DENVER – In current practice, the majority of superobese pregnant women – those having a prepregnancy body mass index of 50 kg/m2 or more – will end up having a cesarean section. The inherent technical challenges make it crucial to have a plan in place before heading to the operating room.
"There’s a lot to think about: patient positioning, choice of incision, antibiotic prophylaxis, deep vein thrombosis prophylaxis, wound care," Dr. Mark Alanis observed at the annual meeting of the Society of Ob/Gyn Hospitalists.
Also, it’s important to understand up front that one in three of these superobese patients will have a significant wound complication. Eighty-five percent of these are cellulitis or wound disruptions, mostly seromas, which will require packing. But one in seven of the wound complications are abscesses, and affected superobese patients require hospital readmission, said Dr. Alanis of the University of Colorado, Denver.
He presented lessons learned from his own retrospective study of 194 superobese patients who underwent cesarean section, plus several studies by other investigators. Among the highlights:
• Anesthesia evaluation. Bring the anesthesiologist in on the case early. Finding the landmarks for spinal anesthesia is tough in a superobese patient. Failed regional anesthesia is more common. In Dr. Alanis’ series, general anesthesia was required in 15% of patients – a far higher rate than in leaner women – so a careful preoperative airway assessment is essential.
• Patient positioning. Understand that positioning the superobese patient at a 20-degree tilt puts the midline far away from the surgeon, who’ll have to operate bending forward. "My back is killing me when I do these operations," the ob.gyn. said.
• Choice of incision. Dr. Alanis recommends the Pfannenstiel incision. This horizontal incision is faster than a vertical incision, the wound hurts less, healing is better, and the classic teaching that it poses an increased risk of infection in massively obese patients is a myth unsupported by data.
The key is to first mobilize the panniculus, moving it up off the suprapubic region, then securing it with a Montgomery strap tied off to the bedposts.
"It takes 5 minutes to secure the pannis. It’s the easiest thing in the world, and you don’t need an assistant for the operation once it’s done," he explained.
• Operative characteristics. The mean skin-to-delivery time in Dr. Alanis’ series was 15 minutes, with an incision-to-closure time of 64 minutes and an estimated blood loss of 1,000 mL, all considerably greater than in leaner patients.
In another investigator’s study involving 193 superobese women, the incision-to-delivery time was nearly identical at 16 minutes, and the fetal distress rate as measured by cord pH, Apgar score, and neonatal ICU admission was significantly higher than in patients with a lower body mass index (Am. J. Obstet. Gynecol. 2013;209:386.e1-386.e6).
This increased risk of fetal distress was confirmed recently in a study from the National Institutes of Health Maternal-Fetal Medicine Units Network. The analysis of 5,742 mother/singleton term neonate pairs delivered by prelabor cesarean section demonstrated that fetal distress increased with greater body mass index category. For every 10-unit increase in BMI, the cord arterial pH decreased by an adjusted value of 0.01 and the base deficit increased by 0.26 mmol/L. The relationship wasn’t linear, though; the steepest increase in fetal distress was seen in women with a prepregnancy BMI of 40 kg/L or more (Obstet. Gynecol. 2013;122:262-7).
"We want these women to deliver vaginally, but be cognizant that it’s going to take longer to take that woman to the OR, and it’s going to take longer to get that baby out," he observed.
• Antibiotic prophylaxis. A major practice trend in the past several years has been a shift to routine administration of preincision antibiotics.
• Deep vein thrombosis prophylaxis. Two-thirds of postsurgical DVTs are deemed preventable. The risk in pregnancy jumps from a fourfold increase with vaginal delivery over that in daily life, to a 13-fold increase with cesarean delivery, to a 26-fold increase with emergent cesarean section – and emergent cesarean section is considerably more common in superobese patients than in those of lesser BMI. Also, a BMI of 40 or more is an independent risk factor for DVT.
Dr. Alanis strongly recommends having an order set in place. While the risk of postpartum hemorrhage climbs with increasing BMI, this is not due to the use of anticoagulation. Nor does anticoagulation in superobese patients undergoing cesarean section raise their risk of hematoma or wound complications, he added.
• Wound closure. An audience show of hands indicated a strong preference for subcutaneous closure. Dr. Alanis said that’s probably fine for patients who are merely overweight, but in the superobese – women who often have 5-10 cm of subcutaneous thickness – it doesn’t improve the risk of seroma. He believes retention sutures are a good idea that hasn’t been well studied. Subcutaneous drains proved to be a bust in his study, as well as in every other study ever published.