Transition to ultrasound as the first-line imaging modality for midgut volvulus: keys to a successful roll-out

Emerging Techniques in Pediatric Ultrasound, with Emphasis on Infants

Ultrasound is an important modality to assess pediatric patients and uses continue to increase. In this review, several emerging applications of ultrasound in pediatric patients are detailed, focusing on diseases impacting infants, including necrotizing enterocolitis, malrotation with midgut volvulus, and liver lesion characterization.

Ultrasound for infantile midgut malrotation: Techniques, pearls, and pitfalls

Midgut malrotation with volvulus is a surgical emergency with potentially devastating outcomes which include short gut syndrome necessitating long-term parenteral nutrition, overwhelming sepsis, and death. The clinical presentation is most frequently with bilious vomiting in the first days-weeks of life, which is non-specific and common. Timely imaging investigation is therefore crucial to prevent delays to diagnosis and treatment and avoid unnecessary surgical exploration in infants with non-surgical bilious vomiting. Fluoroscopic upper gastrointestinal contrast series (UGI) has been the first-line imaging modality to investigate midgut malrotation at pediatric surgical centers worldwide. However, there is a growing body of evidence to indicate that ultrasound (US) has greater diagnostic accuracy than UGI in this context. Furthermore, US offers the benefits of accessibility, portability, lack of ionizing radiation, and the ability to identify alternative diagnoses, and is beginning to attract significant attention and consideration in the literature. Over the last 3 years, we have transitioned to an "US-first" pathway for the investigation of midgut malrotation in infants with bilious vomiting. This pictorial essay illustrates our comprehensive approach, describes unique troubleshooting techniques, and highlights the variably published pitfalls we have encountered with the aim of encouraging wider adoption.

Impact of Focused Abdominal Ultrasound Utilization on Outcomes for Children With Midgut Volvulus

BACKGROUND

Ultrasound (US) is gaining acceptance for the evaluation of midgut volvulus in children. However, its impact on clinical outcomes is unknown. We aim to determine whether using US as a first-line modality changes imaging mobilization, time to surgery and re-feeding, length of stay, and frequency of bowel necrosis, short bowel syndrome, and death.

METHODS

An IRB-approved retrospective cohort study was performed at a tertiary pediatric institution. Eighty children with surgically confirmed midgut volvulus from 2014 to 2021 were compared before and after implementation of US as first-line imaging and based on the modality used to diagnose midgut volvulus.

RESULTS

Outcomes were not statistically different pre- versus post-implementation. Compared with patients who had UGI only, those who had US only or both had significantly quicker imaging mobilization (median: -33 min; 95% CI: -61.2, -4.8; p = 0.023 and median: -31 min; 95% CI: -58.5, -3.6; p = 0.028 respectively). Patients with US only were less likely to have bowel necrosis compared with those who had UGI only (9.1% versus 43.8%, p = 0.042). Patients who had US only or both were less likely to develop short bowel syndrome compared to UGI only (4.8% US only, 0% both, 40% UGI only; p = 0.027 for US only, p = 0.005 for both).

CONCLUSIONS

No statistically significant change in outcomes was found after implementation of US as first-line imaging for midgut volvulus. However, patients diagnosed with US only or US in combination with UGI had quicker imaging mobilization and decreased frequency of bowel necrosis and short bowel syndrome. Findings suggest that US has potential to improve patient outcomes.

LEVEL OF EVIDENCE

III.

Ultrasound imaging of bowel obstruction in neonates

Bowel obstruction (BO) in children has a wide differential diagnosis, ranging from non-urgent conditions to surgical emergencies. Abdominal radiographs are most often used as the first imaging modality for the evaluation of obstruction. However, for some indications, ultrasound can be the primary imaging modality. Therefore, it is incumbent on radiologists to recognize the types of bowel obstruction that can be recognized with US. Key sonographic features of BO include differential dilation of bowel loops, bowel wall thickening, and free fluid. "Do Not Miss" findings that indicate need for emergent treatment include volvulus, pneumoperitoneum, and/or signs of ischemia (bowel wall thinning and/or absent perfusion). The aim of this pictorial essay is to provide guidance on the sonographic technique and findings that enable identification of BO on US. Examples of neonatal BO on US, including common and less frequently encountered etiologies, are illustrated in this pictorial essay.

