Peroperative administration of tranexamic acid in Roux-en-Y and one-anastomosis gastric bypass to reduce haemorrhage in patients with morbid obesity: protocol for randomised controlled trial (PATRY trial).

INTRODUCTION: By implementation of Enhanced Recovery After Bariatric Surgery protocols and day-care surgery, early discharge poses a challenge if excessive bleeding occurs after bariatric surgery. Tranexamic acid (TXA) has demonstrated efficacy in other surgical fields and in bariatric pilot studies. This trial aims to assess the efficacy of peroperative administration of TXA in reducing haemorrhage in patients undergoing gastric bypass surgery. METHOD AND ANALYSIS: This is a multicentre, phase III, double-blind randomised controlled trial in six high-volume bariatric centres in the Netherlands. A total of 1524 eligible patients, aged 18 years or older, undergoing primary gastric bypass surgery (either Roux-en-Y gastric bypass or one-anastomosis gastric bypass) will be randomised between TXA and placebo (1:1, variable block, stratified for centre, day-care/overnight stay and type of surgery) after obtaining informed consent (2.5% less haemorrhage, power 80%, 2-sided-α 0.05 and 10% dropout). Exclusion criteria are pregnancy, amedical history of acute bleeding (without cause), venous thrombotic events (VTEs), epilepsy, anticoagulant use and iatrogenic bleeding during surgery (aside from staple line). The primary outcome is postoperative haemorrhage requiring intervention within 30 days postoperatively. Secondary outcome measures are staple line reinforcement, blood loss, duration of surgery, postoperative haemoglobin, vital parameters, minor and major complications, side effects of TXA (nausea, hypotension and VTE), length of hospital stay and directly made costs. ETHICS AND DISSEMINATION: Written informed consent will be obtained from all participants. The protocol has been approved by the Medical Research Ethics Committees United, Nieuwegein, on 7 February 2023 (registration number: R22.102). Results will be disseminated through peer-reviewed publications and conferences. TRIAL REGISTRATION NUMBER: NCT05464394.

Risk factors for delayed colorectal postpolypectomy bleeding: a meta-analysis.

BACKGROUND: To systematically analyze risk factors for delayed postpolypectomy bleeding (DPPB) in colorectum. METHODS: We searched seven large databases from inception to July 2022 to identify studies that investigated risk factors for DPPB. The effect sizes were expressed by relative risk (RR) and 95% confidence interval (95% CI). The heterogeneity was analyzed by calculating I2 values and performing sensitivity analyses. RESULTS: A total of 15 articles involving 24,074 subjects were included in the study. The incidence of DPPB was found to be 0.02% (95% CI, 0.01-0.03), with an I2 value of 98%. Our analysis revealed that male sex (RR = 1.64), history of hypertension (RR = 1.54), anticoagulation (RR = 4.04), polyp size (RR = 1.19), polyp size ≥ 10 mm (RR = 2.43), polyp size > 10 mm (RR = 3.83), polyps located in the right semicolon (RR = 2.48) and endoscopic mucosal resection (RR = 2.99) were risk factors for DPPB. CONCLUSIONS: Male sex, hypertension, anticoagulation, polyp size, polyp size ≥ 10 mm, polyps located in the right semicolon, and endoscopic mucosal resection were the risk factors for DPPB. Based on our findings, we recommend that endoscopists should fully consider and implement effective intervention measures to minimize the risk of DPPB.

Effect of Tranexamic Acid on Intra- and Postoperative Bleeding in Eyelid Surgery: A Prospective, Randomized, Multicenter, Double-Masked, Control Trial.

