Operative intervention would be considered for SBO caused by phytobezoar, which is a trapped mass of undigested food leading to mechanical intestinal obstruction with higher risk of bowel strangulation 1. On the contrary, a non-operative approach could be effective for treating a series of SBFS-positive SBO without phytobezoar which develops secondary to increased water absorption and delayed transit 10. Inappropriate or delayed diagnosis of phytobezoar-related SBO may result in bowel bleeding, perforation, or fistula formation, which will threat patients’ life, bring about longer hospital stays and increased cost. Therefore, a more effective diagnostic methodology needs to be established to differentiate phytobezoar effectively from feces in childhood SBO. In the present study, we developed a combined diagnostic approach based on qCT + ASSS, which can improve the diagnostic performance to identify phytobezoar-caused SBO, one kind of SBFS-positive SBO need to be removed by surgery.
The advent of CT allows surgeons to find visible details, assisting clinical decision making in the management of phytobezoar-related SBO 3, 4, 6, 11. Early imageological differentiation between phytobezoar and feces was based on morphological characteristics, such as small-bowel feces sign (SBFS) 5, the presence of an encapsulating wall in the case of phytobezoar 3, or more tubular shape in the case of feces 4. However, the diagnostic performance of morphological findings from CT was greatly affected by variability between observers. Study of quantitative CT, including measurement of food debris length and mean attenuation may improve diagnostic performance in differentiating phytobezoar from feces 6. Our study showed that further analysis in children with SBFS-positive SBO is essential for differentiating phytobezoar from feces. Quantitative CT analysis turned out to be helpful in finding radiological differences of childhood phytobezoar and feces. Children with quantitative CT features such as shorter debris maximal length and stronger attenuation are more likely to have phytobezoar-related SBO. Stronger debris attenuation accompanied by presentation of complete bowel obstruction indicates irreversible obstruction occurring in phytobezoar-related SBO.
Although quantitative CT resolution has helped surgeons discriminate phytobezoar from feces in SBO, differential diagnosis of SBO in children is still challenging. On the one hand, single quantitative image-based analysis is not efficient. Our study shows that only debris attenuation has predictive value and, meanwhile, with the cut-off value of the debris attenuation (> 9 HU), the lower PPV (68% (13/19)) and NPV (65% (13/20)) indicate a potentially unrecognized phytobezoar and missed diagnosis. On the other hand, acute SBO is progressive, and variates determined by quantitative CT justly reflect anatomic changes of the SBO, which is one aspect of disease development. Clinical features, patients’ pathophysiological responses to SBO caused by different etiological factors, are also critical for judgment. In fact, increased studies in adults have elucidated the preferable performance of a treatment algorithm for SBO based on patients’ CT findings and clinical features 8, 12, 13. However, these effective clinical guidelines validated in adult studies cannot be applied to childhood SBO because of different causes and various clinical features in two different patient populations. A diagnostic method integrating quantitative CT analysis and clinical features for children with SBO is therefore greatly needed. In the present study, frequent vomiting, progressive abdominal distension, as well as increased white blood cells were more commonly observed in the phytobezoar group. It shows that clinical features could be practical for identify phytobezoar-related SBO in SBFS-positive SBO. In addition, with the advantage of consecutive evaluation, clinical features can reflect the progression of childhood SBO in a timely way. Therefore, the establishment of a more effective diagnostic method of differentiating phytobezoar from feces in SBO should incorporate existing quantitative CT findings in patients’ clinical features.
The AGESS-SBO scoring system, a systematic tool consisting of anatomic, physiological, and comorbidity parameters 7, is a relatively practical and comprehensive system that integrates CT findings and clinical features in the management of SBO. Based on quantitative CT findings, we developed a combined method that integrates quantitative CT analysis and the AGESS-SBO scoring system to differentiate phytobezoar from feces in childhood SBO. The criteria for evaluating anatomic parameters in the AGESS-SBO system relied on findings from enhanced CT performed with the use of contrast materials and higher radiation dose to recognize potential bowel ischemia. We noticed that few children with phytobezoar had undergone bowel strangulation in the early stage of hospitalization. Therefore, the prioritized purpose of CT in clinical decision making concerning phytobezoar-related SBO is to obtain imaging features of debris rather than to discover potential bowel ischemia. In fact, the signs obtained from physical examination are workable to identify potential bowel strangulation. Moreover, radiation damage to children, including the risk of radiation-induced cancer 14, 15 should be considered when enhanced CT is applied. The comorbidity index, which assessed the relationship between perioperative complications and age-related diseases such as diabetes and hypertension 16, was limited by the sample size in this study. Appropriate modifications of the AGESS-SBO scoring system could be more suitable for management of childhood SBFS-positive SBO.
Assessment of results showed that the higher AGESS-SBO scores presented in the phytobezoar group were correlated with higher degree of obstruction and development of SIRS. In fact, phytobezoar-related SBO in children was more likely associated with dramatic anatomic and physiological changes 17. However, SBFS-positive CT findings can appear in patients without SBO 18, 19. Increased PPV (80% (12/15)) and NPV (84% (16/19)) by the use of qCT + ASSS we developed in the present study could potentially decrease missed diagnosis or misdiagnosis. Differentiation based on high-performance diagnostic methods is efficient and can further guide appropriate clinical decision making in the management of phytobezoar-related SBO.
There are some limitations in our study. First, our diagnostic assessment is limited by its retrospective design and small sample size. In addition, patients selected in control group had no abdominal operation history, which were to be comparable with the history of affected children with phytobezoar-related SBO. It might not reflect overall situation of SBFS-positive SBO. Ultimately, more SBO-related parameters could be considered in future studies to improve the differential diagnosis of pediatric SBO further.