The Utility of Postoperative Hemoglobin Testing for Benign Hysterectomy and Myomectomy

Abstract

Objective:

To evaluate the prevalence of a significant decrease in hemoglobin, defined as a drop of ≥2 g/dL, on postoperative day 1 after benign hysterectomy and myomectomy and to compare subsequent interventions on those with and without significant decrease.

Methods:

This is a retrospective cohort study. Operative notes and clinical encounters up to 6 weeks after surgery were reviewed. Patients undergoing laparoscopic, robotic-assisted, abdominal, or vaginal hysterectomy or myomectomy from 1/2014 to 1/2019 at a single tertiary referral center were included. Patients with known malignancy, hysteroscopic or concomitant cesarean surgeries were excluded. Hemoglobin was compared pre- and postoperatively. Postoperative interventions were defined as transfusion, imaging, reoperation, repeat lab draw, and readmission.

Results:

A total of 1120 patients met inclusion criteria and 984 had pre- and postoperative labs drawn. A total of 41% (400/984) had a decrease in hemoglobin ≥2 g/dL. A decrease was least common with the laparoscopic route. Those with a significant hemoglobin drop were older (47.6 vs. 45.4 years, p = 0.0014) and noted to have a lower body mass index (31 vs. 33, p < 0.001), higher preoperative hemoglobin (12.8 vs. 11.5, p < 0.001) and larger estimated blood loss (358 vs. 234 ml, p < 0.001) There was no difference in postoperative transfusion, imaging, reoperation, or readmission between those with and without a significant hemoglobin decrease; however, there was an increase in the number of additional lab draws.

Conclusion:

There is limited utility in measuring hemoglobin routinely after benign gynecological surgery, as there were no additional interventions performed in those with significant decrease other than increased lab draws.

Introduction

A common practice following gynecological surgeries is to draw a routine postoperative hemoglobin to evaluate for postoperative bleeding and assess need for intervention accordingly. An appropriate decrease in hemoglobin reassures the provider that the patient is stable prior to discharge, however, laboratory tests can be costly, extend hospitalization, or lead to potentially unnecessary interventions. The efficacy of perioperative laboratory testing has been examined, and the American Society of Anesthesia recommends against routine preoperative hemoglobin testing.¹

Recent literature in gynecology questions the utility of pre- and postoperative testing,² suggesting that postoperative testing be reserved for those with symptoms or signs of anemia.^3–7 Chamsy et al. concluded that postoperative hemoglobin had little clinical benefit after elective laparoscopic hysterectomy and should be reserved for patients who developed signs and symptoms of acute anemia.⁵ Aldrich investigated vaginal hysterectomy with pelvic organ prolapse surgery and concluded that patients requiring interventions will manifest clinical signs and symptoms of anemia. In that study, those with a lower preoperative hemoglobin or increased change in hemoglobin were at higher risk for transfusion.⁶ Our study sought to investigate the utility of postoperative hemoglobin after all routes of benign hysterectomy and myomectomy.

The primary aim was to evaluate the prevalence of a significant decrease in hemoglobin (Hgb), defined as ≥ 2 g/dL, on routine labs postoperative day 1 (POD1) after benign hysterectomy and myomectomy. Subsequent postoperative interventions were compared in those with and without a significant decrease. Finally, postoperative interventions in those with and without postoperative labs were explored.

Materials and Methods

In this retrospective cohort study, we reviewed all patients who had undergone laparoscopic, robot-assisted laparoscopic, abdominal, or vaginal hysterectomy or myomectomy over a 5-year period between 1/2014 and 1/2019 at a tertiary referral center. Patients with known malignancy, hysteroscopic or concomitant cesarean surgeries were excluded. Institutional review board approval was obtained prior to data collection (HM20016229).

