Pylorospasm: a less common functional disorder mimicking hypertrophic pyloric stenosis, leading to persistent vomiting in a preterm male infant

Abstract

Introduction and importance:

Historically, pylorospasm is defined as a condition in which the pyloric canal of the infant has a functional obstruction as opposed to an organic one, compared to hypertrophic pyloric stenosis (HPS), a well-known cause of post-feeding and repetitive vomiting in infancy.

Case presentation:

We have reported a case of a premature male infant born via surrogacy and fed from a milk bank, whose acute after-meal intermittent vomiting led to a pylorospasm diagnosis. He was successfully treated non-surgically by intravenous (IV) atropine and gained weight.

Clinical discussion:

It has been 61 years since the first use of oral atropine for treating HPS, especially in children with anesthesia or surgery who have restrictions. Subsequently, in limited trials, IV atropine was introduced for its more effective and less complicated nature.

Conclusion:

In cases of suspicion of HPS without sonographic evidence, pylorospasm should be kept in mind, and in these conditions, atropine can be a suitable and less complicated therapeutic alternative.

Introduction

It was first Hughson in 1925 who introduced the expression pylorospasm^[1^]. There is still limited information on this rare condition: a condition in which the pyloric canal of the infant has functional obstruction due to organic causes, distinct from hypertrophic pyloric stenosis (HPS), or, more precisely, infantile hypertrophic pyloric stenosis (IHPS). Pylorospasm is a cause of delayed gastric emptying in young infants. Similar to patients diagnosed with HPS, most pylorospasm patients exhibit projectile vomiting. In contrast to HPS, persistent pyloric stenotic lesions are absent. Furthermore, the use of serial gastrointestinal fluoroscopy or ultrasonography can assist in diagnosing patients presenting with clinical signs of gastroparesis. While most cases can be managed conservatively, some patients require pharmacologic intervention. Using antispasmodic agents as a potential treatment for pylorospasm has been suggested, although their application in neonates and infants has been rarely documented. Historically, the condition “pylorospasm” was frequently diagnosed by experienced radiologists in cases in which the barium-filled stomach demonstrated delayed or incomplete emptying, without an organic lesion, within a specified time frame. Our report highlights a case of infantile pylorospasm in a 6-day-old premature male neonate, which was effectively managed through the use of atropine. The content of this work meets the criteria outlined in SCARE 2025^[2^].

HIGHLIGHTS

• Vomiting in a neonate is always severe and often challenging, as it is never normal.

• Pylorospasm is a functional obstruction in the outlet part of the stomach.

• Pylorospasm is, in contrast to hypertrophic pyloric stenosis, a typically non-structural sphincteric obstruction.

• Pylorospasm responds to atropine administration, while hypertrophic pyloric stenosis often requires surgical sphincterotomy.

• Ultrasonography could differentiate between pylorospasm and hypertrophic pyloric stenosis in neonates.

Case presentation

A male 6-day-old premature neonate of 33 gestational weeks, born via cesarean section and surrogacy to Iraqi parents, was referred to the pediatric surgery department with the complaint of intermittent emesis of ingested milk for 4 days, with an initial diagnosis of IHPS. At birth, he had an Apgar score of 8/10 and weighed 1300 g. He was placed on nasal synchronized intermittent mandatory ventilation without the administration of external surfactant. The baby was fed from a milk bank. Although the infant’s weight gain was not satisfactory, both diaper wetting and a single bowel movement were within the normal range. At the surgical center, ultrasonography was performed to evaluate the suspected diagnosis; however, no evidence of HPS was detected. Subsequently, the neonate underwent an upper gastrointestinal series, which confirmed the diagnosis of pylorospasm, consistent with the sonographic findings (Fig. 1). The administration of oral atropine sulfate at an initial dose of 0.05 mg/kg/d, as outlined in our protocol, proved effective, resulting in significant clinical improvement and satisfactory weight gain.

Figure 1.

A narrowing in the section of pyloric sphincter 10 minutes after barium contrast gavage representing pylorospasm at the first sight.

