Infantile hypertrophic pyloric stenosis

Bilious vomiting does not rule out infantile hypertrophic pyloric stenosis

OBJECTIVE

To describe the incidence of bilious vomiting in infants with infantile hypertrophic pyloric stenosis that presented to a pediatric emergency department.

METHODS

A retrospective medical record review included all infants who presented to our level 1 pediatric emergency department from January 1, 2005, through December 31, 2009, who were diagnosed intraoperatively with infantile hypertrophic pyloric stenosis. Emesis was determined to be bilious if the vomit was described as "green," "containing bile," or "bilious."

RESULTS

The authors identified 354 infants with infantile hypertrophic pyloric stenosis. The median age was 4 weeks 6 days (range = 11 days to 13 weeks). Bilious emesis was encountered in 1.4% (5/354; 95% confidence interval = 0.5% to 3.2%). The pyloric thickness measurements on ultrasound were significantly smaller in those with bilious emesis compared with those without bilious emesis (z score = 2.64; P = .014).

CONCLUSION

Bilious emesis was the presenting symptom in a small proportion of infants with infantile hypertrophic pyloric stenosis.

Phasic and tonic smooth muscle function of the partially obstructed guinea pig intestine

This study was to generate phasic and tonic stress-strain curves for evaluation of smooth muscle function in the obstructed guinea pig jejunum. Partial and sham obstruction of the jejunum in guinea pigs was created surgically, with guinea pigs not being operated on served as normal controls. The animals survived 2, 4, 7, and 14 days, respectively. The jejunal segment was distended to 10 cm H₂O. The pressure and outer diameter changes were recorded. Passive conditions were obtained by using papaverine. Total phasic, tonic, and passive circumferential stress and strain were computed from the diameter and pressure data with reference to the zero-stress-state geometry. The active phasic and tonic stresses were defined as the total phasic and tonic stress minus the passive stress. The thickness of intestinal muscle layers increased in a time-dependent manner after obstruction. The amplitude of passive, total phasic, total tonic, active phasic, and active tonic circumferential stresses increased as function of strain 7 days after obstruction. However, when normalized to muscle layer thickness, the amplitude of active stresses did not differ among the groups. In conclusion, the long-term-obstructed intestine exhibits increased total smooth muscle contraction force. However, the contraction force per smooth muscle unit did not increase.

Pause and pulse: ten steps that help manage radiation dose during pediatric fluoroscopy

OBJECTIVE

The Image Gently Campaign of The Alliance for Radiation Safety in Pediatric Imaging seeks to increase awareness of opportunities to lower radiation dose in the imaging of children. Pause and Pulse is the most recent phase of the campaign, addressing methods of dose optimization in pediatric fluoroscopy.

CONCLUSION

This article discusses 10 steps that can be taken for fluoroscopic dose optimization in pediatric diagnostic fluoroscopy.

Factors contributing to prolonged hospitalization of patients with infantile hypertrophic pyloric stenosis

BACKGROUND

To study the influence of clinical audit on diagnosis, complications, and factors contributing to hospitalization of patients with infantile hypertrophic pyloric stenosis.

STUDY DESIGN

Retrospective cohort study.

METHOD

There were 214 patients from 1991 to 2004 from three medical centers in Kaohsiung. Data were analyzed with respect to diagnostic methods, complications, and factors requiring patient hospitalization.

RESULTS

The ratio of male to female was 4.8:1 (177 males and 37 females). The diagnoses before admission were as follows: 22% had milk intolerance and 14.5% had esophageal reflux. There was a significant increase in the use of sonogram diagnostic test (p=0.005) and a decrease in the incidence of diagnosis by olive mass palpation but not by barium meal test. Surgery time of 48 hours after admission was significant with barium meal examination and related to longer hospital stay (p<0.001). Weight gain less than 800 g before admission (n=125) was related to longer hospital stay (p=0.026).

CONCLUSION

The diagnostic method was changed from olive mass palpation to sonogram. Weight gain less than 800 g before admission and surgery time of 48 hours after admission were related to longer hospital stay.

