Hypertrophic pyloric stenosis: determination of muscle dimensions by ultrasound

An Unusual Presentation of Pyloric Stenosis: A Case Report

A full-term newborn female presented with non-bilious emesis immediately after feeding and abdominal distension on day one of life with neither palpable abdominal mass nor electrolyte derangements. The baby was initially admitted to rule out gastrointestinal obstruction versus sepsis as a cause of vomiting and abdominal distension. Initial imaging studies involving an upper gastrointestinal (GI) series showed obstruction at the level of the duodenum, but it was only during surgical exploration that the diagnosis of infantile hypertrophic pyloric stenosis was made. This case report highlights the atypical presentation of pyloric stenosis and the need to investigate cases of vomiting immediately after feeding in a newborn with ultrasonography at the least to minimize complications.

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.

Feasibility of Point-of-Care Ultrasound for Diagnosing Hypertrophic Pyloric Stenosis in the Emergency Department

OBJECTIVES

This study aimed to investigate the feasibility of point-of-care ultrasound (POCUS) for diagnosing hypertrophic pyloric stenosis (HPS) in the emergency department (ED).

METHODS

A retrospective study was conducted in infants aged younger than 90 days who were brought to the ED due to vomiting between January 2015 and December 2019. Of these, infants who were clinically suspected of having HPS and underwent ultrasound were included and categorized into 3 groups: POCUS only, POCUS followed by radiologist-performed ultrasound (RADUS), and RADUS only. All confirmative diagnoses of HPS were made by RADUS. The diagnostic performance of POCUS was analyzed, and the ED patient flow was compared between the POCUS-performed (POCUS only or POCUS followed by RADUS) and RADUS-only groups.

RESULTS

Overall, 171 patients with a median age of 34 days were included. Of these, 79 patients (46.2%) underwent POCUS only, and none had HPS; 50 patients (29.2%) underwent POCUS followed by RADUS; and 42 patients (24.5%) underwent RADUS only. Overall, 41 patients (24.0%) were diagnosed with HPS, and POCUS showed a sensitivity of 96.6% and specificity of 94.0%. In the total cohort, length of stay in the ED (EDLOS) was shorter in the POCUS-performed group than in the RADUS-only group (2.6 vs 3.8 hours, P = 0.015). Among non-HPS patients, time to disposition (1.8 vs 2.7 hours, P = 0.005) and EDLOS (2.0 vs 3.0 hours, P = 0.004) were shorter in the POCUS-performed group than in the RADUS-only group. Performing POCUS followed by RADUS did not significantly delay the treatment among HPS patients.

CONCLUSIONS

Point-of-care ultrasound is accurate and useful for diagnosing HPS and improved the ED patient flow by reducing EDLOS and door-to-disposition time in non-HPS patients.

Are we performing ultrasound measurements of the wall thickness in hypertrophic pyloric stenosis studies the same way?

PURPOSE

To retrospectively review imaging planes, number of visible pyloric layers and location of measurements, in infants with suspected (HPS).

METHODS

103 pyloric ultrasound studies for suspected HPS were included. For each study, we recorded whether longitudinal or transverse views were performed, the layers visualized (a schematic was developed for two pediatric radiologists to categorize the interfaces of the anatomic layers a-e) and position of the internal measurement cursor. Categories for the anterior (superficial wall) layers were from external to internal: (a) internal aspect of the muscularis propria; (b) external aspect of the muscularis mucosa; (c) internal aspect of the muscularis mucosa; (d) internal aspect of the mucosa interfacing with a mucosal fold (e) deep aspect of the mucosal fold. Median differences between HPS groups were calculated and inter-reader agreement (kappa score) was performed between both readers.

