Intraoperative Surgical Complications
Recognized intraoperative surgical complications include damage to adjacent organs, including bladder, urinary tract or bowel, as well as unintentional damage to the uterus or cervix. The occurrence of one or more of these complications is reported to be approximately 12%.[27,36]
Nielsen and Hokegard prospectively studied the incidence of surgical complications in 1319 women undergoing CS from 1978 to 1980. The overall complication rate was 11.6%, with a significant difference noted between elective and emergency procedures (4.2 and 18.9%, respectively). For women undergoing an emergency cesarean birth, a number of factors were associated with an increased risk of complications, including relationship of the presenting part to spines, labor prior to CS, prematurity, ruptured membranes prior to CS, previous surgery and skill level of the surgeon.
More recently, Bergholt and colleagues conducted a retrospective chart review of 929 cesarean births, noting the occurrence of laceration of the uterus, cervix, bladder, vagina or bowel, intraoperative blood loss of more than 1000 ml, blood transfusion, hysterectomy and uterine rupture. Overall, the chance of any surgical complication was 12.1%, significantly higher in the emergency CS group (14.5%) compared with the elective CS group (6.8%). Hysterectomy and bladder laceration were uncommon at 0.2 and 0.5%, respectively, and did not differ significantly between emergency and elective procedures. Vaginal lacerations (overall 1.2%) and cervical lacerations (overall 3.6%) accounted for the difference in complications between the emergency and elective procedures, with both outcomes being significantly more common during emergency surgical birth.
Villar et al. reported the results of a multicenter prospective study, comparing pregnancy outcomes associated with cesarean birth as part of the 2005 WHO survey on maternal and perinatal health. Data were collected on almost 100,000 births in 120 Latin American health facilities, and maternal and infant outcomes examined after adjusting for clinical, demographic and pregnancy characteristics. Hysterectomy was uncommon in the vaginal birth reference group (0.05%) but was significantly more common among women who experienced both elective, (odds ratio [OR]: 4.57; 95% CI: 2.84–7.37) and emergency cesarean birth (adjusted OR: 4.73; 95% CI: 2.79–8.02). Similar results were seen in the WHO maternal and perinatal health survey conducted in Asian regions.
Repeat Cesarean Birth
Sobande evaluated the risk of surgical complications in women with multiple repeat cesarean births (three or more procedures). A retrospective review of 371 women compared the incidence of surgical complications in women with three or more prior cesareans, compared with women who had experienced only one prior CS. Of the outcomes reported (bladder injury, bowel injury, cesarean hysterectomy, wound infection/dehiscence, blood transfusion, deep vein thrombosis [DVT] and uterine rupture), bladder injury, occurring in 1.7% of women having three or more prior cesareans, was significantly higher when compared with women with one prior CS (0%). There were no significant differences in risk of other adverse outcomes identified. While there are limitations with a retrospective study design, this study clearly describes the complications of multiple repeat CS in a population of women more likely to undergo multiple cesarean births against a high background rate of grand multiparity.
Silver et al. described maternal morbidity in over 30,000 women experiencing CS without labor, from 19 medical centers. Primary outcomes included: placenta accreta; placenta previa; bladder; bowel or ureteral injury; hysterectomy; blood products; admission to the intensive care unit (ICU); ventilator support; deep venous thrombosis; pulmonary embolism; postpartum endometritis; wound infection; wound dehiscence; ileus; and maternal death. A statistically significant trend towards increasing risk of outcomes of morbidity with increasing number of previous CS births was observed, although direct statistical comparisons by number of prior cesarean births was only made for a small number of outcomes. Placenta accreta was reported for 0.24% of women experiencing their first CS birth, compared with 0.31, 0.57, 2.13, 2.33 and 6.74% of women experiencing their second, third, fourth, fifth and sixth or more CS births, respectively. Similarly, hysterectomy was reported for 0.65% of first CS deliveries compared with 0.42, 0.90, 2.41, 3.49 and 8.99% of second, third, fourth, fifth and sixth or more CS births, respectively.
Late Surgical Complications
Fawzy and Zalata recently reported the incidence of late surgical intervention following cesarean birth in a cohort of 5981 women in Egypt. Surgical intervention was required in 24 women (0.4%) 6 weeks postpartum and beyond, with ten women requiring surgery for skin lesions, and 12 for abdominal or pelvic masses (the pathology results indicating inflammatory reaction in most cases).
