cloacal malformation.full
TRANSCRIPT
The Cloacal Malformation: Radiologic Findingsand Imaging Recommendations’
Diego Jaramillo, MD2 #{149}Robert L Lebowitz, MD #{149}W. Hardy Hendren, MD
441
The imaging studies and records of65 patients with the cloacal malfor-mation seen from 1969 to 1989 werereviewed. The malformations weredescribed according to cloacal con-figuration (urethral, vaginal), typeof uninary-cloacal communication(urethral, vesical), and level of rectalcommunication (vaginal, cloacal,vesical, other). Lower urinary tractabnormalities were frequent (reflux,ureteral ectopia, bladder diverticula,bladder duplication, urachal rem-nants, urethral duplication), as weregenital abnormalities (uterine du-plication, vaginal duplication, uter-inc atresia, vaginal atresia), abnor-malities of the bony pelvis (partialsacral agenesis, pubic diastasis), andrenal abnormalities (agenesis, ob-struction, horseshoe kidney). Con-
trast material studies of the cloacaand the distal limb of the colostomywith fluoroscopy in various projec-tions were essential for diagnosis.Voiding cystourethrography wasimportant for detecting vesicoure-teric reflux. Sonography was of lim-ited value for evaluation of the mal-formation but was valuable for im-aging the kidneys. MR imagingrevealed that spinal cord abnormali-ties cannot be predicted based onthe appearance of the lumbosacralspine and are more common thanpreviously thought.
Index terms: Anus, abnormalities, 757.1433.
Anus, imperforate, 757.1433 #{149}Bladder, abnor-
malities, 83.1469 #{149}Children, genitouninary sys-
tem, 80.1469 #{149}Genitourinary system, abnor-
malities, 80.1469 #{149}Infants, genitourinary sys-
tern, 80.1469 #{149}Magnetic resonance (MR), in
infants and children #{149}Rectum, abnormalities,
757.1433 #{149}Urethra, abnormalities, 851.1469.
Uterus, abnormalities, 854.1469 #{149}Vagina, ab-
normalities, 855.1469
Radiology 1990; 177:441-448
T HE cloacal malformation is a con-stellation of congenital abnor-
malities in which the urinary, geni-tab, and intestinal tracts convergeinto a common outflow structure, thecloaca (Latin for sewer). It is seen cx-clusively in phenotypic females (i)and occurs in one of every 40,000-50,000 newborns (2). The perineumof the typical patient has a singleopening that serves as the outlet forurine, genital secretions, and feces!meconium, and the abdominal wall isnormal (i) (Fig 1).
The term persistent cloaca has alsobeen used to describe this anomaly(3). In nonpiacental vertebrates suchas fish, amphibians, reptiles, birds,and monotremes, the cboaca is the or-gan for genitourinary and intestinalstorage and expulsion (4). A similarstructure is present in the human em-
bryo at 4 weeks (5). However, unlikethe structure in animals and humanembryos, the cboaca seen in the mal-formation is a channel rather than astorage chamber.
The cboacal malformation shouldnot be confused with exstrophy of
the cboaca, an entity having a similarname but differing greatly in em-
bryogenesis and clinical features. Ex-
strophy of the cloaca is seen in both
boys and girls, and there is a failureof closure of the lower abdominalwall (6).
In recent years, the prognosis ofinfants with the cboacal malfonma-
I From the Departments of Radiology (D.J.,R.L.L.) and Surgery (W.H.H.), Children’s Hos-pita!, Harvard Medical School, 300 LongwoodAve. Boston, MA 021 15. Received April 6, 1990;revision requested May 9; revision received
June 15; accepted June 22. Address reprint re-quests to R.L.L.
2 Current address: Department of PediatricRadiology, Massachusetts General Hospital,
Boston.
