Ultrasound in the diagnosis of idiopathic hypertrophic pyloric stenosis

The impact of high-frequency transducers on the sonographic measurements of the pyloric muscle thickness in infants

BACKGROUND

Ultrasound is the modality of choice for the diagnosis of hypertrophic pyloric stenosis (HPS). The evolution of high-frequency transducers in ultrasound has led to inconsistent ways of measuring the pylorus.

OBJECTIVE

To standardize the measurements and evaluate the appearance of the normal and hypertrophied pylorus with high-frequency transducers.

MATERIALS AND METHODS

We retrospectively analyzed abdominal ultrasounds of infants with suspected HPS from January 2019-December 2020. We classified the layers of the pylorus while assessing the stratified appearance. Two pediatric radiologists measured the muscle thickness of the pylorus independently by two methods for interrater agreement. Measurement (a) includes the muscularis propria and muscularis mucosa. Measurement (b) includes only the muscularis propria. We also evaluated the echogenicity of the muscularis propria. The interrater agreement, mean, range of the muscle thickness, and the diagnostic accuracy of the two sets of measurements were calculated.

RESULTS

We included 300 infants (114 F:186 M), 59 with HPS and 241 normal cases. There was a strong agreement between the readers assessed in the first 100 cases, and ICC was 0.99 (95% CI, 0.98-0.99). Measurement (a), median thickness is 2.4 mm in normal cases and 4.8 mm in HPS. Measurement (b), median thickness is 1.4 mm in normal cases and 4.0 mm in HPS. Measurement (a) has an accuracy of 89.7% (95% CI, 85.7-92.8%) with 98.3% sensitivity and 87.6% specificity. Measurement (b) has an accuracy of 98.0% (95% CI, 95.7-99.3%) with 89.8% sensitivity and 100.0% specificity. The pylorus stratification is preserved in all normal cases and 31/59 (52.5%) cases of HPS. There was complete/partial loss of stratification in 28/59 (47.5%) cases of HPS. In all HPS cases, the muscularis propria was echogenic.

CONCLUSION

Measuring the muscularis propria solely has a better diagnostic accuracy, decreasing the overlap of negative and positive cases. The loss of pyloric wall stratification and echogenic muscularis propria is only seen in HPS.

Vomiting, Pyloric Mass, and Point-of-Care Ultrasound: Diagnostic Test Accuracy for Hypertrophic Pyloric Stenosis-A Meta-Analysis

BACKGROUND

Hypertrophic pyloric stenosis is a common cause of nonbilious vomiting in infants younger than 6 months. Its history, physical examination, and point-of-care ultrasound (POCUS) have not been compared for their diagnostic test accuracy.

OBJECTIVE

The aim of this systematic review was to quantify and compare the diagnostic test accuracy of a history of vomiting, a pyloric mass on palpation, and POCUS.

METHODS

We performed three searches of the literature from 1977 to March 2022. We evaluated bias using the QUADAS-2 (Quality Assessment Tool for Diagnostic Accuracy-2) tool. We performed a bivariate analysis.

RESULTS

From 5369 citations, we identified 14 studies meeting our inclusion criteria. We quantified three diagnostic elements: POCUS, a pyloric mass on palpation, and vomiting. We identified five studies that analyzed POCUS, which included 329 patients. POCUS had a sensitivity of 97.7% (95% confidence interval (CI) 93.1-99.3%) and a specificity of 94.1% (95% CI 88.7-97.1%) for detecting pyloric stenosis. We identified six studies that analyzed the presence of a pyloric mass, which included 628 patients. The palpation of a pyloric mass had a sensitivity of 73.5% (95% CI 62.6-82.1%) and a specificity of 97.5% (95% CI 93.8-99.0%). We identified four studies that analyzed vomiting, which included 355 patients. Vomiting had a sensitivity of 91.3% (95% CI 82.1-96.0) and a specificity of 60.8% (95% CI 8.5-96.3). Both POCUS and palpation of a pyloric mass had a high positive likelihood ratio (LR+: 17 and 33, respectively). The LR+ for vomiting was 5.0.

CONCLUSIONS

Both POCUS and palpable mass had high specificity and positive LR, whereas vomiting provided the lowest diagnostic test measures.

"The Most Satisfactory Procedure in the Field of Pediatric Surgery": The History of Hypertrophic Pyloric Stenosis

This historical retrospective explores the history of hypertrophic pyloric stenosis from its initial observations to the first surgical approaches to modern understandings of pathogenesis. The important work of Hirschsprung, Fredet, and Ramstedt remains a foundational part of management for this complex condition.

Basic practices for gastrointestinal ultrasound

The standard diagnostic modalities for gastrointestinal (GI) diseases have long been endoscopy and barium enema. Recently, trans-sectional imaging modalities, such as computed tomography and magnetic resonance imaging, have become increasingly utilized in daily practice. In transabdominal ultrasonography (US), the bowel sometimes interferes with the observation of abdominal organs. Additionally, the thin intestinal walls and internal gas can make structures difficult to identify. However, under optimal US equipment settings, with identification of the sonoanatomy and knowledge of the US findings of GI diseases, US can be used effectively to diagnose GI disorders. Thus, the efficacy of GIUS has been gradually recognized, and GIUS guidelines have been published by the World Federation for Ultrasound in Medicine and Biology and the European Federation of Societies for Ultrasound in Medicine and Biology. Following a systematic scanning method according to the sonoanatomy and precisely estimating the layered wall structures by employing color Doppler make diagnosing disease and evaluating the degree of inflammation possible. This review describes current GIUS practices from an equipment perspective, a procedure for systematic scanning, typical findings of the normal GI tract, and 10 diagnostic items in an attempt to help medical practitioners effectively perform GIUS and promote the use of GIUS globally.

