The epidemiology of infantile hypertrophic pyloric stenosis in a Danish population, 1950-84

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.

Open versus laparoscopic pyloromyotomy for pyloric stenosis

BACKGROUND

Infantile hypertrophic pyloric stenosis (IHPS) is a disorder of young children (aged one year or less) and can be treated by laparoscopic (LP) or open (OP) longitudinal myotomy of the pylorus. Since the first description in 1990, LP is being performed more often worldwide.

OBJECTIVES

To compare the efficacy and safety of open versus laparoscopic pyloromyotomy for IHPS.

SEARCH METHODS

We conducted a literature search on 04 February 2021 to identify all randomised controlled trials (RCTs), without any language restrictions. We searched the following electronic databases: MEDLINE (1990 to February 2021), Embase (1990 to February 2021), and the Cochrane Central Register of Controlled Trials (CENTRAL). We also searched the Internet using the Google Search engine (www.google.com) and Google Scholar (scholar.google.com) to identify grey literature not indexed in databases.

SELECTION CRITERIA

We included RCTs and quasi-randomised trials comparing LP with OP for hypertrophic pyloric stenosis.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened references and extracted data from trial reports. Where outcomes or study details were not reported, we requested missing data from the corresponding authors of the primary RCTs. We used a random-effects model to calculate risk ratios (RRs) for binary outcomes, and mean differences (MDs) for continuous outcomes. Two review authors independently assessed risks of bias. We used GRADE to assess the certainty of the evidence for all outcomes.

MAIN RESULTS

The electronic database search resulted in a total of 434 records. After de-duplication, we screened 410 independent publications, and ultimately included seven RCTs (reported in 8 reports) in quantitative analysis. The seven included RCTs enrolled 720 participants (357 with open pyloromyotomy and 363 with laparoscopic pyloromyotomy). One study was a multi-country trial, three were carried out in the USA, and one study each was carried out in France, Japan, and Bangladesh. The evidence suggests that LP may result in a small increase in mucosal perforation compared with OP (RR 1.60, 95% CI 0.49 to 5.26; 7 studies, 720 participants; low-certainty evidence). LP may result in up to 5 extra instances of mucosal perforation per 1,000 participants; however, the confidence interval ranges from 4 fewer to 44 more per 1,000 participants. Four RCTs with 502 participants reported on incomplete pyloromyotomy. They indicate that LP may increase the risk of incomplete pyloromyotomy compared with OP, but the confidence interval crosses the line of no effect (RR 7.37, 95% CI 0.92 to 59.11; 4 studies, 502 participants; low-certainty evidence). In the LP groups, 6 cases of incomplete pyloromyotomy were reported in 247 participants while no cases of incomplete pyloromyotomy were reported in the OP groups (from 255 participants). All included studies (720 participants) reported on postoperative wound infections or abscess formations. The evidence is very uncertain about the effect of LP on postoperative wound infection or abscess formation compared with OP (RR 0.59, 95% CI 0.24 to 1.45; 7 studies, 720 participants; very low-certainty evidence). The evidence is also very uncertain about the effect of LP on postoperative incisional hernia compared with OP (RR 1.01, 95% CI 0.11 to 9.53; 4 studies, 382 participants; very low-certainty evidence). Length of hospital stay was assessed by five RCTs, including 562 participants. The evidence is very uncertain about the effect of LP compared to OP (mean difference -3.01 hours, 95% CI -8.39 to 2.37 hours; very low-certainty evidence). Time to full feeds was assessed by six studies, including 622 participants. The evidence is very uncertain about the effect of LP on time to full feeds compared with OP (mean difference -5.86 hours, 95% CI -15.95 to 4.24 hours; very low-certainty evidence). The evidence is also very uncertain about the effect of LP on operating time compared with OP (mean difference 0.53 minutes, 95% CI -3.53 to 4.59 minutes; 6 studies, 622 participants; very low-certainty evidence).