The performance of ultrasound and upper gastrointestinal study in diagnosing malrotation in children, with or without volvulus

BACKGROUND

Rapid diagnosis is crucial for pediatric patients with midgut volvulus and malrotation to prevent serious complications. While the upper gastrointestinal study (UGIS) is the traditional method, the use of ultrasound (US) is gaining prominence.

OBJECTIVES

To assess the diagnostic sensitivity and specificity of US compared to UGIS for malrotation and midgut volvulus.

METHODS

A cross-sectional study was performed on 68 pediatric patients who underwent US and/or UGIS before surgery for suspected midgut volvulus or malrotation in Kuala Lumpur (PPUKM and HTA), referencing surgical outcomes as the gold standard.

RESULTS

US demonstrated a higher specificity (100%) than UGIS (83%) for diagnosing malrotation, with a slightly lower sensitivity (97% vs. 100%). For midgut volvulus, US surpassed UGIS in sensitivity (92.9% vs. 66.7%) while maintaining comparable specificity. The SMA/SMV criteria showed better sensitivity (91.1%) than the D3 assessment (78.9%) on US, though both had high specificity.

CONCLUSION

US is equivalent to UGIS for identifying malrotation and is more sensitive for detecting midgut volvulus, supporting its use as a primary diagnostic tool. The study advocates for combined US and UGIS when either yields inconclusive results, optimizing diagnostic precision for these conditions.

Intussusception reduction methods in daily practice-a survey by the European Society of Paediatric Radiology Abdominal Imaging Taskforce

BACKGROUND

Image-guided intussusception reduction has been practised internationally for many decades. The use of different modalities, delayed repeat attempts, and sedation/anaesthesia are unknown.

OBJECTIVE

To survey the practice of image-guided intussusception reduction.

MATERIALS AND METHODS

A 20-point questionnaire created by the European Society of Paediatric Radiology (ESPR) Abdominal Imaging Taskforce was distributed via the ESPR members' mailing list and shared on social media between 28 March and 1 May 2023.

RESULTS

There were 69 responses from 65 worldwide institutions, with a mean of 18 intussusception reductions performed per year: 55/69 (80%) from 52 European institutions and 14/69 (20%) from 13 institutions outside of Europe. European centres reported using 19/52 (37%) fluoroscopy, 18/52 (35%) ultrasound, and 15/52 (28%) a mixture of both, with 30/52 (58%) offering a delayed repeat at 15 min to 24 h. Non-European centres reported using 5/13 (39%) fluoroscopy, 6/13 ultrasound (46%), and 2/13 (15%) a mixture of both, with 9/13 (69%) offering a delayed repeat attempt. Sedation or analgesia was used in 35/52 (67%) of European and 2/13 (15%) non-European institutions.

CONCLUSION

There is wide variation in how image-guided intussusception reduction is performed, and in the use of sedation/anaesthesia.

Notable Clinical Differences Between Neonatal and Post-Neonatal Intestinal Malrotation: A Multicenter Review in Southern Japan

BACKGROUND

Most cases of intestinal malrotation appear in neonates with bilious vomiting due to midgut volvulus, whereas in cases that develop beyond infancy, the initial symptoms vary. This study investigated the clinical features of these two populations and identified issues that should be considered in daily practice.

METHODS

A retrospective chart review was conducted from January 1, 2010, to December 31, 2022. Data on patients with intestinal malrotation were collected in an anonymized fashion from five pediatric surgical hub facilities in the Southern Kyushu and Okinawa areas of Japan.