Diagnostic accuracy of palpation and ultrasonography for diagnosing infantile hypertrophic pyloric stenosis: a systematic review and meta-analysis

Objective:

Although infantile hypertrophic pyloric stenosis (IHPS) is a well-known disease, there is no systematic review regarding the optimal diagnostic strategy. We conducted a systematic review and meta-analysis to obtain diagnostic accuracy of all methods to diagnose IHPS.

Methods:

According to the Preferred Reported Items for Systematic Reviews and Meta-Analysis guidelines, we searched MEDLINE and Embase to identify studies reporting sensitivity and specificity of all methods used to diagnose IHPS. Inclusion criteria were infants with suspicion of/or diagnosed with IHPS who underwent pyloromyotomy or had clinical follow-up. A random-effects model was used to obtain pooled estimates of sensitivity, specificity and area under the receiver operating characteristic curve.

Results:

After screening 5364 studies, we included 43 studies with in total 6085 infants (n = 4241 IHPS; n = 1844 controls). The diagnostic sensitivity of palpation ranged from 10.0 to 93.4% and decreased over time. Different parameters for ultrasonography were found. Most used parameters were pyloric muscle thickness (PMT) ≥ 3 mm (pooled sensitivity 97.6% and specificity 98.8%), PMT ≥ 4 mm (pooled sensitivity 94.0% and specificity 98.0%) or a combination of PMT ≥ 4 mm and/or pyloric canal length ≥16 mm (pooled sensitivity 94.0% and specificity 91.7%). The AUC showed high diagnostic accuracy (0.997, 0.966 and 0.981 respectively), but large heterogeneity exists. Due to the large differences in cut-off values no meta-analysis could be conducted for pyloric canal length and pyloric diameter.

Conclusion:

Palpation has limited sensitivity in diagnosing IHPS. We showed that ultrasonography has highest diagnostic accuracy to diagnose IHPS and we advise to use PMT ≥ 3 mm as cut-off.

Advances in knowledge:

This is the first systematic review and meta-analysis on diagnosing IHPS, which summarizes the available literature and may be used as a guideline.

Gastric Ectopic Pyloric Opening with Gastric Ulcer: A Rare Case

The stomach temporarily stores food and secretes gastric juices to break down and digest food. The normal process is the movement of food digested from the stomach to the duodenum, with the pylorus as a passageway. This paper reports the case of a patient with an ectopic gastric pylorus who presented with gastrointestinal bleeding. A 62-year-old man complained of melena with mild dizziness and nausea. An endoscopic examination revealed a gastric ulcer, approximately 1 cm in diameter, and exposed blood vessels on the posterior wall of the upper body. No normal pyloric structure was observed in the distal antrum, and an opening leading to the duodenum was noted in the posterior wall of the upper body adjacent to the ulcer. This case presents a congenital pyloric ectopic opening in the upper body of the stomach, not in the distal antrum, suggesting a rare gastric morphological variation.

Evaluating the validity of ultrasound in diagnosing hypertrophic pyloric stenosis: a cross-sectional diagnostic accuracy study

BACKGROUND

Our aims were to evaluate the ultrasound scan (USS) criteria in diagnosing hypertrophic pyloric stenosis (HPS), determine the best diagnostic threshold values for pyloric muscle thickness (PMT) and pyloric canal length (PCL), and assess the accuracy of flow through the pylorus.

METHODS

All patients who underwent pyloromyotomy at our tertiary paediatric surgery centre between July 2013 and June 2019 were identified (Group 1). All patients undergoing an USS to investigate for a possible HPS and did not undergo pyloromyotomy were also identified (Group 2). Accuracy was determined by Youden's Index (J) with the highest J determining the ideal cut-off value.

RESULTS

Two hundred and eighty-four patients (142 patients in each group) were included in the analysis. Using only the last USS before surgery, PMT provided an area under the curve (AUC) of 0.987 (n = 275), and PCL an AUC of 0.977 (n = 267). Ideal threshold values were 3.0 mm for PMT (J = 0.92), and 14.5 mm for PCL (J = 0.87). Combining PMT ≥3.0 mm with a PCL ≥14.5 mm resulted in a sensitivity of 95% and specificity of 99% (J = 0.94). The absence of flow through the pylorus on dynamic USS provided a sensitivity of 99% and specificity of 91% (J = 0.91; n = 277).

CONCLUSION

Combining threshold values of 3.0 mm for PMT and 14.5 mm PCL provides the highest accuracy for diagnosing pyloric stenosis on an ultrasound scan. These combined values were more accurate than observing for the absence of flow through the pylorus.

Presentation and outcomes in hypertrophic pyloric stenosis: An 11-year review

AIM

To evaluate the trend in presentation and postoperative outcomes of infants with hypertrophic pyloric stenosis (HPS) over the last decade.