AUTHORS' CONCLUSIONS

Laparoscopic pyloromyotomy may result in a small increase in mucosal perforation when compared with open pyloromyotomy for IHPS. There may be an increased risk of incomplete pyloromyotomy following LP compared with OP, but the effect estimate is imprecise and includes the possibility of no difference. We do not know about the effect of LP compared with OP on the need for re-operation, postoperative wound infections or abscess formation, postoperative haematoma or seroma formation, incisional hernia occurrence, length of postoperative stay, time to full feeds, or operating time because the certainty of the evidence was very low for these outcomes. We downgraded the certainty of the evidence for most outcomes due to limitations in the study design (most outcomes were susceptible to detection bias) and imprecision. There is limited evidence available comparing LP with OP for IHPS. The included studies did not provide sufficient information to determine the effect of training, experience, or surgeon preferences on the outcomes assessed.

Sonography and Test-Feeding in the Diagnosis of Infantile Hypertrophic Pyloric Stenosis

Objective:

To determine the use of sonography and test-feeding in the diagnosis of infantile hypertrophic pyloric stenosis (IHPS).

Methodology:

A total of 79 infants from 2 weeks up to 12 weeks presenting with clinical signs (projectile vomiting) of IHPS were included in the study while sent to sonography. The study duration was February 2014 to December 2019.

Results:

The mean age of patients was 5.18 ± 2.69 weeks ranging from 1 to 12 weeks. Male gender was predominant with 62 (78.5%) cases. Of the total 79 cases, 36 (54.6%) were suggested as positive cases of IHPS and 43 (54.4%) were as normal with sonography. Most of the cases of IHPS (23; 29.1%) were observed in firstborn babies. Mean pyloric length in normal and IHPS was 12.69 ± 0.87 and 20.78 ± 2.28 mm, respectively, and mean pyloric muscle thickness in the normal and IHPS was 2.24 ± 0.36 and 5.27 ± 0.82 mm, respectively, while mean pyloric diameter in normal and IHPS was 12.69 ±0.87 and 15.01± 2.52 mm, respectively.

Conclusion:

The reliability of sonographic findings was better than test-feeding in the diagnosis of IHPS. Male infants, in this cohort, were five times more susceptible to develop IHPS, compared with females.

Prematurity Affects Age of Presentation of Pyloric Stenosis

Term infants with hypertrophic pyloric stenosis (HPS) typically present between 4 and 6 weeks. There is limited consensus, however, regarding age of presentation of premature infants. We aim to determine if there is an association between the degree of prematurity and chronological age of presentation of HPS. A total of 2988 infants who had undergone a pyloromyotomy for HPS were identified from the 2012 and 2013 NSQIP-P Participant Use Files. Two hundred seventeen infants (7.3%) were born prematurely. A greater degree of prematurity was associated with an older chronological age of presentation ( P < .0001). Prematurity was significantly associated with an increase in overall postoperative morbidity, reintubation, readmission, and postoperative length of stay. When clinicians evaluate an infant with nonbilious emesis with a history of prematurity, they should consider pyloric stenosis if the calculated postconceptional age is between 44 and 50 weeks. When counseling families of premature infants, surgeons should discuss the increased incidence of postpyloromyotomy morbidity.

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.

Association of prematurity with the development of infantile hypertrophic pyloric stenosis

BACKGROUND

Infantile hypertrophic pyloric stenosis (IHPS) has several known risk factors. The association between prematurity and IHPS and the timeline of presentation are poorly defined. Our aim was to evaluate the associations between IHPS and prematurity.

METHODS

We performed a retrospective cohort study of 1,074,236 children born between June 2001 and April 2012 in the US Military Health System. IHPS cases and gestational ages (GA) were identified using billing codes. Additional risk factors for IHPS were controlled for in a multivariable logistic regression model.

RESULTS

The incidence of IHPS was 2.99 per 1,000 in preterm infants and 2.25 per 1,000 in full term (relative risk (RR) = 1.33, 95% confidence interval (CI) 1.16-1.54). The adjusted odds ratio for prematurity was 1.26 (95% CI 1.08-1.46). The median (interquartile range (IQR)) chronological age at presentation was 40 d (30-56) in preterm infants vs. 33 d (26-45) in full term (P < 0.001). Median postmenstrual age at presentation was 42 wk in preterm infants (40-42) vs. 45 wk (44-46) in full term (P < 0.001).

