Incidence

Cesarean delivery (CD) is the most common surgery for hospitalized women in the United States. From 1970 to 2014, the rate of primary CD in the United States increased from 5.5% to 32.2%.^1,2 The concurrent rise in rates of overweight and obese women, now representing over two-thirds of the population, is one of myriad factors playing a role in this trend.³ Several studies have reported an association between higher body mass indexes (BMIs) and higher rates of CD.^4,5,6,7,8 In a meta-analysis from 2009, likelihood ratios of undergoing CD were 1.46 (95% confidence interval [CI] 1.34–1.60), 2.05 (95% CI 1.86–2.27), and 2.89 (95% CI 2.28–3.79) in populations of overweight, obese, and severely obese women (BMI > 35–40 depending on the study), respectively, compared with normal-weight pregnant women.⁸ One statewide analysis in the United States determined that 1 in 7 CDs was attributable only to being overweight or obese.⁹

Contributing Factors

While higher rates of preexisting and pregnancy-related diabetes and hypertension are seen in the pregnancies of overweight and obese women, the additional risk for CD appears to be independent of the common comorbidities.⁴ Many factors may play a role in the obese woman’s increased risk for a CD, including, but not limited to, excess weight gain in pregnancy, slower progress in the first stage of labor, differences in myometrial contractility, fetal macrosomia, placental inflammation, inadequate intrapartum fetal monitoring, and soft tissue dystocia.^4,10,11 Iatrogenic causes, such as higher induction rates and provider bias toward CD, may also fuel this trend. The relationship between obesity and CD not only contributes to a rise in health care spending¹² but also affects women’s complications in childbirth, postpartum course, future pregnancy care, and her long-term health and potentially that of her offspring.

Surgical Risk

Surgery on obese patients is associated in general with an increase in operative time, cost, and complications, in particular disturbed wound healing.¹³ CD in obese women is associated with a higher number of complications, such as blood loss, postoperative infection, readmission, and venous thromboembolism (VTE).^11,14,15,16 Importantly for obesity research, the American College of Obstetricians and Gynecologists (ACOG) recognizes severe hypertension, VTE, and obstetric hemorrhage as the three top national priorities for prevention of maternal mortality and morbidity,¹⁷ all more commonly diagnosed in the setting of elevated BMI.

With the global focus on patient safety and utilization of quality benchmarks like readmission and surgical site infection, hospitals are increasingly looking to improve intrapartum and postpartum care for this at-risk population. Recognizing the challenges for the growing population of women with class III or “supermorbid” obesity at delivery, often defined as BMI greater than 50, regional high-risk centers increasingly accept these patients for antepartum referral.

Prenatal Counseling

All overweight and obese women should be counseled about their increased risk for CD. Reproductive health counseling in the preconception period should emphasize the benefits of weight loss for reducing prepregnancy BMI; even a minimal amount of weight loss can result in improvement in pregnancy outcomes.¹⁸ As the incidence of attempted vaginal birth after cesarean in the United States remains low at 1 in 5 women,¹⁹ there may be greater obstacles for obese women compared to women of normal BMI; avoiding the first CD is always the best strategy when possible and safe.

Risk Reduction

Antepartum risk reduction strategies include counseling about appropriate weight gain, encouraging healthy physical activity and nutritional choices, and optimizing glycemic control if diabetes mellitus is preexisting or diagnosed during pregnancy. As many as 40% of obese women gain more weight than is recommended by the Institute of Medicine guidelines (11–20 lb for women with a BMI > 30).²⁰ Research on the prevention of excess gestational weight gain has not been promising. One Australian trial of over 2000 overweight and obese pregnant participants that randomized them to continuous advice and behavioral support on issues of nutrition and exercise was unique in looking at outcomes rather than simply at gestational weight gain. It found no significant differences in rates of infants who were large for gestational age or in those of multiple maternal outcomes, including CD (34% control group vs. 37% intervention group, p = .33).²¹ There is a need for more research into understanding the etiologies of excessive gestational weight gain, why obese women are more at risk, and, more important, evidence-based strategies for prevention, such as intensified lifestyle interventions or pharmaceutical means, such as are being examined in forthcoming trials of metformin in the nondiabetic obese.²²

Screening

Obese women of reproductive age have higher rates of chronic hypertension, diabetes, asthma, and sleep apnea, not all of which are recognized prior to pregnancy. A screening electrocardiogram or echocardiogram should be considered in patients with a cardiac history, chronic hypertension, pregestational diabetes, or sleep apnea. A routine anesthesia consultation may not be indicated for most obese women, but additional medical comorbidities or a history of anesthesia complications should prompt consideration of this service.

