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A solitary functioning renal unit in high anorectal malformation may harbor anomalies in the upper/lower urinary tract that further compromise renal function and accelerate hyperfiltration injury. We aimed to analyze the clinical course, management, and outcome of children with a solitary renal unit and high anorectal malformation.
A cohort of solitary renal units in anorectal malformation managed between 2000 and 2015 with a defined protocol at a pediatric nephro-urology clinic are included in the study. Investigations and management were individualized according to issues in the agenetic/dysplastic unit, solitary functioning unit, or bladder-urethra. Clinical details, management, and outcome were analyzed.
Of 53 cases of high anorectal malformation with urologic anomalies, 17 (32%) had single kidneys. Majority (10/17, 59%) had another complicating urinary tract anomaly, four being uremic at presentation. Nearly half had multiple urinary infections including epididymo-orchitis unrelated to the rectourinary fistula and warranted additional stoma (bowel/urinary) or other urinary tract surgery. At a mean follow-up of 70 months, majority (14/17, 82%) have a preserved solitary renoureteric unit while the remaining three await renal replacement therapy.
Solitary functioning renal units associated with high anorectal malformation in children need meticulous investigation and surveillance to facilitate renal preservation. The implications of the associated rectourinary fistula, vesicoureteral reflux, urinary infections including epididymo-orchitis, and other urinary tract anomalies on the conventional surgical management are illustrated.
Unilateral renal agenesis is a common associated urinary tract anomaly in high anorectal malformation. The remnant solitary functioning kidney with an intrinsic potential for hyperfiltration injury may also have varying degrees of congenital or acquired, structural, or functional affliction that compromise renal parenchymal function. Lower urinary tract factors including neurovesical malfunction and contamination from rectourinary fistula further complicate the issue. We present a critical analysis of the clinical course, management dilemmas, and outcome of a cohort of solitary renal units in high anorectal malformation.
All cases of high anorectal malformation with a solitary functioning renal unit managed and followed up at a multidisciplinary pediatric nephro-urology clinic of a tertiary teaching hospital according to a protocol between 2000 and 2015 were included in the study. After a routine ultrasound confirmed the solitary renal unit, they were placed on antibiotic uroprophylaxis. A voiding cystourethrogram was carried out either during the distal cologram study or in the interim to detect vesicoureteral reflux and confirm bladder evacuation. A renal cortical scintigraphy (dimercaptosuccinic acid) evaluated the baseline parenchymal reserve and prenatal scarring/hypodysplasia. In case of urinary tract dilatation, a diuretic renogram (diethylene triamine pentaacetic acid) with a bladder catheter in situ was obtained to rule out obstruction. A panel of biochemical tests (serum creatinine, venous blood gas-bicarbonate, pH, and urinary microalbumin) evaluated renal status and the need for adjuvant renoprotective medications (calcium, bicarbonate, alpha calcidiol, and angiotensin-converting-enzyme inhibitors). Additional investigations (e.g., magnetic resonance imaging and urodynamic studies in neurovesical dysfunction) were conducted when indicated. Specific surveillance of a solitary renal unit at follow-up included tracking of hypertension, annual renal length for compensatory hypertrophy, and quantitative urinary microalbumin estimation. The management and follow-up was individualized according to the structural and functional pathology.
This is a retrospective review of case records and follow-up evaluation with patient recall. Age at diagnosis of urinary malformation, sex, birth weight, consanguinity, details of antenatal diagnosis, and associated anomalies (cardiac, genital, sacral spinal) were noted. Clinical presentation, baseline investigations including biochemistry, imaging, and serial observations of these were studied. Details of clinical course, especially urinary tract infections (VUR), medical and surgical management (creation and closure of urinary and bowel stoma, additional urinary tract surgical interventions), and outcome of the urinary tract malformation were collated and analyzed.
Table 1 details the clinical profile and management of the cases. Of 95 cases of high anorectal malformation managed during this period, 53 (56%) had associated genitourinary anomalies. Out of 53 patients, 17 (32%) had a solitary functioning renoureteric unit. All but one were males, all were born at term with an average weight of 2.4 kg. Out of 17 cases, 3 (18%) were born to consanguineous parents. Antenatal anomaly scans were either not available or failed to detect the solitary kidney. Seven cases were born at this center and ten elsewhere; six of the latter ten cases were transferred and managed here from the neonatal period while four reported later (4–108 mos). The diagnosis of a solitary renal unit was made at birth/during infancy in 14/17 (82%) and later in 3/17 (18%). Thus, 13/17 (76%) cases were on our management protocol from the neonatal period onward.