CONCLUSION

Prematurity is associated with IHPS. Premature infants develop IHPS at a later chronological age, but earlier postmenstrual age, than term infants. Providers should have an increased concern for IHPS development in premature infants.

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.

Maternal and pregnancy characteristics and risk of infantile hypertrophic pyloric stenosis

BACKGROUND/PURPOSE

The incidence of infantile hypertrophic pyloric stenosis (IHPS) in Sweden decreased dramatically during the 1990s. The aim of the study was to examine IHPS risk factors and the possible change in them as the incidence declined.

METHODS

This is a case-control study including 3608 surgically treated IHPS cases and 17588 matched controls during 1973-2008. Cases were identified in the Swedish National Patient Register and data on possible risk factors were collected from the Swedish Medical Birth Register. The association between study variables and IHPS was analyzed using conditional logistic regression for the whole study period and separately for periods with high and low IHPS incidences.

RESULTS

Prematurity (OR, 2.54; 95% CI, 2.06-3.14), caesarean delivery (OR, 1.67; 95% CI, 1.51-1.86), maternal smoking (OR, 1.82; 95% CI, 1.53-2.16), and young maternal age (< 20yrs) (OR, 1.42; 95% CI, 1.17-1.73) were associated with an increased IHPS risk. Birth order 2 (OR, 0.78; 95% CI, 0.71-0.85) or more was associated with a lower IHPS risk. ORs for smoking increased at low incidence rate.

CONCLUSION

We report caesarean section, prematurity, primiparity, young maternal age, and smoking as significant IHPS risk factors. The impact of smoking was higher during periods with a low incidence.

The ins and outs of pyloromyotomy: what we have learned in 35 years

PURPOSE/BACKGROUND

The aim of the study is to evaluate a large series of infantile hypertrophic pyloric stenosis (IHPS) patients treated by one pediatric surgeon focusing on their diagnostic difficulties and complications.

METHODS

From July 1969 to December 2003 (inclusive), the charts of 791 infants with IHPS were retrospectively reviewed.

RESULTS

There were 647 (82%) males and 144 (18%) females; mean age was 38 days, median 51 (range 7 days-10 months). When ultrasonography (US) was routinely used (1990), the age at diagnosis decreased to <40 days. The mean weight before and after routine US was 3.2 kg, median 3 (range 1.5-6). Twenty-five (3.1%) were premature at diagnosis, mean age 49 days, median 56, (range 1-3 months) and mean weight 2.5 kg, median 2.3 (range 1.5-3.2). Eighty-one (10%) had a positive family history. Forty-four (5%) were non-Caucasians. Seventy-five (9 %) had other medical conditions, anomalies and/or associated findings. Sixty (7%) patients had abnormal preoperative electrolytes. Ten (1.2%) pylorics occurred after newborn operations. Of the entire total (791) who were treated, there were 13 (1.7%) not operated on. All operations were done open initially through one of two right upper quadrant incisions, and then through an upper midline incision under general endotracheal anesthesia; 14 (1.7 %) had concomitant procedures. Prophylactic antibiotics (from 1982) decreased the wound infection rate to 3.9%. There were a total of 87 (10%) complications which included 9 (1.1%) intraoperative, (including mistaken diagnoses) 78 (9%) postoperative: 59 (2%) early (<1 month) and 19 (2.4%) late (>1 month). The 13 (1.6%) postoperative transfers (12 from non-pediatric surgeons) had 16 (18%) complications (including 1 death); five (33%) requiring reoperation (4 incomplete, 1 perforation). There were two deaths.

CONCLUSIONS

IHPS should be considered in any vomiting infant. US allows earlier diagnosis. Serious complications are uncommon and avoidable, but recognizable and easily corrected. Higher surgeon volume of pyloromyotomies (>14 per year) is associated with fewer complications.

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.

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.

