More than one third of adults in the United States are obese (body mass index [BMI, calculated as weight (kg)/[height (m)]2] 30 or greater).1 Women are more likely than men to be obese with a prevalence of 38.3% in 2014.1 Obese women are at increased risk for pregnancy complications including cesarean delivery, preeclampsia, gestational diabetes, macrosomia, and stillbirth, when compared with women with normal BMI.2 Obese women also experience unintended pregnancy at a higher rate than nonobese women.3,4
Despite these increased risks in pregnancy, obese women frequently have poor access to family planning services.5 Multiple studies have identified obesity as a risk factor for delay in receiving abortion care, whether through delay in pregnancy diagnosis or through outpatient clinic policies limiting services for obese women.5,6 Increasing gestational age has long been known to be associated with increased risk for complications in surgical abortions, so delays in care may put this population at greater risk.7
Few studies have investigated obesity as a risk factor for complications in surgical abortion. Previous studies on this topic have included limited patient populations, not controlled for gestational age, or have not evaluated obesity as an independent risk factor.8–10 The majority of abortions in the United States are performed at less than 13 weeks of gestation in outpatient clinics, which often have BMI or weight cutoffs.7,11 As rates of morbid or severe obesity (BMI 40 or greater) continue to increase, abortion access for obese women may continue to be limited.12
We designed this study to investigate whether increasing BMI is an independent risk factor for abortion complications at any gestational age and whether this factor should be used to identify patients who are poor candidates for outpatient procedures. The objective of this study was to evaluate the relationship between obesity and complications of first- and second-trimester surgical abortion in the outpatient setting.
MATERIALS AND METHODS
We conducted a retrospective cohort study of all women presenting for surgical abortions between September 11, 2012, and July 1, 2014, at an outpatient reproductive health clinic network. This clinic network is comprised of three free-standing clinics in Washington state. Patients who have pregnancies earlier than 15 weeks of gestation have a same-day suction dilation and curettage procedure and those at 15 weeks of gestation and above have a 2-day procedure with osmotic dilator placement on the first day and a dilation and evacuation (D&E) procedure on the next day. Procedures above 22 weeks of gestation are typically completed in 3 days with 2 days of osmotic dilators followed by a D&E procedure on the third day. Most patients receive moderate intravenous sedation with a combination of propofol, fentanyl, and midazolam administered by a certified registered nurse anesthetist as well as local anesthesia with a paracervical block, including vasopressin in the second trimester. Procedures are performed by attending physicians, family planning fellows, and residents.
Patients were included in our study if they obtained a surgical abortion during the study time period. Participants were excluded only if BMI data were unavailable. First- and second-trimester procedures were included. We collected data on demographic characteristics, medical comorbidities, and procedure characteristics and complications. All data were abstracted from the electronic medical record and reviewed by two researchers for consistency and errors.
The primary outcome of interest was any complication, including reaspiration, uterine perforation, cervical laceration, infection, emergency department visit, hospitalization, and excessive blood loss defined as estimated blood loss 100 mL or greater. Although there is no universally accepted definition of hemorrhage at the time of surgical abortion, this cutoff was chosen as an amount that would generally be deemed excessive in the setting of a first-trimester abortion.
The primary predictor was BMI, calculated as weight in kilograms divided by height in meters squared. All patients were weighed at the time of their visit, and height was self-reported. This was analyzed as a continuous and categorical variable with BMI categorized by World Health Organization definitions: normal or underweight (BMI less than 25), overweight (BMI 25–29.9), obese class I (BMI 30–34.9), obese class II (BMI 35–39.9), and obese class III (BMI 40 or greater), also referred to as morbid or severe obesity. Multivariable analysis was performed with log-binomial regression to calculate relative risk of complications based on BMI and adjusted for age, gestational age, and history of prior cesarean delivery. All statistical analysis was performed using STATA SE 13.1. This study was approved by the University of Washington institutional review board.
Our three clinic sites performed surgical abortions for 5,157 women between September 2012 and July 2014, and BMI data were available for 4,968 (96.3%) (Fig. 1). The majority (77%) of these abortions was performed in the first trimester. Eight percent of the abortions were performed at 20 weeks of gestation or greater.
The median BMI in our patient population was 25.2 (interquartile range 22.1–30.0). The BMI distribution was as follows: 47.0% were normal weight or underweight, 28.4% were overweight, and 24.6% of patients were obese, including 3.7% with BMI greater than or equal to 40 (class III obesity). The highest BMI in our study population was 67.3. Table 1 provides demographic characteristics of the study population, including a comparison of obese and nonobese women. Women in the study population who were obese were older and more likely to be parous and also included a higher proportion of black women and women using Medicaid to pay for their abortion services. The median procedure length was 6 (interquartile range 4–8) minutes for obese women and 5 (interquartile range 4–8) minutes for nonobese women.
