Is urodynamic evaluation a must in all operated cases of open neural tube defects

Spina bifida is a common cause of pediatric neurogenic bladder. It causes renal failure in almost 100% of patients if the associated detrusor sphincter dyssynergia (DSD) is inadequately managed. Detrusor instability and high detrusor pressures (Figure) have been implicated as the major factors predictive of renal damage in these patients. Urodynamic studies provide early identification of "at risk" kidneys so that appropriate intervention can be made. However, the role in post-operative patients of spina bifida who have no clinical manifestations remains unclear.

To study the bladder dynamics in asymptomatic post-operative patients of spina bifida and to determine whether routine urodynamic study is justifiable.

Urodynamics was performed on 15 operated patients of spina bifida who did not have any neurological deficit and were asymptomatic.

The mean age of the patients was 4.97 years. None of the patients had any urological complaints with their ultrasonography being normal. None had scars on nuclear scan. Of the 15 patients, 12 (80%) had abnormal findings on urodynamic assessment. Three patients (20%) had detrusor pressures greater than 40 cm of H₂O. One patient had significant residual urine and detrusor instability.

The use of urodynamic studies in asymptomatic patients of spina bifida remains controversial, with one school of thought advocating early invasive urodynamic testing. In contrast, some favor noninvasive sonological monitoring, reserving invasive tests only for patients with renal tract dilatation. In our subset of patients none had renal tract dilatation but three patients (20%) had "at risk" bladders. These patients would benefit from early intervention aimed at renal preservation. The study is limited by a small sample size because of the relative rarity of the patient profile included. A further multicenter study with a case-control design could conclusively indicate the role of urodynamic testing in these patients.

Patients of spina bifida, even when asymptomatic, have a high incidence of unsafe bladders. Early identification and appropriate measures can protect kidneys from long-term damage, hence urodynamic profiling is mandatory for identification of potentially high-risk bladders.