Introduction

Caesarean birth in patients with a significantly elevated body mass index (BMI) presents several clinical challenges to achieve safe outcomes. These encompass preoperative anaesthesia, surgical, and postoperative considerations. Many of these challenges are predictable and therefore can be mitigated by careful planning, in partnership with the patient and their family, in the antepartum period. The overall process of birth becomes considerably easier when the team anticipates problems with maternal positioning and exposure of the gravid uterus, with a willingness to adapt a standardised approach to the individual patient.

An important principle is that BMI does not define surgical anatomy, nor does it correlate with surgical complexity. Two patients with the same BMI may have very different distributions of adipose tissue, panniculus anatomy, previous abdominal incisions, and relationships between the overlying subcutaneous tissues and the gravid uterus. Surgical planning should therefore be individualised, based on the patient’s findings, and taking into consideration their preferences, rather than a BMI threshold alone.

Preoperative Surgical Planning

Preparation begins with multidisciplinary team planning in the antepartum period, ideally within a dedicated clinical program which includes the patient’s preferences and expectations in birth planning. Patients identified >50 kg/M2 in our program are referred for an obstetric anaesthesia assessment, where specific resources such as  modification of the operating table with additional positioning aids, consideration of patient transfers, appropriately sized sequential leg compression devices, appropriate experienced surgical assistance, and availability of specific surgical tools (exposure devices, modified instruments, specific sutures, negative pressure skin incision system).¹ Our teams ensure patients receive appropriately fitted hospital gowns for their comfort.

Positioning should optimise respiratory mechanics, airway access, and surgical exposure, while avoiding excessive pressure or traction. The panniculus should be examined preoperatively in the supine position when obtaining surgical consent, and reviewed with the patient positioned for surgery, aided by preoperative assessment of the subcutaneous fat distribution. This assessment process is used to answer one of the most important preoperative questions, which is where should the surgical incision be placed?

Antibiotic prophylaxis should be administered before skin incision according to local caesarean protocols, with dose increases indicated by patient weight. Postoperative thromboprophylaxis should similarly be modified according to local risk-assessment guidelines.¹˒² The patient is usually positioned supine with a 15-degree lateral tilt, similar to routine caesarean birth, with side extensions as needed for stability and patient safety.

Choosing the Skin Incision

A Pfannenstiel incision remains appropriate for many patients with elevated BMI, made easier to use with a panniculus elevating device such as a Traxi. However, a large dependent panniculus may result in chronically moist skin with local inflammation at this site, such that a conventional low transverse incision will likely incur a high risk of subcutaneous and skin infection despite preventive measures.

In such cases, options include a higher transverse incision above the panniculus, 2-3cm below or above the umbilicus (Video 1), or a vertical midline incision above or around the umbilicus. No single incision approach is appropriate for every patient. Our team utilises point of care perioperative ultrasound as an important adjunct to surgical planning in determining the optimal incision location for access to the uterus, with the goal of easy fetal extraction and minimised risk of postoperative wound complications (Figure 1A and 1B). This technique involves palpating the anterior-superior iliac spines, then identifying the anterior abdominal anatomical region that corresponds to this level, giving access to the lower uterine segment. Ultrasound, avoiding excessive pressure, is then utilised to scan superior and inferior to this area to identify the shortest distance from the skin to the lower uterine segment.

Fig. 1A

Fig. 1B

Figs. 1A and 1B. Perioperative assessment with examination and ultrasound for planned supra-umbilical transverse incision to facilitate supra-pannicular lower uterine segment access. Still images from TVASurg video, reproduced with permission.

Observational evidence generally associates transverse incisions with fewer wound complications than vertical incisions when placed higher than usual in patients with obesity. These decisions are largely via surgeon preference, in conversation and collaboration with the patient and their preferences. A systematic review that included 17 studies found vertical incisions were associated with approximately twice the risk of wound complications compared with higher transverse incisions in patients with obesity.³ More recent data have also challenged the assumption that a high transverse incision necessarily reduces wound morbidity.⁴

Incision choice should therefore incorporate panniculus anatomy, previous abdominal incision, anticipated location of the uterus, prior deliveries by CS, additional potentially-distorting anatomy (especially fibroids), the need to repair an umbilical hernia, required surgeon experience, and the possibility that a high abdominal entry may necessitate a non-standard uterine incision.

A Case in Point

Our Toronto Video Atlas of Surgery (TVASurg.com) demonstration of caesarean birth in a patient with BMI 70 illustrates one approach to challenging surgical anatomy (Video 1). ⁵ The patient had one previous caesarean birth and elected for repeat caesarean delivery.

Because of the large dependent panniculus, a supra-umbilical transverse skin incision was selected using ultrasound mapping. This is not intended as the default incision for patients above a particular BMI. Rather, the case demonstrates the value of selecting an incision that provides direct, controlled access to the abdominal wall and lower segment of the uterus.