METHODS

This was a multicentre retrospective study in two tertiary paediatric centres between 2005 and 2015 inclusive. Participants included 626 infants who underwent a pyloromyotomy for HPS. We collected data on presentation features (age, weight, clinical signs, blood gas results, ultrasound findings) and postoperative outcomes (length of stay (LOS), complications, time to first postoperative feed).

RESULTS

No trend was identified during the study period with regards to age, weight, biochemical findings (pH, chloride, base excess) or pre-operative ultrasound measurements. There was a downtrend in the number of palpated tumours over time, with a mean of 36% of tumours clinically palpated. Pyloric wall thickness had a moderate association with LOS in patients admitted for >8 days (correlation = 0.4752) but had a weak negative association with shorter lengths of stay (≤8 day, correlation = -0.094). Overall, median time to first feed was 7.80 h and improved yearly during the study period (hazard ratio = 1.07).

CONCLUSIONS

Patients presenting with HPS are not being identified at an earlier age or with fewer biochemical derangements, in contrast to our initial perceptions. Subsequently, biochemical derangements can still play an important role in the diagnosis of HPS, and attention needs to be given to fluid management and electrolyte correction in all patients with HPS.

Gastric ectopic pyloric opening: an unusual case

Stomach is the most dilated part of the digestive tube. The shape of the stomach could vary frequently without any clinical symptoms. Abnormality of pylorus including double pylorus and congenital pyloric stenosis has been reported but pyloric ectopic opening has not been reported before. We found a rare case of pyloric ectopic opening in the stomach body with a "hammer" shape stomach in a 72-year-old man. The patient complained of upper left abdominal with no past medical history or surgery history. The double-contrast examination showed a "hammer" shape stomach, with the pylorus opening high at the lesser curvature and enlarged distal end of the stomach. The gastrointestinal endoscopy showed that the pyloric antrum was approximately 3 cm below the cardia with a round and poor functioning opening. No obvious abnormalities in the bulb and descending part of the duodenum were observed. A large ulcer with whitish exudate covering the base was found on the posterior wall. Histological examination of the ulcer showed broken mucosal glands with atypical hyperplasia and focal carcinogenesis. This case shows a probably congenital pyloric ectopic opening in the gastric body with a "hammer"-shaped stomach, adding a new gastric morphological variation.

Review of bedside surgeon-performed ultrasound in pediatric patients

PURPOSE

Pediatric surgeon performed bedside ultrasound (PSPBUS) is a targeted examination that is diagnostic or therapeutic. The aim of this paper is to review literature involving PSPBUS.

METHODS

PSPBUS practices reviewed in this paper include central venous catheter placement, physiologic assessment (volume status and echocardiography), hypertrophic pyloric stenosis diagnosis, appendicitis diagnosis, the Focused Assessment with Sonography for Trauma (FAST), thoracic evaluation, and soft tissue infection evaluation.

RESULTS

There are no standards for the practice of PSPBUS.

CONCLUSIONS

As the role of the pediatric surgeon continues to evolve, PSPBUS will influence practice patterns, disease diagnosis, and patient management.

TYPE OF STUDY

Review Article.

LEVEL OF EVIDENCE

Level III.

Imaging beyond ultrasonically-impenetrable objects

Ultrasound images are severely degraded by the presence of obstacles such as bones and air gaps along the beam path. This paper describes a method for imaging structures that are distal to obstacles that are otherwise impenetrable to ultrasound. The method uses an optically-inspired holographic algorithm to beam-shape the emitted ultrasound field in order to bypass the obstacle and place the beam focus beyond the obstruction. The resulting performance depends on the transducer aperture, the size and position of the obstacle, and the position of the target. Improvement compared to standard ultrasound imaging is significant for obstacles for which the width is larger than one fourth of the transducer aperture and the depth is within a few centimeters of the transducer. For such cases, the improvement in focal intensity at the location of the target reaches 30-fold, and the improvement in peak-to-side-lobe ratio reaches 3-fold. The method can be implemented in conventional ultrasound systems, and the entire process can be performed in real time. This method has applications in the fields of cancer detection, abdominal imaging, imaging of vertebral structure and ultrasound tomography. Here, its effectiveness is demonstrated using wire targets, tissue mimicking phantoms and an ex vivo biological sample.

Pediatric emergency medicine point-of-care ultrasound: summary of the evidence

The utility of point-of-care ultrasound is well supported by the medical literature. Consequently, pediatric emergency medicine providers have embraced this technology in everyday practice. Recently, the American Academy of Pediatrics published a policy statement endorsing the use of point-of-care ultrasound by pediatric emergency medicine providers.  To date, there is no standard guideline for the practice of point-of-care ultrasound for this specialty. This document serves as an initial step in the detailed "how to" and description of individual point-of-care ultrasound examinations.  Pediatric emergency medicine providers should refer to this paper as reference for published research, objectives for learners, and standardized reporting guidelines.

