Constipation is one of the most common reasons for referral to the pediatric gastroenterology department. Patients are evaluated according to their history and physical examination. Diseases such as encopresis, urinary incontinence, and recurrent urinary tract infections may accompany chronic constipation in children (2, 4). In current study, the rate of encopresis was found to be 17% in the constipation group, which is consistent with the literature (15). In another study conducted from Turkey, the coexistence of encopresis was reported at a rate of 51.7% in chronically constipated children (16). The lower incidence of encopresis in our study may be due to the increased awareness of families in Turkey about chronic constipation compared to previous years, with the treatment of children before encopresis having improved. Nephrologic problems such as urinary incontinence and recurrent urinary tract infections were also detected in our constipated patients, as stated in the literature (17).
In a study evaluating the clinical findings of chronically constipated children, the rate of fecal impaction was found as 59.9% and anal fissure as 7.2% (18). In another study, anal fissure was reported at a rate of 26.9% in constipated children (16). Thus, our data are similar to those of other studies carried out in Turkey (27.1%).
Prolonged fecal retention in constipated children causes megarectum development. Various techniques are used in the radiological evaluation of megarectum and constipation. Abdominal X-ray can show the stool mass in the colon, but it is insufficient to identify megarectum (14). The contrast enema technique is difficult to apply in children due to the radiation risk, the invasiveness of the procedure, and the aspect of fright for the child. Rectal impaction may be detected most accurately via digital rectal examination. However, many constipated children and their parents find this procedure unpleasant. There is therefore a need to find a noninvasive method as an alternative to digital rectal examination to determine normal rectum diameter in children, to define thresholds for megarectum, and to detect fecal retention. Recently, measurement of the rectal diameter via US was reported as a noninvasive diagnostic tool for childhood functional constipation. Di Pace et al. reported that pelvic ultrasound was a quick and child-friendly investigation that could be used to document the presence of megarectum (19).
Studies have shown that children with chronic constipation have larger rectal diameters than healthy children. In a study conducted with 82 healthy children and 95 children with chronic constipation, rectal crescent size was measured as 2.4 cm in healthy children and 3.4 cm in constipated children, and this was statistically significant. The researchers reported that they used a cut-off point of 3.0 cm for defining megarectum in children (14). In a study conducted in Turkey, the rectal diameter of constipated children was evaluated when the bladder was empty and full. It was concluded that it was more meaningful to evaluate the rectum diameter when the bladder was empty, and it was shown that the rectum wall thickness was higher in children with constipation (10). Therefore, we evaluated the US measurements of our patients after urination. In a study by Klijn et al., the mean diameter of the rectum was 4.9 cm in children with constipation and 2.1 cm in a control group (20). In a different study, rectum diameters were measured from three different areas: the symphysis pubis, under the ischial spine, and at the bladder neck. It was found that the symphysis pubis, ischial spine, and bladder neck measurements of children with fecal retention were significantly higher than those of children without fecal retention. To define fecal retention, the cut-off value for the rectal diameter measured at the symphysis was taken as 27 mm with high sensitivity and specificity (95.5% and 94.1%, respectively). These authors concluded that rectal diameter measurement at the symphysis pubis by US is useful for detecting fecal retention easily and accurately (7). In our study, rectal diameter measurement at the symphysis pubis level was found to be significantly higher in children with constipation with stool retention in groups II and III compared to the control group. Significantly higher values were obtained in rectal diameter measurements made from symphysis pubis and ischial spine levels in 73–144 months old children with fecal retention compared to the control group. This result is similar to other studies in the literature.
The measurement of rectal diameter by age was evaluated for the first time in a study from Poland. The patients were grouped as under 3 years old, 3–6 years old, 6–12 years old, and over 12 years old and were compared with control group subjects of the same ages. It was determined that the rectum diameter values of the constipated groups of all ages were significantly higher than those of the control groups and that the difference was most prominent in children under 3 years of age. As the patients got older, the difference between them was smaller, but still significant (12). In a different study by Doniger et al., a strong correlation was found between enlarged transrectal diameter and constipation (21). When rectal diameter was measured from the axial plane, it was found to be 31.72 ± 6.93 mm in a constipated patient group and 19.85 ± 4.37 mm in a control group (p: 0.001) (1). In these studies, the patient groups were not divided into subgroups according to the presence or absence of fecal retention. Since rectal diameter values are affected by defecation and fecal retention (9), the study groups were divided into subgroups according to the presence or absence of stool in the rectum. The detailed evaluation of the data in this way makes our study different from other similar works to date. In our study, we found that the rectum diameter values measured from the symphysis pubis, bladder neck, and ischial spine planes of the group aged 73–144 months with fecal retention positive groups were statistically significantly higher than the control groups. We also found that the symphysis pubis and bladder neck planes measurements of children aged 73–144 months with fecal retention negative groups were statistically significantly higher than the control group. The mean rectal diameter measurements of the constipated group with fecal retention positive or negative increased with age, and this finding was compatible with the literature (12). We also found that the mean rectal diameters of constipated children with fecal retention positive and negative groups were similar between group III and IV despite the increasing age. In another different study re-evaluated rectum diameters after constipation treatment and showed that measurements decreased after 4 weeks of polyethylene glycol treatment (22). However, we could not re-evaluate our patients’ rectum diameter measurements after constipation treatment.
Berger et al., reported that they could not show a relationship between the clinical findings of constipation such as constipation duration, fecal retention, and fecal incontinence and ultrasonographic rectal diameter measurement, contrary to the literature data (8). According to our results, we found that the anterior rectal wall thickness increased as the duration of constipation increased. Contrary to the data of our study, in another study, the rectum wall thickness measurement of the constipated group was found to be lower. In that study, the correlation between constipation duration and anterior rectum wall thickness was not investigated (1). In addition, the difference in the anterior rectum wall thickness compared to the control group in that study may be due to the different constipation durations of the children in the patient group. In our study, anterior rectum wall thickness was higher in the constipated group with fecal retention positive compared to the control group only in Group III, while it was statistically significantly higher in the constipated group with fecal retention negative in Group II, Group III, Group IV. The fact that the constipated patients’ anterior rectum wall thickness, which was measured when the rectum was empty, was statistically significantly higher than in non-constipated children suggests that it could be a useful measurement as a marker of chronic constipation.
This study is conducted in healthy children with constipation complaints in four different age groups; This is the first study in which rectal diameter and anterior rectal wall thickness measurements in different planes were evaluated in detail in groups with and without stool retention. In addition, the number of patients is higher than in other studies conducted on this subject so far, and it is an important study in terms of determining the mean rectal diameter measurements and mean anterior wall thickness values of children in certain age ranges.
Limitations:
The limitations of our study are that we could not give a cut-off value for rectum diameter and anterior wall thickness due to the low number of children in the subgroups of the study. The other limitation is that unable to re-evaluate the rectum diameters of constipated patients after treatment.
In conclusion; while investigating chronic constipation, measurement of rectal diameter and anterior wall thickness with US technique as a noninvasive method in children who do not want to have a digital rectal examination may be useful in the diagnosis of constipation.