Augmented-pressure distal colostogram: the most important diagnostic tool for planning definitive surgical repair of anorectal malformations in boys

[Developmental disorders of the gastrointestinal tract]

BACKGROUND

Developmental disorders of the gastrointestinal tract comprise a broad spectrum of congenital malformations of different etiologies and locations from the mouth to the anus.

METHODS

The authors present the most important malformations of the gastrointestinal tract on the basis of basic and current reviews.

RESULTS

Gastrointestinal developmental disorders occur both sporadically and in connection with malformation syndromes. Symptoms are highly variable and range from postnatal emergencies to asymptomatic abnormalities, which may be incidental radiological findings. Prenatal ultrasound examinations can often identify gastrointestinal developmental disorders at an early stage. Here, fetal magnetic resonance imaging can be a useful addition to the diagnostic process. In the first few days of life, simple X‑ray overview images, supplemented by images after the administration of contrast medium, are often sufficient.

CONCLUSION

Many patients with a malformation of the gastrointestinal tract require lifelong medical care, so that not only pediatric radiologists need specific knowledge about this group of diseases.

The comparison of magnetic resonance and fluoroscopic imaging options in the preoperative assessment of boys with anorectal malformations and a colostomy

BACKGROUND

In recent decades, magnetic resonance imaging (MRI) has gained prominence as a standard diagnostic method for preoperative assessment in patients with anorectal malformations and a colostomy, with the potential to replace the classic fluoroscopic distal pressure colostogram (FDPC). Three MRI techniques are available: MRI-distal pressure colostogram with gadolinium (MRI-DPCG) or saline (MRI-DPCS) instillation into the colostomy and native MRI without colostomy instillation.

OBJECTIVE

To evaluate and compare the diagnostic accuracy of MRI (native MRI, MRI-DPCG and MRI-DPCS) in the preoperative workup of boys with an anorectal malformation and a colostomy and to compare it to FDPC.

MATERIALS AND METHODS

Sixty-two boys with preoperative MRI using one of the three approaches and 43 with FDPC met the inclusion criteria for this retrospective study. The presence and localization of rectal fistulas according to the Krickenbeck classification were evaluated and compared with intraoperative findings.

RESULTS

The accuracy of fistula detection for MRI in general (regardless of the technique), MRI-DPCS, MRI-DPCG, native MRI and FDPC was 95% (59/62, P<0.001), 100% (12/12, P=0.03), 100% (30/30, P<0.001), 85% (17/20, P=0.41) and 72% (31/43, P=0.82), respectively. The accuracy of describing fistula type in patients with a correctly detected fistula using these methods was 96% (45/47, P<0.001), 100% (9/9, P<0.001), 100% (23/23, P<0.001), 87% (13/15, P<0.001) and 67% (13/21, P=0.002), respectively.

CONCLUSION

MRI is a reliable method for detecting and classifying fistulas in boys with an anorectal malformation and a colostomy and can be considered the modality of first choice for preoperative workup.

Preoperative fistula diagnostics in male anorectal malformations after colostomy: a single-center experience

BACKGROUND

Accurate preoperative fistula diagnostics in male anorectal malformations (ARM) after colostomy are of great significance. We reviewed our institutional experiences and explored methods for improving the preoperative diagnostic accuracy of fistulas in males with ARMs after colostomy.

METHODS

A retrospective analysis was performed on males with ARMs after colostomy admitted to our hospital from January 2015 to June 2022. All patients underwent magnetic resonance imaging (MRI) and high-pressure colostogram (HPC) before anorectal reconstruction. Patients with no fistula as diagnosed by both modalities underwent a voiding cystourethrogram (VCUG). General information, imaging results and surgical results were recorded.

RESULTS

Sixty-nine males with ARMs after colostomy were included. Age at the time of examination was 52 ~ 213 days, and the median age was 89 days. The Krickenbeck classification according to surgical results included rectovesical fistula (n = 19), rectoprostatic fistula (n = 24), rectobulbar fistula (n = 19) and no fistula (n = 7). There was no significant difference in the diagnostic accuracy between MRI and HPC for different types of ARMs. For determining the location of the fistula, compared to surgery, HPC (76.8%, 53/69) performed significantly better than MRI (60.9%, 42/69) (p = 0.043). Sixteen patients diagnosed as having no fistula by MRI or HPC underwent a VCUG, and in 14 patients, the results were comfirmed. However, there were 2 cases of rectoprostatic fistula that were not correctly diagnosed.

