Appropriate dose of prophylactic antibiotics

The prophylactic use of antibiotics in women undergoing CS has been shown in randomised controlled trials (RCTs) to reduce the incidence of wound infections (RR 0.39; 95% CI 0.32–0.48), puerperal endometritis (RR 0.38; 95% CI 0.34–0.42) and serious maternal infectious complications (RR 0.31; 95% CI 0.19–0.48) . When administered before skin incision, as opposed to intraoperative administration after cord clamping, it has been shown to decrease puerperal endometritis (RR 0.59; 95% CI 0.37–0.94) , with a non-significant trend towards a reduction in wound infections (RR 0.71; 95% CI 0.44–1.14). Cephalosporins and penicillins seem to have similar efficacy in reducing short-term post-operative infections, although there are limited data on neonatal outcomes and late infections . These studies were carried out in the general CS population and no subgroup analysis of obese patients is available. Doses of 1 or 2 g of intravenous cefazolin were frequently used.

There are ample data from non-pregnant obese patients to suggest that tissue penetration of antibiotics is impaired in this population, and therefore higher doses need to be used for adequate prophylaxis , but it is not clear whether 2 g of cefazolin is sufficient for all BMI classes. In an experimental study evaluating 20 obese patients receiving 2 or 4 g of cefazolin before CS, all collected subcutaneous and myometrial tissue samples had antibiotic concentrations above the minimal inhibitory levels, and no infectious complications occurred . In another series of 29 patients given 2 g of cefazolin 30–60 min before CS, antibiotic concentrations in wound adipose tissues were inversely proportional to maternal BMI and a considerable percentage of women with a BMI >30 kg/m ² did not achieve minimal inhibitory concentrations for gram-negative rods at skin incision, but all reached this level at skin closure .

Although the existing evidence on this subject is still inconclusive, the current data point to the need to administer at least 2 g of cefazolin some 60 min before CS in obese patients. It is possible that this dose is insufficient in women with higher BMIs.

Vertical or transverse skin incision

The choice of skin incision for CS in obese patients is still a matter of controversy, as mixed findings have been reported in observational studies.

In a US hospital cohort of 239 patients with a BMI >35 kg/m ² undergoing their first CS, a vertical skin incision was associated with a higher risk of wound complications requiring reopening of the incision (OR 12.4; 95% CI 3.9–39.3), when compared with a transverse incision . In another US cohort of 623 women with a BMI >35 kg/m ² undergoing primary CS, vertical skin incisions were associated with a fourfold risk of infectious and separation wound complications . In a third retrospective US cohort of 194 patients with a BMI >50 kg/m ² undergoing CS, vertical skin incisions were also associated with an increased risk of wound complications (OR 2.2, 95% CI 1.18–4.27) .

Two studies have reported no difference in wound complications between transverse and vertical skin incisions: a retrospective cohort from the USA of 238 women with a BMI >29 kg/m ² undergoing CS, evaluating partial or complete wound separation , and another retrospective US cohort of 133 women with a BMI >40 kg/m ² undergoing CS, evaluating wound complications in vertical versus Pfannenstiel skin incisions .

On the other hand, a large US retrospective cohort of 3200 women with BMI >40 kg/m ² undergoing primary CS reported a significantly lower rate of wound complications with vertical skin incisions, including infection, seroma, haematoma, evisceration and fascial dehiscence (OR 0.32, 95% CI 0.17–0.62) .

In conclusion, there is conflicting evidence on the benefits of vertical versus transverse skin incisions for CS in obese women. Existing data originate from observational studies that are affected by selection bias, consequent to the motives for choosing the skin incision. An RCT is necessary to clarify this clinical dilemma. Likewise, the choice between a Pfannenstiel and a Joel-Cohen incision in obese patients has not been the subject of investigation. There is some evidence from RCTs to suggest that the Joel-Cohen incision has advantages over the Pfannenstiel incision in the general population, with a reduction in post-operative febrile morbidity (RR 0.35, 95% CI 0.14–0.87), in delivery and operating time, as well as estimated blood loss and post-operative analgesic requirements . In obese patients, however, it is generally easy with Pfannenstiel incisions to dissect the subcutaneous tissue upwards and open the rectus sheath above the pyramidalis muscles, as would occur in the Joel-Cohen incision. In this way, the poorer cosmetic results of the latter are avoided . Direct comparisons between the different skin incisions in obese women are needed.

Closure of the subcutaneous tissue layer

There is a wide body of evidence from the general CS population to support closure of the subcutaneous tissue layer when its depth exceeds 2 cm, and a meta-analysis of six studies has shown that this measure decreases wound complications by 34%, particularly seroma formation . In a subgroup analysis of one of these RCTs, evaluating women with a subcutaneous tissue thickness in excess of 4 cm, closure of this layer was associated with a significant reduction in wound complications.

In conclusion, all findings support closure of the subcutaneous tissue layer when performing CS in obese women.