C RSNA, 1990See also the editorial by Wood (pp 326-327)
in this issue.
tion has improved significantly, and
surgical repair with good functionaloutcome is now possible (7-9). Ade-quate surgical planning requires pne-cisc preoperative definition of theabnormal anatomy by means of imag-ing studies and cystoscopy. Preven-tion of renal damage, which is themost significant potential cause ofmorbidity in these patients (9), re-quines detection and treatment of uri-nary tract obstruction and reflux,plus early diversion of the fecalstream by means of a colostomy. Ad-ditionally, radiology has an impor-tant role to play in discovering andcharacterizing coexisting anomaliesin other organ systems.
Herein we describe our experiencewith 65 female infants and childrenwith the cloacal malformation seen atour institution during the past 20years. We will describe the spectrum
of the malformation; the genitouri-nary, intestinal, lower spinal cord,and pelvic wall abnormalities that oc-cur in close association with the mal-formation; the extrapelvic abnormali-ties that coexist; and the approach toimaging.
MATERIALS AND METHODS
We reviewed the imaging, clinical, cys-toscopic, and surgical findings in 65 fe-
male subjects (newborn to 21 years of age)with the cloaca! malformation seen at ourhospital during the years 1969-1989. Atleast one of us participated in the evalua-tion of every patient, and one of us pen-formed surgery in all but four of them.
We imaged 28 patients before repair ofthe cloacal malformation. Their ages atexamination ranged from 1 day to 4 years(except for one patient evaluated whenshe was 1 1 years old). Twenty-five ofthese 28 patients had undergone divert-ing colostomy prior to imaging. All 28 pa-tients had undergone one or more fluoro-scopically monitored injection studies us-ing water-soluble contrast material forevaluation of the malformation (26 injec-
tions into the perineal opening, 17 injec-tions into the distal limb of the colosto-
a.
Urethral Vaginal
I
R
b.
Figure 2. (a) Cloacal configuration. Sagittal diagrams show the narrow urethral configura-
tion (left) and the wide vaginal configuration (right). Vagina can often be identified by the
cervical impression. Sacrum is short, a frequent finding in the malformation. (b) Urethral
configuration. Contrast material was injected into a catheter in the cloaca with use of a nip-
ple for occlusion (straight arrow). Cloaca is long and narrow and communicates with theurethra and the rectum (R). A small chamber lies between the cloaca and the rectum (solid
curved arrow). Vaginal lumen is not opacified (open curved arrow) but is distended. Vagina
indents the bladder (B) and rectum (R). (c) Vaginal configuration. A wide, short cloaca hasbeen opacified. Two vaginas (V) are present, one of which is partially hidden by the bladder.
The communication with the rectum is not opacified.
C.
442 #{149}Radiology November 1990
Figure 1. Perineum of a patient with do-
acal malformation. Featureless or blank pen-neum has a single penineal opening, and the
anus is absent.
my, and 10 injections through catheters
placed intraoperatively or into vesicos-tomy on vaginostomy stomas) and at least
one study of the upper urinary tract (15sonographic, 15 excretory urographic,and eight scintigraphic studies). Nine pa-tients in this group underwent magnetic
resonance (MR) imaging for evaluation ofthe lower spinal cord.
The other 37 patients were seen follow-ing some degree of repair of the cboacalmalformation performed elsewhere.
Their imaging studies were reviewed,and often new ones were performed.
The surgical treatment of these patientshas been reported elsewhere (7,8).
RESULTS
We described the cboacal malfor-
mation according to its radiobogic ap-
peanance. The following categoriza-
tion of the malformation, which is
based on radiologic findings, is an at-
tempt to serve as a guide to the radi-
ologist performing the imaging stud-
ies. The categorization is indepen-
dent of, but complementary to, the
classification of the level of conflu-
ence of the cboacal malformation
based on cystoscopic and operative
findings (7).
The cloacal configuration (Fig 2a)
was categorized as either urethral (34patients [52%] or vaginal (31 patients
[48%)] . The former was a narrow, of-
ten long and curved cloaca with a
small penineal opening that tended
to be a continuation of the urethra
(Fig 2b). The latter was a wide, usual-
ly straight cloaca that tended to be a
continuation of the vagina (Fig 2c).
