<p>A transurethral endoscopic incision is safe for pediatric patients, including neonates and infants; therefore, this procedure has been widely used. Ultrasound guidance during surgery reduces complications; however, reports of transabdominal ultrasonography performed during a transurethral endoscopic incision are lacking. Herein, we report our experience with the simultaneous use of transabdominal ultrasonography in endoscopic procedures such as transurethral and transvaginal endoscopic incision. In case 1, an 11-month-old infant girl was diagnosed with a left renal upper-pole hydronephrosis and left ectopic ureterocele. Ultrasound confirmed the spread of water bubbles from the ureterocele to the bladder through incision site, indicating successful decompression. In case 2, a female neonate was diagnosed at birth with a left duplex ureter, an upper-pole hydronephrosis, and a left ectopic ureterocele. Transabdominal ultrasonography showed that the endoscope was inserted into the distal side of the ureterocele. Subsequently, an endoscopic incision was made at this site. And in case 3, a female neonate with a duplex vagina and uterus was diagnosed with right vaginal atresia and hydrocolpocele. Transabdominal ultrasonography showed that the vaginal septum was endoscopically incised, spreading a water bubble from the left to the right vagina. Although based on a limited small cohort and short follow-up period, simultaneous use of transabdominal ultrasonography in endoscopic procedures is technically safe and effective in visualizing the location of the endoscopic tip and incision site, and can provide real-time feedback on the decompression status of the ureterocele or hydrocolpos, which is important for technical success.</p>