Early Kidney Injury Biomarkers in Gynecologic Laparoscopic Surgery

This single-center, prospective observational study aims to evaluate the effects of pneumoperitoneum and Trendelenburg positioning on early renal tubular injury during elective gynecological laparoscopic surgery. Although laparoscopic surgery provides well-established surgical benefits, carbon dioxide pneumoperitoneum combined with prolonged Trendelenburg positioning may reduce renal perfusion through alterations in intra-abdominal pressure and systemic hemodynamics. Conventional assessment of renal function relies primarily on serum creatinine, which may not increase until substantial nephron injury has occurred, limiting the early detection of subclinical acute kidney injury (AKI).

Adult patients scheduled for elective gynecological laparoscopic procedures with an anticipated operative duration of at least 90 minutes will be screened for eligibility. To minimize perioperative variability, anesthetic management, intraoperative fluid therapy, and perioperative care will be standardized for all participants according to the Enhanced Recovery After Surgery (ERAS) recommendations. Intra-abdominal pressure will be maintained within the routine clinical range of 12-14 mmHg throughout the procedure.

Participants will be allocated into two cohorts according to the Trendelenburg angle required for the planned surgical procedure: a 30° Trendelenburg group and a 45° Trendelenburg group. No intervention regarding patient positioning will be performed for study purposes, and group allocation will be based solely on routine surgical practice.

Urine samples will be collected at predefined time points: after induction of anesthesia and urinary catheterization (baseline) and at the sixth postoperative hour. Urinary neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1) concentrations will be measured using enzyme-linked immunosorbent assay (ELISA). To reduce the influence of urine dilution and hydration status, biomarker concentrations will be normalized to urinary creatinine and expressed as NGAL/creatinine and KIM-1/creatinine ratios.

The study sample size was determined by power analysis, with a target enrollment of 50 participants. Statistical analyses will evaluate perioperative changes in urinary NGAL/creatinine and KIM-1/creatinine ratios between baseline and the postoperative period. Biomarker changes will be compared between the 30° and 45° Trendelenburg groups and analyzed in relation to the duration of pneumoperitoneum.

This study aims to determine whether perioperative changes in urinary NGAL and KIM-1 are associated with the degree of Trendelenburg positioning and the duration of pneumoperitoneum during gynecological laparoscopic surgery. The findings are expected to improve the understanding of early renal tubular stress associated with laparoscopic surgery and provide preliminary evidence for future studies investigating strategies to preserve renal function during minimally invasive surgical procedures.

Inclusion criteria

Female participants aged 18 years or older. Scheduled for elective gynecological laparoscopic surgery. Expected duration of pneumoperitoneum of at least 90 minutes. Planned intraoperative Trendelenburg position of approximately 30° or 45°. Ability to provide written informed consent. -

Exclusion criteria

Age younger than 18 years. Pre-existing chronic kidney disease (estimated glomerular filtration rate <60 mL/min/1.73 m² or serum creatinine above the institutional upper limit of normal).

Acute kidney injury before surgery. History of kidney transplantation or renal replacement therapy. Active urinary tract infection. Pregnancy. Conversion from laparoscopic to open surgery. Intraoperative conditions requiring major deviation from the standardized anesthetic or surgical protocol.

Inability to provide written informed consent.

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