The effect of ketamine anesthesia on anorectal manometry

Impact of anesthesia drugs on digestive motility measurements in humans: A systematic review

BACKGROUND AND PURPOSE

Measurement of gastro-intestinal motility is increasingly performed under general anesthesia during endoscopic or surgical procedures. The aim of the present study was to review the impact of different anesthetic agents on digestive motility measurements in humans.

METHODS

This systematic review was performed using the Medline-Pubmed and Web of Science databases. All articles published until October 2023 were screened by identification of key words. Studies were reviewed if patients had an assessment of digestive motility using conventional perfused manometry, high-resolution manometry, electronic barostat or functional lumen impedance planimetry with the use of inhaled or intravenous anesthetic anesthetic agents (propofol, ketamine, halogens, nitrous oxide, opioids, and neuromuscular blockades).

RESULTS

Four hundred and eighty-eight unique citations were identified, of which 42 studies met the inclusion criteria and were included in the present review. The impact of anesthetics was mostly studied in patients who underwent esophageal manometry. There was a heterogeneity in both the dose and timing of administration of anesthetics among the studies. Remifentanil analgesia was the most studied anesthetic drug in the literature, showing a decrease in both distal latency and lower esophageal sphincter pressure after its administration, but the impact on Chicago classification was not studied. Inhaled anesthetics administration elicited a decrease in lower esophageal sphincter pressure, but contradictory findings were shown on esophageal motility following propofol or neuromuscular blocking agents administration.

CONCLUSION

Studies of the impact of anesthetics on digestive motility remain scarce in the literature, although some agents have been reported to profoundly affect gastro-intestinal motility.

Accuracy of Anorectal Manometry to Detect the Rectoanal Inhibitory Reflex in Children: Awake Versus Under General Anesthesia

OBJECTIVES

Our objective was to investigate if there is a difference in the detection of the rectoanal inhibitory reflex (RAIR) when an anorectal manometry (ARM) is performed awake or under general anesthesia.

METHODS

A retrospective review of ARM studies was performed to identify children who had undergone ARMs both while awake and under general anesthesia. We compared ARM outcomes including the detection of the RAIR and anal canal resting pressure.

RESULTS

Thirty-four children had received ARMs both while awake and under general anesthesia (53% female, median age at first ARM 7.5 years [range 3-18 years]). In 9 of 34 (26%) children the RAIR was solely identified during ARM under general anesthesia and not during ARM while awake. In 6 of 9 (66%) this was unrelated to the balloon volumes used during balloon inflations. In 4 of 34 (12%) children, assessment of the RAIR was inconclusive during ARM under general anesthesia due to too low, or loss of anal canal pressure. In 2 of those children, ARMs while awake showed presence of a RAIR. Anal canal resting pressures were higher during ARM while awake versus ARM under general anesthesia (median 70 [interquartile range, IQR 59-85] vs 46 mmHg [IQR 36-65] respectively, P < 0.001).

CONCLUSIONS

General anesthesia may affect the detection of a RAIR in 2 ways. On the one hand, it may facilitate better visualization in children in whom a RAIR could not be visualized while awake. On the other hand, it may cause a loss of anal canal pressure resulting in an inconclusive test result.

Can Propofol Be Used to Assess the Presence of the Rectoanal Inhibitory Reflex During Anorectal Manometry Studies?

OBJECTIVES

To study changes in intra-anal pressure (IAP) and characteristics of the rectoanal inhibitory reflex (RAIR) during anorectal manometry (ARM) in patients undergoing anesthesia induction with propofol.

METHODS

Prospective study in which ARM was performed at baseline while patients were awake and repeated after propofol-induced anesthesia. We studied IAP and the presence and characteristics of the RAIR before and after propofol.

RESULTS

A total of 27 patients were included (63% male; 9.2 years). Three patients had obstructive symptoms after Hirschsprung disease repair (HSCR), and 24 had intractable constipation. At baseline, the RAIR was present on 21 of 27 patients and absent on 6 of 27. Of the six patients with an absent RAIR, it remained absent in four of six (three known HSCR, and one new diagnosis of IAS achalasia), and two of six had a normal RAIR during propofol. Therefore, RAIR was present in all patients with constipation. The mean resting IAP was significantly lower after propofol. The percentage of IAS relaxation after lower balloon volume inflations was significantly higher during propofol (P < 0.05). No difference was observed over the latency time or the total relaxation time after propofol.

