Obesity & Pregnancy - An Ultrasound Challenge - SD

Introduction and Objectives

Hello, I'm Dr. Glance and we're going to spend this session speaking about obesity and pregnancy and ultrasound challenge.

Our objectives for this session, which will be split in two, will be to look at the impact of obesity and pregnancy.

What are the population statistics?

What are the increased maternal and fetal risks?

How does it affect quality of patient care?

The limitations of ultrasound tips and tricks that we can use, ergonomic issues.

And finally, the future of imaging in the obese pregnant patient.

Global and US Statistics on Obesity

The World Health Organization has called obesity a crisis.

Obesity is a major killer disease of the millennium on par with HIV and malnutrition.

It is the sixth most significant cause of ill health worldwide, but one of the most neglected world health problems.

This is a global paradox where we are seeing the two extremes of nutrition coexisting, both malnutrition and overnutrition.

The World Health Organization considers obesity to be a pandemic.

The definition of an epidemic is when the prevalence has reached a critical threshold greater than 15%, and a pandemic is where this threshold is reached Worldwide.

Over 1 billion overweight people exist worldwide at this point in time.

In the United States, 64.5% of the population is considered to be overweight or obese.

9 million adults are categorized as being morbidly obese.

When we look at the reproductive age group, more than 40% of women in the United States would now fall into the category of overweight or obese.

This is a chart which looks at global obesity, where obesity is defined as a body mass index, or BMI greater than 30.

This is the list of the top 30 with the arrow pointing where the United States falls.

If one looks at the bar graphs, the greens are consistently higher than the blues, and this represents the female population, which clearly has a worldwide trend to be afflicted by obesity to a greater degree than the male population.

Obesity trends among American adults have gradually increased from 1990 to 1995 into 2005, moving from the blues where the obesity rates were below 15% into the oranges, where they are 20%, the darker oranges 25 to 30% and the speckled oranges greater than 30%.

Similarly, in Canada, we have seen trends of increasing in the percentage of overweight and the categories within obesity.

Canadians classify 35% of their population is currently being overweight and 15% as obese.

Obesity in Pregnancy: Definition and Risks

So when we come back to thinking of obesity in pregnancy, in fact, obesity is now the commonest clinical risk in obstetric practice, and obesity is a major risk factor for maternal death with 35% of all maternal deaths occurring in obese patients.

What is obesity? We define obesity most typically by using a equation called the body mass index, which is weight typically in kilograms over height meters in meters squared.

The dividing line is A BMI of 30 below 31 would be overweight above 30, entering obese with class one being 30 to 35 BMI, class two obesity, 35 to 40 BMI and class three obesity.

BMI over 40 characterized as morbidly obese.

From a very practical perspective, this would typically represent 90 kilograms or 200 pounds.

For those who are not keen on doing math, quick math equations.

One can use chart graphs like this where we plug in the height against the weight and determine which category the patient falls into the definition of obesity.

The actual BMI ratio is one way of looking at it, but obesity in fact may not be the disease.

Obesity is a symptom of a condition which has been referred to as the metabolic syndrome and in many ways is a tip of the iceberg to what is going on in the patient's body.

What is obesity?

Although the definition of BMI or Body Mass Index has given us actual numbers to work with obesity, perhaps really belongs to this syndrome called the metabolic syndrome.

The World Health Organization has defined this as any one of the characteristics on your left.

Type two diabetes, insulin resistance or impaired glucose tolerance would define the syndrome or any two on the right.

Hypertension, obesity, dyslipidemia, and micro albuminuria.

Polycystic ovarian disease is considered by many to be a component of the metabolic syndrome.

Reproductive Challenges

Being an obese pregnant patient, brings the patient into serious reproductive challenge.

An elevated BMI even in the overweight category is a risk for subsequent ovulatory infertility.

The infertility risk with A BMI over 30 has a likelihood ratio of approximately 2.7.

In addition, there's increased fetal wastage with infertility therapy.

So a double challenge for reproduction.

In the obese population, 30% of obese women have polycystic ovarian syndrome and this is now the most common cause of endocrine infertility.

These patients also experience higher rates of fetal loss with a miscarriage risk of 1.2 and a recurrent miscarriage risk of 3.5.

There have been many therapies tried to restore fertility with the most successful, ultimately being weight loss, even small weight loss amounts.

