The Morbidly Obese Parturient: Comorbidities, Complications, and Considerations
This PBLD was peer-reviewed by a panel of experts from the Society of Obstetric Anesthesia and Perinatology (SOAP) and has been endorsed by the SOAP Education Committee.
Required Pre-work:
- Lamon AM, Habib A. Managing anesthesia for cesarean section in obese patients: current perspectives. Local and Regional Anesthesia. 2016; 9:45-57.
- Obesity in Pregnancy. Committee Opinion No. 549. American College of Obstetricians and Gynecologists. Obstet Gynecol. 2013; 121:213-7.
- Tonidandel A, Booth J, D’Angelo R, Harris L, Tonidandel S. Anesthetic and obstetric outcomes in morbidly obese parturients: a 20-year follow-up retrospective cohort study. Int J Obstet Anesth. 2014;23(4):357-64.
Learning Objectives:
Upon conclusion of this session, the fellow will be able to:
- Discuss the classification system of obesity and the common comorbidities associated with obesity in pregnancy.
- Describe the anticipated anesthetic challenges of the obese parturient.
- Discuss the current literature regarding the incidence of failed intubation in the parturient and how obesity may impact intubation difficulty.
- Describe current timing and dosing recommendations for antibiotic prophylaxis for cesarean delivery and strategies to minimize wound infections.
CASE: A 25-year-old morbidly obese (body mass index (BMI) = 52 kg/m2) G1 P0 patient at 37 + 3 days gestational age, with no previous prenatal care, is being admitted to the labor and delivery floor for spontaneous rupture of membranes.
The patient’s vital signs are:
Pulse = 88 bpm
BP = 145/97
O2 saturation on room air = 97%
Temperature = 37 degrees Celsius.
The patient has told the nurse that she is otherwise healthy, other than “I am just big, that is all.”
According to the World Health Organization (WHO) classification of obesity, a pre-pregnancy BMI of 34.5 kg/m2 would be considered which of the following categories:
According to the World Health Organization (WHO) classification of obesity, a pre-pregnancy BMI of 34.5 kg/m2 would be considered which of the following categories
One-third of women aged 20-39 in the United States are classified as obese, with a BMI greater than 30 kg/m2.1 Various definitions of obesity exist in the literature, and different criteria (pre-pregnancy weight vs. 10-14 weeks GA weight vs. term weight) have been used in studies, making it more difficult to draw conclusions from the literature.2
Classic definitions using pre-pregnancy BMI include
Normal weight = 18.5-24.9 kg/m2
Overweight = 25-29.9 kg/m2
Obesity = >30 kg/m2
The WHO has further categorized obesity into three categories:
Class 1: BMI 30-34.9 kg/m2
Class 2: BMI 35-39.9kg/m2
Class 3: BMI >40kg/m2
Although not within this classification system, BMIs > 50 kg/m2 are generally categorized as super-morbid obesity.3
With a BMI of 52kg/m2, this patient is at risk of all of the following labor complications EXCEPT:
With a BMI of 52kg/m2, this patient is at risk of all of the following labor complications EXCEPT
In a population-based study by Weiss et al., which included over 16,000 patients, patients were categorized into three groups
BMI < 30kg/m2
BMI = 30-34.9kg/m2 (obese)
BMI > 35kg/m2 (morbidly obese)
Parturients with a BMI > 30kg/m2 were more likely than normal-weight peers to develop:
- Pre-eclampsia (odds ratio (OR) = 1.6 in obese patients, 3.3 in morbidly obese)
- Gestational hypertension (OR = 2.5 in obese patients, 3.2 in morbidly obese)
- Gestational diabetes (OR = 2.6 in obese patients, 4.0 in morbidly obese)
- Fetal birth weights over 4000grams (a risk factor for shoulder dystocia)
- Cesarean delivery
- Stillbirth
In addition, maternal obesity is also a risk factor for anesthesia-related maternal mortality and complications from cardiovascular disease and thromboembolism.5 Finally, obese patients are more likely to have either sleep-disordered breathing or obstructive sleep apnea.
