The Effect of Obesity on Total Abdominal Hysterectomy

Abstract

Objective:

To compare perioperative outcomes of total abdominal hysterectomy (TAH) between obese and nonobese women.

Methods:

The medical charts of all women who underwent TAH for benign gynecological conditions at Temple University Hospital between 1997 and 2002 were reviewed. We excluded those who had concomitant surgery except for adnexal removal. The rates of perioperative indices were compared between obese (body mass index [BMI]≥30 kg/m²) and nonobese women; p < 0.05 was considered significant.

Results:

Of 357 women, 172 (48.2%) were obese, and 185 (51.8%) were not. Among the baseline characteristics, only race was statistically different between the groups. There were more African American women among the obese women (82.5% vs. 70%, p < 0.05). Postoperative complications, including urinary tract injury, were not significantly increased in the obese group. On the contrary, nonobese women had a significantly higher incidence of ileus (13.5% vs. 6.4%, p < 0.05). Although operative time was significantly prolonged for obese women, obesity did not increase the length of hospitalization, transfusion rate, and perioperative hemoglobin change. All these results remained the same even after controlling for race.

Conclusions:

Contrary to the general opinion, obesity does not significantly affect the perioperative outcomes for TAH performed for benign gynecological causes.

Introduction

Obesity presents a major health problem in the United States. According to the 2003–2004 National Health and Nutrition Examination Survey (NHANES), approximately two thirds of American adults are overweight or obese.¹ Consequences of obesity epidemics are encountered commonly in many medical fields. The effect of body mass index (BMI), the most objective measure of body weight, on surgical complications has varied in different surgical areas.^2

–5 Although obesity is often regarded by most gynecologists as a surgical risk during laparotomy, its association with perioperative morbidity has not been well studied for abdominal hysterectomies in the United States. This is quite surprising when approximately two thirds of >600,000 hysterectomies are performed via laparotomy every year.⁶ The purpose of this study was to compare the perioperative outcomes of abdominal hysterectomy between obese and nonobese women.

Materials and Methods

We conducted a retrospective review of the medical records of all women who underwent total abdominal hysterectomy (TAH) for benign gynecological conditions at Temple University Hospital from January 1997 to December 2002. Patients who underwent any other concomitant procedure except for adnexal removal and cystoscopy were excluded from the study. The study population was divided into two groups according to the BMI as obese (BMI≥30 kg/m²) and nonobese (BMI<30 kg/m²).

We chose the urinary tract injury rate as our primary outcome. In our institution, the rate of urinary tract injury averaged around 3% over the last few years. Assuming that a clinically significant predisposing factor should double the rate of this outcome measure, we needed 62 patients in each group in order to have an 80% power with an α value of 0.05. The database provided patient characteristics, such as age, sex, race, gravity, and parity. We also collected information about coexisting medical conditions, indications for hysterectomy, and previous abdominal/pelvic surgeries. Perioperative complications, such as postoperative febrile morbidity, ileus, bowel and urinary tract injury, wound complications, urinary tract infections (UTI), urinary retention, tromboembolic events, and postoperative hemorrhage requiring blood transfusion, were compared. In addition, perioperative hemoglobin change, operative time, and length of hospital stay were studied.

All patients received preoperative antibiotic prophylaxis, general anesthesia, and overnight indwelling urinary catheterization. We combined any injury to ureters or bladder as urinary tract injury. For febrile morbidity, the criterion was any temperature of ≥100.4°F on two separate occasions at least 6 hours apart excluding the first 24 hours after surgery. Nausea and vomiting with delayed oral intake, abdominal distention, and decreased bowel sounds that resolved with conservative management were considered as ileus. UTI was diagnosed by growth of at least 100,000 colony-forming units (cfu)/mL of a urinary tract pathogen in a culture of a midstream urine sample. Wound complication was diagnosed when there was drainage or erythema or necrotic appearance that required exploration of the incision with early removal of staples or stitches. The patients were considered to have postoperative hemorrhage when the records indicated they had clinical signs of bleeding with rapidly dropping hemoglobin levels that led to transfusion or reoperation.

The study protocol was approved by the institutional review board. Frequency tables and Fisher's exact test and independent t tests were used for categorical and continuous variables, respectively. Significance was assigned at p < 0.05. The relationship of the perioperative outcome measures with obesity was estimated with univariate logistic regression analysis, which generated the odds ratio (OR) and the 95% confidence interval (CI) for each discrete variable. Finally, multivariable stepwise logistic regression was used to ascertain if each variable was independently significant. SAS (Cary, NC) software was used for all statistical analysis.