Oral hypoglycemics in particular, Metformin is quite helpful and newer techniques such as the one on the image on your bottom left ovarian drilling with oscopy techniques where they perform micro perforations in the surface of the ovary to try and induce ovulation.

Bariatric Surgery

Another direction which has been utilized to try and improve fertility is bariatric or weight loss surgery.

In fact, bariatric surgery is felt to be the only known effective long-term treatment for obesity.

Early weight loss may result in unplanned pregnancies and it is recommended to advise the patient to wait one to two years until the weight loss stabilizes.

As in any surgery, life-threatening complications can occur with the more common postoperative complications being gastrointestinal bleeds, malabsorption, or bowel obstruction.

Typically, outcomes during pregnancy are generally quite good in patients who have undergone weight loss surgery.

These surgeries are not recommended in the overweight category or class one or two, but in patients who are morbidly obese with A BMI greater than 40 or A BMI between 35 and 40, but with associated health problems,

Maternal and Fetal Risks

pregnancy and obesity carries risks both maternal and fetal.

The maternal risks, the more common among them are gestational diabetes, preeclampsia diabetes mellitus, hypertension, cardiac disease, and venous thromboembolic disease.

In Class one, as we progress to class two and three, the relative risk increases as one might expect for each of these diseases.

There are other risks associated with obesity, but these are the most commonly quoted ones.

Perhaps more interestingly are the fetal risks.

Congenital anomalies are increased in the obese population with a risk ratio of 1.8 in class one, increasing to 3.3 in class two.

And three. Other risks include macrosa, birth trauma, most commonly shoulder dystocia, still birth and increased neonatal intensive care admissions.

These are most commonly related to problems with hypoglycemia and hyper, hyper bilirubin.

Delivery Challenges

The obese pregnant population also experiences increased problems at delivery.

There is a 1.2 to three times increased risk of cesarean section, both primary and emergency.

Because of the increased operative rates, these patients are at increased risk for both peri and postoperative complications such as blood loss, hospitalizations and postoperative infections.

When we think about postoperative infections, the classic cesarean surgery that is performed at that this time is a horizontal incision rather than a vertical incision.

And this is being chosen because it, there is less pain unless risk of ventral hernia occurring postoperatively.

However, in these patients because of the overhanging panis, there is an increased risk of wound infections.

There is also an increased risk of deep venous thrombosis.

Obesity and pregnancy are independent risk factors for the development of deep venous thrombosis and pulmonary thrombo embolus.

Patients are encouraged to attempt a vaginal delivery after a prior cesarean section.

There is a very high failure rate in the obese population at these temps and it is believed that this is related to altered labor physiology as well as physician unwillingness to attempt a vaginal delivery after C-section.

Given the potential complexities of an unplanned cesarean section.

Case Study

The following case will illustrate some of the points that we have been talking about.

The patient is a 27-year-old gravita one para zero who was transferred to our institution for third trimester care.

She has been so-called heavy since childhood as are her family members and partner throughout her pregnancy.

She has remained normal glycemic.

The estimated fetal weight on a 36 week ultrasound was 5,000 grams.

The patient declined a trial of labor after extensive discussion and opted for planned daytime cesarean section.

Her rationale for declining a trail, trial of vaginal labor was to avoid the concerns about the time that might be required for an emergency C-section to occur and to avoid the risks of birth trauma.

Her preoperative consultations included cardiac, pulmonary and anesthetic complications.

This is an image of the woman being marked on her back for epidural anesthesia.

Four anesthetists were ultimately involved in her case planning the epidural anesthesia.

There were three initial failed epidural attempts despite the use of ultrasound to localize the non palpable um disc spaces.

When the patient was placed supine, the epidural catheter repetitively dislodged as the soft tissue shifted as the patient went from an upright to a supine position.

Nonetheless, epidural anesthesia was persistently tried until success.

And the reason for this is that general anesthesia is avoided where possible in this population due to an increased morbidity on the basis of failure to secure safe airways.

These patients also require higher ventilation settings to maintain oxygenation, which can ultimately lead to barrow trauma.

Special monitoring is required.

The blood pressure cuffs typically do not reliably read blood pressure on the larger arms and arterial lines are inserted for monitoring vital signs.

A special or table is required to accommodate the weight of the patient and the total time in this case was five hours.

