The radiologic evaluation of imperforate anus. An approach correlated with current surgical concepts

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).

Distance Between the Distal Rectal Pouch and Perineum in Neonates of Low-Birth Weight With Imperforate Anus

This study was to evaluate the correlation between birth weight and the distance between distal rectal pouch and perineum (P-P distance) and to determine a cutoff value for P-P distance to diagnose low-type imperforate anus in neonates with low-birth weight (LBW).We included 15 neonates with LBW (mean weight, 2012 ± 470 g; range, 906-2452 g) and imperforate anus (surgically confirmed: 11 low type and 3/1 intermediate/high type), who underwent ultrasonography on the day after birth. Type of imperforate anus was defined based on the International Classification of Anorectal Anomalies. The P-P distances on ultrasonograms were measured. Pearson correlation coefficient test and receiver operating characteristic curve were used for statistical analyses.Among all 15 neonates, nonsignificant correlation was observed between the birth weight and P-P distance (r = 0.36; P = 0.18). Mean P-P distance was 9.0 ± 6.6 mm (range, 1.0-24.0 mm) in all neonates, 5.7 ± 2.8 mm (range, 1.0-11.0 mm) in the 11 neonates with low-type imperforate anus, and 18.3 ± 9.1 mm (range, 14.0-24.0 mm) in the 4 neonates with intermediate-/high-type imperforate anus. Using cutoff P-P distance of 12.5 mm, sensitivity and specificity for diagnosis of low-type imperforate anus were 100% (11/11) and 100% (4/4), respectively.In conclusion, nonsignificant correlation was observed between P-P distance and birth weight, and cutoff P-P distance to diagnose low-type imperforate anus was 12.5 mm. Despite the very small sample size in our study, and only 4 neonates with intermediate-/high-type imperforate anus, these findings are important because surgical management whether transperineal anoplasty or diverting colostomy is decided based on the type of imperforate anus, and P-P distance to diagnose the type of imperforate anus was feasible even in neonates with LBW.

Diagnostic Accuracy of Sonography for Detection of a Fistula on the Birth Day in Neonates With an Imperforate Anus: Comparison of Diagnostic Performance Between Suprapubic and Perineal Approaches

OBJECTIVES

To evaluate the diagnostic accuracy of sonography for detection of an internal fistula on the birth day in neonates with an imperforate anus and to compare the diagnostic performance between the suprapubic and perineal approaches.

METHODS

We included 46 neonates with an imperforate anus (29 low type and 17 intermediate/high type) who underwent sonography by both the suprapubic and perineal approaches on the birth day. Thirty-nine neonates had internal fistulas, and 12 did not, as surgically proven. Two blinded radiologists evaluated the suprapubic and perineal sonograms for the presence of the internal fistula in consensus. A final diagnosis of the internal fistula was determined on the basis of the findings of both approaches. A receiver operating characteristic analysis was used to compare the diagnostic performance for detection of an internal fistula between the suprapubic and perineal approaches.

RESULTS

The sensitivity, specificity, and accuracy of the final diagnosis based on the findings of suprapubic, perineal, and both approaches were 52.9%, 79.4%, and 79.4%; 75.5%, 75.5%, and 75.5%; and 58.7%, 78.3%, and 78.3%, respectively. The diagnostic performance of the perineal approach was significantly better than that of the suprapubic approach (P < .0001).

CONCLUSIONS

The diagnostic accuracy of sonography for detection of an internal fistula on the birth day exceeded 75% in neonates with an imperforate anus, and sonography on the birth day is feasible. The perineal approach had superior diagnostic performance over the suprapubic approach. Thus, when evaluating an internal fistula by sonography, we recommend using the perineal approach in addition to the suprapubic approach.

Sonography for an Imperforate Anus: Approach, Timing of the Examination, and Evaluation of the Type of Imperforate Anus and Associated Anomalies

This systematic review outlines the role of sonography in an imperforate anus. The diagnostic performance for type of imperforate anus is superior on the day after birth than that on the day of birth by using the pouch-perineum distance. Three approaches can be used (suprapubic, infracoccygeal, and perineal). The pouch-perineum distance, fistula location, and relationship between the puborectalis muscle and distal rectal pouch are useful for classifying the type of imperforate anus. However, the pouch-perineum distance measured has an overlap between the low and high/intermediate types of imperforate anus. Sonography can be useful for some of the associated anomalies and helpful for surgeons in some cases.

Comparison of Diagnostic Accuracy for the Low-Type Imperforate Anus Between Prone Cross-Table Radiography and Sonography

OBJECTIVES

To compare the diagnostic accuracy for the low-type imperforate anus between prone cross-table radiography and sonography.

