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

Abstract

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 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

“…For neonates with an opened fistula and a pouch-perineal distance greater than 10 mm, an augmented pressured colostogram can be useful for correct diagnosis. 3 Although previous studies have demonstrated the utility of sonography for classifying the type of ARM, [8][9][10][11][12]17,19,20 to our knowledge, ours is the first study to have evaluated the possible effect of an opened fistula on the measured pouch-perineum distance. The longer pouch-perineum distance in neonates with the low-type ARM with an opened fistula might be due to the early passage of meconium passed through the fistula, which decompresses the distal rectal pouch, prolonging the pouch-perineum distance (Figure 3).…”

“…The type of ARM is classified on the basis of sonographic findings of the pouch-perineal distance, location of the fistula, and the relationship between the puborectalis muscle and the distal rectal pouch. 7,9,10,12,19 To our knowledge, there have been no reports on which of these factors is more appropriate to classify the type of ARM in neonates; therefore, in the presence of an opened fistula, the type of ARM is generally classified as a low-type anocutaneous or anovestibular fistula. For neonates with an opened fistula and a pouch-perineal distance greater than 10 mm, an augmented pressured colostogram can be useful for correct diagnosis.…”

“…10,17,19,20 Furthermore, sonography can be also used to assess other accompanying anomalies and assist with the surgical procedure. 12 Therefore, sonography is recommended as an evaluative and diagnostic tool for neonates with an ARM.…”

“…2,6,7 Previous reports showed that a cutoff distance of approximately 10 mm was used to differentiate between low and intermediate/high ARM types. [7][8][9][10][11][12][13][14] Although changes in the distal rectal pouch have been reported based on the postnatal date of the examination, 11 the difference in pouch-perineum distance between neonates with an ARM with an opened fistula and those without an opened fistula has not been reported. In some cases, meconium is excreted via the fistula, which is assumed to change the pouch-perineum distance.…”

Complications after Surgical Correction of Anorectal Malformations

“…29,31,32,34 High-type ARM is characterised by poor muscle quality, which may render anal prolapse an inevitable complication, with a higher likelihood of recurrence than in low-type ARM. 26,35 It may be accidentally detected on an MRI requested to evaluate the levator ani muscle. 31,36…”