The involvement of nitric oxide synthase neurons in enteric neuropathies

Nitric oxide (NO), produced by the neural nitric oxide synthase enzyme (nNOS) is a transmitter of inhibitory neurons supplying the muscle of the gastrointestinal tract. Transmission from these neurons is necessary for sphincter relaxation that allows the passage of gut contents, and also for relaxation of muscle during propulsive activity in the colon. There are deficiencies of transmission from NOS neurons to the lower esophageal sphincter in esophageal achalasia, to the pyloric sphincter in hypertrophic pyloric stenosis and to the internal anal sphincter in colonic achalasia. Deficits in NOS neurons are observed in two disorders in which colonic propulsion fails, Hirschsprung's disease and Chagas' disease. In addition, damage to NOS neurons occurs when there is stress to cells, in diabetes, resulting in gastroparesis, and following ischemia and reperfusion. A number of factors may contribute to the propensity of NOS neurons to be involved in enteric neuropathies. One of these is the failure of the neurons to maintain Ca(2+) homeostasis. In neurons in general, stress can increase cytoplasmic Ca(2+), causing a Ca(2+) toxicity. NOS neurons face the additional problem that NOS is activated by Ca(2+). This is hypothesized to produce an excess of NO, whose free radical properties can cause cell damage, which is exacerbated by peroxynitrite formed when NO reacts with oxygen free radicals.

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.

Infantile hypertrophic pyloric stenosis before 3 weeks of age in infants and preterm babies

BACKGROUND

Most infantile hypertrophic pyloric stenosis (IHPS) cases are diagnosed between 3 and 12 weeks after birth. Few data exist regarding Asian infants with IHPS who are younger than 3 weeks or are preterm. The goal of this study is to identify unusual clinical manifestations, clinical course, duration of hospital stay, and complications of Asian infants with IHPS who are preterm or younger than 3 weeks of age.

METHODS

From 1991 to 2004, all IHPS patients admitted to three tertiary centers in southern Taiwan were enrolled. The clinical manifestations, duration of hospital stay and complications were further compared between the IHPS patients diagnosed before and after 3 weeks; preterm and term infants.

RESULTS

A total of 214 patients were enrolled into the study; the mean age of diagnosis was 40 days of age; the average duration of hospital stay was 6.27 days. Eighteen (8.41%) patients were diagnosed before 3 weeks of age. A significantly shorter timeframe of diagnosis, a higher rate of jaundice, a lower daily body weight gain and longer duration of hospital stay were noted in the IHPS group prior to 3 weeks compared with those in IHPS group after 3 weeks. Eighteen were preterm infants. A significantly older age of symptom onset, a lower body weight at admission, more cases diagnosed by barium meal study and higher postoperative complication rates were noted in the preterm group versus full-term infants with IHPS.

CONCLUSIONS

The IHPS cases diagnosed before 3 weeks of age had longer duration of hospital stay. Preterm infants with IHPS had more postoperative complications.

Epidemiological features of infantile hypertrophic pyloric stenosis in Taiwan: a national study 1996-2004

BACKGROUND AND AIM

The incidence of infantile hypertrophic pyloric stenosis (IHPS) varies among different countries and is supposed to be lower in Asian countries than in Western countries. However, the incidence of IHPS in Taiwan has not been well investigated.

METHODS

The National Health Insurance (NHI) program was implemented in Taiwan in 1995 and covers most of the population (>99%). We used the NHI database to investigate the epidemiological features of IHPS in Taiwan and to compare the data with that of other countries.

RESULTS

We identified 962 new IHPS cases during the period from 1996 to 2004. The overall incidence of IHPS was 0.39 (0.34-0.50) cases per 1000 live births. The estimation was 0.39-0.59 per 1000 live births after adjustment for the misdiagnosis rate. The peak incidence (0.58 per 1000 live births) occurred in winter in 1999. Rates were consistently higher in male subjects. The 1-year survival rate was not significantly different in the patients receiving pyloromyotomy in medical centers, regional hospitals, and district hospitals (P=0.389).

CONCLUSIONS

Taiwan had the second lowest incidence of IHPS reported in the medical literature. IHPS patients can be successfully treated in district and general hospitals with good prognosis.

Infantile hypertrophic pyloric stenosis: a comparative study of incidence and other epidemiological characteristics in seven European regions

OBJECTIVE

The objective of this study was to present epidemiologic data on infantile hypertrophic pyloric stenosis (IHPS) from seven well-defined European regions, and to compare incidence and changes in incidence over time between these regions.