Preoperative Counseling

Women undergoing CDs should be counseled about the increased risks for hemorrhage, infectious morbidity, and VTE. There is not a BMI at which it is universally accepted to perform an elective CD for maternal weight alone, especially in the setting of potential future childbearing and the risks of repeat surgery. However, several series have highlighted the challenges in the smaller population of women with BMIs above 50.^5,6 Obese women are more likely to be induced and require interventions such as internal monitoring.⁷ In addition, they have more barriers to emergency CD, including possible delays in securing intravenous access, difficulty with transport, achieving adequate anesthesia, and longer time to delivery.¹⁴

While a routine consult is not obtained for all obese surgical candidates, the on-staff anesthesiologists should be made aware of any patient admitted with class III obesity. Labor epidurals can be useful for obese women due to the option of employing it later if a CD becomes necessary.²³ There is a lack of evidence suggesting that a labor epidural is a contributing factor in CD in the overweight or obese population, but that topic may warrant further investigation, particularly for nulligravidas. As with patients of normal BMI, spinal anesthesia is preferred for patients undergoing CD, but it is not without technical challenges. Patients should be advised about the higher rate of failed placements of regional anesthesia in some obese women due to soft tissue differences.

For women requiring general anesthesia, airway edema and increased soft tissue may be obstacles to visualization, such that as many as 1 in 3 obese women may have a difficult intubation.²³ Obtaining adequate anesthesia in this population can be particularly challenging in the setting of obstetric emergencies such as cord prolapse or acute high-volume hemorrhage with previa or abruption.

Operating Tables

A CD that is safe for both the obese patient and the operating room team can require the presence of specialized equipment. Surgical staff should be aware of weight limitations of all pieces of equipment, especially operating tables, most of which tolerate 350–500 lb.²⁴ Special bariatric tables can accommodate up to 600–1000 lb. Additional side extensions allow for patients with wider body habitus and are cushioned to prevent compression injury of soft tissue during surgery. Awareness of the extra risk of special positioning during CD such as leftward tilt or, less commonly, Trendelenburg, is important for preventing falls.

Instruments

Surgical instruments, particularly retractors, come in larger and longer sizes for surgery in the bariatric population. A disposable, self-retaining retractor can be helpful in evenly compressing the subcutaneous adipose tissue, especially in the absence of intra-abdominal adhesive disease or with limited assistants to manually retract soft tissue. Although instruments required during CD are less likely to require modifications for obese patients, in the setting of conversion to hysterectomy or working deeper in the pelvis (i.e., repairing a uterine extension), longer instruments may prove useful.

Transfer Devices

An air-assisted mattress is an inflatable device designed for lateral transport of the obese patient from bed or stretcher to operating table and back. It must be placed below the patient prior to anesthesia and is inflated during transfer. As it is a sliding transfer, it avoids the need to roll the patient to the extreme lateral position needed to place sliding boards, it reduces the need for load-bearing lifting on the part of the staff, thus reducing the risk for patient falls and staff injuries, and can bear up to 1200 lb.

Antibiotic Prophylaxis

Preoperative antibiotics prior to CD are recommended as it is considered “clean contaminated.” Women are at increased risk for surgical site infections compared to other procedures, and CD is the biggest risk factor for postpartum endometritis.²⁵ For women undergoing CD and not already receiving antibiotics for chorioamnionitis or premature rupture of membranes, an antibiotic such as a first-generation cephalosporin should be administered within 60 minutes of the procedure.²⁵ Antibiotic dosing is based currently on maternal weight due to preliminary evidence that obesity alters pharmacokinetics; for example, in women with BMI over 30 would receive 2 g of cefazolin instead of the standard 1 g.²⁵ While evidence exists that women with even higher BMIs may not achieve recommended tissue levels under current guidelines,²⁶ the clinical impact on infection rates has not been studied. More research is needed to define the best prophylactic dosing for women with class III obesity.

Incision Site

Positioning and prepping the patient in the operating room requires deciding first where to make the skin incision. For the majority of overweight and obese women, a low transverse incision of the Joel-Cohen or Pfannenstiel type is appropriate. However, incision sites described for the obese patient with a large panniculus can be divided into three types: subpannus, suprapannus transverse, and suprapannus vertical.

Advocates of placing the incision above the panniculus have been based on hypotheses that doing so avoids a humid, yeast-prone area potentially more conducive to surgical site infection, obviates the need to retract the panniculus above the operative field during surgery, and offers greater ease for inspecting the healing incision for the patient, her family, and health care professionals (Figure 21-1).

Proponents of the subpannus location cite the generally thinnest adipose layer between skin and fascial planes, closer proximity to the lower uterine segment, greater ease of delivery of the neonate, and less traction by the panniculus on the healing incision line. Patients generally prefer the site with the least risk for complications. For some women, the improved cosmesis of the subpannus incision is an advantage, while others are concerned about their inability to visualize the healing surgical site without assistance.

Techniques to lift the panniculus for a subpannus transverse incision include retraction by assistants or, more practically, with a sling of adhesive silk tape or a Montgomery strap, which then affixes to the operating table²³ (Figure 21-2). Communication with the anesthesia team is important in gauging the effect of additional weight on the upper abdomen and lower chest on the patient’s comfort and respiratory mechanics.