Infantile hypertrophic pyloric stenosis: epidemiology, genetics, and clinical update

Neonatal anthropometric indicators of infant growth and mortality in Burkina Faso

OBJECTIVE

Most evidence supporting screening for undernutrition is for children aged 6-59 months. However, the highest risk of mortality and highest incidence of wasting occurs in the first 6 months of life. We evaluated relationships between neonatal anthropometric indicators, including birth weight, weight-for-age Z-score (WAZ), weight-for-length Z-score (WLZ), length-for-age Z-score (LAZ) and mid-upper arm circumference (MUAC) and mortality and growth at 6 months of age among infants in Burkina Faso.

DESIGN

Data arose from a randomised controlled trial evaluating neonatal azithromycin administration for the prevention of child mortality. We evaluated relationships between baseline anthropometric measures and mortality, wasting (WLZ < -2), stunting (LAZ < -2) and underweight (WAZ < -2) at 6 months of age were estimated using logistic regression models adjusted for the child's age and sex.

SETTING

Five regions of Burkina Faso.

PARTICIPANTS

Infants aged 8-27 d followed until 6 months of age.

RESULTS

Of 21 832 infants enrolled in the trial, 7·9 % were low birth weight (<2500 g), 13·3 % were wasted, 7·7 % were stunted and 7·4 % were underweight at enrolment. All anthropometric deficits were associated with mortality by 6 months of age, with WAZ the strongest predictor (WAZ < -2 to ≥ -3 at enrolment v. WAZ ≥ -2: adjusted OR, 3·91, 95 % CI, 2·21, 6·56). Low WAZ was also associated with wasting, stunting, and underweight at 6 months.

CONCLUSIONS

Interventions for identifying infants at highest risk of mortality and growth failure should consider WAZ as part of their screening protocol.

Controlled long term outcome of pyloromyotomy for pyloric stenosis: No long-term adverse effect

PURPOSE

Pyloromyotomy for pyloric stenosis is one of the more common surgical procedures performed on infants. The long-term effects of the procedure are however unclear. The purpose of this study was to study the effects into adult life, compare them with controls and to see if there is a need for structured follow up of patients.

METHODS

Of the 101 patients operated for pyloric stenosis between 1972 and 1974 at our tertiary referral center 91 could be traced. They were all invited to participate in the study and were sent validated questionnaires (PAGI-SYM, GIQLI) as well as a study-specific questionnaire examining the use of antacid drugs, incidence of gastroscopy and abdominal surgery. Sixty patients responded (66%, mean age 45 years, 46 male) and were included. Thereafter, 600 age and sex-matched controls were sent the same questionnaires. 132 responded (22%, 90 male) and were includes as controls.

RESULTS

No significant differences could be found in any of the examined parameters when looking at the whole material or the male patients. Female patients had higher PAGI-SYM-scores for post prandial fullness (mean 1.11 vs 0.43, P = 0.035) and heartburn (mean 0.59 vs 0.14, P = 0.043) when compared to controls.

CONCLUSIONS

The present study shows that most patients operated for pyloric stenosis during infancy experience no negative effects into adulthood. The finding in the female patient group is interesting but is unlikely to have any clinical implications. The results from this study strongly implicate that there is no need for follow up of patients into adulthood.

LEVEL OF EVIDENCE

Level III.

Environmental exposure in the etiology of infantile hypertrophic pyloric stenosis: a systematic review and meta-analysis

PURPOSE

To investigate the occupational and environmental factors in the etiology of infantile hypertrophic pyloric stenosis (IHPS).

METHODS

Protocol was drafted according to the PRISMA guidelines and registered on PROSPERO (CRD42020152460). A search for a combination of terms related to IHPS, fetus and neonates, and environmental exposure was performed for studies published between 2000 and 2020 in the EMBASE, Pubmed, and MEDLINE databases.

RESULTS

Overall, 2203 abstracts were identified and 829 were screened. The full text of the selected articles (N = 98) was assessed for eligibility. Fifteen studies were included in quantitative synthesis. IHPS risk was significantly lower in black and Hispanic mothers than in white mothers [OR 0.47 (95% CI 0.44-0.51, p < 0.001), OR 0.85 (95% CI 0.77-0.94, p = 0.002), respectively]. Lower maternal education level and maternal smoking were risk factor for IHPS. We further observed a non-significant association between maternal folic acid usage and IHPS risk. Data were insufficient to evaluate occupational exposure.

CONCLUSION

This review provides an understanding of the role of environmental exposures in IHPS etiology. Lower maternal educational level, maternal smoking, and white ethnicity are associated with a significantly increased risk of IHPS, while folic acid use seems non-significantly associated with IHPS risk.

LEVEL OF EVIDENCE

III.