CONCLUSIONS

Propofol can be used to assess the presence of the RAIR during ARM in children who are uncooperative and undergoing other procedures under anesthesia. On the other hand, propofol significantly reduces the resting IAP and increases the percentage of internal anal sphincter relaxation after balloon distention. These findings may impact the interpretation to decide if an intervention is needed, or if there is a possible spinal neuropathy.

Anorectal manometry in pediatric settings: A systematic review of 227 studies

BACKGROUND

There is wide variation in the clinical use of diagnostic tools for children with chronic constipation and functional/structural fecal incontinence (CCFSFI). Anorectal manometry (ARM) is a well-recognized technique to assess the function of the anorectum.

PURPOSE

Our aim was to perform an up-to-date review on ARM in pediatric patients with CCFSFI, with specific focus on the indication of use and protocol. Variation of its use in pediatrics will be explored.

METHODS

A systematic search was conducted for empirical studies utilizing ARM with a pediatric sample. A keyword search of literature published in English before July 2018 was conducted and updated to October 2019. Data on demographics, clinical information, study aims, ARM parameters and use of sedation/anesthesia were collected.

KEY RESULTS

A total of 227 studies were included in this systematic review. The age of study participants at the time of ARM ranged from birth to 18 years. ARM was most commonly used in patients with organic conditions (65%) compared to functional constipation (41%). In almost half [108/227 (48%)] of the studies, ARM was performed awake. The ARM parameters most frequently assessed were the rectoanal inhibitory reflex, which was evaluated in 198/227 studies (87%) and the anal resting pressure [166/227 studies (73%)].

CONCLUSIONS AND INFERENCES

This systematic review has highlighted the vast variation of ARM use within pediatrics and the need to strive toward standardization and use of consensus guidelines. We anticipate this will further advance our understanding of the pathophysiological mechanisms involved in children with defecation disorders.

Scientific solution to a complex problem: physiology and multidisciplinary team improve understanding and outcome in chronic constipation and faecal incontinence

PURPOSE

There is a lack of diagnostic credibility to direct focused management for children with chronic constipation (CC) and faecal incontinence (FI). The aim is to assess the impact of an innovative Children's Anorectal Physiology Service (CAPS) focusing on improving outcomes in children with CC/FI.

METHODS

Prospective data: demographics, bowel and quality of life (QoL)/risk of distress questionnaires. Diagnostics: awake high-resolution anorectal manometry (AHRAM), endoanal ultrasound and transit marker studies (TMS).

RESULTS

Total patients: 112; 66 males (59%); median 9 years (17 months to 16 years). Patient groups included: 89 (79%) had functional CC/FI; 9 (8%), Hirschsprung's disease; 12 (11%), anorectal malformations and 2 (2%), trauma. St Marks Incontinence score (SMIS) abnormal in 91 (81%) and Cleveland Constipation Score (CCS) in 101 (90%) patients. Anorectal manometry: 94 (84%) awake and 18 (17%) under anaesthesia. Play specialist input 37 (33%) patients. AHRAM abnormal 65 (58%): sphincter dysfunction 36 (32%) and altered rectal sensation: hyposensitive 22% (20/91); 21% (19/91) hypersensitive. TMS normal in 64 (57%), 17 (15%) slow transit and 27 (24%) rectal evacuatory disorder. Risk of distress in 38% and poor QoL in 55% patients which correlated with abnormal SMIS (p = 0.02). Patient/parent satisfaction improved significantly (p < 0.05).

CONCLUSIONS

Scientific investigations combined with multidisciplinary team improve patient satisfaction and reduces patient self-report illness severity. A complex problem requires a scientific solution.

An ANMS-NASPGHAN consensus document on anorectal and colonic manometry in children

BACKGROUND

Over the last few years, the study of the colon and anorectal function has experienced great technical advances that have facilitated the performance of the tests and have allowed a more detailed characterization of reflexes and motor patterns. As a result, we have achieved a much better understanding of the pathophysiology of children with defecation problems. Anorectal and colonic manometry are now commonly used in all major pediatric referral centers as diagnostic tools and to guide the management of children with intractable constipation and fecal incontinence, particularly when a surgical intervention is being considered.

PURPOSE

This review highlights some of the recent advances in pediatric colon and anorectal motility testing including indications and preparation for the studies, and how to perform and interpret the tests. This update has been endorsed by the North American Society for Pediatric Gastroenterology, Hepatology and Nutrition (NASPGHAN).