RESULTS

Of the 80 subjects, 57 (71.3%) were neonates (Group N) and 23 (28.7%) were infants and schoolchildren (Group I). The frequencies of initial symptoms, such as abdominal distention (Group N: 19.3% vs. Group I: 13.0%), bilious vomiting (59.6% vs. 43.5%), and hematochezia (8.8% vs. 21.7%), were not skewed by the age of onset (p = 0.535, 0.087, and 0.141, respectively). Midgut volvulus was significantly more frequent in Group N (71.9% [41/57] vs. 34.8% [8/23]; p = 0.005), while the degree of torsion was greater in group I (median 360° [interquartile range: 180-360°] vs. 450° [360-540°]; p = 0.029). Although the bowel resection rate was equivalent (7.0% [4/57] vs. 4.3% [1/23]; p = 1.000), half of the patients in Group N presented with 180° torsion. The neonatal intestine has been highlighted as being more susceptible to ischemia than that in older children.

CONCLUSIONS

The incidence of midgut volvulus is higher in neonates than in older children. Even relatively mild torsion can cause ischemic bowel changes during the neonatal period.

LEVEL OF EVIDENCE

LEVEL III.

Ultrasound as the first line investigation for midgut malrotation: a UK tertiary centre experience

AIM

To present the first 22-months experience of transitioning to an ultrasound-first pathway for suspected midgut malrotation.

MATERIALS AND METHODS

An "ultrasound-first" imaging pathway was initiated in October 2021. Twenty-two-months later, a search was undertaken of all <1-year-old patients with "bilious", "malrotation," or "volvulus" as the imaging indication. Reports and images from upper gastrointestinal fluoroscopy (UGI) and ultrasound were reviewed, and diagnoses and outcomes were documented.

RESULTS

The search yielded 101 eligible cases between October 2021 and July 2023. Of the patients, 63/101 (62%) had both ultrasound and UGI: 47/63 (75%) ultrasound first, 16/63 (25%) UGI first. Thirty-one per cent (31/101) had ultrasound only and 7/70 (10%) UGI only. The pathway diagnosed 7/8 (88%) infants with midgut malrotation with or without volvulus and one infant who had an inconclusive ultrasound examination with a suspected an internal hernia and who was found to have malrotation volvulus at surgery. Twenty-one infants who had confidently normal ultrasound examinations and who also had UGI all had a normal duodenojejunal flexure position. Ultrasound detected alternative pathology in eight children. Duodenal visualisation improved with time: 6/15 (40%) in the first 6 months to 23/34 (68%) after the first year.

CONCLUSION

The transition to ultrasound as the first diagnostic test for midgut malrotation can be done safely and effectively in a UK centre, which previously relied solely on UGI.

Factors associated with diagnostic ultrasound for midgut volvulus and relevance of the non-diagnostic examination

BACKGROUND

Few reports explore the frequency and factors associated with diagnostic ultrasound (US) for midgut volvulus.

OBJECTIVE

To evaluate predictive factors for diagnostic US for midgut volvulus and clinical outcomes of patients with non-diagnostic US.

MATERIALS AND METHODS

This retrospective study included infants imaged for midgut volvulus with US. Exams were rated as diagnostic (midgut volvulus present or absent) or non-diagnostic by a pediatric radiologist, and in cases of disagreement with the original report, an additional pediatric radiologist was the tie-breaker. For each exam, the following were recorded: age, weight, respiratory support, exam indication, sonographer experience, and gaseous dilated bowel loops on radiography. Logistic regression models with "stepwise" variable selection were used to investigate the association of diagnostic US for midgut volvulus with each of the independent variables.

