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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5514_Библиотеки_им_академика_М_И_Перельмана.pdf
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E. R. Oliver and S. J. Back
a
b
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Fig. 4.8 MRI ndings of classic bladder exstrophy at 21weeks gestation with a large infraumbilical defect mimicking an omphalocele. (a) Transverse SSFP image (TR/TE ms, 4.05/1.65) through
the lower abdomen just below the level of the umbilical cord insertion demonstrates the absence of
a uid-lled bladder and a large infraumbilical defect (arrowheads) containing bowel loops. (b)
Sagittal FSE T2-weighted image (TR/TE ms, 1100/76) through the mid-abdomen demonstrates a
large ventral wall defect (arrowheads) that was immediately below the level of the ACI (not shown)
representing the exstrophied bladder with protruding bowel contained by the bladder plate. (c)
Sagittal T1-weighted gradient echo image (TR/TE ms, 202/4.76) through the lower abdomen and
pelvis demonstrates a normal course of the T1-hyperintense meconium (arrows) extending to the
perineum, which argues against imperforate anus/anorectal malformation. Meconium-lled loops
of the bowel are also noted within the large infraumbilical defect. No other ndings on US or MRI
were present to suggest cloacal exstrophy, and postnatal examination conrmed the presence of
classic bladder exstrophy with a large infraumbilical defect mimicking an omphalocele
4 Prenatal and Postnatal Imaging of the Bladder Epispadias-Exstrophy Complex
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The characteristic prenatal imaging ndings of cloacal exstrophy include those
of bladder exstrophy, an omphalocele, an inability to identify a normal anal orice,
and a spinal abnormality (Fig.4.9). In cloacal exstrophy, the primary prenatal ultrasound ndings of bladder exstrophy are similar to isolated bladder exstrophy—an
infraumbilical ventral wall defect, “absent” bladder, low abdominal cord insertion,
and pelvic anomalies. However, it is important to recognize that the exstrophied
bladder in cloacal exstrophy consists of two hemibladders that are separated by the
cecal plate. Moreover, prolapsed ileum may extend from the cecal plate between the
hemibladders and result in the characteristic “elephant trunk sign” (Fig.4.10) [17].
Detection of an omphalocele can be challenging in the setting of the infraumbilical
defect associated with bladder exstrophy, and especially if the omphalocele is small.
Nevertheless, careful attention should be directed at the abdominal wall, and an
omphalocele should be suspected if the ventral wall defect is observed to involve
and/or extend above the level of the abdominal cord insertion (Fig.4.9). An inability
to document a normal anal dimple and/or the presence of a dilated rectum should
raise strong suspicion for imperforate anus (Fig.4.8) or anorectal malformation.
Lastly, any spinal abnormality may be present. A closed spinal dysraphism (i.e.,
myelocystocele and lipomyelomeningocele) is considered a strict criterion for the
classic diagnosis of cloacal exstrophy; however, the severity of spinal abnormalities
may be mild and take the form of vertebral segmentation anomalies or a low conus
medullaris (Figs.4.10 and 4.11) [18].
Experienced sonologists are often capable of identifying the myriad abnormalities present in cloacal exstrophy; however, fetal MRI is a useful adjunct for clarifying or conrming the ndings of cloacal exstrophy, especially in the setting of
unfavorable fetal lie, anterior placenta, and/or maternal factors. Similar to ultrasound, a uid-lled bladder will not be identied on T2-weighted MR images, and
prolapse of the distal ileum between the exstrophied hemibladders may also be present. The ability of MRI to obtain a sagittal image of the abdominal wall regardless
of fetal lie and maternal factors is helpful in assessing the relationship of the ventral
wall defect to the abdominal cord insertion and whether a small omphalocele is
present (Fig.4.11). T1-weighted sequences nicely depict the course of meconium in
the distal colon, and an inability to trace the meconium signal to the level of the
perineum or an abnormal course of the meconium signal in the distal-most colon
should raise concern for imperforate anus or other anorectal malformation
(Figs.4.11 and 4.12). Although major spine abnormalities associated with cloacal
exstrophy, such as lipomyelomeningocele and myelocystocele, should be identiable by ultrasound, MRI provides another opportunity to assess the fetal spine.