METHODS

This was a population-based study using data from registries of congenital malformations (EUROCAT) for a period of more than two decades (1980-2002).

RESULTS

A total of 2534 infants were diagnosed with IHPS during the study period, giving an overall incidence of IHPS of 2.0 per 1000 live births (LB), ranging from 0.86 per 1000 LB to 3.96 per 1000 LB in the seven regions. A significant decrease in incidence was observed in two regions and a significant increase in incidence was observed in two other regions. Young maternal age (<20 years) significantly increased the risk of IHPS by 29% (adjusted by region; p < 0.01), and at maternal age of 30 years and older the risk decreased significantly (p < 0.01).

CONCLUSIONS

There were significant differences in the incidence of IHPS in the seven European populations. No uniform pattern of change in incidence was observed as the populations also differed in relation to trend over time with both significant increases and decreases over time. There is evidence that young maternal age is a risk factor for IHPS.

Genome-wide high-density SNP-based linkage analysis of infantile hypertrophic pyloric stenosis identifies loci on chromosomes 11q14-q22 and Xq23

Infantile hypertrophic pyloric stenosis (IHPS) has an incidence of 1-8 per 1000 live births and is inherited as a complex sex-modified multifactorial trait with a striking male preponderance. Syndromic and monogenic forms exist, and two loci have been identified. Infants present with vomiting due to gastric-outlet obstruction caused by hypertrophy of the smooth muscle of the pylorus. A genome-wide SNP-based high-density linkage scan was carried out on 81 IHPS pedigrees. Nonparametric and parametric linkage analysis identified loci on chromosomes 11q14-q22 (Z(max) = 3.9, p < 0.0001; HLOD(max) = 3.4, alpha = 0.34) and Xq23 (Z(max) = 4.3, p < 0.00001; HLOD(max) = 4.8, alpha = 0.56). The two linked chromosomal regions each harbor functional candidate genes that are members of the canonical transient receptor potential (TRPC) family of ion channels and have a potential role in smooth-muscle control and hypertrophy.

The continuing enigma of pyloric stenosis of infancy: a review

Striking features of the descriptive epidemiology of pyloric stenosis of infancy have been identified but until recently have not suggested any useful etiologic lead. The disease first received serious attention approximately 100 years ago and has since occurred throughout the Western world at a rate between 2 and 5 per thousand live births; it appears to be uncommon elsewhere. Its age distribution is essentially limited to the period between the third and eighth weeks after birth. It is 4 to 5 times more common in boys than girls. It is less common in blacks than whites in the United States and less common among Asians than whites in the United States and elsewhere. Its incidence is highest in first-born infants. Evidence on a role for maternal age is not consistent. The disease re-occurs in families with sufficient frequency to incite the interest of geneticists, although no genetic model yet proposed offers a better basis for counseling than do the empiric observations on which it is based. Monozygous twins are concordant for the disease not much more frequently than are dizygous twins, and indeed not a great deal more often than nontwin siblings, which should prompt a search for environmental explanations of the disease's familial nature. Sharp declines in the incidence of the disease in Denmark and Sweden during the 1990s led to the hypothesis that infants sleeping in the prone position-a practice discouraged with some success by Scandinavian campaigns to reduce the frequency of sudden infant death syndrome (SIDS)-may also be at increased risk of pyloric stenosis. If supported, this hypothesis may offer the first-ever possibility of reducing the frequency of this disease, as well as SIDS. If the hypothesis is not supported, the recent declines in the disease in Denmark and Sweden add another facet to its enigmatic nature.

Preterm birth, low birth weight, and risk for esophageal adenocarcinoma

BACKGROUND & AIMS

Gastroesophageal reflux is common among preterm infants and those who are small for gestational age, and it is a strong risk factor for adenocarcinoma of the esophagus.

METHODS

In a cohort of 3364 individuals born preterm and/or small for gestational age between 1925 and 1949, we assessed the long-term risk for esophageal cancer.

