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An Appraisal of Invertograms and Distal Colostograms in


Suthas Horsirimanont MD* ,
Surasak Sangkhathat MD*, Panpen Utamakul MD**,
Jirawan Chetphaopan MD**, Sakda Patrapinyokul MD*
* Department of Surgery, Faculty of Medicine, Prince of Songkla University
** Department of Radiology, Faculty of Medicine, Prince of Songkla University


Objectives : To determine the accuracy of two main radiologic tools currently employed in the clinical
management of anorectal malformations, the invertogram and the distal colostogram. The data will be useful
as a basis for quality assurance as well as for future comparisons in case there are innovations to be
Material and Method : Radiological materials and clinical records of infants with anorectal malformations
operated on in Songklanagarind Hospital from 1995 to 2001 were retrieved. Each record was blindly
reviewed by two radiologists and one pediatric surgeon. Using operative findings as the gold standard, the
accuracy of an invertogram in diagnosing low anomalies and the accuracy of a distal colostogram in
screening cases that needed a laparotomy and in detecting internal fistulas were determined. The quality of
the films was also categorized and poor quality studies were excluded from the analysis. Cases of common
cloaca were not included in the level reading analysis.
Results : Radiologic materials from 59 patients were examined, including 26 invertograms and 49 distal
colostograms. Among 52 cases whose neonatal history could be traced, 29 (55.8%) cases exhibited clinical
evidence of anomalies level. Two invertograms and 5 colostograms were graded as poor quality and excluded
from the analysis. The overall sensitivity of invertograms in detecting low anomalies was 33.3%, whereas,
specificity was 66.7%. Analyzing only infants with a blind rectal pouch, the sensitivity and specificity to
detect low anomalies were 33.3% and 75.0%, respectively.
The sensitivity of distal colostograms in detecting a fistula was 60.0% in males and 62.5% in
females. Distal colostograms diagnosed ‘high-type anomalies’ in 7 cases and correctly detected 2 cases of
vesical fistula which needed APSARP. No prostetic-urethral fistulas showed a radiological high level.
Conclusion : The study found poor diagnostic sensitivity of invertograms in detecting low type anomalies
which deserved primary anoplasty. However, the data support the role of a distal colostogram in diagnosing
high anomalies, despite its low sensitivity in detecting urethral fistulas.

Keyword : Anorectal malformations, Invertogram, Colostogram

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