A comparison of clinical outcomes of acute testicular torsion between prepubertal and postpubertal males.

SHORT INTRODUCTION/BACKGROUND: Surgical intervention for acute testicular torsion can require either orchiopexy or orchiectomy. The decision of which surgery to perform is dependant on the amount of time that the testicle experienced ischemia and the viability of the testicle after reperfusion. OBJECTIVE: It is hypothesized that (1) there is a difference in orchiectomy and orchiopexy rates between prepubertal and postpubertal males with acute testicular torsion and (2) presenting symptoms may vary between the two age groups as prepubertal males may present with atypical symptoms, which could result in delayed presentation and diagnosis. STUDY DESIGN: A retrospective chart review was conducted on pediatric patients who were diagnosed with acute testicular torsion between June 2010 and August 2017. Demographic and clinical characteristics were extracted: age, ethnicity, referral pattern, primary insurance status, symptoms at presentation, prior history of ipsilateral testicular pain or intermittent torsion, recent trauma to genitalia, duration of symptoms (hours), gradual vs. acute onset of symptoms, time/weekday/season at presentation, and time interval from arrival at the study institution to surgical intervention (minutes). Patients were categorized into two groups: prepubertal group (age 1-12 years) and postpubertal group (age 13-18 years). Statistical analyses were performed using R, version 3.3.1. RESULTS: Ninety-one patients were included in the study. The overall orchiectomy rate was 30.8%. More prepubertal males underwent orchiectomy than postpubertal males (42.4% vs. 24.1%, respectively). Prepubertal males were more likely to present with abdominal pain than postpubertal males (27.3% vs. 10.3%, respectively). Those who underwent orchiectomy were more likely to present with longer duration of symptoms, testicular swelling, and abdominal pain than those who underwent orchiopexy. The risk of orchiectomy decreased by 14% per 1-year increase in age (odds ratio [OR]: 0.86, 95% confidence interval [CI]: 0.94-1.00, p = .009). A steady decline in the proportion of patients undergoing orchiectomy was seen from 1 to 12 years of age. DISCUSSION: This study found that prepubertal males are at higher risk for orchiectomy than postpubertal males. The risk of orchiectomy decreases by 14-16% per 1-year increase in age. Prepubertal males are more likely to present with atypical symptoms and delayed presentation and diagnosis, leading to delayed surgical intervention. It is important for providers to perform a genital examination in prepubertal males who present with abdominal pain to rule out acute testicular torsion. Patients presenting with longer duration of symptoms, testicular swelling, and abdominal pain are at higher risk for orchiectomy. No correlation was found between orchiectomy rate and ethnicity, referral status, primary insurance status, and time/weekday/season at presentation. CONCLUSION: Among patients presenting to a tertiary pediatric hospital with acute testicular torsion, prepubertal males (younger than 12 years) are at higher risk for orchiectomy than postpubertal males. Prepubertal males are more likely to present with atypical symptoms which results in delayed presentation and diagnosis, leading to delayed in surgical intervention.

The presence or absence of an impalpable testis can be predicted from clinical observations alone.