RESULTS

One hundred nineteen patients were imaged. US was diagnostic in 74% (88/119) of patients. In subsets of patients presenting with bilious emesis or age <28 days, US was diagnostic in 92% (22/24) and 90% (53/59), respectively. Logistic regression suggested that symptom type (bilious vs other) was the best predictor of diagnostic US (type 3 P=0.02). Out of 26 patients with available radiographs, US was diagnostic in 92% (12/13) of patients without bowel dilation on radiographs compared to 62% (8/13) of patients with bowel dilation (P=0.16). Weight, respiratory support, and sonographer experience did not differ between groups. Two sick neonates, ages 2 days and 30 days, in whom the primary clinical concern was dropping hematocrit and sepsis, respectively, had non-diagnostic ultrasounds in the setting of bowel dilation on radiography. Both were found to have midgut volvulus at surgery and both expired.

CONCLUSION

US was most frequently diagnostic in patients with bilious emesis or age less than 28 days. Non-diagnostic US for midgut volvulus must prompt a predetermined follow-up strategy, such as an additional imaging study (e.g., upper GI series), particularly in a sick child, as non-diagnostic US may miss midgut volvulus.

Imaging Features of Neonatal Bowel Obstruction

Radiologic evaluation of neonatal bowel obstruction is challenging owing to the overlapping clinical features and imaging appearances of the most common differential diagnoses. The key to providing an appropriate differential diagnosis comes from a combination of the patient's gestational age, clinical features, and imaging findings. While assessment of radiographs can confirm bowel obstruction and indicate whether it is likely proximal or distal, additional findings at upper or lower gastrointestinal contrast study together with use of US are important in providing an appropriate differential diagnosis. The authors provide an in-depth assessment of the appearances of the most common differential diagnoses of proximal and distal neonatal bowel obstruction at abdominal radiography and upper and lower gastrointestinal contrast studies. These are divided into imaging patterns and their associated differential diagnoses on the basis of abdominal radiographic findings. These findings include esophageal atresia variants including the "single bubble," "double bubble," and "triple bubble" and distal bowel obstruction involving the small and large bowel. Entities discussed include esophageal atresia, hypertrophic pyloric stenosis, pyloric atresia, duodenal atresia, duodenal web, malrotation with midgut volvulus, jejunal atresia, ileal atresia, meconium ileus, segmental volvulus, internal hernia, colonic atresia, Hirschsprung disease, and functional immaturity of the large bowel. The authors include the advantages of abdominal US in this algorithm, particularly for hypertrophic pyloric stenosis, duodenal web, malrotation with midgut volvulus, and segmental volvulus. ©RSNA, 2023 Online supplemental material is available for this article. Quiz questions for this article are available through the Online Learning Center.

US for Evaluation of Acute Abdominal Conditions in Neonates

US is the imaging modality of choice for evaluation of a variety of abdominal conditions, and in recent years it has also become useful and promising as a bedside technique for assessment of acute abdominal conditions in neonates. Bedside US can help, complement, and sometimes replace radiographic or contrast-enhanced studies in critically ill and labile neonates who are difficult to transport to the fluoroscopy suite. Some of the features of bedside US can be applied as point-of-care US (POCUS) of the sick neonate. Some of the abdominal conditions in neonates that can be assessed and monitored with bedside US are necrotizing enterocolitis and its complications, malrotation with a midgut volvulus, segmental volvulus, meconium peritonitis, and complicated inguinal hernia. High-resolution US with the use of 15-MHz and higher-frequency probes allows characterization of the bowel anatomy and features of intestinal abnormalities in neonates in fine detail. Color Doppler US and microvascular imaging improve accuracy in the detection and characterization of bowel vascularity, which is important in the treatment and follow-up of patients with intestinal conditions. ^© RSNA, 2023 Quiz questions for this article are available through the Online Learning Center. The slide presentation from the RSNA Annual Meeting is available for this article.

Assessment of care timelines in intestinal malrotation with volvulus: A retrospective chart review

BACKGROUND

Patients with intestinal malrotation with volvulus (MWV) may suffer bowel ischemia, which can be correlated with the timing of surgical intervention. The purpose of this study was to identify and assess time-blocks in the care of patients from initial physician assessment (IPA) to surgical intervention to highlight potential opportunities for improvement.

