INTRODUCTION — Cesarean birth (also called cesarean section) is one of the most common major surgical procedures performed in an operating room in the United States. Cesarean births comprise almost one-third of births in the United States [1]. It is also a common procedure in many countries worldwide, and the rate is generally rising [2]. Concerns about the rising rate have prompted medical organizations to suggest potential interventions to reduce the rate of unnecessary procedures, such as education, standardization, better childbirth preparation, second opinion before/peer review after a cesarean, broader midwifery-led care, more trials of labor after a cesarean, continuous labor support, multifaceted toolkits, changes in current financial incentives/disincentives, and process measures with rapid feedback [3-6]. There is some evidence that implementation of a multifaceted approach to support vaginal birth can be effective in reducing cesarean births in nulliparous, term, singleton, vertex pregnancies [7].

This topic will review preoperative planning and patient preparation for cesarean birth. Surgical technique, postoperative issues, repeat cesarean birth, cesarean birth on maternal request, and trial of labor after cesarean birth are discussed separately:

●(See "Cesarean birth: Surgical technique and wound care".)

●(See "Cesarean birth: Postoperative issues".)

●(See "Repeat cesarean birth".)

●(See "Cesarean birth on maternal request".)

●(See "Choosing the route of delivery after cesarean birth".)

The Enhanced Recovery After Surgery (ERAS) Society has published guidelines for perioperative care of patients undergoing cesarean birth, the ERAS Cesarean Delivery Guidelines, which cover the time from decision to operate (starting with the 30 to 60 minutes before skin incision) to hospital discharge [8-10]. The American College of Obstetricians and Gynecologists has published a guideline for enhanced recovery after surgery [11]. Other organizations and many hospitals have also created such guidelines/pathways [12].

INDICATIONS — Cesarean birth is performed when the clinician and/or patient believe that abdominal delivery is likely to provide a better maternal and/or fetal outcome than vaginal delivery. Thus, indications for cesarean birth fall into two general categories:

●Medically/obstetrically indicated, or

●On maternal request

Approximately 70 percent of cesarean births in the United States are primary (first) cesareans. The three most common indications for primary cesarean birth in the United States account for almost 80 percent of these births [13]:

●Failure to progress during labor (35 percent)

●Nonreassuring fetal status (24 percent)

●Fetal malpresentation (19 percent)

Additionally, less common indications for primary cesarean birth include, but are not limited to:

●Abnormal placentation (eg, placenta previa, vasa previa, placenta accreta)

●Maternal infection with significant risk of perinatal transmission during vaginal birth

●Some fetal bleeding diatheses

●Funic presentation or cord prolapse

●Suspected macrosomia (typically 5000 grams in women without diabetes, 4500 grams in women with diabetes)

●Mechanical obstruction to vaginal birth (eg, large fibroid, severely displaced pelvic fracture, severe fetal hydrocephalus)

●Uterine rupture

●Prior uterine surgery that entered the endometrial cavity, such as myomectomy

Although infrequent, cesarean birth is also indicated in women who are at increased risk for complications/injury from cervical dilation, descent and expulsion of the fetus, or episiotomy. Some examples include women with invasive cervical cancer, active perianal inflammatory bowel disease, or history of repair of a rectovaginal fistula or pelvic organ prolapse. (See "Cervical cancer in pregnancy" and "Fertility, pregnancy, and nursing in inflammatory bowel disease" and "Effect of pregnancy and childbirth on urinary incontinence and pelvic organ prolapse" and "Fecal and anal incontinence associated with pregnancy and childbirth: Counseling, evaluation, and management".)

Cesarean birth on maternal request is uncommon, and discussed separately. (See "Cesarean birth on maternal request".)

Cesarean birth is not routinely indicated for low birth weight (see "Delivery of the low birth weight singleton fetus") and most congenital anomalies. (Refer to topic reviews on individual anomalies.)

CONTRAINDICATIONS — There are no absolute contraindications to cesarean birth. In contrast to other types of surgery, the risks and benefits of the procedure are considered as they apply to two patients (mother and fetus). However, many pregnant women have a low tolerance for accepting any fetal risk from vaginal birth, irrespective of the maternal risks associated with cesarean birth [14,15].

PREOPERATIVE PLANNING

Checklists — Checklists can be helpful in preoperative planning and are available from various organizations, such as the American College of Obstetricians and Gynecologists and Agency for Healthcare Research and Quality (AHRQ).

Postpartum contraception — Postpartum contraception plans should be discussed. (See "Postpartum contraception: Counseling and methods".)

For women who are certain that they desire permanent contraception, the procedure can be performed at the time of cesarean birth. (See "Overview of female permanent contraception" and "Postpartum permanent contraception: Procedures", section on 'Following cesarean birth'.)

Scheduling

Medically or obstetrically indicated procedures — Medically/obstetrically indicated cesarean births are scheduled when clinically indicated. Indications for administration of a course of antenatal corticosteroids before delivery, if time permits, are reviewed separately. (See "Antenatal corticosteroid therapy for reduction of neonatal respiratory morbidity and mortality from preterm delivery", section on 'Candidates for a first ACS course by gestational age'.)

When a primary cesarean birth is indicated for maternal or fetal reasons, but preterm birth is not indicated, there is consensus that planned term cesarean birth should be scheduled in the 39^th or 40^th week of gestation [16-18]. We caution against performing early term (in the 37^th or 38^th week of gestation) cesareans when the medical/obstetric indication for delivery is "soft," such as a history of fetal, maternal, or obstetric complication in a previous pregnancy that has not recurred.

In suboptimally dated pregnancies, scheduling should be based on the best clinical estimate of gestational age [19]. Performing an amniocentesis for assessment of fetal lung maturity is not recommended as a component of this decision and is rarely, if ever, clinically available.