CONCLUSION

High-pressure colostogram has greater accuracy than MRI in the diagnosis of fistula type in males with ARMs after colostomy. For patients diagnosed with no fistula by both methods, VCUG reduces the risk of false-negative exclusion, and rectoprostatic fistula should be considered during the operation.

Labeling male anorectal malformations: objective evaluation of radiologic imaging before surgery

Purpose

Prone cross-table lateral x-ray (CTLxR) and colostogram aid surgical planning for anorectal malformations (ARMs) without perineal fistulas. We suggest objective imaging tools to classify ARMs.

Methods

Three observers prospectively evaluated CTLxR and colostograms of male ARM patients (2012-2022) without perineal fistulas. The level of the rectal pouch was estimated with pubococcygeal (PC) and ischiatic (I) lines. On CTLxR, we described the "pigeon sign", defined as the rectal pouch ending with a beak-like image, suspicious for a rectourinary fistula. ARM was defined as rectobulbar when the rectal pouch was below the I line, rectoprostatic when between PC and I lines, and rectovesical when above the PC line. Concordance was assessed with Fleiss' kappa. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the "pigeon sign" were calculated.

Results

Thirteen patients were included in this study. The interobserver agreement on CTLxR was 69.2% (k = 0.54) on pouch ending, 84.6% (k = 0.69) on the "pigeon sign", and 76.9% (k = 0.69) on diagnosis; concordance between observers and intraoperative diagnosis was 66.6% (k = 0.56). The "pigeon sign" had 75% sensitivity, 100% specificity, 100% PPV, and 50% NPV. The interobserver agreement on colostograms was 84.6% (k = 0.77) on pouch ending and 89.7% (k = 0.86) on diagnosis; concordance between observers and intraoperative diagnosis was 92.3% (k = 0.90).

Conclusion

PC and I lines and the "pigeon sign" are useful tools in examining CTLxR and colostograms. Adequate CTLxR interpretation may modify surgical strategy.

High-Resolution Transperineal Ultrasound in Anorectal Malformations—Can We Replace the Distal Colostogram?

Introduction  Anorectal malformations (ARM) affect 1 in 5,000 newborns with a wide range of defects. In the absence of a visible fistula, the diagnosis and classification of ARM require an augmented pressure distal colostogram. This procedure can be done after a diverting colostomy has been performed and implies exposing the child to radiation. We hypothesized that high-resolution transperineal ultrasound could correctly diagnose the type of ARM, thus sparing radiation exposure.

Case Description  Four full-term male newborns with ARM and no visible anal opening were referred to our center for further management. A diverting descendostomy was performed in the first 48 hours of life in all cases. Prior to the reconstructive surgery, we performed a high-resolution transperineal ultrasound with 3D tomographic reconstruction of the perineal region to assess the urethra, the rectum, and a possible fistula. Findings were compared with a conventional augmented pressure distal colostogram. The image acquisition was fast and did not cause any additional distress to the children.

Conclusion  In all cases the results of the distal colostogram nicely correlated with the high-resolution transperineal ultrasound with 3D tomographic reconstruction. In the future, we envision a time when it can potentially replace the distal colostogram in preoperative assessment of ARM with no distress and exposure to radiation.

Reoperative surgery in anorectal malformation patients

Currently accepted primary repair of congenital anorectal malformations (ARMs) includes a posterior sagittal incision, which allows for optimal visualization and identification of important pelvic structures and anatomical features. Reconstructive surgery involves meticulous dissection and separation of pelvic structures, and careful reconstruction can result in good functional outcomes for many patients, who live without ongoing sequelae from their malformation. However, some patients may require reoperative procedures for anatomic or functional reasons. Males and females present with slightly different symptoms and should be approached differently. Males are most likely to require reoperations for anorectal or urethral pathologies, but the urinary system is often spared in females-they instead must contend with Mullerian duct anomalies, of which there are many varieties. Depending on the original malformation and severity of symptoms, redo surgery may be needed to optimize function and quality of life. Surgical management with reoperative surgery in ARMs ranges from straightforward to complex, depending on the issue. One must weigh the risks of reoperative surgery and potentially creating more scarring against the need for a better anatomical and functional outcome. Current management trends and practice patterns with regards to reoperative surgery in ARM patients are not widely studied or standardized but we provide an overview of the more common pathologies, preoperative evaluation and workup required to identify the issues, and options for reoperative repair in these patients.