METHODS

Retrospective chart review of patients with MWV presenting to McMaster Children's Hospital between January 1st, 2000 and December 31st, 2020 (n = 31). Demographic data and time-blocks of care were identified and analyzed (p < 0.05 considered significant). All times were reported as medians.

RESULTS

22 males (71%) and 9 females (29%) were identified; median age was 9.8 d. IPA to incision was 10.7hrs and surgical consult to incision was 3.4hrs. Time to incision for patients <1 y was not significantly different than those >1 y (10.5hrs vs 10.7hrs, p = 0.737). The use of ultrasound did not significantly affect time to incision (7.9hrs vs 12.0hrs, p = 0.128). For patients requiring resection or having pan-necrosis there was no significant difference in time from IPA (10.9hrs vs 10.5hrs, p = 0.238) or surgical consult to incision (4.0hrs vs 3.3hrs, p = 0.808).

CONCLUSION

Time from IPA to surgical consult and time from surgical consult to surgical intervention represented the largest proportions of time. Age, use of ultrasound, and need for resection or having pan-necrosis did not significantly affect the time to incision. This data may be used to inform opportunities for expediting the management of patients with MWV once they have presented to a physician.

LEVEL OF EVIDENCE

III.

Ultrasound for malrotation and volvulus - point

Upper gastrointestinal series is considered the gold standard imaging test to evaluate for malrotation and midgut volvulus. US has been explored for this purpose in recent years and has been shown to be a good alternative because of its relatively good accuracy, fast learning curve for sonographers and radiologists, as well as convenience for children, clinical staff and radiologists in the neonatal intensive care unit. In this article we describe our experience and review the evidence supporting the use of emergency US primarily to diagnose midgut volvulus as well as its use as a problem-solving tool for the diagnosis of malrotation. The examination technique, normal and abnormal findings are described, with emphasis on the whirlpool and superior mesenteric artery cutoff signs to diagnose midgut volvulus.

Sonographic diagnosis of malrotation: it's complicated - counterpoint

Focused abdominal sonography (US) has been suggested as a first-line modality for the diagnosis of malrotation and volvulus in newborns. In this paper, the author reviews the strengths and weaknesses of US in the diagnosis and exclusion of malrotation and volvulus. The author reviews published implementation programs for using US in both conditions and describes the anatomical variations that limit the utility of US depiction of a retromesenteric duodenum in the exclusion of malrotation.

Neonatal Gastrointestinal Emergencies: A Radiological Review

BACKGROUND

Abdominal emergencies in neonates require surgical management in almost all cases and complications may include bowel perforation, sepsis, shock, and even death. Radiological imaging has become a very important aid in the clinical setting as it shortens time to diagnosis.

OBJECTIVE

The objective of this review is to discuss the more prevalent neonatal gastrointestinal emergencies, review appropriate imaging options, and illustrate common radiological presentations of these entities.

CONCLUSION

Despite advancements in imaging techniques, it is important to keep in mind that neonates have a higher susceptibility to the adverse effects of ionizing radiation, and therefore radiography and ultrasonography remain the main diagnostic modalities for ruling out the diseases with the worst prognosis. Other modalities (fluoroscopy, computed tomography, and magnetic resonance imaging) may have limited use in very specific conditions. All providers in an emergency department should be familiar with the basic radiological findings that may indicate a gastrointestinal emergency, especially in health institutions that do not have 24-h radiologist coverage.

