Pediatric Urologic Emergencies

Question 1

How often does prenatal sonography detect a significant fetal anomaly?

Answer 1

In 1% of pregnancies.

Question 2

Of fetal anomalies detected by prenatal sonography, how many of these are genitourinary, and what is the most common urologic abnormality?

Answer 2

25% are genitourinary.

Hydronephrosis is the most common urologic abnormality found on sonography, representing 50% of all genitourinary fetal anomalies.

Question 3

What is the differential diagnosis of bilateral hydronephrosis on prenatal sonography?

Answer 3

Vesicoureteral reflux (VUR), fetal ureteral folds, or megaureters. Posterior urethral valves (PUV) must also be considered in a male fetus, especially if there is evidence of a dilated bladder.

Question 4

What is the cause and significance of oligohydramnios?

Answer 4

Abnormal or deficient fetal kidneys will produce less urine, which leads to oligohydramnios. Therefore, a screening ultrasound evaluation of the fetal kidneys is reasonable if oligohydramnios is found. Oligohydramnios may also be caused by rupture of amniotic membranes, inadequate urine production, obstructive uropathy, or post-term gestation. Renal causes of oligohydramnios include renal agenesis or dysplasia, obstruction, or hypoperfusion of the kidneys. Oligohydramnios may lead to pulmonary hypoplasia. The second trimester is the most critical for fetal lung maturation.

Question 5

Which are potentially more dangerous: obstructive or non-obstructive lesions of the kidneys?

Answer 5

In association with hydronephrosis, obstructive lesions are more dangerous, especially if bilateral. However, bilateral renal dysgenesis (caused by diseases such as autosomal recessive polycystic kidney disease, multicystic dysplastic kidney) may be lethal.

Question 6

Renal pelvic diameter measurements can be helpful in determining the significance of hydronephrosis. What measurements would be considered significant?

Answer 6

Specific measurements are somewhat controversial. An anteroposterior (AP) diameter greater than 7 mm in the second trimester and 10 mm in the third trimester are some guidelines. Smaller is better.

Question 7

A distended bladder that does not empty suggests which diagnoses?

Answer 7

Posterior urethral valves, prune-belly syndrome, urethral atresia, or neuropathic bladder (e.g., spina bifida).

Question 8

Which is the most dangerous to the fetus?

posterior urethral valves

prune-belly syndrome

urethral atresia

neuropathic bladder

Answer 8

Urethral atresia has the highest mortality rate of these diagnoses.

Question 9

Consultation is requested for an otherwise healthy term infant with a palpable right-sided abdominal mass. Prenatal sonography was not performed. How do you proceed with your physical examination?

Answer 9

A general examination must begin with initial attention to subcutaneous nodules (neuroblastoma) or dehydration, particularly with hematuria (as seen in renal vein thrombosis). The patient should be placed in the lateral decubitus position for kidney palpation by supporting the flank with one hand and palpating the upper quadrant subcostally with the opposite hand. Care should be taken to avoid extensive abdominal manipulation after the initial examination to prevent the rare occurrence of rupture as seen in cases of Wilms tumor/mesoblastic nephroma. Transillumination of the flank mass may distinguish cystic from solid lesions. Following a complete physical examination, including careful blood pressure measurements, abdominal sonography is indicated.

Question 10

A 23-year-old pregnant female presents for evaluation of prenatally detected unilateral hydronephrosis. There is no oligohydramnios. What would be your consideration and recommendation to the patient?

Answer 10

Prenatal fetal hydronephrosis is the most commonly diagnosed fetal urologic abnormality. While the overall incidence of hydronephrosis on prenatal sonography is between 1% and 1.5%, the incidence of clinically significant hydronephrosis is between 0.2% and 0.4%. With normal amniotic fluid levels, close follow-up throughout the pregnancy and in the neonatal/newborn period as well as through the first year of life are required. It is important to note that a postnatal ultrasound evaluation performed within the first 48 hours of life may underestimate the degree of hydronephrosis due to physiologic oliguria in the newborn. The majority of cases of prenatal low-grade hydronephrosis may stabilize and resolve within the first year of life.