The type of uninary-cloacal com-
munication (Fig 3a) was urethral in
50 patients [77%]; in these patients
there was a well-formed urethra, usu-
ally with a normal sphincter, joining
the bladder to the cboaca (Fig 3b). The
communication was vesical in 15 pa-
tients (23%); the urethra was absent,
and there was direct communication
between the bladder and the cloaca
(Fig 3c).
The level of rectal communication
(Fig 4a) was categorized as vaginal
(44 patients [68%]), cloacal (seven pa-
tients [11%]), or other (ten patients
[15%]). Vaginal communication usu-
ally occurred at the posterior wall of
the lower vagina, or, in cases of vagi-
nab duplication, at the lower end of
the vaginal septum (Fig 4b, 4c). Less
frequently, the communication oc-
curred higher in the vagina. In two
cases the communication was with
the anterior wall (Fig 5a, 5b). In cases
of cboacal communication, there was
direct communication between the
rectum and the cloaca. In five cases,
there was a tiny chamber acting as a
passageway between the rectum and
the cloaca (Fig 2b). Three of these
five patients had a separate, blind-
ending vagina, distended with geni-
tal secnetions (Fig 2b). In five other
patients, communication occurred
between the intestine and the blad-
den when there was either no vagina
or when the vagina was malposi-
tioned (Fig 6). These five also had pu-
bic diastasis.
In four cases the rectum opened
onto the perineum through an ante-
riorly malpositioned anus (cboacal
variant, Fig. 4a). In one patient there
was a rectouterine communication.
Four patients (6%) had had prior
Lirethro-cloacal Vesico-cloacal
V
B
‘.�.
Vaginal Cloacal
b. C.
Volume 177 #{149}Number 2 Radiology #{149}443
pull-through operations elsewhere,
and the level of the communication
could not be determined.
Abnormalities of the pelvic struc-
tunes were common (Table 1). Three
patients had an accessory urethra
that exited just below a clitonislike
structure (Fig 7a). This “phallic
urethra” (2) was very small. There
was a second, larger, more normalurethra located posterior and inferior
to it (Fig 7b). Imaging studies, uro-
dynamic examinations, and operative
findings showed that the urinary
sphincter was located around the
urethra in 37 patients (57%) and
around the cboaca in 14 (22%). Four-
teen (22%) had no sphincter.Diverticula of the bladder were
seen in 13 patients (20%). All six pa-
tients with peniuretenal diverticulahad reflux. Patients with either du-
plication of the bladder or a common
vesicovaginal or vesicocecal chamber
,�,, .� , � �,J.
always had pubic diastasis (generally
wider than 4 cm) and severe genitaland rectal abnormalities (Fig 8). Morethan half of the patients had uretenal
reflux, usually bilateral (22 of 39
cases). Uretenal ectopia was frequentand ranged from lateral or inferiorlocation of the ureteral orifice in the
bladder to insertion in the vagina(five patients) or the cboaca (one pa-tient).
Duplication of the uterus, usually
associated with vaginal duplication,was seen in 36 patients (55%) (Figs 2c,4c, 5b, 8, 9). Obstruction of the geni-tab tract was present in 16 patients
(25%) and usually was at the level ofthe vagina. Patients with obstruction
frequently had hydrometrocolpos atbirth (14 of 16 cases). Two patientsdeveloped hematocolpos at puberty,and one presented at age 16 with bi-
� Figure 3. (a) Diagrammatic representationof the types of urinary-cloacal communica-tion. The communication is called urethro-cloacal when a well-formed urethra joinsthe bladder to the cloaca (left). If the urethrais absent or rudimentary, the communica-
tion is called vesicocloacal (right). (b) Ureth-
rocloaca! communication. Contrast materialhas been injected into a cloaca by means ofthe nipple-occlusion technique. There is ret-rograde filling of the urethra (straight an-
row), which is opacified only to the level of
the urinary sphincter, indicating that the
sphincter is competent. The vagina (V) andrectum (R) are also opacified. The rectoc!oa-cal communication is very narrow (curvedarrow). The bladder (B) is faintly opacified.