Accuracy of pre-operative fistula diagnostics in anorectal malformations

Background

Surgical safety during posterior sagittal anorectal plasty (PSARP) for anorectal malformations (ARM) depends on accurate pre-operative fistula localization. This study aimed to evaluate accuracy of pre-operative fistula diagnostics.

Methods

Ethical approval was obtained. Diagnostic accuracy of pre-PSARP symptoms (stool in urine, urine in passive ostomy, urinary tract infection) and examination modalities (voiding cystourethrogram (VCUG), high-pressure colostogram, cystoscopy and ostomy endoscopy) were compared to final intra-operative ARM-type classification in all male neonates born with ARM without a perineal fistula treated at a tertiary pediatric surgery center during 2001–2020.

Results

The 38 included neonates underwent reconstruction surgery through PSARP with diverted ostomy. Thirty-one (82%) had a recto-urinary tract fistula and seven (18%) no fistula. Ostomy endoscopy yielded the highest diagnostic accuracy for fistula presence (22 correctly classified/24 examined cases; 92%), and pre-operative symptoms the lowest (21/38; 55%). For pre-operative fistula level determination, cystoscopy yielded the highest diagnostic accuracy (14/20; 70%), followed by colostogram (23/35; 66%), and VCUG (21/36; 58%). No modality proved to be statistically superior to any other.

Conclusions

Ostomy endoscopy has the highest diagnostic accuracy for fistula presence, and cystoscopy and high-pressure colostogram for fistula level determination. Correct pre-operative ARM-typing reached a maximum of 60–70%.

Anorectal malformation with long perineal fistula: one of a special type

The anorectal malformation with long perineal fistula is a rare anomaly in the spectrum of anorectal malformations. Aim of the study is to describe the series of patients with anorectal malformation with long perineal fistula and compare the outcome with patient with standard perineal fistula. From March 2012 to January 2019, 7 patients who suffered from anorectal malformation with long perineal fistula were retrospectively reviewed. Three were operated on primarily by our department, and 4 cases were re-operated after a perineal anoplasty repair performed elsewhere. Four were operated by laparoscopy assisted anorectoplasty, and 3 cases were repaired by posterior sagittal anorectoplasty. The follow-up outcomes were compared with 71 cases of normal perineal fistula (NPF) in the same period. 7 cases have been followed up for 0.5–4 years (M = 2.57 ± 1.26) after definitive surgery. Their bowel function score was lower than normal perineal fistula (SPF = 12, range: 5–18; NPF = 18.5, range: 18–20). Four cases underwent anorectomanometry. The incidence of rectoanal inhibitory reflex was lower in the special type group. (p = 0.14). Three cases of contrast enema using barium: 2 cases of colorectal dilatation and thickening changes, 1 case showed no obvious abnormalities. Anorectal perineal fistula should be examined by distal colostogram at preoperation. This should be altered in: When suspecting a case of anorectal malformation type long perineal fistula a preoperative contrast enema could give insight of the anatomy befor performing a anoplasty.

Contrast enhanced colostography: New applications in preoperative evaluation of anorectal malformations

INTRODUCTION

Understanding details of anatomic relationships between the colon and surrounding structures is a critical piece of preoperative planning prior to surgical repair of anorectal malformations (ARMs). Traditional imaging techniques involve ionizing radiation, distention of the rectum with supraphysiologic intraluminal pressures, and sometimes require sedation. Recent developments in the field of contrast agents have allowed the emergence of an ultrasound-based technique that can avoid these requirements while continuing to provide high resolution structural information in three dimensions.

METHODS

Fourteen children (13 male, 1 female, age 1-11 months) with ARMs underwent contrast enhanced colostography (ceCS) in addition to traditional preoperative imaging techniques to delineate anatomic relationships of pelvic structures.

RESULTS

ceCS and traditional imaging yielded concordant anatomic information, including structural relationships and fistulous connections, in 10/14 patients (71%). ceCS detected fistulous connection in 2/13 patients (15%) that were not seen by traditional imaging. Ultrasonography failed to detect the fistulous connection in one patient.

CONCLUSIONS

ceCS is a safe, effective and flexible method for defining important structural information in ARM patients. When compared with traditional methods, it provided equivalent or superior results 93% of the time and bears consideration as a standard tool in preoperative planning for this population.