PURPOSE: Pilot studies suggest that waiting 15 minutes after a subcutaneous tranexamic acid injection is associated with decreased intraoperative bleeding and postoperative ecchymosis in eyelid surgery. The outcomes of commencing eyelid surgery immediately after injection without a waiting period remain unexplored. METHODS: This prospective, randomized, multicenter, double-masked, controlled study examined bilateral symmetric upper and/or lower lid blepharoplasty or ptosis repair. Patients received tranexamic acid in 1 eyelid and control in the contralateral eyelid. The surgeon recorded the side with more intraoperative bleeding. Two masked graders evaluated periocular ecchymosis at postoperative day 0 and postoperative week 1 (POW 1) with a 5-point scale. At POW 1, patients reported subjective grading of bruising as increased on 1 side or similar on both sides. Results were analyzed with Wilcoxon signed-rank and sign tests. RESULTS: Of 130 patients, there was less eyelid ecchymosis on the tranexamic side at postoperative day 0 ( p = 0.001) and POW 1 ( p < 0.001). By surgery type, the 69 levator advancement surgeries had significantly less ecchymosis at postoperative day 0 ( p < 0.001) and POW 1 ( p = 0.001), while upper eyelid blepharoplasty, combined upper and lower lid blepharoplasty, and conjunctivomullerectomy trended toward significance. Of 68 patients reporting a POW 1 grading, 69% reported less bruising on the tranexamic side ( p < 0.001). Intraoperative bleeding was not significantly different between sides ( p = 0.930). CONCLUSIONS: Without a postinjection waiting period, subcutaneous tranexamic acid for eyelid surgery significantly decreased postoperative ecchymosis on postoperative day 0 and POW 1 but did not affect intraoperative bleeding. Subcutaneous tranexamic acid was not associated with any complications.

Aetiology and predictors of major bleeding events in patients with heart failure with reduced ejection fraction undergoing percutaneous coronary intervention.

OBJECTIVES: We sought to determine the relationship between the degree of left ventricular ejection fraction (LVEF) impairment and the frequency and type of bleeding events after percutaneous coronary intervention (PCI). DESIGN: This was an observational retrospective cohort analysis. Patients who underwent PCI from 2009 to 2017 were identified from our institutional National Cardiovascular Disease Registry (NCDR) CathPCI database. Patients were stratified by pre-PCI LVEF: preserved (≥50%), mildly reduced (41%-49%) and reduced (≤40%) LVEF. PRIMARY OUTCOME MEASURES: The outcome was major bleeding, defined by NCDR criteria. Events were classified based on bleeding aetiology and analysed by multivariable logistic regression. RESULTS: Among 13 537 PCIs, there were 817 bleeding events (6%). The rate of bleeding due to any cause, blood transfusion, gastrointestinal bleeding and coronary artery perforation or tamponade each increased in a stepwise fashion comparing preserved, mildly reduced and reduced LVEF reduction (p<0.05 for all comparisons). However, there were no differences in bleeding due to asymptomatic drops in haemoglobin, access site haematoma or retroperitoneal bleeding. After multivariable adjustment, mildly reduced and reduced LVEF remained independent predictors of bleeding events (OR 1.36, 95% CI 1.06 to 1.74, p<0.05 and OR 1.73, 95% CI 1.45 to 2.06, p<0.0001). CONCLUSIONS: The degree of LV dysfunction is an independent predictor of post-PCI major bleeding events. Patients with mildly reduced or reduced LVEF are at greatest risk of post-PCI bleeding, driven by an increased need for blood transfusion, major GI bleeding events and coronary artery perforation or tamponade. Pre-PCI LV dysfunction does not predict asymptomatic declines in haemoglobin, access site haematoma or retroperitoneal bleeding.

Postoperative delayed massive bleeding in gastric cancer: a case report.

BACKGROUND: Postoperative delayed bleeding of gastric cancer is a complication of radical gastrectomy with low incidence rate and high mortality. CASE PRESENTATION: This case report presents the case of a 63-year-old female patient of Mongolian ethnicity who was diagnosed with gastric malignancy during a routine medical examination and underwent Billroth's I gastric resection in our department. However, on the 24th day after the surgery, she was readmitted due to sudden onset of hematemesis. Gastroscopy, abdominal CT, and digital subtraction angiography revealed postoperative anastomotic fistula, rupture of the duodenal artery, and bleeding from the abdominal aorta. The patient underwent three surgical interventions and two arterial embolizations. The patient's condition stabilized, and she was discharged successfully. CONCLUSION: Currently, there are no specific guidelines for the diagnosis and treatment of pseudoaneurysms in the abdominal cavity resulting from gastric cancer surgery. Early digital subtraction angiography examination should be performed to assist in formulating treatment plans. Early diagnosis and treatment contribute to an improved overall success rate of rescue interventions.

Risk factors for postoperative bleeding following endoscopic submucosal dissection in early gastric cancer: A systematic review and meta-analysis.