Stress and strain analysis of contractions during ramp distension in partially obstructed guinea pig jejunal segments

Previous studies have demonstrated morphological and biomechanical remodeling in the intestine proximal to an obstruction. The present study aimed to obtain stress and strain thresholds to initiate contraction and the maximal contraction stress and strain in partially obstructed guinea pig jejunal segments. Partial obstruction and sham operations were surgically created in mid-jejunum of male guinea pigs. The animals survived 2, 4, 7 and 14 days. Animals not being operated on served as normal controls. The segments were used for no-load state, zero-stress state and distension analyses. The segment was inflated to 10 cmH(2)O pressure in an organ bath containing 37°C Krebs solution and the outer diameter change was monitored. The stress and strain at the contraction threshold and at maximum contraction were computed from the diameter, pressure and the zero-stress state data. Young's modulus was determined at the contraction threshold. The muscle layer thickness in obstructed intestinal segments increased up to 300%. Compared with sham-obstructed and normal groups, the contraction stress threshold, the maximum contraction stress and the Young's modulus at the contraction threshold increased whereas the strain threshold and maximum contraction strain decreased after 7 days obstruction (P<0.05 and 0.01). In conclusion, in the partially obstructed intestinal segments, a larger distension force was needed to evoke contraction likely due to tissue remodeling. Higher contraction stresses were produced and the contraction deformation (strain) became smaller.

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.

[Diagnostic imaging evaluation of neonatal vomiting]

Vomiting during the neonatal period is frequent. The purpose is to detect neonates and infants with digestive pathology requiring urgent management such as duodenal atresia, small bowel volvulus, acute intussusception, and hypertrophic pyloris stenosis. All of these conditions may be diagnosed by ultrasound which should be performed when clinically suspected.

Infantile hypertrophic pyloric stenosis: are viruses involved?

Infantile hypertrophic pyloric stenosis (IHPS) is characterized by abnormal thickening of the internal circular muscle layer. IHPS is known to be due to a combination of genetic and environmental factors, but its precise causes and pathophysiology are poorly understood. The objective of the study is to determine the prevalence of the principal viruses targeting the respiratory and digestive tracts in children with IHPS. Nasopharyngeal fluids, stools, vomit, and surgical pyloric muscle fragments and swabs were tested by cell culture, viral antigen assay and PCR. IHPS was diagnosed in 23 boys and 8 girls with a mean (±SD) age of 42 ± 15 days (range 20–88 days). There was no seasonal pattern of diagnosis. Twenty‐two children (71%) lost weight (mean 246 ± 164 g, range 30–600 g) after the onset of vomiting, and five (16.1%) were dehydrated. Seven (22.6%) infants had been exposed to an infectious contact within 15 days before admission, and one on the day of admission (3.2%). Ear, nose and throat samples and pyloric muscle specimens were negative for all the viruses tested. An adenovirus type 3 was recovered from one stool sample, and RT‐PCR was positive for an enterovirus on one vomit sample. This study suggests that the principal viruses targeting the respiratory and digestive tracts are not responsible for IHPS. J. Med. Virol. 82:2087–2091, 2010. © 2010 Wiley‐Liss, Inc.

3d Mechanical properties of the partially obstructed guinea pig small intestine

BACKGROUND AND AIMS

Partial obstruction of the small intestine results in severe hypertrophy of smooth muscle cells, dilatation and functional denervation. Hypertrophy of the small intestine is associated with alteration of the wall structure and the mechanical properties. The aims of this study were to determine three dimensional material properties of the obstructed small intestine in guinea pigs and to obtain the 3D stress-strain distributions in the small intestinal wall.

METHODS

Partial obstruction of mid-jejunum was created surgically in five guinea pigs that were euthanized 2 weeks after the surgery. Ten-cm-long segments proximal to the obstruction site were used for the stretch-inflation mechanical test using a tri-axial test machine. The outer diameter, longitudinal force and the luminal pressure during the test were recorded simultaneously. An anisotropic exponential pseudo-strain energy density function was used as the constitutive equation to fit the experimental loading curve and for computation of the stress-strain distribution.

