AJR 2001; 176:641-645
© American Roentgen Ray Society
Defecographic Measurements of Rectal Intussusception and Prolapse in Patients and in Asymptomatic Subjects
Fabio Pomerri1,
Monica Zuliani,
Cecilia Mazza,
Felipe Villarejo and
Angela Scopece
1
All authors: Department of Medical Diagnostic Sciences and Special Therapies,
Radiology, University of Padua, Via Giustiniani 2, 35128 Padua, Italy.
Received June 27, 2000;
accepted after revision August 28, 2000.
Address correspondence to F. Pomerri, Dipartimento di Scienze
Medico-Diagnostiche e Terapie Speciali, Radiologia,
Università di Padova, Via Giustiniani 2, 35128
Padova, Italy.
Abstract
OBJECTIVE. The aim of this study was to provide measurements for the
defecographic diagnosis of rectal intussusception and rectal prolapse.
MATERIALS AND METHODS. Four hundred thirty-seven consecutive
patients with defecation and micturition disorders and gynecologic complaints
were studied by means of defecography (120 patients), colpodefecography (17
patients), or cystocolpodefecography (300 patients). As a control group, 43
asymptomatic subjects underwent defecographic examination.
RESULTS. Thirty-five patients were found to have rectal
intussusception and 18, to have rectal prolapse. Anterior and posterior rectal
wall folding thickness, intussuscipiens diameter, intussusceptum lumen
diameter, and the ratio between the intussuscipiens diameter and the
intussusceptum lumen diameter were measured in all patients. The findings were
compared with those obtained in 13 of 43 asymptomatic subjects with rectal
outline changes mimicking intussusception. Rectal folding thickness and the
ratio between the intussuscipiens diameter and the intussusceptum lumen
diameter were significantly greater in subjects with rectal intussusception
and rectal prolapse than in asymptomatic subjects with rectal mucosa
folding.
CONCLUSION. Our findings suggest that dynamic evacuation radiology
contributes to making a differential diagnosis between rectal intussusception
and mucosal folds in the rectum.
Introduction
In their study published in 1984, Mahieu et al.
[1] listed five quantifiable
morphologic signs as criteria for considering a defecographic picture to show
normal findings: increase of anorectal angle, obliteration of the impression
of the puborectalis sling, wide aperture of the anal canal, evacuation of the
rectal contents, and good resistance of the pelvic floor. Yet these radiologic
signs appear to have lost their diagnostic value because healthy subjects and
patients with outlet obstruction or anal incontinence may present variations
in measurements of the anorectal angle, anal canal width, pelvic floor
movements, and residual volume after defecation
[2,3,4,5,6,7,8,9,10,11,12].
Moreover, any finding of changes in the morphology of the rectal wall is of
little diagnostic value because rectocele, mucosal prolapse, rectal
intussusception, and an absence of pelvic floor muscle relaxation are also
observed in asymptomatic subjects
[5,
8,
9,
13,14,15].
Another group of authors
[11] observed patterns
indicative of some degree of circumferential intussusception of the whole
thickness of the rectal wall in 50% of asymptomatic patients. This percentage
is higher than percentages reported by other groups of authors in patients
with evacuation disorders, the mean frequency of rectal intussusception being
27% (range, 3-31%)
[3,4,5,6,
8,
16,17,18,19,20,21]
and that of rectal prolapse being 12% (range, 2-16%)
[4,
5,
16,
17,
20,
21] in patients with
evacuation disorders. We therefore believe that the difficulty in
differentiating between defecographic findings in asymptomatic subjects with a
radiologic picture suggesting rectal intussusception and in symptomatic
patients with a radiologic diagnosis of rectal intussusception reflects a need
for more specific diagnostic criteria.
Therefore, the aim of this study was to provide measurements that would
allow a differential diagnosis to be made between findings for rectal
intussusception and prolapse and findings for normal folding in the rectal and
anal mucosa.
Materials and Methods
Our series consisted of 437 patients (115 males, 322 females; age range,
15-87 years; mean age, 49.5 years) with proctologic, micturitional, and
gynecologic symptoms who underwent a total of 471 dynamic evacuation
examinations: defecography was used for 130 examinations (27.6%),
colpodefecography for 19 (4%), and cystocolpodefecography for 322 (68.4%).
Repeated examinations in the same patient were not considered. A
retrospective analysis was thus made of 437 consecutive examinations.
Indications for radiologic examinations were defecation and micturition
disorders and, in women, gynecologic complaints. Because this was a control
study, defecography was performed in 43 asymptomatic subjects (17 men, 26
women; age range, 45-78 years; mean age, 58.7 years); because 23 of the women
had children (range, 1-3 normal deliveries), being nulliparous was not
considered an explanation for the absence of findings suggesting rectal
intussusception. All subjects gave their fully informed consent to take part
in the study, which was approved by the local bioethics committee.
All patients and control subjects underwent a complete clinical
examination, which included inspection, digital anorectal exploration, and
proctoscopy and, in the women, a digital vaginal exploration. Asymptomatic
subjects with previous pelvic and anorectal surgery with an incidental
clinical diagnosis of anorectal disease and who were of reproductive age were
excluded from the study. Defecography was refused by nine of the 52
individuals who were asked to enter the study.