Abdominal ultrasonography of the pediatric gastrointestinal tract

Ultrasound is an invaluable imaging modality in the evaluation of pediatric gastrointestinal pathology; it can provide real-time evaluation of the bowel without the need for sedation or intravenous contrast. Recent improvements in ultrasound technique can be utilized to improve detection of bowel pathology in children: Higher resolution probes, color Doppler, harmonic and panoramic imaging are excellent tools in this setting. Graded compression and cine clips provide dynamic information and oral and intravenous contrast agents aid in detection of bowel wall pathology. Ultrasound of the bowel in children is typically a targeted exam; common indications include evaluation for appendicitis, pyloric stenosis and intussusception. Bowel abnormalities that are detected prenatally can be evaluated after birth with ultrasound. Likewise, acquired conditions such as bowel hematoma, bowel infections and hernias can be detected with ultrasound. Rare bowel neoplasms, vascular disorders and foreign bodies may first be detected with sonography, as well. At some centers, comprehensive exams of the gastrointestinal tract are performed on children with inflammatory bowel disease and celiac disease to evaluate for disease activity or to confirm the diagnosis. The goal of this article is to review up-to-date imaging techniques, normal sonographic anatomy, and characteristic sonographic features of common and uncommon disorders affecting the gastrointestinal tract in children.

Recent changes in the features of hypertrophic pyloric stenosis

BACKGROUND

Hypertrophic pyloric stenosis (HPS) is a rare cause of non-bilious vomiting in young infants; the condition requires surgical management. Diagnosis is based on clinical, laboratory, and radiological findings. In the present study, we evaluate recent changes in the features of HPS.

METHOD

We retrospectively reviewed the demographic, clinical, and laboratory data on 56 HPS patients who underwent pyloromyotomy between 1996 and 2015. Patients were divided into two groups according to date of operation (group 1, 1996-2006; group 2, 2007-2015).

RESULTS

Group 1 consisted of 30 patients and group 2, 26. The age at diagnosis was longer in group 2 (43.3 ± 13.1 days) than group 1 (37.4 ± 17.7 days). All diagnoses were confirmed on ultrasonography. Pyloromyotomy was performed on all 56 patients (48 boys, 8 girls). Significant between-group differences were evident in terms of age at onset of vomiting; rate of dehydration; development of palpable olive-shaped abdominal mass; serum urea and creatinine; acid-base status; and air distribution pattern on abdominal radiography (all P < 0.05).

CONCLUSION

The frequency of olive-shaped abdominal mass evident on physical examination decreased significantly over time, and was lower than published values. Early diagnosis triggers timely support and surgical intervention, and may thus prevent development of the classical clinical and laboratory findings of late-stage HPS. The remarkable recent advances in ultrasonography and techniques allow HPS to be diagnosed earlier than formerly.

Olive without a cause: the story of infantile hypertrophic pyloric stenosis

For many diseases and medical conditions the clinical recognition and the development of accurate diagnostic methods and the etiological cause precede effective treatment. In the case of infantile hypertrophic pyloric stenosis (HPS), this sequence of events did not happen. Clinical recognition of the entity proceeded directly to the development of curative treatment. Reliable diagnostic imaging methods followed, but a definitive etiology has not been elucidated. This paper reviews the historical aspects of hypertrophic pyloric stenosis, discusses how and why it took so long for this not uncommon disease to be recognized, and highlights the physicians who changed an often fatal disease into an easily diagnosed and treated minor affliction.

Evaluation of hypertrophic pyloric stenosis by pediatric emergency physician sonography

OBJECTIVES

The objective was to evaluate the accuracy of pediatric emergency physician (EP) sonography for infants with suspected hypertrophic pyloric stenosis (HPS).

METHODS

This was a prospective observational pilot study in an urban academic pediatric emergency department (PED). Patients were selected if the treating physician ordered an ultrasound (US) in the department of radiology for the evaluation of suspected HPS.

RESULTS

Sixty-seven patients were enrolled from August 2009 through April 2012. When identifying the pylorus, pediatric EPs correctly identified all 10 positive cases, with a sensitivity of 100% (95% confidence interval [CI] = 62% to 100%) and specificity of 100% (95% CI = 92% to 100%). There was no statistical difference between the measurements obtained by pediatric EPs and radiology staff for pyloric muscle width or length (p = 0.5 and p = 0.79, respectively).

CONCLUSIONS

Trained pediatric EPs can accurately assess the pylorus with US in the evaluation of HPS with good specificity.

Evaluation of ultrasonographic parameters in the diagnosis of pyloric stenosis relative to patient age and size

INTRODUCTION

Pyloric thickness of 3 mm or higher and length of 15 mm or higher by ultrasonography (US) is widely accepted as diagnostic criteria for pyloric stenosis (PS). However, infants presenting at earlier ages are held to this same criteria, which may not be applicable.

METHODS

Retrospective review was conducted on patients evaluated with pyloric US to rule out PS from May 2010 through December 2010. Pearson correlation was used to detect an association between weight and age with pyloric thickness and length. Sensitivity and specificity for US parameters were determined.

RESULTS

Three hundred four patients underwent 318 ultrasounds, of which 67 had PS. Of those with PS, age and weight had a positive correlation with thickness (P < .007), and age positively correlated with length (P < .001). In patients with and without PS, there was a negative correlation for both age and weight with thickness (P < .02). Those who did not have PS held a stronger negative correlation between age and thickness (P = .002). Overall, US had a 100% sensitivity and specificity for PS. Thickness of 3 mm or higher was 100% sensitive and 99% specific, and pyloric length of 15 mm or higher was 100% sensitive and 97% specific.

CONCLUSIONS

Although significant associations between age and weight with pyloric thickness and length may exist, our data indicate that this does not have an impact on the diagnostic criteria for PS.