Question 11

A woman whose fetus was found to have unilateral hydronephrosis on prenatal ultrasound delivered a 7 lb, 3 oz otherwise healthy male infant. Postnatal sonography confirms the presence of unilateral hydronephrosis. What further evaluation do you recommend?

Answer 11

Careful physical examination with an emphasis on observing the infant’s active voiding is an important first step. The infant should be started on antibiotic prophylaxis, as the incidence of urinary tract infection (UTI) is approximately 3% to 4% in the first 6 months of life. A voiding cystourethrogram (VCUG) and nuclear renogram (DTPA or MAG3) should also be scheduled. Nuclear renography is dependent on glomerular filtration rate (GFR) for excretion of the isotope. Neonatal GFR increases several fold during the first 2 months of life. Therefore, the optimal timing of the renal scan is during the second month of life. Recent work suggests a conservative approach to nuclear renography in patients with mild hydronephrosis.

Question 12

A 32-week prenatal sonogram of a male fetus followed for hydronephrosis reveals increasing bilateral hydronephrosis, a dilated bladder, and new-onset marked oligohydramnios. What is your recommendation?

Answer 12

Posterior urethral valves leading to bilateral hydronephrosis with oligohydramnios is the most likely etiology, and this situation potentially represents a rare urologic indication for induction of labor or fetal intervention. Fetal lung maturity should be evaluated with a lecithin/sphingomyelin amniotic fluid ratio prior to a final recommendation. If fetal surgical intervention is considered, fetal renal function should be estimated by the urinary sodium chloride, osmolality, and β2 microglobulin obtained by fetal bladder aspiration. A high-grade obstruction of a single system also requires a similarly rapid response. The outcomes for fetal intervention with respect to improvement of renal function are mixed.

Question 13

A male infant delivered at an estimated 34 weeks gestational age without prenatal care demonstrates failure to thrive and neonatal ascites. The infant is noted to have a diminished, dribbling urinary stream. What is the most likely diagnosis?

Answer 13

The most common cause of bladder outlet obstruction in the male newborn is posterior urethral valves. An abdominal mass, failure to thrive, and neonatal ascites are among the most common presenting symptoms. Clearly, the widespread use of prenatal sonography has directed early investigations in patients with PUV.

Question 14

What prenatal sonographic findings are suggestive of posterior urethral valves, and what is the most important information needed to determine further prenatal care?

Answer 14

Increased bladder wall thickness on prenatal sonography may indicate outlet obstruction, and dilation of the posterior urethra (keyhole sign) is strongly suggestive of PUV. The most important information needed to determine further prenatal care is the presence and timing of onset of oligohydramnios. In the setting of oligohydramnios, increased renal echogenicity is a poor prognostic indicator. Urinary electrolytes have been shown to be a useful indicator of renal salvageability only in the setting of oligohydramnios an early gestation (18-24 weeks).

Question 15

Prenatal sonography at 22 weeks reveals bilateral hydroureteronephrosis with a distended bladder consistent with posterior urethral valves. Attempts at placement of a vesicoamniotic shunt are unsuccessful. Labor is induced at 32 weeks. What is the initial management at birth?

Answer 15

Recognition of prenatal hydronephrosis suggests the need for repeat sonography at birth to establish a baseline view of the renal collecting systems. When a suspicion of PUV exists, bladder catheterization should be performed and the patient should be placed on prophylactic antibiotics. A VCUG should be performed when the patient is stable. When posterior urethral valves are present, VCUG often demonstrates a thick, trabeculated bladder with a dilated posterior urethra.

Question 16

A 35-week gestational age male infant with apparent posterior urethral valves on VCUG has tense abdominal distention with a fluid wave and a urine output of 0.2 mL/kg/h despite aggressive fluid resuscitation. What is the most likely diagnosis?