Fetal complications of obese mothers include recurrent first-trimester losses, stillbirth (especially with a comorbidity of gestational diabetes mellitus), congenital malformations (including neural tube and genitourinary defects), macrosomia, neonatal hypoglycemia, shoulder dystocia, and large for gestational age.6-8
In addition, obese women may have longer labor compared to non-obese peers. The first stage of labor may be prolonged, but increasing body mass was not associated with increased duration for the second stage of labor.9-11
Considering the patient received no prenatal care, what information would you deem most important to know about this patient in order to properly assess her? (Try to list 5-10 maternal/obstetric history, physical exam, or laboratory findings)
Considering the patient received no prenatal care, what information would you deem most important to know about this patient in order to properly assess her? (Try to list 5-10 maternal/obstetric history, physical exam, or laboratory findings)
- Maternal vitals
- Fetal heart tracings
- Airway exam
- Fetal presentation
- Anesthetic history (including previous intubation)
- Obstetric history
- Medical history (including allergies)
- Preeclampsia labs (platelets, LFTs)
- Vascular access
- Blood glucose level
The obstetrician’s vaginal exam reveals a soft cervix with fingertip dilation, and rupture of membranes is confirmed. The patient is comfortable and reports that she does feel some mild contractions. The external tocodynamometer is unable to consistently provide contraction tracings. The fetal heart rate tracings is categorized as category 1 when the nurse is able to trace the fetus. The fetus is confirmed to be in cephalic presentation.
Due to a lack of prenatal care, no previous prenatal laboratory values or fetal anatomy ultrasounds are available.
Admission laboratory values are as follows: Hgb – 12.1gm/dL, platelets – 172k, AST = 20, ALT = 15, no protein is appreciated in the urine, P/C ratio is pending, blood glucose = 222gm/dL. Immunological titers are within normal limits, and the drug screen is negative. Group-beta streptococcus is unknown.
Presuming the glucose has been poorly controlled during her pregnancy, this patient’s fetus is at an increased risk of which of the following conditions::
Presuming the glucose has been poorly controlled during her pregnancy, this patient’s fetus is at an increased risk of which of the following conditions:
Fetuses of diabetic mothers have a significantly increased risk of death and morbidity. These risks may be due to prolonged exposure to intrapartum hyperglycemia, hyperinsulinemia, and hypoxia-ischemia.14 Our patient did not receive prenatal care, and her fetus may be at risk for morbidity.
Fetuses of diabetic mothers have an increased risk of:14
- Stillbirth
- Death within the first week of life
- Congenital abnormalities including:
Cardiac (ventricular septal defects and hypertrophic cardiomyopathy)
Neural tube defects
Anomalies of the limbs
Connective tissue defects - Neonatal polycythemia due to insulin-induced glucose uptake– (which can
lead to neonatal jaundice as red cells are lysed as well as hyperviscosity syndrome) - Neonatal hypoglycemia (neonate will have an increased production of
insulin, decreased hepatic glucose production, and lipolysis) - Large for Gestational age and macrosomia
- Preterm delivery
- Intrauterine growth restriction
- Hypocalcemia and hypomagnesemia
- Birth trauma (shoulder dystocia, head trauma, brachial plexus injury, and fractured clavicle)
According to ACOG recommendations, at what estimated fetal weight should a patient with gestational diabetes be given the option for a scheduled cesarean delivery compared to a vaginal delivery?:
According to ACOG recommendations, at what estimated fetal weight should a patient with gestational diabetes be given the option for a scheduled cesarean delivery compared to a vaginal delivery?
According to the 2013 practice bulletin from The American College of Obstetrics and Gynecology (ACOG), macrosomia and shoulder dystocia are more common for a given fetal weight in patients with gestational diabetes. Therefore, the ACOG recommends providing patients with gestational diabetes and an estimated fetal weight of greater than 4500 gm an option of scheduled cesarean delivery.15 For patients without gestational diabetes, a scheduled cesarean delivery can be offered if the estimated fetal weight is greater than 5000 gm.
