a n d t h e r a n g e w a s 10 to 25 c c o f air. R S R c o u l d b e e l i c i t e d in 1 3 7 ( 9 3 % ) o f t h e 147 p a t i e n t s w i t h either chronic constipation or intestinal obstruction. The mean (• R S R T w a s 14 (_+6) cc, r a n g e 5 to 3 0 c c o f air. T h e s e r e s u l t s w e r e n o t statistically different from those for the control c h i l d r e n . A l l 10 c h i l d r e n (9 b o y s a n d 1 g i r l ) i n whom RSR was not elicited had Hirschsprung's

A NEW METHOD FOR ANORECTAL MANOMETRY

disease, documented by the absence of myenteric and submucosal ganglion cells in the rectal wall biopsy. For subsequent analysis, the patients were arbitrarily divided into 4 age groups. Group 1 consisted of 28 children, 15 boys and 13 girls, less than 2 years of age. 24 children had R S R present. Four boys with Hirschsprung's disease had no RSR. The mean (_+SD) R S R T was 9 (_+2) cc, and the range was 5 to 10 cc of air. Four full-term newborns with intestinal obstruction were included in this group. All four had R S R present; their mean (_+SD) R S R T was eight (+_2) cc, and the range was 5 to 10 cc of air. Group 2 included 18 constipated children, 12 boys and 6 girls, 2 to 4 years of age. All 18 children had R S R present. The mean ( _ S D ) R S R T was 14 (_+4) cc, and the range was 10 to 20 cc of air. Group 3 was made up of 87 children, 56 boys and 31 girls, 4 to 12 years of age. 83 patients had R S R present; the mean (_+SD) R S R T was 15 (_+6) cc, and the range was 5 to 30 cc of air. R S R could not be elicited in four boys, who had Hirschsprung's disease. Group 4 included 14 constipated teenagers, 8 boys and 6 girls, 12 to 18 years of age. Twelve children had R S R present; the mean (+_SD) R S R T was 14 (_+6) cc, and the range was 5 to 25 cc of air. R S R was absent in one 18-year-old girl and one 15-year-old boy who had Hirschsprung's disease. The influence of the distance of the rectal balloon from the anal verge on R S R T was studied in three controls and ten patients. Mean (_+SD) R S R T s in the three controls were 13 (___3), 13 (_+3), and 12 (_+3) cc of air for rectal balloon placement at 6 cm, 11 cm, and 16 cm above the anal verge. Mean R S R T s in the ten constipated children were 17 (+-7), 15 (_+7), and 15 (+-5) cc of air, respectively. R S R T appeared to be independent from balloon position in the rectum. Progressive decrease in volume of air used for rectal balloon distension from 60 to 5 cc of air was associated with progressive decrease in amplitude of R S R in the 18 control and 62 constipated children 4 to 18 years of age evaluated. The correlation coefficient "for the relationship of the volume of balloon distension and amplitude of R S R was 0.7131 for control and

597

0.6955 for constipated children. The rectal distension volume correlated to the amplitude of R S R for volumes between 30 and 5 cc for control (r = 0.6518) and for constipated children (r = 0.6289). However, the slope of the graph for control children was significantly different from the slope of the graph for children with constipation (P < 0.01) (Fig. 3). On the other hand, the amplitude of R S R was linearly related to rectal distension volumes between 60 and 30 cc of air. The slopes of the graph which relates the amplitude of R S R to the rectal distension volume of control compared to constipated children were not significantly different (P = 0.91), whereas the respective intercepts were significantlydifferent from each other (P < 0.001). This meant that the two lines were parallel (Table 1 and Fig. 3). A wide variation in the amplitude of R S R was, however, noted, which resulted in a correlation coefficient for the amplitude of R S R versus rectal distension volume of 0.2793 for control and 0.3043 for constipated children. The amplitudes of R S R for rectal distension volumes between 60 and 15 cc were significantly larger for control than for constipated children at equivalent volumes (P < 0.01), but not for distension volumes of 10 and 5 cc. This relationship appears to hold for all ages of children studied. R S R was abnormal in 10 (7%) of the 147 patients; all had Hirschsprung's disease. In these patients, the internal anal sphincter tone did not change (in 58%) (Fig. 4), increased (in 30%), or decreased (in 12%) after transient rectal distensions with air volumes between 5 and 60 cc. The decreases in tone were in 9% of abnormally short duration (1 to 2 seconds) and were only observed when the rectal balloon lay 6 to 7 cm above the anal verge. Relaxations of normal appearance were recorded sporadically (3%), but at no time were 3 successive relaxations obtained. DISCUSSION