T2-weighted sequences are especially helpful in identifying the cerebrospinal uidlled component of complex closed spinal dysraphisms (Figs. 4.11 and 4.12).
Although the spatial resolution of MRI may not be optimal to identify subtle segmentation anomalies, MRI may help demonstrate the position of the conus medullaris, which will vary throughout gestation (Fig.4.11) [19, 20].
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E. R. Oliver and S. J. Back
Isolated Epispadias
Epispadias without bladder exstrophy represents a relatively minor malformation
on the EEC spectrum. Prenatal diagnosis can be particularly challenging and may
be overlooked, especially if the abnormality is mild or the external genitalia are not
adequately assessed [7]. Ultrasound ndings may include bid penis/clitoris, absent
genitalia, or simply an abnormal appearance of the external genitalia (Fig.4.13) [7,
21]. MRI may not be able to further characterize the abnormality due to the small
size of the involved anatomic structures and the modality’s lower spatial resolution.
Exstrophy Variants
Variant presentations of the bladder exstrophy—epispadias complex are rare, occurring approximately ten-fold less frequently than the classic forms [22]. The clinical
phenotypes of the exstrophy variants are wide-ranging, but a recent 40-year retrospective study from a high-volume center reported that the most common exstrophy
variants (excluding cloacal exstrophy) were skin-covered bladder exstrophy (also
termed “pseudoexstrophy”) and epispadias with bladder prolapse; these atypical
presentations accounted for 43% and 32% of the bladder exstrophy variants, respectively [23]. Variants of cloacal exstrophy also have been reported but are less common and reportedly accounted for 0.7% of cases in an older study from the same
institution [24].
The prenatal imaging appearance of exstrophy variants can be confusing. Indeed,
the identication of a uid-lled bladder in skin-covered exstrophy variants may
result in failure to consider exstrophy as a diagnostic possibility [25]. There is,
Fig. 4.9 24-week gestation fetus with cloacal exstrophy. (a) Transverse Color Doppler image of
the pelvis at the expected level of the bladder demonstrates a single left umbilical artery, consistent
with a two-vessel cord. No uid-lled bladder is present, and none was identied throughout the
course of the examination, consistent with bladder exstrophy. LT, left; RT right. (b) Sagittal grayscale image through the anterior abdomen demonstrates a large ventral wall defect with a covering
membrane (arrows) containing most of the liver and multiple loops of bowel, consistent with a
giant omphalocele. (c) A transverse grayscale image of the sacral spine reveals a uid-lled, thickwalled, and skin-covered spinal dysraphism. A small focus of echogenic tissue representing macroscopic fat is also present, and the ndings are consistent with a lipomyelomeningocele. (d)
Sagittal grayscale image through the lumbosacral spine shows a low conus medullaris terminating
at S2, consistent with a tethered cord. (e) Transverse grayscale image of the perineum demonstrates the absence of a normal anal “target” sign, consistent with imperforate anus (compare to
Fig. 4.2e), consistent with anorectal malformation. (f) Sagittal grayscale images of the pelvis also
conrm the absence of a normal rectosigmoid colon (compared to the Fig. 4.2f). The constellation
of anomalies is consistent with cloacal exstrophy (aka OEIS syndrome)
4 Prenatal and Postnatal Imaging of the Bladder Epispadias-Exstrophy Complex
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a
c
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d
e
f
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E. R. Oliver and S. J. Back
Fig. 4.10 KS. 30-week gestational age fetus with cloacal exstrophy. (a) Sagittal grayscale image
through the lower abdomen demonstrates an infraumbilical ventral wall defect (open arrows).
