Sonographic differential diagnosis of duplex kidneys.

Duplex kidneys have two renal pelvises and two ureters, which can join on the way to the urinary bladder but can also enter the bladder separately. A distinction must be made between normal and pathological duplex kidneys. In normal duplex kidneys, both renal pelvises are normal in width, and the upper and lower poles are approximately the same size. Furthermore, ureters are not dilated, and the upper and lower poles of the kidneys are not cystically altered. In contrast, pathological duplex kidneys, occurring in about 50 % of cases, are characterized by dilation of one or both renal pelvises. Additionally, one or both ureters may be dilated. Megaureters may be obstructive or refluxive. If a megaureter is present, a ureterocele must be ruled out, as well as an ectopically opening ureter. A pathological duplex kidney must always be assumed if one pole of the kidney is hypoplastic. Hypoplasia of the upper renal pole is often associated with an obstructive megaureter. Vesicoureteral reflux into the lower pyelon is common in hypoplasia of the lower pole. In the presence of vesicoureteral reflux, the associated (lower) pyelon is dilated when the bladder is full or during micturition. In addition, there is a dilated ureter. On the other hand, the pyelon can have a normal width when the bladder is empty. In rare cases, one pole may be cystically altered in pathological duplex kidneys. In this instance, segmental multicystic dysplastic duplex kidney must be differentiated from segmental multicystic nephroma.

Differential Diagnosis of Acute Scrotum in Childhood and Adolescence with High-Resolution Duplex Sonography.

Acute testicular pain in childhood can be caused by testicular torsion, torsion of the appendix testis, or epididymo-orchitis. Quick and reliable diagnosis is essential for determining the further course of action (surgery or conservative approach). The diagnostic tool of choice is high-resolution sonography with a linear transducer (> 10 MHz) combined with color and spectral Doppler sonography. The Doppler device settings should include a low pulse repetition frequency (< 4 cm/s), a low wall filter (< 100 Hz), and adequate gain. Comparison with the unaffected healthy testis is essential. The most important of the three diseases is torsion of the spermatic cord because it requires immediate surgical intervention and detorsion. The affected testis is enlarged and has an inhomogeneous echotexture with hypoechoic and hyperechoic areas as well as an associated hydrocele. In testicular torsion, color Doppler shows reduced or absent intratesticular vessels in comparison with the healthy contralateral testis. Spectral Doppler shows decreased flow velocities especially during diastole in intratesticular arteries and an increased resistance index. The investigation should always include imaging of the spermatic cord from the outer inguinal ring to the upper pole of the testis. In contrast to a normal finding, the vessels and the ductus deferens are not displayed as linear tubular structures but in form of a spiral twist. Ultrasound shows a target-like structure with multiple concentric rings. Color Doppler sonography shows the typical whirlpool sign. In torsion of the appendix testis, the appendix testis is enlarged in the groove between the testis and epididymis. The longitudinal diameter of the appendix testis can be greater than 5 mm. The echogenicity of the torsed appendage can vary between hypoechoic (acute torsion) and hyperechoic (prior torsion). An associated hydrocele of varying size is usually seen. Color Doppler sonography reveals a lack of perfusion of the enlarged appendix testis and increased vascularity of the testis and primarily the epididymis. Epididymo-orchitis is characterized by an enlarged epididymis and/or testis with inhomogeneous echogenicity (hypoechoic - hyperechoic). Color Doppler sonography shows increased vascularity in comparison with the unaffected testis. Spectral Doppler reveals increased diastolic flow velocities and a decreased resistance index. Idiopathic scrotal edema and an incarcerated inguinal hernia must be ruled out in the differential diagnosis.

Sonographic and Doppler Sonographic Diagnosis of Necrotizing Enterocolitis in Preterm Infants and Newborns.

Necrotizing enterocolitis (NEC) occurs primarily in immature preterm infants with low birth weight. It has a prevalence of 7 - 11 % with a poor prognosis and a mortality rate of 20 - 40 %. Plain abdominal radiography is still considered the diagnostic method of first choice even though ultrasound can visualize significantly more findings suspicious for NEC. Such as thickened bowel walls, dilated fluid-filled bowel loops, and gas bubbles in the intestinal wall, portal vein. Moreover, it is possible to assess intestinal peristalsis, to differentiate between intraluminal and extraluminal fluid and to assess the location of fluid accumulations and their internal echo pattern. In addition, free intraabdominal gas can be visualized on ultrasound. Increased flow rates in the mesenteric arteries and decreased flow in the portal vein can be detected on Doppler ultrasound in NEC. Color-coded Doppler ultrasound can be used to differentiate between bowel loops with increased and decreased perfusion and thus at risk for perforation. Ultrasound is therefore superior to conventional radiography in many regards and should replace it as the diagnostic method of first choice not least because of its noninvasive nature.