(c) Vesicoc!oaca! communication. There is
opacification of a cloaca with vagina! config-uration that communicates freely with both
the vagina (V) and the bladder (B). There is
no urethra. The rectum is not opacified.
c�#{231}�
:� #{149}‘� j���Uro enitol Sinus
�‘ . � with �nteriorty Ptoced Anus
. - � .. � Cloocol Variant)
Figure 4. (a) Diagrammatic representation of the level of rectal communication. The rectum usually joins the vagina low on its posterior
wall (upper left). The rectum can also join the cloaca (upper right). In the so-called cloacal variant (lower illustration), the rectum drains
through an anteriorly placed anus, very close to the opening of the urogenital sinus. (b, c) Low rectovaginal communication. The bladder
(which contains an air-filled urinary catheter balloon), vaginas (V), and rectum (R) are opacified by simultaneous injection into the suprapu-bic bladder catheter and the distal limb of the colostomy. (b) Lateral projection. The communication (arrow) is between the rectum and the
lower portion of the superimposed vaginas. (c) Frontal projection. The communication (arrow) is into the incomplete septum that divides
the vagina into two chambers inferior!y.
444 S Radiology November 1990
lateral adnexal masses that were
found to be dilated fallopian tubes in
an otherwise atretic genital tract.
Eleven patients had abnormal sep-
aration of the pubic symphysis (Fig
8). Of eight patients with a diastasis
greater than 2 cm, six had no cvi-dence of a functional urinary sphinc-
ten, and four had a common vesicova-
ginal chamber.
Some degree of sacnal agenesis was
seen in nearly half of the patients (26
of 65 [40%]). Spinal anomalies in-
cluded dysraphism, segmentation
anomalies, and spinal stcnosis.
The most frequent abnormality of
the spinal cord was tethering. A
high, stubby conus was seen in twopatients, each of whom had segmen-
tal sacral agcnesis. More than half of
the cases of spinal cord anomalies
were detected since we began to use
MR imaging as a screening tool. Of
16 patients who underwent MR im-
aging, seven had some degree of spi-
nal cord abnormality. Of the six pa-
tients with tethered cord, three had
only minimal sacral abnormality, and
in one the sacrum was normal.
Multiple abnormalities of the cx-
trapelvic organs were seen (Table 2).
Seven of nine patients with only one
kidney had significant genital anom-
alies. However, only one of the seven
had ipsilatenal atnesia of a duplicated
genital tract. Only eight patients had
congenital anomalies of the upper
urinary tract that required surgery
(six with obstruction at the uretero-
pelvic junction and two with obstruc-
tion at the ureterovesical junction).
Congenital heart disease, although
rare, was the cause of the only two
deaths.
DISCUSSION
A cow with a malformation result-ing from confluence of the urinary,
genital, and alimentary tracts was de-
scnibed by Aristotle (10). In 1692, Sa-
viard performed an autopsy on an in-
fant who had died several days after
birth who had “no apparent marks of
either [sex] externally, . . . two kid-
neys fastened together . . . [which]
discharged . . . into a large hole, the
Cystis Communis, . . . whose aperture
was the only one external.” By using
a blow-pipe introduced into the “cys-
tis,” has was able to inflate the com-
municating structures and “found
two small wombs, . . . each [with] a
short vagina . . . which evacuated ...
into that cystis, and this, to speak the
truth, was only the extremity of the
rectum a little dilated.” Saviard ends
his description with an insightful
Figure 5. Anterior rectovagina! communication. Curved arrows = cervical impression.
(a) Oblique projection. The rectum (R) passes over the vagina! septum to joint the lower por-
tion of the vagina (V) on its anterior wall (straight arrows). B = bladder. (b) Frontal projec-
tion. A midline septum separates two vaginas, and a cervical impression is seen at each apex
(curved arrows).
Figure 6. (a) Frontal projection. This patient had a partially duplicated bladder (B) into
which the rectum (R) drained. (b) Lateral projection. The vagina (V) has two cervices (an-
rows) and is infeniorly malpositioned. The cloaca has a urethral configuration. Confusing
anatomy in this patient necessitated four imaging examinations. The last was performed
with the patient under anesthesia during cystoscopy; contrast material was injected through
catheters placed at that time.