Answer 16

Neonatal urinary ascites occurs in 7% of male infants with PUV. The diagnosis is based on clinical and radiological evidence and can be confirmed by a diagnostic tap of the ascites. When bladder outlet obstruction is suspected, catheter drainage is initiated followed by drainage of the ascites only if respiratory compromise is suspected.

Question 17

Following ablation of posterior urethral valves, difficulty passing a catheter into the bladder is encountered. What is the most likely cause?

Answer 17

Hypertrophied bladder neck resulting from bladder outlet obstruction.

Question 18

A 32-week gestational age infant is delivered after induction of labor for oligohydramnios and hydronephrosis. A cystic mass is noted on the ventral surface of the penoscrotal junction. What finding is expected on the VCUG?

Answer 18

A cystic mass at the penoscrotal junction especially with dribbling urinary stream is likely the rare finding of an anterior urethral valve. VCUG will likely show a large ventral diverticulum due to a crescentic cusp on the ventral aspect of the urethra. Vesicoureteral reflux may also be seen with this condition.

Question 19

What are causes of nonobstructive fetal hydronephrosis?

Answer 19

Vesicoureteral reflux (incidence of 15%-20% in white patients and <1% in black patients with prenatal hydronephrosis) and fetal ureteral folds are common causes of mild or transient ureteral dilatation noted on prenatal sonography.

Question 20

A prenatal sonogram detects oligohydramnios in the presence of multiple small cysts (1-2 mm in diameter). Liver sonography demonstrates periportal fibrosis. What is the most likely diagnosis, and what is its progression?

Answer 20

Hepatic fibrosis with a polycystic kidney is consistent with autosomal recessive polycystic kidney disease of the infantile form. Postnatal sonography typically reveals bilaterally large, echogenic kidneys with poor corticomedullary differentiation. (Contrast urography would reveal severely delayed function and a nephrogram with an alternating radially oriented sunray pattern.) Infantile presentation typically leads to death by 2 months of age.

Question 21

What is the most likely cause of an abdominal mass in a healthy-appearing male infant, and how can it be differentiated from the second most common cause of neonatal abdominal masses?

Answer 21

Hydronephrosis due to ureteropelvic junction obstruction is the most common cause of a neonatal abdominal mass. Multicystic dysplastic kidney (MCDK) is the second most common cause of the neonatal abdominal mass and can be distinguished from UPJ obstruction by the sonographic findings of multiple non-communicating cysts, minimal or absent renal parenchyma, and the absence of a central large cyst. The two entities can also be differentiated by the 99^mTc DMSA renal scan. The renal scan usually demonstrates some function in the hydornephrotic kidney and nonfunctioning of the MCDK.

Question 22

An infant is diagnosed with a right MCDK. What is of concern regarding the contralateral kidney?

Answer 22

The contralateral kidney and collecting system must be carefully studied in cases of MCDK. Contralateral vesicoureteral reflux is the most commonly encountered abnormality with an incidence of 15% to 40%. Contralateral hydronephrosis due to UPJ obstruction occurs in approximately 10% of infants with MCDK.

Question 23

A 1-month-old female infant is admitted to the neonatal intensive care unit (NICU) with failure to thrive and respiratory distress. Physical examination reveals a large right-sided abdominal mass. Sonography reveals an enlarged right kidney with multiple non-communicating cystic structures. A renal scan reveals no perfusion to the affected side and normal function of the left kidney. What treatment would you recommend?

Answer 23

This clinical scenario is consistent with the findings of MCDK. Symptoms including respiratory distress, failure to thrive, hypertension, or hemorrhage are indications for nephrectomy in certain cases of MCDK. However, a subset of these patients may be managed by aspiration of the dominant cyst(s), as the cystic fluid does not tend to re-accumulate. Aspiration can typically be done by sonographic guidance and may provide immediate or even long-term management.

Question 24

A clinically stable, otherwise healthy term neonate is diagnosed with left MCDK by sonography. The right kidney is noted to be free of reflux with intact renal function. Is there a role for observation?