Epidemiological features of infantile hypertrophic pyloric stenosis in Taiwanese children: a Nation-Wide Analysis of Cases during 1997-2007

Objective

To describe the epidemiological characteristics of infantile hypertrophic pyloric stenosis (IHPS) in ethnic Chinese children.

Materials and Methods

We reviewed the National Health Insurance claims database and analyzed data from children less than one year of age who had been diagnosed with IHPS (ICD-9-CM 750.5) and had undergone pyloromyotomy (ICD-9-CM 43.3). We analyzed the incidence, gender, age at diagnosis, length of hospital stay, seasonal variation and cost of IHPS from data collected between January 1997 and December 2007.

Results

A total of 1,077 infants met inclusion criteria, including 889 boys and 188 girls. The annual incidence of IHPS ranged from 0.30 to 0.47 per 1,000 live births with a mean incidence of 0.39 per 1,000 live births. Between 2002 and 2007, the incidence showed a declining trend (P = 0.025) with coincidentally increasing trends for both exclusive breastfeeding (P = 0.014) and breastfeeding plus bottle feeding (P = 0.004). The male-to-female rate ratio was dynamic and increased from 3.03 during the first two weeks of life to 8.94 during the 8^th through 10^thweeks of life. The overall male-to-female rate ratio was 4.30. The mean age at diagnosis was 43.1±2.4 days. After analyzing the months of birth and hospital admission, no seasonal variation associated with IHPS was detected. The mean length of hospital stay was 8.28±7.10 days.

Conclusions

The incidence of IHPS in Taiwan, a country with a majority ethnic Chinese population, was lower than observed incidences in Caucasian populations living in Western countries. Breastfeeding campaigns and low maternal smoking rates may contribute to the lower incidence of IHPS in Taiwan. However, additional studies with longer follow-up periods are needed.

Antenatal imaging: does the postnatal impact justify the effort?

This review explores what is already understood about antenatal diagnosis of a variety of conditions,including Down syndrome, what progress has been made in this field, the role that imaging plays in the diagnostic pathway and the impact on management of pregnancies and the parental decision process. An overview of future potential developments is also made.

The changing clinical presentation of hypertrophic pyloric stenosis: the experience of a large, tertiary care pediatric hospital

The authors reviewed the clinical and laboratory data from cases of hypertrophic pyloric stenosis (HPS) diagnosed at their institution from 2006 to 2008. They assessed and compared presentation of patients with HPS over time at their institution. A total of 118 patients were included in this study. An "olive" was palpated in only 13.6% of cases. This is in contrast to older studies, where more than 50% of the patients were reported to have a palpable "olive" depending on when the study was conducted. In patients from this institution, hypochloremia was present in 23% and alkalosis in 14.4%, which are less frequent than the incidence of these abnormalities in older studies. There was a change in the additional "classical" symptoms, represented by the lower percentage of infants in whom an "olive" was palpated and the lower numbers of patients with severe electrolyte imbalances. The reason for this change appears to be the frequent use of ultrasound.

Gastrointestinal tract imaging in children: current techniques

Imaging of the gastrointestinal (GI) tract in children continues to evolve, with new techniques, both radiological and non-radiological, being added to the repertoire. This article provides a summary of current imaging techniques of the GI tract (primarily the upper GI tract) and the relationship between those techniques. It covers the upper GI series and other contrast studies, US, CT and MRI. Note is also made of the contribution now made by capsule endoscopy (CE). Abdominal emergency imaging is not covered in this article.

Early pyloric stenosis: a case control study

OBJECTIVE

Pyloric stenosis (PS) is rare in the first 2 weeks of life, often leading to delays in diagnosis and treatment. We conducted a case control study to delineate the characteristics of patients with early PS (EPS). In addition, we tested the hypothesis that patients with EPS present with a smaller pylorus than older patients.

METHODS

A database of all patients presenting with PS to a children's hospital over a 5-year period (2002-2006) was obtained. Each patient admitted during the first 2 weeks of life (subject) was matched to a patient admitted after 4 weeks of age (control), with the same gender, electrolyte status, and treating surgeon. A single pediatric radiologist, blinded to patient age, reviewed all available ultrasounds retrospectively. Demographic, clinical, diagnostic, therapeutic, and outcome data were compared.

RESULTS

During the study period, 278 pyloromyotomies were performed for PS. Sixteen patients (5.8%) presented with EPS between 2 and 14 days of life. EPS patients had a higher prevalence of positive family history (31 vs. 0%, P = 0.043), and breast milk feeding (75 vs. 31%, P = 0.045). Sonographic measurements showed a pylorus that was of significantly less length (17.1 +/- 0.6 vs. 20.5 +/- 0.9 mm, P = 0.006) and muscle thickness (3.5 +/- 0.2 vs. 4.9 +/- 0.2 mm, P < 0.001) in patients with EPS. Hospital stay was significantly longer for EPS patients (4.3 +/- 0.9 vs. 2.0 +/- 0.1 days, P = 0.19).

CONCLUSIONS

Babies presenting with EPS are more likely to be breast fed and to have a positive family history. EPS is associated with a longer hospital stay. Use of sonographic diagnostic measurements specific to this age group may prevent delays in diagnosis and treatment, and improve outcomes.

Negative exploration for pyloric stenosis--is it preventable?