Results

There were 357 TAH performed for benign gynecological conditions during the study period. The obese and nonobese groups included 172 (48.2%) and 185 (51.8%) patients, respectively. The mean BMI for the obese group, which was 36.8 ± 5.2 kg/m², was significantly different from 25.1 ± 3.1 kg/m² in the nonobese group (p < 0.0001). As seen in Table 1, the patient characteristics were similar between the groups except for racial distribution. The obese group included significantly more African American women (82.6 vs. 70.3%, p = 0.006). In both groups, the most common indication was uterine leiyomyomas, followed by abnormal uterine bleeding (Table 2). Pelvic mass was an indication more often in obese women (14.5%) than in nonobese women (5.4%) (p = 0.004), whereas cervical intraepithelial neoplasia (CIN) was more common in nonobese women (7.0%) than in obese women (1.1%) (p = 0.007). Table 3 demonstrates that hypertension was the only variable that was significantly different among the comorbid conditions and previous abdominal/pelvic surgery. As expected, more women in the obese group had this medical condition (45.9 vs. 25.9%, p = 0.009).

Table 1.

Patient Characteristics

Characteristic	Obese BMI≥30 kg/m ² (n = 172)	Nonobese BMI<30 kg/m ² (n = 185)	p value
Mean BMI ± SD	36.8 ± 5.2	25.1 ± 3.1	<0.0001
Mean gravity ± SD	3.3 ± 2.0	2.9 ± 1.9	NS
Mean parity ± SD	2.4 ± 1.5	2.3 ± 1.6	NS
Mean uterine weight (g) ± SD	662.4 ± 810.4	555.6 ± 664.5	NS
Mean age (years) ± SD	45.0 ± 7.8	44.9 ± 8.0	NS
African American	142 (82.6%)	130 (70.3%)	0.006

BMI, body mass index; NS, not significant; SD, standard deviation.

Table 2.

Indications for Hysterectomy

Indication	Obese BMI≥30 kg/m ² (n = 172) n (%)	Nonobese BMI<30 kg/m ² ) (n = 185) n (%)	p value
Leiomyoma	123 (71.5)	127 (68.6)	NS
Abnormal uterine bleeding	49 (28.5)	47 (25.4)	NS
Chronic pelvic pain	17 (9.9)	26 (14.1)	NS
Uterine prolapse	3 (1.7)	9 (0.5)	NS
Pelvic mass	25 (14.5)	10 (5.4)	0.004
Cervical dysplasia	2 (1.1)	13 (7.0)	0.007
Endometrial hyperplasia	5 (2.9)	6 (3.2)	NS

Table 3.

Comorbid Conditions and Previous Abdominal/Pelvic Surgery

Comorbid condition or surgery	Obese BMI≥30 kg/m ² (n = 172) n (%)	Nonobese BMI<30 kg/m ² (n = 185) n (%)	p value
Hypertension	79 (45.9)	48 (25.9)	0.0092
Diabetes mellitus	18 (10.5)	16 (8.6)	NS
Chronic obstructive pulmonary disease	6 (3.5)	5 (2.7)	NS
Uterine surgery^a	55 (32.0)	43 (23.2)	NS
Adnexal surgery^b	19 (11.0)	15 (8.1)	NS
Bowel surgery^c	6 (3.5)	6 (3.2)	NS

Cesarean delivery and myomectomy.

Oophorectomy, ovarian cystectomy, salpingectomy, salpingostomy.

Appendectomy, laparotomy with bowel resection and reanastomosis.

Table 4 shows the incidence of perioperative complications and outcome measures. Urinary and bowel injury were each within the 1%–3% range and similar between the groups. Surprisingly, ileus was more common in nonobese women (13.5% and 6.4% for nonobese and obese women, respectively p = 0.012). Although wound complications seem to be increased in obese women (4.1%) when compared with nonobese women (1.1%), this difference did not reach statistical significance. Mean operating time in obese women (123.8 ± 54.5 vs. 101.8 ± 40.4 minutes in nonobese women, p = 0.0001) was significantly longer, but the length of hospital stay was approximately 3 days, without significant difference between the groups. Adjustment with logistic regression did not change differences in the mean operating time and ileus. Looking at the modest falls in the perioperative period within the range of 1–2 g/dL in both groups, transfusion, with similar rates between the obese (14%) and nonobese (13%) women, was likely necessary because of preoperative anemia in this patient population.

Table 4.

Perioperative Complications and Outcome Measures

	Obese BMI≥30 kg/m ² (n = 172) n (%)	Nonobese BMI<30 kg/m ² (n = 185)	p value
Febrile morbidity^a	55 (32.0)	58 (31.4)	NS
Urinary tract injury	5 (2.9)	4 (2.2)	NS
Bowel injury	3 (1.7)	3 (1.6)	NS
Wound complication	7 (4.1)	2 (1.1)	NS
Ileus	11 (6.4)	25 (13.5)	0.012 (adjusted)
Thromboembolism	2 (1.1)	0 (0)	NS
Urinary tract infection	13 (7.6)	12 (6.5)	NS
Urinary retention	3 (1.7)	0 (0)	NS
Postoperative bleeding	0 (0)	0 (0)	NS
Mean operating time (minutes) ± SD	123.8 ± 54.5	101.8 ± 40.4	<0.0001 (adjusted)
Mean length of hospital stay (days) ± SD	3.45 ± 1.8	3.32 ± 1.5	NS
Mean change in hemoglobin (g/dL) ± SD	1.75 ± 1.4	1.85 ± 1.4	NS
Transfusion	24 (14.0)	24 (13.0)	NS

Oral temperature ≥100.4°F.