Answer 24

In the absence of hypertension, feeding, or developmental problems due to mechanical or obstructive complications, immediate surgical excision is unnecessary. Concern for onset of hypertension, malignant degeneration of the MCDK to Wilms’ tumor, or, less commonly, renal cell carcinoma remains an argument for prophylactic removal of these nonfunctioning moieties. The minimal morbidity of a procedure accomplished through a small incision and the freedom from regular follow-up or sonography are additional factors favoring nephrectomy. Non-interventional follow-up and the ability to sonographically follow MCDK, as well as the high incidence of near-complete involution favor observation in these cases. One must remember, however, that while the cystic fluid found within MCDK may be resorbed, the cyst wall is a persistent remnant. MCDK should be followed sonographically until at least age 5; nephrectomy should be performed if there is an increasing solid component.

Question 25

A term infant is noted to have a fixed, unilateral mass extending to the midline. Also noted are multiple bluish skin nodules. What is the most likely diagnosis and treatment?

Answer 25

This clinical picture most likely represents neuroblastoma, an embryonal tumor of neural crest origin. Neuroblastoma is the most common solid abdominal mass and the most common malignant tumor in infancy. For low-stage tumors (stage I to II), surgical excision remains the treatment of choice. For stage III and higher disease, chemotherapy and radiation therapy are employed as multimodal therapies. As an exception for higher stage disease, surgical excision is often the standard of care without irradiation or chemotherapy in cases of stage IV-S disease (hepatic metastases, skin nodules, and bone marrow involvement).

Question 26

A term female infant is oliguric at 48 hours of age. Physical examination reveals a palpable, distended bladder and an erythematous interlabial mass. Renal sonography reveals hydronephrosis of the left upper pole. What is the most likely diagnosis?

Answer 26

The most common cause of urethral obstruction in the female infant is an obstructing ureterocele. In addition, 80% of ureteroceles are associated with the upper pole ureter of a minimally functioning duplicated system. The sonographic findings are consistent with a ureterocele arising from a duplicated collecting system.

Question 27

Antenatal sonography of a 25-week gestational age female fetus reveals right-sided hydronephrosis and an intravesical cystic dilatation consistent with a ureterocele. Follow-up postnatal sonography, however, demonstrates persistent hydronephrosis, but no obvious ureterocele. What technical errors during sonography may confound the diagnosis?

Answer 27

There are common errors in the sonographic technique that may render the diagnosis of ureteroceles difficult. If the bladder is overdistended, then the ureterocele may become effaced and may not be visible on sonography and even on VCUG. Additionally, if the injected contrast is too concentrated on cystourethrography, the ureterocele may become obscured on radiologic imaging. On the other hand, if the bladder is completely empty during sonography, a large ureterocele can mimic the wall of the bladder, and distinction between the bladder wall and ureterocele may be difficult.

Question 28

A neonate is noted to have deficiency of abdominal wall musculature, diffuse dilatation of the urinary tract, and hydronephrosis. The patient is clinically stable. Does this patient require acute urological intervention to address the upper tract dilatation?

Answer 28

Rarely does a case of group 2 prune-belly syndrome as described above require urgent urological intervention. Sonography and serial electrolytes are used to assess parenchymal reserve and extent of uropathy. A diuretic renal scan should be performed. Patients presenting with group 1 characteristics, on the other hand, including oligohydramnios, pulmonary hypoplasia, cardiac anomalies, urachal abnormalities, or pneumothorax require intervention for the cardiopulmonary abnormalities prior to other aspects of care.

Question 29

A neonate with prune-belly syndrome (group 2) may be expected to have up to an 85% rate of vesicoureteral reflux. Should a VCUG be immediately performed to determine the grade of reflux and subsequent treatment?

Answer 29

Instrumentation of a neonate with prune-belly syndrome is associated with a high risk of infection and should be performed only with antibiotic prophylaxis.