BACKGROUND

The diagnosis of infantile hypertrophic pyloric stenosis (IHPS), although traditionally clinical, is now increasingly dependent on radiological corroboration. The rate of negative exploration in IHPS has been reported as 4%. The purpose of our study was to look at elements of supportive clinical evidence leading to positive diagnosis, and to review these with respect to misdiagnosed cases undergoing negative exploration.

METHODS

All infants undergoing surgical exploration for IHPS between January 2000 and December 2004 were retrospectively analysed with regard to clinical symptoms, examination findings, investigations and operative findings.

RESULTS

During the study period, 343 explorations were performed with a presumptive diagnosis of IHPS. Of these, 205 infants (60%) had a positive test feed, 269 (78%) had a positive ultrasound scan and 175 (55%) were alkalotic (pH >or=7.45 and/or base excess >or=2.5). The positive predictive value for an ultrasound (US) diagnosis was 99.1% for canal length >or=14 mm, and 98.7% for muscle thickness >or=4 mm. Four infants (1.1%) underwent a negative surgical exploration; Ultrasound was positive in 3, and negative in 1(who underwent surgery on the basis of a positive upper GI contrast). One US reported as positive had a muscle thickness <4 mm. Two false positive US were performed at peripheral hospitals. One infant had a false positive test feed following a positive ultrasound diagnosis. Two infants had negative test feeds.

CONCLUSION

A 1% rate of negative exploration in IHPS compares favourably with other studies. However potential causes of error were identified in all 4 cases. Confident diagnosis comprises a combination of positive test feed and an 'in house US' in an alkalotic infant. UGI contrast study should not be used in isolation to diagnose IHPS. If the test feed is negative, strict diagnostic measurements should be observed on US and the pyloric 'tumour' palpated on table under anaesthetic before exploration.

Hypertrophic pyloric stenosis in newborns younger than 21 days: remodeling the path of surgical intervention

BACKGROUND

According to currently accepted diagnostic criteria, ultrasonography confirms hypertrophic pyloric stenosis (HPS) when the pyloric muscle thickness (MT) is greater than 4 mm and the pyloric channel length (CL) is greater than 15 mm. Hypertrophic pyloric stenosis frequently presents in newborns younger than 21 days; yet, the diagnostic criteria in this younger population remain poorly defined. We, therefore, sought to define the diagnostic criteria for HPS in newborns younger than 21 days.

METHODS

Ultrasonographic measures of pyloric MT and CL were obtained by retrospective chart review (2000-2006) at a single institution for all newborns (aged 10 days to 6 weeks) with an intraoperatively proven diagnosis of HPS. Demographic characteristics and ultrasonographic measurements were collected, and features differentiating younger (21 days or younger) from older newborns were assessed. Measures of pyloric MT and CL were analyzed in 7-day increments, and comparisons were made between newborns aged 21 days or less and newborns 22 to 42 days of age. Based upon these features, a set of ultrasonographic parameters to establish the diagnosis of HPS in younger patients was defined.

RESULTS

Three hundred fourteen newborns (83% male) underwent pyloromyotomy of whom 64% (n = 200) had a preoperative pyloric ultrasound. Sixty newborns (19%) were younger than 21 days, of whom 51 (85%) had preoperative ultrasonography. The ultrasound measurement of HPS was significantly decreased in younger vs older newborns: (MT, 3.7 +/- 0.65 vs 4.6 +/- 0.82 mm, P < .05; CL, 16.9 +/- 2.8 vs 18.2 +/- 3.4 mm, P < .05). Importantly, the mean ultrasound measurement for young newborns with HPS typically fell within the currently defined "normal" or "borderline" range. A linear relationship was determined to exist between pyloric MT and CL and patient age, suggesting the use of 3.5 mm as a "cutoff" in younger patients.

CONCLUSIONS

These findings suggest that current guidelines to diagnose HPS do not accurately diagnose HPS in children younger than 3 weeks, and these findings raise the need to evaluate the decision analysis algorithm using prospective studies.

Use of ultrasound in 187 infants with suspected infantile hypertrophic pyloric stenosis

The diagnostic efficacy of ultrasound (US) in the diagnosis of infantile hypertrophic pyloric stenosis (IHPS) was evaluated, with particular attention paid to whether prematurity, age or weight correlate significantly to the sonographic measurements. The medical records of 187 infants with suspected IHPS were reviewed retrospectively. Eighty-seven had an US examination with details of the pylorus. Fifty-nine of these gave a positive diagnosis. The US criteria for a positive diagnosis were pyloric muscle thickness (PMT)>or=3 mm and pyloric muscle length (PML)>or=17 mm. The mean overall PMT was 4.14 mm and mean overall PML was 18.99 mm. Premature infants had a lower mean PML (17.8 mm) than the term infants (PML mean 19.3 mm); however, this was not significant (t-value 1.92, P=0.062). The sensitivity and specificity of PMT was 91 and 85%, respectively, and of PML 76 and 85%, respectively. The ability of US to diagnose IHPS using our criteria was significant (t-value, PMT 14.93 and PML 6.89; P<0.0001). There was no significant correlation between age, weight or prematurity and a sonographic diagnosis of IHPS (Pearson's coefficient<0.3). Therefore, the same US criteria should apply irrespective of prematurity, age or weight. Borderline PMT and PML measurements necessitate repeat US or alternative imaging.

