- Email: [email protected]
Anal endosonography is useful for postoperative assessment of anorectal malformations
Journal of Pediatric Surgery (2007) 42, 1549–1554
www.elsevier.com/locate/jpedsurg
Anal endosonography is useful for postoperative assessment of anorectal malformations Ragnhild Emblem a,⁎, Lars Mørkrid b , Kristin Bjørnland c a
Service of Pediatric Surgery, Department of Surgery, Rikshospitalet-Radiumhospitalet Medical Center and Faculty of Medicine University of Oslo, 0027 Oslo, Norway b Department of Clinical Chemistry, Rikshospitalet-Radiumhospitalet Medical Center, Oslo, Norway c University of Oslo, Oslo, Norway
Index words: Anorectal malformations; Anal endosonography; Anal manometry
Abstract Aim: This study aimed to develop and evaluate a scoring system for anal endosonography to assess anal canal structures after repair of anorectal malformations (ARM). Methods: Forty patients with ARM aged 16 years (range, 1-22 years) and 20 controls aged 17 years (range, 0.5-20 years) were examined. Anal function was assessed clinically and by anal canal manometry. The anal canal structures were imaged by anal endosonography using a 7.5-MHz transducer. A scoring system was developed to assess the anal sphincters as visualized on the endosonographic images. Results: Continence was significantly correlated to anal canal pressures. The estimated extent of muscle defect (measured in quadrants) and the number of disruptions in the internal and external anal sphincters correlated significantly to the rest and squeeze pressures, respectively. Thus, patients (N4 years) with squeeze pressure of less than 80 cm H2O were characterized by more than 1 disruption in the external anal sphincter ring and 2 or more quadrants with scar tissue. Conclusion: The extent of scar tissue and the number of disruptions in the anal sphincters correlate with anal canal pressures and continence after ARM repair. Anal endosonography may be used to study the results after different surgical techniques and for prognosis on continence in patients with ARM. © 2007 Elsevier Inc. All rights reserved.
Anal endosonography (AES) and lately magnetic resonance imaging (MRI) have been widely used for imaging of the pelvic floor in adults. Both modalities can identify focal defects and scarring in the anal sphincters and thus provide valuable information [1,2]. Anal endosonography and MRI have relative strengths and weaknesses [3]. Compared to MRI, AES is less time-consuming, cheaper, and requires less equipment and human resources. The accuracy of AES in the assessment of the anal sphincters has been validated by
⁎ Corresponding author. Tel.: +47 23 07 00 00; fax: +47 23 07 25 26. E-mail address: [email protected] (R. Emblem). 0022-3468/$ – see front matter © 2007 Elsevier Inc. All rights reserved. doi:10.1016/j.jpedsurg.2007.04.017
comparison with dissected autopsy material and histologic findings after surgery [4,5]. Despite the extensive use of AES in adults, there are few reports of its use in children with anorectal malformations (ARM) [6-8]. The repair of ARM can be performed according to different surgical principles. Until Alberto Pena introduced the posterior sagittal anorectoplasty (PSARP) in 1982, sacroperineal or sacroabdominal pull-through operations were done [9]. When comparing results after these different approaches, data are inconclusive [10,11]. Furthermore, there are no agreed-on methods for assessing functional and anatomical results after corrections for ARM. This is urgently needed because the pull-through procedure has got a
1550
R. Emblem et al.
renaissance because these operations today can be done laparoscopically [12]. Furthermore, limited sagittal anorectoplasty has been suggested to give better functional results than PSARP [13]. To have an objective method for assessing the structure of the anal sphincters after ARM repair is important in evaluating postoperative results, in giving individual patient prognosis on continence, and in guiding treatment. Thus, our aim was to define a scoring system for AES images of the anal sphincters and to explore the relation among AES score, fecal continence, and anal canal pressures.
1. Patients and methods 1.1. Patients Forty patients with mean age of 16 years (range, 1-22 years) operated on for ARM and 20 controls with mean age of 7 years (range, 0.5-20 years) were examined. The age distribution was equal between patients and controls. A total of 25 patients had rectourethral or vestibular fistulas (high malformations), whereas 15 had perineal fistulas (low malformations) corrected. No patients had symptoms of significant neuropathy affecting the bladder.
1.2. Surgical procedures The patients with perineal fistulas had been operated on with a cut-back procedure (12 patients) or a limited PSARP (3 patients). In patients with high malformations, PSARP (9 patients operated on after 1985) or a pull-through procedure (16 patients operated on before 1985) (perineal, sacroperineal, or sacroabdominal pull-through procedure) had been performed.
1.3. Evaluation of fecal continence Fecal continence was graded from 1 to 4 (Table 1). Continence was only evaluated in patients older than 4 years.
1.4. Anal manometry Pressure profiles of the anal sphincters were recorded with a 2-mm diameter microtransducer (Camtec, Oslo, Table 1 Grading of continence for gas and feces in patients operated on for ARM Grade 1 continence
Perfect control of gas, liquids, and solids
Grade 2 continence
Occasionally incontinent for loose stools and/or gas Incontinent for gas and loose stools and sometimes for solid stools Incontinent for gas and loose and solid stools
Grade 3 continence Grade 4 continence
Norway) measuring maximal anal canal rest pressure. Maximal squeeze increments were registered in patients and controls older than 4 years. No sedation was used during these investigations.