OBJECTIVE: To evaluate, in a prospective study, the accuracy of predicting the presence or absence of unilateral or bilateral impalpable testes from a clinical examination, particularly whether the contralateral descended testis (CDT) is hypertrophied. PATIENTS AND METHODS: Whether the ipsilateral scrotal appendages were palpable, and the size of the CDT, were determined before surgery in a series of patients, and compared with age-matched controls. Between 1992 and 2000, 100 impalpable testes in 86 consecutive patients (mean age at orchidopexy 45 months, range 6-223; 66% <36 months) were evaluated and treated. In addition to the presence or absence of palpable ipsilateral scrotal appendages, the size of the CDT, when present, and the intraoperative findings were recorded. Logistic regression analysis was used to model the probability of the presence or absence of the testis, as determined by the preoperative clinical findings alone. RESULTS: Of the 86 testes that were located at surgery, 50 (58%) were intracanalicular, 28 (32%) intra-abdominal and the remainder (10%) were in the superficial inguinal pouch. Of 13 patients with the 'vanishing testis syndrome', the atrophic testicle was intracanalicular in nine, in the upper scrotum in three and intra-abdominal in only one. All viable testes were successfully relocated in the scrotum, with one atrophic after surgery. The positive predictive value (PPV, with 95% confidence interval) of a testis being present when the ipsilateral appendages were palpable and the CDT was not hypertrophied was 0.93 (0.83-0.97). Conversely, the PPV of the impalpable testis being absent when the appendages were impalpable and the CDT was hypertrophied was 0.95 (0.64-0.99). CONCLUSION: When evaluating and surgically treating impalpable testes, the presence of palpable ipsilateral scrotal appendages and a CDT with no hypertrophy is associated with a 93% likelihood of discovering a testis that can be successfully relocated to the scrotum. Conversely, when the ipsilateral scrotal appendages cannot be palpated and the CDT is hypertrophied, there is a 96% probability that the impalpable testis is absent (vanishing testis syndrome). This readily available information may be valuable in preoperative counselling and planning.

The normal kidney growth rate during year 1 of life is variable and age dependent.

PURPOSE: The concept of normal contralateral kidney growth rate was introduced as a parameter to consider in conjunction with others in the evaluation of unilateral hydronephrosis in asymptomatic neonates and infants. Historically measurements of renal size obtained at different times from different patients have been relied on to construct normal renal growth charts. We report normal kidney growth rates in year 1 of life derived from interval ultrasound measurements of renal size in the same newborns and infants longitudinally with time. MATERIALS AND METHODS: We reviewed 333 normal renal ultrasound studies performed between 1991 and 1995 in 55 patients during year 1 of life. These longitudinal measurements were made bilaterally 2 to 8 times (median 3) per patient. Growth curve models that consider random patient effects were used to estimate the mean growth curve and ascertain its form. We also reviewed an additional 91 ultrasound studies in 10 patients with myelomeningocele without hydronephrosis or reflux. We analyzed the kidney growth rate in a similar manner and compared the results with those in the normal patients. RESULTS: Analysis of the normal cases revealed a changing growth rate during year 1 of life estimated to be 3.1 mm. per month at birth, decreasing gradually during the first 7 months of life to 0.25 mm. per month and remaining constant thereafter (p = 0.0064). Mean kidney size at birth was estimated to be 42.8 mm. (95% confidence limits 27.0 to 58.5). At age 7 months mean size was 60.7 mm. (95% confidence limits 40.1 to 81.3). CONCLUSIONS: These data demonstrate that normal kidney growth is age dependent. A rapid but slowly decreasing growth rate during the first 7 months of life is followed by a more constant and lower rate. The data also suggest that unusually rapid growth, such as that which may occur in the normal contralateral kidney in unilateral obstruction, may also be age dependent, exceeding 5.0 mm. per month during the first 7 months of life and 2.0 mm. per month thereafter.

Incidence and natural history of contralateral vesicoureteral reflux in patients presenting with unilateral disease.

PURPOSE: The new onset of contralateral vesicoureteral reflux after the surgical correction of unilateral disease has been well documented and it is attributed to the surgical procedure. However, to our knowledge the spontaneous development of contralateral reflux in patients treated nonoperatively for unilateral disease has not been documented previously. We evaluated the incidence and natural history of contralateral reflux in children presenting with initially unilateral disease. MATERIALS AND METHODS: We reviewed the records of 130 girls and 13 boys with a mean age of 29.1 months presenting with primary unilateral reflux between 1983 and 1996. The grade of and time to new onset contralateral reflux were noted. Whereas the initial radiological diagnosis relied on contrast voiding cystourethrography, followup evaluation included contrast and radionuclide voiding cystourethrography. The upper tracts were assessed by ultrasound and/or excretory urography, and cortical renal scans were performed selectively. RESULTS: Patients were followed a mean of 32.2 months (range 4.6 to 147). Of the 143 patients 135 presented with a febrile urinary tract infection, and in 14 reflux was associated with a ureteral duplication anomaly. At presentation reflux was grade I or II in 110 patients, grade III in 26 and grade IV or V in 6. Followup voiding cystourethrography in the 143 patients revealed new onset contralateral vesicoureteral reflux in 47 (33%). Mean time to the appearance of new onset reflux was 17.6 months (range 0.6 to 91.8). Reflux was grades I to III in 22, 21 and 4 patients, respectively. Contralateral reflux resolved spontaneously in 19 cases (40%), persists in an additional 16 (34%) and was surgically corrected at ipsilateral ureteroneocystostomy in the remaining 12 (26%). Contralateral renal scarring was noted in 3 cases (6%). CONCLUSIONS: New onset contralateral vesicoureteral reflux developed in a third of the patients initially diagnosed with unilateral disease while they were followed nonoperatively. This finding suggests that contralateral reflux after the surgical correction of unilateral disease may not always be associated with the surgical procedure. It may be a manifestation of the natural history of unilateral reflux.

