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Cortical transit time: understanding utility and pitfalls in children with pelviureteric junction obstruction
Vishesh Jain1, Rakesh Kumar2, Saurabh Arora2
1Department of Pediatric Surgey, All India Institute of Medical Sciences, Ansari Nagar, New Delhi 110029, India.
Insights
Delayed cortical transit time (CTT) in children with pelviureteric junction obstruction (PUJO) significantly improves after surgery. This study shows CTT is a useful management parameter, but renal function must be considered alongside pressure measurements.
Area of Science:
- Pediatric Urology
- Nephrology
- Radiology
Background:
- Pelviureteric junction obstruction (PUJO) is a common congenital anomaly in children.
- Delayed cortical transit time (CTT) has emerged as a potential indicator for surgical intervention in PUJO.
- Understanding post-surgical changes in CTT is crucial for patient management.
Purpose of the Study:
- To evaluate the change in CTT after pyeloplasty in children with PUJO.
- To correlate pre-operative CTT with intra-pelvic kidney pressure.
- To assess the relationship between CTT and renal function.
Main Methods:
- Prospective study including 31 children undergoing pyeloplasty.
- Pre- and post-operative renal ultrasonography and Tc-MAG3 renal scintigraphy for CTT measurement.
- Intra-operative measurement of renal intrapelvic pressure after diuretic administration.
Main Results:
- 71% of patients had prolonged CTT pre-surgery, decreasing to 22.5% post-surgery.
- Mean CTT decreased significantly from 226.1s to 165.4s (p < 0.001) after pyeloplasty.
- No correlation found between CTT and intrapelvic pressure; significant negative correlation between CTT and renal function.
Conclusions:
- Cortical transit time (CTT) assessment is valuable in managing pediatric PUJO.
- Pyeloplasty leads to significant improvement in CTT.
- Renal function should be considered when interpreting CTT values for treatment guidance.
Introduction:
Delayed cortical transit time (CTT) has been recently studied and proposed as a parameter that can predict the need for surgery in children with pelviureteric junction obstruction (PUJO).
Aim:
The aim of this study was to study the change in CTT, after surgery, in children with PUJO and to correlate CTT with intrapelvic pressure of the kidney.
Material And Methods:
A prospective study was performed, and all children who underwent pyeloplasty from January 2016 to December 2017 were included. Pre-operative and postoperative renal ultrasonography and Technetium-99m mercaptoacetyltriglycerine Tc-MAG3 renal scintigraphy were performed. Cortical transit time was measured by a visual method by two different observers. The renal intrapelvic pressure of the kidney was also measured during surgery after giving a diuretic to replicate the diuresis induced during the renal scan. The correlation was studied between the pre-operative CTT and intrapelvic pressures and between the pre-operative CTT and the renal function of the affected kidney.
Results:
Thirty-one children were included in the study. The median age of children who underwent surgery was 50 months (2-168). In 71% of patients, the CTT was prolonged before surgery, whereas only 22.5% had delayed CTT after surgery. The mean CTT before surgery was 226.1 ± 74.8 s and decreased to 165.4 ± 55.9 s after surgery (p= <0.001). The mean intrapelvic pressure was 21 ± 7.5 cm H2O. There was no correlation noted between the intrapelvic pressure and the CTT. A significant negative correlation was noted between the CTT and the different renal function of the kidney.
Discussion:
This is the first prospective study that studies the changes in CTT after surgery. Only retrospective studies had been conducted to date which concluded that CTT was delayed in most of the patients who had been operated. It has been proposed that the prolonged CTT is due to raised pressure in the kidney secondary to obstruction. This study did not find any correlation between the pressure and CTT. The significant negative correlation between CTT and renal function also emphasizes the need to take the renal function into consideration before interpreting and using the absolute value of CTT for guiding treatment.
Conclusion:
Cortical transit time assessment by the visual method is a useful parameter in the management of children with PUJO. There is a significant improvement in CTT after surgery.
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