1.5. Anal endosonography Imaging of the anal sphincters was performed in all patients and in 6 controls with a 7.5-MHz rotating transducer of 2 to 5 cm focal length (Bruel & Kjaer, Oslo, Norway). The transducer was covered with a hard sonolucent plastic cone (diameter, 17 mm) and filled with degassed water. The procedure was performed with the patient in the left lateral position. Although it has been advocated that the prone position is superior, particularly to examine the anterior part of the external anal sphincter (EAS), we preferred the left lateral because the child/ adolescent then does not see the examining device because this may be frightening. When the child is lying on the side, it is also easier for the parents to distract the child. Serial images were obtained in the upper, middle, and lower levels of the anal canal. Only axial images were recorded. The internal anal sphincter (IAS) and the EAS were assessed in the mid anal canal. Mid anal canal was in the controls defined as the level at which the EAS formed a complete ring anteriorly and in the patients 0.5 to 1.5 cm from the anal verge at the level of the most complete EAS ring. In the anal canal, the IAS is identified as the hypoechogenic zone adjacent to the more heterogeneous hyperechoic subepithelial tissue medially and the hyperechoic heterogeneous EAS laterally. The puborectalis muscle demarcates the proximal part of the normal anal canal and blends into the EAS in the middle part of the canal forming a complete ring anteriorly. By ultrasound the muscle fibers per se are nonreflecting, whereas the fibroelastic elements between the muscle fibers do reflect. The relative hyperechogenicity of the EAS compared with that of the IAS represents the fibroelastic components present in the striated muscle [14,15]. The integrity of the anal sphincters was assessed by applying a modified method described earlier, viewing any sphincter defect in the axial plane to determine the maximal radial extent of the defect [16]. A disruption in the anal sphincters was seen as a relatively hyperechoic area in the IAS and a relatively hypoechoic area in the EAS. Lack of normal sphincter tissue in a section of the circumference of the sphincter, representing 15° or more of the circumference, was defined as a disruption. We counted the number of disruptions in terms of the number of sections lacking normal sphincter tissue. Furthermore, we assessed the extent of muscle defects in the sphincters. If 1 or more sphincter disruptions were detected, the total estimated extent of scars was counted in quadrants. To evaluate the structure of the anal sphincters, both the total number of disruptions in the anal sphincters and the number of scarred quadrants were registered as well as the position of the anal opening in relation to the sphincter complex.
Postoperative assessment of ARM
1551
Table 2 Continence in patients older than 4 years operated on for ARM Grade 1 continence Grade 2 continence Grade 3 continence Grade 4 continence
8 patients 7 had perineal fistula; malformation 8 patients 5 had perineal fistula; malformations 9 patients 1 had perineal fistula; malformations 12 patients 1 had perineal fistula; malformations
1 had high
3 had high
8 had high
11 had high
Grade 1 means perfect control; grade 4 means incontinence for gas, liquid, and solid stools.
1.6. Statistics If not otherwise stated, data are given as means with 95% confidence interval of mean. Although continence was a discrete variable, it was used as a continuous dependent variable in multiple regression analysis because the residuals turned out to be normally distributed. Data were analyzed by analysis of variance, and dependency between sets of variables involving ordered categorical data was expressed through the nonparametric Spearman correlation coefficient. χ2 Test was used for comparing 2 sets of discrete variables. Two-tailed P values of less than .05 were considered significant.
2. Results
Fig. 1 Correlation between continence and rest pressure (A) and correlation between continence and squeeze pressure (B). Pressure values are measured in cm H2O. Mean values and 95% confidence intervals are given.
with vestibular or urethral fistulas than in those with perineal fistulas (Table 3). Continence function was significantly correlated to both anal canal rest (P b .0001) (Fig. 1A) and squeeze pressures (P b .0001) (Fig. 1B).
2.1. Fecal continence Continence was registered in the 37 patients older than 4 years. All of the controls and 8 patients had grade 1 continence. The continence of the patients is outlined in Table 2. No patients were incontinent because of fecal impaction.
2.2. Anal manometry Anal canal pressures were significantly lower (P b .001) in patients than in controls and lower in patients operated on
Table 3 Results of anal canal manometry in patients and controls older than 4 years Category of malformation
Rest pressure, cm H2O (range)
Squeeze pressure, cm H2O (range)
Low malformations High malformations Controls
60 (25-100) 40 (10-90) 85 (30-110)
90 (20-250) 40 (0-200) 150 (75-300)
Perineal fistulas were categorized as low malformations, whereas vestibular and urethral fistulas were evaluated as high malformations.
Fig. 2 Anal endosonography from a 1-year-old boy operated on with PSARP. There are scars anteriorly and posteriorly (between long arrows). In the EAS normal morphology lacks between the 10and 2-o'clock position and between the 4- and 7-o'clock position. There are 2 disruptions in the EAS and 2 quadrants with scars. There are only remnants of IAS, which are marked with short arrows.
1552
Fig. 3 Anal endosonography from a male patient operated on with PSARP with grade 3 continence and reduced anal sphincter function (maximal squeeze pressure, 50 cm H2O; rest pressure, 20 cm H2O). Long white arrows indicate scars anteriorly and posteriorly, and there are 2 disruptions in the EAS. Black arrows indicate the borders of normal EAS. Two quadrants of EAS were estimated to be scarred. White triangles show remnants of IAS.
2.3. Anal endosonography When assessing the position of the anal canal in relation to the sphincter complex, we identified varying degrees of an eccentrically placed or “misplaced” anal canal, leaving more of the sphincter complex at one side compared with the other side of the anal canal. All these patients were operated on before 1985 with pull-through procedures. In all patients operated on with PSARP, 1 posterior and 1 anterior band of scar tissue in the sphincter complex could be identified (Figs. 2 and 3).
