It is not uncommon for pregnant women to undergo invasive diagnostic or therapeutic procedures, including surgical operations. In these cases, gravidas present a dual challenge. Namely, the risks and benefits of a proposed procedure for the mother are balanced against the potential fetal risks and benefits associated with the proposed operation.

This evaluation begins with a detailed maternal history and clinical examination, indicated laboratory testing, and appraisal of fetal status. Preoperative assessment ideally identifies obstetric and medical risks that may be associated with perioperative maternal or fetal morbidity and mortality. Recognition of risks and benefits allows providers to adequately counsel a gravida and permits shared decision making and informed consent. This often requires a collaborative effort with input from anesthesiologists, obstetricians, pediatricians, neonatologists, and associated surgeons. Even so, despite improved obstetric, surgical, and medical care, all operative procedures carry risk.

Maternal Assessment

To begin, an inventory of medical comorbidities is assembled. Some may be of greater importance for the surgical patient. Cardiopulmonary status, which undergoes profound physiologic changes during pregnancy, may be particularly vulnerable during surgery and should be an area of increased focus. A summary of these normal changes in the gravida is found in Chapter 19 (p. 307). Of other clinical points, baseline anemia may increase needs for transfusion. Diabetes mellitus and smoking can elevate wound infection complication risks. Women with prior venous thromboembolism have greater chances for recurrence, especially with long pelvic or orthopedic surgeries. Surgery poses added physical strain, and gravidas taking large doses of corticosteroids may benefit from perioperative stress dosing. Last, a patient’s religious beliefs, such as with Jehovah’s Witnesses, may limit blood transfusion options.

During physical examination, basic components are completed. Again, cardiopulmonary status is a primary focus. The airway is assessed as described on page 293, and spine inspection should investigate for scoliosis. Aberrations in these areas may merit special anesthesia consultation. Patient body habitus also alters surgical risks. For example, obese patients have diminished pulmonary reserve, and their pannus can influence incision selection. Underweight patients may be at greater risk for nerve injury if not correctly positioned when anesthetized in dorsal lithotomy position for an extended time. Digital cervical assessment to determine dilatation or effacement may be helpful prior to some surgeries that pose a risk for associated preterm labor. Examples include cervical cerclage or fetal surgery, discussed in Chapters 11 and 16, respectively.

Laboratory Assessment

For most healthy pregnant women, laboratory testing prior to surgery can be minimal. A complete blood count; chemistry panel that evaluates electrolytes, renal function, and glucose levels; and type and screen are common for procedures with associated blood loss risks. For cases with greater anticipated bleeding, such as with placenta previa or the accrete syndrome, a type and crossmatch is prudent. In women without prior prenatal care, blood typing to clarify Rh status is also completed.

Surgical Route Selection

Unlike gynecology, in which similar procedures may be completed vaginally or abdominally, procedures in obstetrics typically fall clearly into one approach or the other. For those that require abdominal entry, many nonobstetric procedures can be completed by a minimally invasive surgical (MIS) route. Examples include adnexal surgery, appendectomy, and cholecystectomy. This is also true for many fetal surgery procedures. Thus, an initial preoperative decision is the route of surgery.

When feasible, MIS offers the advantages of faster patient recovery, shorter hospital stays, lower postoperative ileus rates, less postoperative pain, and fewer wound complications (Nieboer, 2009; Pearl, 2011). However, not all cases are suitable. First, for a given procedure, MIS may not provide sufficient access to the uterus. Cesarean delivery is an obvious example. Other limits can include known dense adhesive disease, surgeon skill, or facility barriers. Also, large bulky pathology may be difficult to remove or may encroach on needed operating space. As described in Chapter 15 (p. 240), laparoscopy creates unique physiologic changes, which may be incompatible with some maternal cardiopulmonary comorbidities. Also, MIS can require longer operating times, which can expose the mother or fetus to undesirable effects of anesthesia or pneumoperitoneum. Thus, for many cases in pregnancy, laparotomy is required.

