Discussion
In this study, we aimed to measure the adequacy of the SRB method
applied to take the rectal biopsy sample, which is the gold standard
diagnostic method for HD diagnosis, and in addition to report the
results of the test. We found that the SRB results obtained for HD were
sufficient for diagnosis. 62.5% of samples receiving SRB were
sufficient, and 37.5% of samples were insufficient or suspicious.
Insufficient sampling rates have been reported at different rates in
several studies in the literature. Although debates on this issue
continue, studies reported insufficient sampling rates at the range
between 11-50% (16-22). The main difference between these studies is
the design of the biopsy procedure that has taken with different
procedures. When we investigate the studies in the literature, we
observed that most of the studies have low insufficient material rate, 3
or 4 samples were taken in each biopsy procedure, and also biopsy was
repeated if the submucosal tissue was small. Mostly, studies reported
that 1-4 samples must be taken for each biopsy procedure. In many
studies, at least three samples were taken (17-22). Although we took two
samples from each patient in our study, we consider that our
insufficient sampling rate was acceptable. However, we considered that
the reason why this rate was higher when compared to other studies in
the literature was that we only obtained two samples in each procedure,
did not have SRB for the second time, and that we have just started to
apply this protocol in our clinic. In addition, the biopsy of our two
patients who were reported suspicious but considered insufficient may
have increased this rate.
In our study, when samples containing sufficient tissue and insufficient
samples were examined to confirm or exclude the disease in the
pathological examinations of biopsies; the average volume of sufficient
samples was 8.4 mm3 and 4.7 mm3 for
insufficient samples. Although these values are not statistically
significant, it is noteworthy that the volume of sufficient samples is
high. There are limited studies in the literature regarding the volume
measurement of samples. In the study of Muise, the average volume
obtained from SRB samples was reported as 14.8±7.8 mm3 (14). Several
studies reported that an adequate biopsy sample should be at least 3.5
mm in diameter (17, 23, 24). The increase in the volume of the samples
contributes to make a decision of diagnosis, but the depth of the biopsy
also is another important criterion for the diagnosis. In the
histopathological examinations of the samples in our study, the average
percentage of submucosal tissue of sufficient samples was found to be
52%, and the average of the insufficient samples was 40%. The
difference was statistically significant (p=0.033). Although there are
few prospective studies in this direction in the literature, it is
remarkable that retrospective studies reported that the rate of
submucosa in the biopsy tissue should not be less than 35-50% among the
inclusion criteria for the samples (14, 16, 17). In our study, similar
rates were reported with these studies in the literature in terms of
both the volume of SRB samples and the percentage of submucosal tissue.
In our study, we found that 73.3% of the biopsy tissues obtained from
the newborn age group were sufficient for histopathological examination,
while 44.4% of the patients aged between one month and three years were
considered sufficient. Although this difference is not statistically
significant, tissue adequacy in SRB was found to be higher in newborns
than in older babies in our study. When the studies in the literature
are examined, different results draw attention when the diagnostic
feature of SRB according to age groups is evaluated. While some studies
reported that there was no difference in the diagnostic yield of SRB
between age groups, several studies reported that insufficiency rate was
higher in infants younger than 1.5 months compared to infants older than
1.5 months (5, 22). In another study, it was reported that the tissue
adequacy rate was higher in babies older than one year compared to
babies older than one year old (25). In some studies, it has been
reported that the tissue adequacy ratio of SRB decreases after the age
of 3 (20, 26, 27). Since different results have been reported in the
literature on this issue, there is no consensus yet. Because in older
children, obtaining biopsy under sedation and the presence of
hypertrophic nerve fibres in the pathological evaluation of the tissue
obtained is a positive factor in diagnosis, previous enterocolitis
attacks and thicker intestinal mucosa could be considered as a negative
factor and may play a role in obtaining different results in each study.
Although the immaturity of the ganglion cells in the neonatal period and
the lack of hypertrophic nerve fibres are factors that challenge the
pathologist, an experienced pathologist can make a definitive diagnosis
with a sample that has reached a sufficient amount of submucosal tissue.
It is well-known that full-thickness rectal biopsy procedure is more
difficult, especially in the newborn period compared to older ages. In
our study, a higher material adequacy rate in newborn period could be
achieved with the SRB method, and lower complication rates were observed
in all-aged patients. These results show that the SRB technique is an
easily applicable and safe method in newborn periods.
In patients with a pre-diagnosis of HD, often anal dilatation and rectal
irrigation are recommended methods in terms of both diagnosis and
treatment during the decision of biopsy procedure (4). We planned a
prospective study by eliminating this suspicious procedure for the first
time in the literature, with the suspicion that both procedures may have
an oedema-forming effect on the rectum wall and may prevent sufficient
submucosal tissue obtain during the SRB procedure. We concluded that our
insufficient material rates were parallel to similar studies in the
literature. As a result, we revealed that giving patients a 48-hour
period without anal intervention before SRB does not provide any
benefit, and it is possible to perform biopsy whenever desired. When 9
of the biopsies obtained from 24 patients included in the study, which
were considered as insufficient material, were not included in the
evaluation, the specificity and sensitivity of SRB from 15 patients was
found to be 100%. It has been reported that the sensitivity of SRB in
the diagnosis of HD is 88-93% and its specificity is 95-99% (22, 23,
28-30). In the study of Nicole, no false negative or false positive
results were reported, similar to our study (28).
The limitations of our study were; when compared to previous studies,
the reason why our study was 100% accurate, and there was no margin of
error caused by the low number of cases. However, we consider that
excluding suspicious SRB results from the evaluation and working with an
experienced pathologist for the diagnosis of HD increased the accuracy
of the study results. Further prospective-randomized double-blind
studies including large-patient population, it may be expected that the
sensitivity and specificity rate, which is 100%, will decrease
slightly. Therefore, this high rate supports the opinions that the SRB
technique should be preferred over FTRB.