Neonatal azithromycin administration for prevention of infant mortality

BACKGROUND: Biannual mass azithromycin administration reduces all-cause childhood mortality in some sub-Saharan African settings, with the largest effects in children 1 to 5 months of age. Azithromycin has not been distributed to children younger than 1 month of age because of the risk of infantile hypertrophic pyloric stenosis (IHPS). METHODS: In this 1:1 placebo-controlled trial, neonates 8 to 27 days of age were randomly assigned to a single oral dose of azithromycin (20 mg/kg) or an equivalent volume of placebo in five regions of Burkina Faso during 2019 and 2020. The primary outcome was all-cause mortality at 6 months of age. Infants were evaluated at 21 days after treatment and at 3 and 6 months of age for vital status; family and provider surveillance for IHPS continued throughout. RESULTS: Of 21,832 enrolled neonates, 10,898 were allocated to azithromycin and 10,934 to placebo. At 6 months of age, 92 infants had died: 42 (0.44%) in the azithromycin group and 50 (0.52%) in the placebo group (hazard ratio, 0.85; 95% confidence interval [CI], 0.56 to 1.28; P=0.46). A single IHPS case was detected, which was in the azithromycin arm. Serious adverse events, including death and hospitalization within 28 days of treatment, occurred in 0.27% of infants in the azithromycin group and 0.14% in the placebo group, for an absolute risk difference of 0.14 percentage points (95% CI, 0.01 to 0.26). CONCLUSIONS: Overall mortality was lower than anticipated when the trial was designed, thus limiting its power. The available data do not support the routine use of azithromycin for the prevention of mortality in neonates in sub-Saharan African settings similar to the one in which this trial was conducted. (Funded by the Bill and Melinda Gates Foundation; ClinicalTrials.gov number, NCT03682653.)

Gastrointestinal Emergency in Neonates and Infants: A Pictorial Essay

Gastrointestinal (GI) emergencies in neonates and infants encompass from the beginning to the end of the GI tract. Both congenital and acquired conditions can cause various GI emergencies in neonates and infants. Given the overlapping or nonspecific clinical findings of many different neonatal and infantile GI emergencies and the unique characteristics of this age group, appropriate imaging is key to accurate and timely diagnosis while avoiding unnecessary radiation hazard and medical costs. In this paper, we discuss the radiological findings of essential neonatal and infantile GI emergencies, including esophageal atresia and tracheoesophageal fistula, hypertrophic pyloric stenosis, duodenal atresia, malrotation, midgut volvulus for upper GI emergencies, and jejunoileal atresia, meconium ileus, meconium plug syndrome, meconium peritonitis, Hirschsprung disease, anorectal malformation, necrotizing enterocolitis, and intussusception for lower GI emergencies.

Brief Overview and Updates on Infantile Hypertrophic Pyloric Stenosis: Focus on Perioperative Management

Infantile hypertrophic pyloric stenosis is the most common surgical cause of vomiting in infancy. After adequate resuscitation, surgical pyloromyotomy is the standard of care for infants with pyloric stenosis. This article provides a brief overview and updates on hypertrophic pyloric stenosis in infants, with a focus on the surgical approach as well as perioperative management of this pathology. The most controversial aspect of the management of infants with pyloric stenosis is post-pyloromyotomy feeding, as there is no clear consensus in the literature on the best regimen. More randomized controlled trials are needed to establish the optimal resuscitation protocol in the preoperative phase and the ideal feeding regimen in the postoperative phase for infants with hypertrophic pyloric stenosis. [Pediatr Ann. 2021;50:(3):e136-e141.].

Protocol: A systematic review and meta-analysis of the role of fetal and infantile environmental exposure in etiopathogenesis of infantile hypertrophic pyloric stenosis

Infantile hypertrophic pyloric stenosis (IHPS) is one of the hallmark pediatric surgical diseases. However, its etiology remains incompletely understood. By systematically reviewing the literature, we aim to clarify the effect of the effect of occupational and environmental factors and role of nitric oxide (NO) metabolism in the etiopathogenesis of IHPS. The systematic review is drafted with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis statement (PRISMA) and the Meta-analysis of Observational Studies in Epidemiology (MOOSE). Systematic literature search will be performed for the period 2000 (Jan) to 2020 (Dec) in the databases: MEDLINE, EMBASE, PubMed. The systematic search will cover the literature in English and Turkish language and will be limited to studies on human subjects. Four investigators will independently search the databases (MEDLINE, EMBASE, PubMed) according to the defined search strategy. The full-text of the selected articles will be screened independently by four reviewers, against the inclusion criteria. Descriptive data will be extracted from each study regarding: study details, methods, participants, outcomes and calculations of association for potential further statistical analysis. If meta-analysis could not be undertaken, systematic approach to analyzing the findings of included multiple studies will be described. Heterogeneity will be assessed by quantifying the inconsistency across studies using I2 statistic. Statistical analysis will be performed using Comprehensive Meta-Analysis Version 3.0 software. The p values lower than 0.05 will be considered statistically significant for all analyses.

The Safety and Effectiveness of Laparoscopic versus Open Surgery for Congenital Hypertrophic Pyloric Stenosis in Infants

BACKGROUND This study aimed to investigate the safety and effectiveness of laparoscopic pyloromyotomy for infants with congenital hypertrophic pyloric stenosis. MATERIAL AND METHODS The clinical data of 233 infants with congenital hypertrophic pyloric stenosis who were treated at our hospital from January 2013 to January 2018 were analyzed retrospectively. The patients were divided into 2 groups: the laparoscopic group (group A, n=126) and the conventional operation group (group B, n=107). RESULTS Laparoscopic surgery was successfully performed in all patients in the laparoscopic group, and none of the surgeries were converted to open surgery. Compared with traditional surgery, laparoscopic surgery has obvious advantages in operation time (29.8±12.9 minutes versus 37.2±17.5 minutes, P=0.012), postoperative feeding time (10.3±2.2 hours versus 15.2±4.1 hours, P=0.035), postoperative hospitalization time (2.8±0.7 days versus 3.5±1.9 days, P=0.013), incision length (0.9±0.2 cm versus 3.3±0.8 cm, P=0.002) and poor wound healing (0 versus 6, P=0.007). No complications, such as bleeding, gastric perforation, duodenal injury, abdominal infection or recurrent vomiting, were observed in the 2 groups. The growth and development (weight and height) of the infants in both groups were normal. CONCLUSIONS Laparoscopic pyloromyotomy has the same safety and effectiveness as the traditional operation and has the advantages of less trauma, faster recovery and cosmetically pleasing incisions.