RESULTS

The wall thickness and the wall area increased significantly in the obstructed jejunum (P<0.001). The pressure-outer radius curves in the obstructed segments were translated to the left of the normal segments, indicating wall stiffening after the obstruction. The circumferential stress and the longitudinal stress through the wall were higher in the obstructed segments (P<0.02). This was independent of whether the zero-stress state or the no-load states were used as the reference state.

CONCLUSION

The mechanical behaviour of the obstructed small intestine can be described using a 3D constitutive model. The obstruction-induced biomechanical properties change was characterized by higher circumferential and longitudinal stresses in the wall and altered material constants in the 3D constitutive model.

Testosterone levels in umbilical-cord blood and risk of pyloric stenosis

OBJECTIVE

The risk of infantile hypertrophk pylonc stenosis is ∼5 times more common in male than female infants. It has been hypothesized that the higher risk among male infants is associated with high levels of testosterone causing hypertrophy of the pylorus muscle. To test this hypothesis, we examined the association between the testosterone levels in the umbilical-cord blood and the risk of infantile hypertrophic pyloric stenosis.

PATIENTS AND METHODS

We conducted a matched case-control study nested in the Danish National Birth Cohort using risk-set sampling. From a cohort of 101 042 pregnancies, we identified umbilical-cord blood samples from 46 case subjects (43 male and 3 female infants) who developed infantile hypertrophic pyloric stenosis in the first year of life and 150 gender- and gestational age-matched control subjects. The testosterone levels were measured by liquid chromatography-tandem mass spectrometry. Rate ratios were estimated by using conditional logistic regression.

RESULTS

In male infants, the mean testosterone level at birth was 0.78 nmol/L in case subjects and 0.91 nmol/L in control subjects. The rate of infantile hypertrophic pyloric stenosis was inversely, albeit insignificantly, associated with the testosterone levels in male infants; there was a 29% (95% confidence interval: -46% to 65%; P = 35) lower rate per nmol/L. The association was not modified according to age, gestational age, or birth order.

CONCLUSIONS

We found no support for the hypothesis that high testosterone levels in the umbilical-cord blood are strongly associated with a subsequently higher risk for infantile hypertrophic pyloric stenosis in male infants.

Early developmental outcome of infants with infantile hypertrophic pyloric stenosis

PURPOSE

The study aimed to compare the developmental outcome of infants with infantile hypertrophic pyloric stenosis (IHPS) who underwent pyloromyotomy with healthy control infants in New South Wales (NSW), Australia.

METHODS

Infants diagnosed with IHPS requiring surgical intervention were enrolled prospectively between August 1, 2006, and July 31, 2008. Healthy control infants were enrolled in the same period. The children underwent a developmental assessment at 1 year of age (corrected) using the Bayley Scales of Infant and Toddler Development (Version III).

RESULTS

Of 52 infants with IHPS who were enrolled, 43 had developmental assessments. Most (90.6%) were term infants (>36 weeks gestation) with a median birth weight of 3237.8 g. Two infants (8%) had an associated birth defect, and survival was 100%. Developmental assessments were also performed on 211 control infants. Infants with IHPS scored significantly lower on the cognitive, receptive language, fine motor, and gross motor subscales compared to the control infants.

CONCLUSIONS

This unique study found lower than expected developmental scores for infants after surgery for IHPS than for healthy control infants. These findings raise concerns over the potential impact of IHPS and its surgical treatment. Further studies, including continuing developmental review to determine whether these differences persist and their functional importance, should be performed.

Hypertrophic Pyloric Stenosis

Hypertrophic pyloric stenosis (HPS) is a gastric outlet obstruction related to the thickening of the pyloric muscle. It typically affects first-born males between the ages of 6 to 8 weeks. Sonography is the modality of choice for diagnosing HPS. This review discusses the etiology, signs and symptoms, sonographic findings, and treatment for hypertrophic pyloric stenosis.