Figure 7. (a) Diagrammatic representation of urethral duplication. A narrow accessory on
“phallic” urethra opens onto the perineum just beneath a large clitoris. The functional, more
posterior on ventral urethra joins the cloaca. (b) A narrow, dorsal accessory urethra (arrow)
that exits beneath the clitoris is opacified, as is a wide ventral urethra that merges with the
cloaca. The vagina is not opacified. B = bladder, R = rectum.
No.ofPatients
Lower urinary tractUrethra
Accessory or “phallic” urethraAbsent or poorly developedAtresia or obstruction
BladderDiverticulaDuplicationUrachusCommon vesicovagina! chamberHypoplasia
Lower ureter and ureterovesica! junctionReflux
Grade 1Grade 2Grade 3Grade 4Grade 5
EctopiaGenital tract
VaginaDuplicationAgenesis or atresiaHydrometrocolpos at birthHematometrocolpos at puberty
UterusDuplicationAgenesis
Adnexa (surgical data)Absent or hypoplastic ovariesParaovanian and fallopian tube cystsCystic ovaries
Pelvic osseous structuresSacral agenesis or hypoplasiaPubic diastasisDysraphism
Lower spinal cord (data from 16 MR studies, seven abnormal)Tethered cordLipomyelomeningoceleHigh cord
Retrorectal presacral spaceRectal diverticulumPresacra! dermoidSacrococcygeal teratoma
3(5)4(6)5 (8)
13 (20)6 (9)5(8)5 (8)3 (5)
39 (60)*0
10575
18 (28)t
30 (46)16(25)114(22)
2 (3)
36 (55)10(15)
4 (6)
3 (5)2 (3)
26(40)11 (17)
9(14)
8(12)t3(5)11
2(3)1l
1 (2)1 (2)1 (2)
Note-Percentages in parentheses.
* Twenty-two bilateral cases. The grade of reflux was unavailable in 12 of the 39 patients.
t Five extravesical cases.I Includes four with rudimentary vaginal chambers.
§ Six cases found with MR imaging.1 One case found with MR imaging.
Figure 8. Bladder duplication. Frontal pro-
jection shows two hemibladders (B), each
having its own refluxing ureter, and wide
pubic diastasis. Two vaginas (V) are partially
obscured by the left hemibladder.
Volume 177 #{149}Number 2 Radiology #{149}445
Table 1Abnormalities of the Pelvic Structures
Structure
statement about the cboacal malfor-
mation that is still valid: “It is very
probable . . . that if this child had
lived to be adult, it would have been
incapable of generation from the
mixture of the seed with the stercoral
and urinary excrements. Besides,
both these excrements would have
had an involuntary exit.” In the early
19th century Meckel introduced the
term “cloaca congcnita” to describe
the malformation (10).
The embryologic basis of the mal-
formation is still a subject of contro-
versy (5,1 1-14). What follows is a
brief summary of the most widely ac-
cepted theories. The cboacal malfor-
mation is believed to result from fail-
ure of the urorectal septum to join
the cloacal membrane during the 4th
to 6th weeks of embryonic develop-
ment. This failure could result in a
persistent communication between
the rectum and the urogenital sinus.
The cboacal membrane, which covers
the perineum at this stage, cannot
rupture if it is not joined by the uro-
rectal septum, so the normal penineal
openings do not develop. Further-
more, abnormalities in cboacal septa-
tion and urogenital sinus formation
interfere with normal mesonephric
and paramcsonephnic duct develop-
ment. This may explain the very fre-
quent association of the cloacal mal-
formation with duplication or agene-
sis of genital structures and with the
less frequent but still common anom-
alies of number and position of the
kidneys. As with imperforate anus,
primary obstruction of the rectum
with secondary formation of commu-
nication between the rectum and ad-
jacent structures has also been postu-
bated and helps to explain some of
the unusual connections (13) (Fig 5).
The multiplicity of associated find-
ings, particularly in the lower spinal
cord, lumbosacral spine, and bladder,
suggests that more complex and
probably multiple disturbances have
occurred during the process of devel-
opment of the caudal pole of the em-
bryo (15,16).