Laparotomy Incision Selection

In cases warranting laparotomy, a surgeon must select either a low transverse or midline vertical abdominal wall incision for entry. A thorough discussion of these incisions and their characteristics is found in Chapter 4 (p. 49). Briefly, low transverse incisions are often preferred as they produce good cosmetic results and are also less painful. Additionally, these incisions are placed in the lower abdomen and interfere less with postoperative respiratory movement, thereby aiding easier recovery. Transverse incisions, however, do have disadvantages compared with midline vertical ones. Drawbacks are that: (1) the intraabdominal operative space is smaller; (2) the ability to extend the incision is limited; (3) the division of multiple layers of fascia and muscle creates dead spaces for blood or pus to accumulate; (4) surgical bleeding is comparatively greater; and (5) the time required to enter the abdomen is typically longer.

Anesthesia Selection

Many obstetric procedures can be completed under local paracervical or pudendal blockade; under neuraxial anesthesia that includes spinal, epidural, or combined spinal-epidural anesthesia; or under general anesthesia. A more detailed discussion of their indications and illustrations are found in Chapters 9 and 19 (p. 136 and 309).

Briefly, local blocks are suitable for small localized surgeries such as perineal laceration repair. When coupled with intravenous (IV) sedation, these can also be selected for dilatation and curettage. Regional anesthesia is preferred for labor, for operative vaginal delivery, or for cesarean delivery. General anesthesia is often needed for emergency surgery, for laparoscopy, for surgery extending into the upper abdomen, or for cases requiring greater intraabdominal organ manipulation.

Fetal Assessment

Of fetal parameters, gestational age, fetal presentation, and placental location are important elements to consider. Of these, gestational age profoundly affects surgical decision making. Examples are numerous and found throughout this text. First, indicated but nonurgent surgeries are often delayed until the second trimester. Abortion techniques and risk vary considerably between the first and second trimester. Previable gestations are typically excluded from cesarean delivery for fetal indications. In contrast, cervical cerclage is rarely offered after 24 weeks’ gestation. Thus, gestational age should be assessed using both last menstrual period and sonographic fetal measurements.

A second parameter, fetal presentation, is most important prior to external version attempts, twin delivery, vaginal breech delivery, and cesarean delivery. This is most often determined sonographically.

A third parameter, placental location, is valuable information prior to cesarean delivery. With an anterior placenta, low transverse hysterotomy may concurrently incise the placenta. This in turn can abruptly lower perfusion to the fetus. Thus, in such cases, expedient fetal delivery is planned. Placenta location can also influence many fetal therapy procedures that often insert needles or trocars through the anterior uterine wall.

If delivery is not planned but significant uterine manipulation may be expected, preoperative sonography is also necessary to determine fetal position, placental location, and planning for the appropriate uterine incision should an unexpected delivery be required.

Preoperative Consultation

Depending on the scheduled surgical procedure, additional preoperative considerations may include multidisciplinary consultation from medical and surgical specialists to be involved in the surgery. Examples include staff from anesthesiology, urology, gynecologic oncology, general surgery, blood banking, and intensive care units for the mother or neonate.

Preoperative anesthesia consultation should include a review of the history, clinical examination, and preoperative laboratory testing. The woman’s history provides information to assess the physical state prior to selecting an anesthetic and prior to performing a surgery. The American Society of Anesthesiologists (ASA) introduced a simple grading system to describe the patient’s general health. Notably, the ASA Physical Status Classification System is not intended to be used to predict operative risk. Table 18-1 summarizes the current classification as approved the ASA House of Delegates.

Clinical examination prior to initiation of anesthesia allows evaluation of the airway status with the intent to detect physical characteristics that may predict a difficult airway. Components of the preoperative airway physical examination are listed in Table 18-2 with the Mallampati evaluation. Figure 18-1 depicts this classification.

As discussed in Chapter 27 (p. 446), women undergoing cesarean delivery with suspected morbidly adherent placenta should be managed by an experienced multidisciplinary team in a tertiary care center. Care here ensures the capability to provide large amounts of blood products and implement appropriate intensive intra- and postoperative care when indicated (Silver, 2015). Additional preoperative consultations might include blood bank notification of possible need for massive transfusions. Also, a urologist or gynecologic oncologist may be enlisted to perform intraoperative cystoscopy, to thread ureteral stents, or rarely to resect a portion of the bladder invaded by a percreta. Preoperatively, an interventional radiologist may be consulted to insert balloon catheters into the internal iliac arteries. These can be inflated intraoperatively to stem massive pelvic bleeding.