The serum creatinine at presentation was normal in 13/17 (76%); 3/4 cases with elevated levels had presented later than 4 months of age. A similar proportion had right or left agenesis on ultrasonography. Most such renal units were structurally undetectable; three were cystic-hypoplastic while three others had dilated ureters; the latter had high-grade vesicoureteral reflux. In the solitary functioning units, 6/17 (35%) had hydroureteronephrosis, and one had a hypodysplastic kidney too. Significant urological abnormalities were noted in 10/17 (59%) including high-grade vesicoureteral reflux, ureterovesical junction (UVJ) obstruction, anterior urethral hypoplasia, and neurovesical dysfunction. After initial stabilization, the renal cortical scan confirmed poor renal parenchymal function in the solitary unit in 3/17 (18%); the rest, including one with acute renal failure (Case 2), had preserved function.
The distal cologram showed rectourinary fistula in 12, rectovaginal fistula in the single female in this series, and no fistula in the rest four. The twelve fistula were four each in vesical, prostatic, and bulbar locations; the higher fistulas were wider with the vesical being the widest. A variety of associated anomalies were noted in this cohort, both of VACTERL (8/17) and non-VACTERL (2/17) nature.
Despite uroprophylaxis, 7/17 (41%) cases had multiple episodes of urinary tract infections. Three had unilateral epididymo-orchitis ipsilateral to the side of the agenesis, and one of these (Case 11) was complicated with a scrotal abscess. The microbiological flora in majority of the urine culture consisted of enteric Gram-negative bacteria; a third of these grew multidrug resistant species in the second or third episode and required escalation of antimicrobial therapy. Two had an invasive bloodstream candidal infection during these episodes.
The initial choice of colostomy was sigmoid loop (8/17), sigmoid divided (7/17), or a transverse loop (2/17) stoma; three of these were revised. Stomal resiting from sigmoid loop to transverse divided was done in two (Case 1, 2) to accommodate a left ureterostomy for UVJ obstruction (Case 2) or during abdominoperineal pull through for a short distal rectosigmoid length (Case 1); both had multiple breakthrough urinary infections even after disconnection of the rectourinary communication at anorectoplasty. Similarly, a poorly constructed loop stoma was revised to divided in one with recalcitrant urinary infection (Case 5). Imaging and ureteroscopy identified two with severely hypoplastic urethra [Figure 1] that accomodated a number 7.5 Fr. Cystoscope only after dilatation with filiform dilators. Two others had iatrogenic strictures at the prostatic and bulbar urethral level - postoperative or postinstrumentation. While three of these four urethral lesions were amenable to multiple scheduled dilatation, one required a perineal urethroplasty. Five cases were managed with urinary stomas - one temporary percutaneous nephrostomy and then a left Sober's en-Y ureterostomy for a UVJ obstruction, one vesicostomy and four temporary suprapubic tube cystostomy during anorectoplasty for the management of various urethral issues.
Other urinary tract surgical interventions included retrieval of calculi from the ureter, bladder and anterior urethra, ureterectomy, nephroureterectomy, ureteric reimplantation, scrotal debridement, and urethral dilatations.
The total follow-up ranged from 11 to 123 mos (mean - 70 mos). The follow-up after anorectoplasty is 6–115 mos (mean - 56 mos). All urinary and bowel stomas have been closed after completion of reconstructive procedures. The majority (14/17, 82%) are well, asymptomatic, and off uroprophylaxis; 13/14 (93%) cases have a nonobstructed, nonrefluxing solitary functioning renal unit while one with neurovesical dysfunction (Case 4) is on clean intermittent catheterization (CIC) to evacuate the bladder reliably. All 14 cases are normotensive and have normal urinary microalbumin; the renal units show the anticipated compensatory hypertrophy and increased renal length. Out of 17 cases, 3 (18%) have chronic renal failure (CRF), are on CIC, and await renal replacement therapy.
Urinary tract anomalies are the most common associated anomaly in anorectal malformation and feature in 26%–52% of several large series. Unilateral renal agenesis and vesicoureteral reflux comprise the majority of the urinary tract anomalies associated with high anorectal malformation. A solitary, normally functioning renoureteric units are compatible with life; however, a third develop renal injury by 10–15 years of age[4,5] and 20%–50% decompensate to renal failure at adolescence/adulthood due to glomerular hyperfiltration-glomerulosclerosis. However, in the setting of urinary tract obstruction/vesicoureteral reflux in the unit, a vicious mix of infection-reflux nephropathy-scarring culminates in CRF in early childhood. Among the gamut of anorectal malformation, the high anorectal malformation in males is at maximal risk of urinary infection because of multiple factors,[6,7] including ipsilateral congenital anomalies of the kidney and urinary tract.[5,8] This case series illustrates several management dilemmas; the rationale of management and lessons learned thereof. To the best of our knowledge, there has been no published report that addresses this particular subgroup of patients.