Pyloric Stenosis: National Trends in the Incidence Rate and Resource Use in the United States From 2012 to 2016

OBJECTIVES

Infantile hypertrophic pyloric stenosis (IHPS) is the most common reason for abdominal surgery in infants; however, national-level data on incidence rate and resource use are lacking. We aimed to examine the national trends in hospitalizations for IHPS and resource use in its management in the United States from 2012 to 2016.

METHODS

We performed a retrospective serial cross-sectional study using data from the National Inpatient Sample, the largest health care database in the United States. We included infants aged ≤1 year assigned an International Classification of Diseases, Ninth Revision, or International Classification of Diseases, 10th Revision, code for IHPS who underwent pyloromyotomy or pyloroplasty. We examined the temporal trends in the incidence rate (cases per 1000 live births) according to sex, insurance status, geographic region, and race. We examined resource use using length of stay (LOS) and hospital costs. Linear regression was used for trend analysis.

RESULTS

Between 2012 and 2016, there were 32 450 cases of IHPS and 20 808 149 live births (incidence rate of 1.56 per 1000). Characteristics of the study population were 82.7% male, 53% white, and 63.3% on Medicaid, and a majority were born in large (64%), urban teaching hospitals (90%). The incidence of IHPS varied with race, sex, socioeconomic status, and geographic region. In multivariable regression analysis, the incidence rate of IHPS decreased from 1.76 to 1.57 per 1000 (adjusted odds ratio 0.93; 95% confidence interval 0.92-0.93). The median cost of care was $6078.30, whereas the median LOS was 2 days, and these remained stable during the period.

CONCLUSIONS

The incidence rate of IHPS decreased significantly between 2012 and 2016, whereas LOS and hospital costs remained stable. The reasons for the decline in the IHPS incidence rate may be multifactorial.

Genome-wide association studies of structural birth defects: A review and commentary

BACKGROUND

While there is strong evidence that genetic risk factors play an important role in the etiologies of structural birth defects, compared to other diseases, there have been relatively few genome-wide association studies (GWAS) of these conditions. We reviewed the current landscape of GWAS conducted for birth defects, noting novel insights, and future directions.

METHODS

This article reviews the literature with regard to GWAS of structural birth defects. Key defects included in this review include oral clefts, congenital heart defects (CHDs), biliary atresia, pyloric stenosis, hypospadias, craniosynostosis, and clubfoot. Additionally, other issues related to GWAS are considered, including the assessment of polygenic risk scores and issues related to genetic ancestry, as well as utilizing genome-wide single nucleotide polymorphism array data to evaluate gene-environment interactions and Mendelian randomization.

RESULTS

For some birth defects, including oral clefts and CHDs, several novel susceptibility loci have been identified and replicated through GWAS, including 8q24 for oral clefts, DGKK for hypospadias, and 4p16 for CHDs. Relatively common birth defects for which there are currently no published GWAS include neural tube defects, anotia/microtia, anophthalmia/microphthalmia, gastroschisis, and omphalocele.

CONCLUSIONS

Overall, GWAS have been successful in identifying several novel susceptibility genes and genomic regions for structural birth defects. These findings have provided new insights into the etiologies of these phenotypes. However, GWAS have been underutilized for understanding the genetic etiologies of several birth defects.

Neonatal azithromycin administration to prevent infant mortality: study protocol for a randomised controlled trial

INTRODUCTION

Biannual mass azithromycin distribution to children aged 1-59 months has been shown to reduce all-cause mortality. Children under 28 days of age were not treated in studies evaluating mass azithromycin distribution for child mortality due to concerns related to infantile hypertrophic pyloric stenosis (IHPS). Here, we report the design of a randomised controlled trial to evaluate the efficacy and safety of administration of a single dose of oral azithromycin during the neonatal period.

METHODS AND ANALYSIS

The Nouveaux-nés et Azithromycine: une Innovation dans le Traitement des Enfants (NAITRE) study is a double-masked randomised placebo-controlled trial designed to evaluate the efficacy of a single dose of azithromycin (20 mg/kg) for the prevention of child mortality. Newborns (n=21 712) aged 8-27 days weighing at least 2500 g are 1:1 randomised to a single, directly observed, oral dose of azithromycin or matching placebo. Participants are followed weekly for 3 weeks after treatment to screen for adverse events, including IHPS. The primary outcome is all-cause mortality at the 6-month study visit.

ETHICS AND DISSEMINATION

This study was approved by the Institutional Review Boards at the University of California, San Francisco in San Francisco, USA (Protocol #18-25027) and the Comité National d'Ethique pour la Recherche in Ouagadougou, Burkina Faso (Protocol #2018-10-123). The findings of this trial will be presented at local, regional and international meetings and published in open access peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT03682653; Pre-results.