BACKGROUND: Early gastric cancer (EGC) presents a significant challenge in surgical management, particularly concerning postoperative bleeding following endoscopic submucosal dissection. Understanding the risk factors associated with postoperative bleeding is crucial for improving patient outcomes. METHODS: Adhering to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, a systematic review and meta-analysis were conducted across PubMed, Embase, Web of Science, and the Cochrane Library without publication date restrictions. The inclusion criteria encompassed observational studies and randomized controlled trials focusing on EGC patients undergoing endoscopic submucosal dissection and their risk factors for postoperative bleeding. The Newcastle-Ottawa Scale was utilized for quality assessment. The effect size was calculated using random or fixed-effects models based on the observed heterogeneity. We assessed the heterogeneity between studies and conducted a sensitivity analysis. RESULTS: In our meta-analysis, 6 studies involving 4868 EGC cases were analyzed. The risk of postoperative bleeding was notably increased with intraoperative ulcer detection (odds ratio: 1.97, 95% confidence interval [CI]: 1.03-3.76, I2 = 61.0%, P = .025) and antithrombotic medication use (odds ratio: 2.02, 95% CI: 1.16-3.51, I2 = 57.2%, P = .039). Lesion resection size showed a significant mean difference (5.16, 95% CI: 2.97-7.98, P < .01), and longer intraoperative procedure time was associated with increased bleeding risk (mean difference: 11.69 minutes, 95% CI: 1.82-26.20, P < .05). Sensitivity analysis affirmed the robustness of these findings, and publication bias assessment indicated no significant bias. CONCLUSIONS: In EGC treatment, the risk of post-endoscopic submucosal dissection bleeding is intricately linked to factors like intraoperative ulcer detection, antithrombotic medication use, the extent of lesion resection, and the length of the surgical procedure. These interwoven risk factors necessitate careful consideration and integrated management strategies to enhance patient outcomes and safety in EGC surgeries.

The Relationship Between Preoperative International Normalized Ratio and Postoperative Major Bleeding in Total Shoulder Arthroplasty.

INTRODUCTION: This study aimed to assess the relationship between preoperative international normalized ratio (INR) levels and major postoperative bleeding events after total shoulder arthroplasty (TSA). METHODS: The American College of Surgeons National Surgical Quality Improvement Program database was queried for TSA from 2011 to 2020. A final cohort of 2405 patients with INR within 2 days of surgery were included. Patients were stratified into four groups: INR ≤ 1.0, 1.0 < INR ≤ 1.25, 1.25< INR ≤ 1.5, and INR > 1.5. The primary outcome was bleeding requiring transfusion within 72 hours, and secondary outcome variables included complication, revision surgery, readmission, and hospital stay duration. Multivariable logistic and linear regression analyses adjusted for relevant comorbidities were done. RESULTS: Of the 2,405 patients, 48% had INR ≤ 1.0, 44% had INR > 1.0 to 1.25, 7% had INR > 1.25 to 1.5, and 1% had INR > 1.5. In the adjusted model, 1.0 < INR ≤ 1.25 (OR 1.7, 95% CI 1.176 to 2.459), 1.25 < INR ≤ 1.5 (OR 2.508, 95% CI 1.454 to 4.325), and INR > 1.5 (OR 3.200, 95% CI 1.233 to 8.302) were associated with higher risks of bleeding compared with INR ≤ 1.0. DISCUSSION: The risks of thromboembolism and bleeding lie along a continuum, with higher preoperative INR levels conferring higher postoperative bleeding risks after TSA. Clinicians should use a patient-centered, multidisciplinary approach to balance competing risks.

Risk of post-operative bleeding after dentoalveolar surgery in patients taking anticoagulants: a cohort study using the common data model.