This approach is based on data from large, observational studies and randomized trials that consistently show that neonatal respiratory morbidity and/or composite neonatal morbidity is higher after scheduled cesarean birth than after vaginal delivery and decreases as gestational age increases from 37 to 40 weeks [20-28]. An example of the magnitude of these risks was provided by a trial that evaluated adverse neonatal outcomes according to completed week of gestation in over 13,000 elective cesareans performed before the onset of labor [29]. Delivery <39 weeks of gestation was associated with a statistically higher risk of respiratory and other adverse neonatal outcomes compared with delivery ≥39 weeks of gestation:

●Rates of respiratory distress syndrome/transient tachypnea by gestational age were 37 weeks (8.2 percent), 38 weeks (5.5 percent), 39 weeks (3.4 percent), 40 weeks (3 percent), and 41 weeks (5.2 percent)

●Rates of any adverse outcome/death by gestational were 37 weeks (15.3 percent), 38 weeks (11 percent), 39 weeks (8 percent), 40 weeks (7.3 percent), and 41 weeks (11.3 percent)

Scheduled/planned repeat cesarean birth — Timing of scheduled/planned repeat cesarean birth is based on the type of previous hysterotomy incision and is reviewed separately. (See "Repeat cesarean birth", section on 'Timing'.)

Cesarean birth on maternal request — Cesarean birth on maternal request is scheduled for the 39^th or 40^th week of gestation. (See "Cesarean birth on maternal request".)

Natural, gentle, or family-centered cesarean — The natural, gentle, or family-centered cesarean birth approach was developed to improve the birth experience of women having uncomplicated cesarean births. It attempts to replicate features of vaginal birth as much as possible to make cesarean surgery more family friendly. Components of this approach may include [30,31]:

●Playing background music of the mother's and father's choice during delivery and dimming lights, when safely possible. Reduction of extraneous noise.

●Using clear drapes or positioning the drapes to allow the mother (and father) to watch the birth.

●Avoiding maternal sedation.

●Allowing the baby to deliver by a combination of uterine expulsion and active physician assistance to mimic expulsion from the vagina.

●Freeing the mother's dominant hand/arm and chest/breasts from lines and monitors, when possible, so she can hold and nurse her infant.

●Promoting skin-to-skin contact and nursing immediately after birth.

We perform family-centered cesarean whenever feasible (ie, routinely unless an emergency cesarean needs to be performed). Patients become an active part of the cesarean birth by directly observing the birth and by cutting the umbilical cord. In a randomized trial, family-centered cesarean was safe for both mother and infant and led to a better birth experience, higher rate of breastfeeding, and improved early mother-infant interaction [32].

Intrapartum cesarean — Intrapartum cesarean births are sometimes classified by degree of urgency; for example: (1) an immediate threat to life of the mother or fetus is present, (2) signs of maternal or fetal compromise are present but are not immediately life threatening, or (3) delivery is needed, but there is no evidence of maternal or fetal compromise. Compared with scheduled cesarean birth, intrapartum cesarean is associated with increased risks of postpartum hemorrhage, anesthetic complications from rapid administration of general anesthesia, and accidental injury to the fetus or abdominopelvic organs.

Although, historically, facilities providing obstetric services were asked to be capable of beginning an intrapartum cesarean birth within 30 minutes of the decision to perform the operation, this criterion was based upon the practical constraints most rural hospitals faced in assembling the appropriate team of nurses, anesthetists, and surgeons. This threshold was not evidence-based, universally achievable, or ideal from the perspective of decreasing perinatal mortality and morbidity [33-42]. The ability to begin an intrapartum cesarean birth within 30 minutes of the decision to operate is a reasonable benchmark for monitoring the quality of labor and delivery units but not a requirement that all cesarean births be performed within 30 minutes of the decision. In human and animal studies, sudden complete anoxia, such as occurs with a total abruption or complete cord occlusion, probably necessitates delivery within five minutes to avoid fetal hypoxic injury [43-45], although intact survivors have been reported after longer durations of severe hypoxia. Most pregnancies with less severe fetal or maternal compromise or partial or complete recovery of nonreassuring fetal heart rate tracings will have good outcomes despite longer intervals before initiating surgery [42].

PREPROCEDURE MATERNAL PREPARATIONS

Skin self-cleansing — We do not ask patients to use any particular product to cleanse their skin before surgery. Meta-analyses of randomized trials of preoperative bathing or showering with chlorhexidine or other products before a variety of surgical procedures have not found a clear reduction in surgical site infection rates [46-49].

Skin preparation in the operating room is discussed below. (See 'Skin preparation' below.)

Anesthesia consultation — As with any surgical procedure, women undergoing cesarean birth should have a preoperative consultation with the anesthesia team. Those whose procedure-related risks are above baseline should have a preadmission consultation, if possible. Characteristics that place the patient at increased risk include, but are not limited to, those listed in the table (table 1).

The choice of regional or general anesthesia is influenced by factors such as the urgency of the procedure, maternal status, and physician and patient preference. Issues related to anesthesia for cesarean birth, including preanesthetic medications (eg, antacids, histamine H2 receptor antagonists) and oral intake, are discussed in detail separately. (See "Anesthesia for cesarean delivery".)

Laboratory testing — A baseline hemoglobin or hematocrit measurement is recommended for patients who are undergoing major surgery, such as cesarean birth, that is expected to result in significant blood loss. A normal value obtained within one month of surgery probably does not need to be repeated preoperatively in uncomplicated pregnancies. (See "Preoperative medical evaluation of the healthy adult patient".)

