Is There a Clinical Benefit for Routine Post-Operative Blood Tests in Patients Undergoing Elective Robotic Assisted Laparoscopic Prostatectomy?

Introduction

Robotic Assisted Radical Prostatectomy (RALP) surgeries are an increasingly common elective urological surgical procedures in the management of localised prostate cancer, and have become the standard of care worldwide at many centres replacing open radical prostatectomies.¹ Between 2017-2019, 24,871 radical prostatectomies were performed in England under NHS funding, of which 89% were robotic-assisted.²

Advantages of robotic laparoscopic approach include smaller surgical incision, decreased post-operative pain, reduced analgesic requirement, less operative blood loss and shortened hospital stay, when compared to open or laparoscopic approaches.¹ Despite the lower complication rates, post-operative blood tests are frequently requested following RALP surgeries, regardless of the clinical necessity.

At the institution in which this study was undertaken (Lister Hospital, Stevenage), it is a standard practice for patients who have undergone RALP surgery to be admitted overnight and to have routine post-operative blood tests, including a Full Blood Count (FBC), C-reactive protein (CRP) and Urea & Electrolytes (U&Es). The practice of obtaining routine post-operative blood tests is one that is firmly embedded within the healthcare system, with minimal clinical justification.3 This privilege tends to abuse with over testing and inappropriate use of resources, unless conducted based on intraoperative circumstances. In this retrospective study, we therefore investigated whether there is a clinical benefit and value to routine post-operative blood testing following RALP surgery.

Materials and Methods

Study Design

A single-centre, multi-surgeon study was conducted. The data included pre- and post-operative blood tests of all patients who underwent RALP surgeries at Lister Hospital between February 2016 and February 2018. Pre- and post-operative blood tests had to include a FBC, CRP, and U&Es, with the study looking specifically at Haemoglobin (Hb), White Cell Count (WCC), CRP and Creatinine levels. Where any of the specified data was absent, the patient was discounted from the study.

Data analysis and statistics

Statistical analysis was performed using Microsoft Excel. Results are presented as a mean ± SD. A paired t test was administered to determine if the results were statistically significant.

Results

Subjects

Three hundred eighty-three patients underwent RALP surgeries at Lister Hospital between February 2016 and February 2018. The patients underwent a routine preoperative assessment, on an average, six days prior to surgery. Fifty-three of these patients did not have the required complete set of blood results, and were hence discounted from the study. Thus a final sample of 330 patients was included. The mean age of the cohort was 62 years (Range 44-84 years).

Blood results

There was a statistically significant difference between pre- and post-operative blood tests for all four parameters that were measured (Table 1). Figure 1 shows the change in blood parameters postoperatively.

Haemoglobin

There was an average Hb loss of 22.4 g/L with a maximum drop of 56 g/L. No patients had a Hb below 80 g/L, which would necessitate transfusion (Figure 1).

White Cell Count

The white cell count was raised by an average of 4.1x109 /L. Nineteen patients had a total white cell count above 16x109 /L post op (Figure 1).

CRP

The average rise of CRP was 28 and the maximum rise was 206 (Figure 2).

Creatinine

A small but significant rise in creatinine was seen 4.6 mmol/L. We defined Acute kidney injury (AKI) stage 1, 2 and 3 as 1.5, 2- and 3-times pre-op creatinine, respectively. Two patients developed AKI stage 1, one patient developed AKI stage 2 and none of the patients developed AKI stage 3 (Figure 2).

Discussion

Robotic assisted radical prostatectomy is increasingly becoming the standard of care for the management of localised prostate cancer. With the advances in surgery and enhanced recovery, most patients are being discharged within one or two days of the operation. Patel and colleagues demonstrated the mean length of stay (LOS) as 1.17 days in RALP patients and 97.5% of these patients were discharged on or before postoperative day 1.³ Performing routine post-operative blood tests has become the norm after major pelvic surgeries. With minimally invasive surgery, more accurate blood loss measurement and enhanced recovery, we aimed to analyse if routine post-operative blood tests are really required.

With the majority of radical prostatectomies being performed using robotic assistance rather than open approach, the risk of blood loss is markedly reduced due to better visualisation that enables precise haemostasis and the addition of venous compression caused by increased abdominal pressure.⁴ The metaanalysis by Parsons and Bennett, revealed that patients undergoing robotic prostatectomy were 77% less likely to receive blood transfusion when compared to patients undergoing open surgery.⁵ According to the BAUS Radical Prostatectomy analysis of 2017, 6,852 robotically-assisted prostatectomies were done out of a total of 7,962 radical prostatectomies. Of these RALPs performed, only 12 patients were transfused, equating to 0.18% transfusion rate or 1 in every 550 patients.⁶ In our retrospective analysis, none of the patients required a post op blood transfusion. With these low transfusable post-operative anaemia rates, it is difficult to justify routine post-op Hb checks unless there was deemed to be substantial intra-operative bleeding or clinical suspicion of a post-operative bleed.