R. Emblem et al.
Fig. 5 Squeeze pressure as a function of disruptions in EAS (A) and number of quadrants of the EAS with scars (B). Mean values and 95% confidence intervals are given.
No muscle defects were found in the controls. In the patients, an average of 2.5 quadrants (range, 0-4) of the circumference of the IAS were replaced by scar tissue (Fig. 4). In the EAS the extent of muscle defects reached an average score of 3 quadrants (range, 0-4), and the mean number of disruptions in the EAS was 3 (range, 1-5). The extent of muscle defect in the IAS correlated significantly with continence (P = .0037) and with rest pressure (P b .0001) (Fig. 4). Up to 1 quadrant of scar tissue replacing muscle tissue in the IAS was compatible with normal rest pressure. Both the number of disruptions in the EAS (P b .001) (Fig. 5A) and the extent of EAS defect as measured by quadrants with scars (Fig. 5B) correlated significantly to squeeze pressures (P b .001). In clinical terms, patients older than 4 years with squeeze pressure of less than 80 cm H2O was characterized by more than 1 disruption of the muscular ring and 2 or more quadrants of scar tissue.
3. Discussion
Fig. 4 The number of quadrants in the IAS as a function of rest pressure. Mean values and 95% confidence intervals are given.
In the present study we found that endosonographic appearances of the anal sphincters correlated with functional results after operative treatment of ARM. To the best of our knowledge, this has not been shown earlier. In a small series of 15 patients with intermediate and high
Postoperative assessment of ARM malformations, AES images of the EAS corresponded with electromyographic findings; but the appearance of the IAS did not correspond with anal canal pressures [17]. That AES can be helpful when reoperation is considered for an eccentrically placed anal opening has been reported by us and others [6-8,18]. We applied a scoring system to evaluate the appearance of the IAS and the EAS. Assessing sphincter defects by angle and area to determine radial extent of defect and relation to clinical and manometric features have been reported by others [19,20]. In adult patients with traumatic incontinence, there was a good correlation between anal function and AES features. This is in accordance with our results in patients with ARM in whom the number of disruptions and the area of scar tissue in the sphincter muscles significantly correlated to corresponding anal canal pressure and continence. Most patients in this study reported impaired fecal control and lack of perfect continence correlated to reduced anal canal pressures and scars in the anal sphincters. In the normal anal canal, the rest pressure is mainly attributed to the tonic activity of the IAS. The function of the IAS in patients with ARM has been debated [13,21-23]. It is not unlikely that the actual scars in the IAS identified in our patients may affect the IAS function and fecal control. When focusing on the EAS, 1 disruption of the muscle ring as well as less than 2 quadrants of scar tissue were compatible with acceptable squeeze pressure and good fecal control. This is consistent with the good functional results observed in patients with perineal fistulas. Similarly, 2 distinct disruptions in the EAS, 1 posterior and 1 anterior band, were identified in most patients after PSARP; and this correlated to reduced squeeze pressure and impaired continence. Results after abdominoperineal, sacroabdominoperineal, or sacroperineal pull-through procedures performed in the 1950s to 1980s have been considered inferior to results after PSARP; and for a long period, the PSARP procedure has been the principal surgical method applied in patients with ARM [10,24]. Recently, new techniques with or without laparoscopy and minimal perineal wounds and no dividing of the muscle complex have been introduced [12]. Using MRI in 18 patients, it was recently found that laparoscopic repair of ARM gave superior anatomical results compared with PSARP [23]. In our study there was a significantly impaired EAS function in patients with more than 1 disruption of the muscle and 2 or more quadrants of scar tissue. Whether this means that the surgical procedure should, if possible, be performed by just cutting through the muscle at 1 location or as a pull-through procedure needs to be explored. Some authors suggest that laparoscopically assisted repairs will give better results than those of pull-through operations done decades ago. However, this needs to be confirmed by objective functional parameters as well as imaging modalities such as AES or MRI. Imaging of the anal sphincter integrity should have a central role for postoperative assessment of ARM operations because physical examination is not reliable in the detection of EAS and IAS
1553 defects [25]. Furthermore, anal manometry is not able to distinguish between sphincter dysfunction owing to loss of sphincter integrity and that owing to neuropathy [1]. There are no data showing which imaging modality is superior for evaluating the postoperative results after ARM repair because the experience with both AES and endoanal MRI is limited in this group of patients [6,7,26-29]. Among 17 patients operated on with PSARP, MRI was found to only moderately reflect clinical outcome [30]. In adults, AES is thought to be superior to endoanal MRI to evaluate IAS, whereas both techniques are equivalent for visualization of defects of EAS [3]. There are, however, those who argue that AES is less suitable for assessing EAS atrophy because it cannot distinguish fatty infiltration from normal muscle tissue, and the boundaries of the EAS are harder to determine on AES than on MRI [31]. Because of its simplicity we would argue that AES should be the modality of choice for postoperative assessment in patients with ARM until another modality is proven to be better. However, one must always bear in mind that AES is a single investigation in an armamentarium of investigations and must be interpreted along with the history of the patients and other investigations such as manometry.