Question 30

A lower abdominal mass is palpated in a newborn female. Examination of the perineum reveals a mass in the introitus. The mass persists following the placement of a urethral catheter. What is the most likely diagnosis?

Answer 30

A lower abdominal mass in an otherwise healthy female patient is most likely due to hydrometrocolpos or distension of the vagina and uterus.

Question 31

What anatomical abnormalities most commonly lead to hydrometrocolpos?

Answer 31

An imperforate hymen is the most common cause of hydrometrocolpos. A less common etiology is a high transverse vaginal septum, which can be associated with a persistent urogenital sinus. In cases of a high transverse vaginal septum, the external anatomy may appear deceptively normal but sonography of the abdominal mass will reveal a cystic midline structure posterior to the bladder without septation.

Question 32

On prenatal sonography, the bladder cannot be identified. What condition should be considered?

Answer 32

Inability to identify the bladder on repeat studies should raise suspicion for bladder exstrophy. Common observations in the fetus with bladder exstrophy include nonvisualization of the fetal bladder, a lower abdominal wall mass inferior to a low-lying umbilicus, diminutive genitalia, and abnormal widening of the iliac crests.

Question 33

A term male infant is noted to have multiple genitourinary anomalies at birth consistent with the classic bladder exstrophy/epispadias complex. How must the exstrophic bladder be maintained prior to surgical intervention?

Answer 33

The mucosa of the bladder must be protected while the candidacy for surgery is discussed. Noncontact care may consist of placing the child in an incubator without a diaper and with saline mist to keep the mucosa moist. Alternatively, the bladder mucosa may be protected by a plastic wrap to prevent the mucosa from sticking to clothing or to the diaper. The umbilicus should be ligated with silk suture rather than a plastic umbilical clamp when exstrophy is recognized antenatally or postnatally. Broad-spectrum antibiotics may be started to sterilize the bladder wall prior to surgical intervention.

Question 34

A term male infant is brought to the emergency department with fever, irritability, and weight loss. The infant is uncircumcised. Until what age is the infant more susceptible to UTI than circumcised male infants?

Answer 34

Regardless of phimosis, the presence of a foreskin predisposes an infant to UTI until approximately 6 months of age versus age-matched circumcised males. Colonization of the newborn prepuce diminishes as a risk factor beyond 6 months of age.

Question 35

Three days following Gomco clamp circumcision, a newborn infant develops brisk bleeding from the incision. What is the risk of hemorrhage, and how should it be treated following circumcision?

Answer 35

Hemorrhage occurs in <1% of cases. The incidence is highest at 3 days after birth due to the physiologic depression of plasma levels of vitamin K-dependent clotting factor. If conservative measures such as compression with an epinephrine-soaked gauze sponge or thrombin application fail, hemostatic suture placement is required.

Question 36

Consultation is requested approximately 7 days following a neonatal circumcision. Examination of the penis reveals dehiscence of the incision line with complete exposure of the ventral penile shaft. What is the preferred approach?

Answer 36

Healing by secondary intention is the preferred approach following such a dehiscence. In rare cases, extensive denudation of skin may require skin grafting to prevent secondary chordee or scarring. Other acute complications of neonatal circumcision include infection, laceration, glans amputation, urinary retention, and necrosis. Nonacute complications of neonatal circumcision include excessive residual skin, skin asymmetry, epithelialized skin bridges, epidermal inclusion cysts, skin tethering/chordee, concealed (buried) penis, phimosis, meatal stenosis, urethrocutaneous fistula, and lymphedema.

Question 37

Consultation is requested for a glans amputation during a neonatal circumcision. How should this be managed?

Answer 37

As with all acute complications during circumcision, immediate attention and treatment is the best management. Generally, glans amputation is partial. The amputated portion should be wrapped sterilely and kept cool on ice. It should not be submerged in saline. Primary anastomosis with long-lasting absorbable sutures (e.g., PDS) should be performed. There are no vessels of sufficient size to permit microvascular re-anastomosis. The urethra should be stented. Viability of the amputated portion is improved when repair occurs within hours of the injury, but it has even been documented in delays up to 18 hours.