Pyloric stenosis

In 1717, Blair first described pyloric stenosis based on autopsy findings. It was not until 1887 that Hirschsprung described the clinical picture and pathology of pyloric stenosis. Ninety years later, Teele and Smith described the use of ultrasonography to diagnosis pyloric stenosis. Traditionally, this diagnosis has been based on the clinical findings of projectile nonbilious vomiting, the palpation of a pyloric tumour (or “olive”), and the presence of classic metabolic disturbances. Currently, ultrasonography is regarded as the diagnostic test of choice for an infant presenting with nonbilious emesis in which an “olive” is not palpated.

The Vomiting Neonate: A Review of the ACR Appropriateness Criteria and Ultrasound’s Role in the Workup of Such Patients

Ultrasound (US) plays a central role in the diagnostic imaging workup for infantile vomiting. This paper reviews the major causes of vomiting in the first months of life and the use of US and other modalities for their imaging assessment. The differential diagnostic possibilities are reviewed by examining 3 clinical scenarios of bilious vomiting during the first days of life, nonbilious vomiting since birth, and projectile vomiting first occurring after several weeks of life. These are the 3 scenarios that were used for the American College of Radiology (ACR) Appropriateness Criteria for Vomiting in Infants up to 3 Months of Age.

The sonographic double-track sign: not pathognomonic for hypertrophic pyloric stenosis; can be seen in pylorospasm

OBJECTIVE

The "double-track" sign has previously been reported as specific for hypertrophic pyloric stenosis when noted on an upper gastrointestinal series. The sign has been noted on sonographic examinations as well. We sought to determine whether this sign can also be seen in cases of pylorospasm diagnosed by sonography, proving it not to be pathognomonic for hypertrophic pyloric stenosis.

METHODS

The data obtained prospectively from 91 consecutive patients studied between 1999 and 2002 by sonography for projectile vomiting were retrospectively reviewed. Cases with diagnoses of hypertrophic pyloric stenosis or pylorospasm were reviewed for the imaging finding of the double-track sign.

RESULTS

Thirty-seven patients had a sonographic diagnosis of hypertrophic pyloric stenosis that was confirmed surgically. Twenty-six (70.2%) showed a sonographic double-track sign. Thirty-four patients had a sonographic diagnosis of pylorospasm that was confirmed by close clinical follow-up. Eighteen (52.9%) showed a sonographic double-track sign.

CONCLUSIONS

The sonographic double-track sign can be seen in cases of pylorospasm as well as hypertrophic pyloric stenosis. It is not pathognomonic for hypertrophic pyloric stenosis.

Infantile hypertrophic pyloric stenosis

Infantile hypertrophic pyloric stenosis is a common condition affecting young infants; despite its frequency, it has been recognized only for a little over a century, and its etiology remains unknown. Nevertheless, understanding of the condition and of effective treatment have undergone a remarkable evolution in the 20th century, reducing the mortality rate from over 50% to nearly 0%. The lesion is characterized by gastric outlet obstruction and multiple anatomic abnormalities of the pyloric antrum. The antropyloric muscle is abnormally thickened and innervated, and the intervening lumen is obstructed by crowded and redundant mucosa. Recognition of the obstructive role of the mucosa led to discovery of effective surgical treatment. Accurate clinical diagnosis in patients in whom a thickened antropyloric muscle is not readily palpable can be difficult, resulting in delayed diagnosis and can lead to emaciation and electrolyte imbalance, making the patient a suboptimal surgical candidate. Current imaging techniques, particularly sonography, are noninvasive and accurate for identification of infantile hypertrophic pyloric stenosis. Successful imaging requires understanding of anatomic changes that occur in patients with this condition and plays an integral role in patient care. Accurate, rapid, noninvasive imaging techniques facilitate rapid referral of vomiting infants and prompt surgical treatment of more suitable surgical candidates.

Does dehydration affect thickness of the pyloric muscle? An experimental study

Congenital hypertrophic pyloric stenosis (CHPS) is a common condition in infancy associated with smooth muscle hypertrophy and resulting in pyloric outlet obstruction. The final diagnosis of CHPS is based on precise ultrasonographic measurements of length and width of the pyloric muscle. Based on our clinical and sonographic experience, we observed that smaller measurements of the pyloric muscle were obtained in dehydrated infants than in children examined after proper fluid restoration. The clinical importance of these observations was evident because false-negative results could be obtained. An experimental animal work followed, proving our clinical observation to be true. A significant difference of about 30% to 50% was found between measurements of the muscle thickness of the gastric and pyloric muscles in a state of water deprivation, as compared with a state of full hydration (p < 0.05). Based on our preliminary results, we suggest that children with suspected CHPS should be well hydrated before the ultrasound (US) examination is performed, to avoid false-negative results and a consequent delay in treatment.

Ultrasound diagnosis of infantile hypertrophic pyloric stenosis: determinants of pyloric length and the effect of prematurity

AIM

To evaluate the determinants of sonographic measurements of pyloric length and muscle thickness in infants with hypertrophic pyloric stenosis (HPS) and to determine whether infants born prematurely have proportionately smaller measurements.

MATERIALS AND METHODS

A retrospective review was carried out of 190 infants operated on for HPS at Bristol Children's Hospital over a 5-year period. Sonographic measurements of pyloric length and muscle thickness were related to age, history of prematurity, weight, sex and family history of HPS.