Pregnant women generally have a blood type and antibody screen performed as part of routine prenatal care. While a repeat type and screen preoperatively probably could be safely omitted in women at low risk of severe bleeding during surgery and who do not have a known red blood cell antibody [50-54], we obtain this testing routinely on every woman preoperatively, either as outpatient within three days of planned delivery or on the morning of admission. Alternatively, the surgeon may consider a "hold clot" order in low-risk patients: Blood is drawn and held, but no tests are performed unless clinically indicated.

Approximately 2 percent of women undergoing primary cesarean birth receive a blood transfusion [52]. The risk is <1 percent in women at low risk of bleeding. Risk factors for requiring transfusion include placental abnormalities (eg, previa, placenta accreta spectrum, or placental abruption), eclampsia or HELLP syndrome (ie, Hemolysis, Elevated Liver function tests, Low Platelets), preoperative hematocrit <25 percent, use of general anesthesia, and a history of ≥5 cesarean births.

Antibiotic prophylaxis

Regimen — For all women undergoing cesarean birth, we administer a single dose of cefazolin in the 60 minutes before making the skin incision and add a single dose of azithromycin 500 mg intravenously for those in labor or with ruptured membranes.

Our cefazolin dosing is as follows:

●Women <120 kg – 2 g intravenously

●Women ≥120 kg – 3 g intravenously

We also perform antiseptic abdominal and vaginal preparations. (See 'Skin preparation' below and 'Vaginal preparation' below.)

The American College of Obstetricians and Gynecologists (ACOG) also recommends a single dose of a first-generation cephalosporin; however, their dosing regimen is lower (cefazolin 1 g IV for women <80 kg, 2 g for women ≥80 kg, and 3 g for women ≥120 kg) [55].

Evidence — In the absence of antimicrobial prophylaxis, women undergoing cesarean birth have a 5- to 20-fold greater risk for infection compared with women who give birth vaginally [56]. The benefit of antibiotic prophylaxis before cesarean birth was illustrated in a systematic review of randomized trials that compared maternal outcomes "with" versus "without" use of prophylactic antibiotics and found that antibiotic prophylaxis reduced the risk of endometritis by approximately 60 percent in both antepartum and intrapartum cesarean births (95 trials, n >15,000 women) [56]. The risks of wound infection, urinary tract infection, and serious maternal infectious complications were also reduced. In a smaller systematic review that evaluated neonatal outcomes (12 trials, n >5000 women), maternal antibiotic prophylaxis did not significantly impact the risk of neonatal sepsis (risk ratio [RR] 0.76, 95% CI 0.51-1.13) or neonatal infection with antimicrobial-resistant bacteria (RR 0.70, 95% CI 0.32-4.14), but more data are needed to confirm these findings [57].

Although the relative risk reduction in maternal infection is statistically significant and similar for both antepartum and intrapartum procedures, the absolute risk of maternal infection is quite low in antepartum cases: In a large observational study, postpartum endometritis occurred in 2 percent of women with antibiotic prophylaxis versus 2.6 percent without antibiotic prophylaxis; wound infection occurred in 0.52 percent of women with antibiotic prophylaxis versus 0.96 percent without antibiotic prophylaxis [58]. Thus, 1000 women undergoing antepartum cesarean birth would receive antibiotics to prevent 6 cases of endometritis and 4.4 cases of abdominal wound infection. The low risk of maternal infection in these cases and uncertainty about long-term effects in offspring have prompted a call for more research on potential long-term risks of exposure to antibiotic prophylaxis and strategies for risk stratification to identify the best candidates for antibiotic prophylaxis [59]. Until these data are available, we administer antibiotics before all cesarean births, in accordance with ACOG guidelines [55].

Antimicrobial therapy should be administered within 60 minutes before making the skin incision to ensure adequate drug tissue levels [55]. This recommendation is supported by a 2014 meta-analysis of randomized trials that compared infection rates in women assigned to a single pre-incision dose of antibiotic prophylaxis versus those assigned to administration after cord clamping [57]. Pre-incision prophylaxis was significantly more effective than delayed administration for prevention of endometritis (RR 0.54, 95% CI 0.36-0.79) and was not associated with an increase in proven neonatal sepsis, sepsis work-ups, or admission to the neonatal intensive care unit, although the trials had limited power to detect adverse neonatal effects. (See "Antimicrobial prophylaxis for prevention of surgical site infection in adults", section on 'Timing'.)

Comparative trials do not provide strong evidence on which to base a recommendation for the optimal drug and dose. Based on expert opinion from infectious disease experts, we administer cefazolin, with dosing based on weight [60]. The higher dose for women who are obese is based on pharmacokinetic data rather than surgical site infection rates, and these data have been inconsistent [61-65]. Cefazolin has a longer half-life than ampicillin (1.8 versus 0.7 to 1.5 hours in adults with normal renal function [66]), which is an advantage in long surgeries. In a 2021 systematic review of randomized trials, first- and second-generation cephalosporins (eg, cefazolin, cefoxitin) and broad-spectrum penicillins plus betalactamase inhibitors (eg, amoxicillin plus clavulanic acid, ampicillin plus sulbactam) appeared to be similarly effective for preventing postoperative maternal infection (endometritis, wound infection) after cesarean birth; use of adjunctive azithromycin to target Ureaplasma and Mycoplasma species was not evaluated [67]. Other systematic reviews of randomized trials have noted that a single dose of antibiotics is as effective as multiple doses [68,69].