The obstetrician reports to you that the plan is to augment the patient’s labor with oxytocin. The estimated fetal weight is 4000g.
You interview the patient who has no known allergies, takes no medications, reports no significant PMH or previous surgeries, denies drug, alcohol, or tobacco use, and has no family history of anesthesia complications. The patient reveals that she last ate breakfast 3 hours ago and has limited functional status (she can do basic chores but “does not do stairs”).
You would like to examine the patient. What are the key components of your exam?
You would like to examine the patient. What are the key components of your exam?
- Airway (Mallampati classification, thyromental distance, cervical range of motion, mouth opening, circumference of neck, ability to prognathate)
- Back examination
- Cardiac exam
- Lung exam
- Edema in lower extremities
- IV check (what gauge and flow)
The patient has a Mallampati III class airway with a thyromental distance of 6cm, full cervical range of motion and a wide mouth opening. Her neck is relatively short. Her heart and lung exams are normal but distant due to her body size.
The patient tells you that the obstetrician told her today that she needs to get an epidural because she is at high risk of having a cesarean delivery. The obstetrician also told her that the epidural may be more difficult to place, and she would like to know why.
Which one of the following items most predicts difficulty in epidural placement for obese patients?:
Which one of the following items most predicts difficulty in epidural placement for obese patients?
Ellinas et al. performed a prospective study of neuraxial placement and found that obesity by itself was not predictive of difficult epidural placement. The inability to palpate landmarks and decreased ability of the patient to flex her back were predictive of difficulty in placement.16
What difficulties and complications are more common during epidural placement in an obese patient relative to a non-obese parturient?
What difficulties and complications are more common during epidural placement in an obese patient relative to a non-obese parturient?
After your discussion with the patient, she states she will think about it but does not want to get the epidural now. She does agree to sign the consent forms.
The nurse starts the oxytocin augmentation, and one hour later, the nurse calls the obstetrician to the room. The fetal heart tones demonstrate late decelerations but are difficult to trace. A vaginal exam is performed, and the patient’s cervix is 2cm dilated. Internal fetal monitors are placed, which confirm intermittent fetal late decelerations with good variability between contractions. Intrapartum resuscitation is performed with maternal oxygen, left uterine displacement, a fluid bolus, and the oxytocin is discontinued. Contraction monitoring indicates intermittent contractions.
Two hours later, the patient’s cervix is dilated 4cm and 50% effaced. Again, the oxytocin infusion is started to augment contractions, but fetal decelerations occur again. After discussion with the patient, the decision for cesarean delivery is made.
What special equipment should or might you have available to take care of a morbidly obese parturient in the operating room (OR)?
The patient is positioned in the operating room, and after 40 minutes and the use of ultrasound, the obstetric anesthesia providers are unable to successfully place an epidural catheter. The patient is frustrated and states, “Enough, I just want to be put to sleep.” At the same time, the fetal heart tones become concerning with multiple late decelerations. You make the decision to proceed with general anesthesia.
What special equipment should or might you have available to take care of a morbidly obese parturient in the operating room (OR)?
- OR bed that accommodates bariatric patients
- Longer spinal and/or epidural needle
- Advanced airway equipment
- Positioning ramp or blankets
- Large Blood Pressure cuffs
- Ultrasound for neuraxial placement or IV access
- Arterial line if unable to get accurate noninvasive BP readings
What physiological and anatomical factors make pregnant airways more challenging than nonpregnant peers?
What physiological and anatomical factors make pregnant airways more challenging than nonpregnant peers?