It is surprising that anomaly scans did not detect the unilateral renal agenesis or cystic renal masses and testifies to the operator dependence of the investigation. The male preponderance (16/17) reflects the more common occurrence of high anorectal malformation in males. Similarly, such males are more likely to have upper urinary tract anomaly, especially renal agenesis.[6,7] On close analysis, what mattered in the management was not the age at presentation at this referral center, but whether the solitary renal status and accompanying urinary flow obstruction/vesicoureteral reflux are diagnosed in the neonatal period and necessary management initiated, for example, distal stomal washes, uroprophylaxis, expedient management of interim urinary infection, and medical therapy for renal dysfunction.
The agenetic/dysplastic renoureteric unit can be cryptic in presentation. The accompanying high-grade vesicoureteral reflux into its dilated ureter is a source of infection and nidus for calculi formation (Case 1); an ectopic ureteral opening into the posterior urethra (Case 5) or vas deferens adds to the morbidity. Anomalies in the solitary functioning unit (hypodysplasia, vesicoureteral reflux, pelviureteric, or UVJ obstruction) and the bladder outflow/urethra (neurovesical dysfunction-congenital or iatrogenic, urethral hypoplasia, urethral injury-stricture) are crucial in determining the clinical course and mandate individualized management. The combination of a single kidney with troublesome vesicoureteral reflux in anorectal malformation is relatively common and must be closely watched to prevent renal deterioration.[10,11] A higher rectourinary fistula is linked to a greater risk of infection in two ways – first, it is invariably wider and more contaminating; second, it is associated with greater neurovesical dysfunction. The described protocol for solitary renoureteric units incorporating directed imaging and cystoscopy clarifies the pathological anatomy at the earliest and ensures optimal continued surveillance, especially in the 1st year of life during renal growth. Like others, we observed that a normal renal length at birth and the anticipated compensatory hypertrophy was accompanied by preserved renal function.
Unlike rectovestibular/rectovaginal fistulas in females, rectourinary fistulas predispose the male urinary tract to a relatively higher risk of infection. The common embryogenesis of mesonephric duct derivatives explains the association between structural facts such as ipsilateral renal agenesis, ectopic opening of verumontanum near the bladder neck, abnormal opening of ureter into vas and their functional implications of congenital neurovesical dysfunction, vesicoureteral reflux, and urethrovasal reflux. The proximity of the rectourinary fistulous and vasal opening in the posterior urethra and surgical instrumentation around the veru and bladder neck during surgery for anorectal malformation with prostatic or vesical fistulas adds to the risk of an epididymo-orchitis. Recurrent epididymitis in a patient with anorectal malformation warrants a comprehensive urologic investigation; it is often coexistent with or predates an ascending VUR into the solitary renal unit.
Urologic diagnosis in high defects assumes an equal priority as the decision for and siting of the colostomy in the neonatal period. In general, a temporary urinary diversion, tubed or otherwise, may be anticipated in the presence of a grossly dilated solitary renoureteric system, whether refluxing or obstructed. Here, the siting of the bowel and urinary diversion can be planned to be as apart from each other as feasible so as to avoid fecal contamination. Else, resiting of colostomy would be required to accommodate a later urinary stoma (Case 1, 2). In our practice, a well-constructed spur of a loop stoma effectively diverts the fecal stream. In persistent urinary infection, we have converted a loop into a divided stoma. Later in the series, we have electively performed divided stomas in all anorectal malformations with a single kidney at the outset. Interestingly, recent studies have indicated that loop stomas do not necessarily confer an increased risk of urinary infection than divided stomas. Despite precautions and rectourinary disconnection at anorectoplasty, a quarter of patients had ureteral and urethral issues that complicated the course and prompted additional surgical interventions to arrest urinary infections and preserve renal function.
When the solitary renoureteric unit and the vesicourethral channel were normal, the timetable of managing the anorectal malformation was as expected. However, in those with compromised solitary renoureteric system, either due to anomalies in the agenetic side or the functioning side or the bladder outflow-urethra, the number of stomas/surgical interventions was increased, and stoma closure was delayed. Postoperatively, constipation and bowel bladder dysfunction are important triggers in initiating an urinary infection; in solitary renal units, the risk of parenchymal loss was real with every such episode. In high anorectal malformation with neurovesical dysfunction, strict CIC and bowel enemas were helpful. Several cases in this cohort are entering the second decade of life and would need continued lifelong surveillance to identify evolving hyperfiltration injury.
The presence of a solitary functioning renal unit has far reaching implications in the management of high anorectal malformation in children, especially in males. The investigations are geared to decipher the pathological anatomy of the entire upper and lower urinary tract from the neonatal period so as to facilitate strict surveillance and ensure renal parenchymal preservation. The special significance of rectourinary fistula and recurrent epididymo-orchitis is elucidated. The impact of each of these factors on treatment planning and surgical management must be understood to avoid misadventures.
There are no conflicts of interest.