The few cases that are intermediate
between the cloacal malformation
and cboacal exstrophy are puzzling.
Abnormal separation of the pubic
symphysis, previously thought to be
characteristic of exstrophy of the
bladder or the cboaca, has been found
in association with other genitouri-
nary anomalies (17) and was present
in 1 1 of the patients in this series.
Two of these patients had a vesicoce-
cal communication, reminiscent of
the visceral configuration of cloacal
exstrophy. Failure of regression of
the cloacal membrane has been sug-
gested as one causative factor in both
the cloacal malformation and cboacal
exstrophy; however, in cloacal cx-
strophy, the cloacal membrane be-
comes interposed between the fusing
genital tubercles and interferes with
the normal closure of the anterior
pelvic wall (6,18). It is likely that this
process operates to some degree in
the cases of the cloacal malformation
with features of cloacal exstrophy.
A small group of patients had
esophageal atresia (11%) and other
features of the VATER association
(vertebral, anal, tracheoesophageal,
and radial and renal defects), but
they had lower-limb anomalies and
not radial abnormalities.
Until about 20 years ago the cboacal
malformation was an embryologic
curiosity, rarely reported (3,16,19)
and having devastating effects and a
Figure 9. Vaginal duplication. Two distended vaginas (1/) separated by an incomplete sep-
tum are we!! demonstrated by (a) the injection studs’ and (b) sonography. Sonogram is on-
Upper urinary tractUnilateral renal agenesisUreteral obstructionAbnormalities of rena!
position and rotationHorseshoe kidneyDuplication of collecting
system
Gastrointestinal tractEsophageal atresiaMeckel diverticulumMalrotationIntestinal atresiaMeconium peritonitis,
without bowelperforation
Cardiovascular systemVentricular septal defectTetra!ogy of Fallot
Musculoskeletal systemVertebral anomaliesLower-limb anomaliesCongenital hip dysplasia
Head and neckCraniofacial anomaliesHydrocephalus
9(14)’8 (12)t
6(9)4(6)
4 (6)
7(11)
6(9)5(8)3 (5)1
2(3)
6(9)2(3)
13 (20)5(8)
4 (6)
6(9)2(3)
Note-Percentages in parentheses.
- Seven with significant genital anomalies.
, Six ureteropelvic junction. six ureterovesi-cal unction.
I Two duodenal.
.�,,.i,., �
Figure 11. Same patient as in Figure 4b
and 4c. The bladder (B), vagina (V), and
uterine horns (arrows) are opacified.
446 . Radiology November 1990
ented to correspond to the vaginogram.
grim prognosis (20,21). In a series as
recent as 1959 (3), the mortality was
greater than 50% because of urosep-
sis, renal failure, and cardiovascular
anomalies.
Today, however, repair of the mal-
formation and management of its
complications have become possible.
Death is very rare, and the morbidity
related to the urinary and intestinal
tract has been markedly reduced,
mainly due to the recognition of the
importance of early colostomy to di-
vent the fecal stream and decompres-sion of the urinary tract. A divided-
loop right-transverse colostomy to
avoid fecal contamination of the
urine is preferred for reasons out-
lined previously (8). Intermittent
catheterization of the cloaca is often
necessary in the neonatal period to
drain urine from the distended vagi-
na(s). Vaginostomy or vesicostomy
arc almost never needed. Correction
of severe reflux is often performed
prior to definitive repair of the mal-
formation. The definitive repair is
complex and involves the separation
of the rectum, vagina(s), and urinary
tract, bringing each to the perineum
in a more normal fashion. The poste-
nor sagittal approach is preferred
(8,9). Functional repair of the cloacal
malformation can result in a conti-
nent bladder and rectum, and in a va-
gina of near anatomic configuration.
The outcome of repair of the genital
tract is difficult to assess at this time
because most survivors arc only now
reaching the reproductive age (8,9).