Many factors make the pregnant airway more challenging.19-20
Increased weight gain during pregnancy
Increased anterior-posterior diameter of the chest due to progesterone relaxation of the intercostal ligaments – results in misalignment of the oral, pharyngeal, and tracheal axes
Increased oxygen consumption leads to more rapid oxygen desaturation
Increased breast mass – may impede placement of laryngoscope (necessitating use of short handle laryngoscope)
Edema of the upper airway due to pregnancy– narrowing upper airway
More friable tissues and blood vessels due to progesterone influence
Progressive swelling during labor21
In addition, her morbid obesity increases her likelihood of undiagnosed obstructive sleep apnea, which may make emergency mask ventilation as well as intubation more difficult.
Historically, general anesthesia has been considered to be much more dangerous than regional anesthesia. Overall, general anesthesia is relatively safe for the parturient. In a review of anesthesia-related 1985-2003 maternal deaths in Michigan, Mhyre et al. demonstrated that maternal deaths in the peripartum period were more associated with airway obstruction and hypoventilation in obese patients following extubation and general anesthesia emergence rather than during intubation. This may indicate that postoperative monitoring of immediately postpartum patients who received general anesthesia is an important part of safe care.5. Some evidence suggests that video laryngoscopes may have a role in obstetric intubations and improve outcomes.20
How would you anticipate that the patient’s obesity would impact her planned intubation?
After pre-oxygenation, general anesthesia is induced via rapid sequence and the airway is secured with an endotracheal tube. The surgeon requests antibiotics but is concerned about fetal exposure and asks you to hold the cefazolin until after the cord is clamped.
How would you anticipate that the patient’s obesity would impact her planned intubation?
- Obesity has been associated with increasing difficulty with laryngoscopy
- Obesity, like pregnancy, decreases the overall FRC (both RV and ERV are decreased), and therefore, the patient will have less oxygen reserve than non-obese peers due to the upward pressure on the diaphragm due to the panniculus.
- Increasing tissue mass increases oxygen consumption, which will result in faster desaturation with apnea
- Arterial blood gas demonstrates more hypoxemia in obese patients when compared to non-obese
- Obesity is associated with OSA and may result in difficult mask ventilation.
Which one of the following statements is TRUE regarding antibiotic administration for cesarean deliveries?:
Which one of the following statements is TRUE regarding antibiotic administration for cesarean deliveries?
The use of prophylactic antibiotics for cesarean delivery is well established and should be administered prior to skin incision compared to after cord-clamping27. For cefazolin, the target tissue levels for gram-positive cocci is greater than 1 mcg/gm tissue and 4mcg/gm tissue for gram negative rod prophylaxis. The pharmacokinetics of antibiotics may differ in pregnant women due to physiological changes, including an increase in glomerular filteration rate, an increased volume of distribution, and a decrease in plasma proteins.28 Elkomy et al. demonstrated that cefazolin clearance increases 74% during pregnancy, and cefazolin is rapidly transferred across the placenta.29 This study examining the pharmacokinetics of cefazolin administration in women undergoing scheduled cesarean delivery and their neonates found that a 2gm administration of cefazolin administered within an hour of surgery produces effective blood concentrations in both maternal and cord blood.
Current best practices for antibiotic dosing for obese parturients is controversial, and no current guidelines exist, although several studies have indicated that obese patients may require higher doses of antibiotics.30 Stitely et al. examined plasma and tissue cefazolin concentrations in obese patients (BMI >35kg/m2) and found that a prophylactic dose of 2gm of cefazolin was adequate to produce the recommended target tissue levels.31 However, Pevzner et al. demonstrated that 2 gms cefazolin surgical prophylaxis did not reliably produce therapeutic tissue concentrations in extremely obese patients (BMI > 40kg/m2).30 Further studies may be needed to elucidate antibiotic regimens for the extremely obese parturient.
This patient is at high risk for subsequent development of wound infection. Which of the following strategies is effective in reducing wound infections for obese patients?:
This patient is at high risk for subsequent development of wound infection. Which of the following strategies is effective in reducing wound infections for obese patients?