Association between exposure to macrolides and the development of infantile hypertrophic pyloric stenosis: a systematic review and meta-analysis

Macrolides are bacteriostatic antibiotics with a broad spectrum of activity against Gram-positive bacteria. The aim of this study was to systematically review and meta-analyze the association between infantile hypertrophic pyloric stenosis (IHPS) and macrolides. Nine databases were searched systematically for studies with information on the association between macrolides and IHPS. We combined findings using random effects models. Our study revealed 18 articles investigating the association between macrolides and IHPS. There was a significant association between the development of IHPS and erythromycin (2.38, 1.06-5.39). The association was strong when erythromycin was used during the first 2 weeks of life (8.14, 4.29-15.45). During breastfeeding, use of macrolides showed no significant association with IHPS in infants (0.96, 0.61-1.53). IHPS was not associated with erythromycin (1.11, 0.9-1.36) or macrolides use during pregnancy (1.15, 0.98-1.36).Conclusions: There is an association between erythromycin use during infancy and developing IHPS in infants. However, no significant association was found between macrolides use during pregnancy or breastfeeding. Additional large studies are needed to further evaluate potential association with macrolide use. What is known? • Erythromycin intake in the first 2 weeks of life is associated with an increased risk of pyloric stenosis. What is New? • There is currently no evidence of significant association between macrolides use during pregnancy or breastfeeding and pyloric stenosis.

The association of prenatal and postnatal macrolide exposure with subsequent development of infantile hypertrophic pyloric stenosis: a systematic review and meta-analysis

Background

The association between macrolides use and subsequent occurrence of infantile hypertrophic pyloric stenosis (IHPS) is still debatable. The aim of this study was to conduct a systematic review and meta-analysis of the association between perinatal exposure to macrolides, mainly erythromycin, and the development of pyloric stenosis.

Methods

Original studies were identified using MEDLINE, Web of Science, Scopus, Google Scholar, and the Cochrane Library databases. Studies investigating the association between perinatal exposure to macrolides and pyloric stenosis were included. The most adjusted effect estimates were pooled using random-effects meta-analysis. The I² and Egger’s tests were used to assess heterogeneity and publication bias, respectively.

Results

Fourteen papers (12 retrospective cohort studies and two case-control studies) were included. For postnatal exposure, the overall estimate of seven cohort studies indicated a statistically significant association (RR = 3.17, 95% CI: 2.38–4.23; I² = 10.0%) with no evidence of publication bias (Egger P = 0.81). For prenatal exposure, six cohort studies and two case-control studies were included. Meta-analysis demonstrated a statistically significant association in the cohort studies (OR = 1.47, 95% CI: 1.03–2.09; I² = 29.3%), but not in the case-control studies (OR = 1.02, 95% CI: 0.66–1.58; I² = 51.2%). The overall pooled result was not statistically significant. Only two studies were included for exposure through breastfeeding, and the estimates did not show a statistically significant association (OR = 1.31; 95% CI: 0.42–4.1; I² = 69.1%).

Conclusions

The study demonstrated good evidence of association between development of IHPS and direct postnatal exposure to macrolides. However, the evidence on the effects of prenatal exposure or postnatal maternal exposure (breastfeeding) is not conclusive.

Neonatal Bowel Disorders: Practical Imaging Algorithm for Trainees and General Radiologists

OBJECTIVE

Neonatal bowel disorders require prompt and accurate diagnosis to avoid potential morbidity and mortality. Symptoms such as feeding intolerance, emesis, or failure to pass meconium may prompt a radiologic evaluation.

CONCLUSION

We discuss the most common neonatal bowel disorders and present a practical imaging algorithm for trainees and general radiologists.

Application of color Doppler ultrasound combined with Doppler imaging artifacts in the diagnosis and estimate of congenital hypertrophic pyloric stenosis

Congenital Hypertrophic Pyloric Stenosis (CHPS) is a disease condition that is caused as a result of pylorus wall hypertrophy and hyperplasia. In this study, we used color Doppler flow imaging (CDFI) and Doppler artifacts technique to observe the blood flow of hypertrophic pylorus tissue and the dynamic imaging of liquid passing through the pyloric canal in CHPS infants. 65 cases of CHPS infants and 50 infants without CHPS served as control group. We found that there were statistically significant differences between the blood flow grade of muscular layer and mucosal layer between CHPS and control infants, but no significant differences were observed in the same group. Doppler artifacts technique demonstrated the whole process of contrast agent flow through pyloric canal was directly observed in 35 of 65 subjects, and the internal diameter of the pyloric canal was 1.93 ± 0.33mm.Conclusion that CDFI combined with color Doppler artifacts technique was proved to be effective to observe the distribution feature and blood flow grade in each layer of pyloric canal in CHPS patients. This method provides the evidence for judging the degree of pyloric stenosis clinically, and furnishes the basis of therapy along with its clinical significance and good application value.

Epidemiological and clinical characteristics of 304 patients with infantile hypertrophic pyloric stenosis in Anhui Province of East China, 2012-2015

OBJECTIVE

To analyze the clinical and epidemiological features of patients with infantile hypertrophic pyloric stenosis (IHPS) so as to provide scientific evidence for diagnosis and prevention of IHPS.

METHODS

We performed a retrospective study of infants with IHPS diagnosed from 2012 to 2015 at Anhui Provincial Children's Hospital. Demographic characteristics and clinical data were collected.