And this explains why this patient would opt for a preplanned cesarean section rather than attempt a trial of labor vaginally as an emergency C-section may require many hours to set up safely within the operating room itself.

There are many challenges, the most considerable of which is dealing with the panus and the question that's always debated is whether to lift or not lift the panus in the image.

In your lower right, we see a different patient who we were able to successfully tape back the panus permitting a transverse incision to occur.

However, in patients who are over 350 pounds, as was this patient, the panus can be quite heavy and the retraction of it onto the chest may cause pulmonary problems and difficulties with ventilation.

And so in this case, the harness straps were vertically hooked to the ceiling in order to lift the panties away and permit adequate visualization for surgery.

The outcome was a 6,100 gram baby, essentially healthy, but recognizing how far off our estimated fetal weight was in this case, our charts do not go reliably at this size.

Implications of Fetal and Neonatal Obesity

What are the implications then of fetal and neonatal obesity?

In maternal obesity?

Mom tends to gain more weight and is less successful at losing that weight with the resultant associated health.

Issues of more concern is the next generation

Childhood obesity is predicted by genetic and environmental factors.

With the maternal BMI having a greater influence than paternal BMI social and environmental influences also come into play.

These babies are at increased risk to eventually develop the metabolic syndrome and as adults they are at a nine times increased risk for adult obesity.

The US growing up today study looked at a 14,000 adolescent cohort population and found a 50% increase in overweight in the ages of nine to 14 per kilogram increment of birth weight.

At full term, there still remained a 30% increase risk of being overweight after adjusting for maternal BMI so that a macrosomic or large for gestational age baby, even without a large BMI mother remains at significant increased risk for developing into an obese adolescent.

Why does this occur when the mother is affected by either obesity or the metabolic syndrome or experiences hyperglycemia?

This is translated through the placenta to the fetus who experience increased levels of glucose to which the fetus will respond by hyperinsulinemia.

It is believed that this resets the CNS appetite regulation centers possibly in a permanent fashion leading to future hyperphagia or overeating impaired glucose tolerance and obesity with an eventual reset in the hypothalamic insulin resistant centers, which in turn will alter neurotransmitter production for satiety and again, leading us back to maternal obesity and the metabolic syndrome, a very hard cycle for any individual to break out of.

Planning for the Future

So when we think of planning for the future in this population, we are concerned with pre-pregnancy planning.

As we decrease the weight of the patient, the risk will decrease.

So nutrition, counseling, exercise and folic acid supplementations are important and consideration of bariatric surgery involving the patient and her partner in the planning can be important to avoid some of the psychosocial issues of the increased risk of anxiety and perceptions that weight may interfere with the quality of the relationship with the healthcare system and the family.

And the patient needs to understand what her increased risks and challenges will be throughout the pregnancy and certainly it requires increased understanding and communication of the special challenges for the sonographers and the healthcare workers involved in the team.

Thank you very much.

Part Two: Obesity, Pregnancy, and Ultrasound Challenges

Hello, this is Dr. Glance again.

We're going to come back to the topic of obesity and pregnancy and ultrasound challenge part two.

We're going to focus now on maternal obesity and ultrasound.

Patient Positioning

The challenge before going ahead and looking at the ultrasound itself, I would like to comment on the position our patient should be in in when sharing the ultrasound suite with us,

the patient on your left weighs approximately 350 pounds pregnant, the patient on your right, approximately 150 pounds while pregnant.

Both are term patients being set up for cesarean section and one can imagine that the patient on your left, the 350 pound patient, is at significant risk for aorta caval compression if she remains supine on her back.

And so we recommend strongly that when these patients are initially in the ultrasound suite with you, that you encourage them to move into an oblique position, a decubitus position or a semi recumbent position to decrease the risk of aortic caval compression and improve pulmonary mechanics to avoid the potential hypoxemia and hypotension.

We have found that many of these patients are hesitant to complain that they're feeling unwell as they already perceive that they're causing difficulties within the healthcare system because of their weight.

So careful observation and continued interaction with the patient is important.

Basic Imaging Tips

Going back to the very basic imaging tips, our basic elements remain the same.

The organ of interest in this case, the fetus must fit into the focal range of the transducer.

The organ should be large enough for optimal viewing and the organ should be fully developed for assessment.