References [1] Thakar R, Sultan AH. Anal endosonography and its role in assessing the incontinent patient. Best Practice Res Clin Obstet Gynaecol 2004; 18:157-73. [2] Bartram CI. Functional anorectal imaging. Abdom Imaging 2005;30:195-203. [3] Malouf AJ, Williams AB, Halligan S, et al. Prospective assessment of accuracy of endoanal MR imaging and endosonography in patients with fecal incontinence. Am J Roentgenol 2000;175:741-5. [4] Konerding MA, Dzemali O, Gaumann A, et al. Correlation of endoanal sonography with cross-sectional anatomy of the anal sphincter. Gastrointest Endoscopy 1999;50:804-10. [5] Sultan AH, Nicholls RJ, Kamm MA, et al. Anal endosonography and correlation with in vitro and in vivo anatomy. Br J Surg 1993;80: 508-11. [6] Emblem R, Diseth T, Morkrid L. Anorectal anomalies: anorectal manometric function and anal endosonography in relation to functional outcome. Pediatr Surg Int 1997;12:516-9. [7] Jones NM, Humphreys MS, Goodman TR, et al. The value of anal endosonography compared with magnetic resonance imaging following the repair of anorectal malformations. Pediatr Radiol 2003;33: 183-5. [8] Jones NM, Smilgin-Humphreys M, et al. Paediatric anal endosonography. Pediatr Surg Int 2003;19:703-6. [9] deVries PA, Pena A. Posterior sagittal anorectoplasty. J Pediatr Surg 1982;17:638-43. [10] Rintala RJ, Lindahl HG. Posterior sagittal anorectoplasty is superior to sacroperineal-sacroabdominoperineal pull-through: a long-term follow-up study in boys with high anorectal anomalies. J Pediatr Surg 1999;34:334-7. [11] Pena A, Hong A. Advances in the management of anorectal malformations. Am J Surg 2000;180:370-6. [12] Georgeson KE, Inge TH, Albanese CT. Laparoscopically assisted anorectal pull-through for high imperforate anus—a new technique. J Pediatr Surg 2000;35:927-30.
1554 [13] Chen CC, Lin CL, Lu WT, et al. Anorectal function and endopelvic dissection in patients with repaired imperforate anus. Pediatr Surg Int 1998;13:133-7. [14] Law PJ, Bartram CI. Anal endosonography—technique and normal anatomy. Gastrointest Radiol 1989;14:349-53. [15] Stoker J, Halligan S, Bartram CI. Pelvic floor imaging. Radiology 2001;218:621-41. [16] Gold DM, Bartram CI, Halligan S, et al. Three-dimensional endoanal sonography in assessing anal canal injury. Br J Surg 1999;86:365-70. [17] Fukata R, Iwai N, Yanagihara J, et al. Comparison of anal endosonography with electromyography and manometry in high and intermediate anorectal anomalies. J Pediatr Surg 1997;32: 839-42. [18] Emblem R, Diseth T, Morkrid L, et al. Anal endosonography and physiology in adolescents with corrected low anorectal anomalies. J Pediatr Surg 1994;29:447-51. [19] Williams AB, Malouf AJ, Bartram CI, et al. Assessment of external anal sphincter morphology in idiopathic fecal incontinence with endocoil magnetic resonance imaging. Dig Dis Sci 2001;46:1466-71. [20] Gold DM, Halligan S, Kmiot WA, et al. Intraobserver and interobserver agreement in anal endosonography. Br J Surg 1999;86: 371-5. [21] Lambrecht W, Lierse W. The internal sphincter in anorectal malformations: morphological investigations in neonatal pigs. J Pediatr Surg 1987;22:1160-8. [22] Rintala R, Lindahl H, Marttinen E, et al. Constipation is a major functional complication after internal sphincter-saving posterior sagittal anorectoplasty for high and intermediate anorectal-malformations. J Pediatr Surg 1993;28:1054-8.
R. Emblem et al. [23] Wong KKY, Khong PL, Lin SCL, et al. Post-operative magnetic resonance evaluation of children after laparoscopic anorectoplasty for imperforate anus. Int J Colorectal Dis 2005;20:33-7. [24] Levitt MA, Pena A. Outcomes from the correction of anorectal malformations. Curr Opin Pediatr 2005;17:394-401. [25] Keating JP, Stewart PJ, Eyers AA, et al. Are special investigations of value in the management of patients with fecal incontinence? Dis Colon Rectum 1997;40:896-901. [26] DeSouza NM, Ward HC, Williams AD, et al. Transanal MR imaging after repair of anorectal anomalies in children: appearances in pullthrough versus posterior sagittal reconstructions. Am J Roentgenol 1999;173:723-8. [27] Hettiarachchi M, Garcea G, DeSouza NM, et al. Evaluation of dysfunction following reconstruction of an anorectal anomaly. Pediatr Surg Int 2002;18:405-9. [28] Husberg B, Rosenborg M, Frenckner B. Magnetic resonance imaging of anal sphincters after reconstruction of high or intermediate anorectal anomalies with posterior sagittal anorectoplasy and fistula-preserving technique. J Pediatr Surg 1997;32:1436-42. [29] Tsuji H, Okada A, Nakai H, et al. Follow-up studies of anorectal malformations after posterior sagittal anorectoplasty. J Pediatr Surg 2002;37:1529-33. [30] Schuster T, Lagler F, Pfluger T, et al. A computerized vector manometry and MRI study in children following posterior sagittal anorectoplasty. Pediatr Surg Int 2001;17:48-53. [31] West RL, Dwarkasing S, Briel JW, et al. Can three-dimensional endoanal ultrasonography detect external anal sphincter atrophy? A comparison with endoanal magnetic resonance imaging. Gastroenterology 2005;128:A270.