RESULTS

Three hundred four patients (264 males and 40 females) were studied, of which 94.7% were full term and 75.7% were bottle fed or mixed fed; 16.8% of the patients had other congenital malformations in combination with IHPS. The proportion of IHPS cases with hyponatremia, hypokalemia, and hypochloremia was 18.4%, 12.5%, and 53.9%. A negative correlation was found between duration of disease and serum electrolytes. The mean pyloric muscle thickness, pyloric length, and diameter were 4.8 ± 0.7 mm, 19.4 ± 2.5 mm, and 13.3 ± 1.8 mm, respectively. There were significant differences in muscle thickness, pyloric length, and diameter between short (≤14 d) and long (>14 d) durations of disease. All patients underwent pyloromyotomy, and postoperative recovery was good.

CONCLUSIONS

IHPS occurs mainly in male, full-term, bottle-fed or mixed-fed infants. Patients with long duration of disease were more likely to develop electrolyte disorder and thicker muscle layer. More attention should be paid to early discovery and diagnosis, which will help to improve the curative effect and prognosis of IHPS.

Implementation of a care pathway for infantile hypertrophic pyloric stenosis reduces length of stay and increases parent satisfaction

Introduction

Infantile hypertrophic pyloric stenosis (IHPS) is a common surgical condition, but there are no guidelines regarding preoperative fluid resuscitation. Our aim was to evaluate a novel consensus care pathway for IHPS, incorporating a standardized fluid and electrolyte replacement regime.

Methods

One hundred patients were initially reviewed and compared to thirty-three patients following the introduction of a clinical pathway, whereby infants requiring electrolyte correction received 150 ml/kg/24 h of 0.45% saline, 5% dextrose and 10 mmol KCl, with systematic blood sampling until correction was achieved. We measured time to electrolyte correction, time to surgery and total length of hospitalization. Data were described using the median and interquartile range, and differences between the groups’ categorical and continuous data were described using Chi-squared and the Mann–Whitney U–tests, respectively.

Results

Time in hours taken to correct electrolytes was reduced: 25(16.5–42) versus 9.5(4.5–24.75) p = 0.004. Time to surgery from admission in uncorrected patients decreased from 50(40.25–66.75) to 39(28.75–41.75) p = 0.018. Subsequently, there was a reduction in total length of stay: 94(71–93.5) versus 75(64.5–93.5) p = 0.025. Parental satisfaction increased from 77% in the pre-pathway group to 83% in the pathway group.

Conclusion

A consensus care pathway for IHPS reduces the time taken to correct preoperative electrolyte abnormalities, decreases length of hospitalization and improves parental satisfaction.

Maternal factors in the origin of infantile hypertrophic pyloric stenosis: A population-based case-control study

In most patients affected by isolated infantile hypertrophic pyloric stenosis (IHPS) the etiology is largely unknown. Thus, the aim of this study was to estimate possible maternal risk factors in the origin of IHPS. The study samples included 241 cases with IHPS, 357 matched controls and 38,151 population controls without any defect in the population-based large dataset of the Hungarian Case-Control Surveillance of Congenital Abnormalities, 1980-1996. Exposures that had been medically recorded in prenatal maternity logbooks during the critical period of IHPS were evaluated separately. The findings of this case-control study suggested that--beyond the well-known robust male excess (85.5%)--maternal hyperthyroidism (OR with 95% CI: 4.17, 1.53-11.38) and oral nalidixic acid treatment (OR with 95% CI: 6.53, 3.03-14.06) associated with a higher risk for IHPS in their children. In conclusion, our findings suggest that cases with IHPS had mothers with a higher proportion of hyperthyroidism and nalidixic acid treatment during pregnancy.

Birth outcomes of male and female patients with infantile hypertrophic pyloric stenosis--a population-based case-control study

OBJECTIVE

Most of the patients are affected by isolated infantile hypertrophic pyloric stenosis (IHPS) beyond the polygenic predisposition, the other factors in the multifactorial etiology are largely unknown. The main characteristic of IHPS is the robust male predominance, thus the aim of this study was to analyze birth outcomes in males and females whether they are different or not.

METHODS

The study samples included 241 cases with IHPS, 357 matched, and 38,151 population controls without any defect in the population-based large dataset of the Hungarian Case-Control Surveillance of Congenital Abnormalities, 1980-1996.

RESULTS

The findings of this case-control study confirmed the well-known strong male excess (85.5%). The mean gestational age was somewhat longer and it is associated with a lower rate of preterm births. Mean birth weight did not show significant differences among the study groups, but the rate of low birthweight was higher in cases with IHPS. However, these differences were found only in males. Thus, intrauterine fetal growth restriction is characteristic only for male cases with IHPS.

CONCLUSIONS

Our study confirmed the well-known obvious male excess of cases with IHPS, but our findings suggest some differences in birth outcomes of male and female cases. Male cases with IHPS had intrauterine fetal growth restriction while females did not. These data may indicate some differences in the pathogenesis of IHPS in males and females.

Advances in infantile hypertrophic pyloric stenosis

Infantile hypertrophic pyloric stenosis (IHPS) is a common condition in infancy, characterized by an acquired narrowing of the pylorus, which requires surgery. These infants usually present with projectile, nonbilious vomiting, with a palpable 'olive' in the abdomen and sometimes a 'peristaltic wave' after being fed with formula or breast milk. Although IHPS is a common disorder, its etiology is largely unknown. Surgical intervention is the standard treatment, preoperative preparation, however is essential to optimal outcome. In this review, the latest advances in IHPS regarding epidemiology, etiology, diagnostics and treatment will be discussed.

