Perinatal risk factors for infantile hypertrophic pyloric stenosis: A systematic review and meta-analysis.

BACKGROUND: Infantile hypertrophic pyloric stenosis (IHPS) is one of the most common diseases that require surgical intervention amongst the paediatric population. Although the treatment and the diagnosis of pyloric stenosis are well established, the perinatal risk factors associated with it still need further investigation. METHODS: We searched the following databases: Cochrane, Google Scholar, PubMed, and Scopus. Studies were included if they were case-control or cohort in design and studied the perinatal risk factors associated with IHPS. The quality of the included studies was assessed using the Newcastle-Ottawa scale (NOS). RESULTS: Twenty-one articles were included in this meta-analysis, including 18,104,753 participants. Our analysis showed a significant association between IHPS and male sex (RR=2.71, 95% CI:1.93-3.78), maternal smoking (RR=1.75, 95% CI: 1.54 - 2.00), bottle-feeding (RR=1.68, 95% CI: 1.42 - 1.98), being first born (RR=1.23, 95% CI:1.07-1.40), African ethnicity (RR=0.51, 95% CI: 0.35-0.75), and cesarean section (RR=1.57, 95% CI: 1.49-1.66). On the contrary, there was no significant association between IHPS and multiple gestations, preterm labour, being born in summer, and small for gestational age (SGA). CONCLUSION: In conclusion, our analysis showed that male sex, bottle feeding, maternal smoking and African ethnicity were significantly associated with the risk of IHPS. However, most of the included articles were retrospective in design which necessitates conducting future prospective well-designed studies to further investigate the risk factors of IHPS.

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.

Infantile hypertrophic pyloric stenosis in Bosnia and Herzegovina: A retrospective cohort study from the largest tertiary care facility.

BACKGROUND: Infantile hypertrophic pyloric stenosis (IHPS) is the most common condition requiring surgery in infancy, but the etiology of IHPS is still unclear. The study aimed to analyze the epidemiological and clinical features of the infants with IHPS in our setting and determine the yearly trends in IHPS incidence in the Sarajevo Canton between 2007 and 2016. METHODS: We retrospectively analyzed epidemiologic, clinical, and operative data of all infants undergoing pyloromyotomy for IHPS over ten years in the largest tertiary care facility in Bosnia and Herzegovina. RESULTS: Fifty-three IHPS patients were diagnosed, yielding an overall incidence of 1.17 per 1000 live births (1.25 and 1.09 cases in 2007-2011 and 2012-2016, respectively). IHPS was more prevalent among male infants (ratio 6.6:1, p < 0.001). The mean age at onset of symptoms was 39.6 days (range, 17-107 days). The estimated median time from symptoms onset to hospitalization was 11 days (range, 1-17 days). The mean age at diagnosis was significantly longer in premature infants compared with term infants (p = 0.003). Both first-born rank and bottle-feeding were significantly associated with IHPS (p = 0.001 and p = 0.04, respectively). No seasonal variation associated with IHPS was detected (p = 0.25). No evidence was found of differences in the incidence of IHPS related to maternal age (p = 0.24) and smoking (p = 0.59). CONCLUSION: Our data indicate a declining trend and provide insights into the clinical characteristics of IHPS in Bosnia and Herzegovina. Most of the obtained results are in line with the published data and could improve the quality of local pediatric services.

The incidence of infantile hypertrophic pyloric stenosis nearly halved from 2005 to 2017: analysis of German administrative data.

PURPOSE: Some paediatric surgical diseases showed a declining incidence in recent years, among which hypertrophic pyloric stenosis has been particularly striking shortly in the years after the millennium. We aimed to assess whether this development continued over the following decade, as it might offer the chance to better understand the underlying reasons. METHODS: We analysed data files obtained from the German federal statistics office for principal diagnosis of hypertrophic pyloric stenosis and pyloromyotomies from 2005 to 2017. Changes over time were assessed via linear regression for incidences per 1000 live births. RESULTS: In the respective time interval, there were a mean of 1009 pyloromyotomies (95% CI 906-1112) per year, of which a mean of 835 (95% CI 752-917) were performed in boys. The incidence of hypertrophic pyloric stenosis per 1000 live births almost halved between 2005 and 2017: it decreased by 0.12 pylorotomies annually (95% CI 0.09-0.14; P < 0.0001) in boys-from a maximum of 2.96 to a minimum of 1.63-and 0.03 pyloromyotomies annually (95% CI 0.02-0.04; P < 0.0001) in girls-from a maximum of 0.64 to a minimum of 0.28. There was considerable regional variation in incidences between the German länder. CONCLUSION: The decreasing incidence of hypertrophic pyloric stenosis noted around the millenium continued into the following decades. The underlying reasons are unclear, which should prompt further research on the subject matter.

