American Society of Anesthesiologists Guidelines

The American Society of Anesthesiologists (ASA) has published Practice Guidelines for Obstetric Anesthesia, which includes a discussion of postpartum tubal ligation (see Appendix B ). The Task Force recommendations can be summarized as follows:

• 1.
  

  Before a postpartum tubal ligation, the patient should have no oral intake of solid foods within 6 to 8 hours of the surgery, depending on the type of food ingested (e.g., fat content).

  
  
• 2.
  

  Consider aspiration prophylaxis.

  
  
• 3.
  

  Both the timing of the procedure and the decision to use a specific anesthetic technique (i.e., neuraxial versus general) should be individualized, based on anesthetic and obstetric risk factors (e.g., blood loss at delivery), and patient preferences.

  
  
• 4.
  

  Consider selecting neuraxial techniques in preference to general anesthesia for most postpartum tubal ligations.

  
  
• 5.
  

  Be aware that gastric emptying will be delayed in patients who have received opioids during labor.

  
  
• 6.
  

  Be aware that an epidural catheter placed for labor may be more likely to fail with longer postdelivery time intervals.

  
  
• 7.
  

  If a postpartum tubal ligation is to be performed before the patient is discharged from the hospital, do not attempt the procedure at a time when it might compromise other aspects of patient care on the labor and delivery unit.

Surgical Considerations

Tubal sterilization can be performed satisfactorily at any time, but the early postpartum period has several advantages for women who have had an uncomplicated vaginal delivery. The patient avoids the cost and inconvenience of a second hospital visit. The uterine fundus remains near the umbilicus for several days postpartum, which allows easy access to the fallopian tubes via a mini-laparotomy. Mini-laparotomy and laparoscopy have similar rates of serious complications (e.g., bowel laceration, vascular injury), although postpartum tubal ligation is associated with lower failure rates than interval laparoscopic tubal ligation. Finally, costs may be lower with postpartum mini-laparotomy.

There are at least two potential disadvantages to immediate postpartum sterilization. First, parous women are at increased risk for uterine atony and postpartum hemorrhage. This risk decreases substantially 12 hours after delivery. Second, immediate surgery results in sterilization before assessment of the newborn is complete. Postpartum tubal ligation is not wise if the patient is ambivalent regarding permanent sterilization. However, women who undergo postpartum sterilization have a similar probability of regret within 1 year of delivery (23.7%) as women who undergo interval sterilization (22.3%), although the risk is markedly increased when the woman is younger than 25 years of age. Women should be counseled about failure, regret, and alternatives. Younger age and lower parity should not be a barrier to sterilization.

Several techniques are used for postpartum tubal sterilization ( Fig. 25.1 ). Puerperal sterilization has a failure rate that is lower than most interval procedures, and the failure rate is lowest (approximately 0.75%) if some form of tubal resection occurs. With the Irving procedure, the obstetrician buries the cut ends of the tubes in the myometrium and mesosalpinx. This technique is least likely to fail, but it requires more extensive exposure and increases the risk for hemorrhage. The Pomeroy procedure is simplest. The surgeon ligates a loop of oviduct and excises the loop above the suture. With the Parkland procedure, the obstetrician ligates the tube proximally and distally and then excises the mid-segment. The last two methods are most commonly performed during postpartum tubal ligations. Regardless of the technique, the obstetrician should document that fimbriae are present to preclude ligation of another structure such as the round ligament. The excised portions typically are sent to a pathologist for verification. Recently, surgical technique has changed and instead of performing a tubal ligation for sterilization some surgeons are recommending a salpingectomy because bilateral salpingectomy reduces the incidence of ovarian cancer to a greater degree than tubal ligation, and it adds only approximately 10 minutes to the procedure without additional complications.

Techniques for tubal sterilization. (A) Irving procedure. The medial cut end of the oviduct is buried in the myometrium posteriorly, and the distal cut end is buried in the mesosalpinx. (B) Pomeroy procedure. A loop of oviduct is ligated, and the knuckle of tube above the ligature is excised. (C) Parkland procedure. A mid-segment of tube is separated from the mesosalpinx at an avascular site, and the separated tubal segment is ligated proximally and distally and then excised. (D) Madlener procedure. A knuckle of oviduct is crushed and then ligated without resection; this technique has an unacceptably high failure rate of approximately 7%. (E) Kroener procedure. The tube is ligated across the ampulla, and the distal portion of the ampulla, including all of the fimbria, is resected; some studies have reported an unacceptably high failure rate with this technique.

