Korean J Radiol.  2009 Aug;10(4):355-360. 10.3348/kjr.2009.10.4.355.

Imperforate Anus: Determination of Type Using Transperineal Ultrasonography

• Choi YH
• Kim IO
• Cheon JE
• Kim WS
• Yeon KM

• KMID: 1777263
• DOI: http://doi.org/10.3348/kjr.2009.10.4.355

Abstract

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.

Keyword

Anus; Imperforate anus; Ultrasound (US); Ultrasonography; Infant

MeSH Terms

Anus, Imperforate/classification/surgery/*ultrasonography
Female
Fistula/ultrasonography
Humans
Infant, Newborn
Male
Rectal Fistula/ultrasonography
Ultrasonography/methods
Urinary Bladder Diseases/ultrasonography

Figure

• 

  Fig. 1 Transperineal sonography of normal female anatomy is shown. Transperineal sonogram from normal one-week-old girl showing bladder (B), symphysis pubis (S) and vagina (V) between urethra (U) and rectum (R) and normal rectum directing posteriorly to anus is shown. Echogenic fat plane was present between rectum and vagina (arrow).

• 

  Fig. 2 Schematic diagram of various internal fistulas for male and female imperforate anus is presented.

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  Fig. 3 Findings for high-type imperforate anus with recto-urethral fistula are shown. A. Transperineal sonogram shows low echogenic fistula (arrows) between rectum and urethra. B. Distal colostogram shows rectoposterior urethral fistula (arrow), which was correlated with US findings.

• 

  Fig. 4 Findings for intermediate-type imperforate anus with recto-bulbar urethral fistula are shown. A. Transperineal US shows long low echoic fistula tract (arrow) between rectum and bulbous urethra. B. Retrograde urethrogram shows fistula (arrow) between rectum and bulbous urethra.

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  Fig. 5 Findings for low-type imperforate anus with anocutaneous fistula are shown. Distal rectum (arrows) abnormally courses towards perineum, anterior to normal location of anus.

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  Fig. 6 Pouch to perineum distance according to imperforate anus type is plotted. Some overlap of pouch to perineum distances was observed among imperforate anus types. However, all cases with pouch to perineum distance > 16 mm were high-type imperforate anus and all cases with pouch to perineum distance < 5 mm were low-type imperforate anus.

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