Ultrasound for Midgut Malrotation and Midgut Volvulus: AJR Expert Panel Narrative Review

Midgut volvulus in association with malrotation is a pediatric surgical emergency. Prompt and accurate diagnosis is necessary to avoid bowel ischemia and necrosis, thereby reducing morbidity and mortality. Historically, the upper gastrointestinal (UGI) series has been the preferred imaging modality for the evaluation of both midgut malrotation and volvulus, although use of ultrasound (US) is increasing. In this narrative review, we describe the findings of midgut malrotation and volvulus on US, including practical tips for acquisition and interpretation; discuss the advantages and challenges of both imaging modalities; and propose a path and safeguards for possible transition to the use of US as the first-line modality for diagnosis, based on our experience in imaging children with midgut malrotation and volvulus.

Diagnosis and management of intestinal rotational abnormalities with or without volvulus in the pediatric population

Intestinal malrotation is a congenital anomaly that can be associated with midgut volvulus, requiring an emergent operation in order to maintain blood supply to the compromised intestine. It results from an abnormal rotation of the intestines, leading to three types of malrotation. Non-rotation is complete failure of the intestines to rotate, while the most common configuration is associated with the cecum in the mid-upper abdomen, close to a malpositioned duodenal-jejunal (DJ) flexure. This configuration has a narrow mesentery that has a high risk of volvulus. The final form of malrotation is incomplete rotation, where the DJ flexure and cecum are malpositioned, but the mesentery is not narrowed. The benefits of performing a Ladd's procedure for these individuals is controversial. Workup for malrotation should be considered in all patients who present with abdominal pain/distention and bilious emesis. An upper gastrointestinal contrast study is 93-100% sensitive and will show a corkscrew appearance when a volvulus is present. While the basic tenets of the Ladd's procedure have not changed and include detorsion of a volvulus, adhesiolysis of Ladd's bands and broadening of the mesentery, how this is accomplished and in whom are controversial. Laparoscopic Ladd's is associated with shorter hospital stays but also has a higher incidence of recurrent volvulus compared to an open approach. Patients with heterotaxy syndrome also represent a controversial group with some studies showing no difference in post-operative complications despite a higher mortality due to underlying cardiac disease, while other studies show a low incidence of volvulus and question the need for Ladd's in those who are asymptomatic. This review highlights the major aspects of diagnosing and treating malrotation, including the pathophysiology, workup, surgical options and areas of controversy.

Ultrasound for the diagnosis of malrotation and volvulus in children and adolescents: a systematic review and meta-analysis

CONTEXT

Despite the advantages of ultrasound (US), upper gastrointestinal contrast series (UGI) remains the first-line diagnostic modality in the diagnosis of midgut malrotation and volvulus in children.

OBJECTIVE

Evaluate the diagnostic accuracy of US in the diagnosis of malrotation with or without volvulus in children and adolescents aged 0-21 years, compared with the reference standard (diagnosis by surgery, UGI, CT, MRI, and clinical follow-up individually or as a composite).

DATA SOURCES

We searched the electronic databases Ovid-MEDLINE, Embase, Scopus, CINAHL, and the Cochrane library in October 2019 and updated on 18 August 2020.

STUDY SELECTION

Studies evaluating the diagnostic performance of US for diagnosis of midgut malrotation with or without volvulus in children (0-21 years).

DATA EXTRACTION AND SYNTHESIS

The data were extracted independently by two authors and a bivariate model was used for synthesis.

RESULTS

Meta-analysis of 17 cohort or cross-sectional studies and 2257 participants estimated a summary sensitivity of 94% (95% CI 89% to 97%) and summary specificity of 100% (95% CI 97% to 100%) (moderate certainty evidence) for the use of US for the diagnosis of malrotation with or without midgut volvulus compared with the reference standard. Subgroup analysis and meta-regression revealed better diagnostic accuracy in malrotation not complicated by volvulus, in the neonatal population and enteric fluid administration before US.

CONCLUSIONS

Moderate certainty evidence suggests excellent diagnostic accuracy and coupled with the advantages, a strong case exists for the use of abdominal US as the first-line diagnostic test for suspected midgut malrotation with or without volvulus in children and adolescents.