Additional data from randomized trials support use of extended-spectrum antibiotic combinations (eg, cefazolin plus azithromycin, cefazolin plus metronidazole) for women at high risk of post-cesarean infection [70]. In a placebo-controlled multicenter randomized trial including over 2000 women, administration of azithromycin 500 mg intravenously before skin incision in addition to preoperative cefazolin resulted in a 50 percent reduction in the composite outcome of endometritis, wound infection, or other infection (endometritis 3.8 versus 6.1 percent, wound infection 2.4 versus 6.6 percent; composite RR 0.51, 95% CI 0.38-0.68), without impacting the frequency of adverse neonatal outcomes [71]. The authors also found that adjunctive azithromycin prophylaxis was cost-effective [72]. Of note, only women who had a cesarean birth during labor or at least four hours after rupture of membranes were included, so these data do not apply to other cesarean births (eg, antepartum cesarean births with intact membranes). Specific tests for Ureaplasma or Mycoplasma species were not routinely performed, thus it is not known whether coverage against Ureaplasma and Mycoplasma species provided by the extended antibiotic regimen accounted for the reduction in postoperative infection.

Ideally, azithromycin is infused 60 minutes before making the skin incision, but this may not be possible intrapartum. In this trial, the drug appeared to be effective regardless of timing of administration; 83 percent of patients received azithromycin 0 to 60 minutes before the skin incision, 5 percent received it >60 minutes before the incision, and 12 percent received it after the incision was made [71].

This trial provides the best evidence to date of the benefits of an extended-spectrum regimen and has led us to begin using preoperative cefazolin PLUS azithromycin for intrapartum cesareans and cesareans in women with ruptured membranes. Some clinicians also use this combination in other women at high risk for postoperative surgical site infection. However, we believe a strong recommendation in favor of routine or broader use of extended-spectrum prophylaxis is unwarranted at this time, given the high prevalence of obesity in at least one of the trial populations (>70 percent [71]), the lack of comparative data on the efficacy of high-dose (3 g) cefazolin for prevention of surgical site infection in obese women undergoing cesarean birth, the lack of microbial data in these trials, concern about inducing resistance to azithromycin, and concern about possible effects on establishment of the indigenous intestinal microbiome [73-76]. ACOG states that azithromycin may be considered in unplanned cesareans [55]. Observational data do not support a benefit for routine use in all cesarean births [77].

Traditionally, prophylaxis has not been continued postpartum because studies in general surgical populations showed no benefit from postoperative antimicrobial prophylaxis. However, one trial in obese women undergoing cesarean birth reported a benefit of antibiotic prophylaxis for 48 hours following cesarean birth when given in addition to preoperative prophylaxis. (See "Cesarean birth: Patients with obesity", section on 'Antibiotic prophylaxis'.)

Special populations

Women with penicillin allergy — These women fall into two groups: those with previous serious reactions and those at low risk for a serious reaction.

●For women with a history of serious forms of penicillin allergy undergoing antepartum cesarean birth with intact membranes, we suggest combination therapy with a single dose of [55,60]:

•Clindamycin 900 mg intravenously PLUS

•Gentamicin 5 mg/kg intravenously

If cesarean is performed intrapartum or after rupture of membranes we add azithromycin 500 mg intravenously.

Serious forms of penicillin allergy include immediate reactions (ie, anaphylactic) (table 2), as well several types of delayed reactions (Stevens-Johnson syndrome [SJS], toxic epidermal necrolysis [TEN], drug rash eosinophilia systemic symptoms [DRESS], drug-induced liver or other organ injury, and drug-induced cytopenias).

When gentamicin is used for prophylaxis in combination with a parenteral antimicrobial with activity against anaerobic agents, we advise 4.5 to 5 mg/kg of gentamicin as a single dose as many studies support the safety and efficacy of this dose when used as a single dose for prophylaxis in patients without renal insufficiency. In addition, a trial of antibiotic prophylaxis in colorectal surgery reported that this dose may be more effective than multiple standard doses of 1.5 mg/kg during prolonged surgeries [78]. However, cesarean birth typically takes less than an hour; thus, a lower dose of gentamicin may be adequate; there are no comparative dosing trials in this population. Single daily dose gentamicin dosing does not appear be associated with more neonatal nephrotoxicity or auditory toxicity than multiple daily doses [79].

●For women at low risk of a serious immediate allergic reaction, cefazolin can be administered, as described above (see 'Regimen' above). The risk of a penicillin-allergic patient reacting to a cephalosporin may be assessed based upon the results of penicillin skin testing (if available), the clinical features of the penicillin reaction, and the time elapsed since the last reaction to penicillin (algorithm 1). If cesarean is performed intrapartum or after rupture of membranes we add azithromycin 500 mg intravenously. (See "Allergy evaluation for immediate penicillin allergy: Skin test-based diagnostic strategies and cross-reactivity with other beta-lactam antibiotics" and "Penicillin allergy: Immediate reactions".)

Woman already on antibiotics — There are no randomized trials assessing efficacy of antibiotic regimens in these clinical scenarios.

●Woman receiving GBS prophylaxis – When cesarean birth is performed in a woman in labor or with ruptured membranes receiving penicillin G for neonatal Group B Streptococcus (GBS) prophylaxis, we do not add a cephalosporin or switch to ampicillin for surgical prophylaxis, but we add a dose of azithromycin. Alternatively, some clinicians add a single dose of a narrow-spectrum antibiotic (eg, cefazolin) as well as a dose of azithromycin to the penicillin G protocol for GBS prophylaxis.

●Women with chorioamnionitis – Ampicillin plus gentamicin is a common regimen for treatment of chorioamnionitis. For women already on this regimen, we also administer either one dose of clindamycin 900 mg or metronidazole 500 mg before beginning the cesarean. We do not administer azithromycin to these patients.