Use of macrolides in mother and child and risk of infantile hypertrophic pyloric stenosis: nationwide cohort study

OBJECTIVE

To assess the association between use of macrolide antibiotics in mothers and infants from pregnancy onset until 120 days after birth and infantile hypertrophic pyloric stenosis (IHPS).

DESIGN

Nationwide register based cohort study.

SETTING

Denmark, 1996-2011.

PARTICIPANTS

999,378 liveborn singletons and linked individual level information on macrolide prescriptions (maternal use during pregnancy, n=30,091; maternal use after birth, n=21,557; use in infants, n=6591), surgery for IHPS, and potential confounders.

MAIN OUTCOME MEASURES

Surgery for IHPS by three categories of macrolide use: in mothers during pregnancy, in mothers after birth, and in infants after birth.

RESULTS

880 infants developed IHPS (0.9 cases per 1000 births). Compared with infants with no use of macrolides, the adjusted rate ratio for IHPS in infants with use of macrolides during days 0 to 13 after birth was 29.8 (95% confidence interval 16.4 to 54.1) and during days 14 to 120 was 3.24 (1.20 to 8.74); the corresponding absolute risk differences were 24.4 (95% confidence interval 13.0 to 44.1) and 0.65 (0.06 to 2.21) cases per 1000 infants exposed to macrolides, respectively. The rate ratio for maternal use of macrolides for days 0 to 13 after birth was 3.49 (1.92 to 6.34) and for days 14 to 120 was 0.70 (0.26 to 1.90); the corresponding absolute risk differences were 2.15 (0.82 to 4.64) and -0.11 (-0.26 to 0.31). The rate ratios for maternal use of macrolides during pregnancy were 1.02 (0.65 to 1.59) for weeks 0 to 27 and 1.77 (0.95 to 3.31) for weeks 28 to birth; the corresponding absolute risk differences were 0.01 (-0.31 to 0.50) and 0.67 (-0.06 to 2.02).

CONCLUSIONS

Treatment of young infants with macrolide antibiotics was strongly associated with IHPS and should therefore only be administered if potential treatment benefits outweigh the risk. Maternal use of macrolides during the first two weeks after birth was also associated with an increased risk of IHPS. A possible association was also found with use during late pregnancy.

Proper development of the outer longitudinal smooth muscle of the mouse pylorus requires Nkx2-5 and Gata3

BACKGROUND & AIMS

Infantile hypertrophic pyloric stenosis is a common birth anomaly characterized by obstruction of the pyloric lumen. A genome-wide association study implicated NKX2-5, which encodes a transcription factor that is expressed in embryonic heart and pylorus, in the pathogenesis of infantile hypertrophic pyloric stenosis. However, the function of the NKX2-5 in pyloric smooth muscle development has not been examined directly. We investigated the pattern of Nkx2-5 during the course of murine pyloric sphincter development and examined coexpression of Nkx2-5 with Gata3 and Sox9-other transcription factors with pyloric-specific mesenchymal expression. We also assessed pyloric sphincter development in mice with disruption of Nkx2-5 or Gata3.

METHODS

We used immunofluorescence analysis to compare levels of NKX2-5, GATA3, and SOX9 in different regions of smooth muscle cells. Pyloric development was assessed in mice with conditional or germline deletion of Nkx2-5 or Gata3, respectively.

RESULTS

Gata3, Nkx2-5, and Sox9 are coexpressed in differentiating smooth muscle cells of a distinct fascicle of the pyloric outer longitudinal muscle. Expansion of this fascicle coincides with development of the pyloric sphincter. Disruption of Nkx2-5 or Gata3 causes severe hypoplasia of this fascicle and alters pyloric muscle shape. Although expression of Sox9 requires Nkx2-5 and Gata3, there is no apparent hierarchical relationship between Nkx2-5 and Gata3 during pyloric outer longitudinal muscle development.

CONCLUSIONS

Nkx2-5 and Gata3 are independently required for the development of a pyloric outer longitudinal muscle fascicle, which is required for pyloric sphincter morphogenesis in mice. These data indicate that regulatory changes that alter Nkx2-5 or Gata3 expression could contribute to pathogenesis of infantile hypertrophic pyloric stenosis.

Plasma lipids, genetic variants near APOA1, and the risk of infantile hypertrophic pyloric stenosis

IMPORTANCE

Infantile hypertrophic pyloric stenosis (IHPS) is a serious condition in which hypertrophy of the pyloric sphincter muscle layer leads to gastric outlet obstruction. Infantile hypertrophic pyloric stenosis shows strong familial aggregation and heritability, but knowledge about specific genetic risk variants is limited.

OBJECTIVES

To search the genome comprehensively for genetic associations with IHPS and validate findings in 3 independent sample sets.

DESIGN, SETTING, AND PARTICIPANTS

During stage 1, we used reference data from the 1000 Genomes Project for imputation into a genome-wide data set of 1001 Danish surgery-confirmed samples (cases diagnosed 1987-2008) and 2371 disease-free controls. In stage 2, the 5 most significantly associated loci were tested in independent case-control sample sets from Denmark (cases diagnosed 1983-2010), Sweden (cases diagnosed 1958-2011), and the United States (cases diagnosed 1998-2005), with a total of 1663 cases and 2315 controls.