TYPE OF STUDY

Retrospective Comparative Study.

LEVEL OF EVIDENCE

Level III.

Lasting impact on children with an anorectal malformations with proper surgical preparation, respect for anatomic principles, and precise surgical management

Optimal outcomes in the management of children with Anorectal Malformation (ARM) require careful surgical preparation and detailed understanding of the anatomic principles and operative setup. A clear understanding of operative anatomy and surgical principals guides decision making. Adherence to the principles of ARM repair, as well as the application of operative and imaging adjuncts, will yield the safest and most successful approach to ARM. In this review, we detail the surgical preparation, anatomic principles, and surgical management issues unique to ARM.

Image of the Month: High Pressure Distal Colostogram in a Patient with an Anorectal Malformation

An adequately performed high pressure distal colostogram is crucial to plan surgery in male patients born with anorectal malformations. We present two male patients that underwent a divided sigmoid colostomy with distal mucus fistula in the neonatal period and at 6 months of age underwent a high pressure distal colostogram. In the discussion, we will give some tricks beyond the known rules: how to correctly interpret a high pressure distal colostogram, how to identify the level of a recto-urinary fistula, and how to accurately plan the surgical approach.

Image of the Month: How to Select the Ideal Surgical Approach in Male Anorectal Malformation with No Visible Fistula

We present a case of a 6-month-old male infant with an anorectal malformation (ARM) who underwent colostomy as a newborn, and now presents for definitive repair. A colostogram is shown to identify the malformation and to help plan for the ideal surgical approach. The case is presented with a focus on surgical strategies for management of ARM in the male infant, with questions for the readers posed in a quiz format.

Inter- and Intraobserver Variation in the Assessment of Preoperative Colostograms in Male Anorectal Malformations: An ARM-Net Consortium Survey

Aim: Male patients with anorectal malformations (ARM) are classified according to presence and level of the recto-urinary fistula. This is traditionally established by a preoperative high-pressure distal colostogram that may be variably interpreted by different surgeons. The aim of this study was to evaluate the inter- and intraobserver variation in the assessment by pediatric surgeons of preoperative colostograms with respect to the level of the recto-urinary fistula. Materials and Methods: Sixteen pediatric surgeons from 14 European centers belonging to the ARM-Net Consortium twice scored 130 images of distal colostograms taken in sagittal projection at a median age of 66 days of life (range: 4-1,106 days). Surgeons were asked to classify the fistula in bulbar, prostatic, bladder-neck, no fistula, and "unclear anatomy" example. Their assessments were compared with the intraoperative findings (kappa) for two scoring rounds with an interval of 6 months (intraobserver variation). Agreement among the surgeons' scores (interobserver variation) was also calculated using Krippendorff's alpha. A kappa over 0.75 is considered excellent, between 0.40 and 0.75 fair to good, and below 0.40 poor. Surgeons were asked to score the images in "poor" and "good" quality and to provide their years of experience in ARM treatment. Results: Agreement between the image-based rating of surgeons and the intraoperative findings ranges from 0.06 to 0.45 (mean 0.31). Interobserver variation is higher (Krippendorff's alpha between 0.40 and 0.45). Years of experience in ARM treatment does not seem to influence the scoring. The mean intraobserver variation between the two rounds is 0.64. Overall, the quality of the images is considered poor. Images categorized as having a good quality result in a statistically significant higher kappa (mean: 0.36 and 0.37 in the first and second round, respectively) than in the group of bad-quality images (mean: 0.25 and 0.23, respectively). Conclusions: There is poor agreement among experienced pediatric colorectal surgeons on preoperative colostograms. Techniques and analyses of images need to be improved in order to generate a homogeneous series of patients and make comparison of outcomes reliable.

Identification of an occult recto-prostatic fistula with cystoscopy-assisted air colostogram

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High anorectal malformations (ARM) are associated with rectourinary fistulae.

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Augmented-pressure colostogram is the gold standard in diagnosing recto-urinary fistulae in cases of ARM.

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Cystoscopic assisted air colostogram can be used as an adjunctive diagnostic to augmented-pressure colostogram.