In this study a flexible, smooth, small-diameter instrument with a strain gauge was used to measure sphincter tone directly from the anal canal. The small diameter of the instrument and the ability to measure tone directly from the anal region made the test more accurate. The rectosphincteric reflex proved reliable in the four newborns with intestinal obstruction. All four are

V E R A A. L O E N I N G - B A U C K E

598

AMPLITUDE

RSR

OF

(ram Hg)

, Control

9

e..,,-.-,.,.,..--~Co n st i p a t e d C h i l d r e n ~ 4 yrs /..-.-..-.-/Constipated Children -> 4 - 1 8 yrs

'liltliliji~I I 9 ~

""...y.

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.....

" " u

"~

o

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60

5;'0 RECTAL

DISTENSION

4() VOLUME

3"0

2.5

.

2. 0

.

15

10

.Y

(cc)

Fig. 3. Relationship between the amplitude of the rectosphincteric reflex (RSR) in m m H g and the rectal distension volume between 60 and 5 cc of air in 18 control children, 62 children >--4 years of age, and 27 children < 4 years of age.

doing well and have continued with normal bowel movements during their first year of life. In previous studies, Boston ~~ obtained RSR in all newborns 28 hours of age, and Verder" found RSR present as early as 2 hours after birth in mature as well as premature newborns. Other authors ~2-t4 reported difficulties with anorectal manometry in the very young infant, with delay of an RSR up to the twelfth day of life. ~3 No false-negative results were obtained. Histologic data were available for 14 patients with normal RSR, and all had ganglion cells present. No false positive diagnosis was made by manometry. All patients with absent RSR had Hirschsprung's disease. Earlier studies in older infants, children, and adults suggested that anorectal manometry is a reliable, safe method for the diagnosis of Hirschsprung's disease. 1z'~5-!8 However, more recent publications reported inaccuracies of the manometric test in children with error rates of 8% to 16%, including false negative as well as false positive results. 4'6

In all studies nonrelaxation or contraction of the internal anal sphincter has been documented in patients with Hirschsprung's disease. Some authors have also found occasional recordings resembling relaxation of the internal anal sphincter produced by artifact. 4'6 As a result of my experience during the last 30 months, I have observed and experienced several possible pitfalls in the manometric test. The most important requirement of the test was a resting child, since a restless child can contract the external anal sphincter and thereby override the normal drop in pressure after rectal distension. Infants and toddlers were tested during feeding or naptime; preschool-age children were usually quieted long enough when distracted by a storybook. In none of the children examined was sedation necessary or could the test not be performed due to restlessness. Air volumes in the very young child should be small, because sensation of balloon distension may induce movement, usually drawing up of the

A NEW METHOD FOR ANORECTAL MANOMETRY

599

Table 1. The Relationship of the Amplitude of the Rectosphincteric Reflex (RSR) to Rectal Distension Volume Between 60 and 30 cc of Air by Analysis o f Covarlance Sum of Squares

Source Group effect Regression for the distension volume Test for parallelism

446.3 2,942.3 1.97

F Value

P> F

3.00 19.8

0.08 0.0001

0.01

0.91

legs, resulting in increase of external anal sphincter pressure. Because results are constant and predictable for rectal distension volumes between 30 and 60 cc in children over 4 years of age, studies of RSR should be conducted with volumes between 30 and 60 cc of air. Placement of the distending balloon 16, 11, or 6 cm from the anal verge did not influence RSR and R S R T in control and constipated children. The placement of the rectal balloon 6 to 7 cm

601

mm HI;

above the anal verge should be avoided because recordings resembling a short-lasting internal sphincter relaxation were observed occasionally in six patients with Hirschsprung's disease. These abnormal relaxations occurred only when the rectal balloon lay 6 cm above the anal verge and distending volumes >_40 cc were used, and were not seen with the rectal balloon located 11 and 16 cm above the anal verge. Short-lasting displacement of the transducer out of the high pressure zone of the anal canal or accidental mechanical distension of the anal canal could explain this phenomenon. A safeguard to help to recognize this recording error is the prolonged distension of the rectal balloon, which would result in an unusual, long-lasting decrease in anal tone. 6 RSR was easily identified in most recordings. It is important, however, that the strain gauges be placed into the area with the highest anal

Transducer 11. 5cm above anal verge

0

60 T mm HI; 40

T r a n s d u c e r 6 . 5 c m a b o v e anal v e r g e

/

60.

mm Hi;

Transducer

1 . 5 c m above anal veri;e

40. 20-

seconds

60 cc

60 cc

60 cc

Fig. 4. Hirschsprung's disease. Tracing from a 14-year-old male with chronic constipation since age 9 years and intermittent encopresis. The internal anal sphincter (transducer position 1.5 cm above anal verge) is unaffected by distension with air for 1 second ( 1~) of the rectal balloon placed 17 cm above the anal verge.

