In cases of hypertrophic pyloric stenosis (HPS), the transverse muscle must measure greater than what?

In hypertrophic pyloric stenosis (HPS), the diagnosis is often confirmed through ultrasound findings that assess the thickness of the pyloric muscle. The key measurement of the transverse muscle, specifically the pyloric muscle wall thickness, is traditionally considered to be significant when it exceeds 4 mm. This threshold indicates that the muscle is hypertrophied, contributing to the characteristic narrowing of the pylorus, which can lead to obstruction.

When the transverse muscle's thickness is greater than 4 mm, it often correlates with clinical symptoms and imaging findings consistent with HPS. This measurement is crucial in differentiating affected patients from those with normal pyloric structure, thus aiding in timely diagnosis and management of the condition.

Accordingly, while measurements below this threshold might not definitively indicate hypertrophic pyloric stenosis, a thickness greater than 4 mm strongly supports the diagnosis, making it a pivotal measurement in clinical practice.