RESULTS

In 100 studies (97 patients), longitudinal (99%) and transverse (69%) views of the pylorus were recorded. For longitudinal views, measurements included muscle thickness (95%), length (97%) and no pyloric diameter. For the transverse view, measurements included muscle thickness (16%) and the diameter (3%). Pyloric layer interfaces were visible: (a) in 64% (b) in 64% (c) in 66% (d) in 30% and (e) in 26%. The internal reference point of cursor placement for measuring the muscle wall thickness in the longitudinal view for one reader was as follows: (a) 46% (b) 27% (c) 30% (d) 1% and (e) 2% of studies. Surgically proven HPS group had a median thickness measurement 0.17 mm greater than the non-HPS studies (CI 95% 0.12-0.21, p < 0.05), and inter-reader agreement was considered as moderate (Kappa 0.5).

CONCLUSIONS

We found a variety of thickness measurements performed predominantly in the longitudinal view and a largely abandoned diameter measurement. The latter might offer a solution as it is not defined by any internal interfaces.

Pediatric emergency medicine point-of-care ultrasound: summary of the evidence

The utility of point-of-care ultrasound is well supported by the medical literature. Consequently, pediatric emergency medicine providers have embraced this technology in everyday practice. Recently, the American Academy of Pediatrics published a policy statement endorsing the use of point-of-care ultrasound by pediatric emergency medicine providers.  To date, there is no standard guideline for the practice of point-of-care ultrasound for this specialty. This document serves as an initial step in the detailed “how to” and description of individual point-of-care ultrasound examinations.  Pediatric emergency medicine providers should refer to this paper as reference for published research, objectives for learners, and standardized reporting guidelines.

Evaluation of hypertrophic pyloric stenosis by pediatric emergency physician sonography

OBJECTIVES

The objective was to evaluate the accuracy of pediatric emergency physician (EP) sonography for infants with suspected hypertrophic pyloric stenosis (HPS).

METHODS

This was a prospective observational pilot study in an urban academic pediatric emergency department (PED). Patients were selected if the treating physician ordered an ultrasound (US) in the department of radiology for the evaluation of suspected HPS.

RESULTS

Sixty-seven patients were enrolled from August 2009 through April 2012. When identifying the pylorus, pediatric EPs correctly identified all 10 positive cases, with a sensitivity of 100% (95% confidence interval [CI] = 62% to 100%) and specificity of 100% (95% CI = 92% to 100%). There was no statistical difference between the measurements obtained by pediatric EPs and radiology staff for pyloric muscle width or length (p = 0.5 and p = 0.79, respectively).

CONCLUSIONS

Trained pediatric EPs can accurately assess the pylorus with US in the evaluation of HPS with good specificity.

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.

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.

Intravenous Atropine Treatment in Hypertrophic Pyloric Stenosis: Evaluation by Clinical Course and Imaging

Hypertrophic pyloric stenosis (HPS) is the principal disease to consider in neonates presenting with frequent projectile vomiting and poor weight gain. Ramstedt pyloromyotomy is commonly used for the surgical treatment of HPS. The present study investigated the efficacy of nonsurgical medical treatment using intravenous administration of atropine and the examined the clinical course and results of ultrasonography and a contrast upper gastrointestinal series. A 34-day-old girl was admitted with chief complaints of projectile vomiting and poor weight gain. HPS was diagnosed on the basis of the clinical course and results of imaging studies. After intravenous administration of atropine, projectile vomiting resolved and weight increased without complications. On imaging studies, barium introduced into the stomach by tube rapidly entered the duodenum after atropine administration. Ultrasonography initially showed no reductions in hypertrophic muscle in the pyloric region, but gradual reductions were identified in subsequent months.

Ultrasound diagnosis of infantile hypertrophic pyloric stenosis: determinants of pyloric length and the effect of prematurity

AIM

To evaluate the determinants of sonographic measurements of pyloric length and muscle thickness in infants with hypertrophic pyloric stenosis (HPS) and to determine whether infants born prematurely have proportionately smaller measurements.

MATERIALS AND METHODS

A retrospective review was carried out of 190 infants operated on for HPS at Bristol Children's Hospital over a 5-year period. Sonographic measurements of pyloric length and muscle thickness were related to age, history of prematurity, weight, sex and family history of HPS.