www.elsevier.com/locate/jpedsurg
Anal endosonography is useful for postoperative assessment of anorectal malformations Ragnhild Emblem a,⁎, Lars Mørkrid b , Kristin Bjørnland c a
Service of Pediatric Surgery, Department of Surgery, Rikshospitalet-Radiumhospitalet Medical Center and Faculty of Medicine University of Oslo, 0027 Oslo, Norway b Department of Clinical Chemistry, Rikshospitalet-Radiumhospitalet Medical Center, Oslo, Norway c University of Oslo, Oslo, Norway
Index words: Anorectal malformations; Anal endosonography; Anal manometry
Abstract Aim: This study aimed to develop and evaluate a scoring system for anal endosonography to assess anal canal structures after repair of anorectal malformations (ARM). Methods: Forty patients with ARM aged 16 years (range, 1-22 years) and 20 controls aged 17 years (range, 0.5-20 years) were examined. Anal function was assessed clinically and by anal canal manometry. The anal canal structures were imaged by anal endosonography using a 7.5-MHz transducer. A scoring system was developed to assess the anal sphincters as visualized on the endosonographic images. Results: Continence was significantly correlated to anal canal pressures. The estimated extent of muscle defect (measured in quadrants) and the number of disruptions in the internal and external anal sphincters correlated significantly to the rest and squeeze pressures, respectively. Thus, patients (N4 years) with squeeze pressure of less than 80 cm H2O were characterized by more than 1 disruption in the external anal sphincter ring and 2 or more quadrants with scar tissue. Conclusion: The extent of scar tissue and the number of disruptions in the anal sphincters correlate with anal canal pressures and continence after ARM repair. Anal endosonography may be used to study the results after different surgical techniques and for prognosis on continence in patients with ARM. © 2007 Elsevier Inc. All rights reserved.
Anal endosonography (AES) and lately magnetic resonance imaging (MRI) have been widely used for imaging of the pelvic floor in adults. Both modalities can identify focal defects and scarring in the anal sphincters and thus provide valuable information [1,2]. Anal endosonography and MRI have relative strengths and weaknesses [3]. Compared to MRI, AES is less time-consuming, cheaper, and requires less equipment and human resources. The accuracy of AES in the assessment of the anal sphincters has been validated by
⁎ Corresponding author. Tel.: +47 23 07 00 00; fax: +47 23 07 25 26. E-mail address: [email protected] (R. Emblem). 0022-3468/$ – see front matter © 2007 Elsevier Inc. All rights reserved. doi:10.1016/j.jpedsurg.2007.04.017
comparison with dissected autopsy material and histologic findings after surgery [4,5]. Despite the extensive use of AES in adults, there are few reports of its use in children with anorectal malformations (ARM) [6-8]. The repair of ARM can be performed according to different surgical principles. Until Alberto Pena introduced the posterior sagittal anorectoplasty (PSARP) in 1982, sacroperineal or sacroabdominal pull-through operations were done [9]. When comparing results after these different approaches, data are inconclusive [10,11]. Furthermore, there are no agreed-on methods for assessing functional and anatomical results after corrections for ARM. This is urgently needed because the pull-through procedure has got a
1550
R. Emblem et al.
renaissance because these operations today can be done laparoscopically [12]. Furthermore, limited sagittal anorectoplasty has been suggested to give better functional results than PSARP [13]. To have an objective method for assessing the structure of the anal sphincters after ARM repair is important in evaluating postoperative results, in giving individual patient prognosis on continence, and in guiding treatment. Thus, our aim was to define a scoring system for AES images of the anal sphincters and to explore the relation among AES score, fecal continence, and anal canal pressures.
1. Patients and methods 1.1. Patients Forty patients with mean age of 16 years (range, 1-22 years) operated on for ARM and 20 controls with mean age of 7 years (range, 0.5-20 years) were examined. The age distribution was equal between patients and controls. A total of 25 patients had rectourethral or vestibular fistulas (high malformations), whereas 15 had perineal fistulas (low malformations) corrected. No patients had symptoms of significant neuropathy affecting the bladder.
1.2. Surgical procedures The patients with perineal fistulas had been operated on with a cut-back procedure (12 patients) or a limited PSARP (3 patients). In patients with high malformations, PSARP (9 patients operated on after 1985) or a pull-through procedure (16 patients operated on before 1985) (perineal, sacroperineal, or sacroabdominal pull-through procedure) had been performed.
1.3. Evaluation of fecal continence Fecal continence was graded from 1 to 4 (Table 1). Continence was only evaluated in patients older than 4 years.
1.4. Anal manometry Pressure profiles of the anal sphincters were recorded with a 2-mm diameter microtransducer (Camtec, Oslo, Table 1 Grading of continence for gas and feces in patients operated on for ARM Grade 1 continence
Perfect control of gas, liquids, and solids
Grade 2 continence
Occasionally incontinent for loose stools and/or gas Incontinent for gas and loose stools and sometimes for solid stools Incontinent for gas and loose and solid stools
Grade 3 continence Grade 4 continence
Norway) measuring maximal anal canal rest pressure. Maximal squeeze increments were registered in patients and controls older than 4 years. No sedation was used during these investigations.