MAIN OUTCOMES AND MEASURES

Association of genetic variation with the presence of infantile hypertrophic pyloric stenosis.

RESULTS

We found a new genome-wide significant locus for IHPS at chromosome 11q23.3. The single-nucleotide polymorphism (SNP) with the lowest P value at the locus, rs12721025 (odds ratio [OR], 1.59; 95% CI, 1.38-1.83; P = 1.9 × 10(-10)), is located 301 bases downstream of the apolipoprotein A-I (APOA1) gene and is correlated (r2 between 0.46 and 0.80) with SNPs previously found to be associated with levels of circulating cholesterol. For these SNPs, the cholesterol-lowering allele consistently was associated with increased risk of IHPS.

CONCLUSIONS AND RELEVANCE

This study identified a new genome-wide significant locus for IHPS. Characteristics of this locus suggest the possibility of an inverse relationship between levels of circulating cholesterol in neonates and IHPS risk, which warrants further investigation.

Impact of rocuronium vs succinylcholine neuromuscular blocking drug choice for laparoscopic pyloromyotomy: is there a difference in time to transport to recovery?

OBJECTIVES/AIM

This study evaluates the relationship between neuromuscular blocking drug administered and transport time following laparoscopic pyloromyotomy.

BACKGROUND

Infants with pyloric stenosis have indication for rapid sequence induction. While succinylcholine has rapid onset and short duration, its use in children may be associated with rare serious adverse effects. Rocuronium is a widely accepted alternative, but its duration could contribute to delay at surgery end.

METHODS

Infants undergoing laparoscopic pyloromyotomy at Loma Linda University Medical Center Children's Hospital from January 2006 to July 2011 were studied retrospectively. Only term infants receiving propofol induction, sevoflurane maintenance, no intraoperative opioid, and rocuronium, succinylcholine, or both were included. The primary outcome measure was time to transport after surgery stop as a measure of recovery from both anesthesia and relaxant. Data was analyzed for relationships between drug choice and time to transport.

RESULTS

 Data from 246 patients was analyzed. Patients were similar in all groups. Time to transport was not affected by doses of propofol or neuromuscular blocking drug, anesthesia to surgery end interval or surgery length. Time to transport (minutes median, interquartile range) was 13 (7-21) in patients receiving only succinylcholine compared to 18 (11-24) in those receiving only rocuronium (P=0.03).

CONCLUSIONS

For laparoscopic pyloromyotomy in term infants using propofol, sevoflurane and no intraoperative opioid, succinylcholine may be the best neuromuscular blocking drug choice, provided no contraindication is present. However, based on the small difference in time to transport, rocuronium as administered herein may be a reasonable alternative preferred by some clinicians.

Citrullinemia type I and hypertrophic pyloric stenosis in a 1-month old male infant

Citrullinemia type I (CTLN1) is an inherited urea cycle disorder, now included in most newborn screening panels in the US and Europe. Due to argininosuccinate synthetase deficiency, CTLN1 can lead to recurrent hyperammonemic crisis that may result in permanent neurologic sequelae. Vomiting in patients with urea cycle disorders may either be the result or cause of acute hyperammonemia, particularly if due to an illness that leads to catabolism. Therefore, age-appropriate common etiologies of vomiting must be considered when evaluating these patients. We present a 1-month old male infant with CTLN1 who had a 1-week history of vomiting and was discovered to have hypertrophic pyloric stenosis. This is the first documented case of an infant with CTLN1 who was later diagnosed with hypertrophic pyloric stenosis, and only the second case of concomitant disease.

Congenital pyloric mucosal fold resulting in an antral valve outflow obstruction in a bull terrier

An under-sized three-month-old female bull terrier was referred with a history of regurgitation since three days of age. Thoracic radiographs were unremarkable, while abdominal radiographs showed a distended stomach, despite a 12 hour fast. Abdominal ultrasonography revealed gastric outflow obstruction of unclear aetiology. Coeliotomy was performed, during which an excessive mucosal fold at the pyloric antrum was excised. Histopathology of the pyloric fold revealed mild oedema and fibrosis of the mucosal tissue. The dog made a complete recovery, with resolution of regurgitation and grew to within the expected breed size. In the authors' opinion, this is the first canine report of congenital antral mucosal valve resulting in gastric outflow obstruction, and only the second report in any species.

Infantile hypertrophic pyloric stenosis--genetics and syndromes

Infantile hypertrophic pyloric stenosis (IHPS) is a common condition in neonates that is characterized by an acquired narrowing of the pylorus. The aetiology of isolated IHPS is still largely unknown. Classic genetic studies have demonstrated an increased risk in families of affected infants. Several genetic studies in groups of individuals with isolated IHPS have identified chromosomal regions linked to the condition; however, these associations could usually not be confirmed in subsequent cohorts, suggesting considerable genetic heterogeneity. IHPS is associated with many clinical syndromes that have known causative mutations. Patients with syndromes associated with IHPS can be considered as having an extreme phenotype of IHPS and studying these patients will be instrumental in finding causes of isolated IHPS. Possible pathways in syndromic IHPS include: (neuro)muscular disorders; connective tissue disorders; metabolic disorders; intracellular signalling pathway disturbances; intercellular communication disturbances; ciliopathies; DNA-repair disturbances; transcription regulation disorders; MAPK-pathway disturbances; lymphatic abnormalities; and environmental factors. Future research should focus on linkage analysis and next-generation molecular techniques in well-defined families with multiple affected members. Studies will have an increased chance of success if detailed phenotyping is applied and if knowledge about the various possible causative pathways is used in evaluating results.