This retrospective study aimed to determine risk factors associated with post-operative bleeding after dentoalveolar surgery in patients taking anticoagulants. Patients taking anticoagulants who were planned to undergo periodontal flap operation, tooth extraction or implant surgery were included. Patients were divided into two subgroups according to the maintenance of anticoagulants following medical consultation: (1) maintenance group and (2) discontinuation group. The analysed patient-related factors included systemic diseases, maintenance of anticoagulants and types of anticoagulant. Intra- and post-operative treatment-related factors, haemostatic methods and post-operative bleeding were collected for statistical analyses. There were 35 post-operative bleeding complications (6.5%) in the 537 included patients: 21 (8.6%) in maintenance group and 14 (4.8%) in discontinuation group. The type of anticoagulant (p = 0.037), tooth extraction combined with bone grafting (p = 0.016) and type of implant surgery (p = 0.032) were significantly related to the post-operative bleeding rate. In the maintenance group, atrial fibrillation [odds ratio (OR) = 6.051] and vitamin K inhibitors (OR = 3.679) were associated with a significantly higher bleeding risk. From this result, it can be inferred that the decision to continue anticoagulants should be made carefully based on the types of anticoagulant and the characteristics of dentoalveolar surgeries performed: extraction with bone grafting, multiple implantations and involvement of maxillary arch.

Unveiling the hidden: identification and management of overlooked blood vessels in laparoscopic left hemicolectomy for splenic flexure cancer.

BACKGROUND: During laparoscopic left hemicolectomy procedures, a previously overlooked consistently thick blood vessel within the gastrocolic ligament near the splenic hilum may contribute to post-operative bleeding complications. The purpose of this study was to investigate the identification and management of the previously overlooked blood vessel. METHODS: This is a retrospective descriptive study of patients undergoing laparoscopic left colectomy for splenic fexure cancer conducted at a national gastrointestinal surgery centre in China. Consecutive patients with splenic fexure cancer who underwent laparoscopic left colectomy using our"five-step process"(n = 34) between January 2021 and July 2023 were included. RESULTS: The vessels can be effectively exposed using the aforementioned "five-step process." It was observed that the overlooked vessels consistently present in all patients were identified as the omental branch of the left gastroepiploic artery and vein. CONCLUSION: We have identified the origin of previously overlooked blood vessels and recommended a safe method for their management. This may offer advantages to colorectal surgeons performing laparoscopic left colectomy for splenic flexure cancer.

Risk of post-tonsillectomy hemorrhage among COVID-19 positive pediatric patients.

OBJECTIVE: COVID-19 infection has been demonstrated to increase risk for post-operative bleeding. This study investigated the impact of COVID-19 infection on post-tonsillectomy hemorrhage in pediatric patients, a potentially devastating complication. STUDY DESIGN: Retrospective cohort study. METHODS: The TriNetX database was queried for pediatric patients who underwent tonsillectomy and evaluated for outcomes of primary and secondary post-tonsillectomy hemorrhage. RESULTS: Among subjects 18 years and younger, 1226 were COVID-19 positive and 38,241 were COVID-19 negative in the perioperative period. There was statistically significant increased risk of bleeding with perioperative COVID-19 infection at postoperative days 1, 5, and 10. Additionally, when assessing the role of COVID-19 infection before or after surgery, the risk of bleeding remained statistically significant at all three time points, however these results did not suggest that infection before surgery confers more/less risk compared to infection after. CONCLUSION: The results of this investigation suggest that the presence of COVID-19 in the perioperative period may pose an increased risk for acute or delayed post tonsillectomy hemorrhage. This study employed a large, diverse population and is the first to address this clinical question.

Perioperative Outcomes After Adrenalectomy for Secondary Adrenal Malignancy.

INTRODUCTION: The risk of adverse outcomes after adrenal metastasectomy is not well defined. Knowledge of these risks is essential to guide patient counseling. METHODS: The 2015-2020 National Surgical Quality Improvement Program datasets were combined. Patients who underwent adrenalectomy for secondary adrenal malignancy (SM) and benign nonfunctional (BNF) adrenal neoplasms were identified; BNF neoplasms were chosen as a comparison as functional neoplasms can contribute to comorbidity. Patients who had additional surgery at the time of adrenalectomy were excluded. Patient demographics, comorbidities, perioperative factors, and outcomes were compared between groups. Multivariable logistic regression analysis was performed. RESULTS: Of 3496 adrenalectomy patients, 332 had SM and 3164 had BNF neoplasms. Patients with SM were older (65 versus 54 y) and more often had chronic obstructive pulmonary disease (7.5% versus 4.4%), chronic steroid use (10.5% versus 3.8%), and bleeding disorders (4.5% versus 2.2%) than patients with BNF, respectively (P < 0.01 for all). Laparoscopic adrenalectomy was the most common operative approach for both groups (74.7% versus 88.3%). Rates of mortality, morbidity, reoperation, readmission, and nonhome discharge did not differ significantly between groups. Patients with SM had higher rates of postoperative bleeding than patients with BNF (6.3% versus 2.6%, P < 0.001). This persisted on multivariable regression analysis that adjusted for demographics, comorbidities, and operative approach (odds ratio 2.34, 95% confidence interval 1.19-4.64). CONCLUSIONS: Adrenalectomy for SM is associated with an increased risk of postoperative bleeding compared to adrenalectomy for BNF adrenal neoplasms. Patients with SM that meet criteria for adrenal metastasectomy should be counseled appropriately.