Patients were identified using Current Prodecural Terminology (CPT) codes for open hysterectomy, vaginal hysterectomy, laparoscopic hysterectomy, and fibroid treatment (laparoscopy surgical treatment and abdominal myomectomy) and were screened for inclusion. Operative notes and clinical encounters up to 6 weeks after surgery were reviewed in the electronic medical records. Preoperative hemoglobin values were included if collected anytime within 3 months prior to surgery. Postoperative hemoglobin was collected on the morning after surgery. If patients were not admitted overnight, a postoperative hemoglobin value was not included. Demographic data, medical and surgical history, hemoglobin vales, and indication for surgery were collected. Intraoperative characteristics collected included type of surgery, operating time, estimated blood loss (EBL), uterine weight, pre/intraoperative transfusion, or ketorolac administration. Postoperative interventions were defined as red blood cell transfusion, imaging (CT scan of the abdomen or chest X-ray), reoperation, repeat complete blood count (CBC) draw, and readmission. A composite outcome was defined as the presence of any of the postoperative interventions. A hemoglobin decrease of ≥2 g/dL was defined as “significant” based on data from prior studies.^4–6 One study reported a mean hemoglobin decrease of 2.6 g/dL in patients with symptoms of anemia vs. 2.1 g/dL in asymptomatic patients, respectively.⁶ Another reported a decrease of 2.66 g/dL in symptomatic patients vs. 1.8 g/dL in asymptomatic patients, respectively.⁵

Descriptive statistics compared outcomes between those with and without hemoglobin decrease ≥2 g/dL on POD1. For continuous variables, the mean and standard deviation is reported; for categorical variables, the rate and percentage are reported. A two-tailed t-test was used to compare continuous variables and a chi-square test for categorical variables. Statistical significance was defined as p < 0.05. A logistic regression was performed to evaluate risk factors for decrease in hemoglobin or transfusion and adjust for baseline differences between groups. Risk factors included age, smoking, body mass index (BMI), preoperative transfusion, EBL, uterine weight, route of surgery, indication for surgery, operating time, ketorolac administration. (JMP^®, Version 15. SAS Institute Inc., Cary, NC, 1989–2021).

The sample size was chosen based on the number of cases done at our institution and the number included in prior studies.^4–7 For our post-hoc power calculation comparing our study group to the population where the prevalence of significant Hgb drop ≥2 g/dL is 2.5–25%, with a group size of 984, prevalence of 41%, and alpha 0.05, we have >95% power to detect a significant Hgb drop.

Results

A total of 1120 patients met inclusion criteria. 984 (88%) had pre- and postoperative labs available, of which 400 patients (41%) had a significant hemoglobin decrease. (Fig. 1)

FIG. 1.

Flowchart of patients included in the study.

Those with and without a significant hemoglobin decrease were compared. Tables 1 and 2 report demographic and perioperative characteristics. Those with a significant hemoglobin decrease were noted to be older (47.6 vs. 45.4 years, p = 0.0014), with a lower BMI (30.9 vs. 32.9, p < 0.001), and higher preoperative hemoglobin (12.8 vs. 11.5, p < 0.001). Medical conditions, other than cardiac disease, and surgical history were similar between groups. (Table 1) Intraoperative characteristics including operative time, pre- and intraoperative transfusion, ketorolac administration, and uterine weight were similar between groups. EBL was larger in those with a significant hemoglobin decrease (358 mL vs. 234 mL, p < 0.001). (Table 2) Indications for surgery are shown in Supplementary Table S1. The majority of patients with abnormal uterine bleeding did not have a significant drop in hemoglobin.

Table 1.

Demographic Information and Surgical History for Those with and Without Significant Hemoglobin Decrease

Characteristic	Hgb decrease ≥2 (n = 400)	Hgb decrease <2 (n = 584)	p-value
Medical history
Age (years)	47.6 (46.5–48.7)	45.4 (44.6–46.2)	0.0014
BMI	30.9 (30.2–31.6)	32.9 (32.3–33.6)	<0.001
Preoperative hemoglobin (g/dL)	12.8 (12.7–13.0)	11.5 (11.3–11.6)	<0.001
Congestive heart failure	6 (1.5%)	7 (1.2%)	0.68
Other Cardiac disease	18 (4.5%)	11 (1.9%)	0.017
Chronic kidney disease	1 (0.25%)	7 (1.2%)	0.1
Diabetes mellitus	41 (10.3%)	57 (9.8%)	0.8
Hepatitis	7 (1.8%)	16 (2.7%)	0.3
Hypertension	138 (34.5%)	235 (40%)	0.07
History of malignancy	19 (4.75%)	27 (4.6%)	0.93
Tobacco use	96 (24%)	146 (25%)	0.7
Surgical history
History of laparoscopy	40 (10%)	43 (7%)	0.14
History of laparotomy	103 (25.8%)	180 (30.5%)	0.08
History of cesarean section	86 (21.5%)	138 (24%)	0.4

Italics represents P value <0.5.

