Computed tomograpy evaluation of ureteral length in children

JJ stent dislodgement in the distal ureter: how to recover it in preschool children?

Double-J ureteral stents are usually placed after various urological procedures. The dislodgement of their distal ringlet is a rare complication, whose retrieval is arduous in younger children, due to the small ureteral caliber. We propose our innovative endoscopic approach to recover the dislodged JJ stent. Under 8-9.8 Ch cystoscopy, the ureteral meatus is gently cannulated with a 00.18″ guidewire, then a balloon catheter Passeo 18 3-4 mm (Biotronik, Lake Oswego, OR, USA) is coaxially inserted. A pneumatic dilatation of the vesical-ureteral junction is performed up to 8 atmospheres for 5 minutes under direct vision. Consequently, the ureteral meatus allows the cystoscope passage, and the JJ-stent can be recovered thanks to endoscopic grasping forceps. A mono-J stent is then left in place for 24 hours. Four patients aged 8 months - 4 years have been successfully treated with this approach after that JJ migration was found intraoperatively or during ultrasonography. No intra- or postoperative complications occurred. Postoperative hospital stay was prolonged for one day. During 29.5 medium follow-up no clinical or ultrasonographic signs of vesical-ureteral reflux ensued. Our cystoscopic approach is effective and safe to ensure a prompt endoscopic JJ retrieval without changing neither surgical approach nor the anesthesiological support. We believe that all the pediatric urology centers should know the procedure and have small size balloon catheter available.

Can we predict urethral length of boys? - An observational study

INTRODUCTION

An additional knowledge about normal anatomy of urethra in boys can improve clinical outcome of any urological interventions. This will also reduce catheter related complications like intra vesical knotting and urethral injuries. At present there is no systematic data available which has studied the urethral length of boys. We have done this study to analyse the length of urethra in boys.

AIM

The aim of the study is to measure the urethral length in Indian children from the age of 1 year till 15 years and plot a nomogram. Furthermore to analyse the influence of anthropometry on urethral length and derived a formula to predict the urethral length in boys.

STUDY DESIGN

This is a single institution prospective observational study. After obtaining clearance from the institutional review board, a total of 180 children from the age of 1-15 were recruited for the study. The urethral length was measured during Foley's catheter removal. Other data like age, weight, and height of the patient are collected and the obtained values were analysed with SPSS software. The acquired figures were further used to derive formulae to predict urethral length.

RESULTS

A nomogram of urethral length based on age was plotted. With collected figures, five separate formulae were derived to calculate the urethral length based on the age, height and weight. Furthermore for day-to-day use we have deduced a formulas to calculate urethral length which are simplified forms of original formulae.

DISCUSSION

The length of urethra of a new-born male is 5 cm, which attains 8 cm by three years of age and to 17 cm by adulthood. There were attempts to measure the urethral length in adults using cystoscopy, Foley's catheter and different imaging techniques like Magnetic Resonance Imaging and dynamic retrograde urethrography. Simplified formulae which has been derived from this study for clinical use is Urethral length = 8.7 + Age (in year) × 0.55 CONCLUSION: Our results will complement the current anatomical understanding of the urethra. This evades some rare complications of catheterisation and facilitate reconstructive procedures.

Management of proximal migration of double-J stents after Anderson-Hynes pyeloplasty in children

INTRODUCTION

Proximal migration of double J stents after pediatric pyeloplasty is rare. Although retrograde removal of migrated stents is more common, the small calibre of the pediatric ureter may necessitate antegrade retrieval. Many techniques are described for the same in adults however, pediatric literature is sparse. We aim to describe the management of proximally displaced stents after pediatric pyeloplasty.

MATERIALS AND METHODS

This retrospective study included all children (<17 years age) who underwent retrieval of proximally displaced DJ stents after pyeloplasty between 2007 and 2019 at a single institution. The retrograde technique employed ureteroscopic retrieval with a grasper while in the antegrade technique, an access sheath was placed percutaneously into a calyx and Nephroscopic retrieval was performed.

RESULTS

There were 8 children (6 boys and 2 girls) of which 4 were infants. Median age was 3.5 (0.5-12) years and median follow-up was 7.5 (4-47) months. Two children had been referred with displaced stents after pyeloplasty from other centres. The incidence of proximal stent migration was 6/1644 (0.4%). Open pyeloplasty had been performed in seven while one child had undergone laparoscopic pyeloplasty. The lower coil of the migrated stent was in the renal pelvis in 6 (complete) and ureter in 2 (partial migration). Those with partial migration underwent successful ureteroscopic retrieval. Three infants required Antegrade stent removal while ureteroscopic retrieval was successful in an older child with complete stent migration. Nephrectomy for loss of function and redo pyeloplasty for pelvi-ureteric stricture was performed in one each. One child had self-limiting fever (Clavien 1) after stent removal. All had normal drainage on renogram after 6 months. The cause of proximal stent migration was likely to be an inadequate lower coil (<180°) in 5 children and a capacious pelvis with narrow ureter in one infant. The cause could not be ascertained in two children who were referred from other centres. The management algorithm for retrieval of proximally migrated DJ stents, is depicted in Fig. 3.

CONCLUSIONS

Proximal migration of DJ stent after pyeloplasty is a rare complication which may be safely managed with a stepwise approach using both Antegrade and retrograde techniques. Accurate stent length, adequate distal coil and appropriate placement are essential to avoid stent migration.

Comparing Aachen Minipigs and Pietrain Piglets as Models of Experimental Pediatric Urology to Human Reference Data

INTRODUCTION

Swine had special roles in the development of minimally invasive procedures to treat vesicoureteral reflux, and minipigs have been gaining ground in recent years in experimental pediatric urology as they combine small size with less vulnerable adult physiology, but their suitability as a model has never been assessed. We therefore compared a landrace piglet with a juvenile minipig to elucidate comparability.

METHODS

We evaluated five 3-week old Pietrain piglets and five 3-month old Aachen Minipigs as representatives of landrace and minipig models based on their expected bodyweight being similar to a newborn human. We compared renal weight, volume - via the ellipsoid formula - and ureteral length. In addition, we calculated porcine renal function via Gasthuys' formula. In order to compare the groups with previously published values for infants, we used resampling techniques to allow comparison to humans.

RESULTS

Renal weight was higher in humans than in Pietrain piglets (ΔL = 7.6 g; ΔR = 5.4 g) and Aachen Minipigs (ΔL = 11 g; ΔR = 9.4 g). Renal volumes in humans were higher than in both Pietrain piglets (ΔL = 5.6 mL, p < 0.001; ΔR = 3.7 mL, p = 0.004) and Aachen Minipigs (ΔL = 8.1 mL; ΔR = 6.6 mL; both p < 0.001). Ureteral lengths in humans and both pig breeds were comparable as were estimated renal functions between both pig breeds.

DISCUSSION AND CONCLUSION

Both landrace piglets and juvenile minipigs are suitable models for experimental pediatric urology as parameters did not differ between them. In addition, the anatomic parameters are comparable or smaller than in infants. This might facilitate translational research as technical failure is less likely in larger organs. Additional research is necessary to cover higher age ranges than those included in the present pilot study.