So what can we offer in the larger patient?

Well, the closer the better is a very basic caveat and scanning through the umbilicus, the thinnest part of the umbilical wall can bring the patient and the fetus several centimeters closer to the imaging probe.

Scanning below or above the panas can be very helpful.

Unlike in the operating room, we do not have the luxury of taping the panis away.

However, we can certainly ask the patient and her partner to help retract the panis for us as we scan and placing the patient in a lateral decubitus position so that the panis falls forward in a way is also helpful in bringing the fetus closer to the transducer.

An illustrative example of the closer, the better this image is performed, scanning through the panis and just by moving the transducer to the umbilicus, we've come in several centimeters closer, which has dramatically improved the image.

Equipment Optimization

Know your equipment.

In all our patients in ultrasound, it is quite important to be aware of our equipment and the various options which are available for us.

However, in the larger patient, optimizing the features can become critical in being able to finalize and complete an anatomic survey.

Frequency is an important choice.

The lower the frequency, the greater the distance.

The ultrasound waves can travel, but the lower your resolution.

And so these are trade-offs.

Currently, the lowest megahertz transducers on the market are in the one megahertz range.

A narrowing the sector width will increase the scan lines per centimeter.

Improving our resolution, repositioning the transducer to improve scan angles and avoid reverberation artifacts or shadowing can be helpful.

And certainly post-processing tools which vary from manufacturer to manufacturer can help us improve our images.

Harmonic imaging and spatial compound imaging are two of the newer innovations in ultrasound that have had a tremendous effect on improving imaging.

And I encourage you to utilize these two particularly harmonic imaging to improve the gray scale contrast and spatial compounding for speckle reduction and improvement of margin definition.

A graphic illustration of of four simple neology bits.

We're looking at the same cross-section through the abdomen, anterior placenta large patient, and we'll just switch four knobs on the first to the second.

All we've done is put our focal zone into the optimal position.

The optimal place for a focal zone will vary from equipment manufacturer to manufacturer.

So knowing that with your own equipment is important.

We've now added the harmonics and improved our gray scale contrast and now added spatial compound imaging.

And so by these very rapid steps, which take seconds, we have gone from the upper left hand image to the bottom right hand image where we now have beautiful definition of the portal veins, the stomach, the subcutaneous tissues, the posterior elements just by simple ology.

Optimal Timing for Anatomic Survey

What is the optimal timing in which to do an anatomic survey In the underweight category, the completion rate at 15 to 18 weeks is equal to that of 18 to 20 weeks.

So any time becomes a good time in an unselected population, the completion rate will progressively increase as we go from 18 to 22 weeks.

What about in the obese population?

There, there are studies in the literature which suggests that transabdominal studies should not even be attempted prior to 20 weeks due to poor completion rates.

Other studies have demonstrated that minimal or no improvement with advancing gestation or duration of equipment, will occur with BMI in and of itself being the best predictor of suboptimal visualization rates.

Studies on Visualization Rates

Do patients with BMI greater than 30 actually require more exams to complete anatomy evaluations?

We looked at our own population in a retrospective study of 100 consecutive cases with A BMI greater than 30 matched with two normal weight controls performed in the same institution on the same day, in the same week gestational age range.

And what we found was what you might expect the controls are on your left and the greater than 30 BMI population on your right repeat scans were very rarely required and almost all patients in the control group were able to complete anatomy with satisfactory visualization.

Looking at this numerically in the greater than 30 BMI population, approximately 26% required a repeat examination versus 2.5% in the control population.

We were able to complete the anatomy surveillance in only 74% of the larger patients, but almost a hundred percent of controls.

And similarly, visualization was satisfactory in only 28%, moderate in 46% and poor in 26% of those with larger BMI.

Whereas 88.5% of control population had satisfactory visualization.

Interestingly, the commonest indication for recall was similar in both populations with heart and spine being the most difficult areas to complete In the anatomic survey,

Maternal Obesity and Birth Defects

maternal obesity and birth defects, birth defects will increase as the patient's BMI increases.

The mechanism for this is unknown, but it is clear from various studies that although the individual numbers will vary from study to study, it is consistently found that there are increased risks for congenital anomalies of which neural tube defects, spina bifida and and encapsulate are one of the most consistently identified.

And this is independent of folate supplementation.

