The enigma of pyloric stenosis. Some thoughts on the aetiology

Factors associated with pyloric hypertrophy severity and post-operative feeding and nutritional recovery in infantile hypertrophic pyloric stenosis

BACKGROUND

To examine factors that affect the severity of pyloric hypertrophy, post-operative feeding and nutritional recovery in infantile hypertrophic pyloric stenosis (IHPS).

METHODS

Medical records of infants diagnosed with IHPS at a single tertiary center between 2009 and 2018 were retrospectively reviewed. Clinical characteristics, biochemistry data and outcome were assessed for their association with the severity of pyloric hypertrophy and post-operative recovery. Nutritional recovery was assessed using weight-for-age status improvement after surgery.

RESULTS

Eighty-five patients were recruited in this study. The mean pre-operative weight-for-age percentile was 18.2. Elevated bicarbonate was positively correlated with symptom duration (p = 0.007). Pyloric muscle thickness was significantly correlated with age, weight, and symptom duration (p = 0.004, 0.003, 0.008, respectively). The mean weight-for-age percentile increased to 41.6 by post-operative weeks 6-8. Pyloric muscle thickness was negatively correlated with nutritional recovery by post-operative weeks 6-8 (p = 0.003). In multivariable analysis, pyloric length related to nutritional recovery at week 1-2 postoperatively (OR = 1.42, p = 0.030, 95% CI = 0.03-1.94), and pyloric muscle thickness related to nutritional recovery at week 6-8 postoperatively (OR = 4.08, p = 0.032, 95% CI = 1.13-14.7).

CONCLUSION

Our study indicated that favorable nutritional outcome and successful weight gain was observed 6-8 weeks after surgery in children with IHPS. Pyloric muscle thickness positively correlated with age, weight, symptom duration, and favorable nutritional recovery. Serum bicarbonate showed a positive correlation with symptom duration.

Safety and benefit of ad libitum feeding following laparoscopic pyloromyotomy: retrospective comparative trial

PURPOSE

In this study, we evaluated the impacts of ad libitum feedings on outcomes following laparoscopic pyloromyotomy in patients with infantile hypertrophic pyloric stenosis.

METHODS

Pediatric patients with infantile hypertrophic pyloric stenosis who underwent laparoscopic pyloromyotomy were included. Patients were stratified into ad libitum and structured feeding groups. Primary outcomes were times from surgery completion to goal feeding and discharge.

RESULTS

A total of 336 patients were included in the study with 63 patients (18.8%) in the ad libitum feeding group. The ad libitum feeding group experienced significantly shorter times from surgery completion to both goal feedings (10.7 h vs 18.7 h; p < 0.001) and hospital discharge (21.6 h vs 23.1 h; p = 0.008) compared to the structured protocol group. Postoperative emesis (47.% vs 30.8%; p = 0.011) was higher in the ab libitum cohort, but the rates of return to an emergency department and/or readmission (4.8% vs 2.2%; p = 0.26) were similar.

CONCLUSION

Ad libitum feeding after pyloromyotomy decreases time to reach goal feeding and hospital discharge. While it may contribute to a higher incidence of emesis, it does not appear to significantly increase hospital readmission. Ad libitum feeding appears to be a safe and beneficial alternative to structured feeding protocols following pyloromyotomy.

LEVEL OF EVIDENCE

III.

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.

Focal pyloric hypertrophy in adults: a diagnostic pitfall-a case report and review of the literature

Adult hypertrophic pyloric stenosis in the form of focal pyloric hypertrophy is an uncommon but a well-established lesion. In most cases, clinical findings suggest malignancy, and despite advances in imaging techniques, preoperative diagnosis is difficult. Herein, an example of focal pyloric hypertrophy is presented with a review of the literature to emphasize the clinicopathological characteristics of this lesion. In a 43-year-old man with abdominal discomfort, endoscopy showed a 1.5 cm nodular lesion near the pylorus that necessitated surgery to exclude malignancy. Pathological examination allowed the diagnosis of focal pyloric hypertrophy. The present case and the review revealed that focal pyloric hypertrophy is a male dominant lesion in middle-aged patients. The clinical diagnosis is problematic, and its initial diagnosis depends on a high clinical suspicion in patients with upper gastrointestinal system complaints irrespective of the duration of the symptoms. It is not known whether it is a separate entity from the diffuse form. Although both are similar in a clinical point of view, etiopathogenetic studies are required to clarify their differences completely. Moreover, the rare occurrence of focal pyloric hypertrophy and the lack of diagnostic clinical findings do not exclude its consideration in the differential diagnosis, especially in patients with gastric outlet obstruction.

Interstitial cells of Cajal, the Maestro in health and disease

Interstitial cells of Cajal (ICC) are important players in the symphony of gut motility. They have a very significant physiological role orchestrating the normal peristaltic activity of the digestive system. They are the pacemaker cells in gastrointestinal (GI) muscles. Absence, reduction in number or altered integrity of the ICC network may have a dramatic effect on GI system motility. More understanding of ICC physiology will foster advances in physiology of gut motility which will help in a future breakthrough in the pharmacological interventions to restore normal motor function of GI tract. This mini review describes what is known about the physiologic function and role of ICCs in GI system motility and in a variety of GI system motility disorders.