Table 2.

Perioperative Characteristics Between Those with and Without a Significant Hemoglobin Decrease

Characteristic	Hgb decrease ≥2 (n = 400)	Hgb decrease <2 (n = 584)	p-value
Operating Time (minutes) (385/575)	180.4 (173.7–187.2)	176.3 (170.7–181.8)	0.35
EBL (mL)	358 (320–397)	234 (212–255)	<0.001
Uterine weight (g) (374/551)	485.4 (390.2–580.5)	448.9 (395.4–502.4)	0.5
Preoperative transfusion	4 (1%)	16 (2.8%)	0.059
Intraoperative transfusion	13 (3%)	30 (5%)	0.15
Ketorolac administration	250 (62.5%)	356 (61.4%)	0.7

Italics represents P value <0.5.

When comparing surgical approaches (Table 3), there was a trend where laparoscopic hysterectomy was less likely to have a significant hemoglobin decrease, and abdominal myomectomy was more likely to have a significant hemoglobin decrease, however, this was not statistically significant.

Table 3.

Prevalence of Hemoglobin Decrease Based on Surgical Approach

Type of surgery	Hgb decrease ≥2	Hgb decrease <2	p-value
Abdominal hysterectomy	128/313 (41%)	185/313 (59%)	0.9
Vaginal hysterectomy	107/237 (45%)	130/237 (55%)	0.1
Laparoscopic hysterectomy	99/285 (35%)	186/285 (65%)	0.02
Robotic-assisted laparoscopic hysterectomy	30/75 (40%)	45/75 (60%)	0.5
Abdominal myomectomy	35/68 (51%)	33/68 (48%)	0.06
Robotic-assisted laparoscopic myomectomy	1/6 (17%)	5/6 (83%)	0.2

Italics represents P value <0.5.

A multivariable logistic regression model was fit to control for baseline differences between groups and to assess factors associated with a larger hemoglobin decrease. Hgb decrease ≥2 g/dL was independently associated with lower BMI, older age, and higher EBL, but was not independently associated with transfusion, preoperative transfusion, smoking, uterine weight, operating time, ketorolac administration, or route of surgery.

The secondary aim was to compare postoperative interventions in those with and without a significant hemoglobin decrease. When looking at composite outcome of any postoperative intervention, there was a statistically significant difference between groups driven by the difference in repeat lab draws. Otherwise, there were no statistically significant differences between the two groups with regards to individual interventions including transfusion, imaging, or readmission (Table 4). Reoperation was higher in the significant hemoglobin decrease group, however with a very low number overall (n = 3). Those with a significant hemoglobin decrease more frequently had an additional CBC drawn (19% (76/400) vs. 13% (78/584) of patients, p = 0.017).

Table 4.

Postoperative Interventions in Those with and Without a Significant Hemoglobin Decrease

Intervention	Hgb decrease ≥2 (n = 400)	Hgb decrease <2 (n = 584)	p-value
Transfusion	28 (7%)	25 (4%)	0.06
Imaging	10 (2.5%)	15 (2.6%)	0.94
Reoperation	3 (0.75%)	0 (0%)	0.04
Additional CBC Drawn	76 (19%)	78 (13%)	0.017
Readmission	11 (2.8%)	31 (5.3%)	0.051
Composite	77 (19%)	78 (13%)	0.013

Italics represents P value <0.5.

These postoperative interventions were further evaluated by route of surgery and showed similar trends. After abdominal myomectomy, transfusion was higher in those with a significant hemoglobin decrease (17% vs. 3%, p = 0.044). For all other approaches, transfusion was not significantly different between groups. Additional CBC draws were more frequent in those with a significant hemoglobin decrease for all surgical routes.

To assess factors associated with transfusion, a logistic regression was fit. Higher EBL and preoperative transfusion were independent risk factors; BMI, age, smoking, operating time, uterine weight, route of surgery, ketorolac administration, and Hgb decrease ≥2 g/dL were not associated.