CRP is the most used biomarker to help diagnose and monitor infection, particularly sepsis.⁷ Major abdominal surgery expectedly causes inflammation and a stress response that will result in an iatrogenic rise in CRP, thus making it difficult to interpret CRP results. Santonocito et al., measured CRP for seven days post-op in both non-infected and post-operatively infected patients.⁸ It was demonstrated that for patients who underwent abdominal, neurological and cardiac surgeries, there was a similar rise in CRP up to day 4. The CRP of those in the non-infected group started to decrease, whilst the CRP of those in the infected group continued to rise. This suggests that CRP may be of benefit in identifying postoperative infections beyond day4 , but not immediately after surgery. Other clinical signs such as fever are also difficult to interpret in the context of surgery as fever is accepted up to 48 hours post-surgery. This is due to the systemic inflammatory response syndrome, not mediated by infection but instead generated by tissue damage and cytokine release.⁹ For fevers that extend past 48 hours, an infectious cause should be considered and investigated appropriately.

Unlike transfusable anaemia, post-operative infection is a more common complication. Infection (chest infection, wound infection, systemic sepsis) accounted for 17.28% of complications of radical prostatectomies in 2017.⁶ Due to the pathophysiology of infections, they do not usually present in the acute post-op phase, but usually manifest post discharge requiring readmission. In these cases, CRP can be justified to help assess the severity of infection and also the treatment efficacy.⁸

CRP can also be elevated preoperatively in patients with higher Gleason score on biopsy and RP, extracapsular extension, seminal vesicle invasion and lymph node metastasis.¹⁰ Although CRP has independent prognostic value, it does not add prognostically or clinically significant information to standard predictors of outcomes.

It is known that laparoscopic procedures including RALP can cause transient oliguria. Prolonged intraabdominal pressure of 15-20 mmHg coupled with the Trendelenburg positioning of the patient reduces Glomerular filtration rate (GFR) and renal blood flow causing oliguria. Ahn et al., measured creatinine and creatinine clearance pre- and post RALP in patients with normal renal function and renal impairment.¹¹ No significant change in Cr levels from base line, at 1 day and 30 days post-op was noted. A similar study¹⁰ observed 160 RALPs and compared the creatinine levels pre and 12h post op. On an average, they noted a 5.31 mL/min increase post operatively, which is comparable to the 5.1 mL/min reported from data analysed.¹² These studies indicate that RALP procedures do not routinely induce acute kidney injury and therefore focus should be on good pre, peri and postoperative fluid management to ensure adequate renal perfusion and maintenance of function.

A reduction in routine post-operative blood tests following RALP surgeries would result in a considerable saving. National Institute for Clinical Excellence (NICE) reports the average cost of a FBC and U&E test, taking into account operator time, equipment use and laboratory analysis, to be £12.00.¹³ This amounts to an approximate cost of £4000 for the 330 patients identified in this study. If routine post-operative blood tests were to be omitted, this would represent a significant saving for the Trust. Further financial benefit could be observed taking into consideration prolonged period of admission waiting for sampling and analysis of blood. Thus, improvement in patient flow and decrease in rates of delayed discharge can be achieved by avoiding unnecessary blood tests.

Infection risk and patient factors

• Reduced trauma to the patient
• Reduced infection risk
• Reduced work-load for phlebotomists

Conclusion

We demonstrated that routine post-operative blood testing following RALP surgeries has limited clinical benefit, is labour-intensive and utilises considerable resources. The necessity of routine post-operative blood tests following elective RALP surgeries is called into question for operations with no intraoperative concerns.

A patient-specific approach should be taken with regards to post-operative blood tests, considering intra-operative factors and clinical need to avoid unnecessary testing. The use of routine post-operative blood tests is one that is firmly embedded into the healthcare system, with minimal clinical justification. With a push for Enhanced Recovery After Surgery (ERAS) protocols, there is likely to be a further shift of RALP surgeries becoming day-case procedures, which is already in practice at certain centres in UK. This further reinforces the value of clinical judgement of the surgeon as to whether postoperative blood testing and overnight stays are required, given the low complication rates associated with RALP surgeries.

Conflict of Interest

None