Drain placement in the subcutaneous tissue

RCTs evaluating CS performed in the general population have found no difference in the incidence of wound complications or any other maternal morbidity when subaponeurotic or subcutaneous drains are left in place, compared to when they are not . One of the trials reported a higher risk of wound infection associated with the use of subcutaneous drains when compared with subaponeurotic drains (RR 5.42, 95% CI 1.28–22.98) . The overall conclusion from this analysis is that the routine use of subcutaneous or subaponeurotic drains during CS does not appear to confer any substantial benefit. However, no sub-analysis in obese women was performed.

In a prospective case–control study conducted in Egypt evaluating 118 women with a BMI >32 kg/m ² undergoing CS with a Pfannenstiel incision, no difference in wound dehiscence or haematoma formation was found between those who had subcutaneous drains and those who did not . In a retrospective US cohort of 194 patients with a BMI >50 kg/m ² undergoing CS, the use of subcutaneous drains was associated with an increased risk of wound complications (OR 2.3 95% CI 1.23–4.38) .

In a multicentre RCT in the USA, 280 women with >4 cm of subcutaneous thickness undergoing CS were randomised to subcutaneous layer closure alone or in combination with subcutaneous suction drainage. The incidence of composite wound morbidity (subcutaneous or fascial dehiscence, seroma, haematoma and abscess) was similar in both groups, as were individual wound complications and hospital readmission rates for this motive .

In conclusion, the existing evidence strongly suggests that the use of subcutaneous drainage during CS in obese women does not reduce the incidence of wound complications.

Closure of the skin

Skin closure in CS is usually performed with subcuticular sutures, interrupted sutures or non-absorbable staples. A systematic review identified eight RCTs evaluating these three alternatives for closure of the Pfannenstiel incision in the general CS population, and found similar incidences of wound complications with staples and subcuticular sutures, as well as similar pain and cosmetic results . Staple removal before the fourth post-operative day was associated with an increased risk of skin separation.

A recent RCT from Egypt compared the incidence of wound complications in 130 obese non-diabetic women, between subcuticular and interrupted mattress skin sutures, both using non-absorbable polypropylene . Subcuticular sutures took lesser time, and were associated with better cosmetic results but more pain. The incidence of wound infection was similar in both groups, but the study was clearly underpowered to evaluate this outcome.

In conclusion, the evidence on which to base the choice of method for skin closure in CS in obese women is limited, but there is little to suggest that it should be different from that of the general population.

Appropriate dose of prophylactic antibiotics

The prophylactic use of antibiotics in women undergoing CS has been shown in randomised controlled trials (RCTs) to reduce the incidence of wound infections (RR 0.39; 95% CI 0.32–0.48), puerperal endometritis (RR 0.38; 95% CI 0.34–0.42) and serious maternal infectious complications (RR 0.31; 95% CI 0.19–0.48) . When administered before skin incision, as opposed to intraoperative administration after cord clamping, it has been shown to decrease puerperal endometritis (RR 0.59; 95% CI 0.37–0.94) , with a non-significant trend towards a reduction in wound infections (RR 0.71; 95% CI 0.44–1.14). Cephalosporins and penicillins seem to have similar efficacy in reducing short-term post-operative infections, although there are limited data on neonatal outcomes and late infections . These studies were carried out in the general CS population and no subgroup analysis of obese patients is available. Doses of 1 or 2 g of intravenous cefazolin were frequently used.

There are ample data from non-pregnant obese patients to suggest that tissue penetration of antibiotics is impaired in this population, and therefore higher doses need to be used for adequate prophylaxis , but it is not clear whether 2 g of cefazolin is sufficient for all BMI classes. In an experimental study evaluating 20 obese patients receiving 2 or 4 g of cefazolin before CS, all collected subcutaneous and myometrial tissue samples had antibiotic concentrations above the minimal inhibitory levels, and no infectious complications occurred . In another series of 29 patients given 2 g of cefazolin 30–60 min before CS, antibiotic concentrations in wound adipose tissues were inversely proportional to maternal BMI and a considerable percentage of women with a BMI >30 kg/m ² did not achieve minimal inhibitory concentrations for gram-negative rods at skin incision, but all reached this level at skin closure .

Although the existing evidence on this subject is still inconclusive, the current data point to the need to administer at least 2 g of cefazolin some 60 min before CS in obese patients. It is possible that this dose is insufficient in women with higher BMIs.

Vertical or transverse skin incision

The choice of skin incision for CS in obese patients is still a matter of controversy, as mixed findings have been reported in observational studies.

In a US hospital cohort of 239 patients with a BMI >35 kg/m ² undergoing their first CS, a vertical skin incision was associated with a higher risk of wound complications requiring reopening of the incision (OR 12.4; 95% CI 3.9–39.3), when compared with a transverse incision . In another US cohort of 623 women with a BMI >35 kg/m ² undergoing primary CS, vertical skin incisions were associated with a fourfold risk of infectious and separation wound complications . In a third retrospective US cohort of 194 patients with a BMI >50 kg/m ² undergoing CS, vertical skin incisions were also associated with an increased risk of wound complications (OR 2.2, 95% CI 1.18–4.27) .