Question 38

A newborn undergoes a circumcision with a Gomco clamp. Three days later, he has two separate streams. What is the next step?

Answer 38

Urethrocutaneous fistula is a rare complication of circumcision. It may occur if the urethra is crushed by the circumcision clamp or if a suture is inadvertently placed into the urethra. This can be repaired if recognized immediately. When the diagnosis is delayed, observation for 4 to 6 months may result in spontaneous closure. Otherwise, formal closure of the fistula will be needed.

Question 39

During newborn infant circumcision, local anesthetic containing 1:1000 epinephrine is injected. Blanching of the penile skin and glans is observed. Physical exam demonstrates mild peripheral vasoconstriction of the hands and feet, blood pressure of 90/60 mm Hg, and a pulse of 160. What is the next step?

Answer 39

This patient has primarily local effects of the injected epinephrine. These can be treated with the alpha-adrenergic antagonist phentolamine delivered subcutaneously at the injection site at a dose of 0.1 to 0.2 mg/kg. The patient should be monitored closely for adverse effects.

Question 40

A 9-day-old infant undergoing a sepsis workup is noted to have a palpable right-sided abdominal mass with associated gross hematuria. What is the most likely diagnosis?

Answer 40

The most likely diagnosis is renal vein thrombosis (RVT). Sixty to seventy percent of patients with RVT have findings of a palpable mass with associated gross hematuria and proteinuria.

Question 41

A 2-day-old infant born to a diabetic mother has polyuria (10 mL/kg/h). Is the child at risk for compromised renal function?

Answer 41

Yes. Infants of diabetic mothers experiencing an osmotic diuresis as well as infants with profuse diarrhea, sepsis, acute hypoxia, and hypotension are at risk for RVT. RVT often occurs due to low perfusion pressures and increased blood viscosity secondary to extracellular volume contraction with resultant sludging of blood in renal venules.

Question 42

A 4-day-old infant with a palpable abdominal mass, gross hematuria, and thrombocytopenia undergoes an abdominal Doppler sonogram that confirms the diagnosis of unilateral RVT without caval thrombus. What does appropriate treatment include?

Answer 42

Vigorous hydration, electrolyte management, and treatment of the underlying cause are critical. Aggressive anticoagulation and thrombolytic therapy are employed in certain situations. Thrombolytic agents such as urokinase, streptokinase, and tissue plasminogen activator are utilized for bilateral RVT.

Question 43

Following successful treatment of RVT, what sequelae may develop?

Answer 43

Fibrosis of the kidney, renovascular hypertension, nephrotic syndrome, and chronic pyelonephritis are all possible sequelae of RVT. Hypertension in association with an atrophic kidney is often renin-mediated, and a nephrectomy is curative.

Question 44

A 35-week gestation newborn is anuric for 36 hours following birth. Physical examination is unremarkable. Should a workup for acute renal failure commence?

Answer 44

No. 92% and 99.4% of term newborns void within 24 hours and 48 hours of birth, respectively. Acute renal failure is suspected only if anuria persists more than 48 hours.

Question 45

A 35-week gestation newborn did not void for 36 hours following birth. His urine output is 0.7 mL/kg/h and his serum creatinine is 1.1 mg/dL at 72 hours. There is no history of oligohydramnios. What is the most common cause of oliguria in the newborn, and how is it treated?

Answer 45

Prerenal renal failure secondary to inadequate perfusion is most common cause of oliguria in the newborn. Hypotension from sepsis, maternal antepartum hemorrhage, or surgical bleeding may lead to renal hypoperfusion. Similarly, congestive heart failure due to cardiac anomalies or dehydration may also lead to renal ischemia. Neonatal intensive care admission with volume expansion will rapidly reverse prerenal renal failure. Oligohydramnios is usually present in infants with anuria or oliguria due to postrenal causes.