1.5. Anal endosonography Imaging of the anal sphincters was performed in all patients and in 6 controls with a 7.5-MHz rotating transducer of 2 to 5 cm focal length (Bruel & Kjaer, Oslo, Norway). The transducer was covered with a hard sonolucent plastic cone (diameter, 17 mm) and filled with degassed water. The procedure was performed with the patient in the left lateral position. Although it has been advocated that the prone position is superior, particularly to examine the anterior part of the external anal sphincter (EAS), we preferred the left lateral because the child/ adolescent then does not see the examining device because this may be frightening. When the child is lying on the side, it is also easier for the parents to distract the child. Serial images were obtained in the upper, middle, and lower levels of the anal canal. Only axial images were recorded. The internal anal sphincter (IAS) and the EAS were assessed in the mid anal canal. Mid anal canal was in the controls defined as the level at which the EAS formed a complete ring anteriorly and in the patients 0.5 to 1.5 cm from the anal verge at the level of the most complete EAS ring. In the anal canal, the IAS is identified as the hypoechogenic zone adjacent to the more heterogeneous hyperechoic subepithelial tissue medially and the hyperechoic heterogeneous EAS laterally. The puborectalis muscle demarcates the proximal part of the normal anal canal and blends into the EAS in the middle part of the canal forming a complete ring anteriorly. By ultrasound the muscle fibers per se are nonreflecting, whereas the fibroelastic elements between the muscle fibers do reflect. The relative hyperechogenicity of the EAS compared with that of the IAS represents the fibroelastic components present in the striated muscle [14,15]. The integrity of the anal sphincters was assessed by applying a modified method described earlier, viewing any sphincter defect in the axial plane to determine the maximal radial extent of the defect [16]. A disruption in the anal sphincters was seen as a relatively hyperechoic area in the IAS and a relatively hypoechoic area in the EAS. Lack of normal sphincter tissue in a section of the circumference of the sphincter, representing 15° or more of the circumference, was defined as a disruption. We counted the number of disruptions in terms of the number of sections lacking normal sphincter tissue. Furthermore, we assessed the extent of muscle defects in the sphincters. If 1 or more sphincter disruptions were detected, the total estimated extent of scars was counted in quadrants. To evaluate the structure of the anal sphincters, both the total number of disruptions in the anal sphincters and the number of scarred quadrants were registered as well as the position of the anal opening in relation to the sphincter complex.
Postoperative assessment of ARM
1551
Table 2 Continence in patients older than 4 years operated on for ARM Grade 1 continence Grade 2 continence Grade 3 continence Grade 4 continence
8 patients 7 had perineal fistula; malformation 8 patients 5 had perineal fistula; malformations 9 patients 1 had perineal fistula; malformations 12 patients 1 had perineal fistula; malformations
1 had high
3 had high
8 had high
11 had high
Grade 1 means perfect control; grade 4 means incontinence for gas, liquid, and solid stools.
1.6. Statistics If not otherwise stated, data are given as means with 95% confidence interval of mean. Although continence was a discrete variable, it was used as a continuous dependent variable in multiple regression analysis because the residuals turned out to be normally distributed. Data were analyzed by analysis of variance, and dependency between sets of variables involving ordered categorical data was expressed through the nonparametric Spearman correlation coefficient. χ2 Test was used for comparing 2 sets of discrete variables. Two-tailed P values of less than .05 were considered significant.
2. Results
Fig. 1 Correlation between continence and rest pressure (A) and correlation between continence and squeeze pressure (B). Pressure values are measured in cm H2O. Mean values and 95% confidence intervals are given.
with vestibular or urethral fistulas than in those with perineal fistulas (Table 3). Continence function was significantly correlated to both anal canal rest (P b .0001) (Fig. 1A) and squeeze pressures (P b .0001) (Fig. 1B).
2.1. Fecal continence Continence was registered in the 37 patients older than 4 years. All of the controls and 8 patients had grade 1 continence. The continence of the patients is outlined in Table 2. No patients were incontinent because of fecal impaction.
2.2. Anal manometry Anal canal pressures were significantly lower (P b .001) in patients than in controls and lower in patients operated on
Table 3 Results of anal canal manometry in patients and controls older than 4 years Category of malformation
Rest pressure, cm H2O (range)
Squeeze pressure, cm H2O (range)
Low malformations High malformations Controls
60 (25-100) 40 (10-90) 85 (30-110)
90 (20-250) 40 (0-200) 150 (75-300)
Perineal fistulas were categorized as low malformations, whereas vestibular and urethral fistulas were evaluated as high malformations.
Fig. 2 Anal endosonography from a 1-year-old boy operated on with PSARP. There are scars anteriorly and posteriorly (between long arrows). In the EAS normal morphology lacks between the 10and 2-o'clock position and between the 4- and 7-o'clock position. There are 2 disruptions in the EAS and 2 quadrants with scars. There are only remnants of IAS, which are marked with short arrows.
1552
Fig. 3 Anal endosonography from a male patient operated on with PSARP with grade 3 continence and reduced anal sphincter function (maximal squeeze pressure, 50 cm H2O; rest pressure, 20 cm H2O). Long white arrows indicate scars anteriorly and posteriorly, and there are 2 disruptions in the EAS. Black arrows indicate the borders of normal EAS. Two quadrants of EAS were estimated to be scarred. White triangles show remnants of IAS.
2.3. Anal endosonography When assessing the position of the anal canal in relation to the sphincter complex, we identified varying degrees of an eccentrically placed or “misplaced” anal canal, leaving more of the sphincter complex at one side compared with the other side of the anal canal. All these patients were operated on before 1985 with pull-through procedures. In all patients operated on with PSARP, 1 posterior and 1 anterior band of scar tissue in the sphincter complex could be identified (Figs. 2 and 3).