RESULTS

The standardized incidence rate ratio for esophageal adenocarcinoma was increased more than 7-fold in the cohort (standardized incidence rate ratio, 7.27; 95% confidence interval, 1.98-18.62), and a birth weight <2000 g was associated with a more than 11-fold increase in risk (standardized incidence rate ratio, 11.5; 95% confidence interval, 1.39-41.5).

CONCLUSIONS

The associations may be spurious, but if not, they may be explained by increased gastroesophageal reflux during infancy among infants born preterm and/or small for gestational age.

Single-nucleotide promoter polymorphism alters transcription of neuronal nitric oxide synthase exon 1c in infantile hypertrophic pyloric stenosis

Infantile hypertrophic pyloric stenosis (IHPS), characterized by enlarged pyloric musculature and gastric-outlet obstruction, is associated with altered expression of neuronal nitric oxide synthase (nNOS). Here we have studied molecular mechanisms by which nNOS gene expression is altered in pyloric tissues of 16 infants with IHPS and 9 controls. A significant decreased expression of total nNOS mRNA was found by quantitative RT-PCR in IHPS after normalization against GAPDH, which predominantly affected exon 1c with a reduction of 88% compared with controls (P < 0.001). After normalization against the neuronal-specific gene PGP9.5, expression of exon 1c was still decreased (P < 0.001), whereas expression of exon 1f was increased significantly (P = 0.001), indicating a compensatory up-regulation of this nNOS mRNA variant. DNA samples of 16 IHPS patients and 81 controls were analyzed for nNOS exon 1c promoter mutations and single-nucleotide polymorphism (SNP). Sequencing of the 5'-flanking region of exon 1c revealed mutations in 3 of 16 IHPS tissues, whereas 81 controls showed the wild-type sequence exclusively. Carriers of the A allele of a previously uncharacterized nNOS exon 1c promoter SNP (-84G --> A) had increased risk for development of IHPS (odds ratio, 8.0; 95% confidence interval, 2.5-25.6). Reporter gene assays revealed an unchanged promoter activity for mutations but a approximately 30% decrease for the -84A SNP (P < 0.001). In summary, our findings indicate that genetic alterations in the nNOS exon 1c regulatory region influence expression of the nNOS gene and may contribute to the pathogenesis of IHPS.

The epidemiology of infantile hypertrophic pyloric stenosis in Sweden 1987-96

AIMS

To find out whether the incidence of infantile hypertrophic pyloric stenosis (IHPS) has changed over the past decade, and if so, to investigate possible contributory factors.

METHODS

All infants undergoing pyloromyotomy for IHPS in Sweden between 1987 and 1996 were studied. Using the national patient registers the yearly incidence was determined and evaluated in relation to sex, latitude, urbanisation, and type of surroundings by use of a Poisson model.

RESULTS

There was a substantial decline from 2.7/1000 to 0.85/1000 over the time period. The incidence in the south was almost three times greater than in the north.

CONCLUSION

The declining incidence and geographical difference suggest that environmental factors are of importance in this disorder.

The epidemiology of infantile hypertrophic pyloric stenosis in Greater Glasgow area, 1980-96

The annual incidence of infantile hypertrophic pyloric stenosis (IHPS) in Greater Glasgow area from 1980 to 1996 was calculated. An increasing incidence was observed between 1980 and 1988 but not thereafter. There is a suggestion that environmental factors may play a role in the aetiology of this condition.

Parallel incidences of sudden infant death syndrome and infantile hypertrophic pyloric stenosis: a common cause?

OBJECTIVE

To determine whether there was a correlation between the incidence of infantile hypertrophic pyloric stenosis (IHPS) and the incidence of sudden infant death syndrome (SIDS) during the period 1970 to 1997 and to discuss different causative factors that could be influencing the changing trend in incidence.

METHODS

We compared the incidence of IHPS in the Stockholm Health Care Region with the incidence of SIDS in Sweden each year between 1970 and 1997. First, the relation was assessed by calculation of a correlation coefficient; second, the relative linear decrease was estimated for the time period 1990 to 1997.