One of the best studies in the literature looking at this was published by MERS at AL in 1998.

They looked at over 20,000 newborn babies in the city of Maines in patients with A BMI greater than 30.

They found that the prevalence of malformation in children of obese mothers was approximately 11.1%, 4% higher than that of the total study population.

And again, you can appreciate that the odds ratio for many malformations was increased with the highest odd ratios for specific entities being efile, common truncus, arteriosis, and the potter sequence.

And when they adjusted for maternal diabetes and age, there was no significant change in the odds ratios

In obese women then we deal with the issue of increasing BMI with an associated progressive increase in the risk of birth defects as the body mass index increases accompanied by a decreased detection rate of those anomalies and decreased visualization on ultrasound,

advancing gestational age or prolongation of the exam or repeat examinations may not help visualization in the general population.

80% of common structural abnormalities are present by 12 weeks with virtually all present by 15 to 16 weeks.

So perhaps there's a role for an early anatomic survey.

If we think about this a little more carefully, even at 18 weeks, many of the central nervous system structures have not yet fully developed.

The cerebellum and the corpus callosum are not fully developed until 20 to 22 weeks.

And the Garry and sci continue to develop into third trimester.

And many studies demonstrate that heart structures are better seen after 20 weeks gestational age.

In fact, there are many entities that are late developing such as hydronephrosis, ventricular magaly, micro microcephaly, certain skeletal dysplasias, GI obstructions, and other entities.

In fact, in some patients, no matter what you do, we will have a difficult examination.

And here on your left is a CT examination of a 42-year-old female who weighs only 265 pounds.

She has massive ascites, which we're thinking of as simulating the amniotic fluid of pregnancy.

When we put the probe on this patient, we cannot see beneath the subcutaneous fat layer.

So for some patients, at no time during the pregnancy would a transabdominal examination be successful for a fetal anatomic survey.

So again, we consider that the early anatomic survey by a transvaginal sonogram may in fact be the only time possible in certain patients for a satisfactory window for imaging.

There are no studies currently in the literature to look at optimal timing in the obese population.

Learning Curve for Transvaginal Sonography

Okay, the learning curve for detecting selected fetal major structural defects by transvaginal sonography was carefully looked at by Ty palatal at 13 to 40 weeks.

They surveyed over 23,000 consecutive women.

And what they found in their study was their sensitivity in year one for detection of major fetal structural defects was only 22% and it took until year six to achieve a stabilization and a sensitivity of 79%.

So their suggestion is that transvaginal sonography as a mechanism for detection of major fetal structural defects in an anatomic survey may require an extremely long learning curve.

I think that many of us feel that our learning curves may not take that long, but perhaps the take home point would be that it does take time and skill to develop and ultimately our sensitivity can approach the 18 to 22 week examination.

Case Illustration: Transvaginal vs. Transabdominal

The following case, will illustrate the appearances between the 15 week transvaginal anatomic examination versus a conventional 20 week examination performed.

Transabdominally, this is a 37-year-old patient, a gravity of five, para two, abor two who has a BMI or body mass index of 40 just entering class three or morbid obesity.

The image on your left is performed at 15 weeks.

Transvaginally the image on your right, the same plane of imaging at 20 weeks transabdominal.

And I think it is quite clear the exquisite detail, the stomach outline, the easy ability to visualize the abdominal aorta, the spinous structures, and the liver as compared to, although this is all present, somewhat difficult to clearly delineate.

Similarly, at 15 weeks on your left, the kidneys are easily seen with clear cortico medullary distinction and somewhat grayer and less distinct by transabdominal sonography at 20 weeks.

When looking at the heart, the images by transvaginal sonography are exquisite in demonstrating the four chamber view and the outlet views, although quite satisfactory transabdominally as well.

And then looking at the facial profile, again, more detailed by the transvaginal sonogram.

This was a 10 pound, 10 ounce baby, a 4,500 grand baby who delivered spontaneously.

The comparison of these two sets of image again suggest anecdotally that there may be a role for early anatomic transvaginal sonography in this group of patients at around 15 weeks.

Again, there are no studies in the literature to support this.

Ergonomics for Sonographers

I wanna switch gears a little bit now and look at ultrasound, an occupational hazard.

How do we keep everyone happy?

We have many patients who are large and overweight becoming pregnant and wanting that same happy pregnancy that any pregnant patient would desire.