METHODS

We included 20 neonates with imperforate anus: 13 with a surgically proven low type and 7 with an intermediate or high type. The distance between the distal rectal pouch and the perineum (pouch-perineum distance) was measured by both sonography and prone cross-table radiography. A previously established pouch-perineum distance of 10 mm was used as the cutoff for diagnosis of a low-type imperforate anus. The fistula location was also determined with sonography. We then compared the diagnostic accuracy of the imaging methods for a low-type imperforate anus using the cutoff value of the pouch-perineum distance alone and both the cutoff value of the pouch-perineum distance and fistula location. The McNemar test was used for statistical analysis.

RESULTS

With the use of only the pouch-perineum distance, the diagnostic accuracy for the low-type imperforate anus based on sonographic measurements was comparable with the accuracy achieved by prone cross-table radiographic measurements (60.0% [12 of 20] versus 45.0% [9 of 20]; P = .625). With the use of the pouch-perineum distance and fistula location, the diagnostic accuracy of sonography was significantly better than the accuracy of prone cross-table radiography (90.0% [18 of 20] versus 45% [9 of 20]; P = .012).

CONCLUSIONS

The diagnostic accuracy of sonography for the low-type imperforate anus based on both the pouch-perineum distance and fistula location is better than that of prone cross-table radiography. If the pouch-perineum distance on prone cross-table radiography is greater than 10 mm, a sonographic examination to determine the fistula location could be recommended.

Changes in the Distance Between the Distal Rectal Pouch and Perineum From the Birth Day to the Next Day in Neonates With an Imperforate Anus

OBJECTIVES

To evaluate changes in the distance between the distal rectal pouch and the perineum (pouch-perineum distance) from the birth day to the next day and to determine which day is better for diagnosis of a low-type imperforate anus in neonates.

METHODS

We reviewed medical records at our hospital from May 2003 to August 2015 and identified 9 neonates with a radiographically and surgically proven low-type imperforate anus and 9 with high/intermediate types of imperforate anus who had undergone sonography on both the birth day and the next day before the first surgical treatment. The sonograms were reviewed to measure the pouch-perineum distance at both examinations. The Wilcoxon signed rank sum test and a receiver operating characteristic curve analysis were used for the statistical analyses.

RESULTS

The pouch-perineum distance on the next day (mean ± SD, 9.37 ± 4.89 mm; range, 2.1-20.9 mm) was significantly shorter than on the birth day (15.75 ± 6.67 mm; range, 8.1-37.2 mm; P = .001). The receiver operating characteristic analysis showed significantly better diagnostic performance (P < .001) of the pouch-perineum distance on the next day (area under the curve, 0.864) versus the birth day (0.420) for the low-type imperforate anus.

CONCLUSIONS

The pouch-perineum distance was shorter on the next day than on the birth day, and the diagnostic performance of the pouch-perineum distance on the next day was significantly superior to that on the birth day for the diagnosis of a low-type imperforate anus. We recommend sonography on the next day in neonates with an imperforate anus when possible.

Bowel perforation in newborn with anorectal malformation and no fistula at presentation

PURPOSE

Anorectal malformation (ARM) in newborns with no fistula at presentation resembles intestinal obstruction. The aim of this study is to study the factors associated with bowel perforation in this group of patients.

METHODS

From 2000 to 2012, 106 newborns with ARM were managed in our hospital. Thirty neonates without fistula at presentation were included in this study. Demographic data and the incidence of bowel perforation were studied.

RESULTS

Twenty-nine male and 1 female were included in the study. Five patients were born premature and six patients had low birth weight. Six patients had Down's syndrome and 12 patients had associated anomalies. Cross-table lateral x-ray in prone position was performed from 20 to 24 hours after birth. All operations were performed within 48 hours after birth. One neonate underwent primary anoplasty. Twenty-nine neonates underwent colostomy. Two males developed bowel perforation before surgery (at 33 and 36 hours after birth). Perforation was associated with low birth weight (p=0.034) and was not associated with prematurity (p=0.31), Down's syndrome (p=0.634) or the presence of other associated anomalies (p=0.687).

CONCLUSIONS

In newborns with ARM, bowel perforation can occur within 36 hours after birth. Forty-eight hours of waiting is too long as it risks perforation. In this study, a neonate with low birth weight was trended toward bowel perforation.