Biomechanical remodelling of obstructed guinea pig jejunum

Data on morphological and biomechanical remodelling are needed to understand the mechanisms behind intestinal obstruction. The effect of partial obstruction on mechanical properties with reference to the zero-stress state and on the histomorphological properties of the guinea pig small intestine was determined in this study. Partial obstruction and sham operation were surgically created in mid-jejunum of guinea pigs. The animals survived 2, 4, 7, and 14 days. The age-matched guinea pigs that were not operated served as normal controls. The segment proximal to the obstruction site was used for histological analysis, no-load state and zero-stress state data, and distension test. The segment for distension was immersed in an organ bath and inflated to 10cm H(2)O. The outer diameter change during the inflation was monitored using a microscope with CCD camera. Circumferential stresses and strains were computed from the diameter, pressure and the zero-stress state data. The opening angle and absolute value of residual strain decreased (P<0.01 and P<0.001) whereas the wall thickness, wall cross-sectional area, and the wall stiffness increased after 7 days obstruction (P<0.05, P<0.01). Histologically, the muscle and submucosa layers, especially the circumferential muscle layer increased in thickness after obstruction. The opening angle and residual strain mainly depended on the thickness of the muscle layer whereas the wall stiffness mainly depended on the thickness of the submucosa layer. In conclusion, the histomorphological and biomechanical properties of small intestine (referenced for the first time to the zero-stress state) remodel proximal to the obstruction site in a time-dependent manner.

Early pyloric stenosis: a case control study

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Sonographic evaluation of gastrointestinal obstruction in infants: a pictorial essay

Traditionally, gastrointestinal contrast studies have been the mainstay of evaluating infantile gastrointestinal problems. Because of technological advancements, good ultrasonography (USG) machines can provide high-resolution images with graphic anatomical clarity, especially in infants and children and thus change the traditional diagnostic trends. In this article, we illustrate the USG appearances of various causes of gastrointestinal obstruction in infants and discuss the role of USG in their evaluation.

Sonogram before and after pyloromyotomy: the pyloric ratio in infantile hypertrophic pyloric stenosis

BACKGROUND

Sonography is used to diagnose infantile hypertrophic pyloric stenosis, but Little information is available about the appearance of postoperative sonographs. The purpose of this study was to evaluate the morphology of the pylorus in association with an obstruction before and after pyloromyotomy.

METHODS

Pyloric length, diameter, muscle thickness and intermuscular space were measured sonographically at diagnosis and daily after pyloromyotomy until discharge in 12 infants with infantile hypertrophic pyloric stenosis. The ratios of pyloric wall thickness and intermuscular space to the entire pyloric diameter were measured.

RESULTS

The pylorus still appeared hypertrophied after pyloromyotomy on the sonograms. The traditional measurement of linear dimensions of the pylorus was not significantly changed from the preoperative values by the time of discharge, except for muscle thickness. The intermuscular space increased from 4.8+/-0.8 mm preoperatively to 7.3+/-2.1 mm by postoperative day 3 (p=0.10). Lowe's pyloric ratio at diagnosis was a mean of 0.32, decreasing to 0.29 on postoperative day 3 and 0.29 on the day of discharge (p=0.82). The alternative pyloric ratio increased significantly by postoperative day 2 (0.24+/-0.09 on day 2 vs. 0.11+/-0.07 preoperatively, p=0.02).

CONCLUSION

The pyloric ratio appears to be a reliable parameter in evaluating the regression of pyloric stenosis after pyloromyotomy, and also aids in the diagnosis of pyloric stenosis.

Return of the surgeon in the diagnosis of pyloric stenosis

BACKGROUND

The diagnosis of pyloric stenosis (PS) by physical examination is a lost art that has been replaced by radiology-performed ultrasound (US). The purpose of this study is to demonstrate that the diagnosis of PS can be made solely upon the surgeons US evaluation.

METHODS

Surgical ultrasonographers included 2 senior general surgery residents and 2 pediatric surgery residents without prior formal US experience. These surgeons underwent proctored training in the use of US for PS. Measurements including channel length and muscle thickness were recorded at bedside. A positive examination included muscle thickness more than 4 mm and channel length more than 16 mm. Patients with positive results underwent pyloromyotomy. Negative results were confirmed with a repeat US through the radiology department, and infants without PS were subsequently referred for appropriate medical management.