Postpartum, it is reasonable to either continue ampicillin plus gentamicin or switch to ampicillin-sulbactam until the patient is afebrile for at least 24 hours. Bacteroides resistance to clindamycin is increasing, thus, in areas of high resistance, ampicillin-sulbactam is preferable. (See "Intraamniotic infection (clinical chorioamnionitis)", section on 'Postpartum treatment'.)

Prolonged surgery or excessive blood loss — Antibiotic levels fall over time and with blood loss. Although redosing is the standard of care in other surgeries, there are no specific data for cesarean birth [80]. A second dose of cefazolin is reasonable in patients with postpartum hemorrhage >1500 mL [55]. A second dose of cefazolin is also appropriate for the rare complicated cesarean birth that extends beyond four hours since the half-lives of cefazolin and azithromycin are approximately 1.8 and 68 hours, respectively.

A joint guideline of the American Society of Health-System Pharmacists, the Infectious Diseases Society of America, the Surgical Infection Society, and the Society for Healthcare Epidemiology of America suggests consideration of additional intraoperative doses in patients with excessive blood loss (>1500 mL) or extended surgery (duration exceeding two half-lives of the drug) [60,81].

Nasal colonization with methicillin-resistant S. aureus — Routine screening for MRSA is not indicated. Management of women known to be colonized (addition of a single dose of vancomycin) is discussed separately. (See "Antimicrobial prophylaxis for prevention of surgical site infection in adults", section on 'Role of vancomycin'.)

Thromboembolism prophylaxis

Risk of venous thromboembolism and pulmonary embolism — A study using claims data from 1.7 million pregnancies reported that the frequency of a thrombotic event (ischemic stroke, acute myocardial infarction, venous thromboembolism) was 246 per 100,000 cesarean births during the first six postpartum weeks [82]. This rate was 20-fold higher than the rate one year later and significantly higher than the rate after vaginal delivery (165 per 100,000). Compared with vaginal delivery, a meta-analysis found that the odds of VTE (deep vein thrombosis and/or pulmonary embolism) following elective and emergency cesarean birth were OR 2.3 and 3.6, respectively, and the overall pooled incidence of VTE was 260 per 100,000 cesareans [83]. A large prospective study reported even lower VTE rates: 63/100,000 planned repeat cesareans and 84/100,000 emergency cesareans [84]. Although pulmonary embolism is a common cause of maternal mortality [85] and over 80 percent of fatal puerperal pulmonary embolism occurs after cesarean birth [86], these data suggest that the absolute level of risk for clinically important events is modest and similar to that seen in very low-risk surgical patients, in whom routine thromboprophylaxis is not recommended (other than early ambulation). (See "Prevention of venous thromboembolic disease in adult nonorthopedic surgical patients", section on 'Very low thrombosis risk: Early ambulation'.)

Our approach — The value of thromboprophylaxis for cesarean birth has not been studied in adequately powered, randomized trials that have assessed and quantified both benefits (prevention of venous thrombosis and/or pulmonary embolism) and harms (wound or bleeding complications, including unplanned surgical procedures and blood transfusions) [87-89]. International guidelines for thromboprophylaxis after cesarean differ markedly in selection of patients for this therapy because both the optimal threshold for initiating pharmacologic thromboprophylaxis and optimal duration of therapy are unclear [90]. Furthermore, no easy-to-use, validated tool is available for accurately determining absolute risk of postpartum VTE in an individual patient, although pilot studies of such tools have been reported [91,92]. Clinical validation is difficult given the relatively low incidence of VTE.

This is our approach:

●Low-risk women – We agree with the ACOG recommendation to [93]:

•Place a pneumatic compression device on all patients not already receiving pharmacologic thromboprophylaxis before cesarean birth

•Encourage early ambulation after cesarean birth

We continue pneumatic compression until the patient is fully ambulatory [94]. Pneumatic compression devices may be removed while the patient is ambulating but should be put back on when she returns to a seated or supine position. Observational studies of pregnant women suggest that pneumatic compression devices, as well as graduated compression stockings, are safe and effective [95,96].

●High-risk women – Consistent with ACOG recommendations [93]:

•We use both mechanical and pharmacologic thromboprophylaxis in women at high risk of VTE undergoing cesarean birth

•We encourage early ambulation after cesarean birth, as soon as eight hours postoperatively

Criteria for selecting women at high risk are challenging as high-quality data are not available [97]. We consider any of the following reasonable criteria for mechanical plus pharmacologic prophylaxis:

•Previous VTE.

•Any thrombophilia (inherited or acquired).

•Body mass index (BMI) >35 kg/m².

•≥2 less prominent risk factors for VTE – Numerous less prominent risk factors for VTE are described in the literature (eg, postpartum hemorrhage or infection, medical factors or pregnancy complications such as obesity, hypertension, autoimmune disease, heart disease, sickle cell disease, multiple gestation, preeclampsia); ACCP and RCOG risk factors are described below [98-109] (see 'ACCP recommendations' below and 'RCOG recommendations' below). The type and number of less prominent risk factors that meet the threshold for administering pharmacologic prophylaxis is decided on a case-by-case basis.

●Timing of pharmacologic therapy – Pharmacologic prophylaxis is begun 6 to 12 hours postoperatively, after concerns about hemorrhage have decreased, and is continued until the woman is fully ambulating, except for women with significant risk factors for postpartum VTE (eg, prior VTE, no prior VTE but high risk thrombophilia): These women should receive six weeks of thromboprophylaxis, and, depending on their medical history, they may require an indefinite period of anticoagulation. (See "Use of anticoagulants during pregnancy and postpartum", section on 'Duration of postpartum anticoagulation' and "Selecting adult patients with lower extremity deep venous thrombosis and pulmonary embolism for indefinite anticoagulation" and "Antiphospholipid syndrome: Pregnancy implications and management in pregnant women" and "Inherited thrombophilias in pregnancy".)

