Ultrasound assessment of abdominal wall muscle thickness in liver transplant recipients and healthy donors: a comparative study for the assessment of sarcopenia.

Abstract

Aim: Sarcopenia is a significant predictor of postoperative morbidity and mortality in liver transplant recipients. Traditional assessment tools such as computed tomography (CT) and bioelectrical impedance analysis have limitations in clinical use. This study aimed to evaluate the utility of ultrasonography (USG) in assessing abdominal muscle thickness as a marker of sarcopenia.

Material and methods: This prospective observational study was conducted at a tertiary liver transplant center between September 2023 and May 2024. USG was used to measure the thickness of the external oblique (EO), internal oblique, and transversus abdominis (TA) muscles in 41 liver transplant recipients and 41 healthy donors. Sarcopenia was also assessed using CT-based L3 skeletal muscle index (L3-SMI) and hand grip strength. Correlations with disease severity (Model for End-Stage Liver Disease, Child-Turcotte-Pugh (CTP)), postoperative outcomes, and ascitic fluid volume were analyzed.

Results: Abdominal muscle thickness was significantly lower in recipients compared to donors (EO: 2.9 ± 1.0 mm vs. 4.5 ± 1.8 mm; TA: 2.2 ± 0.7 mm vs. 3.2 ± 1.0 mm; p <0.001). Sarcopenia prevalence was 78% by L3-SMI and 82.9% by hand grip strength. ROC analysis demonstrated that EO <3.6 mm and TA <2.55 mm predicted sarcopenia in males with high sensitivity and specificity. Muscle thinning correlated with higher CTP scores, greater ascitic fluid volume, and prolonged intensive care unit stay.

Conclusions: USG-derived abdominal muscle thickness, especially EO <3.6 mm and TA <2.55 mm in males, is a reliable, non-invasive marker for sarcopenia in liver transplant candidates. It correlates with disease severity and postoperative morbidity, supporting its utility in pre-transplant risk stratification.