Anorectal manometry with and without ketamine for evaluation of defecation disorders in children

INTRODUCTION

Anorectal manometry (ARCM) provides valuable information in children with chronic constipation and fecal incontinence but may not be tolerated in the awake child. This study aimed to evaluate the effect of ketamine anesthesia on the assessment of anorectal function by manometry and to evaluate defecation dynamics and anal sphincter resting pressure in the context of pathophysiology of chronic functional (idiopathic) constipation and soiling in children.

METHODS

This was a prospective study of children who were investigated for symptoms of chronic constipation and soiling between April 2001 and April 2004. We studied 52 consecutive children who had awake ARCM, biofeedback training and endosonography (awake group) and 64 children who had ketamine anesthesia for ARCM and endosonography (ketamine group). We age matched 31 children who had awake anorectal studies with 27 who had ketamine anesthesia.

RESULTS

The children in awake and ketamine groups were comparable for age, duration of bowel symptoms and duration of laxative treatments. ARCM profile was comparable between the awake and the ketamine groups with regard to anal sphincter resting pressure, rectal capacity, amplitude of rectal contractions, frequency of rectal and IAS contractions and functional length of anal canal. Of 52 children who had awake ARCM, dyssynergia of the EAS muscles was observed in 22 (42%) and median squeeze pressure was 87mm Hg (range 25-134). The anal sphincter resting pressure was non-obstructive and comparable to healthy normal children. Rectoanal inhibitory reflex was seen in all children excluding diagnosis of Hirschsprung disease.

CONCLUSIONS

Ketamine anesthesia does not affect quantitative or qualitative measurements of autonomic anorectal function and can be used reliably in children who will not tolerate the manometry while awake. Paradoxical contraction of the EAS can only be evaluated in the awake children and should be investigated further as the underlying cause of obstructive defecation in patients with chronic functional constipation and soiling.

Effect of propofol on anal sphincter pressure during anorectal manometry

We evaluated the effect of propofol on resting anal sphincter pressure (RP) during anorectal manometry performed under general anesthesia in 20 children with chronic constipation. After propofol bolus administration, there was a significant decrease in the RP in 95% of children from a mean of 51.5 ± 15.3 to a mean nadir of 21.7 ± 10.5 mmHg (P < 0.001). The new postpropofol RP of 47.0 ± 12.4 mmHg was significantly lower compared with prepropofol RP (P < 0.0001). Propofol should be used with caution as an anesthetic agent for anorectal manometry, given the potential for confounding RP measurements.

Is rectal disimpact always necessary in children with chronic constipation? Evaluation with pelvic ultrasound

PURPOSE

The aim of study was to evaluate if pelvic ultrasound can be useful in managing children with chronic idiopathic constipation.

METHODS

A total of 270 children with idiopathic chronic constipation were enrolled in the study. At baseline and at monthly checkups children were evaluated by clinical score and pelvic ultrasound (US). Patients have been divided in 2 groups, based on pelvic US results: group A with a rectal diameter >3 cm, group B with a rectal diameter <3 cm or rectum not visualized. Both groups were subsequently randomly divided in two subgroups (A1, A2, B1, B2) on the basis of the prescribed treatment (disimpaction for the first week and daily laxative or only daily laxative).

RESULTS

After 1 month of therapy all clinical features improved in group A1 and at pelvic US, rectal size reduced and became not visualized; group A2 showed poor clinical response and transverse diameter of rectum did not modify significantly; B1 and B2 groups showed significant improvement only after 2-3 months.

CONCLUSIONS

Rectal disimpaction is necessary only in presence of MR. Pelvic US is a useful to diagnose MR and to set up the most appropriate treatment protocol for different chronic constipation cases.