Compensatory renal growth in the solitary kidneys of Danforth mice with genetic renal agenesis.

PURPOSE: Previously the upper urinary tract anatomy has been characterized in Danforth mice spontaneous murine mutation. This mutation results in unilateral renal agenesis in 30% of the heterozygous offspring. Whether compensatory renal growth occurs in the remaining solitary kidney was assessed. MATERIALS AND METHODS: Heterozygous pairs of Danforth mice were mated. Of 99 kidneys recovered from adult offspring (8 weeks old) 41 were fixed in Bouin's solution, weighed, sectioned at 8 microm., stained and prepared for morphometry. An additional 6 kidneys recovered near term (gestational day 18) were processed in the same fashion. The kidneys from the mice without the mutation served as controls. Morphometric analyses were performed using computer software. The size and the distribution of glomeruli were studied. RESULTS: The kidney-to-body weight ratio in the mice with 2 kidneys varied between 1.286 and 2.198 (mean 1.603 +/- 0.33). There were 9 solitary kidneys and their weight x 2/body weight ratio varied between 1.744 and 3.779 (mean 2.9583 +/- 0.724). The differences between these 2 groups were statistically significant (p = 0.003). In addition, the mean cross sectional areas in solitary kidney glomeruli was 13.2% greater than those in bilateral kidneys. CONCLUSIONS: Previously described models of compensatory renal growth relied on surgically inducing varying degrees of renal ablation in intact animals with 2 kidneys, which introduced numerous variables in the study of a complex problem. The results demonstrate that the naturally occurring solitary kidneys of the Danforth mice undergo compensatory renal growth. Furthermore, this growth is initiated early in utero. The lack of anesthetic and surgical manipulation may make this an attractive, reliable and readily available model for the study of compensatory renal, including in utero, growth.

Ectopia of both moieties of ureteral duplication anomalies.

The upper pole ureter of a duplication anomaly can be orthotopic or associated with an ectopic insertion, a ureterocele, or even ureteropelvic junction obstruction. The lower pole ureter may terminate orthotopically or laterally on the trigone, resulting in varying grades of vesicoureteral reflux. It can also be associated with lower pole ureteropelvic junction obstruction. In this report, we describe 3 patients with ureteral duplication anomalies in whom both upper and lower ureters terminate ectopically outside the bladder. The mode of presentation, the diagnosis, and the management of this rare anomaly are described. In addition, a hypothesis is advanced to help understand the embryologic pathophysiology.

Ten years of experience with isolated urachal anomalies in children.