Wound infection following cesarean delivery is common and may be more common in obese women.32 In addition, the combination of obesity and diabetes (either gestational or pregestational) may significantly increase the risk of developing wound infections and wound dehiscence.33 The skin thickness of the wound also seems to play a role in the development of infection, with skin thickness >3cm being associated with higher infection rates. In addition, suture closure of wounds reduces the rate of wound separation and wound morbidity compared to skin closure with staples.34 Neither the administration of high concentrations of supplemental oxygen nor the placement of prophylactic surgical drains has been shown to reduce rates of infection or wound morbidity. The type of incision (vertical vs. transverse or supraumbilical vs. infraumbilical) has not been definitively shown to contribute to the development of wound infections.
The patient undergoes an uneventful general anesthetic for her cesarean delivery. She is extubated and taken to the recovery room. Her recovery is uncomplicated, and she is discharged on postoperative day 3.
References
- Flegal KM, Carroll MD, Kit BK, Ogden CL. Prevalence of obesity and trends in the distribution of body mass index among US adults, 1999-2010. JAMA : the journal of the American Medical Association. 2012;307(5):491-7.
- Gunatilake RP, Perlow JH. Obesity and pregnancy: clinical management of the obese gravida. American journal of obstetrics and gynecology. 2011;204(2):106-19.
- Obesity: preventing and managing the global epidemic. Report of a WHO consultation. World Health Organization technical report series. 2000;894:i-xii, 1-253.
- Weiss JL, Malone FD, Emig D, Ball RH, Nyberg DA, Comstock CH, et al. Obesity, obstetric complications and cesarean delivery rate–a population-based screening study. American journal of obstetrics and gynecology. 2004;190(4):1091-7.
- Mhyre JM, Riesner MN, Polley LS, Naughton NN. A series of anesthesia-related maternal deaths in Michigan, 1985-2003. Anesthesiology. 2007;106(6):1096-104.
- ACOG Committee opinion no. 549: obesity in pregnancy. Obstetrics and gynecology. 2013;121(1):213-7.
- Macumber I, Schwartz S, Leca N. Maternal obesity is associated with congenital anomalies of the kidney and urinary tract in offspring. Pediatric Nephrology. 2016:1-8.
- Huang HY, Chen HL, Feng LP. Maternal obesity and the risk of neural tube defects in offspring: A meta-analysis. Obesity research & clinical practice. 2016.
- Robinson BK, Mapp DC, Bloom SL, Rouse DJ, Spong CY, Varner MW, et al. Increasing maternal body mass index and characteristics of the second stage of labor. Obstetrics and gynecology. 2011;118(6):1309-13.
- Carlhall S, Kallen K, Blomberg M. Maternal body mass index and duration of labor. European journal of obstetrics, gynecology, and reproductive biology. 2013;171(1):49-53.
- Tonidandel A, Booth J, D’Angelo R, Harris L, Tonidandel S. Anesthetic and obstetric outcomes in morbidly obese parturients: a 20-year follow-up retrospective cohort study. Int J Obstet Anesth. 2014;23(4):357-64.
- ACOG Practice Bulletin. Clinical Management Guidelines for Obstetrician-Gynecologists: number 41, December 2002. Obstetrics and gynecology. 2002;100(6):1389-402.
- Practice Guidelines for Obstetric Anesthesia: An Updated Report by the American Society of Anesthesiologists Task Force on Obstetric Anesthesia and the Society for Obstetric Anesthesia and Perinatology. Anesthesiology. 2016;124(2):270-300.
- Hawdon JM. Babies born after diabetes in pregnancy: what are the short- and long-term risks and how can we minimise them? Best practice & research Clinical obstetrics & gynaecology. 2011;25(1):91-104.
- Practice Bulletin No. 137: Gestational diabetes mellitus. Obstetrics and gynecology. 2013;122(2 Pt 1):406-16.
- Ellinas EH, Eastwood DC, Patel SN, Maitra-D’Cruze AM, Ebert TJ. The effect of obesity on neuraxial technique difficulty in pregnant patients: a prospective, observational study. Anesthesia and analgesia. 2009;109(4):1225-31.