Evaluation of outcome of anorectal anomaly in childhood: the role of anorectal manometry and endosonography

The aim of this study was to evaluate role of anorectal manometry (ARM) and anal endosonography (ES) in assessment of the internal anal sphincter (IAS) quality on continence outcome following repair of anorectal anomalies (ARA). We devised a scoring system to evaluate the quality of the IAS based on ARM and ES and correlated the scores with clinical outcome, using a modified Wingfield score (MWS) for faecal continence. We also assessed the implication of megarectum and neuropathy on faecal continence. Of 54 children studied, 34 had high ARA and 20 had low ARA. Children with high ARA had poor sphincters on ES and ARM, and also poor faecal continence compared to those with low ARA. The presence of megarectum and neuropathy was associated with uniformly poor outcome irrespective of the IAS quality. The correlations between MWS on one hand, and ES and ARM scores for IAS on the other hand were weak in the whole study group, ES r = 0.27, P < 0.04, and ARM r = 0.39, P < 0.004. However, the correlations were strong in those who had isolated ARA without megarectum or neuropathy, ES r = 0.51, P < 0.02 and ARM r = 0.55, P < 0.01, respectively. In conclusion, the ARM and ES are valuable in evaluation of continence outcome in children after surgery for ARA and those with good quality IAS had better faecal continence. The IAS is a vital component in functional outcome in absence of neuropathy and megarectum.

Adverse events and behavioral reactions related to ketamine based anesthesia for anorectal manometry in children

BACKGROUND

Pediatric patients undergoing anorectal manometry require ketamine anesthesia as other anesthetic agents affect the anorectal sphincter tone. The aim of this prospective observational audit was to evaluate our practice and report the occurrence of adverse events and behavioral reactions related to the use of ketamine, propofol, and midazolam combinations.

METHODS

Eighty-two consecutive pediatric patients (mean age 8.06 +/- 3.43 years) undergoing anorectal manometry were audited over a 1-year period. After a routine ketamine anesthetic some children were administered midazolam 0.1 mg.kg(-1), at the discretion of the attending anesthetist. Children requiring anal stretch following manometry studies also received propofol 3-5 mg.kg(-1). Intra- and postoperative adverse events, times to spontaneous awakening and discharge from the PACU were noted. Postoperative behavioral reactions were noted in the PACU and at follow-up interviews on the first postoperative day and after a period of 1 month.

RESULTS

Following completion of the audit, all patients fell into one of the four groups depending on the anesthetic agents they received: K (ketamine only, n = 16), KM (ketamine and midazolam, n = 10), KP (ketamine and propofol, n = 27), and KPM (ketamine, propofol, and midazolam, n = 29). There was no difference in the occurrence of behavioral reactions between the four groups at the three stages of follow-up. Overall, five patients reported 'new onset' nightmares that had resolved completely at the 3-month follow-up. The time to spontaneous awakening was shorter for K group (17.8 min +/- 20.2) vs KPM group (61.7 min +/- 24.4; P < 0.001). The times to discharge in minutes was also shorter in the K group (54.5 min, IQR 30-75 vs 90 min IQR 78-120; P < 0.001). Administration of propofol appeared to have an antiemetic effect [odds ratio (OR) 0.1, 95% confidence intervals (CI) 0.02-0.58, P < 0.009] in the recovery unit.

CONCLUSIONS

Our study findings suggest that, besides significantly prolonging time to spontaneous awakening and PACU discharge, neither the use of midazolam, propofol, or combinations is beneficial in preventing the occurrence of behavioral reactions following ketamine anesthesia. Behavioral reactions were common but did not appear to be long-term. Drug combinations with ketamine may have other benefits such as antiemesis.

Peripheral N-methyl-D-aspartate receptors modulate nonadrenergic noncholinergic lower esophageal sphincter relaxation in rabbits

We investigated the role of peripheral N-methyl-D-aspartate (NMDA) receptors in the myenteric plexus in mediating nonadrenergic noncholinergic (NANC) nitrergic relaxation of the lower esophageal sphincter (LES). Isometric contraction of LES strips from Japanese White rabbits was measured. NANC relaxation was induced by KCl (30 mM) in the presence of atropine and guanethidine. The concentration of 3',5'-cyclic guanosine monophosphate (cGMP) was measured using a radioimmunoassay. The muscle strips were exposed to diethyldithiocarbamic acid (DETCA; 3 mM) to inactivate Cu/Zn superoxide dismutase. MK801 (5-methyl-10,11-dihydroxy-5H-dibenzo(a,d)cyclohepten-5,10-imine) inhibited NANC relaxation in a concentration-dependent manner (EC50 = 1.5 x 10(-5) M), accompanied by a decrease in cGMP production. NMDA induced a concentration-dependent relaxation, which was antagonized by MK801. NMDA stimulated cGMP production, which was inhibited by N(G)-nitro-L-arginine. Superoxide dismutase (100 U/mL) shifted the concentration-response relationship of MK801-mediated inhibition of NANC relaxation to the right (EC50 = 3.4 x 10(-5) M), whereas catalase did not. Treatment with DETCA shifted the concentration-response relationships of pyrogallol-, ketamine- and MK801-mediated inhibition of NANC relaxation to the left. These findings suggest that the peripheral NMDA receptors mediate NANC smooth muscle relaxation, and modulate it, in part, through extracellular production of superoxide anions, thus eliminating the relaxant effect of endogenous nitric oxide.

