Association of Preoperative Sodium Abnormalities With Postoperative Complications in Gynecologic Surgery

INTRODUCTION: Abnormal preoperative sodium levels have been associated with poor postoperative outcomes in multiple surgical specialties, including orthopedics, cardiac surgery, and gynecology oncology. There currently are no published studies examining whether abnormal preoperative sodium levels are associated with postoperative complications in benign gynecologic surgery. OBJECTIVE: To evaluate the relationship between abnormal sodium levels and postoperative complications in patients undergoing elective, benign gynecologic surgery. METHODS: Data from the 2019–2023 National Surgical Quality Improvement Program (NSQIP) were analyzed using Current Procedural Terminology (CPT) codes for gynecologic surgeries, including hysterectomy, hysteroscopy, prolapse repair surgeries, incontinence procedures, myomectomies, abdominal and laparoscopic adnexal surgeries, and minor gynecologic procedures. Patients undergoing a non-elective procedure or who had a pregnancy-related or oncologic postoperative diagnosis were excluded. Hyponatremia was defined as sodium level less than 135, and hypernatremia was defined as sodium above 145. Chi-squared tests and t-tests were performed using Stata 12. RESULTS: A total of 223,050 patients who underwent elective, benign gynecologic surgery were identified with recorded preoperative sodium values, within which 6,238 patients had hyponatremia (2.8%) and 707 patients had hypernatremia (0.32%). Patients with preoperative sodium derangements were more likely to be older (normal, 49.2±13.1; hyponatremia, 52.4±15.7, p=<0.001; hypernatremia, 57.0±13.5, p=<0.001), to have chronic obstructive pulmonary disease (normal, 1.1%; hyponatremia, 2.1%, p=<0.001; hypernatremia, 3.1%, p=<0.001), hypertension (normal, 31.2%; hyponatremia, 44.3%, p=<0.001; hypernatremia, 40.6, p=<0.001), and have a higher ASA class (p<0.001 for hyponatremia and hypernatremia). Patients with sodium derangements had a higher estimated probability of morbidity and higher estimated probability of mortality (p=<0.001 for hyponatremia and hyponatremia). Patients with hypernatremia were more likely to unplanned reintubation (0.42% vs 0.06%, p=<0.001) and be diagnosed with pneumonia (0.85% vs 0.14%, p=0.001) than patients with normal sodium; patients with both hypo- and hypernatremia had higher rates of prolonged intubation than patients with normal sodium (normal, 0.04%; hyponatremia, 0.16%, p=<0.001; hypernatremia, 0.71, p=<0.001). Patients with hyponatremia were more likely to suffer acute renal failure in the postoperative period (0.08% vs 0.01%, p=<0.001) or to have a cardiac arrest (0.13% vs 0.03%, p=<0.001). Both hyponatremia and hypernatremia were associated with elevated risk of septic shock (normal, 0.08%; hyponatremia, 0.29%, p=<0.001; hypernatremia, 0.85%, p=<0.001). Hyponatremia was associated with higher rate of unplanned readmission within 30 days (3.64% vs 2.49%, p=<0.001), unplanned reoperation within 60 days (1.73% vs 1.18%, p=0.001), and a longer hospital stay (1.2 ± 4.2 days vs 0.9 ± 2.6 days, p=<0.001). CONCLUSIONS: Preoperative sodium derangements are associated with postoperative complications for benign gynecologic surgeries. Preoperative sodium levels can be used to stratify patients who are at a higher risk of postoperative complication, and patients with preoperative sodium abnormalities may require additional preoperative optimization.Table 1Table 2