The relationship between posttonsillectomy bleeding to hemogram and coagulation parameters.

PURPOSE: Tonsillectomy is a common surgery performed for indications such as chronic tonsilitis, tonsil hypertrophy and obsructive sleep apnea. Although posttonsillectomy bleeding (PTB) is rare and can be controlled with simple interventions in many patients, it is one of the most feared complications of tonsillectomy surgery. In our study, we investigated the effects of changes in hemogram and coagulation values and seasonal effects on PTB. METHODS: Pediatric and adult patients who underwent tonsillectomy with cold knife method between August 2020 and August 2023 in our clinic were retrospectively reviewed. Demographic data, hemogram and coagulation values of the patients in the control and study groups were recorded and the differences between the two groups in terms of these parameters were evaluated. RESULTS: Our study included 991 patients aged 1-51 years. The rate of PTB was calculated as 2.82%. No patient with primary PTB was found. The duration of bleeding development was 7.03 days. Age, WBC and neutrophil values were statistically significantly higher in the study group. There were no significant differences between two groups in terms of gender, season and other hemogram and coagulation parameters. CONCLUSIONS: Age, high WBC and neutrophil levels were determined as possible risk factors for PTB. Seasonal and gender distribution, aPTT and INR values were similar in the two groups. In order to prevent and predict bleeding, detailed infection investigation should be performed and the risk of bleeding should be considered to increase with increasing age.

BEST-J Score: Validation of a Predicting Model for Delayed Bleeding After Gastric Endoscopic Submucosal Dissection on a European Sample.

BACKGROUND: Delayed bleeding (DB) is a possible adverse event following gastric endoscopic submucosal dissection (ESD). The BEST-J score was created as a risk prediction model for DB following gastric ESD, but is yet to be validated in Western populations. AIMS: We aimed to validate the BEST-J score on a European sample and to perform a subgroup analysis according to histological classification. METHODS: Retrospective study of all consecutive patients undergoing gastric ESD on a European Endoscopic Unit. DB was defined as hemorrhage with clinical symptoms and confirmed by emergency endoscopy from the time of completion to 28 days after ESD. BEST-J score was calculated in each patient and confronted with the outcome (DB). RESULTS: Final sample included 161 patients. From these, 10 (6.2%) presented DB following ESD, with a median time to bleeding of 7 days (IQR 6.8). BEST-J score presented an excellent accuracy predicting DB in our sample, with an AUC = 0.907 (95%CI 0.801-1.000; p < 0.001). Subgroup analysis by histological classification proved that the discriminative power was still excellent for each grade: low-grade dysplasia-AUC = 0.970 (p < 0.001); high-grade dysplasia-AUC = 0.874 (p < 0.001); early gastric cancer-AUC = 0.881 (p < 0.001). The optimal cut-off value to predict DB was a BEST-J score ≥ 3, which matches the cut-off value for high-risk of bleeding in the original investigation. CONCLUSIONS: The BEST-J score still presents excellent accuracy in risk stratification for post-ESD bleeding in European individuals. Thus, this score may help to guide which patients benefit the most from prophylactic therapies following gastric ESD in this setting.

Extended Post Discharge Prophylaxis for Venous Thromboembolism Prevention After Bariatric Surgery.