Use of pelvic ultrasound in the diagnosis of megarectum in children with constipation

PURPOSE

It has not been possible so far to differentiate slow transit constipation from functional fecal retention because the existing medical literature lacks data on rectal dimensions for healthy children or children with chronic idiopathic constipation (CIC). We, for the first time, describe the use of pelvic ultrasound (US) to achieve this.

METHODS

A pelvic US was carried out on 82 children with a full or partially full bladder and with no history of bowel problems and on 95 children with CIC. The rectal crescent seen behind the bladder was measured. All children also had documentation of their age, weight, and height.

RESULTS

The median age, weight, and height for the healthy children were comparable with those of the children with CIC. The median rectal crescent size in children with constipation was 3.4 cm (range, 2.10-7.0; IQR, 1.0), as compared with 2.4 cm (range, 1.3-4.2; IQR, 0.72) in the healthy children, and this difference is statistically significant on multiple regressions of log for rectal diameter, adjusted for height, weight, and age (P value< .001).

CONCLUSION

Pelvic US is a quick child-friendly investigation, which can be used to document the presence of megarectum. It should be the first line investigation for all the children with CIC.

Thickening of the internal anal sphincter in idiopathic constipation in children

Thickening of the internal anal sphincter (IAS) is observed in chronic idiopathic constipation (IC) and solitary rectal ulcer syndrome (SRUS), where it has been correlated with the presence and severity of rectal intussusception. Alternatively, thickened IAS may be a feature of the obstructed megarectum in a similar way to the hypertrophy of bladder neck seen in dyssynergic bladders. The aim of this study was to investigate the significance of thickening of the IAS in children with chronic IC and to determine any association between the thickened IAS and anorectal manometry findings and patient's symptoms. A total of 144 children were admitted for investigations and treatment of chronic IC and evaluated prospectively between April 2001 and April 2003. IAS thickness was measured by endosonography using B&K axial endosonic probe type 1850 with a 10-MHz rotating transducer. The thickness of IAS was measured at 3, 6, and 9 o'clock, and the mean value of the three measurements was used for analysis. Functional assessment was done by anorectal manometry pressure studies under ketamine anaesthesia. A validated symptom score (SS) was used to assess the severity of symptoms. The sum of SS ranged between 0 and 65. Spearman's rho two-tailed test was used to correlate the thickness of IAS with patients' symptoms and anorectal manometry findings. Results were expressed as median and range and p-value of less than 0.05 was considered significant. Of 144 children, 84 were boys, median age 8.1 years (range 3.1-15). Soiling was present in 137 (94%) patients, delay in defecation in 132 (91%), and a palpable megarectum on abdominal examination in 117 (80%). The median duration of symptoms and duration of laxative treatment were 4 years (range 0.3-14.5) and 3.3 years (0.2-13.5), respectively. The average severity score for soiling, delay in defecation, palpable megarectum, and the total SS were 8 (range 0-10), 5 (0-10), 2 (0-12), and 33 (11-51), respectively. The median thickness of IAS was 0.9 mm (range 0.3-2.8) and the median resting anal sphincter pressure was 54 mmHg (19-107). The median amplitudes of rectal and anal sphincter contraction were 3 mmHg (1-25) and 9 mmHg (1-35), respectively. The thickness of IAS correlated significantly with total symptom severity score (r=0.31, p=0.0001), soiling score (r=0.28, p=0.001), megarectum score on abdominal palpation (r=0.29, p=0.001), size of megarectum on manometry (r=0.36, p=0.0001), amplitude of rectal contraction (r=0.23, p=0.007), and age of patient (r=0.55, p=0.0001). There was also a significant correlation between the amplitude of rectal and anal sphincter contraction (r=0.32, p=0.0001). There was no correlation between thickness of IAS and resting anal sphincter pressure and amplitude of anal sphincter contraction on anorectal manometry study. A total of 24 children had myectomy of thickened and overactive IAS in addition to the medical treatment of their chronic IC. The histology examination of myectomy specimen with eosin and haematoxylin staining and histochemical acetylcholine esterase staining showed smooth muscle fibres and ganglion cells. Thickening of IAS correlates significantly with duration and severity of symptoms, size of megarectum, and amplitude of rectal contraction. The pathogenesis is secondary to the continuous presence of faeces in the rectum, resulting in chronic abnormal stimulus to the IAS, which leads to hypertrophic changes in the rectum wall and IAS.