Question 46

A term infant in the neonatal intensive care unit has multiple unsuccessful attempts at umbilical artery catheterization. Consultation is requested 24 hours later for apparent new-onset neonatal ascites. What is the likely diagnosis and recommended treatment?

Answer 46

Urachal laceration due to attempted umbilical arterial catheterization is the most common cause of neonatal intraperitoneal bladder rupture. Evaluation should consist of a VCUG and possibly a diagnostic paracentesis. While management may be conservative for most cases of neonatal ascites, initial operative management is recommended in cases of intraperitoneal bladder rupture.

Question 47

A 1300-gm preterm infant is being treated for respiratory distress syndrome (RDS) in the NICU. Abdominal x-rays reveal bilateral 0.7 mm renal stones. What is the etiology of this condition?

Answer 47

Furosemide, commonly used in the treatment of RDS and other conditions common to premature infants in the NICU setting, is associated with nephrolithiasis. Furosemide causes a hypercalciuric state with a secondary increased resorption of calcium in the proximal tubule and subsequent renal stone formation. Excessive calcium and glucose intake in specialized formulas for premature infants is an other recognized cause of neonatal nephrolithiasis.

Question 48

A premature infant in the NICU with a patent ductus arteriosus receives furosemide at 2 mg/kg/d for 4 weeks. An abdominal x-ray reveals bilateral nephrocalcinosis. What is the most appropriate treatment?

Answer 48

Furosemide-induced renal parenchymal stone disease rarely requires surgical intervention. The administration of hydrochlorothiazide, reduced calcium intake, and cessation of furosemide therapy often results in resolution of nephrolithiasis. Nephrocalcinosis may be followed with serial sonography. A baseline calcium-to-creatinine ratio of less than 0.2 portends a higher rate of resolution. In cases of discrete massive calculus formation, shock wave lithotripsy or open surgical intervention may be warranted.

Question 49

Umbilical artery catheterization is performed on a premature infant in the NICU. 24 hours later, the infant has gross hematuria and hypertension. The hypertension is refractory to aggressive medical management. What is the diagnosis and the most appropriate treatment?

Answer 49

A recognized complication of umbilical artery catheterization is renal artery thrombosis, either alone or as part of an extensive aortoiliac thrombus. The clinical diagnosis can be confirmed by Doppler sonography and radionuclide imaging, if necessary. Management is dependent on the clinical setting, and unilateral involvement is best managed expectantly, although thrombolytic therapy may be appropriate. Control of hypertension is the most important aspect of management and occasionally requires nephrectomy, as in this life-threatening case.

Question 50

A 38-week gestational age male infant is delivered following prolonged labor with meconium aspiration. Aggressive resuscitation efforts are successful. On day 3 of life, an abdominal mass is palpated on the right side. What is the likely sonographic finding, and what is your diagnosis?

Answer 50

Sudden increases in intra-abdominal pressure during prolonged labor may result in adrenal hemorrhage with the observed physical findings. Adrenal hemorrhage typically involves the right adrenal gland, and sonographic findings initially demonstrate a hyperechoic or solid mass over the superior pole of the kidney. With time, the lesion may become hypoechoic and decrease in size. This finding should not be confused with neuroblastoma, the most common adrenal malignancy of infancy, which typically has a solid appearance on sonography but may be cystic or have a mixed echogenic pattern.

Question 51

A 39-week old term infant has a firm right scrotal mass at birth. The mass is painless and does not transilluminate. The overlying skin is erythematous and indurated. What is the most likely cause, and what other entities should be considered in the differential diagnosis?

Answer 51

The most common cause of a scrotal mass at birth is testicular torsion. The differential diagnosis for the described presentation includes hydrocele, incarcerated inguinal hernia, scrotal hematoma, tumor, meconium, trauma, and more rarely ectopic spleen or adrenal tissue.

Neonatal testicular torsion is extravaginal, since the tunica vaginalis is not adherent to the surrounding dartos fascia of the scrotal wall until 4 to 8 weeks of age. Torsion in the neonate, therefore, involves the testis, spermatic cord, and overlying tunica vaginalis. In the adolescent, the tunica vaginalis is fixed to the dartos fascia; therefore, testicular torsion is intravaginal.