Protocol adoption

In our study, we adopted a protocol closely aligned with the method used by Atsuyuki Yamataka and colleagues in their research comparing pyloromyotomy versus atropine sulfate for IHPS, conducted in Tokyo, Japan^[3^].

Initial hospitalization and stabilization

Hydration, electrolyte correction, and maintenance fluids were prioritized upon admission to our institution.

To ensure ongoing care and stabilization, a nasogastric (NG) tube has been inserted.

Oral atropine administration

At our center, we administered atropine orally in an aqueous solution, starting with an initial dose of 0.05 mg/kg/day.

The total daily dose was divided into eight equal doses, each 1 mL.

Prior to administering each dose of atropine, gastric decompression was conducted, and the infant was positioned in a right-side-down posture for 15–30 minutes post-dose.

Monitoring and adjustment

A careful observation of vomiting was conducted, allowing for the re-administration of atropine and feeding as needed.

We adjusted the atropine dose individually until the patient demonstrated the ability to tolerate oral feeding twice daily.

The oral atropine dose was increased incrementally, reaching a maximum of 0.1 mg/kg/day.

Transition to intravenous atropine

If oral atropine proves ineffective by the third day, we consider transitioning to intravenous administration.

The administration of intravenous atropine was started at a dosage equivalent to half of the maximum oral dose and was gradually increased up to 0.1 mg/kg per day.

Hospitalization and parental education

Continued hospitalization was ensured until full feeding could be maintained with oral atropine.

A comprehensive educational session was conducted for parents on the administration of atropine, with particular emphasis on adhering to our established protocol for accurate dosing.

Pyloric muscle normalization and dosage reduction

The treatment continued until the pyloric muscle thickness normalized on ultrasound.

We gradually reduced the atropine dose after normalization.

Night shift protocol

With no increase, we maintained the atropine concentration and oral feed amounts constant throughout the night shift (12 a.m. to 6 a.m.).

If vomiting occurs, we reduce the oral feed volume until the next day. Regular stomach decompression via the NG tube is performed between feeds.

Post-discharge monitoring

Following discharge, monthly ultrasounds were performed with the purpose of observing variations in the thickness of the pyloric muscle.

In our case, the utilization of oral atropine sulfate did not result in any reported side effects.

On the third day, the therapeutic effects of atropine became evident, with a decrease in vomiting frequency (less than twice per day). Furthermore, by day 7, our patient exhibited full feeding (at a rate of 120 mL/kg/day) with no episodes of vomiting.

Atropine treatment was prolonged until an ultrasound confirmed a return to normal pyloric muscle thickness (3.5 mm), a process that lasted approximately 2.5 months. The summary of events is provided as a timeline (Chart 1).

