Objective The aim of this study was to assess the incidence of and risk factors for hypomagnesemia in patients undergoing gynecologic surgery by a gynecologic oncologist.

Methods A retrospective chart review was performed on all patients undergoing surgery for gynecologic pathology from July 2011 to July 2015 by a single surgeon. Demographic data, surgical indication, surgery performed, preoperative laboratory values, postoperative laboratory values, and medical history were examined. Hypomagnesemia was defined as less than 1.8 mg/dL. Hypermagnesemia was defined as greater than 2.5 mg/dL.

Results Six hundred sixty-nine patients were identified for analysis. One hundred ninety-seven patients had hypomagnesemia (29.4%). Four hundred sixty-six patients had normal magnesium levels (69.5%), and 6 patients had hypermagnesemia (1%). Among patients with benign disease, 24.9% had preoperative hypomagnesemia compared with 32.7% of patients with a gynecologic malignancy. African American race (P = 0.041), diabetes mellitus (P < 0.001), and malignancy (P = 0.029) were all associated with preoperative hypomagnesemia. Diabetes and major surgery were associated with postoperative hypomagnesemia (P = 0.012 and P = 0.048, respectively). Hypomagnesemia was associated with increased preoperative and postoperative pain (P = 0.049 and P < 0.001, respectively) as well as postoperative hypokalemia (P = 0.001). Age, body mass index, hypertension, cancer type, hematocrit, surgical indication, and length of hospital stay were not associated with hypomagnesemia.

Conclusions Perioperative hypomagnesemia is prevalent in patients undergoing gynecologic surgery by a gynecologic oncology, especially in patients who have a gynecologic malignancy. We recommend routine preoperative and postoperative evaluation of serum magnesium in all patients undergoing gynecologic surgery by a gynecologic oncologist.