RESULTS

Thirty-two consecutive patients with suspected PS were evaluated using surgeon-performed ultrasonography. All examinations were diagnostically accurate. There were no false-positive or false-negative result. Seven patients (22%) were correctly determined to be negative for PS. The remaining 25 infants underwent successful pyloromyotomy with resolution of symptoms.

CONCLUSION

Surgeons who have undergone focused training to perform US for PS can diagnose the condition without confirmatory testing by a radiologist.

Surgeon-performed ultrasound for diagnosis of pyloric stenosis is accurate, reproducible, and clinically valuable

PURPOSE

We will demonstrate that a surgical resident with proven accuracy in the diagnosis of hypertrophic pyloric stenosis (HPS) can teach other surgeons to diagnose HPS with reproducible accuracy.

METHODS

A surgical resident with proven sonographic accuracy in diagnosing HPS instructed 5 other surgical residents in the technique. Consecutive patients referred to pediatric surgery with a presumed clinical diagnosis of HPS were examined, and measurements of residents were compared with formal radiology studies. Each surgeon was proctored for 5 examinations before independent evaluation and was blinded to results from both radiologists and other residents. Results were evaluated using Student's t test; P less than .05 was considered significant.

RESULTS

Seventy-one patients were evaluated by 5 surgical residents. Residents were diagnostically accurate in all cases. There was no statistically significant difference between pyloric muscle thickness or channel length measurements obtained by radiology and any of the residents.

CONCLUSION

Surgeon-performed ultrasound examination for the diagnosis of HPS is accurate and reproducible through surgeon-to-surgeon instruction on appropriate technique. This skill is a valuable asset in the initial surgical evaluation of any patient with suspected HPS, expediting appropriate management.

Transumbilical pyloromyotomy with umbilicoplasty provides ease of access and excellent cosmetic results

BACKGROUND/PURPOSE

Cosmesis is considered one of the key reasons to perform pyloromyotomies through the umbilicus. We describe the results of pyloromyotomy using a supraumbilical incision with umbilicoplasty that allows ease of mobilization of the pylorus and excellent cosmetic results.

METHODS

The charts of all patients undergoing transumbilical pyloromyotomy with umbilicoplasty from 2002 to 2006 were retrospectively reviewed. Demographic data as well as operative time, details of surgical technique, and outcome were collected and analyzed.

RESULTS

Thirty-eight patients underwent a transumbilical pyloromyotomy with umbilicoplasty. The average operative time was 39.2 minutes (range, 11-66 minutes). The time to tolerating feeds was 1.14 days (range, 1-3 days), and the average length of stay was 1.84 days (range, 1-8 days). There were 2 complications: periumbilical cellulitis (n = 1) and incisional hernia (n = 1). There were no perforations and no incomplete pyloromyotomies. The cosmetic results on postoperative follow-up were subjectively excellent.

CONCLUSIONS

Transumbilical pyloromyotomy with umbilicoplasty combines ease of exposure with ease of mobilization of the pylorus. There is minimal morbidity and an excellent cosmetic result. Time to average feeding, length of stay, and complications are similar to published reports of both open and laparoscopic pyloromyotomy.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Smaller scars--what is the big deal: a survey of the perceived value of laparoscopic pyloromyotomy

PURPOSE

Laparoscopic and open pyloromyotomies are equally safe and effective, with the principal benefit of laparoscopy being better cosmesis. The goal of this study was to measure the perceived value of laparoscopic pyloromyotomy.

METHODS

Four hundred sixteen subjects (177 college freshmen, 126 first-year medical students, and 101 parents) were asked to complete a questionnaire after photographs of mature pyloromyotomy (open and laparoscopic) scars were shown to them. To measure the perceived value, subjects' willingness to pay hypothetical additional out-of-pocket expenses for their preferred operation was assessed. Data were analyzed using Cochran-Mantel-Haenszel test, t test and multivariable regression.