PURPOSE: The embryological and anatomical features of urachal anomalies have been well defined. Because of the variable clinical presentation, uniform guidelines for evaluation and treatment are lacking. In an attempt to establish a cost-effective approach leading to a favorable outcome, we reviewed the experience with urachal anomalies at a single institution in a 10-year period. MATERIALS AND METHODS: We reviewed the medical records and radiological studies of 12 boys and 9 girls newborn to 17 years old at presentation who were treated for a urachal anomaly. Diagnostic evaluation included voiding cystourethrography in 14 cases, ultrasound in 8, sinography in 7 and computerized tomography in 4. RESULTS: The 4 variants of urachal anomalies included a urachal sinus in 9 patients (43%), urachal cyst in 9 (43%), patent urachus in 2 (10%) and urachal diverticulum in 1 (4%). Treatment involved initial excision in 13 cases (61%) and secondary excision in 8 (39%). Staphylococcus aureus was the predominant organism recovered. CONCLUSIONS: Because of the variable presentation, the diagnosis of a urachal anomaly can be difficult. Our experience suggests that a cost-effective diagnostic approach can be developed based on the initial clinical evaluation. Whereas ultrasound is indicated when a urachal cyst or abscess is suspected on the initial study, sinography is the study of choice in the remainder of cases. A voiding cystourethrogram may not be required in view of the fact that none of the patients studied had an additional associated urinary tract anomaly.

Indications for and outcomes of clean intermittent catheterization in children with normal genital sensation.

PURPOSE: Clean intermittent catheterization is generally accepted by parents and children with neurogenic bladder. We analyzed the indications for and feasibility of clean intermittent catheterization in children with normal genital sensation. MATERIALS AND METHODS: We reviewed the records of 2 girls and 15 boys 15 months to 15 years old (mean age 8 years) on clean intermittent catheterization with normal genital sensation. Indications for clean intermittent catheterization were urinary retention and poor urodynamic compliance with or without hydronephrosis. Parents evaluated the protocol via a questionnaire and the children were studied with age appropriate standard instruments to assess the consequences of clean intermittent catheterization on psychological development. RESULTS: There were no medical complications related to clean intermittent catheterization. Four of the 7 children with urinary retention and 7 of the 10 with poor bladder compliance continued the protocol. There was no difference in the results of psychological testing for patients who had success or failure (mean followup 5 years). Parent and patient comfort levels were most important for the success of clean intermittent catheterization. CONCLUSIONS: Our results show that clean intermittent catheterization is feasible in children with normal genital sensation but successful in only two-thirds.

Common sheath reimplantation yields excellent results in the treatment of vesicoureteral reflux in duplicated collecting systems.

PURPOSE: We evaluated our 10-year experience with the surgical treatment of vesicoureteral reflux in uncomplicated duplicated collecting systems. MATERIALS AND METHODS: Between 1984 and 1994, 54 refluxing renal units (8 bilateral) in 37 female and 9 male patients required surgery. Patient age ranged from 7 months to 17 years (average 4.9 at surgery). Postoperative followup (average 14.2 months) included voiding cystourethrography and renal sonography or excretory urography. RESULTS: Common sheath ureteral reimplantation via an intravesical approach was performed in 48 of the 54 refluxing renal units. Of the remaining 6 renal units detrussorrhaphy was performed in 4, and ureteroureterostomy combined with ureteral reimplantation and partial lower pole nephrectomy were done in 1 each. Two treated renal units had persistent postoperative vesicoureteral reflux, which resolved after subureteral polytetrafluoroethylene (Teflon) injection. No renal had postoperative hydronephrosis. Contralateral reflux was identified in 1 patient who underwent unilateral reimplantation. Our overall success rate was 96% for the surgical correction of vesicoureteral reflux in uncomplicated duplicated collecting systems. Common sheath reimplantation had a 98% success rate. CONCLUSIONS: Although a duplicated collecting system increases the risk for surgical treatment, the presence of a duplication anomaly does not adversely affect surgical outcome. Modifications of procedures commonly performed in the surgical treatment of single system reflux to accommodate common sheath reimplantation have excellent surgical results with minimal morbidity.

The Malone antegrade colonic enema enhances the quality of life in children undergoing urological incontinence procedures.