The Dutch Incidence of Infantile Hypertrophic Pyloric Stenosis and the Influence of Seasons.

INTRODUCTION: Studies report contradicting results on the incidence of infantile hypertrophic pyloric stenosis (IHPS) and its association with seasons. We aim to assess the IHPS incidence in the Netherlands and to determine whether seasonal variation is present in a nationwide cohort. MATERIALS AND METHODS: All infants with IHPS hospitalized in the Netherlands between 2007 and 2017 were included in this retrospective cohort study. Incidence rates per 1,000 livebirths (LB) were calculated using total number of LB during the matched month, season, or year, respectively. Seasonal variation based on month of birth and month of surgery was analyzed using linear mixed model and one-way ANOVA, respectively. RESULTS: A total of 2,479 infants were included, of which the majority was male (75.9%). Median (interquartile range) age at surgery was 34 (18) days. The average IHPS incidence rate was 1.28 per 1,000 LB (variation: 1.09-1.47 per 1,000 LB). We did not find a conclusive trend over time in IHPS incidence. Differences in incidence between season of birth and season of surgery were not significant (p = 0.677 and p = 0.206, respectively). CONCLUSION: We found an average IHPS incidence of 1.28 per 1,000 LB in the Netherlands. Our results showed no changing trend in incidence and no seasonal variation.

Características clínico-epidemiológicas en pacientes con estenosis hipertrófica del píloro. Estudio de 15 años en un centro terciario / Clinic-epidemiological characteristics in patients with hypertrophic pyloric stenosis. 15-year study in a tertiary center

La estenosis hipertrófica del píloro está caracterizada por una hipertrofia e hiperplasia de las fibras musculares y estrechamiento del canal pilórico, que provoca vómitos no biliosos, dando lugar a una de las causas más comunes de tratamiento quirúrgico en la etapa de recién nacido. Se realizó un estudio descriptivo retrospectivo en 119 pacientes con el diagnóstico de estenosis hipertrófica del píloro en el Hospital Pediátrico Universitario William Soler desde el año 2000 al 2015. El 70,6 por ciento de los niños tenía entre tres y cinco semanas de nacido y el 83,2 por ciento un peso al diagnóstico entre 2500 g a 4500 g. El vómito estuvo presente en todos los pacientes, las alteraciones del peso corporal en 79,8 `por ciento y los desequilibrios hidroelectrolíticos y acido básico en el 53,8 por ciento. El sexo masculino, apariencia racial blanca, ser primogénito y la lactancia artificial o mixta, fueron factores de riesgos prevalentes significativos asociados a la enfermedad (p<0.05). La estenosis hipertrófica del píloro se diagnosticó con mayor frecuencia a la 4ta semana de vida y en niños con un peso entre 3000 a 4500 g. Las variaciones ponderales denotan la importancia del seguimiento de la curva de peso en estos pacientes(AU)

Hypertrophic pyloric stenosis is characterized by hypertrophy and hyperplasia of the muscle fibers and narrowing of the pyloric canal, which causes non-bilious vomiting, giving rise to one of the most common causes of surgical treatment in the newborn stage. A retrospective descriptive study was carried out in 119 patients with a diagnosis of hypertrophic pyloric stenosis at the William Soler University Pediatric Hospital from 2000 to 2015. 70.6 percent of the children were between three and five weeks old and 83.2 percent a weight at diagnosis between 2500 g to 4500 g. Vomiting was present in all patients, alterations in body weight in 79.8 percent and hydroelectrolyte and basic acid imbalances in 53.8 percent. Male sex, white racial appearance, being first-born, and artificial or mixed breastfeeding were significant prevalent risk factors associated with the disease (p <0.05). Hypertrophic pyloric stenosis was most frequently diagnosed at the 4th week of life and in children weighing between 3000 and 4500 g. The weight variations denote the importance of following the weight curve in these patients(EU)

Safety of azithromycin in pediatrics: a systematic review and meta-analysis.

