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

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.

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.

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.

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.

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.

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.

Perinatal risk factors for infantile hypertrophic pyloric stenosis: A meta-analysis

BACKGROUND

Infantile hypertrophic pyloric stenosis (IHPS) is the most common surgical cause of nonbilious vomiting in infancy. The etiology of IHPS is not completely understood. Hence, we performed a meta-analysis to investigate the association between perinatal factors and IHPS onset.

METHODS

The MEDLINE, EMBASE, PubMed and Cochrane Library databases were searched for studies published in English before December 2016. The combined odd ratios (ORs) and 95% confidence intervals (CIs) were calculated using random-effects models.

RESULTS

Fifteen studies were included. Several perinatal factors, including first-born (OR 1.19, 95% CI: 1.07-1.33), cesarean section delivery (OR 1.63, 95% CI: 1.53-1.73), preterm birth (OR 1.37, 95% CI: 1.12-1.67), and bottle-feed (OR 2.46, 95% CI: 1.76-3.43), were significantly associated with the IHPS onset. Among these, bottle-feed was the most significantly risk factor for IHPS onset. Although few studies have evaluated the relationship between perinatal factors and IHPS, they have major limitations including retrospective collection of data on perinatal events and testing of multiple hypotheses without appropriate statistical corrections.

CONCLUSIONS

First-born, cesarean section delivery, preterm birth, and bottle-feed are associated with the development of IHPS. Well-designed future studies are needed to help understand the etiology of IHPS.

TYPE OF STUDY

Systematic reviews and meta-analyses.

LEVEL OF EVIDENCE

Level III.

Formula-feeding and hypertrophic pyloric stenosis: is there an association? A case-control study

BACKGROUND

The etiology of infantile hypertrophic pyloric stenosis (HPS) is not fully understood. The objective of this study was to determine whether formula-feeding is associated with increased incidence.

METHODS

This case-control study included HPS cases and controls admitted between 1992 and 2012. Demographic data including feeding method were collected from patient charts and analyzed.

RESULTS

We identified 882 HPS cases and 955 controls. The highest incidence of HPS presentation was in summer (P=0.0028). Infants with HPS were more likely to have been exclusively formula-fed, have a family history of HPS, and be male compared to infants in the control group (P<0.001); they were also more likely to live in rural areas, although not significantly so. After adjusting for family history, sex, place of residence, and season of presentation, exclusively formula-fed infants were 1.36 times more likely to develop HPS compared with exclusively breastfed infants (RR 1.36, 95% CI 1.18-1.57, P<0.005).

CONCLUSIONS

Formula-feeding is associated with significantly increased risk of HPS. Further investigation may help to determine the components of formula that simulate hypertrophy of the pylorus muscle, or the components of breast milk that are protective, as well as other influencing factors.

LEVEL OF EVIDENCE

3b.

A new technique for performing endoscopic pyloromyotomy by gastric submucosal tunnel dissection

AIM

To investigate the feasibility of a new endoscopic pyloromyotomy technique.

MATERIALS AND METHODS

Endoscopic pyloromyotomy through a gastric submucosal tunnel was performed in 6 pigs. At the greater curvature, 2 cm proximal to the pylorus, we incised the mucosa and dissected the submucosal tunnel up to the pyloric ring. The pyloric muscular ring was sectioned, and then the gastric mucosal incision was closed with metallic clips. The pigs were then euthanized and necropsies were performed.

RESULTS

Section of the pyloric ring was successful in all 6 pigs. Small perforations occurred in 2 of the pigs, and there was limited bleeding in 1 pig. Necropsy and histologic evaluation confirmed the pyloric section.

CONCLUSIONS

This technique is feasible, easy to perform, and maybe alternative to pyloroplasty in selected cases. Experimental comparative studies with other techniques still must be performed.

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.

Hospitalization of rural and urban infants during the first year of life

OBJECTIVES

To examine hospitalizations and length of stay (LOS) for infants aged <1 year in rural and urban counties, hypothesizing that infants living in rural counties experience significantly different hospital use compared with urban infants.