Question 52

An infant with a firm scrotal mass at birth is diagnosed with testicular torsion. The infant is hemodynamically stable, and the contralateral testis is normal. Is surgical exploration and detorsion with orchidopexy necessary?

Answer 52

It is well known that successful testicular salvage in the event of neonatal testicular torsion is exceedingly rare. Exploration with an intent of salvage alone is not justified. The role of scrotal exploration with contralateral testicular fixation due to the potential for asynchronous torsion until the tunica vaginalis adheres to the scrotal wall remains controversial. Clearly, however, if bilateral torsion is suspected, then exploration despite the low incidence of salvage is necessary.

Question 53

A term male infant is admitted to the intensive care unit immediately postpartum with hypotension and tachycardia. Physical examination is remarkable for a penis of only 1.5 cm stretched penile length. The external genitalia are otherwise normal. Electrolyte studies reveal hyponatremia, hyperkalemia, and hypoglycemia. What is the most likely diagnosis, and how must the infant be treated?

Answer 53

This critically ill infant with obvious micropenis (penile length 2.5 standard deviations below the mean or <2.0 cm in a newborn male) must be evaluated for panhypopituitarism. Following intravenous glucose and electrolyte replacement, serial serum glucose, sodium, and potassium evaluations are necessary. Serum gonadotropin and testosterone measurements from birth through 3 months of age will eventually document a neonatal luteinizing hormone (LH) surge in normal infants.

Question 54

On initial examination, a term infant has left-sided cryptorchidism and a midshaft hypospadias. What is the incidence of a disorder of sexual development (DSD) in this patient?

Answer 54

Phenotypic males with cryptorchidism and hypospadias are estimated to have a 20% to 30% incidence of DSD. Similarly, male phenotype with bilateral nonpalpable testes and perineal hypospadias alone should initiate an investigation for DSD.

Question 55

What familial risk factors increase risk of DSD in infants?

Answer 55

Most DSD result from autosomal recessive inheritance, and inquiry regarding siblings with abnormal genitalia, infant death, or abnormal events at puberty is necessary. Maternal ingestion of androgenic meditation (e.g., danazol), pro-gestational agents, or drug abuse should also be carefully investigated.

Question 56

A term infant with severe hypospadias and unilateral cryptorchidism is suspected of having DSD. What is the most common DSD with this presentation?

Answer 56

The most common DSD in patients with severe hypospadias, a testis on one side, and a nonpalpable undescended testis is mixed gonadal dysgenesis. This patient likely has a testis on one side and streak gonad on the contralateral side.

Question 57

Physical examination of a 37-week-old infant shows a hypertrophied clitoris and partially fused, rugated labioscrotal folds. The karyotype is 46 XX. What is the diagnosis and the most likely cause?

Answer 57

The infant likely has a 46 XX DSD, previously referred to as a “female pseudohermaphrodite.” This group constitutes 60% to 70% of all DSD in the neonatal period. Congenital adrenal hyperplasia (CAH) is the most likely cause in patients with a 46 XX DSD.

Question 58

An infant is suspected of having CAH. What life-threatening condition must be considered, and how is it diagnosed?

Answer 58

A potentially lethal metabolic consequence associated with DSD is the salt-wasting form of CAH, which does not typically manifest in electrolyte disturbances until 1 to 2 weeks postnatally. Therefore, the etiology of DSD must be determined prior to discharge. CAH results from 21-hydroxylase deficiency in 95% of cases. The more common form leads to virilization and aldosterone deficiency in three-fourths of patients, while virilization alone is present in approximately one-fourth of patients with a 21-hydroxylase deficiency. Salt wasting may also be present in patients with the much rarer causes of CAH, including 11ß-hydroxysteroid dehydrogenase deficiency (<1% of patients with CAH, almost always manifests with salt wasting).