The overall complication rate was 1.7% (Table 2). The most frequent complications were need for uterine reaspiration (1.0%) and estimated blood loss greater than or equal to 100 mL (0.6%). There was no significant difference in complications between the first and second trimesters (1.7% compared with 1.8%, respectively, P=.7). The only specific complications that were associated with gestational age were excessive blood loss, which was higher in the second trimester, and uterine reaspiration, which was higher in the first trimester. Indications for same-day reaspiration included hematometra and incomplete procedure (insufficient pregnancy tissue seen on immediate postprocedure pathologic evaluation). There were no anesthesia-related complications during the study period.
Table 2 also compares complications between obese and nonobese women. There was no difference in overall complication rate, regardless of whether same-day reaspiration was included in the composite complication variable. Excluding same-day reaspiration, the complication rate for obese compared with nonobese women was 1.4% compared with 0.9% (P=.1). There was no clinically significant difference in mean blood loss between procedures for obese women (16.1 mL) compared with nonobese women (13.6 mL), although there was a higher proportion of obese women with blood loss greater than 100 mL (1.1% compared with 0.4%, P=.005). There was no statistically significant increase in estimated blood loss for women with BMI greater than or equal to 40 (class III obesity) compared with normal-weight women (P=.55). We also evaluated BMI as a continuous predictor and found no association between BMI and complications (P=.51). Women who experienced any complication had a median BMI of 24.3 (interquartile range 21.1–29.0); women who did not experience any complication had a mean BMI of 25.2 (interquartile range 22.1–29.9).
We calculated unadjusted and adjusted relative risks of abortion complications (Table 3). Age, gestational age, history of cesarean delivery, and BMI were included in the multivariable model a priori. No additional variables met criteria for inclusion in the model. Body mass index was not associated with increased risk of complications, including when adjusting for age, gestational age, and history of prior cesarean delivery (Table 3).
In a high-volume outpatient abortion clinic with experienced health care providers, obesity does not appear to be an independent predictor for abortion complications. We investigated BMI as both a continuous and categorical variable and were able to control for age, gestational age, and previous cesarean delivery. We saw no increase in overall complications with increasing BMI. These data provide strong evidence against using BMI in isolation to refer women to hospital-based facilities. Although there was a slightly higher risk of estimated blood loss greater than 100 mL among obese women, the overall risk was low at approximately 1%. We do not consider this outcome to be clinically relevant without an increase in complications such as hospital transfer or blood transfusion.
This study demonstrates that obesity is not independently associated with an increased risk for complications in women undergoing outpatient first- and second-trimester surgical abortions. Examining the previously published literature, one recent study found no association between medical comorbidities, including obesity, and first-trimester abortion complications.10 However, obesity was not examined as an independent risk factor. Another study found no association between obesity and second-trimester abortion complications, although statistical power to detect such an association was limited.9 In a larger study of second-trimester surgical abortions, no association was found between obesity and complications of D&E procedures.8 More than 50% of that study population had D&E procedures performed at 20 weeks of gestation or later, and the procedures were performed in a hospital-based facility. This raises the question of the relevance of these data for the majority of women undergoing abortion nationwide, because only 4% of surgical abortions at any gestational age are performed in the hospital setting, and more than 90% of surgical abortions are performed in the first trimester.7,11
Our study found a higher rate of same-day uterine reaspiration in the first trimester. This occurred most frequently at very early gestational ages, because some health care providers at these clinic sites will perform abortion as soon as a gestational sac is visible on transvaginal ultrasonography. This can occasionally result in an additional uterine aspiration within the same encounter after not visualizing adequate tissue on pathologic examination of the products of conception. However, to be conservative, this is classified as a complication in our database.
The overall complication rate was lower than that reported in other studies.8–10 One reason for this may be the low rate of reported hemorrhage. Our clinic protocols include using 4 units of vasopressin in 20 mL lidocaine for paracervical block in the second trimester. Most health care providers also routinely administer 0.2 mg methergine intramuscularly immediately after all second-trimester procedures in addition to 800 micrograms misoprostol placed rectally after all procedures beyond 22 weeks of gestation. These practices could reduce the overall bleeding with procedures. Another explanation is that blood loss is not measured quantitatively; it is an estimated blood loss. Health care providers are likely to underestimate estimated blood loss.13 This should not influence the lack of difference in estimated blood loss or hemorrhage between obese and nonobese women, but likely influences the overall low complication rate of 1.7%. Our estimated blood loss values in particular are low; when blood loss is measured quantitatively, average blood loss is probably greater than 100 mL for D&E procedures.14
Our study is limited by the overall low complication rate, because this makes comparisons between groups more challenging. The low complication rate also makes our statistical analyses less robust. Additionally, we understand that some of our clinic protocols are not the same as all outpatient abortion clinics, which is a potential limitation to the generalizability of these findings.
One strength of the study is the large number of patients included in the study database with complete BMI data. Another strength is that these data include patients from three clinic sites and seven primary attending providers. Many medical students, residents, and fellows also participate in the care of these patients. This diversity of care providers and sites increases the generalizability of these results. Even with so many trainees, and of varying skill levels, the overall complication rate is still very low.
Ultimately, this study supports other work that has been done in this area. Obese women do not have higher rates of complications when controlling for gestational age. Obesity alone should not prevent a woman from accessing abortion in an outpatient setting. Overall, abortion remains a very safe procedure for women at any BMI.
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