Blood Loss & Transfusion
In Bergholt's retrospective review of almost 1000 cesareans, estimated blood loss of greater than 1000 ml was recorded in 9.2% of cesarean births, with 1% of women requiring a blood transfusion. These rates were similar for both elective and emergency births. In the large WHO studies in Asia and Latin America, blood transfusion was reported in less than 1% of women.[29,30] However, it was significantly more common following both elective (adjusted OR: 1.75; 95% CI: 1.33–2.30) and emergency cesarean (adjusted OR: 1.39; 95% CI: 1.10–1.76) when compared with vaginal birth.
Infectious complications following cesarean birth include endometritis, urinary tract infection, wound infection and more significant risks such as sepsis and bacteremia. Some authors also report surrogate markers of infection such as fever in the immediate postpartum period and additional antibiotic use after birth.
The Cochrane systematic review assessing the effects of antibiotic prophylaxis in women undergoing cesarean birth describes the occurrence of infectious complications in over 80 RCTs involving 11,000 women. The review reports a consistently large reduction in all types of infectious complications with the provision of prophylactic antibiotics for endometritis (RR: 0.39; 95% CI: 0.31–0.43), and for wound infection (RR: 0.41; 95% CI: 0.29–0.43). Febrile morbidity (defined as any significant fever after birth) was reported in approximately 30% of women undergoing CS. Prophylactic antibiotics at the time of surgery reduced this risk by 50% to 15%. Regardless of the provision of treatment, febrile morbidity was documented to be approximately twice as common following emergency procedures, compared with elective CS. Following antibiotic treatment, wound infection was reported in 6% of women, endometritis in 6% and urinary tract infection in 6%. It should be noted that most trials reported outcomes to the time of hospital discharge, and are therefore more likely to underestimate the incidence of these complications. Serious infectious morbidity (defined as bacteremia, septic shock, septic thrombophlebitis, necrotizing fascitis or death attributed to infection) was reported following 1–2% of cesarean births. Prophylactic antibiotic therapy at the time of the primary procedure has also been reported to reduce the incidence of such complications (RR: 0.44; 95% CI: 0.29–0.68). Although most studies have administered antibiotics after cord clamping to avoid the small theoretical risk of neonatal antibiotic exposure and anaphylaxis, these outcomes, are poorly reported in the randomized studies examining the effects of antibiotic prophylaxis. For optimal maternal outcomes antibiotics should be administered at the time of skin incision, or preoperatively, as this practice is associated with lower rates of endometritis (RR: 0.47; 95% CI: 0.26–0.85) and total infectious morbidity (RR: 0.50; 95% CI: 0.33–0.78), as reported in a recent systematic review specifically assessing the timing of antibiotic prophylaxis. In recognition of the benefits of prophylactic antibiotics, clinical practice guidelines currently recommend their administration to all women undergoing CS.
Where infectious morbidity is measured by the surrogate marker of antibiotic treatment after birth, women who birth by elective CS are four-times more likely than those who experience vaginal birth to require antibiotic treatment (62 vs 24%; OR: 4.24; 95% CI: 2.78–6.46). This increases to a fivefold increased risk among women who require emergency CS (70 vs 24%; adjusted OR: 5.53; 95% CI: 3.77–8.10).
Thromboembolic disease is a significant contributor to maternal mortality and morbidity, with pulmonary embolism the leading cause of direct maternal death in the UK (1.56 out of 100,000 maternities) and the second most common cause of all maternal death (direct and indirect), accounting for 11% of reported deaths. The highest risk period for venous thromboembolic disease and pulmonary embolism in particular is the postpartum period, as the well-documented prothrombotic physiological changes of pregnancy are greatest at this time and continue until 6 weeks postpartum.
Cesarean birth is a recognized risk factor for thromboembolic disease, increasing the risk by two- to four-fold compared with vaginal birth.[32,44,45] In addition to CS, other recognized factors associated with risk of venous thromboembolism include protracted labor, immobility, infection, hemorrhage and blood transfusion. All of these factors may occur independently or in association with cesarean birth. It is reported that over two-thirds of women diagnosed with venous thromboembolism in pregnancy or the peurperium have at least one risk factor as identified previously. Evidence-based guidelines have been developed that recommend thromboprophylaxis based upon a thorough assessment of pre-existing, obstetric, transient and potentially reversible risk factors.
