Comparison of MR and fluoroscopic mucous fistulography in the pre-operative evaluation of infants with anorectal malformation: a pilot study

T2-based magnetic resonance genitography in children with complex anorectal malformations: experience at a tertiary pediatric hospital in Latin America

In children with anorectal malformations (ARMs), it is essential to have a diagnostic imaging method that helps with the evaluation of the internal anatomy. In patients with a persistent cloaca, an ARM variant, in which the measurement of the urethral channel and common channel determines surgical management, there are multiple options for imaging. Magnetic resonance imaging (MRI) is an excellent method for this purpose, from which accurate measurements of channel length can be obtained. Additionally, the use of volumetric/isotropic sequences allows multiplanar reformatting. We present our experience with pelvic MRI and intracavitary non-paramagnetic contrast (MR genitography). This method uses volumetric T2-weighted images and the instillation of saline solution as a contrast agent to distinguish the common channel, length of the urethra, anatomy of the vagina, and presence and location of the rectal fistula. We believe this technique to be particularly useful for those working in settings with limited MRI resources.

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.

Imaging of anorectal malformations: where are we now? Abdominal imaging task force of the European Society of Paediatric Radiology

Anorectal and cloacal malformations are a broad mix of congenital abnormalities related to the distal rectum and anus. Confusion exists between all the forms in this large and heterogeneous group. The spectrum includes everything from anal stenosis, ventral anus, anal atresia (with and without fistula) and the full spectrum of cloacal malformations. Imaging in these conditions is done through the whole armamentarium of radiologic modalities, with very different imaging strategies seen across the centres where these conditions are managed. In 2017, the European Society of Paediatric Radiology (ESPR) abdominal imaging task force issued recommendations on the imaging algorithm and standards for imaging anorectal malformations. This was followed by further letters and clarifications together with an active multispecialty session on the different imaging modalities for anorectal malformations at the 2018 ESPR meeting in Berlin. Through this paper, the abdominal task force updates its guidelines and recommended imaging algorithm for anorectal malformations.

Minimally Invasive Surgery in the Management of Anorectal Malformations

Imperforate anus, a variant of anorectal malformation (ARM), is a common congenital anomaly requiring surgical attention in the newborn period. It may present with a variety of anatomic configurations, largely dependent on the presence and location of a fistula. The location (or characteristics) of a fistula, which usually lies between the gastrointestinal tract and the genitourinary tract or perineum, is often used in determining the type and timing of operative management. This article discusses the work-up and management, modes of treatment and their postoperative outcomes, and continued controversy regarding the use of minimally invasive surgical approaches to ARM.

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.

European Society of Paediatric Radiology abdominal imaging task force recommendations in paediatric uroradiology, part IX: Imaging in anorectal and cloacal malformation, imaging in childhood ovarian torsion, and efforts in standardising paediatric uroradiology terminology

At the occasion of the European Society of Paediatric Radiology (ESPR) annual meeting 2015 in Graz, Austria, the newly termed ESPR abdominal (gastrointestinal and genitourinary) imaging task force set out to complete the suggestions for paediatric urogenital imaging and procedural recommendations. Some of the last missing topics were addressed and proposals on imaging of children with anorectal and cloacal malformations and suspected ovarian torsion were issued after intense discussions and a consensus finding process that considered all evidence. Additionally, the terminology was adapted to fit new developments introducing the term pelvicalyceal dilatation/distension (PCD) instead of the sometimes misunderstood hydronephrosis. The present state of paediatric urogenital radiology was discussed in a dedicated minisymposium, including an attempt to adapt terminology to create a standardised glossary.

High resolution MRI for preoperative work-up of neonates with an anorectal malformation: a direct comparison with distal pressure colostography/fistulography

Objective

To compare MRI and colostography/fistulography in neonates with anorectal malformations (ARM), using surgery as reference standard.

Methods

Thirty-three neonates (22 boys) with ARM were included. All patients underwent both preoperative high-resolution MRI (without sedation or contrast instillation) and colostography/fistulography. The Krickenbeck classification was used to classify anorectal malformations, and the level of the rectal ending in relation to the levator muscle was evaluated.

Results

Subjects included nine patients with a bulbar recto-urethral fistula, six with a prostatic recto-urethral fistula, five with a vestibular fistula, five with a cloacal malformation, four without fistula, one with a H-type fistula, one with anal stenosis, one with a rectoperineal fistula and one with a bladderneck fistula. MRI and colostography/fistulography predicted anatomy in 88 % (29/33) and 61 % (20/33) of cases, respectively (p = 0.012). The distal end of the rectal pouch was correctly predicted in 88 % (29/33) and 67 % (22/33) of cases, respectively (p = 0.065). The length of the common channel in cloacal malformation was predicted with MRI in all (100 %, 5/5) and in 80 % of cases (4/5) with colostography/fistulography. Two bowel perforations occurred during colostography/fistulography.

Conclusions

MRI provides the most accurate evaluation of ARM and should be considered a serious alternative to colostography/fistulography during preoperative work-up.

Key Points

• High-resolution MRI is feasible without the use of sedation or anaesthesia.

• MRI is more accurate than colostography/fistulography in visualising the type of ARM.

• MRI is as reliable as colostography/fistulography in predicting the level of the rectal pouch.

• Colostography/fistulography can be complicated by bowel perforation.

MRI anatomy of anteriorly displaced anus: what obstructs defecation?

BACKGROUND

Anteriorly displaced anus is an anomaly that is debated with regard to its nomenclature, diagnosis and management.

OBJECTIVE

To describe MRI anatomy of the anal canal in children with anteriorly displaced anus and its impact on the process of defecation.

MATERIALS AND METHODS

We prospectively examined ten children (7 girls, 3 boys; age range 7 months to 8 years, mean 3 years) with anteriorly displaced anus between August 2009 and April 2012. Noncontrast MRI examinations were performed on a 1.5-T magnet. T1- and T2-weighted turbo spin-echo images were acquired in axial, sagittal and coronal planes of the pelvis. The anorectal angle and the relative hiatal distance were measured in mid-sagittal images, and compared with those of a control group using the Mann-Whitney test.

RESULTS

In children with anteriorly displaced anus, no anatomical abnormality was depicted at the level of the proximal anal canal. However, the distal anal canal was displaced anteriorly, running out its external muscle cuff, which remained un-displaced at the usual site of the anus. This changes the orientation of the central axis of the anal canal by passing across instead of along the fibers of the longitudinal muscle coat. Children with anteriorly displaced anus had a more obtuse anorectal angle (mean 112.1°), which was significantly greater than that of the control group (mean 86.2°).

CONCLUSION

MRI is a valuable tool in studying the anatomy of the anal canal in children with anteriorly displaced anus. The abnormal orientation of the longitudinal muscle across the anal canal can explain the obstructed defecation in these children. Based on this study, it might be of interest to use MRI in studying equivocal cases and children with unexplained constipation.