DOI:10.2214/AJR.05.0117
AJR 2006; 187:1034-1035
© American Roentgen Ray Society
Combining MDCT, Micturating Cystography, and Excretory Urography for 3D Imaging of Cloacal Malformation
Matthew E. Adams1,
Melanie P. Hiorns2 and
Duncan T. Wilcox3
1 Hammersmith Hospital, London, United Kingdon.
2 Department of Radiology, Great Ormond Street Hospital, London, United Kingdom
WC1N 3JH.
3 Children's Medical Center, Dallas, Texas.
Received February 2, 2005;
accepted after revision March 22, 2005.
Address correspondence to M. P. Hiorns
(hiornm{at}gosh.nhs.uk).
Keywords: cloacal malformation • congenital malformations • CT • genitourinary tract imaging • pediatric imaging
Introduction
Cloacal malformation is a rare anomaly occurring exclusively in
genotypically female infants with an incidence of one in 50,000 births
[1]. It represents the
persistence of an early stage of embryonic development in which the urinary,
genital, and gastrointestinal tracts remain confluent, all draining via a
common channel to a single perineal orifice. However, the range of
malformation varies greatly among individual patients, and the challenge for
the radiologist and urologist is to define the anatomy accurately to allow
reconstruction to be planned. Conventionally, imaging has involved a series of
different studies each aimed at delineating part of the complex anatomy. Often
the exact configuration of the different elements only becomes apparent during
surgical exploration. We report a case in which a micturating cystogram and
excretory urogram were performed simultaneously with thin-section MDCT, which
to our knowledge is a new technique. Subsequent reformatting allowed accurate
3D representation of all the urogenital and hindgut components and
connections, thereby greatly enhancing surgical planning.
Case Report
An 8-month-old girl with a loop colostomy that had been fashioned at birth
and with urinary drainage via a single perineal orifice, attended the
radiology department for imaging in preparation for elective reconstruction of
a cloacal anomaly. A micturating cystogram was performed via the single
perineal orifice. This procedure revealed an ellipsoid cavity believed to be
the vagina, a smaller anterior cavity that was possibly the bladder, a
tortuous structure thought to represent the left ureter, no right ureter, and
a loop of distal bowel. The sonogram showed a malrotated right kidney and a
tiny cystic left kidney, a cystic structure in the pelvis, and possibly two
ovaries. The uterus was not positively identified.
To further delineate the anatomy, the infant was taken to the CT scanner
(Sensation 16, Siemens Medical Solutions) two days later, and a contrast
medium (Omnipaque 140, Amersham Health) was instilled into the pelvic cavities
via a catheter passed into the perineal orifice. The volume of contrast
material used was the same as for the previous micturating cystogram to
opacify all pelvic cavities. Omnipaque 300 (3 mL/kg) was then given IV, per
our protocol for an excretory urogram, to delineate the collecting and
drainage system of the urinary tract. Five minutes later, additional contrast
material was given via the perineal catheter to allow leakage, and CT of the
abdomen and pelvis was performed using a slice thickness of 1.5 mm and a
low-dose technique. Images were reconstructed using Siemens Medical Solutions'
Leonardo workstation and software to produce multiplanar and surface-shaded 3D
images. Manipulation of the 3D images was used to enable visualization from
any angle and to show many of the tortuous structures and abnormal connections
(Figs. 1A and
1B). The reconstructions showed
that the vagina was the main fluid container in the pelvis. The bladder lay
anterior, communicating with the vagina via a narrow channel. The bowel
inserted into the anterolateral aspect of the vagina. A normal-size right
kidney was seen in an anatomically normal position with contrast outlining the
renal parenchyma and collecting system. Drainage of the right kidney was
complex, with upper and lower pole calyces draining via separate pelves into a
non-dilated ureter, which terminated on the anterolateral aspect of the
vagina. A second tortuous, intermittently dilated right ureter was seen
originating from the confluence of the pelves with drainage into the posterior
aspect of the vagina. The left kidney was small and served by a single ureter
draining to the anterior vagina. These findings were confirmed at the time of
surgery.
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Fig. 1A —8-month-old girl with cloacal malformation. Also see Figures
S1C and S1D, cine loop, in supplemental data online. Three-dimensional
reconstruction with surface shading showing genitourinary tract.
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View larger version (62K):
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Fig. 1B —8-month-old girl with cloacal malformation. Also see Figures
S1C and S1D, cine loop, in supplemental data online. Composite image of
genitourinary tract showing four multiple projections. Orientation is
indicated by colored cube adjacent to each image. Images can be presented as
fully manipulable 3D object on workstation.
|
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Discussion
The antenatal diagnosis of cloacal anomalies with sonography
[1] and MRI
[2] is well described.
Postnatal imaging for preoperative assessment is usually performed as a series
of investigations including sonography, micturating cystogram, excretory
urogram, conventional CT, and MRI
[3]. Integration of the
information obtained is difficult, and even with cross-sectional imaging in
multiple planes, interpretation is challenging. As a result, road maps to
guide the surgeon in preoperative planning are often incomplete, with the
exact nature of the complex anatomy only becoming apparent after lengthy
explorative surgery. In this case, we used a novel technique combining
descending and ascending contrast medium examinations with MDCT to produce an
accurate and easily assimilated depiction of the anatomy of cloacal
malformation. This technique allows the radiologist and surgeon to fully
examine the complexities of the anomaly before surgery, providing information
for improved preoperative planning and potentially more accurate
reconstruction, while reducing the overall length of the surgical
procedure.
References
- Warne S, Chitty LS, Wilcox DT. Prenatal diagnosis of cloacal
anomalies. BJU Int 2002;89
: 78-81[Medline]
- Veyrac C, Couture A, Saguintaah M, Baud C. MRI of fetal GI tract
abnormalities. Abdom Imaging 2004;29
: 411-420[Medline]
- Nievelstein RA, Vos A, Valk J, Vermeij-Keers C. Magnetic resonance
imaging in children with anorectal malformations: embryologic implications.
J Paediatr Surg 2002;37
: 1138-1145[CrossRef][Medline]
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Introduction
Case Report
