Comparative Effectiveness of Imaging Modalities for the Diagnosis of Intestinal Obstruction in Neonates and Infants:: A Critically Appraised Topic.

RATIONALE AND OBJECTIVES: The purpose of this study was to critically appraise and compare the diagnostic performance of imaging modalities that are used for the diagnosis of upper and lower gastrointestinal (GI) tract obstruction in neonates and infants. METHODS: A focused clinical question was constructed and the literature was searched using the patient, intervention, comparison, outcome method comparing radiography, upper GI contrast study, and ultrasound in the detection of upper GI tract obstruction such as duodenal atresia and stenosis, jejunal and ileal atresia, and malrotation and volvulus. The same methods were used to compare radiography and contrast enema in the detection of lower GI tract obstruction such as meconium plug syndrome, meconium ileus, Hirschsprung disease, and imperforate anus. Retrieved articles were appraised and assigned a level of evidence based on the Oxford University Centre for Evidence-Based Medicine hierarchy of validity for diagnostic studies. RESULTS: There were no sensitivities/specificities available for the imaging diagnosis of duodenal atresia or stenosis, jejunal or ileal atresias, meconium plug, and meconium ileus or for the use of cross-table lateral radiography for the diagnosis of rectal pouch distance from skin in imperforate anus. The retrieved sensitivity for the detection of malrotation on upper GI contrast study is 96%, and the sensitivity for the diagnosis of midgut volvulus on upper GI contrast study is 79%. The retrieved sensitivity and specificity for the detection of malrotation with volvulus on ultrasound were 89% and 92%, respectively. The retrieved sensitivity and specificity for the detection of Hirschsprung disease on contrast enema were 70% and 83%, respectively. The retrieved sensitivity of invertogram for the diagnosis of rectal pouch distance from skin in imperforate anus is 27%. The retrieved sensitivities of perineal ultrasound and colostography for the diagnosis of rectal pouch distance from skin in imperforate anus were 86% and 100%, respectively. CONCLUSIONS: There is limited evidence for the imaging diagnosis of duodenal atresia and stenosis, jejunal and ileal atresias, meconium plug, meconium ileus, and imperforate anus, with recommended practice based mainly on low-quality evidence or expert opinion. The available evidence supports the use of upper GI contrast study for the diagnosis of malrotation and volvulus, with ultrasound as an adjunct to diagnosis. Contrast enema is useful in the investigation of suspected Hirschsprung disease, but a negative study does not outrule the condition. Colostography is the investigation of choice for the work-up of infants with complex anorectal malformations before definitive surgical repair.

Ultrasound-guided contrast enema for meconium obstruction in very low birth weight infants: Factors that affect treatment success.

INTRODUCTION: This study aimed to assess the therapeutic results of ultrasound (US)-guided water-soluble contrast enema in very low birth weight (VLBW) preterm infants (<1,500 g) with meconium obstruction and to study factors that affect therapeutic results. METHODS: This study included a total of 33 consecutive VLBW infants with clinically diagnosed meconium obstruction underwent US-guided water-soluble contrast enema, from April 2007 to March 2014. Patients were classified into two groups based on to procedure outcome: the success group (evacuation of the meconium plug resolution followed by improved bowel distention within 2 days of the procedure, without additional interventions), and the failure group (the contrast enema failed to relieve the obstruction, or other procedure-related complications occurred). Patient- and mother-related clinical factors and procedure-related factors were compared between both groups. RESULTS: Overall success rate was 54.5%, with 18 successful (M:F=10:8), and 15 failure (M:F=7:8) cases. When compared with the failure group, the success group patients showed statistically significant older gestational age (29(+1) vs. 27 weeks; p=0.028), larger birth weight (1023.1g vs. 790.3g; p=0.048), and higher body weight on the day of the procedure (1036.2g vs. 801.6g, p=0.049). However, no statistically significant differences were seen between other patient and maternal factors. Among the procedure-related factors, retrial of contrast injection during the procedure was associated with significantly higher success than the single trial (p=0.027). The presence of refluxed contrast into the distal ileum was the statistically significant predictor for success of the procedure (p=0.038). There were three cases of bowel perforation (9.1% per person). CONCLUSION: US-guided water-soluble contrast enema in VLBW infants with meconium obstruction showed a 54.5% success rate and a 9.1% perforation rate per person. Among the procedure-related factors, retrial of contrast injection during the procedure and the presence of refluxed contrast into the distal ileum were related to the success of the procedure.

Diminishing role of contrast enema in simple meconium ileus.

PURPOSE: Contrast enema is the initial study of choice for simple meconium ileus to confirm diagnosis and to relieve obstruction. Despite favorable historically published results, our clinical impression suggests decreased effectiveness of the contrast enema resulting in more surgical interventions in contemporary practice. METHODS: A retrospective multiinstitutional review for a 12-year period was conducted for neonates diagnosed with meconium ileus by contrast enema. The neonates were divided into 2 groups-historic group (HG = before 2002) and contemporary group (CG = after 2002). T test was used for comparison of continuous variables and chi(2) for categorical data. RESULTS: Thirty-seven total patients were identified (21 females and 16 males). Obstruction was relieved in 8 neonates (22% overall success rate). Average enema attempt per patient was decreased in the CG group compared to HG (1.4 vs 1.9). The success rate in the CG group was 5.5% (1/18) compared to 39% (7/18) in HG. CONCLUSIONS: In this review, success of contrast enema for relief of meconium ileus has significantly decreased over time. These findings may be because of reluctance to repeat enemas, change in radiologist experience, or use of contrast agent. As a result, higher rates of operative intervention are now observed. In stable patients, surgeons should recommend repeat enemas before exploration.

Contrast enema depiction of small-bowel volvulus in complicated neonatal bowel obstruction.

About one-half of patients with meconium ileus (MI) present with a complication such as volvulus, atresia, meconium peritonitis or giant cystic meconium peritonitis. The treatment of these complications requires surgery. However, the preoperative diagnosis of complicated MI is difficult. We describe two neonates with complicated small-bowel obstruction, one with MI related to cystic fibrosis and the other not related to cystic fibrosis. In both, contrast enema depicted a spiral appearance of the distal small bowel, which at surgery proved to be the result of volvulus associated with antenatal bowel perforation. This appearance of the small bowel on contrast enema in this clinical setting has not been previously described. The recognition of this spiral appearance of the distal small bowel suggests the need for surgery.

Neonatal ultrasonography to distinguish between meconium ileus and ileal atresia.

Meconium ileus can be difficult to distinguish from ileal atresia on plain radiographs and on contrast enema. Both show a microcolon in the face of a small bowel obstruction. The treatment of the two is very different. Meconium ileus obstruction may be relieved medically by contrast enema; ileal atresia requires prompt surgical intervention. This study was made to determine if abdominal ultrasonography might be helpful in distinguishing between these two entities. Abdominal ultrasonograms from the past 10 years of all patients with these two diseases who were studied with preoperative ultrasonography at Arkansas Children's Hospital were reviewed. Six of 16 patients with meconium ileus had preoperative ultrasonograms. All six patients with meconium ileus had multiple loops of bowel filled with very echogenic thick meconium. Four of 22 patients with ileal atresia had preoperative ultrasonograms. These four patients with ileal atresia had dilated loops of bowel filled with fluid and air. None had a dilated bowel filled with thick echogenic contents. Preoperative abdominal ultrasonography is proposed as a simple method for distinguishing between these two disease entities with very different treatment plans.