The Utility of Obtaining Routine Hematologic Laboratory Values Following a Minimally Invasive Transforaminal Lumbar Interbody Fusion

Presented at SMISS Annual Forum 2014
By Abbas Naqvi BS
With Kern Singh MD, Islam Elboghdady , Eric Sundberg MD, Hamid Hassanzadeh MD, Anton Jorgensen MD, Khaled Aboushaala MD, Blaine Manning BS,

Disclosures: Abbas Naqvi BS None Kern Singh MD A; CSRS Resident Grant. B; DePuy, Zimmer, Stryker, CSRS, ISASS, AAOS, SRS, Vertebral Column - ISASS. D; Avaz Surgical, LLC, Vital 5, LLC. F; Zimmer, Stryker, Pioneer, Lippincott Williams & Wilkins, Th, Islam Elboghdady None, Eric Sundberg MD None, Hamid Hassanzadeh MD None, Anton Jorgensen MD None, Khaled Aboushaala MD None, Blaine Manning BS None,

Introduction:
Despite the minimal blood loss and morbidity associated with a MIS TLIF, many institutions obtain routine postoperative hematologic values including a complete blood count (CBC) and basic metabolic panel (BMP). The utility of these tests has not been well characterized in the literature.

Aims/Objectives:
To characterize the utility of obtaining routine postoperative hematologic laboratory values following a minimally invasive (MIS) transforaminal lumbar interbody fusion (TLIF).

Methods:
A retrospective analysis of 334 patients who underwent a single-level MIS TLIF for degenerative lumbar spine pathology between 2007-2013 was performed. Patient demographics, comorbidities identified utilizing the Charlson Comorbidity Index (CCI), smoking status, pre- and postoperative Visual Analogue Scores (VAS), procedural time, estimated blood loss (EBL), hospital length of stay (LOS), complications, transfusion volumes, and the need for electrolytes replacement were assessed. The patient’s postoperative hemoglobin, hematocrit, glucose, blood urea nitrogen (BUN), creatinine, sodium, potassium, chloride, and calcium were compared to preoperative values. Statistical analysis was performed utilizing Paired-Samples T tests. An alpha level of ≤0.05 denoted statistical significance.

Results:
A total of 334 single-level MIS TLIF procedures were identified. The mean age of the cohort was 50.4±12.6 years. The overall mean procedural time, EBL, and LOS were 123.3±39.6 minutes, 79.06±82.6 cc, and 64.8±29.9 hours, respectively. Overall, 94.0% of patients demonstrated radiographic arthrodesis at 1-year confirmed via computed tomograhy. Following a MIS TLIF, the postoperative hemoglobin, hematocrit, BUN, creatinine, sodium, potassium, and calcium statistically decreased while glucose increased when compared to the preoperative values (p<0.05). None of the patients in both cohorts required intraoperative or postoperative blood product transfusion, while 15 (4.5%) patients required postoperative potassium replacement for asymptomatic laboratory values.

Conclusions:
The majority of MIS TLIF procedures did not require any action to be taken based upon the patient’s routine postoperative hematologic laboratory data. Despite statistically significant lower postoperative hemoglobin and hematocrit levels compared to preoperative values, none of the patients required blood product transfusions. These findings suggest that there may be little utility in obtaining routine postoperative complete blood counts or basic metabolic panels following an uncomplicated MIS TLIF unless significant intraoperative bleeding is noted or the patient carries risk factors for cardiac disease, renal dysfunction or postoperative anemia.