(From Cunningham FG, Leveno KJ, Bloom SL, et al., eds. Williams Obstetrics , 24th ed. Columbus, OH: McGraw-Hill Education; 2014:720–727.)

Nonmedical Issues

Nonmedical issues affect decisions regarding the timing of tubal sterilization. The obstetrician must obtain and document informed consent for surgery. Tubal ligation should be considered an irreversible procedure. Therefore, most obstetricians require a discussion with the patient before labor and delivery. Physicians should be aware of state laws or insurance regulations that may require a specific interval between obtaining consent and performance of sterilization procedures. Regulations often do not allow the woman to give consent while in labor or immediately after delivery. For example, the Medicaid reimbursement program includes the following requirements for sterilization :

• •
  

  The patient must be at least 21 years of age and mentally competent when consent is obtained.

  
  
• •
  

  Informed consent may not be obtained while the patient is in labor or during childbirth.

  
  
• •
  

  Consent may not be obtained while the patient is undergoing an abortion or under the influence of alcohol or other substances.

  
  
• •
  

  A total of 30 days must pass between the date the consent is signed and the date the procedure is performed. (Exceptions to the 30-day waiting period can be made for preterm delivery or emergency abdominal surgery.)

  
  
• •
  

  Consent is valid for only 180 days.

An ethical analysis of the Medicaid sterilization consent regulations notes: “…the regulations are ethically flawed: by preventing women from accessing needed family planning services, the Medicaid consent rules violate the standards of beneficence and non-maleficence; by treating publically insured women differently from privately insured women, they fail the justice standard; and by placing constraints on women’s free choice of contraceptive methods, they run afoul of the autonomy standard.”

In some cases the obstetrician may schedule a patient for a postpartum tubal sterilization because of a fear that the patient will not return for interval tubal sterilization 6 weeks after delivery. Concerns regarding patient compliance should not prompt the performance of postpartum tubal sterilization in patients with significant medical or obstetric complications. However, women who request postpartum tubal sterilization but do not receive it are more likely to become pregnant within 1 year of delivery (46.7%) than are women who did not request the procedure (22.3%).

The American College of Obstetricians and Gynecologists (ACOG) has stated that given the consequences of a missed procedure and the limited time frame in which it may be performed, postpartum sterilization should be considered an urgent surgical procedure. They also stated that obstetrician-gynecologists should identify and eliminate barriers that restrict access to postpartum sterilization. The ACOG concluded that obstetrician-gynecologists should be champions or patient advocates for postpartum sterilization in their respective hospitals and help to coordinate administration and health care staff in streamlining access to the procedure. Increasing access and availability of postpartum sterilization may not only directly improve outcomes for women desiring the procedure, but may decrease overall costs to the health care system.

Preoperative Evaluation

The patient scheduled for postpartum tubal sterilization requires a thorough preoperative evaluation, and a reevaluation should be performed even if the patient is known to the anesthesia provider as a result of the provision of labor analgesia. A cursory evaluation should not be performed simply because the patient is young and healthy. Patients with preeclampsia may safely receive neuraxial or general anesthesia for postpartum tubal sterilization provided that there is no evidence of pulmonary edema, oliguria, or thrombocytopenia.

Physicians and nurses often underestimate blood loss during delivery. Excessive blood loss from uterine atony is not uncommon in parous women. Orthostatic changes in blood pressure and heart rate should be excluded, especially if an immediate postpartum procedure is to be performed. At the University of Colorado, for surgery performed the day after delivery, the patient’s hematocrit is determined several hours after delivery (to allow for equilibration) and compared with the antepartum measurement. A hematocrit is not obtained before an immediate postpartum tubal sterilization (performed less than 8 hours after delivery), provided that the antepartum hematocrit was acceptable, there are no orthostatic vital sign changes, and there was no evidence of excessive blood loss during delivery.