The Society for Obstetric Anesthesia and Perinatology suggests delaying initiation of therapeutic anticoagulation with low-molecular-weight heparin for at least 24 hours after initiation of neuraxial blockade and 4 hours after catheter removal, and using intravenous heparin if therapeutic anticoagulation is desired sooner after delivery [110] (see "Neuraxial anesthesia/analgesia techniques in the patient receiving anticoagulant or antiplatelet medication"). There are no data from randomized trials to support or refute these approaches.

Pneumatic compression devices should be left in place until pharmacologic prophylaxis has been started. We generally continue the device until the patient is discharged as it may offer additive benefit to surgical patients on heparin. (See "Prevention of venous thromboembolic disease in adult nonorthopedic surgical patients".)

●Heparin dosing – Unfractionated or low molecular weight heparin can be used.

•For women with BMI <40 kg/m², options include:

-Enoxaparin 40 mg subcutaneous injection daily (this is our preference), or

-Unfractionated heparin 5000 units subcutaneous injection every 12 hours

•For women with BMI ≥40 kg/m²:

-We prefer weight-based enoxaparin dosing rather than fixed dosing [111-113]: Begin enoxaparin 0.5 mg/kg subcutaneous injection every 12 hours, and increase the dose as needed to achieve anti-factor Xa levels 0.1 to 0.5 international units/mL. The maximum single dose should not exceed 100 mg.

-If unfractionated heparin is used, we suggest 5000 units subcutaneous injection every eight hours.

Patients who require prolonged anticoagulation can be switched over to an oral agent (eg, warfarin [can be used in breastfeeding women] or a direct oral anticoagulant [should not be used if breastfeeding]). (See "Use of anticoagulants during pregnancy and postpartum", section on 'Postpartum and breastfeeding'.)

Recommendations of others

ACCP recommendations — This is a partial synopsis of 2012 ACCP guidelines for antithrombotic therapy and prevention of thrombosis in pregnancy [98]:

●For women whose only risk factors for VTE are pregnancy and cesarean birth, the ACCP recommends only early ambulation postpartum.

●For women undergoing cesarean birth with one additional major risk factor for VTE or at least two additional minor risk factors for VTE, the ACCP recommends pharmacologic thromboprophylaxis while in the hospital following delivery. If anticoagulants are contraindicated, graduated compression stockings or a pneumatic compression device is recommended.

●For women undergoing cesarean birth who are very high risk for VTE and have multiple additional risk factors for VTE that persist in the puerperium, the ACCP recommends pharmacologic thromboprophylaxis PLUS graduated compression stockings and/or pneumatic compression devices while in the hospital following delivery.

●For selected high-risk women in whom significant risk factors persist following delivery, the ACCP suggests extended pharmacologic prophylaxis for up to 6 weeks after delivery following discharge from the hospital.

In 2016, several of the ACCP authors slightly revised the original risk factor criteria [114]. Their most recent guidance for prevention of VTE after cesarean birth states:

Prophylaxis should be provided after cesarean birth to women with the following risk factors:

●One or more of: prior VTE, history of antepartum immobilization (strict bedrest for at least 1 week), significant postpartum infection, postpartum hemorrhage ≥1000 mL requiring reoperation, preeclampsia with growth restriction, significant medical co-morbidities (systemic lupus erythematosus, heart disease, or sickle cell disease), or a known thrombophilia.

●Two or more of (or one or more in the setting of emergency cesarean birth): postpartum hemorrhage ≥1000 mL not requiring reoperation, BMI >30 kg/m², fetal growth restriction, preeclampsia, multiple pregnancy, and tobacco use during pregnancy (≥10 cigarettes/day).

RCOG recommendations — The Royal College of Obstetricians and Gynaecologists (RCOG) stated that "all women who have had caesarean sections should be considered for thromboprophylaxis with LMWH for 10 days after delivery, apart from those having an elective caesarean section who should be considered for thromboprophylaxis with LMWH for 10 days after delivery if they have any additional risk factors. Thromboprophylaxis should be continued for six weeks in high-risk women and for 10 days in intermediate-risk women" [109]. The RCOG considers the following risk factors for VTE (refer to RCOG guideline for detailed description of risk assessment): previous VTE, thrombophilia, some medical comorbidities (eg, cancer; heart failure; active SLE, inflammatory polyarthropathy, or bowel disease; nephrotic syndrome; type I diabetes mellitus with nephropathy; sickle cell disease; current intravenous drug user), age >35 years, BMI ≥30 kg/m², parity ≥3, gross varicose veins (symptomatic or above knee or with associated phlebitis, edema/skin changes), paraplegia, multiple pregnancy, preeclampsia, preterm birth, postpartum hemorrhage >1 L/requiring transfusion, admission/immobility ≥3 days, current systemic infection [109].

However, RCOG criteria for thromboprophylaxis after cesarean birth would apply to half of United States cesarean birth patients (1.2 million a year), and the drugs alone could cost up to USD $52 million for a 4-day course and USD $130 million for a 10-day course [97].

Preparation for postpartum hemorrhage — (See "Overview of postpartum hemorrhage", section on 'Planning'.)

One option for prophylaxis against postpartum hemorrhage is to administer tranexamic acid before making the incision for cesarean. (See "Management of the third stage of labor: Prophylactic drug therapy to minimize hemorrhage", section on 'Tranexamic acid'.)

Other issues to consider

●Bowel preparation is not beneficial and is not recommended [8,115].

●Surgery in women with severe obesity presents additional challenges that are discussed separately. (See "Cesarean birth: Patients with obesity".)