RESULTS

Four hundred four surveys were complete. Overall, 74% preferred the appearance after laparoscopy. Eighty-eight percent would pay an additional out-of-pocket amount for their daughter and 85% for their son to have the cosmetic outcome after laparoscopy. Respondents were willing to pay more for their daughters (P < .0001) and sons (P < .0001) than themselves. As expected, income level (P < .0001) influenced the willingness to pay, whereas ethnicity, education, number of children, and sex did not.

CONCLUSIONS

The cosmetic benefit of laparoscopic pyloromyotomy was valued by a wide demographic with 85% being willing to pay additional expenses for their children to have smaller scars.

Spontaneous and bolus-induced motility in the chronically obstructed guinea-pig small intestine in vitro

Partial obstruction of the small intestine results in dysmotility and morphometric changes proximal to the site of obstruction. However, our understanding of the relation between the morphometric remodeling and change in the motility pattern during chronic obstruction is sparse. The aim of this study was to investigate the effect of partial chronic intestinal obstruction on motility, morphology, and collagen content proximal and distal to the site of obstruction. Twenty guinea-pigs with partial intestinal obstruction and eight sham-operated controls lived for four weeks. Spontaneous and bolus-induced motility was recorded in isolated intestinal segments proximal and distal to the site of obstruction using a perfused low-compliance pressure-measuring system in vitro. After the motility experiments, the specimens were fixed at 2 kPa luminal distension pressure and sampled for histomorphometric determination of luminal radius, layer thickness, and wall thickness. Total wall collagen was also determined. The area under the curve (AUC) of spontaneous contractions and the amplitude, frequency, and AUC for the bolus-induced motility were higher in the proximal segments of the banded animals compared to distal segments and to the intestinal segments in the control animals (P < 0.05). The radius-to-thickness ratio was lowest in the proximal segments of the obstructed animals (P < 0.01). The collagen content was three times higher proximal to the site of obstruction when compared to distal locations and to the controls (P < 0.01). The AUC at 2 ml bolus injections plotted against the radius-to-thickness ratio showed a strong association (r = 0.97 for control, and r = 0.99 for obstruction, P < 0.01). No correlation was found between the collagen content and AUC. In conclusion, partial intestinal obstruction in guinea pigs caused pronounced changes in morphology and motility. An association was found between the radius-to-thickness ratio and bolus-induced motility.

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

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

Ultrasound as a diagnostic tool used by surgeons in pyloric stenosis

PURPOSE

The purpose of the study was to validate surgeon-performed abdominal ultrasound in the diagnosis of pyloric stenosis, thus expediting diagnosis and management and increasing overall cost-effectiveness.

METHODS

A surgical resident, after completing ultrasound courses offered by the American College of Surgeons, Chicago, IL, examined 30 consecutive patients with a suspected diagnosis of hypertrophic pyloric stenosis (HPS). Blinded regarding both clinical and radiographic findings, the resident scanned the pylorus in longitudinal and transverse axes. Positive ultrasonographic evidence of HPS was defined as muscle thickness of at least 4 mm and/or channel length of at least 16 mm. Surgeon and radiology measurements were compared using descriptive analyses and Student t test.

RESULTS

There were 25 boys and 5 girls examined. Twenty-eight of 30 patients were found to have HPS. When ultrasound performed by the surgeon was compared with that of radiology, no false-negative or false-positive results were noted. The surgeon was diagnostically accurate in all cases, and there was no statistically significant difference between surgeon and radiology measurements with regard to pyloric muscle thickness (P = .825, mean deviation = 0.4 mm) or channel length (P = .74, mean deviation = 2.2 mm).

CONCLUSION

A surgeon with appropriate training in abdominal ultrasound can diagnose HPS with the same degree of accuracy as radiologists.

Descriptive epidemiology of selected birth defects, areas of Lombardy, Italy, 1999

BACKGROUND

Birth defects are a leading cause of neonatal and infant mortality in Italy, however little is known of the etiology of most defects. Improvements in diagnosis have revealed increasing numbers of clinically insignificant defects, while improvements in treatment have increased the survival of those with more serious and complex defects. For etiological studies, prevention, and management, it is important to have population-based monitoring which provides reliable data on the prevalence at birth of such defects.

