Diagnostic ultrasound ( PDFDrive )

CHAPTER 52 The Pediatric Urinary Tract and Adrenal Glands 1791
appropriate choice of transplant is dictated by the presence or
absence of coexistent TPN-related chronic liver disease or chronic
kidney failure resulting from urologic disease. 56 hese options
include isolated intestinal transplantation, combined liverintestinal
transplantation, and multivisceral transplantation.
Bladder Exstrophy
Bladder exstrophy is a rare congenital malformation characterized
by an infraumbilical abdominal wall defect, incomplete bladder
closure with mucosal continuity with the anterior abdominal
wall, epispadias, and associated abnormalities of the pelvic bones
and musculature. his disorder is a component of the exstrophyepispadias
complex, with epispadias at the mild end of the
spectrum and cloacal exstrophy at the severe end. Bladder
exstrophy is the most common of these abnormalities and occurs
most oten in boys. 57 Clinical features include bladder eversion,
epispadias, wide diastasis of the pubic bones, and anterior displacement
of the anus as a result of muscular deiciency. In boys, the
penis will be shortened with wide separation of the corporal
attachments and dorsal curvature. In girls, there is a biid clitoris.
he ureters have a low bladder insertion with a characteristic
J-shaped course due to an enlarged pouch of Douglas that
displaces the ureters inferolaterally. Unless ureteral reimplantations
are performed, these patients will all develop VUR ater exstrophy
closure. 57
Modern staged repair of bladder exstrophy is a two-step
process in girls and a three-step process in boys. In stage I, the
bladder and abdominal wall defects are closed in both sexes 48
to 72 hours ater birth, with epispadias repair only in girls. If
the pubic diastasis is greater than 4 cm or the malleability of
the pelvis is poor, iliac osteotomies may be performed at this
time. In stage II, the male urethra is closed, usually between 6
and 12 months of age. In stage III, bladder neck reconstruction
and bilateral ureteral reimplantation are performed, generally
at 4 to 5 years of age, when the child can take part in a voiding
program. 58
Ater repair, the bladder will appear small on ultrasound
imaging with irregular contours and a thickened wall. he kidneys
generally have a normal appearance, although hydronephrosis
may occur as a result of VUR, bladder outlet obstruction, or
urethral stricture. Renal scarring can develop from recurrent
pyelonephritis or obstructive uropathy ater bladder neck
reconstruction.
Bladder augmentation using a segment of bowel is an option
for children who cannot undergo bladder neck reconstruction
because of a low bladder capacity, abnormal bladder compliance,
or incontinence. 59 Ileocystoplasty is the most popular choice,
although other bowel segments can be used. By ultrasound,
the augmented bladder segment will be identiied superior
to the native bladder, and will demonstrate an undulating contour.
he characteristic “gut signature” of the augmented segment is
readily identiied 59 (Fig. 52.22). Echogenic intraluminal mucus
or debris is oten noted.
Urachal Anomalies
he fetal urachus is a tubular structure extending from the
umbilicus to the bladder. It normally closes by birth, and a urachal
FIG. 52.22 Sigmoid Cystoplasty in Patient With History of Bladder
Exstrophy. Longitudinal image demonstrates bladder (B) with augmented
segment located superiorly (*). Note the undulating contour of the
augmented segment with the outer hypoechoic muscular layer (arrow)
and the inner hyperechoic layer of bowel mucosa (arrowhead).
remnant may be visible as a hypoechoic, elliptical mass on the
anterosuperior aspect of the bladder (Fig. 52.23). A patent urachus
is present if there is a complete tubular connection from the
bladder to the skin surface at the umbilicus (about 50%), or only
a portion may be open as a blind-ending urachal sinus arising
either from the bladder dome (vesicourachal diverticulum,
about 3%-5%, Fig. 52.24) or from the umbilicus (umbilicourachal
sinus, about 15%). When only the midportion of the urachus
remains patient, a urachal cyst is the result (about 30%) 60
(Fig. 52.25).
he literature is inconclusive on how to manage pediatric
urachal lesions, especially those discovered incidentally. Both
the therapeutic and the prophylactic value of surgical resection
are ill deined. A recent retrospective review of 721 patients by
Gleason and colleagues concluded that urachal anomalies are
more common than previously reported, and that children with
asymptomatic lesions do not appear to beneit from prophylactic
excision, as the risk of malignancy later in life is remote. 61
URINARY TRACT INFECTION
UTI is a common clinical problem in children and a frequent
indication for renal sonography. he imaging workup of the
child with a UTI is usually performed ater the irst culture has
documented infection in an infant or child. he purpose of the
workup is to identify congenital anomalies, obstruction, and
other abnormalities that may predispose the patient to infection.
Sonography of the urinary tract, including the kidneys and
bladder, is used for initial screening. VCUG is indicated ater a
irst UTI only if ultrasound reveals hydronephrosis, scarring, or
other abnormalities suggestive of high-grade VUR or obstructive
uropathy or in patients with complex clinical conditions. VCUG
is also recommended if there is a recurrence of a febrile UTI. 62
In most centers in the United States, conventional luoroscopic
VCUG is performed for evaluation of the bladder and urethra