The complete operative video is available through the Toronto Video Atlas of Surgery and can complement the techniques illustrated here (Video 1).

Abdominal Entry: Exposure is the Key to Success

After dividing the subcutaneous tissue, abdominal wall anatomy may differ considerably from that encountered in patients with less adipose tissue.

In our case, the rectus fascia was stretched substantially, and the rectus muscles were displaced laterally (Figure 2A).⁵ This changes the surgical relationship with the inferior epigastric vessels (Figure 2B). A gently curved transverse fascial incision was therefore created while maintaining a safe distance from the lateral rectus muscles and epigastric vessels.

Once the peritoneal cavity was entered, a flexible, self-retaining surgical retractor provided excellent exposure of the operating field (Figure 2C).⁵

This illustrates an important and broader surgical principle: a longer incision is often safer than a deeper struggle through an inadequate one. An incision that is “minimally invasive” but provides poor visualisation may increase tissue trauma, make haemostasis difficult, and complicate fetal extraction. Adequate exposure allows anatomy to be identified and permits the remainder of the caesarean to proceed in a controlled fashion.

Fig. 2A. Fascial entry demonstrating lateral displacement of the rectus muscles. Still image from TVASurg video, reproduced with permission.

Fig. 2B. Fascial entry demonstrating lateral displacement of the rectus muscles and the anatomical location of the inferior epigastric arteries. Still image from TVASurg video, reproduced with permission.

Fig. 2C. Abdominal retractor providing uterine exposure. Still image from TVASurg video, reproduced with permission.

Hysterotomy and Delivery

Once the uterus is adequately exposed, the principles of fetal delivery should remain familiar. In our case, a transverse lower-segment hysterotomy was performed. The fetal head was flexed and gently elevated towards the incision while maintaining the fetal caudal-cranial axis, with appropriately directed fundal pressure assisting delivery. ⁵

This again demonstrates why exposure is the key element of elevated BMI surgical cases. Difficulty reaching the presenting part can tempt the surgeon or assistant to compensate with greater fundal pressure. Increasing force through inadequate access is rarely the best solution. If fetal extraction is challenging, reassess the size of the abdominal and uterine incisions and the fetal position before applying progressively greater force. A two-handed approach to facilitating delivery of the fetal head can also be useful (Video 1).

Closure is as Important as Exposure

Wound complications increase with elevated BMI, making meticulous closure particularly important.⁶ Secure fascial closure is essential, and awareness that if facial entry is located above the arcuate line, both anterior and posterior facial layer closure is required. The use of barbed sutures may facilitate this stage. When substantial subcutaneous tissue is present, closing the dead space in layers, again with standard or barbed sutures, is vital and may reduce wound disruption by more effectively closing the dead spaces.¹˒⁶ The use of barbed sutures for the fascia, adipose, and subcuticular layers helps to maintain even tension across the tissues. Skin closure is achieved with a subcuticular monofilament suture.

Our video concludes with application of prophylactic negative-pressure wound therapy (Figure 3).⁵ Systematic reviews and meta-analyses have shown that negative pressure wound therapy compared to routine dressings significantly reduces surgical site complications in elevated BMI caesarean section and that some specific products may have advantages over others.^6,7

Fig. 3. Completed layered closure and negative-pressure dressing. Still image from TVASurg video, reproduced with permission.

Postoperative Debriefing and Planning Following Skin Closure

Patients living with obesity have increased postpartum venous thromboembolism risk, particularly following caesarean birth. Early mobilisation, mechanical prophylaxis, and pharmacological thromboprophylaxis when indicated should form part of the perioperative plan.² Respiratory care, multimodal analgesia, consideration of additional antibiotics, and a practical plan for wound inspection are also important.

Patients should receive the same thoughtful postoperative communication offered after any complex surgery. An elevated BMI should not be allowed to become shorthand for either surgical difficulty or an adverse outcome.

Five Practical Principles

For caesarean birth in patients with elevated BMI, the following principles are important foundations to ensure safe, high-quality care:

1. Plan around maternal and uterine anatomy, not BMI alone, in collaboration with the patient.
2. Position first and choose the incision intentionally.
3. Make the incision large enough to extract the fetus safely.
4. Good exposure reduces the need for force and thus the risk of uterine extensions.
5. Close all layers meticulously and individualise postoperative care.

Elevated BMI does not inherently make caesarean birth unsafe. The greatest opportunities to improve safety lie in preparation, adequate exposure, adaptable surgical technique, and attention to postoperative risk.

Video 1. Video on elevated BMI caesarean birth, created by TAV Surg at the University of Toronto.

Acknowledgements: Dr Eliane Shore, Dr Mara Sobel, and the team at TVASurg for their generous permission of the use of figures and videos.