RESULTS

Pyloric length in infants with HPS was significantly greater in those born at term compared to those born prematurely (18.6 mm [SD 2.2] vs 17.3 mm [SD 3.1], P = 0.043); this was explainable by body weight, with length increasing by 1.13 mm (SE 0.35) per kilogram (P = 0.002). There was no significant relationship with measured muscle thickness.

CONCLUSION

Sonographic measurement of pyloric length is strongly correlated with the weight of the infant, irrespective of other factors. The relationship of length and weight may be useful in confirming the presence of HPS in small and premature infants.

Surgeon-performed ultrasound imaging in acute surgical disorders

As the role of the general surgeon continues to evolve, the surgeon's use of ultrasound imaging will surely influence practice patterns, particularly for the evaluation of patients in the acute setting. With the use of real-time imaging, the surgeon receives "instantaneous" information to augment the physical examination, to narrow the differential diagnosis, or to initiate an intervention. With select ultrasound examinations, the surgeon can rapidly evaluate adult and pediatric patients with an acute abdomen, especially those patients who are hypotensive. In the hands of the surgeon, this noninvasive, bedside tool can assess more accurately the presence, depth, and extent of an abscess, confirm complete aspiration, or diagnose wound dehiscence before it is apparent on physical examination. Ultrasound imaging is so accurate for the diagnosis of pyloric stenosis that it has essentially replaced the upper gastrointestinal series in most institutions. The surgeon's use of ultrasound imaging to detect a pleural effusion has virtually supplanted the lateral decubitus radiograph. Furthermore, an ultrasound-guided thoracentesis not only facilitates the procedure but improves its safety. As surgeons become more facile with ultrasound imaging, it is anticipated that other uses will develop to further enhance its value for the assessment of patients in the acute setting.

The surgeon's use of ultrasound in the acute setting

As the role of the general surgeon continues to evolve, the surgeon's use of ultrasound will surely influence practice patterns, particularly for the evaluation of patients in the acute setting. With the use of real-time imaging, the surgeon receives "instantaneous" information to augment the physical examination, narrow the differential diagnosis, or initiate an intervention. With select ultrasound examinations, the surgeon can rapidly evaluate adult and pediatric patients who present with an acute abdomen, especially those in shock. In the hands of the surgeon, this noninvasive bedside tool can more accurately assess the presence, depth, and extent of an abscess, confirm complete aspiration, or diagnose wound dehiscence before it is apparent on physical examination. Ultrasound is so accurate for the diagnosis of pyloric stenosis that it has essentially replaced the upper gastrointestinal series in most institutions. The surgeon's use of ultrasound to detect a pleural effusion has virtually replaced the lateral decubitus film. Furthermore, an ultrasound-guided thoracentesis not only facilitates the procedure but improves its safety. Many ICUs now have protocols in place to perform routine duplex surveillance of those patients who are considered at high risk for the development of thromboembolic complications. As surgeons become more facile with ultrasound, it is anticipated that other uses will develop to further enhance its value for the assessment of patients in the acute setting.

Prostaglandin-induced foveolar hyperplasia simulating pyloric stenosis in an infant with cyanotic heart disease

Prostaglandin infusion is used to maintain patency of the ductus arteriosus in infants with cyanotic congenital heart disease. Recently, gastric outlet obstruction as a result of prostaglandin infusion has been described. In our case, an upper gastrointestinal contrast study seemed to depict the typical appearance of pyloric stenosis in an infant who had received an infusion of prostaglandin for a prolonged period. Serial ultrasonograms, however, disclosed progressive elongation of the antropyloric channel without wall thickening. This report is the second to illustrate prostaglandin-induced gastric outlet obstruction in a vomiting infant with a gastrointestinal series diagnosis of pyloric stenosis.

Pyloric stenosis in a premature infant

Workup of a case of hypertrophic pyloric stenosis in a premature infant showed absence of ultrasonic criteria for diagnosis. Transpyloric intubation for enteral feeding may delay the diagnosis of this disorder and has been thought to play a role in its development.