Introduction

Anorectal malformations (ARM) in newborns classically present with the absence of a normal anus or an abnormally located anus. In a male infant with a high ARM, an initial diverting colostomy is later followed by a definitive posterior sagittal anorectoplasty (PSARP). Prior to definitive surgery an augmented-pressure colostogram is performed to identify the location of the fistula between the rectum and urogenital tract. However, on occasion, the augmented-pressure colostogram fails to identify the location of the fistula tract. We present a case of ARM where augmented-pressure colostogram failed to identify a fistula tract, thus requiring an alternative diagnostic approach.

Presentation of case

A newborn male presented with a high anorectal malformation and suspected rectourinary fistula on initial augmented-pressure colostogram. The patient ultimately underwent a laparoscopic assisted PSARP after cystoscopy with air colostogram identified the exact location of the fistulous connection in the prostatic urethra.

Discussion

Augmented-pressure colostogram remains the gold standard in diagnosing rectourinary fistulae in cases of ARM. However, a number of alternative and adjunctive techniques have been proposed in recent years. We provide a brief review of the literature in addition to a case presentation highlighting the potential benefits of pre-operative cystoscopy-assisted air colostogram in male patients with ARM.

Conclusion

Cystoscopy-assisted air colostogram via a distal mucous fistula can be utilized as an alternative diagnostic modality, especially when the augmented-pressure distal colostogram fails to identify rectourinary fistulae in high anorectal malformations.

Contrast-Enhanced Colosonography for the Evaluation of Children With an Imperforate Anus

This case series describes a novel method for showing the preoperative anatomy of children with anorectal malformations using ultrasound contrast, which we have termed "contrast-enhanced colosonography (ceCS)." Six patients with anorectal malformations without a perineal fistula were studied both by fluoroscopic distal colostography and ceCS, and their results were confirmed surgically. Contrast-enhanced CS precisely showed the complex anatomic relationships in all cases. Compared to traditional fluoroscopic studies, ceCS has the benefit of no associated ionizing radiation and thus is safer for children.

A call to ARMs: Accurate identification of the anatomy of the rectourethral fistula in anorectal malformations

Recto-urethral fistulae are the most common finding in males born with an anorectal malformation (ARM). A high pressure distal colostogram is an important tool in visualizing the fistula, although the precise level at which the fistula communicates with the urethra may be difficult to interpret and is not reported in a uniform manner. This anatomy affects the surgical plan; determining the likelihood that the rectum is reachable via a posterior sagittal incision or better approached through the abdomen via laparoscopy or laparotomy helps counsel families and stratifies diagnoses for outcomes work. Herein we present a figure used at our Center to assist with correlating findings on the distal colostogram with the anatomic level of the recto-urethral fistula in males with anorectal malformations.

Error traps and culture of safety in anorectal malformations

INTRODUCTION

Attempting to decrease iatrogenic injuries and preventable harm, safety initiatives have become a priority in surgery. For adult hepatobiliary surgery, it has become common to study and consider "error traps" or common pitfalls that exist for laparoscopic cholecystectomy.^1-4 Extending this work to children, we have attempted to apply some of these initiatives by identifying error traps common to the care of patients born with anorectal malformations (ARM).

METHODS

Five error traps were identified based on a retrospective analysis of operative records and radiographic studies from 398 re operative ARM cases performed by the authors. Once identified, the authors constructed a specific safety plan for each trap to promote a culture that will hopefully prevent ARM iatrogenic injuries.

RESULTS

The identified error traps are: 1) creation of a colostomy too distal in the sigmoid colon, 2) inaccurate distal colostogram and definition of the patient's preoperative anatomy 3) absence of a Foley catheter during the repair of an ARM in males and the hazards of separating the anterior rectal wall from the genito-urinary (GU) tract 4) mismanagement of a post-operative anal stricture following an ARM reconstructive procedure 5) limited or unstructured follow up of these patients. For each of the five traps the authors present suggestions for their avoidance.

CONCLUSION

The repair on an anorectal malformation is an elective procedure and while not completely avoidable, there should be little tolerance for iatrogenic injury and preventable harm. A culture of safety should be followed, beginning with a recognition of the common error traps associated with ARM procedures.

Comparison of diagnostic accuracy for fistulae at ultrasound and voiding cystourethrogram in neonates with anorectal malformation

BACKGROUND

Recently, it has been reported that anorectal malformation with rectourethral fistula in male neonates can be managed by primary neonatal reconstruction without colostomy. To prevent urethral injury during anorectoplasty, the fistula's location is important. To date, the use of voiding cystourethrograms to determine the presence and location of fistulas in neonates with anorectal malformations has not been studied.