Management and outcome of low anorectal malformations

Low anorectal malformation comprises about half of all anorectal anomalies. Most of the literature concerning management of anorectal anomalies is centred around the treatment and outcome of high anomalies. The management of low anomalies has been considered significantly less challenging than high anomalies. Also, the outcome of low anomalies has traditionally been considered good. However, recent more critical long-term follow-up reports show a different picture. Many patients with low anomalies suffer from long-term anorectal functional problems, especially constipation but also soiling that occurs in a significant percentage of patients. In this review, we compile the recent views on the diagnosis, surgical treatment and outcome of low anorectal anomalies. We also present an algorithm for the management of these anomalies. The emphasis on the surgical management of low anorectal anomalies is to use as minimally invasive operative methods as possible and preserve the native mechanisms of continence that usually are much better preserved than in more severe high anomalies.

Imperforate anus: determination of type using transperineal ultrasonography

Objective

This study was designed to assess the usefulness of transperineal ultrasonography (US) for the determination of imperforate anus (IA) type.

Materials and Methods

From January 2000 to December 2004, 46 of 193 patients with an IA underwent transperineal US prior to corrective surgery. Sonographic findings were reviewed to identify the presence of internal fistulas and to determine "distal rectal pouch to perineum (P-P)" distances. IA types were determined based on the sonographic findings, and the diagnostic accuracy of transperineal US was evaluated based on surgical findings.

Results

Of the 46 patients, 17 patients were surgically confirmed as having a high-type IA, three patients were confirmed as having an intermediate-type IA and 26 patients were confirmed as having a low-type IA. The IA type was correctly diagnosed by the use of transperineal US in 39 of the 46 patients (85%). In 14 of the 17 patients with a high-type IA, internal fistulas were correctly identified. All cases with a P-P distance > 16 mm were high-type IAs and all cases with a P-P distance < 5 mm were low-type IAs.

Conclusion

Transperineal US is a good diagnostic modality for the identification of internal fistulas in cases of high-type IA and for defining the IA level.

Imaging the Pediatric Prostate

The prostate gland is not often the target of imaging in children but may be imaged during investigation of symptoms related to the lower genitourinary tract such as hematuria, urinary retention, dysuria, and incontinence or during an evaluation for suspected congenital anomalies. Ultrasound and voiding cystourethrography are useful for initial evaluation of congenital and neoplastic disorders of the prostate. MR imaging and CT are useful in delineating more detailed anatomy before surgical planning and in determining the organ of origin in a patient who has a large pelvic mass.

Transanal endoscopic-assisted proctoplasty--a novel surgical approach for individual management of patients with imperforate anus without fistula

BACKGROUND/AIM

Imperforate anus without fistula consists of a spectrum of defects with variable distance between the rectal pouch and the perineum. We have developed a novel surgical approach for individual management of these patients based on precise knowledge of the level of the anomaly.

METHODS

All consecutive patients with imperforate anus without fistula between 2002 and 2004 had sigmoidostomy performed after having failed to pass meconium in the first 24 hours. The upper pouch was intraluminally visualized using retrograde endoscopy through the sigmoid mucous fistula. The distal termination of the rectum was clearly identified as by convergence of the anal columns. Bright translumination of the endoscope light from the rectum to the anal dimple within the external sphincter indicated a low malformation amenable to transanal proctoplasty. The rectum was incised from below under endoscopic visual control. Poor translumination indicated a higher defect, in which case, the operation was converted to standard posterior sagittal anorectoplasty.

RESULTS

Seven patients (6 boys) were identified. Four patients (3 boys) completed transanal endoscopic-assisted proctoplasty. In all cases, the convergence of anal columns indicating rectal termination was right above the anal pit at the site of the maximal external sphincter squeeze. In 3 patients, the operation was converted to posterior sagittal anorectoplasty after verification of a higher anomaly by endoscopy. There were no operative complications. The median follow-up was 3 months (range, 1-26 months). All patients have an appropriate size anus and regular bowel actions.

CONCLUSIONS

Transanal endoscopic-assisted proctoplasty allows safe and anatomical reconstruction of the anorectum, as well as contemporaneous closure of the sigmoidostomy in a significant proportion of patients with imperforate anus without fistula, avoiding the potential complications associated with the open posterior sagittal approach.

Imperforate anus: US determination of the type with infracoccygeal approach

PURPOSE

To assess the usefulness of infracoccygeal transperineal ultrasonography (US) in differentiation between high- and low-type imperforate anus.

MATERIALS AND METHODS

Infracoccygeal US was prospectively performed with a 7-10-MHz linear-array transducer prior to corrective surgery in 14 neonates with imperforate anus. The approach site was just inferior to the coccyx and posterior to the anus. Transverse images of the anorectal area were obtained. The puborectalis muscle was identified, and the relationship between the puborectalis muscle and the distal rectal pouch was evaluated. US findings were compared with surgical findings.