PURPOSE: To evaluate the toxicity of azithromycin in neonates, infants, and children. METHODS: A systematic review was performed for relevant studies using Medline (Ovid), PubMed, Cochrane Central Register of Controlled Trials, EMBASE, CINAHL, and International Pharmaceutical Abstracts. We calculated the pooled incidence of adverse drug reactions (ADRs) associated with azithromycin based on prospective studies (RCTs and prospective cohort studies) and analyzed the risk difference (RD) of ADRs between azithromycin and placebo or other antibiotics using meta-analysis of RCTs. RESULTS: We included 133 studies with 4243 ADRs reported in 197,675 neonates, infants, and children who received azithromycin. The safety of azithromycin as MDA in pediatrics was poorly monitored. The main ADRs were diarrhea and vomiting. In prospective non-MDA studies, the most common toxicity was gastrointestinal ADRs (938/1967; 47.7%). The most serious toxicities were cardiac (prolonged QT or irregular heart beat) and idiopathic hypertrophic pyloric stenosis (IHPS). Compared with placebo, azithromycin did not show increased risk ADRs based on RCTs (risk difference - 0.17 to 0.07). The incidence of QT prolonged was higher in the medium-dosage group (10-30 mg/kg/day) than that of low-dosage group (≤ 10 mg/kg/day) (82.0% vs 1.2%). CONCLUSION: The safety of azithromycin as MDA needs further evaluation. The most common ADRs are diarrhea and vomiting. The risk of the most serious uncommon ADRs (cardiac-prolonged QT and IHPS) is unknown.

Respiratory problems owing to severe metabolic alkalosis in infants presenting with hypertrophic pyloric stenosis.

OBJECTIVE: Uncorrected metabolic alkalosis in infantile hypertrophic pyloric stenosis (IHPS) could lead to perioperative apnea. However, the precise incidence of preoperative respiratory problems and the association with metabolic alkalosis are unknown. Therefore, we aimed to determine the incidence of preoperative respiratory problems in IHPS and to assess the association with metabolic alkalosis. METHODS: We retrospectively reviewed all patients diagnosed with IHPS during 2007-2017. Respiratory problems were classified as present or absent. With multivariate logistic regression we analyzed the association between bicarbonate and respiratory problems, corrected for gestational age and birth weight. RESULTS: We included 459 infants, of whom 23 developed preoperative respiratory problems (5.0%). Infants with preoperative respiratory problems were more often female (43.5% vs. 13.3% p = 0.001) and had significantly higher median serum levels of bicarbonate (32.0 mmol/L vs. 30.0 mmol/L), base excess (6.5 mmol/L vs. 5.3 mmol/L) and pCO2 (6.4 kPa vs. 5.9 kPa), compared to infants without respiratory problems. Multivariate analysis of serum bicarbonate and presence of respiratory problems showed an OR of 2.18 per 10 mmol/L (95% CI 1.21-4.71) (p = 0.009). The optimal bicarbonate cutoff point was 25.7 mmol/L (sensitivity 100%, specificity 13.4%). CONCLUSION: IHPS with metabolic alkalosis potentially results in preoperative respiratory problems. A lower bicarbonate target before surgery might be recommended and respiratory monitoring should be considered. LEVEL OF EVIDENCE: Level IV.

Perioperative apnea in infants with hypertrophic pyloric stenosis: A systematic review.

BACKGROUND: Infantile hypertrophic pyloric stenosis (IHPS) leads to excessive vomiting and metabolic alkalosis, which may subsequently cause apnea. Although it is generally assumed that metabolic derangements should be corrected prior to surgery to prevent apnea, the exact incidence of perioperative apneas in infants with IHPS and the association with metabolic alkalosis are unknown. We performed this systematic review to assess the incidence of apnea in infants with IHPS and to verify the possible association between apnea and metabolic alkalosis. METHODS: We searched MEDLINE, Embase, and Cochrane library to identify studies regarding infants with metabolic alkalosis, respiratory problems, and hypertrophic pyloric stenosis. We conducted a descriptive synthesis of the findings of the included studies. RESULTS: Thirteen studies were included for analysis. Six studies described preoperative apnea, three studies described postoperative apnea, and four studies described both. All studies were of low quality or had other research questions. We found an incidence of 27% of preoperative and 0.2%-16% of postoperative apnea, respectively. None of the studies examined the association between apnea and metabolic alkalosis in infants with IHPS. CONCLUSIONS: Infants with IHPS may have a risk to develop perioperative apnea. However, the incidence rates should be interpreted with caution because of the low quality and quantity of the studies. Therefore, further studies are required to determine the incidence of perioperative apnea in infants with IHPS. The precise underlying mechanism of apnea in these infants is still unknown, and the role of metabolic alkalosis should be further evaluated.

