ANTERIOR RABBIT URETHRA AFTER REPAIR OF SURGICALLY CREATED HYPOSPADIAS 681

elasticity/stiffness of the urethra by using a method,impedance planimetry, that has been used to eval-uate the effects of fluid dynamics in other holloworgans such a blood vessels and the intestinal tract(references 1 and 16 in article). While the method-ological and technical aspects of the investigationsare complex, the concept seems attractive insofar asfunctional evaluation of the urethra after surgicalreconstruction is, to date, limited to uroflow studies.Furthermore, fluoroscopic imaging studies are re-ally not helpful in assessing urethral elasticity. Con-cerns have been raised that abnormal flow patternsrecorded after hypospadias repair may be caused by

REFERENCE

1. Idzenga T, Kok DJ, Pel JJ et al: Is the impaired flow after hypospadias correction due

REFERENCE

REPLY BY AUTHORS

rabbits after maternal administration of finasteride

tion.1 This mechanism, in turn, may have an effecton the long-term functional results of the repair.Despite the fact that this study does not demon-strate any increased urethral stiffness in the rabbitmodel of urethral reconstruction, the concept of us-ing impedance planimetry to evaluate postoperativeresults after hypospadias has merit and warrantsfurther study, as it would provide an additional clin-ical tool should it be validated in humans.

Marc Cendron

Department of UrologyHarvard School of Medicine

increased urethral stiffness secondary to scarifica- Boston, Massachusetts

to increased urethral stiffness? J Pediatr Urol 2006; 2: 299.

The authors previously evaluated the biochemicaland biomechanical properties of the pendulous ure-thra in an ex vivo rabbit urethroplasty model (ref-erence 13 in article). Using the same model, theynow describe in vivo biomechanical characteristicsof the urethra 6 months postoperatively by measur-ing the CSA pressure and calculating the circumfer-ential wall tension-strain relation at 3 areas alongthe urethra. The results showed no statistically sig-nificant difference among controls, sham operation,TIP and urethral mobilization groups, except theintermediate and distal CSA in the mobilizationgroup was larger. The authors suggest this findingmight be due to advancement of the proximal ure-thra into the intermediate and distal measuringpoints. Although not statistically significant, theTIP group had a reduced CSA and both surgicalgroups had less distensible urethras. This distinc-

The present experiments measured the biome-chanical changes in the normal rabbit urethra afterthe ventral wall was excised (simulated hypospa-dias) and repaired via TIP or urethral mobilization.I would encourage the authors to investigate theeffects of different hypospadias repairs using a rab-bit model of hypospadias (induced in utero),1 whichmay have more clinical relevance. Unfortunately thecommon test for assessing urethral function, uro-flowmetry, is affected by subject age and bladderfunction. I congratulate the authors for developing abetter methodology for evaluating urethral biome-chanics in the experimental setting.

Eric A. Kurzrock

Department of Pediatric UrologyU. C. Davis Children’s Hospital

Sacramento, California

tion may be relevant clinically.

1. Kurzrock EA, Baskin LS, Jegatheesan P et al: Urethral development in the fetal rabbit and induction of hypospadias: a model for human development. J Urol 2000; 164:1786.

We agree that a rabbit model of hypospadias in-duced in utero would have had more clinical rele-vance (reference 1 in comment by Kurzrock). Wetried to develop a congenital hypospadias model in

but, despite the solid scientific premises, our inves-tigations remained only at a preliminary phase.1,2

Although many studies have been performed onlaboratory animals after maternal administration of

endocrine disruptors, a hypospadias definition re-

ANTERIOR RABBIT URETHRA AFTER REPAIR OF SURGICALLY CREATED HYPOSPADIAS682

sembling that of humans has not been found. Ano-genital distance is an end point for reproductivetoxicological studies, despite disagreement in termi-nology and measurement procedures.3 We do notknow whether the use of anogenital distance mea-surements in addition to the methods we used in the

REFERENCES

Rome, Italy, November 16 –17, 2007.2008.

ever, had the anogenital distance detected in ex-posed males been reduced, the model would havebeen further developed. An animal model with con-genital hypospadias for testing new repair tech-niques is still unavailable. Further studies areneeded to understand the complex mechanics be-

pilot study would have changed the results. How- hind hypospadias development.

1. Lalla M, Danielsen CC, Olsen LH et al: Finasteride-induced hypospadias in male rabbits: myth or re-ality? Presented at Second World Congress onHypospadias and Disorders of Sex Development,

2. Lalla M: An experimental hypospadias studyin rabbits. PhD Thesis, Faculty of Health Sci-ence, University of Aarhus, Aarhus, Denmark,

3. Hsieh MH, Breyer BN, Eisenberg ML et al: Asso-ciations among hypospadias, cryptorchidism, ano-genital distance, and endocrine disruption. Curr

Urol Rep 2008; 9: 137.