# Routine post-operative full blood count assessment is not necessary in elective hip and knee arthroplasty: A prospective cohort study

## TL;DR

This study shows that routine blood tests after hip and knee replacement surgeries are unnecessary and do not improve patient outcomes.

## Contribution

The study demonstrates that routine post-operative haemoglobin monitoring does not reduce complications and is not cost-effective.

## Key findings

- Only 0.8% of patients required blood transfusions despite a mean haemoglobin drop of 2.1 g/dL.
- 21.9% of patients had outpatient surgery with no readmissions or complications within 90 days.
- Routine haemoglobin monitoring is costly and does not provide actionable information.

## Abstract

Hip and knee arthroplasty are among the commonest orthopaedic procedures performed worldwide and can be associated with significant blood loss. Routine haemoglobin sampling increases transfusion rates without an overall reduction in morbidity and mortality, yet providers commonly adopt an absolute numerical value as warranting transfusion post-operatively. Our aim was to establish what proportion of patients had a significant reduction in haemoglobin requiring transfusion thus assessing the necessity of routine post-operative haemoglobin assessment in an inpatient and outpatient patient cohort undergoing total joint replacement.

We performed a review of prospectively collected data in an institutional database of all primary elective hip and knee arthroplasty cases performed by a single surgeon at an urban tertiary referral centre from 2018 to 2023. We assessed pre-operative and post-operative variables amongst patients to identify predictors for transfusion following surgery. All statistics were performed using Stata release 17.

490 elective primary hip or knee arthroplasty procedures were performed within the six year period of which the mean drop in haemoglobin was 2.1 g/dL (SD 1.0, Range −5.6 to +1) post-operatively. Four patients (0.8 %) had a haemoglobin drop below 8 g/dL and 19 (3.9 %) had a level below 9 g/dL, however only 4 patients (0.8 %) required allogenic blood transfusion. One hundred and six patients (21.9 %) underwent day-case arthroplasty of which there was no re-admissions or complications within 90 days of surgery.

The routine monitoring of haemoglobin following elective TJA is costly and unnecessary whilst not contributing to actionable information. We recommend that patients with a pre-operative level greater than 11 g/dL may not require routine post-operative full blood count as mean drop in haemoglobin of less than 3 g/dL can be expected. We continue to advocate that day-case arthroplasty is safe in appropriately selected patients as defined by ASA grade at anaesthetic pre-assessment.

Level II – Prospective cohort study.

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•Routine haemoglobin sampling increases transfusion rates without an overall reduction in morbidity and mortality.•490 elective primary hip or knee arthroplasty procedures were performed within the six year period of which the mean drop in haemoglobin was 2.1 g/dL.•0.8 % had a haemoglobin drop below 8 g/dL and 3.9 % had a level below 9 g/dL, only 4 patients (0.8 %) required allogenic blood transfusion.•106 (21.9 %) underwent day-case arthroplasty of which there was no re-admissions or complications within 90 days of surgery.•The routine monitoring of haemoglobin following elective TJA is a costly unnecessary endeavour and does not contribute to actionable information.

Routine haemoglobin sampling increases transfusion rates without an overall reduction in morbidity and mortality.

490 elective primary hip or knee arthroplasty procedures were performed within the six year period of which the mean drop in haemoglobin was 2.1 g/dL.

0.8 % had a haemoglobin drop below 8 g/dL and 3.9 % had a level below 9 g/dL, only 4 patients (0.8 %) required allogenic blood transfusion.

106 (21.9 %) underwent day-case arthroplasty of which there was no re-admissions or complications within 90 days of surgery.

The routine monitoring of haemoglobin following elective TJA is a costly unnecessary endeavour and does not contribute to actionable information.