The first step in the management
of the malformation is the perfor-
mance of a diverting colostomy in
Table 2
Extrapelvic Abnormalities
the immediate postnatal period in or-den to prevent fecal contamination of
the urinary tract (8,9). Since the state
of the urinary tract is the main factor
deciding the prognosis of patients
with the cboacal malformation (9), de-
tection of reflux and obstruction
should be done early. Imaging stud-
ies to define the cloacal anatomy be-
fore planning the definitive repair
can then be performed electively.
Further imaging should include
b.
Figure 10. (a) Frontal radiograph shortly
after delivery shows a large pelvic mass oc-
cupying most of the lower abdomen. There
is a linear calcification in the abdomen (an-
row) suggestive of meconium peritonitis.The sacrum is hypoplastic, and there is wide
pubic diastasis. (b) Sagittal sonogram of the
same infant shows a vagina with a fluid-
debris level. The compressed bladder (an-row) is located anteriorly.
studies to detect and characterize as-
sociated anomalies.
Every newborn girl with imperfo-
rate anus and a single penineal open-
ing should be considered to have the
Volume 177 #{149}Number 2 Radiology #{149}447
cloacal malformation until provedotherwise. Just as there is wide varia-tion in the internal anatomy, there isa spectrum of severity in the appear-ance of the abnormal perineum. Fig-ure 1 shows the typical cboacal anato-my. However, in some cases the in-troitus may have a more normal
appearance, and in others there is arudimentary phalliclike structure
with poorly formed labia.
Imaging evaluation should begin
with plain radiognaphs. A pelvicmass is almost always a distended va-
gina and/on uterus, secondary to ob-struction (Fig 10). The level of thisobstruction determines whether thevagina is only distended by genitalsecretions on whether it containsurine and meconium as well. If themass contains gas, the gas is mostlikely from the colon and is a sign ofrectovaginal communication (22).Linear calcifications in the abdomenalong the peritoneal surfaces indicatecalcified meconium from meconiumperitonitis (Fig 10). This can occur inpatients with the cboacal malfonma-tion when meconium spills into theperitoneal cavity via the fallopiantubes and not necessarily from intes-
tinal perforation (23). Granular calci-fications in the abdomen correspond-ing to the course of the colon suggestcalcified intnaluminal meconium,which can occur when there is mix-ing of urine and meconium in the lu-men of the colon. This is more likelyin patients with the cboacal malfor-mation when there is vaginal atresiaon stenosis and rectovesical or nec-tounethral communication. Severediastasis of the pubic symphysis sug-gests poor development of the une-thral sphincter, rectovesical commu-
nication, or a common vesicovaginal
chamber.Injection studies with fluonoscopic
monitoring are the most importantpart of the nadiobogic evaluation ofthe cboacal malformation. Cross-sec-tional imaging techniques are notusually helpful because the multiplestructures involved and the unpre-dictable and erratic courses of thecommunications between them donot lend themselves well to studiesin orthogonal planes. The structuresare readily accessible for catheteriza-tion, and studies with contrast mate-nial also provide functional infonma-tion about reflux and continence. Se-
dation is usually not necessary.If the single perineal opening is
small, catheterization can usually be
accomplished with an 8-F feedingtube. If the opening is patulous, it
should be partially occluded with a
nipple (Poznanski technique) (24)(Figs 2b, 3b) or with the balloon of aFoley catheter.
Accessory penineal openingsshould be so�ht. A tiny opening atthe base or the tip of the clitoris isusually the opening of a second ure-thra, sometimes called a phallic ure-thra. As in urethral duplication inmales, this uppermost (dorsal) ure-thra is usually rudimentary, whereasthe lower (ventral) urethra is themore functional of the two (25).