RESULTS

Pyloric length in infants with HPS was significantly greater in those born at term compared to those born prematurely (18.6 mm [SD 2.2] vs 17.3 mm [SD 3.1], P = 0.043); this was explainable by body weight, with length increasing by 1.13 mm (SE 0.35) per kilogram (P = 0.002). There was no significant relationship with measured muscle thickness.

CONCLUSION

Sonographic measurement of pyloric length is strongly correlated with the weight of the infant, irrespective of other factors. The relationship of length and weight may be useful in confirming the presence of HPS in small and premature infants.

Acute abdomen in infants of adolescent mothers: diagnostic challenges

Caring for children of adolescent parents presents unique challenges. Because adolescent parents may lack parenting skills and knowledge of medical terminology, symptoms of life-threatening illnesses may be misinterpreted. We present two cases of unexpected acute abdomen in young infants with adolescent mothers. The first case involves midgut volvulus, which was discovered during a routine newborn visit. The second case, involving pyloric stenosis, presented a clinical management challenge when the adolescent mother refused diagnostic studies.

Surgeon-performed ultrasound imaging in acute surgical disorders

As the role of the general surgeon continues to evolve, the surgeon's use of ultrasound imaging will surely influence practice patterns, particularly for the evaluation of patients in the acute setting. With the use of real-time imaging, the surgeon receives "instantaneous" information to augment the physical examination, to narrow the differential diagnosis, or to initiate an intervention. With select ultrasound examinations, the surgeon can rapidly evaluate adult and pediatric patients with an acute abdomen, especially those patients who are hypotensive. In the hands of the surgeon, this noninvasive, bedside tool can assess more accurately the presence, depth, and extent of an abscess, confirm complete aspiration, or diagnose wound dehiscence before it is apparent on physical examination. Ultrasound imaging is so accurate for the diagnosis of pyloric stenosis that it has essentially replaced the upper gastrointestinal series in most institutions. The surgeon's use of ultrasound imaging to detect a pleural effusion has virtually supplanted the lateral decubitus radiograph. Furthermore, an ultrasound-guided thoracentesis not only facilitates the procedure but improves its safety. As surgeons become more facile with ultrasound imaging, it is anticipated that other uses will develop to further enhance its value for the assessment of patients in the acute setting.

Ultrasonographic diagnosis criteria using scoring for hypertrophic pyloric stenosis

PURPOSE

For diagnosis of infantile hypertrophic pyloric stenosis (HPS), ultrasonography (US) is a useful and objective diagnostic method. In the current study, pyloric diameter, muscular thickness, and pyloric length were measured in normal infants (n = 26) and infants which is an adequate (n = 57). Each score was assigned to relevant measurements, and diagnostic criteria obtained with a scoring system were prepared using statistical skills by the probit analysis.

METHODS

For scoring, points were given to relevant measurements in conformity with the probit analysis. Zero points were given to patients with no possibility of HPS, 1 point to those with less than 25% probability, 2 points to those with 25% or more but less than 50% probability, and 3 points to patients with 50% or more probability. Points were totaled, and analysis was performed.

RESULTS

The composite score was evaluated by probit analysis, and cases with a composite score of 2 or less were all included in the normal group, whereas those with a composite score of 3 or more were all in the HPS group. Both groups could thereby be 100% identified.

CONCLUSION

US was able to diagnose cases with overall score of 2 or less as normal and those with overall score of 3 or higher as having HPS. In addition, after the current diagnostic criteria were prepared, preoperative diagnoses were performed prospectively using them for vomiting neonates and infants, and all cases were correctly discriminated and diagnosed. These findings indicate our ultrasonographic diagnosis criteria are useful for diagnosing HPS.

Infantile hypertrophic pyloric stenosis after pertussis prophylaxis with erythromcyin: a case review and cohort study

BACKGROUND

In February, 1999, a local US health department identified a cluster of pertussis cases among neonates born at a community hospital and recommended oral erythromycin for post-exposure prophylaxis for about 200 neonates born at that hospital between Feb 1 and Feb 24, 1999. We investigated a cluster of seven cases of infantile hypertrophic pyloric stenosis (IHPS) that occurred the following month among the neonates who had received erythromycin.

METHODS

We obtained a masked, independent review of the IHPS ultrasonography diagnoses, calculated the monthly IHPS incidence, and compared index and historical (1998-99) IHPS cases with respect to several characteristics including erythromycin exposure. We used a retrospective cohort of infants born in January and February, 1999, to investigate further erythromycin exposure and development of IHPS.

FINDINGS

An independent review confirmed the ultrasonographic diagnoses of all seven index IHPS cases. All index cases versus none of the historical IHPS cases had been given erythromycin for pertussis prophylaxis. The IHPS rate for infants born in the hospital in February, 1999, was 32.3 per 1000 liveborn infants, representing nearly a seven-fold increase over 1997-98 (relative risk 6.8 [95% CI 3.0-15.7]). Among infants born in January and February, 1999, erythromycin was associated with IHPS (absolute risk 4.5%, relative risk infinity [1.7-infinity]).

INTERPRETATION

Neonates receiving oral erythromycin may have an increased risk of IHPS. The risks and benefits of erythromycin for neonatal pertussis prophylaxis should be re-evaluated, and caution should be used in defining risk groups for prophylaxis.