FETOPLACENTAL ASSESSMENT

Fetal heart rate monitoring — For women waiting to undergo a scheduled cesarean birth, the value of continuous or intermittent fetal heart rate monitoring following admission is unclear [116], no randomized trials examining this issue have been performed. At a minimum, the fetal heart rate should be documented upon admission, similar to other vital signs. If the pregnancy is high risk and has been undergoing antepartum fetal testing, it is reasonable to perform an admission nonstress test and discontinue monitoring if the tracing is reactive. If there is an excessive delay between anesthetic placement and abdominal preparation for surgery, it is appropriate to recheck the fetal heart rate during this interval.

For laboring patients, fetal heart rate monitoring should continue after transfer to the operating room, to the extent possible. External monitors are removed when the abdominal preparation is begun; internal monitors are removed when the abdominal preparation is completed.

Fetal presentation and placental location — An ultrasound for assessment of placental location and fetal presentation, or Leopold maneuvers to assess fetal presentation, may be useful before surgery, but not required. This information may help the surgeon avoid disturbing the placenta at hysterotomy and plan delivery of a fetus in nonvertex presentation.

INTRAOPERATIVE MATERNAL PREPARATION

Bladder catheterization — Most clinicians insert a urethral catheter at the start of the case to maintain bladder drainage and thereby improve visualization during surgery and minimize bladder injury. The catheter is also useful for instilling dye if a cystotomy is suspected and for monitoring urine output. Potential harms include an increased risk of urinary tract infection, urethral pain, voiding difficulties after removal of the catheter, delayed ambulation, and longer hospital stay [117].

However, there is no high quality evidence that routine placement of an indwelling catheter is advantageous [117,118]. As an alternative, patients at low risk of intraoperative complications can be asked to void shortly before entering the operating room. If subsequently required, an indwelling catheter can be inserted intraoperatively or postoperatively, and removed as soon as possible [119-122].

Hair removal — Meta-analyses of randomized trials in nonpregnant patients report no difference in the rate of surgical site infection (SSI) in those who had hair removed prior to surgery versus those who did not [123,124]. No randomized trials assessing this intervention specifically before cesarean birth have been performed.

If hair needs to be removed, it should be clipped rather than shaved as patients who are shaved are more likely to develop SSI. Use of a depilatory cream is also preferable to shaving. Clipping should be performed just before surgery. (See "Overview of control measures for prevention of surgical site infection in adults", section on 'Hair removal'.)

Skin preparation — We prepare the abdominal surgical site with a chlorhexidine-alcohol scrub before cesarean birth based on data from three randomized trials that reported a reduction in SSI or positive bacterial wound cultures compared with iodine-alcohol skin preparation; two trials were in women undergoing cesarean birth [125,126] and the other in adults undergoing clean-contaminated surgery [127]. However, a 2020 meta-analysis of randomized trials evaluating skin preparation techniques concluded there was insufficient evidence overall for determining the most effective skin preparation technique for preventing post-cesarean SSI or for reducing other undesirable outcomes [128], suggesting either chlorhexidine-alcohol or iodine-alcohol is reasonable. Of note, in the subanalysis comparing chlorhexidine-alcohol versus povidone-iodine, chlorhexidine-alcohol was more effective in reducing SSI (risk ratio [RR] 0.72, 95% CI 0.58-0.91, eight trials, 4323 women), but the difference was attenuated when four trials at high risk of bias were removed. The American College of Obstetricians and Gynecologists and the Enhanced Recovery After Surgery (ERAS) Society guideline for intraoperative care in cesarean birth recommend use of an alcohol-based mixed solution such as chlorhexidine-alcohol [9,55].

Alcohol-based surgical prep solutions contain approximately 70 to 75 percent isopropyl alcohol and serve as fuels if not allowed to dry sufficiently before use of an ignition source; at least three minutes are required. Therefore, preparation with povidone-iodine or chlorhexidine soap (eg, Hibiclens) is advantageous when surgery cannot be delayed, as these solutions are not flammable.

Vaginal preparation — For women in labor and women with ruptured membranes, we perform a 4% chlorhexidine gluconate vaginal scrub with a sponge stick for 30 seconds with three passes to lower SSI risk, particularly endometritis. Povidone-iodine is an alternative option but was less effective in the largest randomized trial comparing these two options [129]. Preparations with a high alcohol content (chlorhexidine gluconate with 70% alcohol used for skin preparation) should be avoided in the vagina because alcohol irritates mucous membranes [55].

In a 2020 meta-analysis of randomized trials of vaginal cleansing (povidone-iodine or chlorhexidine) versus placebo/no intervention before cesarean birth, vaginal cleansing resulted in reductions in endometritis (3 versus 7.2 percent, RR 0.41, 95% CI 0.29-0.58), postoperative fever (RR 0.64, 95% CI 0.50-0.82), and wound infection (3.8 versus 6.1 percent, RR 0.62, 95% CI 0.50-0.77) [130]. In subgroup analysis, women who were in labor or had rupture of membranes had the largest reduction in postoperative endometritis; however, the interaction tests for subgroup differences were not statistically significant. Neither cleansing agent resulted in adverse effects.

A network meta-analysis of randomized trials confirmed that all antiseptic formulations (povidone-iodine, chlorhexidine, metronidazole gel, cetrimide) decreased the rate of endometritis compared with placebo (5.2 versus 9.1 percent, odds ratio [OR] 0.48, 95% CI 0.35-0.65); povidone-iodine had the highest probability of reducing the risk of endometritis, postoperative wound infections, and fever [131]. However, in the only trial that compared wound infection rates in patients assigned to chlorhexidine versus povidone-iodine before cesarean birth, the rate was lower in the chlorhexidine arm (0.6 versus 2 percent, OR 0.28, 95% CI 0.08-0.98) [129], which is the basis for our preference for chlorhexidine. Endometritis rates were low and similar in both arms (0.4 and 0.5 percent).

