The increasing obesity rate in Australia is causing a burden to the health system, as managing these patients is a medical and surgical challenge. In this article, I aim to provide some practical tips that may make the surgical management of these patients easier, and hopefully improve patient outcomes.
Class 1: BMI 30 to ≤35
Class 2: BMI 35 to ≤40
Class 3: BMI ≥40
Waist circumference is another measure of health that is useful in clinical practice. WHO reports a waist circumference greater than 94 cm for men and 80 cm for women as a marker for increased risk of chronic disease.3
In 2014/15 six million Australian adults (36 per cent) were overweight and 5 million were regarded as obese. This equated to 27.4 per cent of female adults, an increase from 18.9 per cent in 1995.4 The average waist circumference for women in 2015 was reported to be 87.5 cm.4
Waist/hip ratio (WHR) is also a useful method to assess obesity. A WHR greater than 0.85 indicates abdominal obesity rather than the more typical female distribution over sub-umbilical areas, hips and thighs.5 This central obesity can be particularly challenging to operate on.
A review of 159 025 benign hysterectomies from the American College of Surgeons National Safety and Quality Improvement Program from 2005–16 showed that abdominal hysterectomy carried a 17 per cent increased risk of morbidity for class 1 obesity, 55 per cent increase for class 2 and 163 per cent higher for class 3 obesity. Only class 3 obese laparoscopic patients experienced a significant increased morbidity when compared to patients of normal BMI.6
In addition to the surgical challenges, obesity is also associated with type 2 diabetes, cardiovascular disease, breast and endometrial cancers, and increased mortality.7 These patients have a four-fold increase in pre-existing conditions when compared to patients of normal BMI.8
A prospective study using the Danish Hysterectomy Database over five years compared complications from 20 353 women having benign hysterectomies and found obesity was associated with increased risk of bleeding, infection and re-operation after open hysterectomy.9 A number of studies found the increase in postoperative complication rate and morbidity associated with obesity has not been observed after laparoscopy, but only after laparotomy;10 11 12 13 though there is some evidence to the contrary.14
When awake, the diaphragm and intercostal muscles can act against the weight of thoracic and abdominal fat; however, with muscle relaxation the compensation is lost and the lungs are subjected to this weight. The resultant effect is a fall in transpulmonary pressure in dependent lung regions, atelectasis of the posterior segments of the lower lobes, decrease in end expiratory lung volume, reduction of respiratory compliance and increased airway resistance. The addition of pneumoperitoneum displaces the diaphragm cephalad, thereby increasing atelectasis, reducing functional residual capacity, decreasing respiratory compliance and increasing airway resistance, compounding the effects of obesity. Trendelenburg increases peak inspiratory pressure, reduces respiratory compliance and impairs arterial oxygenation.15 Gynaecological surgery on obese patients combines two of these factors, and all three if minimally invasive surgery is performed. Therefore, gynaecological surgery on obese patient poses a number of anaesthetic issues.
As a result, surgery on bariatric patients should only be undertaken with the aid of a multidisciplinary team comprising a surgeon, anaesthetist, physician, intensivist, surgical nurses and allied health staff, including physiotherapist, dietitians and psychologist. Hospitals that undertake surgery on obese patients require appropriate infrastructure – that includes bariatric operating beds and ward furniture – and must be adequately staffed. Mobilising a morbidly obese patient postoperatively can require two or three people and, if inadequate, can be an occupational health and safety risk to staff and possibly cause injury to the patient.
As obese patients have increased comorbidities, a thorough medical history is essential. Special attention should be placed on whether patients are on oral anticoagulation therapies, as bridging with enoxaparin or unfractionated heparin may be required, or on a sodium-glucose co-transporter-2 (SGLT2) inhibitor, which will require cessation up to three days pre-op.16 Medical input should be sought to optimise co-existing conditions.
If pathology allows for a delay in surgery, a weightloss program should be undertaken with the aid of a dietitian and psychologist. Even a pre-operative weightloss of a few kilos can reduce the liver volume that can be useful in the retraction of bowel from the pelvis. As these patients can have airways that are difficult to intubate, an anaesthetic review is required. I think that some form of bowel preparation is useful in reducing rectal and sigmoid volume, thereby aiding exposure in the pelvis. This can be achieved with rectal medications and will not cause fluid or electrolyte imbalances that can occur with oral mechanical bowel prep.
Mode of surgery
A number of studies report less intra-operative and postoperative complication when bariatric patients are treated via a minimally invasive approach rather than via laparotomy;17 18 19 20 however, I think that it is important to individualise the management based on pathology, comorbidities, previous surgery, degree of head down that can be achieved and fat distribution. A very high WHR may make a vaginal operation or a laparotomy via a transverse suprapubic incision more feasible than a laparoscopic approach. The surgeon should also play to their strengths and apply the technique they are most comfortable and experienced with.