Does Maternal Omega 3 Supplementation Protect Against Infantile Hypertrophic Pyloric Stenosis?

OBJECTIVES: Infantile hypertrophic pyloric stenosis (IHPS) is potentially life threatening. The etiology of IHPS remains unknown and many risk factors have been reported. We aimed to assess the prevalence of known risk factors and investigate maternal nutrition and habits as possible additional risk factors for IHPS. METHODS: This case-control study includes mothers of infants diagnosed with IHPS and control mothers of infants, age 2 to 11 months, hospitalized in the pediatric department due to other conditions. Cases of IHPS were identified by review of all infants diagnosed with IHPS and operated upon in 2010 to 2016 at 2 major hospitals in central Israel. Data regarding potential risk factors were collected via questionnaires in both study groups. RESULTS: Sixty-six cases and 67 controls were included in the study. Maternal omega 3 supplement consumption during pregnancy was significantly less common among cases of IHPS as compared with controls (P = 0.031). Consumption of omega 3 supplement was defined as consumption of at least 1 to 2 per week during the pregnancy period. Following adjustment for known risk factors, including male sex and maternal smoking, maternal omega 3 supplement consumption remained associated with a significantly lower risk of developing IHPS (odds ratio = 0.303, 95% confidence interval 0.111-0.828, P = 0.02). CONCLUSIONS: Maternal omega 3 supplement consumption during pregnancy was associated with a significantly reduced risk of IHPS. Further studies are needed to support these results and investigate possible mechanisms of the effect of omega 3.

Low socioeconomic status and formula feeding directly correlate with increased incidence of hypertrophic pyloric stenosis.

PURPOSE: The purpose of this analysis was to determine if a correlation exists between socioeconomic status (SES) and pyloric stenosis (PS) as well as between PS and feeding method. METHODS: Data was collected retrospectively from the electronic medical record. Patients were included if they resided in a county in Illinois where our institution maintains >10% visit share, were < 1 year in age, and received a pyloromyotomy from January 2011 to May 2018. Patient addresses were geocoded and merged with county and tract-level census data. A control group was matched on gender, race, tract level, median household income (MHI), and age. Feeding method for each group was collected. Univariate analysis and multivariate analyses were employed. RESULTS: SES was explored using MHI. After controlling for gender, age, race, and institution adjusted tract size, the association between MHI and pyloromyotomy remained significant. As MHI decreased, the odds of having a PS case increased. Additionally, the PS incidence rate increased as MHI decreased. Patients who were exclusively formula fed were more likely to have PS. CONCLUSION: Pyloric stenosis had a direct correlation with SES as defined by MHI. As MHI decreased, the rates of PS increased. In addition, breastfeeding was protective, independent of MHI. TYPE OF STUDY: Prognosis study. LEVEL OF EVIDENCE: Level II.

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.

Infantile hypertrophic pyloric stenosis: profile, management and outcome of patients admitted to a tertiary hospital in Bloemfontein, South Africa.

BACKGROUND: Infantile hypertrophic pyloric stenosis (IHPS) is the thickening of both muscle layers of the pylorus and is most commonly found in first-born males. It usually presents with projectile, non-bilious vomiting. Late presentation leads to severe dehydration and malnutrition with deranged serum-electrolytes and acid-base imbalance delaying treatment and prolonging hospital stay. This study aims to evaluate the profile, management and outcome of IHPS at a tertiary hospital in Bloemfontein, South Africa. METHOD: The study was a retrospective, descriptive record review including all patients with IHPS admitted to Universitas Hospital from January 2008 to February 2016. Of the 22 patients admitted, files for 19 patients were available for inclusion. RESULTS: Sixteen (84.2%) of the 19 patients were male. Of the 11 patients with available birth order, two were first-, two second-, six third- and one fourth-born. The patients' ages ranged from 27 to 194 days (median 51 days). The most common symptoms were projectile vomiting (78.9%) and poor weight gain (68.4%). Six patients had no ultrasound done, and 17 patients underwent a Ramstedt-pyloromyotomy. Eight patients received atropine as part of their initial management. The duration of symptoms ranged from 1 to 58 days (median 14 days). There was no reported mortality. The length of stay ranged from 2 to 60 days (median 7 days). CONCLUSION: The gender distribution and age at presentation were in keeping with the literature but not the birth order. The delay before surgery emphasises the poor general health and deranged biochemical state the patients present at the hospital.