METHODS

We recently initiated population-based birth defect monitoring in the Provinces of Mantova, Sondrio and Varese of the Region of Lombardy, northern Italy, and report data for the first year of operation (1999). The registry uses all-electronic source files (hospital discharge files, death certificates, regional health files, and pathology reports) and a proven case-generation methodology, which is described. The data were checked manually by consulting clinical records in hospitals. Completeness was checked against birth certificates by capture-recapture. Data on cases were coded according to the four-digit malformation codes of the International Classification of Diseases, Ninth Revision (ICD-9). We present data only on selected defects.

RESULTS

We found 246 selected birth defects in 12,008 live births in 1999, 148 among boys and 98 among girls. Congenital heart defects (particularly septal defects) were the most common (90.8/10,000), followed by defects of the genitourinary tract (34.1/10, 000) (particularly hypospadias in boys), digestive system (23.3/10,000) and central nervous system (14.9/10,000), orofacial clefts (10.8/10,000) and Down syndrome (8.3/10,000). Completeness was satisfactory: analysis of birth certificates resulted in the addition of two birth defect cases to the registry.

CONCLUSION

This is the first population-based analysis on selected major birth defects in the Region. The high birth prevalences for septal heart defect and hypospadias are probably due to the inclusion of minor defects and lack of coding standardization; the latter problem also seems important for other defects. However the data produced are useful for estimating the demands made on the health system by babies with birth defects.

Current management of hypertrophic pyloric stenosis

Hypertrophic pyloric stenosis (HPS) is a common condition affecting infants that presents with progressive projectile nonbilious vomiting. The pyloric portion of the stomach becomes abnormally thickened and manifests as gastric outlet obstruction. The cause is unknown. Pyloromyotomy remains the standard of treatment and outcome is excellent. This article reviews the diagnostic work up and imaging, preoperative resuscitation, the various surgical approaches used, and the effect of subspecialty training on outcomes after pyloromyotomy. Postoperative care and the variety of postoperative feeding regimens applied after pyloromyotomy are reviewed, as well as intra- and postoperative complications. Finally, medical management, in lieu of surgery, is discussed.

Biomechanical remodeling of the chronically obstructed Guinea pig small intestine

Small intestinal obstruction is a frequently encountered clinical problem. To understand the mechanisms behind obstruction and the clinical consequences, data are needed on the relation between the morphologic and biomechanical remodeling that takes place in the intestinal wall during chronic obstruction. We sought to determine the effect of partial obstruction on mechanical and morphologic properties of the guinea pig small intestine. Partial obstruction was created surgically in 2 groups of animals living for 2 and 4 weeks. Controls were sham operated and lived for 4 weeks. A combined impedance planimetry-high-frequency ultrasound system was designed to measure the luminal cross-sectional area and wall thickness. These measures were used to compute the circumferential stress and strain of the excised intestinal segments. The incremental elastic modulus was obtained by using nonlinear fitting of the stress-strain curve. Histologic analysis and the measurements of total wall collagen were also performed. The luminal cross-sectional area, wall thickness, and elastic modulus in circumferential direction increased in a time-dependent manner proximal to the obstruction site (P < 0.01), whereas no differences in these parameters were found distal to the obstruction site (P > 0.25). The circumferential stress-strain curves of the proximal segments in 2- and 4-week groups shifted to the left, indicating the intestinal wall became stiffer. Histologic examination revealed a massive increase in the thickness of the muscle layer especially the circular smooth muscle layer (P < 0.05). The collagen content proximal to the obstruction site was significantly larger in the partially obstructed animals compared to controls (P < 0.05). No difference was found distal to the obstruction site. Strong correlation was found between the collagen content and the elastic modulus at stress levels of 70 kPa stress (P < 0.01) and 10 kPa (P < 0.05) proximal to the obstruction site suggesting that the alteration of collagen has great impact on the mechanical remodeling. The morphologic and biomechanical remodeling likely influence the function of the intestine affected by partial obstructed intestine.