RESULTS

The incidence of IHPS increased steadily during the 1970s, from 0.5 per 1000 live births in 1970 to 2.7 in 1979. During the 1980s, the average incidence was 2.8. During the 1990s, there was a significant decrease in the number of IHPS cases in Stockholm. The incidence rate of IHPS parallels the incidence of SIDS during the study period (r = 0.58). The incidence of SIDS dropped after the risk-reduction campaign in the beginning of the 1990s, which recommended that infants sleep on their back. We could not identify any other changes of behavioral risk factors in early exposures that could explain the temporal trends.

CONCLUSIONS

The statistical findings suggest that IHPS and SIDS have causative factors in common. We suggest that prone sleeping is one of those factors.

Is Helicobacter pylori a cause of infantile hypertrophic pyloric stenosis?

My hypothesis is that infantile hypertrophic pyloric stenosis (IHPS) is caused in some cases by Helicobacter pylori (HP) a bacterium commonly found in the human stomach. IHPS is an idiopathic condition of infancy. It occurs at about 5 weeks of age in 3 per 1000 newborns. Children with IHPS have structurally normal pylori at birth and do not resemble children with congenital anomalies. Some nonspecific evidence (temporal distribution, seasonality, familial clustering, leukocytic infiltrates, and increased risk with bottle feeding) are compatible with an infectious etiology. Some other epidemiologic features of IHPS, such as its strong male predominance, its racial and social class variation, and a possible drop in its incidence, are also features of HP infection. Clinical features of IHPS, such as vomiting, hematemesis, and esophagitis, are also consistent with HP. Finally, children with IHPS appear to be more likely to develop chronic conditions, such as peptic ulcers, now known to be caused by HP.

Distinct expression of splice variants of neuronal nitric oxide synthase in the human gastrointestinal tract

BACKGROUND & AIMS

Changes of neuronal nitric oxide synthase (nNOS) expression have been linked to several human gastrointestinal disorders such as achalasia, diabetic gastroparesis, and hypertrophic pyloric stenosis. They could be caused by differential transcriptional control or alternative splicing generating different nNOS proteins. The aims of this study were to characterize 5'-splice variants, promoter usage, and site-specific expression of nNOS in the human gastrointestinal tract.

METHODS

5'-Splice variants were characterized by immunoblotting, reverse-transcription polymerase chain reaction, 5'-rapid amplification of complementary DNA ends, and Southern blotting. Genomic analysis was performed by rapid amplification of genomic ends, followed by reporter gene assays.

RESULTS

Six different 5'-splice variants of nNOS-messenger RNA were identified showing specific expressions at various sites of the human gastrointestinal tract. Three variants encode for nNOSalpha, which has a specific N-terminal PDZ/GLGF domain and interaction sites for regulatory proteins. Two variants encode for nNOSbeta and 1 for nNOSgamma, which both lack the protein-binding domains of nNOSalpha. In addition to 2 known first exons, a novel first exon of human nNOS with a separate functionally active downstream promoter and multiple binding sites for transcription factors was identified and characterized.

CONCLUSIONS

Six 5'-mRNA splice variants of nNOS encoding 3 different nNOS proteins are expressed in the human gut. The differential expression of these proteins could be implicated in different biological functions.

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.

Infantile hypertrophic pyloric stenosis and hydronephrosis: is there an association?

Infantile hypertrophic pyloric stenosis is a common condition requiring surgical intervention during the first few weeks of life. The incidence of infantile hypertrophic pyloric stenosis ranges from 0.13 to 0.4% of live births in the United States, Britain and Scandinavia. Associated anomalies have been described in 6 to 33% of the cases in the central nervous system, gastrointestinal tract and heart. An association of infantile hypertrophic pyloric stenosis with urinary tract anomalies has not been previously documented. A review of 422 patients with infantile hypertrophic pyloric stenosis revealed urinary tract anomalies in 6 (10 renal units), including 4 renal units with vesicoureteral reflux and 9 with hydronephrosis. This incidence of 1.4% is greater than the 0.2% incidence expected in the general population. This 7-fold increase in urinary tract anomalies in patients with infantile hypertrophic pyloric stenosis suggests an association between the two and warrants further investigation. Serious consideration should be given to obtaining renal ultrasound examinations in patients with infantile hypertrophic pyloric stenosis.