In such multidisciplinary cases, a preoperative checklist is suggested to confirm that all notifications are complete. This should also provide readily available names with contact information of potential consultants (American College of Obstetricians and Gynecologists, 2016b; Society for Maternal-Fetal Medicine, 2010).

Timing of Nonobstetric Procedures

Considerations for the timing of nonobstetric surgery during pregnancy depend on gestational age and the indication for the surgery. Urgently indicated operations—for example, acute appendicitis—should be performed without regard to gestational age. If the procedure is judged to be indicated during pregnancy but nonurgent, most recommend performing the procedure during the second trimester. This timing minimizes possible teratogen exposure during early embryofetal development. Also, the greatest potential for spontaneous miscarriage has passed. Elective surgery is delayed until the postpartum period (American College of Obstetricians and Gynecologists, 2015b).

Informed Consent

This is a process of communication in which the woman is presented with a comprehensible discussion regarding the diagnosis, recommended treatment, risks and benefits of the proposed procedure, alternative options, and the risks of not proceeding with the recommended treatment. The language of the consent should be understandable, and the patient should be encouraged to ask questions. For non-English-speaking patients, translation should be performed using skilled medical interpreters. Importantly, formal informed consent translation should not be provided by family members. Obtaining consent may also involve agreement to participate in medical research or to accept possible involvement in teaching exercises when appropriate. Many consent forms include routine patient approval for medical photography.

Despite a clinician’s recommendations, an informed patient may decline a particular intervention. A woman’s decision-making autonomy must be respected, and a clinician documents informed refusal in the medical record. Appropriate documentation includes: (1) a patient’s refusal to consent to the recommended intervention, (2) notation that the value of the intervention has been explained to the patient, (3) a patient’s reasons for refusal, and (4) a statement describing the health consequences as described to the patient.

Surgical Site Infection Prevention

Surgical site infections (SSIs) are among the most frequent complications associated with operations. Infections can lead to significantly increased hospital length of stay, morbidity, and mortality. Among the various strategies reported to prevent SSI, antibiotic prophylaxis has been shown to reduce postoperative infectious morbidity by 60 to 70 percent (Smaill, 2014; Witt, 2011).

Clinical criteria used to justify perioperative antibiotic prophylaxis include: (1) surgical procedure involving a contaminated operative field, (2) operations with a high incidence of postoperative infection, and (3) complications associated with SSIs that are potentially severe, for example, pelvic or abdominal abscess (Duff, 1987). These criteria are reflected in the accepted surgical wound classification, which categorizes wounds according to the degree of contamination and likelihood of subsequent infection (Table 18-3).

In this system, a clean wound is defined as an uninfected wound without inflammation in which the respiratory, alimentary, genital, or uninfected urinary tracts are not entered. Adnexectomy or puerperal sterilization would fall into this category.

A clean-contaminated wound is an operative wound in which the respiratory, alimentary, genital, or urinary tracts are entered under controlled conditions without unusual contamination. Clean-contaminated wounds assume no evidence of infection or break in technique (Mangram, 1999). Antibiotic prophylaxis is indicated for certain obstetric clean-contaminated procedures such as cesarean delivery and may be indicated for contaminated wounds such as vaginal delivery complicated by severe perineal lacerations. Antibiotic prophylaxis would not otherwise be indicated for most vaginal deliveries.

Contaminated wounds reflect operations with major breaks in sterile technique or gross gastrointestinal spillage or incisions in which acute, nonpurulent inflammation is encountered (Mangram, 1999). Subsequent infection rates are significant. For this reason, a minimum of 24 hours of perioperative antibiotic administration is suggested.

An infected or dirty wound implies that bacteria are already present when the surgical incision is made. A common example is the wound involving a cesarean delivery complicated by chorioamnionitis. In this case, prophylactic antibiotics are not given, but instead therapy is continued with antibiotic agents begun for chorioamnionitis.

Of note, patients undergoing certain clean surgical procedures may benefit from antibiotic prophylaxis in situations in which the consequences of infection may be severe. Examples might include incisions involving prosthetic implants or immunocompromised patients (Bratzler, 2013).

Principles of Antibiotic Prophylaxis

Considerations for antibiotic prophylaxis have been developed by a collaborative effort involving the American Society of Health-System Pharmacists (ASHP), the Infectious Disease Society of America (ISA), the Surgical Infection Society (SIS), and the Society for Healthcare Epidemiology of America (SHEA) (Bratzler, 2013).