And then we have our sonographic team who look at these patients and have concerns about their own physical wellbeing.

Well, what can we do to satisfy both sides of this equation?

We have very basic do's and don'ts, ergonomically speaking.

And these are the ones that I think most of us are familiar with and work with on a daily basis.

The top image is your don'ts and the bottom is your dues.

And here we see that the sonographer has straightened her spine, brought the patient in closer to her, so she is not reaching across the angle between her shoulder and her arm is less than 30 degrees.

She has lowered the table and elevated the chair to place herself in an optimal ergonomic position.

And this is something we should be doing all the time with all of our patients.

One of the other areas that are very important is what's called the pinch grip versus the power grip.

The pinch grip, which many of us use in daily scanning only utilizes 25% of our total grip strength.

We recommend that you use a power grip as we see the hand and thumb position on your right hand side, which utilizes all of our hand muscles and will decrease strain.

Having said that, although we use these basic strategies, the reality of maternal obesity and the sonographer is that in many cases additional strategies are required.

It is very difficult to avoid awkward positions and a lot of depressing is required for a lengthy period of time.

What are the additional strategies?

Special tables can be very helpful that permit the patient to get up.

Unassisted adjustable equipment in particular height, adjustable equipment for the chairs, the tables, lightweight cables and scan design that helps you to minimize the pinch grip.

Voice command equipment can be useful in that it may permit one to work from the opposite side and decrease.

Reaching more frequent breaks at least every 10 minutes can be quite important where we stand up, stretch, relax.

And finally, non-consecutive or task rotation is critical.

The team approach enlisting the patient and her partner is very useful.

The patient can reposition for you, lift the panas for you.

And perhaps most importantly of all, understand the need for increased time and breaks required for the sonographer during a challenging examination.

Economics of Ergonomics

What are the economics of ergonomics?

80% of sonographers will experience work-related musculoskeletal pain with 20% eventually suffering a career ending injury.

We have a critical shortage of healthcare professionals.

There are a number of risk factors which are identified, as leading to work-related musculoskeletal injuries.

The and in the obese population in particular, we have the added concern of repetitive, forceful, or awkward motions ex, the duration of heavy pressure that's required and excessive force and strain that's being utilized.

So significantly increased risk of dealing with this population.

What is the solution?

Education, ergonomic equipment where possible, and taking personal responsibility for aggressively applying good ergonomic work practices at all times with the ultimate reward being a healthy sonographer.

Future Directions and Conclusion

So what is the optimal timing?

We believe in the future that the combination of biochemistry, nal, translucency, and early fetal anatomic scans will ultimately be considered state-of-the-art in screening In all pregnancies in the obese patient, we feel it may be the only viable alternative and should be considered.

Industry has been working hard to respond to the increased obesity trends worldwide.

And as you can appreciate, the columns in white are the old weights, pounds and kilograms of the conventional machinery.

And the new equipment coming out is going up to tables that can accommodate seven hundred, six hundred and eighty five fifty and 550 pounds.

And similarly, the apertures or opening of these equipments have increased from 45 to 60, 70 to 90 and so forth to accommodate the increasing obesity trends in the ultrasound field.

We have not seen much advancement, however.

So in conclusion, how is obesity affecting our population?

We will be treating more and more patients who are obese and pregnant in the ultrasound suite.

How does obesity impact on mother in the fetus?

More patients with complications and adverse fetal outcomes will be part of our population.

How does obesity complicate obstetric ultrasound?

There are greater technical challenges.

There is a greater risk of anomalies and we wanna consider what the optimal timing of the anatomic ultrasound should be in this population.

There is an impact of on quality of care.

The patient's self-image and access to care may be adversely affected by their obese state.

Suboptimal visualization and inaccurate estimated fetal weights, as we saw in the large 6,100 gram infant may limit the physician ability to counsel and manage care.

And finally, and most importantly, the impact on the health of the sonographers physical and emotional wellbeing may be adversely affected.

Industry awareness is leading to new technical developments, which may aid in the delivery of patient care and imaging.

Medical advances are continually acting to improve medical and surgical care.

These patients in particular, bariatric or weight loss surgery has been helpful.

And social awareness of the epidemic of obesity is leading to increased research and fund allocation for education and prevention.

Thank you very much.