Defecography
After the rectum was prepared using a disposable cleaning enema (Macrolax
Prontoclisma; AIC Carlo Erba, Milan, Italy), with the patient in the left
lateral decubitus position, the rectum was filled with 200 mL of a commercial
thick barium paste (Prontobario Esofago; Bracco, Milan, Italy) injected using
a soft diagnostic enema probe linked to a 60-mL plastic syringe. To opacify
the anal canal, paste injection was continued while the tip of the probe was
slowly withdrawn. In a few cases the vagina was also opacified with the same
commercial thick barium paste, but in most cases both the vagina and the
bladder were opacified with the commercial thick barium paste and a
water-soluble contrast medium, respectively. The patient was then asked to sit
in a vertical position on a radiolucent lavatory seat placed sideways on the
footplate of remote control fluororadiographic equipment. Four radiographs
(digital radiography has been available since 1997) in the right lateral
projection were made with the patient at rest, at voluntary maximum
contraction of the anal sphincter and pelvic floor muscles, during strain
without evacuation, and at maximum straining on completion of evacuation.
Fluoroscopy was recorded using a high-resolution S-VHS recorder (RTV 920
HIFI; Blaupunkt, Hildesheim, Germany) at rest, during coughing (to test fecal
stress incontinence), and throughout evacuation. A compensation cuneiform
acrylic filter with a maximum thickness of 5 cm was placed on the lower
surface of the collimator to attenuate the differences in radiolucency between
the pelvis and the areas of the anal canal, vagina, and urethra. Measurements
of the thickness and diameter of midline anatomic structures were corrected by
reference to a rectal probe with a known diameter.
Radiographic Analysis
Attention was focused on the radiologic diagnosis of rectal intussusception
and prolapse. After the forced evacuation, we measured, at the upper point of
invagination, the anterior folding thickness between the anterior
intussuscipiens edge and the anterior intussusceptum outline, the posterior
folding thickness between the posterior intussuscipiens edge and the posterior
intussusceptum outline, the intussuscipiens diameter between the anterior and
posterior intussuscipiens edges, and the intussusceptum lumen diameter between
the anterior and posterior intussusceptum outlines (Figs.
1A,1B
and
2A,2B).
A concomitant rectocele was excluded from the intussuscipiens diameter
measurement. The ratio between the intussuscipiens diameter and the
intussusceptum lumen diameter was also calculated.
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Fig. 1B. —Rectal intussusception in 47-year-old woman. Drawing shows
measurements of anterior rectal wall folding thickness (a), posterior rectal
wall folding thickness (b), intussuscipiens diameter (x), intussusceptum lumen
diameter (y), and vagina (v).
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Fig. 2B. —Rectal prolapse in 68-year-old woman. Drawing shows
measurements of anterior rectal wall folding thickness (a), posterior rectal
wall folding thickness (b), intussuscipiens diameter (x), intussusceptum lumen
diameter (y), and vagina (v).
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Statistical Analysis
All results were expressed as a mean value ± the standard deviation.
The Kruscal-Wallis one-way analysis of variance by ranks test was used to
compare groups. The p value was computed using the chi-square
approximation, with correction for ties; a p value of less than 0.01
was considered significant.
Results
On dynamic rectal examination a circumferential infolding of the rectal
wall was observed in 53 (12.1%) of 437 patients (16 men, 37 women; age range,
22-74 years; mean age, 53.7 years). In 35 (8%) of 437 patients, the folds
appeared to enter the rectal lumen at defecatory straining, extending downward
either gradually or abruptly and creating an annular filling defect in the
final image after forced evacuation. The folds were contained in the rectum in
14 (40%) of 35 patients and extended into the anal canal in 21 (60%) of 35
patients. Table 1 shows the
measurements for anterior and posterior rectal wall folding thickness, the
measurements for intusscipiens diameter and intussusceptum lumen diameter, and
the ratio. In these patients, a radiologic diagnosis of rectal intussusception
was made (Fig.
1A,1B).
In 18 (4.1%) of 437 patients, the folding protruded through the anal orifice
and was reduced spontaneously in eight (44.4%) of 18 patients and manually in
seven (38.9%) of 18; in three (16.7%) of 18 patients it could not be reduced.
In these patients, a radiologic diagnosis of rectal prolapse was made (Fig.
2A,2B).
Table 2 shows the relationship
between the predominant symptoms and the radiologic diagnoses of rectal
intussusception and prolapse. The most common symptoms of rectal
intussusception were fecal obstruction and pain, and of rectal prolapse were
tenesmus, fecal obstruction, and bleeding; only five of 53 patients had fecal
incontinence.
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TABLE 1 Defecographic Measurements in Patients with Rectal Intussusception (RI)
and Rectal Prolapse (RP) and in Asymptomatic Subjects (AS)
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Rectal outline changes mimicking intussusception were observed in 13 (30%)
of 43 asymptomatic subjects on completion of forced evacuation (Fig.
3A,3B).