Although centered below the ACI, careful assessment reveals that the abdominal contents extend
into the base of the umbilical cord (UC), consistent with a small omphalocele. (b) Transverse
grayscale image through the ventral wall defect demonstrates a protruding tubular loop of bowel
(arrowhead), consistent with prolapsed ileum (“elephant trunk” sign) that may be observed in cloacal exstrophy. (c) Sagittal grayscale image of the lumbosacral spine demonstrates a low conus
medullaris terminating at L5. Segmentation anomalies of the lumbosacral spine were also present;
however, no ndings of a closed spinal dysraphism, such as lipomyelomeningocele or myelocystocele, were present. Spine anomalies associated with cloacal exstrophy may be mild or subtle as
in this case. Additional prenatal ndings consistent with cloacal exstrophy included non-visualized
bladder and small bowel-containing omphalocele (not shown). (d) Postnatal photograph of the
ventral wall defect demonstrates the prolapsed ileum (arrowhead) seen prenatally, which extends
between the two hemibladders (*) and below the small omphalocele (Om)
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4 Prenatal and Postnatal Imaging of the Bladder Epispadias-Exstrophy Complex
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Fig. 4.11 24-week gestational age fetus with cloacal exstrophy (same case as Fig. 4.9). (a)
Sagittal steady-state free precession image (TE/TR ms, 4.12/1.66) through the fetal body demonstrates a large membrane-covered ventral wall defect (arrowheads) containing most of the liver and
multiple loops of bowel, consistent with giant omphalocele. (b) Sagittal T1-weighted image (TE/
TR ms, 202/4.76) through the fetal body demonstrates the giant omphalocele containing the
T1-hyperintense liver and meconium-lled bowel loops; however, no T1-hyperintense meconium
is identied in the expected region of the rectum (circle), consistent with imperforate anus. (c)
Transverse fast-spin echo T2-weighted image (TE/TR ms, 1100/78) through the pelvis reveals
small skin-covered spinal dysraphism (open arrowhead), consistent with a lipomyelomeningocele.
Bowel loops extending into the omphalocele are partially visualized. (d) Sagittal oblique fast-spin
echo T2-weighted image (TE/TR ms, 1100/78) through the lower spine shows the conus medullaris (open arrow) terminating well below the inferior pole of the right kidney (arrow), in keeping
with a low conus medullaris. Normally, the conus medullaris does not extend below the lower
poles of the kidneys. A uid-lled bladder was not identied on this MRI examination or on ultrasound, consistent with bladder exstrophy. The constellation of ndings is consistent with cloacal
exstrophy (OEIS syndrome)
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E. R. Oliver and S. J. Back
Fig. 4.12 28-week gestational age fetus with cloacal exstrophy. (a) Sagittal fast-spin echo
T2-weighted image (TE/TR ms, 1100/76) through the fetal body demonstrates a moderately sized
membrane-covered ventral wall defect (arrowheads) containing a portion of the liver, consistent
with giant omphalocele. A complex spinal dysraphism is partially visualized (*). (b) Sagittal fastspin echo T2-weighted image (TE/TR ms, 1100/76) through the spinal dysraphism depicts the
large size and internal complexity of the defect. The combined MRI and ultrasound features were
consistent with lipomyelomeningocele. (c) Sagittal T1-weighted image (TE/TR ms, 202/4.76)
through the fetal body demonstrates the liver-containing omphalocele and the absence of T1 hyperintensity in the expected location of the rectum (circle), consistent with an imperforate anus.
T1-hyperintense components (arrows) are also present within the spinal dysraphism sac, consistent
with macroscopic fat and a lipomyelomeningocele. A uid-lled bladder was not identied on this
MRI examination or on ultrasound, consistent with bladder exstrophy. The constellation of ndings is consistent with cloacal exstrophy (OEIS syndrome). (d) Postnatal photograph demonstrates
two exstrophied hemibladders (*) between a bowel- and liver-containing omphalocele (Om) and
bid scrotum (arrows). A skin-covered spinal dysraphism and anal atresia were conrmed postnatally (not shown). A hindgut stula was also present below the left hemibladder (not shown)
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4 Prenatal and Postnatal Imaging of the Bladder Epispadias-Exstrophy Complex
Fig. 4.13 Isolated epispadias. (a) Sagittal grayscale image of the external genitalia of a geneti-
cally proven male fetus at 25weeks gestational age. There is a defect at the tip of the phallus
(arrow), which is dorsal to the penile urethra (mildly hyperechoic line denoted by open arrowheads). The external genitalia was recognized as being abnormal, however, a diagnosis of epispadias was not made. (b) Clinical photograph of the external genitalia demonstrates a dorsal defect
along the glans of the penis (arrow), consistent with epispadias and explaining the prenatal imaging ndings
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however, increasing recognition of the prenatal imaging ndings in these variants,
with multiple case reports now describing their imaging features [25–29]. Although
a bladder may be present, the appearance of the urinary bladder in cases of skincovered exstrophy variants is not normal. The bladder may extend into the base of
the umbilical cord and mimic an allantoic cyst [25, 29], extend beyond the normal
infraumbilical abdominal contour (Fig.4.14) [26, 27], or communicate with the
hindgut and contain echogenic debris [28]. Features common to almost all cases of
exstrophy variants are low abdominal cord insertions and pubic diastasis [23, 30],
and any abnormality of the bladder or other constellation of ndings seen with the
exstrophy spectrum should prompt assessment of the abdominal cord insertion,
symphysis pubis, and bony pelvis (Fig.4.14). The presence of a bladder anomaly
should also prompt careful assessment for anomalies associated with cloacal exstrophy (e.g., omphalocele, anorectal malformation, spine anomaly) (Fig. 4.14) to
ensure a more severe exstrophy variant is not overlooked.