Antibiotic Agent Selection

The choice of antibiotic prophylaxis is based on patient- and procedure-specific considerations, known institutional-specific factors, the safety profile of the medication, and fetal risks from exposure to the antibiotic agent. The selected antibiotic should possess the narrowest spectrum of activity with proven efficacy to prevent infection. Thus, because of its spectrum of activity against most commonly encountered organisms resulting in SSIs, proven efficacy as an agent of prophylaxis, low cost, and safety profile, a first-generation cephalosporin is the preferred agent for most obstetric operative procedures such as cesarean delivery (Duff, 1987). This is administered intravenously. For prophylaxis following dilatation and curettage, however, oral doxycycline or metronidazole is recommended (p. 302).

Patients with a history of penicillin allergy but without a type 1 or immunoglobulin E (IgE) mediated reaction may safely receive a cephalosporin or carbapenem. Type 1 reactions include anaphylaxis, urticaria, bronchospasm, or exfoliative dermatitis. Those patients with a history of type 1 (IgE-mediated) allergic reaction from penicillin, cephalosporin, or carbapenem should instead receive a β-lactam antibiotic alternative. For cesarean delivery, the alternative is clindamycin in combination with an aminoglycoside.

Patients with known methicillin-resistant Staphylococcus aureus (MRSA) colonization should receive a single dose of vancomycin in addition to the standard antibiotic prophylaxis. Importantly, vancomycin MRSA prophylaxis does not replace standard antibiotic surgical prophylaxis (Bratzler, 2013).

Administration of antibiotic prophylaxis should be within 60 minutes prior to surgical incision. Agents requiring a longer period of administration, such as vancomycin and fluoroquinolones, should begin 120 minutes prior to surgical incision.

Dosing Antibiotic Prophylaxis

Antibiotic prophylaxis requires that adequate serum and tissue levels be delivered prior to the operative incision and that concentrations persist throughout the entire operation. Dosing considerations include body weight, surgery duration, intraoperative blood loss, and renal function.

Obese women present several problems for antibiotic prophylaxis. The prevalence of obesity in the United States has remained stable through 2012. Specifically, 35 percent of adults have a body mass index (BMI) ≥30, and 6.4 percent have a BMI ≥40 (Ogden, 2012). Antibiotic dose adjustments based on body weight are considered due to an increased volume of distribution. Also, drug-clearance pharmacokinetics are altered, which can raise SSI risks. However, only limited data are available to define the optimal method of weight-based dosing in these women. For example, the use of actual body weight may result in excessive serum and tissue concentrations when dosing with a hydrophilic medication such as an aminoglycoside. Conversely, the use of ideal body weight may result in subtherapeutic concentrations of a lipophilic medication such as vancomycin (Bratzler, 2013).

Proven recommendations for weight-based dosing of antibiotic agents in the obese patient that result in decreased SSI rates are not available (Pai, 2007; Wurtz, 1999). That said, recent guidelines suggest increasing the standard 1-g dose of cefazolin to 2 g for women weighing more than 80 kg and using a 3-g dose for patients weighing more than 120 kg (Bratzler, 2013).

When gentamicin is selected in combination with an additional antibiotic for prophylaxis, the recommended dose is 4.5 to 5 mg/kg given as a single dose. However, the decision on which weight-based formula to use remains uncertain. For obese patients weighing more than 20 percent above their ideal body weight (IBW), the ASHP and others recommend that the single dose of gentamicin given preoperatively should be calculated using a dosing weight (DW) (Bauer, 1983; Bratzler, 2013). This DW is their ideal body weight plus 40 percent of the difference between their actual (ABW) and ideal body weight (IBW).

In the obese patient, others recommend using gentamicin 5 to 7 mg/kg of IBW with a maximum dosage of 480 to 640 mg (Janson, 2012).

In some situations, an additional antibiotic dose may be required to ensure adequate serum and tissue concentrations throughout the procedure. Examples include procedure lengths that exceed two half-lives of the antibiotic agent or procedures associated with excessive blood loss. In patients with known renal insufficiency or renal failure that prolongs the antibiotic half-life, additional doses may not be indicated. The recommended doses and redosing intervals for commonly used antibiotics for surgical prophylaxis are included in Table 18-4.