There were only 46 morbidly obese women with BMI of ≥40 kg/m² in our sample. When these women were analyzed against obese women whose BMI was at least 30 kg/m² but lower than 40 kg/m² and nonobese women using chi-square test, our results did not change significantly. Of note, because of the nature of the chi-square test, this comparison was not possible when there were <5 occurrences for each variable. The mean BMI of the morbidly obese group was significantly higher (43.7 ± 3.6, 34.3 ± 2.8 for the obese women, and 25.1 ± 3.1 kg/m² for the nonobese women). Their other baseline characteristics were similar to those of the other groups with the exception of the prevalence of pelvic mass as an indication. Among the outcome measures, only febrile morbidity, length of operating time, length of hospital stay, perioperative hemoglobin change, and transfusion rate had adequate occurrences for meaningful analysis. The only significant difference was observed for the operating time with the adjusted linear model (139.5 ± 53.5, 118.0 ± 53.9, and 102.1 ± 40.5 minutes in morbidly obese, obese, and nonobese women, respectively (p < 0.0001).

Discussion

The obesity epidemic is posing a serious challenge to the healthcare system. Given the growing rates worldwide, its effect on surgical outcomes is becoming increasingly relevant. The previous studies evaluating the effect of obesity in abdominal surgery used a variety of definitions of obesity, including percent of ideal body and absolute weight. Cruse and Foord,³ in their retrospective review of 23,000 surgical wounds, noted a 13% incidence of wound infection in obese patients treated with abdominal surgery compared with <5% in women with normal weight. Mullen et al.⁴ compared the impact of BMI on perioperative outcomes in patients undergoing major intraabdominal cancer surgery. They found that obesity was not a risk factor for postoperative mortality or major complications but was a risk factor for wound complications. In a study focusing on obesity in general elective surgery, Dindo et al.⁵ showed that obese patients did not face a higher risk for postoperative complications. They reported similar operating time and transfusion rates for obese and nonobese patients.

Despite the high abdominal hysterectomy rates and the threat of the obesity epidemic, the effect of obesity on short-term surgical outcomes of TAH has not been studied adequately. To our surprise, we found more reports on the effect of obesity in less commonly performed procedures, such as total laparoscopic hysterectomy and hysterectomy for gynecological cancers, than those focusing on TAH with benign indications. Only a few studies used the BMI criteria when studying hysterectomy outcomes with relation to the body weight. Rasmussen et al.⁷ from Denmark were not able to find any significant difference in perioperative morbidity among different BMI categories except for prolonged operative time for obese women. In contrast, wound hematoma was seen more often in nonobese women in their study. The only American study devoted to study the impact of obesity on TAH was published more than 30 years ago.⁸ Unfortunately, it did not use BMI to categorize the patients. In that report of more than 200 women weighing ≥200 lbs, Pitkin concluded that obesity increased morbidity associated with TAH. He found increased operative time and blood loss as well as an extremely high rate of wound complications (29%), which was 7-fold increased compared with that in normal weight patients. We noticed the need for a study that reflects today's surgical outcomes using the modern definition of obesity based on BMI. In our study, obesity did not influence the rates of urinary tract injury, febrile morbidity, bowel injury, wound complications, UTI, urinary retention, thromboembolism, bleeding, and the length of hospital stay. Our results showed a lower operating time but higher rate of ileus in nonobese women compared to their obese counterparts.

There is more evidence for hysterectomies with oncological indications. In endometrial cancer, abdominal hysterectomy in obese women led to 5-fold and 10-fold increased risks for wound infection and separation, respectively.⁹ Obesity increased the operating time and blood loss in women who underwent radical hysterectomy for cervical cancer.¹⁰ In our previous study, we evaluated perioperative outcome measures of abdominal and vaginal hysterectomies in obese women. This study showed a lower incidence in fever, ileus, UTI, and wound complications after vaginal hysterectomy compared with abdominal hysterectomy in obese women. The vaginal approach in obese women resulted in shorter operative time and required shorter hospital stay compared with the abdominal procedure.¹¹

Obesity is commonly presumed to pose increased morbidity for abdominal hysterectomy despite lack of strong contemporary data. Our results indicate that obesity does not have a significant effect on the short-term outcomes of TAH. We believe that this report provides important evidence for practicing gynecological surgeons. The results of this study should be viewed with caution, however, because of its retrospective design with potential biases. This study was underpowered to show a significant difference in the wound infection rate. Delayed complications were possibly missed, as we did not have access to outpatient records. Therefore, prospective multicenter studies with large sample size and longer follow-up with the same objective are in order.

Footnotes

Acknowledgments

This work was presented as a poster at the American College of Obstetricians and Gynecologists 54th Annual Clinical Meeting, May 6–10, 2006, Washington, DC.

Disclosure Statement

None of the authors have any commercial association that might pose any financial, personal, or academic conflict of interest, either directly or through immediate family, in such areas as expert testimony, consulting, honoraria, stock holdings, equity interest, ownership, patent-licensing situations, or employment.

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