Sonographic Diagnosis of Meningoencephalitis in Newborns and Infants.

Prenatal, neonatal meningoencephalitis and infections of the brain in older infants are often associated with serious complications which can be diagnosed by sonography through the open fontanelles. Most frequently postmeningitic hydrocephalus and subdural effusions occur. Rarer complications are brain abscesses and ventriculitis which are caused by gram negative bacteria such as E. coli, Serratia marcescens, Proteus and Enterobacter. A serious complication after ventriculitis is the development of compartment hydrocephalus. Multifocal small echogenic lesions scattered all over the brain are suspicious of fungal infections. Stripe-like echogenicities in the basal ganglia of newborns are typical for prenatal infections such as infections with cytomegalovirus, rubella, herpes, toxoplasma gondii and HIV. Late sequelae are intracranial cysts, multifocal encephalomalacia and intracranial calcifications. Color Doppler shows increased perfusion of the brain in the acute phase of the disease. Brain abscesses and infarcts are characterized by decreased or missing perfusion. Spectral Doppler shows increased flow velocities. Increased intracranial pressure causes an increase of the flow velocities in the intracranial part of the internal carotid artery in comparison with the extracranial part. All complications can be diagnosed by ultrasound. Other imaging methods such as MRI are only occasionally necessary.

Duplex Sonographic Diagnosis of Perinatal Hemorrhagic Stroke.

Children are particularly at risk for stroke in the neonatal period. Neonatal hemorrhagic stroke is rarer than ischemic stroke. The incidence is 40.7/100 000 live births. Hemorrhagic stroke is caused by a disruption in venous drainage usually due to local thrombosis. As a result of the nonspecific clinical symptoms in this age group, diagnosis is usually made too late. The only relatively specific symptom is a cerebral seizure during the first week of life. Therefore, stroke should be ruled out by diagnostic imaging in the case of any seizure in the first days of life. The diagnostic method of choice is MRI, but it is not always available. Most neonatal strokes can be detected with high-resolution duplex ultrasound. Hemorrhagic stroke appears as a focal increase in echogenicity in a venous drainage area on ultrasound. The corresponding venous drainage can be visualized with duplex ultrasound and measured with spectral Doppler. Hemorrhagic stroke of the internal veins appears as hemorrhage in the basal ganglia. Venous thrombosis must be ruled out in every cerebral hemorrhage of unclear origin in an otherwise healthy term newborn. In the case of hemorrhagic infarction of the basal ganglia, both internal cerebral veins, the great vein of Galen, and the straight sinus must be examined with Doppler ultrasound. Doppler ultrasound should be used to differentiate between complete occlusion and severe stenosis. The recanalization of vessels and the morphological consequences of hemorrhagic stroke can be visualized in the further course.

Sonographic and Doppler Sonographic Diagnosis of Neonatal Ischemic Stroke.

Children are particularly at risk for stroke in the neonatal period. 1/3 of all strokes in children occur during the perinatal period. The incidence of perinatal stroke is 1:4000. A differentiation is made between ischemic stroke and hemorrhagic stroke. Ischemic strokes are caused by arterial occlusion due to thrombosis or embolism. As a result of the nonspecific clinical symptoms in this age group, diagnosis is usually made too late. The only relatively specific symptom is focal cerebral seizure during the first week of life. Therefore, stroke should be ruled out by diagnostic imaging in the case of any seizure in the first days of life. Although the diagnostic method of choice is MRI, it is not always available. Most neonatal ischemic strokes can be detected with high-resolution duplex ultrasound. On ultrasound, ischemic stroke appears as a wedge-shaped focal increase in echogenicity in the supply region of an artery, typically the middle cerebral artery. The corresponding arterial inflow can be visualized with duplex ultrasound and measured with spectral Doppler. Doppler ultrasound can be used to differentiate between complete occlusion and severe stenosis. The success of therapeutic measures can be determined in the further course with Doppler ultrasound on the basis of the recanalization of vessels and the morphological consequences of stroke (cyst formation due to liquefactive necrosis).

Postnatal respiratory distress in a dichorial twin with congenital thoracic neuroblastoma after assisted reproduction by intracytoplasmatic sperm injection.

We report on the case of a female twin with congenital thoracic neuroblastoma after conception via intracytoplasmatic sperm injection (ICSI). Birth occurred at 37 + 1-week gestation per primary sectio caesarea. Acute respiratory distress necessitated intubation and mechanical ventilation. Ultrasound and magnetic resonance imaging (MRI) showed a mass in the right upper thorax compressing the trachea. The tumor was subtotally excised and histological analysis revealed neuroblastoma. No further treatment was given. The residual primary tumor regressed spontaneously. Four years after diagnosis, both twins are healthy and normally developed.