PURPOSE: The utility of routine post-discharge VTE prophylaxis after bariatric surgery remains a matter of debate. While inpatient chemical prophylaxis decreases the risk of fatal pulmonary embolism, most thromboembolic events occur after discharge and carry high morbidity and mortality. To address this risk, apixaban was introduced as extended prophylaxis for 30 days after surgery. MATERIALS AND METHODS: The study ranges between 1/2014 and 7/2022. Apixaban was incorporated as routine extended prophylaxis protocol in 05/2017 and is dosed at 2.5 mg BID for 30 days. There were two study groups: those who received apixaban on discharge (n = 1443; 60%) and those who did not (n = 953; 40%). Patients with concern for postoperative bleeding (hypotension, unexplained tachycardia with hematocrit drop > 6%, hematocrit drop > 9%), or on preoperative anticoagulant/antiplatelet therapy (except aspirin), were not discharged on apixaban. Post-discharge VTE, readmission, transfusion, and reoperation rates were compared between groups. RESULTS: There were 2396 consecutive primary bariatric operations: sleeve gastrectomy (1949; 81%), Roux-en-Y gastric bypass (419; 18%), and duodenal switch (28; 1%). There were no post-discharge VTEs in patients treated with apixaban vs. five (0.5%) VTEs in patients who did not receive treatment; p = 0.02. There was a higher incidence in post-discharge bleeding events in the apixaban group (0.5 vs 0.3%; p = 0.75), mostly requiring readmission for monitoring without intervention or transfusion. In the apixaban group, one patient underwent EGD for bleeding while another required blood transfusion; there were no reoperations for bleeding. CONCLUSION: There were no post-discharge VTEs in patients who received apixaban. Treatment was associated with a higher risk of self-resolving bleeding events. This study adds to the increasing body of evidence supporting the benefit of routine, extended oral chemoprophylaxis after bariatric surgery.

Risk factors for late postoperative bleeding after partial glossectomy for tongue cancer.

BACKGROUND: Partial glossectomy is the most common procedure for early-stage tongue cancer. Although late postoperative bleeding occasionally occurs, the associated risk factors have not been adequately identified. AIMS/OBJECTIVES: We aimed to investigate the rate and risk factors for late postoperative bleeding after transoral partial glossectomy with or without neck dissection for tongue cancer at our institution. MATERIAL AND METHODS: We analysed 211 patients who had undergone transoral partial glossectomy between January 2016 and January 2023. The potential risk factors associated with late postoperative bleeding were investigated using univariate and multivariate logistic regression analyses. RESULTS: Of the 211 patients, 40 (19%) showed late postoperative bleeding, with 19 (9%) classified as grade IIIa (Clavien-Dindo classification). Regarding all grades, late postoperative bleeding was significantly higher in patients aged <70 years and in those with polyglycolic acid (PGA) sheets (p = .046 and .030, respectively). For grade ≥ IIIa, late postoperative bleeding was significantly higher in patients with a history of anticoagulant/platelet administration, a mucosal defect covered with fibrin glue and a PGA sheet (p = .045 and .026, respectively). CONCLUSIONS AND SIGNIFICANCE: The findings of this study suggest that primary closure decreases the frequency of late postoperative bleeding.

The effect of body mass index on short-term outcomes in patients undergoing off-pump coronary artery bypass grafting surgery: a retrospective study from a single cardiovascular center.

OBJECTIVE: This study is designed to investigate the impact of body mass index (BMI) on the short-term outcomes of patients undergoing off-pump coronary artery bypass graft (OPCAB) surgery. METHODS: Data was obtained from 1006 Chinese patients who underwent isolated, primary OPCAB at a high-traffic cardiovascular center during 2020. Subjects were categorized, by BMI, into a low & normal weight (LN) group (BMI < 24 kg/m2), an overweight (OVW) group (24 ≤ BMI < 28 kg/m2), and an obese (OBS) group (BMI ≥ 28 kg/m2). Information pertaining to patients' short-term outcomes (including incidence of mortality and morbidities; duration of postoperative mechanical ventilation; length of stay in the ICU and hospital; postoperative bleeding; etc.) were extracted, and the data from each group were compared. RESULTS: The incidences of in-hospital mortality and morbidities were similar for all three groups. The volume of fluid infusion, postoperative bleeding within 24 h and total bleeding in LN group were higher than those in the OBS group (P < 0.001). The hemoglobin level was lower in the LN group than that in the OBS group (P < 0.001). Duration of mechanical ventilation and length of stay in the ICU in the LN group were longer than those in the OBS group (P < 0.001). CONCLUSIONS: Our results demonstrate that BMI is not significantly related with short-term outcomes in OPCAB patients. However, we suggest that OPCAB patients with low-normal BMI are more susceptible to post-operative blood loss.