PURPOSE: Functional alterations of the gastrointestinal and genitourinary tracts, and physical limitations in children with spina bifida, imperforate anus and spinal cord injury challenge the ability to have independent fecal and urinary continence. Urologists have successfully helped these patients achieve urinary continence. We report our experience with the antegrade colonic enema procedure, which allows select individuals to achieve continence of stool, enhancing quality of life. MATERIALS AND METHODS: Since December 1992, 18 antegrade colonic enema procedures were performed in 12 female and 6 male patients 5 to 31 years old of whom 14 had spina bifida, 2 had imperforate anus and 2 had spinal cord injury. Simultaneous urological continence procedures were performed in 8 patients, including appendicovesicostomy in 4, augmentation cystoplasty in 2 and augmentation cystoplasty plus an ileal Mitrofanoff procedure in 2. Four patients previously underwent urological reconstruction. RESULTS: In 24 months of followup (average 6.6) all patients with a functioning stoma remained continent of stool and 17 were continent of urine. Complications related to the antegrade colonic enema procedure occurred in 4 children (22%) of whom 3 required further surgery. Three patients (17%) had minor stomal stenosis. CONCLUSIONS: The antegrade colonic enema procedure is easily performed and it should be considered for any child with significant physical limitations and/or refractory fecal incontinence before urological continence promoting procedures are done.

Long-term outcome of kidneys with initially poor drainage or no drainage following pyeloplasty.

Pyeloplasty for congenital ureteropelvic junction (UPJ) obstruction enjoys a 90-95% success rate. Although treatment of the failed pyeloplasty has been addressed in the literature, management of the poorly draining or nondraining renal unit in the immediate postoperative period has not received any attention. For this purpose the medical records of 33 consecutive children (37 renal units) treated by dismembered pyeloplasty between 1986 and 1992 were reviewed. All of our pyeloplasties were stented and urine was diverted via a nephrostomy tube. All patients underwent a nephrostogram following stent removal 1 week postoperatively. These studies showed poor drainage, or no, across the newly reconstructed anastomosis in 7 of 37 renal units (19%). The ages of these 4 boys and 3 girls at the time of pyeloplasty ranged between 7 weeks and 5 years (mean 22 months). In four patients, good drainage occurred without intervention by 2-4 weeks postoperation. In two patients, percutaneous balloon dilation of the anastomosis via the intraoperatively placed nephrostomy tube was required at 3 and 6 weeks, respectively. The remaining patient failed percutaneous dilation, necessitating a ureterocalycostomy at 9 weeks following pyeloplasty. The long-term follow-up for the entire group of 33 children averaged 30 months and consisted of radionuclide diuresis renography in 84% of cases or intravenous pyelography in the remainder. All patients had excellent long-term outcomes as assessed by comparison of the postoperative studies with the baseline studies obtained preoperatively. Our results show that kidneys with initially poor drainage, or even no drainage, across the newly reconstructed anastomosis following pyeloplasty can be salvaged with an excellent long-term outcome comparable with that of the group with initially good drainage. In addition, intervention was necessary in only 43% of renal units with initial compromise and was facilitated by the intraoperatively placed nephrostomy tube. We recommend that percutaneous dilation be done at between 4 and 6 weeks postpyeloplasty, as the waiting period was long enough to allow for spontaneous improvement without precluding a successful outcome if drainage failed to occur. Ureterocalycostomy was rarely necessary.

Are modern imaging techniques over diagnosing ureteropelvic junction obstruction?

Since the widespread use of real-time ultrasonography in the early 1980s, ureteropelvic junction obstruction has been diagnosed at earlier ages and prenatally on a presumptive basis. However, substantial controversy exists over the diagnosis and treatment of ureteropelvic junction obstruction. We conducted an epidemiological study to determine if modern imaging techniques are leading to the over diagnosis of ureteropelvic junction obstruction. Records were collected retrospectively from 3 hospitals serving 2 adjacent counties to determine the number of pyeloplasties performed in 1970 to 1992. The 2 university hospitals and 1 large private hospital provide a wide variety of services and choice of urologists, and so it was assumed that most patients requiring pyeloplasty in the area would be captured. Of the 555 pyeloplasties 240 (43%) were performed on children 12 years old or younger. Logistic regression analysis revealed an overall increase of pyeloplasties per year of 56.8% in 23 years, which was not markedly different from the population growth in the area in the same period (49.3%). A statistically significant increase in the number of pyeloplasties performed in the first year of life was noted. This trend appeared to begin in 1981: 8 pyeloplasties were performed in the first year of life between 1970 and 1980 compared to 91 between 1981 and 1992. Pyeloplasties in children 1 to 6 years old increased with time at a much lower rate that was not statistically significant and the number of pyeloplasties decreased in those 7 to 12 years old. Therefore, it appears that modern imaging techniques are not leading to an over diagnosis of ureteropelvic junction obstruction but to detection of the disease at an earlier age.