METHODS

Birth certificates for infants born in California hospitals between 1993 and 2005 and surviving to discharge were linked to hospital discharge records and death certificates during the first year of life, resulting in a study population of >6.4 million. Hospitalizations, cumulative LOS, readmission rates, and mortality were compared by using univariate and multivariable analysis for infants living in small rural, large rural, small urban, and large urban counties. Odds of hospitalization and cumulative LOS were also examined for common infant diagnoses.

RESULTS

Infants living in increasingly rural counties experienced decreasing rates of hospitalization and decreasing number of hospitalized days during the first year of life. Infants living in small rural counties experienced 370 hospital days per 1000 infants compared with 474 hospital days per 1000 infants living in large urban counties. In multivariable analysis, infants in large urban counties experienced increased odds of hospitalization (odds ratio: 1.20 [95% confidence interval: 1.06-1.36]) and increased hospitalized days (incidence risk ratio: 1.17 [95% confidence interval: 1.06-1.29]) compared with infants in small rural counties. For most common diagnoses, urban residence was associated with either increased odds of hospitalization or increased cumulative LOS.

CONCLUSIONS

Infants living in rural California counties experienced decreased hospital utilization, including decreased hospitalization and decreased LOS, compared with infants living in urban counties.

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.

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.

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.

Endoscopic pyloroplasty with full-thickness transgastric and transduodenal myotomy with sutured closure

BACKGROUND

Pyloroplasty with myotomy and sutured closure is a surgical treatment for gastric outlet obstruction. It has not been previously performed at flexible endoscopy.

OBJECTIVE

To develop and test a method for performing a sutured pyloroplasty at flexible endoscopy.

DESIGN

A Heinicke-Miculicz pyloroplasty was performed, forming a linear myotomy through the pylorus from the gastric side into the duodenal bulb. This was subsequently sutured transversely to increase the opening. The operation was performed in 3 nonsurvival studies in pigs. The safety and the efficacy was then studied in 7 animals followed for up to 4 weeks after the procedure.

SETTING

The studies were performed in experimental surgical units in Gothenburg, Sweden, and London, UK.

INTERVENTIONS

A linear needle-knife incision was made through the pylorus; full-thickness sutures, by using a new T-tag and polypropylene thread suturing system through a flexible gastroscope, were placed to close the incision transversely. In 2 pigs, the prepyloric bulge was excised before the pyloroplasty.

RESULTS

Pyloroplasty was readily accomplished at flexible endoscopy in the 3 nonsurvival studies. Six of 7 pigs that survived in this study for periods of 7 to 28 days, recovered well, without complications. One pig (with bulge removal) developed gastric retention. The pyloric opening was increased; it was then easy to enter the duodenum at follow-up endoscopy.

LIMITATIONS

This method has yet to be studied clinically.

CONCLUSIONS

Pyloroplasty with full-thickness pyloromyotomy and transverse closure of a linear myotomy was accomplished by using a simple flexible endosurgical technique to test a new flexible suturing system.

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.

A novel point mutation of the androgen receptor (F804L) in an Egyptian newborn with complete androgen insensitivity associated with congenital glaucoma and hypertrophic pyloric stenosis

Androgen-insensitivity syndrome (AIS) is a major cause of male pseudohermaphroditism (MPH). Although AIS is usually reported as a monogenic disease resulting from androgen receptor (AR) mutations, on rare occasions it has been observed as part of a multiple congenital anomaly syndrome. We report here a patient who was the first newborn girl of an unrelated couple. Shortly after birth, the diagnoses of congenital glaucoma and pyloric stenosis were made. A detailed history of the father's family revealed that nine members presented glaucoma before 40 years of age. Clinical and ultrasound evaluation showed two inguinal testes, with female external genitalia and no Mullerian derivatives. The patient had a 46,XY karyotype, good testicular response to gonadotrophin stimulation and a remarkably high T : dihydrotestosterone ratio. Sequencing of the five exons of the 5alpha-reductase type 2 gene (SRD5A2) was normal. Conversely, a de novo point mutation was found in exon 6 of the AR gene, resulting in an F804L substitution, which has never been described previously. To our knowledge, the association of complete AIS, congenital glaucoma and pyloric stenosis has also never been reported previously.