Defining normal neonatal abdominal wall musculature with ultrasonography

The development of new surgical approaches for the management of congenital abdominal wall defects may be facilitated by using an animal model. However, because the anatomy of the neonatal abdominal wall has not been described, a suitable model is yet to be identified. We aimed to evaluate and define the neonatal abdominal wall musculature using ultrasound, to be used as a reference to identify an appropriate animal model for the neonatal abdominal wall in the future.

Infants with a postconceptual age of less than one month weighing between 2 and 3 kg were eligible. With ethical approval, ultrasonography of three abdominal wall locations bilaterally was performed. The depth of the skin to external oblique and the thickness of the three abdominal wall muscles, external oblique (EO), internal oblique (IO) and transversus abdominis (TA), were measured.

Ten males and seven females were recruited with median postconceptual age of 36 weeks (IQR 36-38), median postnatal age of 8 days (IQR 3-30) and median weight of 2.35kg (IQR 2.26-2.56). The mean depth of EO from skin was 2.06 mm (± 0.44). The mean thicknesses of the muscles were: EO 1.02 mm (± 0.33), IO 1.16 mm (± 0.39) and TA 1.02 mm (± 0.37). There was no statistical difference between the thickness of EO, IO or TA (p= 0.43).

It is possible to consistently identify and measure the components of the neonatal abdominal wall musculature with ultrasonography. We hope this can aid in developing an appropriate animal model, with the ultimate aim of facilitating innovation in surgical management of neonatal abdominal wall pathology.

Study of Diagnostic test, Level IV.