The impact of prenatal sonography on the morbidity and outcome of patients with renal duplication anomalies.

Historically, most patients with a renal duplication anomaly associated with upper pole hydronephrosis underwent upper pole nephrectomy and partial ureterectomy. Prenatal sonography has resulted in increased recognition of these anomalies and, therefore, earlier urological referral and evaluation. We investigated whether as a result more upper pole moieties were preserved by performing alternative procedures, such as ureteroureterostomy. In addition, the impact on overall morbidity of the disease and its treatment is assessed. Since 1984, of 29 patients treated for ectopic ureter or ureterocele 13 presented initially with a diagnosis of prenatal hydronephrosis. Of these patients, 5 (38.5%) underwent a renal sparing procedure consisting of ureteroureterostomy in 4 and excision of ureterocele with common sheath ureteral reimplantation in 1. The remaining 8 patients underwent upper pole nephrectomy and partial ureterectomy for a nonfunctioning upper pole moiety. In contrast, of 16 patients who presented without having undergone prenatal sonography only 2 (12.5%) underwent a renal preserving procedure. Initial treatment in the remaining 14 patients was upper pole nephrectomy and partial ureterectomy. The average age at initial treatment in the prenatally detected group was 3 months, compared with 5 years in the other group. Only 1 of the 13 patients (8%) in the prenatally detected group had symptoms, whereas 14 of 16 in the other group (87.5%) presented with significant symptoms consisting of sepsis in 12, an abdominal mass in 1, urinary incontinence in 1, and an incidental diagnosis made during evaluation of an associated anomaly in 2. Although there is still controversy regarding the impact of prenatal detection of hydronephrosis on the preservation of renal function in patients with a single system, our results show a beneficial effect in patients with duplication anomalies. This was reflected in our ability to salvage the upper pole moieties 3 times more frequently than was previously possible with minimal morbidity. More importantly, the potential serious clinical manifestations of these duplication anomalies in later life were eliminated by virtue of early treatment.

Cloacal and urogenital abnormalities induced by etretinate in mice.

Etretinate, a synthetic retinoid, is a potent teratogen. It has previously been shown that acute exposure of gestational day 8 (equivalent to human week 4 post-fertilization) C57BL/6J mouse embryos to this retinoid results in a spectrum of abnormalities that are recognized as constituting caudal regression (dysgenesis). These defects, which include spina bifida, imperforate anus, genitourinary anomalies, omphalocele and limb anomalies, result from a major insult to the primitive streak, that is the gastrulation process. Developmental stages present early on gestational day 9 in mice represent the final stages during which the primitive streak contributes to the trunk of the embryo and, therefore, the last opportunity for abnormalities within the realm of caudal regression to be induced. In fact, acute etretinate exposure on gestational day 9 resulted in anal and urethral atresia, bladder and ureteral dilatation, and tail deficiencies as observed in 251 near-term fetuses in this study. To examine in further detail the gestational day 9 etretinate induced urogenital and anal abnormalities and their pathogenetic basis, analyses were conducted using scanning electron microscopy, light microscopy, antegrade cystourethrograms and a vital staining technique as early as 6 hours following maternal drug administration. It appears that diminution of the caudal cell populations, including those of and those surrounding the cloaca, at this critical stage of embryogenesis accounts for the observed phenotype. We propose that anal and urethral atresia temporally represents the end of the caudal regression (dysgenesis) syndrome.

Nonobstructive dilatation of upper urinary tract may later convert to obstruction.