No absolute value of hematocrit requires a delay of surgery, but physical signs of hemodynamic instability or laboratory evidence of excessive blood loss should prompt postponement of the procedure until 6 to 8 weeks postpartum. Fever may signal the presence of endometritis or urinary tract infection and may also require postponement of surgery until a later date. Finally, the condition of the neonate should be confirmed before surgery to exclude any unexpected problems.

Mothers may be concerned that medications administered during surgery might affect their ability to breast-feed or that these medications might harm the newborn. Any drug present in the mother’s blood will be present in breast milk, with the concentration dependent on factors such as protein binding, lipid solubility, and degree of ionization. Typically, the amount of drug present in breast milk is small. Opioids, barbiturates, and propofol administered during anesthesia are excreted in insignificant amounts. (See Chapter 14 for a detailed discussion of interactions between drugs and breast-feeding.)

Risk for Aspiration

Historically, anesthesiologists have considered maternal aspiration the major risk associated with anesthesia for postpartum tubal sterilization, although the evidence for this is scant and conflicting. A review of anesthesia-related maternal mortality found no maternal deaths associated with aspiration during postpartum tubal ligation, despite tracking deaths for an entire year after delivery. A review of serious complications related to obstetric anesthesia sponsored by the Society for Obstetric Anesthesia and Perinatology also did not identify any cases of maternal death related to aspiration during postpartum tubal ligation. However, several factors may place the pregnant woman at increased risk for aspiration. Some but not all of these factors are resolved at delivery. The placenta is the primary site of progesterone production, and progesterone concentrations fall rapidly after delivery of the placenta ( Fig. 25.2 ). Typically, progesterone concentrations decline within 2 hours of delivery; and by 24 hours postpartum, progesterone concentrations are similar to those found during the luteal phase of the menstrual cycle.

Average progesterone concentrations with the highest and lowest measurements of 13 pregnant women at given time intervals.

(From Llauro JL, Runnebaum B, Zander J. Progesterone in human peripheral blood before, during and after labor. Am J Obstet Gynecol. 1968;101:871.)

Two important questions to address during the preanesthetic evaluation are (1) What is the duration of the fast for solids? (2) Were parenteral opioids administered during labor?

Gastric Emptying

Several studies have assessed gastric emptying in pregnant and postpartum women. O’Sullivan et al. used an epigastric impedance technique to compare gastric emptying times for solids and liquids in women during the third trimester of pregnancy, in women during the first hour postpartum, and in nonpregnant controls. The investigators observed that the overall rate of gastric emptying was lower in the postpartum patients than in the pregnant or nonpregnant patients. However, when patients who had received parenteral opioids in labor were separated from those who had not, rates of gastric emptying for women who had not received opioids were similar to those for nonpregnant controls. The investigators concluded that the rate of gastric emptying in postpartum women is delayed only if opioids have been administered during labor.

Other studies have used the acetaminophen (paracetamol) absorption technique to assess gastric emptying. Gin et al. studied women on the first and third days after delivery and at 6 weeks postpartum. They found comparable times to peak concentration of acetaminophen in all three groups. They concluded that gastric emptying was no different in the immediate postpartum period than 6 weeks later, and they recommended that “the approach to prophylaxis against acid aspiration should be more consistent between nonpregnant and postpartum patients.”

Sandhar et al. used applied potential tomography to measure gastric emptying in 10 patients at term gestation, 2 to 3 days postpartum, and 6 weeks postpartum. The 6-week measurement served as each woman’s control value. All measurements were made after administration of an H ₂ -receptor antagonist. The times to 50% emptying after ingestion of 400 mL of water were not different among the three periods of testing ( Fig. 25.3 ).

Mean (SEM) times to 50% gastric emptying (min). No significant differences were noted between term pregnant, postpartum, and nonpregnant control women.

(From Sandhar BK, Elliott RH, Windram I, Rowbotham DJ. Peripartum changes in gastric emptying. Anaesthesia. 1992;47:197.)