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.

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.

The incidence of infantile hypertrophic pyloric stenosis and its association with folic acid supplementation during pregnancy: A nested case-control study.

BACKGROUND AND RATIONALE: Several studies have suggested that the incidence of infantile hypertrophic pyloric stenosis (IHPS) has decreased in recent decades. This decrement is controversial and not fully explained. Concurrently, there has been a major increase in folic acid consumption by pregnant women to prevent neural tube defects. We aimed to describe IHPS incidence in Israel in recent years and to assess its potential association with folic acid consumption. METHODS: Using the electronic medical database of a 2.1 million member health organization in Israel, we identified all cases (n = 1899) of IHPS occurring between 1999 and 2015. Cases were individually matched with up to 5 controls (n = 7350) by birth date, sex, and region. Odds ratios and 95% confidence intervals by tertiles of cumulative dose of supplemented folic acid between three months prior to pregnancy and up to birth of index child were calculated using conditional logistic regression. RESULTS: During the study period IHPS incidence declined from 4.3 in 1999 to 2.1 per 1000 live births in 2015(p < 0.0001). No significant (p = 0.81) association was observed between folic acid intake during pregnancy and risk of IHPS incidence. Preterm birth and infant's use of macrolides during first 3 postnatal months were significantly (p < 0.01) associated with increased risk of IHPS. CONCLUSIONS: Similar to other countries, IHPS incidence in Israel has decreased in recent years. The decrement cannot be explained by increased use of folic acid. TYPE OF STUDY: Case Control Study. LEVEL OF EVIDENCE: Level III. SUMMARY: Using linkage to a large electronic patient database, this study investigated the association between the decrease in infantile hypertrophic pyloric stenosis and maternal exposure to folic acid during pregnancy.

Prevalence and descriptive epidemiology of infantile hypertrophic pyloric stenosis in the United States: A multistate, population-based retrospective study, 1999-2010.

BACKGROUND: Antecedents for infantile hypertrophic pyloric stenosis (IHPS) vary across studies; therefore, we conducted a multistate, population-based retrospective study of the prevalence and descriptive epidemiology of IHPS in the United States (US). METHODS: Data for IHPS cases (n = 29,554) delivered from 1999-2010 and enumerated from 11 US population-based birth defect surveillance programs, along with data for live births (n = 14,707,418) delivered within the same birth period and jurisdictions, were analyzed using Poisson regression to estimate IHPS prevalence per 10,000 live births. Additional data on deliveries from 1999-2005 from seven of these programs were analyzed using multivariable logistic regression to estimate adjusted prevalence ratios (aPR)s and 95% confidence intervals (CI)s for selected infant and parental characteristics. RESULTS: Overall, IHPS prevalence from 1999-2010 was 20.09 (95% CI = 19.87, 20.32) per 10,000 live births, with statistically significant increases from 2003-2006 and decreases from 2007-2010. Compared to their respective referents, aPRs were higher in magnitude for males, preterm births, and multiple births, but lower for birth weights <2,500 g. The aPRs for all cases increased with decreasing parental age, maternal education, and maternal parity, but decreased for parental race/ethnicity other than non-Hispanic White. Estimates restricted to isolated cases or stratified by infant sex were similar to those for all cases. CONCLUSIONS: This study covers one of the largest samples and longest temporal period examined for IHPS in the US. Similar to findings reported in Europe, estimates suggest that IHPS prevalence has decreased recently in the US. Additional analyses supported associations with several infant and parental characteristics.

Infantile Hypertrophic Pyloric Stenosis: An Epidemiological Review.

Infantile hypertrophic pyloric stenosis (IHPS) is the most common gastrointestinal disease among infants. IHPS occurs as an isolated condition or together with other congenital anomalies. Association with genetic and environmental factors, bottle feeding, younger maternal age, maternal smoking, and erythromycin administration in the first two weeks of life has been shown. Familial aggregation has been described and a family history is seen in 47.9 percent of siblings. Infants typically present with projectile vomiting associated with symptoms of failure to thrive. An olive-like mass palpable in the right upper abdominal quadrant is being reported less frequently because of earlier diagnosis by ultrasound. IHPS is generally corrected through laparoscopic pyloromyotomy. Endoscopic pyloric balloon dilation is a novel alternative. Further studies on different populations, the general population, and familial segregation to determine the prevalence, influence, and mode of familial aggregation and correlation with environmental factors are needed to determine the etiology of IHPS.