R. Emblem et al.
Fig. 5 Squeeze pressure as a function of disruptions in EAS (A) and number of quadrants of the EAS with scars (B). Mean values and 95% confidence intervals are given.
No muscle defects were found in the controls. In the patients, an average of 2.5 quadrants (range, 0-4) of the circumference of the IAS were replaced by scar tissue (Fig. 4). In the EAS the extent of muscle defects reached an average score of 3 quadrants (range, 0-4), and the mean number of disruptions in the EAS was 3 (range, 1-5). The extent of muscle defect in the IAS correlated significantly with continence (P = .0037) and with rest pressure (P b .0001) (Fig. 4). Up to 1 quadrant of scar tissue replacing muscle tissue in the IAS was compatible with normal rest pressure. Both the number of disruptions in the EAS (P b .001) (Fig. 5A) and the extent of EAS defect as measured by quadrants with scars (Fig. 5B) correlated significantly to squeeze pressures (P b .001). In clinical terms, patients older than 4 years with squeeze pressure of less than 80 cm H2O was characterized by more than 1 disruption of the muscular ring and 2 or more quadrants of scar tissue.
3. Discussion
Fig. 4 The number of quadrants in the IAS as a function of rest pressure. Mean values and 95% confidence intervals are given.
In the present study we found that endosonographic appearances of the anal sphincters correlated with functional results after operative treatment of ARM. To the best of our knowledge, this has not been shown earlier. In a small series of 15 patients with intermediate and high
Postoperative assessment of ARM malformations, AES images of the EAS corresponded with electromyographic findings; but the appearance of the IAS did not correspond with anal canal pressures [17]. That AES can be helpful when reoperation is considered for an eccentrically placed anal opening has been reported by us and others [6-8,18]. We applied a scoring system to evaluate the appearance of the IAS and the EAS. Assessing sphincter defects by angle and area to determine radial extent of defect and relation to clinical and manometric features have been reported by others [19,20]. In adult patients with traumatic incontinence, there was a good correlation between anal function and AES features. This is in accordance with our results in patients with ARM in whom the number of disruptions and the area of scar tissue in the sphincter muscles significantly correlated to corresponding anal canal pressure and continence. Most patients in this study reported impaired fecal control and lack of perfect continence correlated to reduced anal canal pressures and scars in the anal sphincters. In the normal anal canal, the rest pressure is mainly attributed to the tonic activity of the IAS. The function of the IAS in patients with ARM has been debated [13,21-23]. It is not unlikely that the actual scars in the IAS identified in our patients may affect the IAS function and fecal control. When focusing on the EAS, 1 disruption of the muscle ring as well as less than 2 quadrants of scar tissue were compatible with acceptable squeeze pressure and good fecal control. This is consistent with the good functional results observed in patients with perineal fistulas. Similarly, 2 distinct disruptions in the EAS, 1 posterior and 1 anterior band, were identified in most patients after PSARP; and this correlated to reduced squeeze pressure and impaired continence. Results after abdominoperineal, sacroabdominoperineal, or sacroperineal pull-through procedures performed in the 1950s to 1980s have been considered inferior to results after PSARP; and for a long period, the PSARP procedure has been the principal surgical method applied in patients with ARM [10,24]. Recently, new techniques with or without laparoscopy and minimal perineal wounds and no dividing of the muscle complex have been introduced [12]. Using MRI in 18 patients, it was recently found that laparoscopic repair of ARM gave superior anatomical results compared with PSARP [23]. In our study there was a significantly impaired EAS function in patients with more than 1 disruption of the muscle and 2 or more quadrants of scar tissue. Whether this means that the surgical procedure should, if possible, be performed by just cutting through the muscle at 1 location or as a pull-through procedure needs to be explored. Some authors suggest that laparoscopically assisted repairs will give better results than those of pull-through operations done decades ago. However, this needs to be confirmed by objective functional parameters as well as imaging modalities such as AES or MRI. Imaging of the anal sphincter integrity should have a central role for postoperative assessment of ARM operations because physical examination is not reliable in the detection of EAS and IAS
1553 defects [25]. Furthermore, anal manometry is not able to distinguish between sphincter dysfunction owing to loss of sphincter integrity and that owing to neuropathy [1]. There are no data showing which imaging modality is superior for evaluating the postoperative results after ARM repair because the experience with both AES and endoanal MRI is limited in this group of patients [6,7,26-29]. Among 17 patients operated on with PSARP, MRI was found to only moderately reflect clinical outcome [30]. In adults, AES is thought to be superior to endoanal MRI to evaluate IAS, whereas both techniques are equivalent for visualization of defects of EAS [3]. There are, however, those who argue that AES is less suitable for assessing EAS atrophy because it cannot distinguish fatty infiltration from normal muscle tissue, and the boundaries of the EAS are harder to determine on AES than on MRI [31]. Because of its simplicity we would argue that AES should be the modality of choice for postoperative assessment in patients with ARM until another modality is proven to be better. However, one must always bear in mind that AES is a single investigation in an armamentarium of investigations and must be interpreted along with the history of the patients and other investigations such as manometry.