RESULTS

In 10 neonates, a low-type imperforate anus was correctly diagnosed at infracoccygeal US. In those with low-type imperforate anus, the puborectalis muscle was seen as a hypoechoic U-shaped band (n = 10), and the distal rectal pouch passed through the puborectalis muscle (n = 10). In four neonates with high-type imperforate anus, the puborectalis muscle was not identified (n = 4).

CONCLUSION

Infracoccygeal transperineal US enables the determination of the type of imperforate anus.

Congenital anomalies of the small intestine, colon, and rectum

Congenital anomalies of the gastrointestinal tract are a significant cause of morbidity in children and, less frequently, in adults. These abnormalities include developmental obstructive defects of the small intestine, anomalies of the colon, anomalies of rotation and fixation, anorectal anomalies, and intestinal duplications. Neonates with complete high intestinal obstruction do not usually require further radiologic evaluation following radiography, whereas those with complete low obstruction should undergo a contrast material enema examination. An upper gastrointestinal series must be performed in all patients with incomplete intestinal obstruction because management is different in each case. In low intestinal obstruction, ultrasonography (US) may help differentiate between small bowel obstruction and colonic obstruction. In addition, US can help correctly identify meconium ileus and meconium peritonitis and is useful in the diagnosis of enteric duplication cysts. In malrotation and anorectal anomalies, computed tomography (CT) and magnetic resonance (MR) imaging can provide superb anatomic detail and added diagnostic specificity. Intestinal duplications manifest as an abdominal mass at radiography, contrast enema examination, or US. At CT, most duplications manifest as smoothly rounded, fluid-filled cysts or tubular structures with thin, slightly enhancing walls. At MR imaging, the intracystic fluid has heterogeneous signal intensity on T1-weighted images and homogeneous high signal intensity on T2-weighted images. Familiarity with these gastrointestinal abnormalities is essential for correct diagnosis and appropriate management.

The role of radiology in children with anorectal anomalies; with particular emphasis on MRI

Anorectal anomalies have a reported incidence of between 1 per 1000 and 1 per 9630 live births. The international classification subdivides anorectal malformations into high, intermediate, low and miscellaneous deformities with emphasis on the sex of the child. The classification is based on where the rectum terminates in relation to the levator ani muscles above the levator is termed a high (supralevator) lesion, at the level of the levator intermediate, and below is a low or translevator anomaly. A modified classification has recently been proposed by Pena based on his anatomic observations during posterior sagittal anorectoplasty-the terms high, intermediate and low lesions continue to be used but with slightly different connotations. Approximately 50% of all patients with anorectal anomalies have associated other congenital lesions. These lesions necessitate a variety of radiological investigations which will be outlined briefly. The pertinent muscular anatomy of the pelvic floor and recent advances in surgical techniques will be discussed. The particular role of MRI in the evaluation of the pre-operative newborn or infant prior to definitive pull-through repair surgery and the post-operative, older, paediatric patient with continuing problems will be reviewed. Reference to the other radiological options, and their usefulness, in the evaluation of anorectal malformations will be made throughout the text.

Anal agenesis with recto-bulbar fistula

Four cases of anal agenesis with rectobulbar fistula, a rare type of anorectal anomaly, are described along with the preferred mode of radiological investigation to demonstrate the fistula.

Rectourethral fistula on the urethrogram

Radiologic demonstration of a rectourethral fistula is of importance in the evaluation of the male neonate with imperforate anus. After pull-through operation a remnant of the fistula may remain as a small unimportant sinus tract or may cause problems.

An analysis of ultrasound scanning as a guide in determination of "high" or "low" imperforate anus

The classic upside-down abdominal roentgenogram and the use of pelvic reference points have frequently been inaccurate in assessing the level of the distal pouch in patients with imperforate anus. The ultrasonic study described is different from that previously reported and allows more precise localization of the distal rectal pouch. A review of our experience allows us to make certain definitive statements about this diagnostic modality.

Urologic implications of imperforate anus

Recent clinical studies have documented the high association of genitourinary and lumbosacral spine anomalies with imperforate anus. Many of these associated anomalies may go undetected unless special diagnostic studies are performed, and these genitourinary anomalies can be the cause of significant clinical morbidity in later life if not managed properly initially. All neonates with imperforate anus should therefore undergo radiographic examination with lower spine films, intravenous pyelography and voiding cystourethrography, and cystoscopy should be reserved for those with cloaca deformity or those whose x-ray films demonstrate urinary anomalies requiring further workup. Significant morbidity involving the genitourinary tract may be encountered after surgical treatment of the anorectal anomaly, particularly if total anorectal reconstructions are performed in the neonatal period.