Impact of sedation and anesthesia on the rectoanal inhibitory reflex in children

OBJECTIVE

The study objective was to determine whether the rectoanal inhibitory reflex (RAIR) can be elicited during limited anorectal manometry (ARM) performed under general anesthesia (GA).

METHODS

In this retrospective study, patients with intractable constipation who underwent ARM under GA from November 1999 to March 2002 were evaluated. Rectal biopsy specimens were examined for the presence of ganglion cells.

RESULTS

Eighty consecutive patients aged 5 months to 16 years were evaluated. Three patients with Hirschsprung disease were excluded from analysis. Ganglion cells were found in rectal biopsy specimens from 76 patients. RAIR was positive in 69 (90%) and negative in 8 (10%). Forty-five patients received preoperative medications: midazolam (n = 36), midazolam + atropine (n = 3), atropine (n = 1), midazolam + glycopyrrolate (n = 3), and glycopyrrolate (n = 2). Different combinations of general anesthetic medications were used. Ten patients received neuromuscular blockers. The use of preoperative midazolam or atropine did not affect the presence or absence of RAIR; however, the proportion of patients with negative RAIR was higher in those receiving glycopyrrolate (P = 0.007) than in those receiving other medications. There was no significant difference in the effect of the general anesthetic agents or neuromuscular blockers used on the presence or absence of RAIR.

CONCLUSIONS

The rectoanal inhibitory reflex in children can be elicited even when anorectal manometry is performed under general anesthesia. Glycopyrrolate, an anticholinergic, appears to inhibit the demonstration of the RAIR.

Nitroglycerin-induced relaxation of anorectal smooth muscle: evidence for apparent lack of tolerance development in the anaesthetized rat

1. Recent studies indicate that nitroglycerin (NTG) can produce beneficial clinical effects in healing anal fissures through the relaxation of the internal anal sphincter. The in vivo relaxation effects of NTG on the anorectal smooth muscle have not been studied and it is not known whether this tissue may also exhibit pharmacological tolerance toward NTG. 2. We have developed an in vivo procedure in the anaesthetized rat that permits continual monitoring of anorectal pressure after intravenous (i.v.) and intra-rectal application of NTG. The relaxant effects of NTG were quantified via the area-under-the-contraction-waveforms vs time curve (AUEC). 3. AUEC decreased significantly after intra-rectal bolus doses of NTG (5 - 25 microg), in a dose- and time-dependent manner. Sustained relaxation effects on anorectal pressure were also observed after continuous intra-rectal infusions of NTG. 4. Two-hours of i.v. NTG infusion led to a significant reduction in the mean arterial blood pressure (MAP) response toward a i.v. NTG (30 microg) bolus challenge. In contrast, relaxation of the anorectal pressure toward the challenge dose was not altered after NTG infusion. 5. In isolated tissues, cyclic GMP accumulation was significantly decreased after NTG pre-incubation in the rat aorta but not in the rat anorectal smooth muscle and anal sphincter. 6. These results indicate that the relaxation response toward NTG was not diminished in the anorectum under conditions that produced vascular tolerance. Thus, NTG causes significant and sustained in vivo relaxation of anorectal smooth muscle in the anaesthetized rat without evidence of tolerance development.

High and intermediate imperforate anus: results after surgical correction with special respect to internal sphincter function

Embryologically a fistula in an anorectal malformation can be regarded as an ectopic anus. Since 1984 the so-called fistula has been saved and used as the new anal canal in the surgical reconstruction of 48 patients with high or intermediate imperforate anus. A positive rectoanal inhibitory reflex indicating internal sphincter function was recorded in 32 of 43 patients investigated with anorectal manometry. These patients showed significantly better anal continence. It is concluded that there is an internal sphincter "anlage" in the fistulous connection from the bowel to the urogenital tract. Internal sphincter function can be obtained in the majority of the patients, which seems advantageous for their anal function.