Colon transit scintigraphy: high impact on clinical decision making in severely constipated children

Objectives: Colon transit scintigraphy allows a physiologic and semi-quantitative assessment of motility disorders in the lower gastrointestinal tract. At our university hospital this technique has gained the preference over the more widespread pellet study in the diagnostic work-up of severely constipated children. The objective of this study was to evaluate the diagnostic yield and the impact on clinical decision making of colon transit scintigraphy in children with severe chronic functional constipation.

Methods: From September 2014 to October 2018, 36 patients (mean age 8.5 ± 4.9 years, range 2-17 years, 21 girls and 15 boys) with chronic, treatment-resistant functional constipation received an ¹¹¹In-DTPA colon transit scintigraphy. The scintigraphy was performed as part of the diagnostic work-up, with the aim of providing information on small bowel transit and segmental colonic transit. After an overnight fast, patients ingested a 7.5 - 15 MBq (age adapted) ¹¹¹In-DTPA water solution. Five pertechnetate (^99mTcO₄^-) position markers were placed on anatomic landmarks to create a reference frame. Sequential supine anterior/posterior planar imaging on an E.CAM SPECT-camera (Siemens, Germany) was performed up to 96 h (standard time points 4, 24, 48, 72, 96 h) post-ingestion, with a 4 minute scan duration. Image processing was performed on a Hermes system (Nuclear Diagnostics, Sweden) and geometric centers (GC) were calculated according to the SNMMI and EANM practice guideline for colon transit¹, with GC normal values between 3.0 and 4.8 at 48 hours post-ingestion.

Results: Patterns of colon transit were compared to those of the SNMMI and EANM practice guideline¹. Colon scintigraphy showed a normal transit time in 17 patients (47%) (mean GC at 48 h: 4.0 ± 0.7, range 3.0-5.0), delay in the distal colon in 5 patients (14%) (mean GC at 48 h: 3.9 ± 0.3, range 3.5-4.3), and colonic inertia in 14 patients (39%) (mean GC at 48 h: 2.4 ± 0.9, range 1.2-3.9). The difference between the first two groups was made based on the transit pattern and the findings at 72 h. The figure below shows an image example of each of these groups. In 29 patients (80%), the scintigraphic results did not correspond with the tentative clinical diagnosis, based on clinical examination, anorectal manometry and abdominal X-rays: in 16 patients the colon transit pattern was normal, in 5 patients the suspected site of dysmotility was altered, in 4 others it was broadened and in the last 4 it was narrowed. The results of the scintigraphy had therapeutic consequences for 20 patients (55%): in 12 (60%) the pharmaceutical treatment could be optimized (in most cases prucalopride, a serotonin type 4 receptor agonist, was added). In 2 other cases (10%) an enema was started. In 1 patient (5%), a loop sigmoidostomy was constructed, with a good effect on the chronic constipation. In 3 patients (15%) the planned surgical intervention was altered and in 2 patients (10%) an operation could be avoided.

Conclusions: This study shows the important value of colon transit scintigraphy in the investigation of functional constipation in children and the high impact on clinical decision making. Scintigraphic transit studies provide a noninvasive and safe assessment of whole-colon and regional colonic transit. Because the study depicts and quantifies the physiological transit mechanism, we were able to offer diagnostic differentiation for 80% of the patients and therapeutic alterations in 55% of the cases. To our knowledge, this is the largest study that investigates the clinical impact of colon transit scintigraphy in children and is in agreement with reported results in adult patients^2,3.

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