Consideration should be given to a hybrid operation, where aspects of different modalities can be incorporated. If vault closure is too difficult laparoscopically due to instrument reach or exposure, close it vaginally. A laparoscopic hand port can be used to make laparoscopic surgery easier. A diagnostic laparoscopy can be performed to confirm no bowel adhesions to uterus or adnexa prior to a vaginal hysterectomy. Securing the infundibular-pelvic ligaments laparoscopically then proceeding to a vaginal hysterectomy and bilateral salpingo-oopherectomy will minimise the amount of time required in Trendelenburg position. The options are numerous and should be tailored to the individual patient and pathology. Anaesthetic considerations will also play a role in the mode of surgery. If insufficient Trendelenburg can be achieved, then a laparotomy or vaginal operation would be preferred.
Operating theatre requirements
A bariatric operating table with ability to attach side extensions and bariatric strips are vital. Care should be taken to confirm that the fulcrum of the bed is under the patient’s pelvis, so the head is lowered rather that the pelvis raised when Trendelenburg position is applied. Just as head-down position assists access to the pelvis, lateral tilt should be considered to help expose the pelvic sidewalls.
Crepe bandage applied to the arms and thighs can help secure excess tissue and prevent injury. Care should be taken to prevent pressure areas. Ergonomics of the operating theatre are important, and surgeon injury can be reduced with standing platforms and adequate retractors. Long operating instruments, a head light for an abdominal and vaginal surgery and bariatric laparoscopic ports and instruments will also assist in making for a successful operation.
A retrospective review of 3757 patients undergoing vaginal, lap-assisted or total lap hysterectomies for benign pathology between 2005 and 2012 reported shorter operative time with vaginal hysterectomy, regardless of uterine size and BMI21, suggesting that vaginal surgery is extremely useful in this cohort
Suturing the labia majora laterally, and at times the tissue over to mons pubis cephalad, with interrupted sutures, or taping the panniculus cephalad or laterally, and the use of a Lone Star retractor (endotherapeutics) will aid exposure. Due to difficult access, consider use of an advanced electrosurgical device to allow pedicles to be secured and divided in a single manoeuvre.
Minimally invasive surgery
In a retrospective cohort study comparing non-obese, obese and morbidly obese patients, Peng et al report no difference in conversion rate and complications, but longer operative time, suggesting laparoscopy on obese and morbidly obese patients is safe and feasible.22
Minimally invasive surgery can only be successful with a reasonable degree of head down; therefore, non-slip mattresses, such as memory foam, are important. I avoid bean bags as they can cause pressure areas and make application of a self-retaining retractor post to the bed difficult if conversion to laparotomy is required.
Testing Trendelenburg prior to commencing of surgery will give the anaesthetist an indication of ventilation pressures and likelihood of completing the surgery minimally invasively. Regardless, once entry and exposure is established, the operation should continue with the least amount of head down and at the lowest pressure required to provide adequate vision and exposure.
The position of the umbilicus can vary dramatically with obesity. Therefore, only bony landmarks should be relied upon. As a result, I suggest entry at Palmers point, rather than the umbilicus, as the left costal margin serves as a landmark. An oral-gastric tube to decompress the stomach prior to attempting pneumoperitoneum at Palmer’s point is critical to minimise injury to the stomach.
No ideal entry technique has been established and there is no significant difference in terms of safety23; however, Veress entry is associated with higher rate of failed entry, extra-peritoneal insufflation and omental injury24. In obese patients, I prefer Veress needle insufflation or direct optical entry, as Hassan entry in obesity requires a deep, narrow dissection and offers poor vision. It also makes closure difficult, with increased risk of incisional hernia formation.
When attempting to enter the peritoneal cavity with a Veress needle or direct optical entry at Palmer’s point, it is important to introduce the instrument perpendicular to the skin, so it is directed medially. If directed perpendicular to the operating table, it can skim off the side of the peritoneal cavity and remain extraperitoneal. I suggest choosing an entry technique to use when entry is deemed difficult, and use it for all cases so that it is familiar and comfortable, instead of resorting to a rarely used technique in a difficult situation.
The vertical depth from the anterior abdominal wall to intra-abdominal viscera is proportional to intra-abdominal pressure25. An intra-abdominal pressure of 10 mmHg results in 0.6 cm between abdominal wall and intra-abdominal viscera, while an intra-abdominal pressure of 25 mmHg increased this distance to 5.6 cm.26 Tsaltas et al reported no untoward physiological changes at intra-abdominal pressure of 25 mmHg when patients were supine.27 As a result, I think it is reasonable to insufflate to a pressure of 25 mmHg for optical entry and port placements prior to reducing the pressure. I routinely place my first port at Palmer’s point and then request Trendelenburg. This allows assessment of the pelvis and ability to place the remaining ports in areas that will provide maximum benefit, depending on the operation.
Suturing the panniculus to the upper thigh and mons with a number of interrupted silk sutures is useful in reducing the weight of the abdominal wall on the chest, stabilises the abdominal wall and decreases the pressure of the panniculus on the ports, especially the supra-pubicly.
