Posterior urethral valves in the newborn: treatment and functional results

Collagen Directly Stimulates Bladder Smooth Muscle Cell Growth In Vitro: Regulation by Extracellular Regulated Mitogen Activated Protein Kinase

PURPOSE

Bladders clinically subjected to excessive pressure or distention demonstrate an altered extracellular matrix (ECM) composition. We determined how an altered collagen substratum might affect bladder smooth muscle cell (bSMC) growth in vitro and probed the mechanism of this response.

MATERIALS AND METHODS

Primary culture rat bSMCs were seeded onto culture plates pre-coated with normal type I collagen (NC) or heat denatured type I collagen (DNC) under standard culture conditions. In separate experiments bSMCs from the 2 substrates were enzymatically released and changed to growth on normal collagen (NC-->NC or DNC-->NC) or denatured collagen (DNC-->DNC or NC-->DNC). At 24 hours proliferation was assessed by 3H-thymidine incorporation. Statistical significance in triplicate wells was determined by ANOVA.

RESULTS

The proliferation of bSMCs on DNC was 5-fold greater than on NC (p <0.0001). Passage onto damaged collagen (DNC-->DNC) showed 2-fold further augmentation in proliferation (p <0.0001) but only a 50% decrease when NC was reintroduced (DNC-->NC) (p <0.001). Conversely replating on NC (NC-->NC) generated a 33% decrease in the already low proliferation rate (p <0.001) but 9-fold stimulation of proliferation when changed to damaged ECM (NC-->DNC) (p <0.0001). The mitogenic effect of damaged ECM on bSMC growth was abolished by specific inhibition of extracellular regulated kinase mitogen activated protein kinase signaling using PD98059.

CONCLUSIONS

Damaged type I collagen (ECM) is mitogenic to bSMCs. The response is amplified by re-exposure to DNC. However, mitogenicity is only partially reversible by re-introducing NC. These results demonstrate striking bSMC responsiveness to ECM conformation. Signaling through the extracellular regulated kinase mitogen activated protein kinase pathway supports bSMC-ECM interaction. We speculate that remodeling the ECM in vivo may regulate bSMC growth.

Postnatal management of hydronephrosis diagnosed in utero

In this review we identify the causes of antenatal hydronephrosis and detail management options. A large majority of these patients can be treated safely and effectively after birth.

Evolution of upper urinary tract and renal function in patients with posterior urethral valves

From January 1972 to June 1993, 166 patients with posterior urethral valves (PUV) were treated in our surgical department, 59 with a milder form of PUV (upper urinary tract [UUT] complication rate 29%) and 107 with a severer form (UUT complication rate 96.3%). Only the latter group was studied for long-term (mean 9.3 years) evaluation of the UUT and renal function. A temporary vesicostomy was the primary treatment in 25 patients. Indications for temporary diversion were very young age and/or low birth weight, severe and bilateral UUT complications, and severe renal damage. All the other patients were treated by primary endoscopic valve fulguration. After removal of the lower urinary tract obstruction, vesicorenal reflux (VRR) resolved spontaneously or was ameliorated in 59.2% of the renal units. Spontaneous normalization or evident amelioration were found at long-term follow-up in nearly 70% of dilated, non-refluxing ureters. Ureteral reimplantation was performed on 41 of the 202 dilated or refluxing ureters (surgical rate 20.3%). The surgical failure rate requiring reoperation was 5% (2/41). The prerequisite for successful reimplantation was a large-capacity, stable, and compliant bladder. Ten nephroureterectomies were carried out for unilateral, massive VRR and renal dysplasia; 1 late nephrectomy was performed for arterial hypertension. The evolution of renal function showed statistically significant overall improvement, which was more evident in patients diagnosed and treated in the 1st month of life (P = 0.000) than in those treated between 1 and 12 months (P = 0.004) or after 1 year of age (P = 0.025). Renal function considerably improved in the vesicostomy group (P = 0.000). Thirteen patients (12.4%) are now either dead (2) or have end-stage renal disease (6) or chronic renal insufficiency evolving toward end-stage renal disease (5); 5 of these 13 were treated by vesicostomy in the first days or months of life, and at presentation the glomerular filtration rate (GFR) was less than 25 ml/min . 1.73 m(2). Determination of basic GFR and, even more, functional renal reserve is relevant in predicting the long-term evolution. In the author's opinion, vesicostomy is the procedure of choice in very ill newborns or infants. Aggressive management with early surgical reconstruction is rarely justified, because frequently UUT complications resolve spontaneously or clearly improve, and their surgical treatment has limited and very precise indications.