Wong et al. assessed gastric emptying in nonlaboring pregnant women at term gestation, after ingestion of either 50 or 300 mL of water, by using two techniques: (1) serial assessment of acetaminophen absorption and (2) use of ultrasonography to determine gastric antrum cross-sectional areas. Gastric emptying was significantly faster after ingestion of 300 mL of water, consistent with the observation that a liquid meal may actually accelerate gastric emptying. Repeating the study in obese women showed similar results. Kubli et al. compared the effects of isotonic “sport drinks” versus water on residual gastric volume in women in early labor. Women who received isotonic sport drinks had similar gastric volumes and a similar incidence of vomiting as compared with those who received water, but the ingestion of sport drinks prevented the increase in ketone production that occurred in the control (water) group.

In contrast, Jayaram et al. found that 39% of women presenting for postpartum tubal ligation had solid food particles in the stomach, as demonstrated by ultrasonography, but they did not find solid food particles in a control group of nonpregnant women presenting for gynecologic surgery. They also found that 4 hours after a standardized meal in women not scheduled for surgery, 95% of postpartum women—compared with only 19% of nonpregnant subjects—still had solid food particles in the stomach. Prior administration of an opioid did not seem to be a risk factor in this study. Scrutton et al. randomized 94 women presenting in early labor to receive either a light diet or water only during labor. The mothers who ate a light diet had significantly larger gastric antrum cross-sectional areas (determined by ultrasonography) and were twice as likely to vomit at or around delivery as those who had water only. Also, the volumes vomited were significantly larger in the women who ate a light diet.

During the preoperative assessment of any woman scheduled for postpartum tubal sterilization, the anesthesia provider should determine when the patient last consumed solids and whether opioids were administered by any route. Systemic absorption of an opioid occurs after epidural administration. However, published studies have provided conflicting results regarding the effect of epidural opioid administration on gastric emptying. Wright et al. observed that epidural administration of 10 mL of 0.375% bupivacaine with fentanyl 100 µg caused a modest prolongation of gastric emptying during labor when compared with epidural administration of bupivacaine alone. However, Kelly et al. found that intrathecal, but not epidural, fentanyl delayed gastric emptying.

In summary, the preponderance of evidence suggests that (1) administration of an opioid during labor increases the likelihood of delayed gastric emptying during the early postpartum period; (2) gastric emptying of solids is delayed during labor and in the immediate postpartum period in all parturients; and (3) gastric emptying of clear liquids is probably not delayed unless parenteral opioids were administered.

Gastric Volume and pH

There is little evidence that postpartum women are at greater risk for sequelae if aspiration occurs than patients undergoing elective surgery, based solely on pregnancy-induced changes in gastric pH and volume. The conventional wisdom is that a gastric volume of more than 25 mL and a gastric pH of less than 2.5 are risk factors for aspiration pneumonitis. Coté noted that this dogma was derived from unpublished animal studies and that it assumes that every milliliter of gastric fluid is directed into the trachea. A marked disparity exists between the incidence of patients labeled “at risk” and the incidence of patients with clinically significant aspiration pneumonitis.

Blouw et al. measured gastric volume and pH in nonpregnant women undergoing gynecologic surgery and postpartum women 9 to 42 hours after delivery. They found no significant difference between the groups. Approximately 75% of women in both groups had a gastric pH of less than 2.5. When the combination of volume and pH was used to determine the risk for aspiration, 64% of the control patients but only 33% of postpartum patients were at risk. The researchers concluded that 8 hours after delivery, postpartum patients are not at greater risk than nonpregnant patients undergoing elective surgery. They did not examine patients earlier than 8 hours after delivery. In addition, they observed that a large number of patients in both groups are at risk based on their gastric volumes and pH.

James et al. attempted to determine the “safe” interval after delivery. They compared gastric pH and gastric volume in postpartum women 1 to 8 hours, 9 to 23 hours, and 24 to 45 hours after delivery with a control group of nonpregnant women undergoing elective surgery. There were no significant differences in either parameter between the group of patients undergoing elective surgery and any of the postpartum groups ( Table 25.1 ). Approximately 60% of all patients were considered “at risk” for aspiration pneumonitis. The investigators concluded that there was no difference in the risk for sequelae if aspiration should occur, but they speculated that hormonal changes or mechanical factors might make aspiration more likely during the postpartum period.

TABLE 25.1

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