References [1] Thakar R, Sultan AH. Anal endosonography and its role in assessing the incontinent patient. Best Practice Res Clin Obstet Gynaecol 2004; 18:157-73. [2] Bartram CI. Functional anorectal imaging. Abdom Imaging 2005;30:195-203. [3] Malouf AJ, Williams AB, Halligan S, et al. Prospective assessment of accuracy of endoanal MR imaging and endosonography in patients with fecal incontinence. Am J Roentgenol 2000;175:741-5. [4] Konerding MA, Dzemali O, Gaumann A, et al. Correlation of endoanal sonography with cross-sectional anatomy of the anal sphincter. Gastrointest Endoscopy 1999;50:804-10. [5] Sultan AH, Nicholls RJ, Kamm MA, et al. Anal endosonography and correlation with in vitro and in vivo anatomy. Br J Surg 1993;80: 508-11. [6] Emblem R, Diseth T, Morkrid L. Anorectal anomalies: anorectal manometric function and anal endosonography in relation to functional outcome. Pediatr Surg Int 1997;12:516-9. [7] Jones NM, Humphreys MS, Goodman TR, et al. The value of anal endosonography compared with magnetic resonance imaging following the repair of anorectal malformations. Pediatr Radiol 2003;33: 183-5. [8] Jones NM, Smilgin-Humphreys M, et al. Paediatric anal endosonography. Pediatr Surg Int 2003;19:703-6. [9] deVries PA, Pena A. Posterior sagittal anorectoplasty. J Pediatr Surg 1982;17:638-43. [10] Rintala RJ, Lindahl HG. Posterior sagittal anorectoplasty is superior to sacroperineal-sacroabdominoperineal pull-through: a long-term follow-up study in boys with high anorectal anomalies. J Pediatr Surg 1999;34:334-7. [11] Pena A, Hong A. Advances in the management of anorectal malformations. Am J Surg 2000;180:370-6. [12] Georgeson KE, Inge TH, Albanese CT. Laparoscopically assisted anorectal pull-through for high imperforate anus—a new technique. J Pediatr Surg 2000;35:927-30.
1554 [13] Chen CC, Lin CL, Lu WT, et al. Anorectal function and endopelvic dissection in patients with repaired imperforate anus. Pediatr Surg Int 1998;13:133-7. [14] Law PJ, Bartram CI. Anal endosonography—technique and normal anatomy. Gastrointest Radiol 1989;14:349-53. [15] Stoker J, Halligan S, Bartram CI. Pelvic floor imaging. Radiology 2001;218:621-41. [16] Gold DM, Bartram CI, Halligan S, et al. Three-dimensional endoanal sonography in assessing anal canal injury. Br J Surg 1999;86:365-70. [17] Fukata R, Iwai N, Yanagihara J, et al. Comparison of anal endosonography with electromyography and manometry in high and intermediate anorectal anomalies. J Pediatr Surg 1997;32: 839-42. [18] Emblem R, Diseth T, Morkrid L, et al. Anal endosonography and physiology in adolescents with corrected low anorectal anomalies. J Pediatr Surg 1994;29:447-51. [19] Williams AB, Malouf AJ, Bartram CI, et al. Assessment of external anal sphincter morphology in idiopathic fecal incontinence with endocoil magnetic resonance imaging. Dig Dis Sci 2001;46:1466-71. [20] Gold DM, Halligan S, Kmiot WA, et al. Intraobserver and interobserver agreement in anal endosonography. Br J Surg 1999;86: 371-5. [21] Lambrecht W, Lierse W. The internal sphincter in anorectal malformations: morphological investigations in neonatal pigs. J Pediatr Surg 1987;22:1160-8. [22] Rintala R, Lindahl H, Marttinen E, et al. Constipation is a major functional complication after internal sphincter-saving posterior sagittal anorectoplasty for high and intermediate anorectal-malformations. J Pediatr Surg 1993;28:1054-8.
R. Emblem et al. [23] Wong KKY, Khong PL, Lin SCL, et al. Post-operative magnetic resonance evaluation of children after laparoscopic anorectoplasty for imperforate anus. Int J Colorectal Dis 2005;20:33-7. [24] Levitt MA, Pena A. Outcomes from the correction of anorectal malformations. Curr Opin Pediatr 2005;17:394-401. [25] Keating JP, Stewart PJ, Eyers AA, et al. Are special investigations of value in the management of patients with fecal incontinence? Dis Colon Rectum 1997;40:896-901. [26] DeSouza NM, Ward HC, Williams AD, et al. Transanal MR imaging after repair of anorectal anomalies in children: appearances in pullthrough versus posterior sagittal reconstructions. Am J Roentgenol 1999;173:723-8. [27] Hettiarachchi M, Garcea G, DeSouza NM, et al. Evaluation of dysfunction following reconstruction of an anorectal anomaly. Pediatr Surg Int 2002;18:405-9. [28] Husberg B, Rosenborg M, Frenckner B. Magnetic resonance imaging of anal sphincters after reconstruction of high or intermediate anorectal anomalies with posterior sagittal anorectoplasy and fistula-preserving technique. J Pediatr Surg 1997;32:1436-42. [29] Tsuji H, Okada A, Nakai H, et al. Follow-up studies of anorectal malformations after posterior sagittal anorectoplasty. J Pediatr Surg 2002;37:1529-33. [30] Schuster T, Lagler F, Pfluger T, et al. A computerized vector manometry and MRI study in children following posterior sagittal anorectoplasty. Pediatr Surg Int 2001;17:48-53. [31] West RL, Dwarkasing S, Briel JW, et al. Can three-dimensional endoanal ultrasonography detect external anal sphincter atrophy? A comparison with endoanal magnetic resonance imaging. Gastroenterology 2005;128:A270.