Nonadhesive drapes — The surgical site is draped with nonadhesive drapes as two randomized trials in patients undergoing cesarean birth reported that these drapes resulted in a lower rate of wound infection than adhesive drapes [132,133].

Uterine displacement — The uterus is typically displaced at least 15 degrees to the left to reduce aortocaval compression ("supine hypotensive syndrome"), which occurs in the supine position when the uterus is at or above the umbilicus [134-138]. A foam or wood wedge, pillow, or rolled blanket may be used, or the table can be tilted, or the uterus can be manually displaced. A 2013 systematic review was not able to determine the optimum method or maternal position [139]. (See "Anesthesia for cesarean delivery", section on 'Intraoperative positioning'.)

Perioperative management of medication — Perioperative medication is similar to that for other surgical procedures, and discussed separately. (See "Perioperative medication management".)

Room temperature — Normothermia should be maintained during anesthesia and surgery. Patients receiving neuraxial anesthesia become hypothermic to a degree that is similar to those having general anesthesia. (See "Perioperative temperature management".)

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Cesarean birth".)

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5^th to 6^th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10^th to 12^th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

●Basics topics (see "Patient education: C-section (cesarean delivery) (The Basics)")

●Beyond the Basics topics (see "Patient education: C-section (cesarean delivery) (Beyond the Basics)")

SUMMARY AND RECOMMENDATIONS

●Cesarean birth is performed when the clinician and patient believe that abdominal delivery is likely to provide a better maternal or fetal outcome than vaginal delivery. A wide variety of conditions fulfill these criteria. (See 'Indications' above.)

●Scheduled/planned primary cesarean birth at term should be performed in the 39^th or 40^th week of gestation rather than in the 37^th or 38^th week. Medically/obstetrically indicated cesarean births are performed when clinically indicated. (See 'Scheduling' above.)

●Timing of scheduled/planned repeat cesarean birth is based on the type of previous hysterotomy incision and is reviewed separately. (See "Repeat cesarean birth", section on 'Timing'.)

●For all women undergoing cesarean birth, we recommend preoperative antibiotic prophylaxis rather than no prophylaxis or prophylaxis after cord clamping (Grade 1A). Antibiotics are given up to 60 minutes before making the incision.

•We use a single intravenous dose of a narrow-spectrum antibiotic, such as cefazolin (2 grams for patients <120 kg and 3 grams for patients ≥120 kg). Multiple doses are more costly, without clearly improving outcome in the absence of prolonged surgery or excessive blood loss. If the cesarean birth is performed intrapartum or after rupture of membranes, we add a dose of azithromycin 500 mg intravenously. (See 'Regimen' above and 'Prolonged surgery or excessive blood loss' above.)

•For women with a history of serious forms of penicillin allergy, we substitute clindamycin and gentamicin for cefazolin. Women at low risk of a serious immediate allergic reaction can receive cefazolin. If the cesarean birth is performed intrapartum or after rupture of membranes, we add a dose of azithromycin 500 mg intravenously. (See 'Women with penicillin allergy' above.)

•For women already receiving penicillin G for prophylaxis of neonatal Group B Streptococcus (GBS) infection, we do not add cefazolin or switch to ampicillin for surgical prophylaxis. If the cesarean birth is performed intrapartum or after rupture of membranes, we add a dose of azithromycin 500 mg intravenously. (See 'Woman already on antibiotics' above.)

•For women receiving ampicillin and gentamicin for chorioamnionitis, we add either one dose of clindamycin 900 mg or metronidazole 500 mg before making the incision, and continue ampicillin and gentamicin or switch to ampicillin-sulbactam postpartum until the patient is afebrile for at least 24 hours. Bacteroides resistance to clindamycin is increasing; in areas of high resistance, ampicillin-sulbactam is preferable. We do not administer pre-incision prophylactic azithromycin in this setting. (See 'Woman already on antibiotics' above.)

●We use a chlorhexidine-based antiseptic agent rather than an iodine-based antiseptic agent for skin preparation, but either approach is reasonable. Chlorhexidine-alcohol solutions should be allowed to dry for at least three minutes before using an ignition source, otherwise a nonflammable preparation (povidone-iodine or chlorhexidine soap) should be used. (See 'Skin preparation' above.)

●For women in labor and women with ruptured membranes, we suggest vaginal cleansing before cesarean birth rather than no vaginal cleansing (Grade 2C). We use a 4% chlorhexidine gluconate vaginal scrub, but povidone-iodine is also reasonable. Vaginal cleansing in these high-risk populations reduces the frequency of postpartum endometritis. (See 'Vaginal preparation' above.)

●For all women undergoing cesarean birth, we suggest mechanical thromboprophylaxis (Grade 2C). For women undergoing cesarean birth at high risk of venous thromboembolism (VTE), we suggest mechanical thromboprophylaxis plus pharmacologic thromboprophylaxis (Grade 2C). Pharmacologic prophylaxis is begun 6 to 12 hours postoperatively, after concerns for hemorrhage have decreased. Mechanical and pharmacologic prophylaxis are continued until the woman is fully ambulating. Women with significant risk factors for VTE persisting following birth should receive a full six weeks of thromboprophylaxis. (See 'Thromboembolism prophylaxis' above.)

●During cesarean birth, the uterus is displaced at least 15 degrees to the left to reduce aortocaval compression. (See 'Uterine displacement' above.)