The appropriateness of use and the clinical impact of micturating cystourethrography in paediatric practice

STUDY OBJECTIVE

To determine the appropriateness of use and the clinical impact of micturating cystourethrography (MCU) in paediatric practice.

DESIGN

Retrospective medical record review.

SETTING

A major teaching children's hospital in the Trent region.

PATIENTS

Consecutive sample of 120 children undergoing MCU during 1991-1992, identified from the radiology records.

MAIN OUTCOME MEASURES

The referring clinician's reasons for requesting an MCU; the clinical management plan pursued before and after the MCU, and the change in management initiated by the result of the examination; the appropriateness of use of the test, as determined by the presence or absence of a valid indication for MCU in the specific clinical situation.

RESULTS

The change in patient management attributable to the MCU result could be categorized as: no change (19%); decision to end the imaging investigation of the patient (33%); decision to end all investigations, and prophylactic or therapeutic interventions (16%); decision to discontinue chemoprophylaxis (2%); decision to end the imaging investigation and introduce chemoprophylaxis and follow-up for bacteriuria (6%); decision to continue the imaging investigation and introduce chemoprophylaxis and follow-up for bacteriuria (13%); and decision to operate or help in planning the surgical treatment required (11%). Inappropriate use of the test was observed in 20% of the cases.

CONCLUSIONS

This study provides a basis for understanding the use of MCU in paediatric practice. The findings that 19% of the cystourethrograms had no appreciable effect, and that 20% of the examinations were used inappropriately show the need for increased effort to minimize overuse of the test.

Prenatally detected posterior urethral valves: is gestational age at detection a predictor of outcome?

Between 1982 and 1992, 67 boys with posterior urethral valves were managed at our hospital, including 32 (48%) in whom the condition was detected prenatally. We examined the relationship between gestational age at detection and outcome at a median followup of 3.9 years (range 4 months to 10 years). Detection at or before 24 weeks of gestation predicted a poor outcome with 9 of 17 patients (53%) dead or in chronic renal failure at followup. Of the cases detected later in pregnancy only 1 had a poor outcome (p = 0.01). All of the cases detected after 24 weeks of gestation had had normal second trimester scans. Growth parameters for boys in the early and late detection groups were not statistically different. However, there was a significant association between renal failure and growth with 67% versus 14% having heights less than the 3rd percentile (p = 0.05). Respiratory distress at birth predicted a poor outcome, while the presence of palpable abdominal abnormalities or vesicoureteral reflux failed to predict outcome.

Cloacal anomalies: role of vesicostomy

The purpose of this report is to discuss the use of vesicostomy in the treatment of cloacal anomalies. In 4 years, the authors have performed primary reconstruction in four children who had cloacal anomalies. Three children had hydrocolpos, which in two cases failed to decompress with tube vaginostomy or clean intermittent catheterization. In both cases, cutaneous vesicostomy effectively prevented urinary sepsis, which allowed the children to thrive before definitive reconstruction was performed. Vesicostomy is technically simple to perform and is easily reversed without loss of bladder volume. Further, it lends itself well to definitive reconstruction of cloacal anomalies.

The operative management of posterior urethral valves

The surgical management of posterior urethral valves remains controversial. To examine the effects and results of operative treatment in boys with proven posterior urethral valves, a retrospective study was undertaken. The case records of 33 male children who presented with posterior urethral valves over a 10-year period were reviewed. Two patients died prior to definitive treatment and one died postoperatively. Following resuscitation and diagnostic procedures, the remaining patients had eradication of the posterior urethral valves by electrothermic fulguration. In 14 patients this was performed using the Innes-Williams diathermy hook under control of contrast enhanced radiography. In 16 patients the valves were fulgurated under direct cystoscopic visualization. All surviving patients had an uneventful postoperative recovery. However, of those undergoing cystoscopic fulguration, four developed symptomatic urethral strictures necessitating repeat cystoscopy and urethral dilatation. No cases developed strictures following the use of the diathermy hook. One patient from each treatment group developed dribbling. The Innes-Williams diathermy hook has been proven to be a safe, simple, and inexpensive technique. This has specific application in the neonate and small infant where cystoscopy poses technical problems because of anatomic size and where potentially traumatic urethral instrumentation should be avoided.