We report on 5 babies found to have pyelocaliectasis or hydroureteronephrosis antenatally who were evaluated soon after birth because of persistent mild or moderate upper urinary tract dilatation. In each instance, vesicoureteral reflux was absent and the technetium-99m diethylenetriaminepentaacetic acid renal scan revealed good function in the ipsilateral kidney. Renogram curves, after furosemide, did not show an obstructed pattern. Indeed, allowing for the dilatation, the drainage patterns were thought to be normal. In each instance the patient represented or was found on follow-up to have increased dilatation. Renograms were then repeated, using the same radiopharmaceutical and dose of diuretic. An obstructive pattern was seen in each instance. These significant observations demonstrate that nonobstructive hydronephrosis, diagnosed prenatally, may later convert to obstruction at the ureteropelvic junction (UPJ) or in the juxtavesical ureter (UVJ). Thus, careful follow-up, for a period yet to be determined, is desirable in patients in whom the initial postnatal evaluation does not demonstrate obstruction by current criteria.

Unilateral renal agenesis may result from in utero regression of multicystic renal dysplasia.

Renal agenesis is generally thought to result from a lack of induction of the metanephric blastema by the ureteral bud, which may be secondary to ureteral bud maldevelopment and/or to a problem with the formation of the mesonephric duct. Multicystic dysplasia is thought to result from early ureteral obstruction as evidenced by the high frequency of associated proximal ureteral atresia. The recent obstetrical practice of large scale screening of large numbers of fetuses with sonography has resulted in a significant increase in the detection of this and other genitourinary anomalies. These findings have contributed to our understanding of the natural history of many of these malformations, resulting in ongoing reassessment and refinement of current management modalities. Thus, it is now well established that a significant number of multicystic dysplastic kidneys, initially detected in utero and followed postnatally, involute and disappear with time. We report the unequivocal presence of unilateral multicystic dysplasia detected during maternal sonography in 3 fetuses, which could not be seen on subsequent studies during the fetal or immediate postnatal period. To our knowledge, these cases constitute the first report of complete in utero regression of multicystic kidneys. This novel observation indicates that some cases of unilateral renal agenesis result from in utero regression of multicystic dysplastic kidneys. This phenomenon may explain the presence of an ipsilateral blind ending ureter found in some patients with unilateral renal agenesis. However, this infrequent observation does not explain all cases of renal agenesis. Thus, the etiology of renal agenesis remains multifactorial.

Heterotopic hindgut duplication: a cloacal remnant associated with exstrophy of the bladder.

Lower hindgut duplications, although very rare, usually present as a cystic mass located posterior to the rectum and confined to the pelvis. Hindgut duplications are often associated with genitourinary or spinal anomalies. We describe a neonate with a previously unreported heterotopic colonic duplication presenting as an exophytic perineal mass associated with classic bladder exstrophy. The embryonic significance of these anomalies is discussed.

Characterization of the upper urinary tract anatomy in the Danforth spontaneous murine mutation.

Absence or maldevelopment of the ureteral bud is thought to represent the final pathophysiological pathway resulting in renal anomalies ranging from agenesis to duplication. Little is known about the events preceding anomalous or absent ureteral bud formation. We describe the renal and ureteral anomalies found in a spontaneous murine mutation associated with a short tail: the Danforth or Sd mutation. Thirteen heterozygous pairs of mice were mated. Of 57 near-term progeny 40 had short tails. Microdissection revealed both kidneys and ureters in 35%, neither kidneys nor ureters in 27.5%, absence of the left kidney and ureter in 10%, absence of the right kidney and ureter in 7.5%, and absence of 1 or both kidneys associated with a blind-ending ureter in 20% of the mice. Scanning electron microscopy of gestational day 12 fetuses revealed unilateral or bilateral absence of the metanephros in some embryos, including some with a ureteral bud. Thus, primary absence of the metanephros may have a role in renal agenesis. Additional findings suggest that compensatory renal hypertrophy occurs in utero in the fetuses with unilateral renal agenesis. The morphological abnormalities involving the kidneys in the Sd mutation may represent an excellent model to study the pathophysiology of renal agenesis and mechanisms of normal renal development.