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.

Cord blood leptin and IGF-I in relation to birth weight differences and head circumference in monozygotic twins

OBJECTIVES

To investigate a potential role of leptin and insulin-like growth factor (IGF)-I on fetal growth and metabolic function we determined plasma leptin and IGF-I concentrations in twins in relation to discordant fetal growth.

STUDY DESIGN

In studying monochorionic twins with inter-twin birth weight difference, we investigated the relative contribution of genetic (fetus) versus environmental (maternal/placental) factors on growth. Thirty-six sets of twins (14 with discordant growth, birth weight difference >15%) who had been treated for severe twin-to-twin transfusion syndrome (TTTS) by laser coagulation were studied. Cord blood samples were collected at birth and analyzed for IGF-I and leptin. Inter-twin differences (delta) of birth weight and head circumference were correlated to delta hormone levels.

RESULTS

An inter-twin correlation for leptin (r = 0.69; p <0.0001) and delta IGF-I (r = 0.49; p <0.0001) was found. delta birth weight correlated significantly with delta IGF-I (r = 0.67; p <0.0001) but not with delta leptin (r = 0.23; p = 0.19). delta IGF-I concentrations did not correlate with delta leptin (r = 0.18). delta head circumference correlated significantly with delta leptin (r = 0.47; p <0.01) and with delta IGF-I (r = 0.46; p <0.01). Using a multiple regression model with head circumference as dependent variable, adjusted for gestational age, head circumference remained significantly associated with higher leptin concentrations in all patients (p = 0.03).

CONCLUSION

IGF-I is a good indicator for fetal growth and brain development. Leptin seems to be mainly genetically determined but may play a role in fetal brain development and is not only an index for fetal fat mass.

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.

Hypertrophic pyloric stenosis in infants: US evaluation of vascularity of the pyloric canal

PURPOSE

To determine if there is increased flow to the pylorus in infants with hypertrophic pyloric stenosis (HPS) and, if so, whether the flow is localized to the muscle layer, mucosal layer, or both.

MATERIALS AND METHODS

Seventy-five infants examined for clinical suspicion of HPS were prospectively recruited for the study. Color scale was standardized at 4.2-4.4 cm/sec. Color Doppler flow at ultrasonography (US) was graded as follows: Grade 1 meant no signal; grade 2, two to five flow signals; and grade 3, extensive or continuous flow. Flow to the muscle or mucosal layer was documented and confirmed with spectral analysis. Infants without HPS served as control patients. Descriptive analyses were conducted to assess the demographic data and US results. Significance was assessed with chi2 or t tests. P <.05 was considered to indicate a significant difference.

RESULTS

HPS was present in 41 infants with a mean age of 5 weeks +/- 2.0 (SD). Their mean flow grade was 2.80 +/- 0.4 in muscle and 2.88 +/- 0.4 in mucosa. HPS was not present in 34 infants with a mean age of 5.9 weeks +/- 4.5. Their mean flow grade was 1.26 +/- 0.5 in muscle and 1.15 +/- 0.5 in mucosa (P <.001). There was no significant difference in flow grades when the dimensions of the pyloric muscle and mucosa were compared. There was no significant difference in age between the HPS and control patient groups.

CONCLUSION

Increased flow accompanies and may conceivably represent an integral component of the changes that occur with infantile HPS.

Infantile hypertrophic pyloric stenosis

Infantile hypertrophic pyloric stenosis is a common condition affecting young infants; despite its frequency, it has been recognized only for a little over a century, and its etiology remains unknown. Nevertheless, understanding of the condition and of effective treatment have undergone a remarkable evolution in the 20th century, reducing the mortality rate from over 50% to nearly 0%. The lesion is characterized by gastric outlet obstruction and multiple anatomic abnormalities of the pyloric antrum. The antropyloric muscle is abnormally thickened and innervated, and the intervening lumen is obstructed by crowded and redundant mucosa. Recognition of the obstructive role of the mucosa led to discovery of effective surgical treatment. Accurate clinical diagnosis in patients in whom a thickened antropyloric muscle is not readily palpable can be difficult, resulting in delayed diagnosis and can lead to emaciation and electrolyte imbalance, making the patient a suboptimal surgical candidate. Current imaging techniques, particularly sonography, are noninvasive and accurate for identification of infantile hypertrophic pyloric stenosis. Successful imaging requires understanding of anatomic changes that occur in patients with this condition and plays an integral role in patient care. Accurate, rapid, noninvasive imaging techniques facilitate rapid referral of vomiting infants and prompt surgical treatment of more suitable surgical candidates.

The association of erythromycin and infantile hypertrophic pyloric stenosis: causal or coincidental?