- Whitty RJ, Maxwell CV, Carvalho JC. Complications of neuraxial anesthesia in an extreme morbidly obese patient for Cesarean section. Int J Obstet Anesth. 2007;16(2):139-44.
- Ring LE. The anesthetic approach to operative delivery of the extremely obese parturient. Seminars in perinatology. 2014;38(6):341-8.
- Soens MA, Birnbach DJ, Ranasinghe JS, van Zundert A. Obstetric anesthesia for the obese and morbidly obese patient: an ounce of prevention is worth more than a pound of treatment. Acta anaesthesiologica Scandinavica. 2008;52(1):6-19.
- Scott-Brown S, Russell R. Video laryngoscopes and the obstetric airway. Int J Obstet Anesth. 2015.
- Kodali BS, Chandrasekhar S, Bulich LN, Topulos GP, Datta S. Airway changes during labor and delivery. Anesthesiology. 2008;108(3):357-62.
- Practice guidelines for obstetric anesthesia: an updated report by the American Society of Anesthesiologists Task Force on Obstetric Anesthesia. Anesthesiology. 2007;106(4):843-63.
- Hawkins JL, Chang J, Palmer SK, Gibbs CP, Callaghan WM. Anesthesia-related maternal mortality in the United States: 1979-2002. Obstetrics and gynecology. 2011;117(1):69-74.
- Lyons G. Failed intubation. Six years’ experience in a teaching maternity unit. Anaesthesia. 1985;40(8):759-62.
- D’Angelo R, Smiley RM, Riley ET, Segal S. Serious complications related to obstetric anesthesia: the serious complication repository project of the Society for Obstetric Anesthesia and Perinatology. Anesthesiology. 2014;120(6):1505-12.
- Bamgbade OA, Khalaf WM, Ajai O, Sharma R, Chidambaram V, Madhavan G. Obstetric anaesthesia outcome in obese and non-obese parturients undergoing caesarean delivery: an observational study. Int J Obstet Anesth. 2009;18(3):221-5.
- Sun J, Ding M, Liu J, Li Y, Sun X, Liu T, et al. Prophylactic administration of cefazolin prior to skin incision versus antibiotics at cord clamping in preventing postcesarean infectious morbidity: a systematic review and meta-analysis of randomized controlled trials. Gynecologic and obstetric investigation. 2013;75(3):175-8.
- ACOG Practice Bulletin No. 120: Use of prophylactic antibiotics in labor and delivery. Obstetrics and gynecology. 2011;117(6):1472-83.
- Elkomy MH, Sultan P, Drover DR, Epshtein E, Galinkin JL, Carvalho B. Pharmacokinetics of prophylactic cefazolin in parturients undergoing cesarean delivery. Antimicrobial agents and chemotherapy. 2014;58(6):3504-13.
- Pevzner L, Swank M, Krepel C, Wing DA, Chan K, Edmiston CE, Jr. Effects of maternal obesity on tissue concentrations of prophylactic cefazolin during cesarean delivery. Obstetrics and gynecology. 2011;117(4):877-82.
- Stitely M, Sweet M, Slain D, Alons L, Holls W, Hochberg C, et al. Plasma and tissue cefazolin concentrations in obese patients undergoing cesarean delivery and receiving differing pre-operative doses of drug. Surgical infections. 2013;14(5):455-9.
- Tipton AM, Cohen SA, Chelmow D. Wound infection in the obese pregnant woman. Seminars in perinatology. 2011;35(6):345-9.
- Schneid-Kofman N, Sheiner E, Levy A, Holcberg G. Risk factors for wound infection following cesarean deliveries. International journal of gynaecology and obstetrics: the official organ of the International Federation of Gynaecology and Obstetrics. 2005;90(1):10-5.
- Mackeen AD, Schuster M, Berghella V. Suture versus staples for skin closure after cesarean: a metaanalysis. American journal of obstetrics and gynecology. 2014.
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