Two studies have reported no difference in wound complications between transverse and vertical skin incisions: a retrospective cohort from the USA of 238 women with a BMI >29 kg/m ² undergoing CS, evaluating partial or complete wound separation , and another retrospective US cohort of 133 women with a BMI >40 kg/m ² undergoing CS, evaluating wound complications in vertical versus Pfannenstiel skin incisions .

On the other hand, a large US retrospective cohort of 3200 women with BMI >40 kg/m ² undergoing primary CS reported a significantly lower rate of wound complications with vertical skin incisions, including infection, seroma, haematoma, evisceration and fascial dehiscence (OR 0.32, 95% CI 0.17–0.62) .

In conclusion, there is conflicting evidence on the benefits of vertical versus transverse skin incisions for CS in obese women. Existing data originate from observational studies that are affected by selection bias, consequent to the motives for choosing the skin incision. An RCT is necessary to clarify this clinical dilemma. Likewise, the choice between a Pfannenstiel and a Joel-Cohen incision in obese patients has not been the subject of investigation. There is some evidence from RCTs to suggest that the Joel-Cohen incision has advantages over the Pfannenstiel incision in the general population, with a reduction in post-operative febrile morbidity (RR 0.35, 95% CI 0.14–0.87), in delivery and operating time, as well as estimated blood loss and post-operative analgesic requirements . In obese patients, however, it is generally easy with Pfannenstiel incisions to dissect the subcutaneous tissue upwards and open the rectus sheath above the pyramidalis muscles, as would occur in the Joel-Cohen incision. In this way, the poorer cosmetic results of the latter are avoided . Direct comparisons between the different skin incisions in obese women are needed.

Closure of the subcutaneous tissue layer

There is a wide body of evidence from the general CS population to support closure of the subcutaneous tissue layer when its depth exceeds 2 cm, and a meta-analysis of six studies has shown that this measure decreases wound complications by 34%, particularly seroma formation . In a subgroup analysis of one of these RCTs, evaluating women with a subcutaneous tissue thickness in excess of 4 cm, closure of this layer was associated with a significant reduction in wound complications.

In conclusion, all findings support closure of the subcutaneous tissue layer when performing CS in obese women.

Drain placement in the subcutaneous tissue

RCTs evaluating CS performed in the general population have found no difference in the incidence of wound complications or any other maternal morbidity when subaponeurotic or subcutaneous drains are left in place, compared to when they are not . One of the trials reported a higher risk of wound infection associated with the use of subcutaneous drains when compared with subaponeurotic drains (RR 5.42, 95% CI 1.28–22.98) . The overall conclusion from this analysis is that the routine use of subcutaneous or subaponeurotic drains during CS does not appear to confer any substantial benefit. However, no sub-analysis in obese women was performed.

In a prospective case–control study conducted in Egypt evaluating 118 women with a BMI >32 kg/m ² undergoing CS with a Pfannenstiel incision, no difference in wound dehiscence or haematoma formation was found between those who had subcutaneous drains and those who did not . In a retrospective US cohort of 194 patients with a BMI >50 kg/m ² undergoing CS, the use of subcutaneous drains was associated with an increased risk of wound complications (OR 2.3 95% CI 1.23–4.38) .

In a multicentre RCT in the USA, 280 women with >4 cm of subcutaneous thickness undergoing CS were randomised to subcutaneous layer closure alone or in combination with subcutaneous suction drainage. The incidence of composite wound morbidity (subcutaneous or fascial dehiscence, seroma, haematoma and abscess) was similar in both groups, as were individual wound complications and hospital readmission rates for this motive .

In conclusion, the existing evidence strongly suggests that the use of subcutaneous drainage during CS in obese women does not reduce the incidence of wound complications.

Closure of the skin

Skin closure in CS is usually performed with subcuticular sutures, interrupted sutures or non-absorbable staples. A systematic review identified eight RCTs evaluating these three alternatives for closure of the Pfannenstiel incision in the general CS population, and found similar incidences of wound complications with staples and subcuticular sutures, as well as similar pain and cosmetic results . Staple removal before the fourth post-operative day was associated with an increased risk of skin separation.

A recent RCT from Egypt compared the incidence of wound complications in 130 obese non-diabetic women, between subcuticular and interrupted mattress skin sutures, both using non-absorbable polypropylene . Subcuticular sutures took lesser time, and were associated with better cosmetic results but more pain. The incidence of wound infection was similar in both groups, but the study was clearly underpowered to evaluate this outcome.

In conclusion, the evidence on which to base the choice of method for skin closure in CS in obese women is limited, but there is little to suggest that it should be different from that of the general population.