Discussion

Confronting neonatal vomiting, the forceful extrusion of gastric contents is always serious and often challenging, as it is never normal. True vomiting, the opposite of gastroesophageal reflux and common among neonates, has a prevalence ranging from 11% to 36% in neonatal emergency departments and can be classified as surgical or non-surgical etiologies^[4,5^]. Among the surgical cases, HPS, malrotation with midgut volvulus, intestinal atresia, meconium syndromes, Hirschsprung disease, and incarcerated inguinal hernias are the most significant. Among nonsurgical conditions, sepsis and infection, inborn errors of metabolism, increased intracranial pressure, necrotizing enterocolitis, and feeding intolerance are the most common^[6^]. The composition of the pylorus includes an inner circular muscle layer of greater thickness and an outer longitudinal layer of lesser thickness. HPS is characterized by marked hypertrophy and hyperplasia of the circular muscle and, occasionally, the longitudinal muscle, presenting in either a focal or diffuse pattern^[7^]. There are also noted inflammatory and degenerative alterations in the ganglion cells of the myenteric plexus. Therefore, the inability of the elongated pylorus to relax leads to the occurrence of gastric outlet obstruction. The incidence rate is 1 in 250 live births, with a male-to-female ratio of 4:1. An increase in the prevalence of first-born males has been documented^[8^]. While the association with HPS is commonly noted, it is important to recognize the existence of a significantly less common condition, pylorospasm. In this phenomenon, HPS symptoms are evident in the absence of pyloric muscle hypertrophy, indicating a functional disorder of the pylorus. Just like with HPS, the infant exhibits hunger and will promptly resume eating after vomiting, albeit with potential weight loss as symptoms persist. Since its first use in 1977 for the diagnosis of HPS, ultrasonography has proved to be an important tool^[9^]. Thus far, ultrasonographic measurements and images have been established to define abnormalities and diagnose HPS^[10,11^]. There has been limited discussion in the literature on pylorospasm, particularly regarding its diagnosis and imaging findings. Unlike in the case of HPS, where surgical intervention is necessary, the treatment for pylorospasm is primarily conservative, typically involving the use of antispasmodics or a more passive approach of watchful waiting. A couple of studies by Swischuk et al reported that pylorospasm is a commonly observed condition in infancy; nevertheless, there is typically no pyloric muscle thickening. It has been advised that caution should be exercised when imaging the contracted canal of pylorospasm tangentially, as it may present an erroneously thickened appearance^[3,12^]. A study comparing imaging features of the two phenomena reported seven cases identified as “pylorospasm or early evolving HPS” among 150 cases sent for sonography to rule out HPS. According to this term, it is possible that a majority, if not all, of these cases could progress into fully developed pyloric stenosis. Among the seven patients studied, gastric emptying was delayed, and pyloric length was elongated, with measurements ranging from 10 to 14 mm. Their muscle wall thickness measurements were between 1.3 and 2.7 mm, which would make diagnostic confusion between pylorospasm and HPS unlikely^[13^]. Another study was conducted by Haran et al. A previous statement outlined the correlation between severe and prolonged pylorospasm and the development of characteristic radiographic signs associated with HPS. Additionally, it was proposed that an extended fluoroscopy duration during an upper gastrointestinal tract series could aid in distinguishing between pylorospasm and HPS^[14^]. In a 1998 systematic review, the objective was to compare HPS and pylorospasm using imaging techniques. The authors regarded pylorospasm as a simulator of HPS and stated that extended imaging can assist in distinguishing between the two. From their perspective, sonographic studies would not be sufficient to dispel concerns about radiation exposure^[15^].

Conclusion

Our case report illuminates the clinical nuances of pylorospasm, underscoring its distinct features from HPS. This study highlights the significance of precise diagnostic evaluations and personalized treatment approaches for neonatal gastrointestinal disorders.

Ethical approval

This issue has been raised and approved by the Ethics Committee of Ardabil University of Medical Sciences, Iran.

Consent

The consent in which the patient has allowed the use of medical records and therapeutic information is attached to the medical document. The authors testify to the maintenance of patient privacy. Upon request, a copy of the written consent is available for review by the Editor-in-Chief of this journal.

The authors ensure that all the images, figures, and photos are suitably anonymized, with no patient information or means of identifying the patient.

Sources of funding

None.

Author contributions

Ali Samady Khanghah (A.S.K.): Writing – Original Draft. Abbas Boskabadi (A.B.): Writing – Review & Editing; Supervision. Mahdi Parvizi Mashhadi (M.P.M.): Writing – Review & Editing; Supervision. Gholamreza Ebrahimisaraj (G.E.): Writing – Review & Editing; Supervision. Khashayar Atqiaee (K.A.): Validation; Supervision.

Conflicts of interest disclosure

The authors declare there are no conflicts of interest.

Registration unique identifying number (UIN)

This manuscript is a retrospective case report describing the clinical management of a single patient following established institutional protocols. As it is an observational report of standard clinical practice and not a prospective experimental study or clinical trial, it was not registered in a public database prior to treatment. However, we have ensured full compliance with the SCARE 2025 guidelines.

Guarantor

The corresponding author accepts full responsibility for the work and approves the entire process, from study design through to publication.

Provenance and peer review

Not commissioned; externally peer-reviewed.

Acknowledgements

Not applicable.