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VERA A. LOENING-BAUCKE

resting tone, which is 1 to 1.5 cm above the anal verge. In two patients, a 2-day-old infant and an 8-year-old girl, the tone in the anal canal at rest was low (_<10 m m H g ) and t h e r e f o r e the amplitude of R S R was small (_<10 m m H g ) . A n inexperienced e x a m i n e r m a y have difficulties in identifying the small relaxation of the internal anal sphincter. This pitfall can be m i n i m i z e d by d o c u m e n t i n g anal tone, while the strain g a u g e is slowly (0.5 c m / 2 sec) pulled from the r e c t u m t h r o u g h the anal canal.

A n o r e c t a l m a n o m e t r y is an a t r a u m a t i c test for the diagnosis of H i r s c h s p r u n g ' s disease and provides an a c c u r a t e diagnosis of this disorder in adults, children, and neonates. A n o r m a l R S R m a d e the b a r i u m e n e m a e x a m i n a t i o n and rectal wall biopsy unnecessary in > 9 0 % of patients who presented with c o m p l a i n t s of severe chronic constipation or intestinal obstruction. ACKNOWLEDGMENT

I wish to acknowledge the kindness of Dr Robert Soper for allowing me to study his patients.

REFERENCES

1. Gowers WR: The automatic action of the sphincter ani. Proc Roy Soc Lond 26:77-84, 1878 2. Callaghan RP, Nixon HH: Megarectum: Physiological observations. Arch Dis Child 39:153-157, 1964 3. Tobon F, Nigel C, Talbert J, Schuster M: Nonsurgical test for the diagnosis of Hirschsprung's disease. New Engl J Med 278:188-194, 1968 4. Meunier P, Marechal JM, Mollard P: Accuracy of the manometric diagnosis of Hirschsprung's disease. J Pediatr Surg 13:411-415, 1978 5. McParland FA, Olness K: Diagnostic uses of anorectal manometry in pediatrics. Minn Med 62:447-450, 1979 6. Morikawa Y, Donahoe PK, Hendren WH: Manometry and histochemistry in the diagnosis of Hirschsprung's disease. Pediatrics 63:865-871, 1979 7. Loenig-Baucke VA, Younoszai MK: Abnormal anal sphincter response in chronically constipated children. J Pediatr 100:213-218, 1982 8. Huntberger DV, Leaverton PE: Statistical Inference in the Biomedical Sciences. Boston: Allyn and Bacon, 1970 9. Snedecor GW, Cochran WG: Statistical Methods. Ames, Iowa: Iowa State University Press, 1967 10. Boston VE, Cywes S, Davies MRQ: Qualitative and quantitative evaluation of internal anal sphincter function in the newborn. Gut 18:1036-1044, 1977 11. Verder H, Krasilnikoff PA, Scheibel E: Anal tonome-

try in the neonatal period in mature and premature children. Aeta Pediatr Scand 64:592-596, 1974 12. Howard ER, Nixon NH: Internal anal sphincter: Observations on development and mechanism of inhibitory responses in premature infants and children with Hirschsprung's disease. Arch Dis Child 43:569-578, 1968 13. Holschneider AM, Kellner E, Streibl P, et al: The development of anorectal continence and its significance in the diagnosis of Hirschsprung's disease. J Pediatr Surg 11:151-156, 1976 14. Ito Y, Donahoe PK, Hendren WH: Maturation of the rectoanal response in premature and perinatal infant,s. J Pediatr Surg 12:477~,82, 1977 15. Schuster MM, Hookman P, Hendrix TR, et al: Simultaneous manometric recording of internal and external anal sphincteric reflexes. Bull Johns Hopkins Hosp 116:79-88, 1965 16. Tobon F, Schuster MM: Megacolon: Special diagnostic and therapeutic features. John Hopkins Med J 135:91105, 1974 17. Verder H, Johansen KS, Engbaek K: Anal tonometry. Acta Pediatr Scand 62:59-65, 1973 18. Frenckner B: Ano-rectal manometry in the diagnosis of Hirschsprung's disease in infants. Acta Pediatr Scand 67:187-192, 1978