Port placements tend to be more superior in obese patients, as the umbilicus is often at or below the pubic symphysis. The supra-pubic port should never be placed under the panniculus, as the surgeon will have to push against the abdominal wall in order to manipulate the instruments. Additionally, care must be taken not to ‘buttonhole’ when placing the supra-pubic port.
Spending time to mobilise the sigmoid colon ensures that the large bowel can be retracted out of the pelvis and mobilising the ceacum aids retracting the small bowel from the pelvis. Applying an Endoloop® ligature to an appendices epiploicae and retrieving the thread via the Palmer’s point port or an Endo Close™ will help with retraction of the colon. Endoscopic fan retractors can also be helpful, especially for small bowel retraction.
Do not be concerned about introducing additional ports if it helps with access and triangulation of tissue. The benefit of minimally invasive surgery will not be lost with a few extra ports, but certainly will if there is conversion to a laparotomy. Uterine manipulators effectively provide an extra hand and are a must if performing a hysterectomy or require retraction of the uterus. Advanced vessel sealing devices will minimise instrument changes. Ureters can be difficult to see along pelvis sidewalls in obese patients, and ureteric stents can be used to aid their identification. Skeletonising pedicles prior to their division can reduce the risk of ureteric injury further.
If the overlying bladder is making closure of the vault difficult, and the assistant is required to retract bowel, the bladder can be sutured to the abdominal wall via a straight needle passed supra-pubicly. If the abdominal wall is too thick to introduce the straight needle, the bladder can be sewn intracorporeally and the suture retrieved supra-pubicly using an Endo Close. Alternatively, a T’Lift® can be used. The AirSeal® insufflator is useful in minimally invasive surgery on bariatric patients as it reduces pressure fluctuation and can allow for surgery at lower pressures.
Generally, the Da Vinci robotic surgical platform requires more Trendelenburg; however, often lower pressures can be used, as the robotic arms tend to support the anterior abdominal wall. The articulated instruments provide a greater range of motion and are ideal for operating in a confined space, while reach to the pelvis is rarely an issue. Reduced surgeon fatigue is another advantage of the robotic platform.
A meta-analysis of 51 observational studies involving 10 800 obese patients with endometrial cancer report a laparoscopic conversion rate of 6.5 per cent, a robotic conversion rate of 5.5 per cent at BMI more than 30, and 7.0 per cent and 3.8 per cent respectively at BMI more than 40. Inadequate exposure was reported as the most common reason for conversion. Patients not able to tolerate Trendelenburg were identified in 31 per cent of laparoscopic conversions, but interestingly, only in 6 per cent of robotic conversions.28 This study revealed no difference in complication rates between laparoscopic and robotic surgery on obese patients.
Robotic surgery offers a shorter learning curve,29 no reported difference in complications across BMI groups;30 31 and shorter hospital stay and less blood loss when compared to open surgery.32 Therefore, it may be an ideal option for lower volume surgeons choosing to operate on bariatric patients. At closure, I suggest an Endo Close needle to ensure adequate closure and minimise hernias of all port sites 10 mm or greater.
Again, bony landmarks should be used to decide on position of incisions at laparotomy. As with laparoscopy the incision, transverse or longitudinal, needs to be more superior than on patients of normal BMI. Sutures can again be used to stabilise and retract the panniculus and avoid transverse incisions under the panniculus due to difficulty with wound care and risk of infection.
Self-retaining retractors are vital to achieve adequate exposure and reduce assistant fatigue. The addition of an Alexis® retractor is useful in reducing the width of the abdominal wall so the surgeon can get closer to the operative field. It also serves to stabilise the abdominal wall so tissue does not protrude around retractor blades.
As with laparoscopy, spending time to mobilise and reflect the bowel will pay dividends, vessel-sealing devices and ureteric stents are useful and the principle of skeletonising pedicles to minimise injury to surrounding tissue holds true. A BMI greater than 30 is an independent risk factor of incisional hernias,33 so meticulous care should be taken when closing the rectus sheath.
A Cochrane review found that uncertainty remains as to whether negative pressure wound therapy reduced mortality, dehiscence or seroma formation when applied in a prophylactic setting.34 Despite this, I have a low threshold to consider a drain in the adipose layer or a negative pressure dressing. Skin should be closed with interrupted sutures or staples that can be removed in the event of a wound infection.
An intensive care admission is often required postoperatively. Ongoing involvement of medical teams to treat co-existing conditions, especially maintaining tight blood glucose control, is important. Medical and mechanical thromboprophylaxis will reduce thrombo-embolic events and have low threshold for prolonged thromboprophylaxis.
Continued input form dietitians and physiotherapists for chest physiotherapy and mobility aids recovery, and as long as no bowel surgery has been performed, I encourage early feeding and mobilisation as per enhanced recovery after surgery (ERAS) protocol.35