Severe Acute Maternal Morbidity & Mortality
Significant maternal morbidity is often used as a proxy for maternal mortality, as maternal mortality rates, from any cause, are low in developed countries. Severe acute maternal morbidity (SAMM) is often described as a 'near miss' event and defined as "a very ill pregnant or recently delivered woman who would have died had it not been but luck and good quality care was on her side". SAMM is reported using disease-specific criteria (eclampsia or massive obstetric hemorrhage), organ-system-based criteria (respiratory, liver or renal insufficiency) or management-based criteria (hysterectomy, arterial embolization or ICU admission).
Zwart and colleagues conducted a large nation-wide prospective population-based cohort study in The Netherlands, examining the incidence of and risk factors for SAMM, including data on 371,000 pregnancies. In this study, SAMM was defined as ICU admission, uterine rupture, eclampsia or hemolysis, elevated liver enzymes and low platelets (HELLP) syndrome or massive obstetric hemorrhage (bleeding requiring embolization, hysterectomy or >4-unit blood transfusion). The overall incidence of SAMM was 7.1 per 1000 births and, regardless of the mode of birth, advanced maternal age, high BMI and nulliparity were identified as significant risk factors. Any type of cesarean birth was associated with a five-times increased risk (RR: 5.2; 95% CI: 4.8–5.6) of SAMM, even in the absence of labor (RR: 4.6; 95% CI: 4.2–5.0).
Other large population-based cohort studies have demonstrated similarly increased risks of SAMM for cesarean birth when compared with vaginal birth. A large Finnish register-based retrospective cohort study of 110,000 births over 5 years linked birth register and discharge data to determine the incidence of SAMM. In this study, SAMM was defined as the occurrence of DVT, amniotic fluid embolism, major infection, severe hemorrhage, operative intervention after birth, uterine rupture, uterine inversion or bowel obstruction. When compared with spontaneous vaginal birth, the authors report a greater than 2.5-times (RR: 2.7; 95% CI: 2.2–3.4) increased risk of severe maternal morbidity following elective CS, increasing to six-times (RR: 6.1; 95% CI: 5.3–7.0) following emergency cesarean.
Similarly, in the large WHO study of pregnancy outcomes in Latin American countries, women who underwent cesarean birth had an increased risk of both severe maternal morbidity (admission to ICU, hysterectomy, blood transfusion or hospital stay greater than 7 days) and mortality compared with women who experienced vaginal birth. This effect was evident for both emergency intrapartum (OR: 2.0; 95% CI: 1.6–2.5) and elective (OR: 2.3; 95% CI: 1.7–3.1) cesarean birth. While CS was associated with an increased risk of maternal death (OR: 3.38; 95% CI: 1.07–10.65 for elective CS and OR: 5.28; 95% CI: 2.05–13.62 for emergency CS), the absolute risk of death was low (0.04% for elective CS and 0.06% for emergency CS). Overall, 5.5% of women who experienced elective cesarean birth and 4.0% of those with an intrapartum CS were affected by severe morbidity or mortality, compared with 1.8% of women achieving vaginal birth.
Vadnais described the risk of maternal mortality associated with cesarean birth in a systematic review that included any type of study evaluating maternal mortality relating to mode of birth. The review identified five retrospective reviews, one RCT, one retrospective cohort study, one case–control study and one meta-analysis. Owing to the heterogeneous nature of the study designs, results were not combined in a meta-analysis. In particular, the definition of maternal death varied between studies, ranging from death within 6 weeks to death within 12 months of birth. The RR of direct obstetrical death with cesarean birth, for any reason, compared with vaginal birth, ranged from three to 13. However, the only studies reporting a significant difference between mode of birth were those with weaker methodology. Of note, the only RCT that reported on maternal death did not identify a significant difference between planned vaginal birth and planned CS, although none of the included studies had a sufficiently large sample size to detect such differences.
Expert Rev of Obstet Gynecol. 2011;6(2):205-215. © 2011 Expert Reviews Ltd.
Cite this: Short- and Long-term Outcomes after Cesarean Section - Medscape - Mar 01, 2011.