Diagnostic accuracy of CRP/albumin and neutrophil/lymphocyte ratios for early detection of staple line leak after laparoscopic sleeve gastrectomy in high-risk patients: a prospective observational study

Abstract

Background & objective: Early detection of staple-line leak (SLL) after laparoscopic sleeve gastrectomy (LSG) is important for prompt intervention and to reduce the morbidity and mortality of this group of patients. We evaluated neutrophil-to-lymphocyte ratio (NLR) and C-reactive protein/albumin ratio (CAR) for early detection of staple-line leak (SLL) after laparoscopic sleeve gastrectomy (LSG) in high-risk patients.

Methodology: This prospective diagnostic study was carried out at Ain Shams University Hospitals, from Aug 2022 to Jul 2023. Fifty adult patients with a BMI >50 kg/m², ASA III, who  had undergone LSG, had CBC, CRP, and albumin measured preoperatively and on postoperative days (POD) 1–3; NLR and CAR were calculated. To confirm the presence of SLL required two positive abdominal ultrasounds. ROC analyses estimated AUC, optimal cut-offs, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) , and accuracy.

Results: SLL occurred in 5/50 (10%), diagnosed at 11.8 ± 3.5 days. Baseline markers were similar (all P > 0.17). On POD1–3, CRP, CAR, and NLR were higher with SLL (all P < 0.001); albumin was lower on POD3 (P < 0.001). NLR performed best: POD1 cutoff ≥2.6—AUC 0.78, sensitivity 60%, specificity 100%, accuracy 96%; POD2 ≥3.1—AUC 0.94, sensitivity 80%, specificity 100%, accuracy 98%; POD3 ≥3.5—AUC 1.00 with 100% sensitivity, specificity, and accuracy. On POD3, CRP ≥8.1 (AUC 0.91) and CAR ≥2.16 (AUC 0.95) were inferior.

Conclusion: In high-risk LSG, serial NLR—especially by POD3—provides near-perfect discrimination of SLL and outperforms CRP and CAR. Routine NLR monitoring may expedite diagnosis and intervention.

Abbreviations: AUC: Area under curve, CRP: C-reactive protein, CAR: C-reactive protein/albumin ratio, CBC: Complete blood count, NLR: neutrophil-to-lymphocyte ratio, POD: Postoperative day, SLL: staple-line leak, 

Keywords: Staple Line Leak, Neutrophil-to-Lymphocyte Ratio, Laparoscopic Sleeve Gastrectomy, CRP/Albumin Ratio, Bariatric Surgery.

Citation: Eid SM, Eldin AE, Khamis AM, Mohamed MIH. Diagnostic accuracy of CRP/albumin and neutrophil/lymphocyte ratios for early detection of staple line leak after laparoscopic sleeve gastrectomy in high-risk patients: a prospective observational study. Anaesth. pain intensive care 2026;30(2):232-239. DOI: 10.35975/apic.v30i2.3131

Received: May 09, 2025; Revised: October 26, 2025; Accepted: January 01, 2026