Low plasma nitrite in infantile hypertrophic pyloric stenosis patients

There is now substantial evidence that reduced expression of neuronal nitric oxide synthase (nNOS) is implicated in the pathogenesis of infantile hypertrophic pyloric stenosis (IHPS). This study aimed to investigate the role of plasma nitric oxide (NO) in patients with IHPS. Blood and pylorous biopsies of 13 IHPS patients were examined. The control group consisted of 19 age-matched healthy infants and 22 age-matched acute gastroenteritis patients. Plasma nitrite (NO(2-)) and nitrate (NO(3-)) levels were detected with an NO analyzer. Pylorus biopsies of 13 IHPS patients were examined for nitric oxide synthase isoform expression. Plasma nitrite levels in the 13 IHPS patients were significantly lower than in the age-matched healthy controls (0.97 +/- 0.19 vs. 3.53 +/- 0.79 microM; P < 0.001) and the acute gastroenteritis controls (0.97 +/- 0.19 vs.1.39 +/- 0.45 microM; P = 0.006). Decreased expression of nNOS in the nerve fibers of the pylorus circular muscle was found in the 13 IHPS patients. The decreased plasma nitrite levels rose to the normal range (3.27 +/- 0.77 M) after pyloromyotomy. There was no significant correlation between plasma nitrite levels and muscle wall thickness in IHPS patients. We conclude that NO is implicated in the occurrence of IHPS and the plasma nitrite level is valuable for the diagnosis of IHPS.

Changing trends in the management of infantile hypertrophic pyloric stenosis--an audit over 11 years

BACKGROUND

This article is a follow-up to an audit performed by the Department of Surgery and published in the Irish Journal of Medical Science in 1996. This audit reviewed all cases of Infantile Hypertrophic Pyloric Stenosis (IHPS) operated on over 22 years up to 1991.

AIMS

We aim to demonstrate that radiologic investigations, namely barium meal and ultrasound, have been increasingly employed in the diagnosis of IHPS. In addition, ultrasound is now the investigation of choice.

METHODS

We have reviewed all cases of IHPS, at the same institution, over the subsequent 11 years, with reference to any radiological investigations performed. In the previous study, the diagnosis of IHPS was made clinically in 92.6% with the remainder diagnosed radiologically.

RESULTS

Over 11 years, 157 patients were diagnosed with IHPS. Male to female ratio was 4.06:1. Median age was four weeks (range 1-18 weeks).Twenty-four per cent had a barium meal, 36% had an ultrasound and 13% had both performed.

CONCLUSION

We conclude a change in practice in the management of IHPS with radiology, particularly ultrasound, playing an increasing role.

The pylorus

The pylorus controls the flow between a reservoir dedicated to mechanical and chemical digestion (the stomach) and a conduit dedicated to the absorption of nutrients (the intestines). The pylorus adjusts gastric outflow resistance to physiological needs. It allows the outflow of isotonic fluids yet selectively retains particles too large for delivery to the intestines and in concert with the antrum further processes them (gastric sieving). Unlike most gut sphincters, the pylorus, at least of man, maintains a patent lumen most of the time. It only intermittently becomes a tightly closed barrier that arrests all flow out of and into the stomach. The geometry of the pylorus changes dramatically from the relaxed open state to closure. Pyloric closure involves contraction of its proximal and distal muscle loops, and occlusion of its lumen by mucosal folds. Current studies that combine pressure recordings with imaging by magnetic resonance imaging or ultrasound and fluid-mechanical analysis shed new light on the role of the pylorus in gastric emptying and digestion. Much has been learned in recent years on the innervation of the normal pylorus particularly from studies on infantile hypertrophic stenosis, and attempts are being made to treat gastroparesis by interventions on the pylorus.

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

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

Ultrasound evaluation of acute abdominal emergencies in infants and children

Ultrasound is extremely beneficial in the evaluation of acute pediatric abdominal disease, such as HPS, intussusception, and acute appendicitis. As techniques and equipment improve, its role in the evaluation of infants and children continues to increase.