Imaging during injection of con-trast material into the cloacal open-ing should begin in the lateral pro-jection to display the various commu-
nications optimally. Examination inthe frontal projection is important forshowing vaginal and bladder dupli-cation (Figs 4c, 5b, 8, 9). For all injec-tion studies, water-soluble contrastmaterial (17% meglumine diatrizoate)is preferred over barium because ofthe possibility of reflux into the up-per urinary tract on flow into theperitoneal cavity, because repeatedinjections are more readily done, andbecause rarely (in one case in our se-ries) barium may fail to demonstratea narrow communication that lessviscous water-soluble contrast mate-
rial shows.It is important to distinguish be-
tween the bladder and vagina, but
this can be difficult (Figs 4b,10). Inone case initially treated elsewhere,this confusion led to performing avaginostomy instead of the plannedvesicostomy. Reflux into a ureter orinto a urachal remnant helps to iden-tify a structure as the bladder. A cen-vical impression, which is not alwayspresent, and a septum help to identi-fy the vagina (Figs 5, 6b). The posi-tion of a structure is not always a clueas to its identity (Fig 6b).
Failure to opacify the bladder, ifthe retrograde injection of contrastmaterial stops at the urethral sphinc-ten, indicates that the sphincter iscompetent (Fig 3b). Failure to opacifythe vagina may indicate either vagi-nab atresia or obstruction (Fig 2b). Ifthe obstruction is untreated, and thepatient has a uterus, she may develophematocolpos at puberty. During do-acal injection, the rectum often failsto opacify. This occurred in 15 of 28patients studied by us prior to repair.Opacification of the endometrial cay-ity is extremely rare (the uterus wasseen in only two of these 28 patients)(Fig 11).
Following injection into the cloaca,an attempt to advance the catheterinto the bladder should be made inorder to perform a voiding cystoure-
throgram. Vesicoureteric reflux can-not be detected and characterizedwithout a cystogram. Catheterizationof the bladder may be difficult, evenwith a coud#{233}catheter. In a few casesthe catheter can be placed in thebladder only at the time of cystos-copy.
In patients who have already had acolostomy, injection into the distallimb of the colostomy should bedone. We usually do this as the firstinjection study because, if all of thepelvic structures are shown, a cboacalinjection is not needed. Injection intothe distal limb of the colostomy regu-larly demonstrates the level of therectal communication and distin-guishes the rectum from the vagina.This differentiation can sometimesbe difficult during the cboacal injec-tion, particularly when the vagina isdistended and the rectum is poorlyopacified (Fig 3b).
Sonographic evaluation of the pd-vic viscera can occasionally help
characterize the cloacal malforma-tiort, particularly when the vagina is
dilated (Figs 9, 10). However, in thisseries, sonography was useful forevaluation of the pelvic structures in
only one-third of patients, primarilydue to difficulty in obtaining a fullbladder to use as an acoustic window.
We evaluate the upper urinarytract initially with ultrasound (US)and later with a functional urogna-phic or scintigraphic study. If thesonogram is normal, either scintigra-phy or excretory urognaphy is used.If the sonogram is abnormal, we useexcretory urography because preciseanatomic definition is so importantin this complex malformation.
Since the prevalence of anomaliesof the lower spinal cord is very high(43% in the patients evaluated withMR imaging) and since the plain ra-diographs correlate poorly withpathologic features of the cord, wenow evaluate the lower spinal cordin every patient with the cboacal ma!-formation. This can be done with US
during the neonatal period, or withMR imaging later (16).
Postoperative MR imaging forevaluation of the adequacy of the nec-tal pull-through (26) can be done si-multaneously with the examination
of the cord, as was done in six of 16patients. MR evaluation of the uterusand ovaries was not helpful. Thismay be related to two factors, thatmost patients were examined in in-fancy and that these structures werefrequently hypoplastic and located inabnormal positions. Evaluation of ab-normalities in other organ systems is
448 #{149}Radiology November 1990
guided by the physical examination.In summary, the cboacal malfonma-
tion represents a spectrum of abnor-malities of the lower urinary, genital,and intestinal tracts. Knowledge ofthe main anatomic patterns before ra-diobogic investigation is important.Injection studies with fluoroscopicmonitoring in the awake child arcthe mainstay of radiobogic evalua-tion. They are a challenge to performand interpret. Coexisting anomaliesare frequent and often important,and they should be sought. #{149}
Acknowledgments: We thank Diane de Al-derete for secretarial assistance, Donald Sucherfor the photography, and Jean Kanski Bitt! forthe drawings.
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