Finally, although a low sample size, we explored the difference in those with (n = 1017) and without (n = 103) POD1 labs. Demographic information and perioperative characteristics are shown in Supplementary Tables S2 and S3. Those with no postoperative labs had significantly higher preoperative hemoglobin (12.0 vs. 12.7, p = 0.0002), however, this difference is likely clinically insignificant. Those with postoperative labs had a significantly higher EBL (284 mL vs.125 mL, p < 0.001) and uterine weight (455 vs. 214 g, p < 0.001) compared with those without postoperative labs. Postoperative interventions are shown in Table 5. Transfusion, imaging, reoperation, and readmission were not statistically significantly different.

Table 5.

Postoperative Interventions in Those with and Without POD1 Hemoglobin Drawn

	POD1 hgb (n = 1017)	No POD1 hgb (n = 103)	p-value
Transfusion	53 (5%)	1 (0.97%)	0.055
Imaging	25 (2.5%)	0 (0%)	0.1
Reoperation	3 (0.29%)	0 (0%)	0.58
Readmission	43 (4%)	2 (2%)	0.27

Discussion

Over 5 years at this tertiary care center, the majority of patients undergoing benign hysterectomy or myomectomy had a hemoglobin measured on POD1 (1017/1120, 91%). Only 41% of the patients who had labs drawn pre- and postoperatively had a significant decrease in Hgb, and this did not lead to a change in interventions other than additional lab draws.

The findings support prior literature, which suggests that postoperative labs should be based on objective clinical evidence rather than a routine order.^3–7 Aldrich et al.⁶ noted that patients with signs or symptoms of anemia had a hemoglobin decrease of 2.6 g/dL compared with 2.1 g/dL in those without signs and symptoms. Chamsy et al.⁵ reported symptomatic patients had a hemoglobin decrease of 2.66 g/dL versus 1.8 g/dL in those without symptoms. Our study shows that even in those with a hemoglobin decrease ≥2 g/dL, there was not a significant difference in interventions other than additional labs drawn.

This study expands on prior literature to include all surgical approaches to hysterectomy and myomectomy. For abdominal myomectomy, postoperative blood transfusion was more common in those with a significant hemoglobin decrease, but for all other routes of surgery, postoperative transfusion rate was similar in those with and without a significant hemoglobin decrease. Prior literature reports a transfusion rate of 0.5%—1.7% after minimally invasive hysterectomy and 5.7% after abdominal hysterectomy,⁸ which is lower than our data.

The average cost of a CBC has been cited at $2–2.8 million per year.^5,6 Eliminating the use of postoperative labs on all patients would help to reduce this laboratory cost. With the current trend in same day discharge for minimally invasive hysterectomy,^9–12 the results of this study provide reassurance that most patients do not have to stay for a POD1 lab draw.

The design of this study relies on the accuracy of historical medical records. Available postoperative lab values were collected which often were not distinguished between those ordered routinely and those ordered due to clinical symptoms. The timeframe chosen also included cases done before the implantation of an enhanced recovery after surgery protocol. Data on preoperative optimization such as iron infusions and GnRH agonists and intraoperative techniques to control bleeding was not collected.

This study was performed at a single, tertiary care center with training physicians; however, the large sample size adds strength to the conclusions. The study was powered for the primary outcome but not for individual interventions or those without labs drawn. Surgeries were performed by all subspecialties of gynecology including OBGYN specialists and those fellowship trained in minimally invasive gynecology, female pelvic reconstructive surgery and pelvic medicine, and gynecological oncology.

Conclusion

Overall, postoperative hemoglobin resulted in increased laboratory draws without an increase in other major interventions. Therefore, there is limited utility in measuring hemoglobin routinely after benign hysterectomy and myomectomy.

Footnotes

Authors’ Contributions

K.V.S. conceptualization, methodology, investigation, formal analysis, and writing; M.D.T. conceptualization and supervision; C.W. investigation; L.N.S. methodology, formal analysis, writing, and supervision.

Author Disclosure Statement

The authors report no conflicts of interest.

Funding Information

No funding was received for this article.

Supplementary Material

References

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Supplementary Material

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