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.

Pre- and perinatal risk factors for pyloric stenosis and their influence on the male predominance

Pyloric stenosis occurs with a nearly 5-fold male predominance. To what extent this is due to environmental factors is unknown. In a cohort of all children born in Denmark, 1977-2008, the authors examined the association between pre- and perinatal exposures and pyloric stenosis and investigated whether these factors modified the male predominance. Information on pre- and perinatal factors and pyloric stenosis was obtained from national registers. Poisson regression models were used to estimate rate ratios. Among 1,925,313 children, 3,174 had surgery for pyloric stenosis. The authors found pyloric stenosis to be significantly associated with male sex, age between 2 and 7 weeks, early study period, being first born, maternal smoking during pregnancy, preterm delivery, small weight for gestational age, cesarean section, and congenital malformations. Among cases, 2,595 were males and 579 were females. Lower male predominance was associated with age at diagnosis outside the peak ages, early study period, no maternal smoking during pregnancy, preterm delivery, and congenital malformations. The authors have previously found a strong familial aggregation of pyloric stenosis indicating a genetic influence. This study shows that environmental factors during and shortly after pregnancy also play a role and that several of these modify the strong male predominance.

Decline in infantile hypertrophic pyloric stenosis in Germany in 2000-2008

BACKGROUND AND OBJECTIVE

The incidence of infantile hypertrophic pyloric stenosis (IHPS) is highly variable over time and geographic regions. A decline in IHPS incidence was recently reported in Sweden, the United States, Denmark, and Scotland. In Sweden, the IHPS decline seemed to be concurrent with a declining incidence in sudden infant death syndrome (SIDS), which suggested a common cause; the latter was attributed to campaigns against the prone sleeping position. We investigated the time course of the IHPS incidence in all German federal states (N = 16) between 2000 and 2008. We examined correlations between the IHPS incidence and the SIDS incidence.

METHODS

Data were extracted from the public report of health (Gesundheitsberichterstattung des Bundes). We collected the numbers of IHPS (International Classification of Diseases, 10th Revision [ICD-10], code 40.0), SIDS (ICD-10, R95), and live births (LB; male/female) in each federal state for 2000-2008.

RESULTS

The IHPS incidence declined in Germany from 2000 (3.2086/1000 LB [range: 1.67-5.33]) to 2008 (2.0175/1000 LB [1.74-3.72]; P = .005). The recorded incidence was highly variable in different federal states and over time. The SIDS incidence also declined during the same time period (2000, median: 0.759/1000 LB [interquartile range: 0.54-1.029]; 2008, median: 0.416/1000 LB [interquartile range: 0.285-0.6485]; P = .0255). However, the SIDS regional distribution was different from that of IHPS.

CONCLUSIONS

The IHPS incidence declined by ∼38% nationwide. A parallel decline in SIDS displayed a different pattern in regional distribution; thus, a common cause was unlikely. The regional differences indicated that etiologic factors remained unresolved.

Common variants near MBNL1 and NKX2-5 are associated with infantile hypertrophic pyloric stenosis

Infantile hypertrophic pyloric stenosis (IHPS) is a severe condition characterized by hypertrophy of the pyloric sphincter muscle. We conducted a genome-wide association study (GWAS) on 1,001 surgery-confirmed cases and 2,401 controls from Denmark. The six most strongly associated loci were tested in a replication set of 796 cases and 876 controls. Three SNPs reached genome-wide significance. One of these SNPs, rs11712066 (odds ratio (OR) = 1.61; P = 1.5 × 10(-17)) at 3p25.1, is located 150 kb upstream of MBNL1, which encodes a factor that regulates splicing transitions occurring shortly after birth. The second SNP, rs573872 (OR = 1.41; P = 4.3 × 10(-12)), maps to an intergenic region at 3p25.2 approximately 1.3 Mb downstream of MBNL1. The third SNP, rs29784 (OR = 1.42; P = 1.5 × 10(-15)) at 5q35.2, is 64 kb downstream of NKX2-5, which is involved in development of cardiac muscle tissue and embryonic gut development.

Gastroparesis: concepts, controversies, and challenges

Patients with gastroparesis often present a challenge to the treating physician. Postprandial symptoms with nausea and vomiting may not only lead to nutritional and metabolic consequences, but also cause significant disruptions to social activities that often center around food. While the definition of gastroparesis focuses on impaired gastric emptying, treatment options that affect gastric function are limited and often disappointing. The female predominance, the mostly idiopathic nature of the illness with a common history of abuse, and coexisting anxiety or depression show parallels with other functional disorders of the gastrointestinal tract. These parallels provided the rationale for some initial studies investigating alternative therapies that target the brain rather than the stomach. This emerging shift in medical therapy comes at a time when clinical studies suggest that gastric electrical stimulation may exert its effects by modulating visceral sensory processing rather than altering gastric motility. Physiologic and detailed anatomic investigations also support a more complex picture with different disease mechanisms, ranging from impaired accommodation to apparent visceral hypersensitivity or decreased interstitial cells of Cajal to inflammatory infiltration of myenteric ganglia. Delayed gastric emptying remains the endophenotype defining gastroparesis. However, our treatment options go beyond prokinetics and may allow us to improve the quality of life of affected individuals.