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E. R. Oliver and S. J. Back
4 Prenatal and Postnatal Imaging of the Bladder Epispadias-Exstrophy Complex
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Postnatal Imaging Findings
Postnatal imaging of a child with EEC is done to understand their anatomy prior to
surgery and to assess postoperative changes and suspected complications.
Radiography, uoroscopy, renal scintigraphy, ultrasound (US), computed tomography (CT), and MRI each have a role in the care of these children. The type of imaging used depends on availability and the anatomic area of interest.
Urinary System
Although uncommon, congenital renal anomalies occur in a proportionally (1.6–9.1
times) higher number of patients with classic bladder exstrophy compared with the
general population [31]. Among those with EEC, they are more commonly associated with cloacal exstrophy. In keeping with the goal of preserved renal function
over the course of exstrophy repair, understanding the patient’s urinary tract anatomy at birth and monitoring for changes during bladder reconstruction and ureteral
reimplantation is of paramount importance. Renal size, location, and morphology
can be assessed by US at baseline and after interventions (Fig.4.15).
Complete primary repair of bladder exstrophy (CPRE) may expose the upper
urinary tracts to higher pressure earlier in life, which may contribute to urinary tract
dilation (UTD) and vesicoureteral reux (VUR). Bladder pressure and compliance
can be evaluated by video urodynamic studies, and UTD can be followed by renal
US.Even after CPRE, high-grade UTD is uncommon [32] (Fig.4.16). Similar to
children without EEC, VUR can be evaluated either by voiding cystourethrography
(VCUG) (Fig.4.17) or, where available, contrast-enhanced voiding urosonography
(ceVUS).
Fig. 4.14 30-week gestational age fetus with skin-covered cloacal exstrophy variant. (a) Sagittal
grayscale image of the lower abdominal wall demonstrates a thick-walled uid-lled defect
(arrowhead) extending anteriorly from the abdomen just below the ACI (open arrowhead). (b)
Transverse color Doppler image just below the level of the ACI reveals that the uid-lled structure is midline and bordered by both umbilical arteries (short arrows), consistent with an abnormal
bladder. (c) Transverse grayscale image of the iliac bones demonstrates attening of the iliac
bones, a nding typically observed in bladder exstrophy. (d) Sagittal grayscale image of the spine
demonstrates disorganized vertebral bodies (arrows) at T11, T12, and L1. (e) Sagittal fast-spin
echo T2-weighted image (TR/TE ms, 1100/78) demonstrates the uid-lled bladder and ventral
wall defect (arrowhead) inferior to the ACI (open arrowhead). (f) Sagittal T1-weighted gradient
echo images (TR/TE ms, 204/4.76) demonstrate a meconium-lled rectum (*) that does not extend
to the expected location of the perineum (arrow) but terminates abruptly with anterior angulation
(open arrow). Although no omphalocele was observed on the ultrasound or MRI, the constellation
of ndings was interpreted as representing skin-covered bladder exstrophy on the spectrum of
cloacal exstrophy (i.e., cloacal exstrophy variant). The diagnosis of a skin-covered cloacal exstrophy variant was conrmed postnatally