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

https://doi.org/10.1016/j.jpedsurg.2008.02.022Get rights and content

Abstract

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.

Section snippets

Diagnosis of HPS

After approval from the institutional review board at the University of Pittsburgh Medical Center (Protocol #0608200), Pittsburgh, Pa, a chart review of patients admitted to the Children's Hospital of Pittsburgh, Pittsburgh, Pa, between January 1, 2001, and December 31, 2006, requiring surgical intervention for HPS, was performed. Patients were identified by discharge diagnosis of congenital pyloric stenosis (ICD-9 code 750.5) and the procedure code for pyloromyotomy (433). Standard controls

Demographics

Between 2001 and 2006, there were 314 patients between the ages of 0 and 42 days that presented to the Children's Hospital of Pittsburgh for surgical correction of HPS (Table 1). Of these, 96% were white and 83% were male, and 12% had a family history of HPS in a first-degree relative. There were 8 pairs of twins, in which the diagnosis of HPS was made in both twins on 2 occasions. Thirty patients (10%) had diagnostic imaging performed at outside hospitals before their admission to our

Discussion

Given the relative frequency with which newborns younger than 22 days present with HPS (and the paucity of diagnostic information relevant to this “young” population), we sought in the current study to investigate the pyloric thickness and channel length of newborns younger than 22 days, requiring surgical correction for HPS. We now describe that the pyloric MT was significantly smaller in these “younger” patients than in older counterparts. We also detected a linear relationship between

References (12)

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    More than 2 decades later, these same criteria are still applied across the entire spectrum of infants being evaluated for PS regardless of age or weight. In fact, because more recent studies have correlated US measurements to age and weight, the applicability of decades-old criteria needs to be readdressed [8,9]. However, these reports demonstrating correlations between age and weight with US measurements have not looked at those infants who had negative ultrasounds and, therefore, have not been able to adequately assess the sensitivity and specificity of US in the diagnosis of PS to determine if new criteria based on age and weight are necessary.

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    Although radiologists most often make the diagnosis, Copeland and colleagues [16] report that surgeons who have undergone focused training can diagnose the condition without confirmatory testing by a radiologist. Despite the high specificity and sensitivity of diagnostic methods, the current guidelines may not be sufficient for accurate diagnosis of IHPS in infants younger than 3 weeks because of the thin pyloric muscle thickness [19] and equivocal clinical and biochemical variables [14]. Young infants should be observed and reevaluated in 1 to 2 days when the lesion may be more clinically or radiologically evident [20].

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Presented at the 59th Annual Meeting of the Section on Surgery, American Academy of Pediatrics, San Francisco, CA, October 25-27, 2007.

CLL is supported in part by the Loan Repayment Program for Pediatric Research of the National Institutes of Health.

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