Table 1 shows thickness
measurements of the rectal folding, thickness measurements of intussuscipiens
diameter and intussusceptum lumen diameter, and the ratio.
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Fig. 3B. —Rectal mucosal folds in asymptomatic 52-year-old man. Drawing
shows measurements of anterior rectal outline folding thickness (a), posterior
rectal outline folding thickness (b), intussuscipiens diameter (x), and
intussusceptum lumen diameter (y).
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Discussion
The significant clinical value of defecography in patients with anorectal
complaints has not yet been satisfactorily defined. An overlap exists between
some defecographic findings in asymptomatic and symptomatic subjects, and no
consensus has been reached on radiologic criteria for diagnosing rectal
intussusception and prolapse. Moreover, because the radiologic diagnosis of
rectal intussusception and prolapse is based on a subjective quantification of
the thickness of rectal folding, it is difficult to make a differential
diagnosis between rectal intussusception and mucosal folding on completion of
evacuation [7,
8,
20,21,22,23,24,25].
Some authors provide measurements for rectal folding thickness for patients
with rectal intussusception
[16,
26,
27], others provide
measurements for mucosal prolapse
[20], others for asymptomatic
subjects [11,
28] in the lateral projection,
and yet others [19] specify
measurements in the frontal projection. The different types of barium contrast
material used may influence the defecographic findings and may partly explain
the wide variation in the frequency of rectal folding reported in asymptomatic
subjects
[9,10,11,
13,14,15].
The use of commercial thick barium preparations is desirable because this
technical aspect should be standardized and barium pastes should no longer be
prepared by hand [15]. Lateral
projection is essential for rectal measurements with current defecographic
techniques, which include opacifying the vagina, the small intestine, and the
bladder [8,
16,
18,
20,
29], or the pouch of Douglas
[29]. Vaginal opacification
was performed with commercial thick barium paste; the use of a tampon soaked
in contrast material for opacifying the vagina was avoided because it may
hinder the identification of an enterocele
[18] and of any associated
rectal intussusception.
The appropriate assessment of dynamic abnormalities is crucial to the
defecographic diagnosis of rectal intussusception and prolapse, and motion
recording must be used routinely. Evacuative motion recording shows the
descent of a circumferential infolding of the rectal wall that enters the
rectal lumen or extends into the anal canal in rectal intussusception, or that
may protrude through the anal orifice in rectal prolapse.
In our study, in the same working conditions, we obtained and compared
measurements for the thickness of rectal folding in asymptomatic subjects and
in patients with rectal intussusception and prolapse. In our 437 consecutive
patients, rectal intussusception was found in 35 patients (8%) and rectal
prolapse in 18 (4.1%). The mean measurements for anterior and posterior rectal
wall folding thickness were significantly greater than those in asymptomatic
subjects with rectal outline changes mimicking rectal intussusception
(Table 1). Infolding in
intussusception is thicker than in other conditions because it consists of two
layers of the entire rectal wall and anteriorly may be broader; the infolding
may contain a peritoneocele, with or without an enterocele
[29].
The intussuscipiens diameter and intussusceptum lumen diameter were easily
measured because the intussuscipiens edges and intussusceptum outlines were
well recognizable, always being sharp in rectal intussusception and prolapse
(Figs.
1A,1B
and
2A,2B).
The mean intussuscipiens diameter measurement was greater and the mean
intussusceptum lumen diameter measurement was lower in rectal intussusception
and prolapse than in control subjects, these being linked to a thicker
infolding in rectal intussusception and prolapse that widens the
intussuscipiens and narrows the intussusceptum lumen. The mean value of the
ratio was thus significantly higher in rectal intussusception and prolapse
(Table 1). Moreover, the ratio
was useful because measurements of midline structures are not affected by
radiographic magnification, and different sizes of radiologic views
(radiographs, digital radiographs, spot films, video recordings) are
immediately comparable.
The ratio, with a cutoff of 2.5, is probably the most suitable tool for
distinguishing between patients with rectal intussusception and prolapse and
asymptomatic control subjects with rectal mucosal folding.
In conclusion, our radiologic method is similar to several current
defecographic techniques that include using commercial thick barium paste,
opacifying the vagina, putting the patient in a sitting position, and using
both static films and motion recording. Our findings show that no correlation
exists between predominant symptoms of patients and a radiologic diagnosis of
rectal intussusception or prolapse and that fecal incontinence is an uncommon
symptom; in rectal intussusception, rectal wall folding thickness and the
ratio are similar to those in rectal prolapse, because in rectal
intussusception and prolapse, invagination comprises two layers of the entire
rectal wall; and the rectal wall folding thickness and the ratio are
significantly greater in patients with rectal intussusception and prolapse
than in asymptomatic subjects with rectal mucosal folding. The defecographic
diagnosis of anorectal disorders and the consequent impact on patient
treatment may be enhanced by objective diagnostic criteria. The measurements
we used in diagnosing rectal intussusception and prolapse may be a step toward
achieving this goal.
Acknowledgments
We thank Sara Pearcey for correcting our English, C. Saccavini for his
advice on the statistical analysis, and E. Pagiaro for his help with the
database design.
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Abstract
Introduction