OBJECTIVE

To compare the accuracy of ultrasound (US) and voiding cystourethrogram for determining the presence and location of fistulas in neonates with anorectal malformation.

MATERIALS AND METHODS

We included 21 male neonates with anorectal malformation with rectourethral fistula (n=16), rectovesical fistula (n=1) or no fistula (n=4) who underwent US and voiding cystourethrogram preoperatively on the day of surgery. Fistula imaging was classified into three grades (0-2), and grades 1-2 were considered fistula positive. We compared the imaging-based location of the fistula with surgical findings.

RESULTS

US performed significantly better than voiding cystourethrogram for determining the presence of fistulas (area under the receiver operating characteristic curve, 0.90 vs. 0.71, respectively; P=0.044) (diagnostic accuracy 85.7%, 95% confidence interval [95% CI] 63.7-97.0% and 52.4%, 95% CI 29.8-74.3%, respectively). In cases with fistulas detected by either modality, the accuracy of locating the fistula by US was 50.0% (95% CI 24.7-75.3%) and by voiding cystourethrogram was 100% (95% CI: 59.0-100%).

CONCLUSION

US accurately detected, but did not accurately locate, fistulas in neonates with anorectal malformation. When planning primary neonatal reconstruction of anorectal malformation without colostomy, voiding cystourethrogram could provide additional information about fistula location.

Comparison Between the Pouch-Perineum Distance in Neonates With a Low-Type Anorectal Malformation With and Without an Opened Fistula: Pitfall of Measuring the Pouch-Perineum Distance on Sonography

OBJECTIVE

An anorectal malformation (ARM) in neonates requires urgent surgery, with the type of surgery being dependent on the type of malformation (low, intermediate, or high). Distal rectal pouch and perineum (pouch-perineum) distance is reported to be useful for differentiating the type of ARM; however, the impact of an opened fistula on pouch-perineum distance is not well known. The purpose of this study was to evaluate the difference in pouch-perineum distance between neonates with a low-type ARM with and without an opened fistula.

METHODS

We included 24 neonates with low-type ARM who underwent sonography before surgery. Eight neonates already had an opened fistula before sonography, and 16 did not. The pouch-perineum distance was measured using the perineal approach. Mann-Whitney U and Spearman's correlation coefficient tests were used for statistical analysis.

RESULTS

The mean pouch-perineum distance in all neonates with a low-type ARM was 8.3 ± 2.9 mm. The pouch-perineum distance was substantially longer for an ARM with than without an opened fistula (10.6 ± 3.4 mm vs. 7.1 ± 1.7 mm; P = .02). No appreciable correlation was identified between the pouch-perineum distance and the postnatal day of examination (ρ = -.23, P = .26) or birth weight (ρ = .15, P = .47).

CONCLUSION

The pouch-perineum distance is substantially longer in neonates with an ARM with an opened fistula than in those without an opened fistula. Caution should be exercised by the sonographic examiner in evaluating pouch-perineum distance in neonates with an opened fistula to prevent an incorrect surgical procedure based on misdiagnosis of the type of ARM.

Ultrasound imaging of the anorectal malformation during the neonatal period: a comprehensive review

Anorectal malformation (ARM) is classified as low, intermediate, or high; accurate diagnosis of the type during the early neonatal period is important to determine the appropriate initial surgical approach. This review assesses the role of ultrasound examination in the classification of ARM during the neonatal period, with a focus on landmarks on the sonogram, the approach used for sonography, and the optimal examination timing. The following three factors on the sonogram are used for the classification: location of the fistula, the distance between the distal rectal pouch and the anal dimple (perineum) (P-P distance), and the relationship between the puborectalis muscle and the distal rectal pouch. Three approaches can be used to evaluate ARM by ultrasonography, namely, suprapubic, perineal, and infracoccygeal approaches. Each approach has its own advantages and disadvantages. Optimal timing of the ultrasound examination is also important with respect to each factor to classify ARM. We have described the pitfalls of ultrasound in diagnosis of cases, namely ARM with Down syndrome (which tends to be without fistula), ARM with low birth weight, ARM with unusual location of fistula, ARM with opened fistula (where the P-P distance is unreliable), and cloacal malformation (variation of the high-type ARM).