The safety profile of erythromycin is notable for the frequent occurrence of intolerable gastrointestinal effects. One of the more serious of these is infantile hypertrophic pyloric stenosis (IHPS). A recent cluster of IHPS cases prompted an epidemiological investigation which identified oral erythromycin chemoprophylaxis of pertussis as the major risk factor. Evidence suggests an association between early postnatal erythromycin exposure and IHPS. There is no substantive evidence of a risk associated with prenatal exposure, with the single published case-control study to date producing negative findings. The epidemiological investigations of the association with early postnatal exposure have reported significantly elevated odds ratios but have a variety of methodological limitations that prevent definitive conclusions being made. Nevertheless, the concordance of findings across studies increases the strength of evidence favouring an association. The prominent gastrokinetic properties of erythromycin have been postulated as the mechanism behind this phenomenon. A comprehensive assessment of this potential adverse effect should consider its biological plausibility in light of known gastrointestinal physiology, its modulation by erythromycin, and the known pathophysiology of IHPS. Gastrointestinal motor activity in the fasted mammal consists of three phases, phase III being large amplitude contractions called migrating motor complexes (MMC) that can be initiated by motilin and erythromycin. The gastrokinetic effects of erythromycin are variable and complex and include effects on the timing, duration, amplitude and distribution of MMCs. It has been speculated that the motilinomimetic effects of erythromycin on antral smooth muscle function, such as the MMC, may mediate the effect via work hypertrophy. Although intuitively plausible and consistent with hypertrophic obstructive changes similar to IHPS observed in hyperplastic rat ileum after artificially induced mechanical obstruction, there is no direct evidence of this phenomenon. Further complicating the association is the limitations of our knowledge about the pathophysiology of IHPS, including numerous genetic abnormalities, increased parietal cell mass, and gastric hyperacidity. The implications of the reported findings with erythromycin on the benefit-risk profiles of newer macrolides and azalides must be considered. The available data on the comparative gastrokinetic properties of macrolides are significant for the potent gastrokinetic properties and its acid degradation products, the marked variation in gastrokinetic properties associated with macrolide ring size, and the requirement for specific glycosidic linkages at the C-3 and C-5 carbons of the macrolide ring. The variation in gastrokinetic properties associated with variations in molecular structure suggests that if the association between erythromycin and IHPS is causal it may not be a class effect.

In vivo visualization of pyloric mucosal hypertrophy in infants with hypertrophic pyloric stenosis: is there an etiologic role?

OBJECTIVE

Infantile hypertrophic pyloric stenosis (IHPS) is a common condition which presents in infants at 2-12 weeks of postnatal life, and whose cause remains obscure. Multiple associated abnormalities have been recognized within the external hypertrophied pyloric muscle layer, but the internal component of the pyloric mucosa has received scant attention in the literature to date. Our purpose in this study was to show that pyloric mucosal redundancy is a constant finding in infants with IHPS, to discuss its possible cause, and to explore the hypothesis of a relationship between pyloric mucosal redundancy and the development of IHPS.

MATERIALS AND METHODS

We identified 102 consecutive infants with surgically confirmed IHPS and determined the thickness of the pyloric mucosa compared with the thickness of the surrounding hypertrophied muscle. Fifty-one infants who did not have pyloric stenosis served as controls.

RESULTS

Mean mucosal thickness in patients with IHPS approximated mean muscle thickness, with a ratio of 0.89. In infants with IHPS, the pyloric mucosa constitutes approximately one third of the cross-sectional diameter of the pyloric mass and fills and obstructs the pyloric canal.

CONCLUSION

Mucosal redundancy is a constant associated finding in IHPS. Although the origin of the redundancy and a cause-and-effect relationship are difficult to establish, our findings support the hypothesis that hypergastrinemia may be implicated in the pathogenesis of IHPS, and suggest that mucosal thickening could be implicated as one of the initiating factors in its development.

Interstitial cells of Cajal in human gut and gastrointestinal disease

This paper reviews the distribution of interstitial cells of Cajal (ICC) in the human gastrointestinal (GI) tract, based on ultrastructural and immunohistochemical evidence. The distribution and morphology of ICC at each level of the normal GI tracts is addressed from the perspective of their functional significance. Alterations of ICC reported in achalasia of cardia, infantile hypertrophic pyloric stenosis, chronic intestinal pseudoobstruction, Hirschsprung's disease, inflammatory bowel diseases, slow transit constipation, and some other disorders of GI motility as well as in gastrointestinal stromal tumors are reviewed, with emphasis on the place of ICC in the pathophysiology of disease.

Interstitial cells of Cajal in human gut and gastrointestinal disease

This paper reviews the distribution of interstitial cells of Cajal (ICC) in the human gastrointestinal (GI) tract, based on ultrastructural and immunohistochemical evidence. The distribution and morphology of ICC at each level of the normal GI tracts is addressed from the perspective of their functional significance. Alterations of ICC reported in achalasia of cardia, infantile hypertrophic pyloric stenosis, chronic intestinal pseudoobstruction, Hirschsprung's disease, inflammatory bowel diseases, slow transit constipation, and some other disorders of GI motility as well as in gastrointestinal stromal tumors are reviewed, with emphasis on the place of ICC in the pathophysiology of disease.