High-pressure distal colostogram in diagnosing anorectal malformations for male patients: our experience to get a high-quality image.

Objective: To summarize our experience with high-pressure distal colostogram (HPC) in diagnosing male anorectal malformations (ARMs) after colostomy.

Method: A retrospective analysis was conducted on 103 male patients with anorectal malformations admitted to our hospital from January 2020 to June 2022. All children were found to have anal atresia after birth, with no obvious fistula in the perineum. A colostomy was performed 1-3 days after birth due to a suspected rectourethral fistula. A high-pressure distal colostogram was conducted on 98 patients who met the criteria and were included in this study. There were 68 cases of transverse colostomy, 13 cases of descending colostomy, and 17 cases of sigmoid colostomy. The average age is 3.60 ± 1.56(1.20-8.67) months. The type of anorectal malformation was confirmed during subsequent anorectoplasty.

Results: 74 (75.5%) patients showed the rectal bladder fistula or rectourethral fistula through a high-pressure distal colostogram, including 14 cases of rectal bladder fistula, 23 cases of rectal prostatic fistula, 37 cases of recto-bulbar fistula. Three children (3.1%) showed tiny fistulas to the perineum and were identified as having rectoperineal fistulas. Twenty-one (21.4%) patients could not show the fistula during the colostogram. These patients were placed with a catheter into the bladder, the contrast was injected into the bladder then the high-pressure distal colostogram was conducted to determine the fistula. Ten children (10.2%) showed a tapered configuration at the distal rectal pouch's anterior aspect before the fistula protruded into the urethra. Based on the position of the fistula and the urethra, 2 cases of rectaurethral prostatic fistula and 8 cases of rectourethral bulbar fistula were determined. Seven cases (7.1%) had a distal rectum extended to the anterior urethra through a fistula and ended subcutaneously at the junction of the penis and scrotum, diagnosed as a rectoperineal fistula. Four patients showed no obvious abnormalities in the external genitalia, while three patients had skin depression at the junction of the penis and scrotum. Four cases (4.1%) presented a symmetrical blind distal rectum extending towards the anus, these were identified as imperforate anus without fistula. The type of anorectal malformation and the location of the rectourethral fistula shown in the colostogram were consistent with the confirmed results during subsequent anorectoplasty.

Conclusion: In conclusion, a properly performed high-pressure distal colostogram combined with voiding cystourethrogram (VCUG) can identify the type of anorectal malformations and the location of the fistula in males.