Preterm Labor and Cerclage

What the Anesthesiologist Should Know before the Operative Procedure

Preterm labor is defined as regular painful contractions resulting in cervical change prior to 37 weeks’ gestation. A preterm infant is one born between 20 and 37 weeks’ gestation, with those born prior to 24 weeks or with a birth weight less than 750 grams having significantly worse mortality rates. It is important to know the cause of the preterm labor prior to providing anesthesia for women with preterm labor for vaginal delivery, cesarean delivery or cerclage placement. Most of the time, the cause will be unknown.

But in some cases abnormal uterine or cervical anatomy, trauma, abdominal surgery during the pregnancy, systemic illness, obesity, tobacco or illicit drug use, infection, bleeding, multiple gestations, abnormal fetal placentation, preterm premature rupture of membranes, or polyhydramnios may be the cause of the preterm labor. Such comorbidities may affect one’s anesthetic. Infection may be one of the most common factors in premature labor. Chorioamnionitis and acute pyelonephritis can lead to preterm labor as well as bacteremia and sepsis which can influence one’s anesthetic options. In order to halt preterm labor or to simply delay delivery while antenatal corticosteroid therapy is administered, tocolytic therapy may be administered. Tocolytic therapy includes calcium channel blocking agents, beta-adrenergic receptor agonists, magnesium sulfate, and cyclooxygenase inhibitors. These agents can have significant interactions with anesthesia.

Patients at risk of preterm labor or who have cervical change noted can have a prophylactic, therapeutic, or emergent transvaginal cerclage placement. Spinal, epidural, or general anesthesia may be administered for cerclage placement. The degree of dilation and the presence of bulging membranes may affect one’s anesthetic choice.

1. What is the urgency of the surgery?

What is the risk of delay in order to obtain additional preoperative information?

Delaying an emergent cesarean delivery when the obstetric provider believes that an immediate threat to the life of a fetus or mother may be present can be fatal for the mother, the fetus, or both. Therefore, do not delay an emergency cesarean delivery for laboratory values. If the obstetrician is highly suspicious of preeclampsia and there is no time to check laboratory values, or infection and there is no time to administer antibiotics, some anesthesiologists may prefer to proceed with general anesthesia. If the parturient has had no bleeding problems, and is afebrile, others may be comfortable proceeding with a neuraixal anesthetic. General anesthesia may also be necessary because there simply may be no time to establish neuraxial anesthesia.

In the case of an emergent transvaginal cerclage placement, it would be rare for a full work-up not to have been performed by the obstetricians. The obstetrician would need to be sure that the cervical changes are not a result of preterm labor (regular contractions actively changing the cervix) due to chorioamnionitis or placental abruption as these are contraindications to cerclage placement.

Emergent:Tell the User the issues related to emergent surgery Emergent or urgent cesarean delivery can be indicated in preterm labor just as it can in term labor because of placental abruption, uterine rupture, cord prolapse, or advanced dilation with breech presentation to name a few. In the emergent cases in which general anesthesia is necessary, it is important to note that the preterm infant may be exquisitely sensitive to the anesthetic agents transferred through the placenta. However, it may still be more important to secure adequate surgical conditions for cesarean by inducing a general anesthetic.

Urgent: Emergent or urgent cesarean delivery can be indicated in preterm labor just as it can in term labor. If there is time to perform a neuraxial technique and there are no contraindications, this is generally preferable to a general anesthetic. If chorioamnionitis or other infection is the cause the preterm labor, treatment with antibiotics prior to instrumentation of the neuraxis is generally recommended. Urgent cerclage placements, also termed “emergent” or “rescue” cerclage can be performed for patients that are already undergoing cervical change and may have bulging of membranes. Here, the greatest risk for the surgeon during the procedure is rupture of membranes. In order to replace the bulging fetal membranes back into the uterus, the obstetrician may request administration of a tocolytic agent or a general anesthetic with administration of a volatile anesthetic agent. Other techniques include Trendelenberg positioning, filling of the bladder with sterile saline, and placement of an inflated Foley catheter balloon in the cervix to push the membranes up and prevent traumatizing the membranes.

Elective: An elective cesarean delivery may be performed preterm for obstetric indications such as high-order multiple gestations, maternal illness, or preterm premature rupture of membranes to name a few. The anesthetic care of the mother in such cases is largely unchanged from a term cesarean delivery. The care of the neonate will be affected and ensuring adequate pediatric support is important in all preterm births. Elective cerclage placement may be transvaginal or transabdominal. Patients at high risk of cervical incompetence may receive prophylactic cerclage placement. These are typically done between 12 to 18 weeks of gestation, although transabdominal prophylactic cerclages may be placed prior to pregnancy. If a patient with a cerclage in place goes into labor, a transvaginal cerclage needs to be cut in order to facilitate delivery. In the case of an abdominal cerclage, cesarean delivery may be indicated.

2. Preoperative evaluation

Infection: Assess for fever, hypotension, tachycardia, severe abdominal pain, or flank pain. Labs may show elevated inflammatory markers or white blood cells. An amniocentesis or urine sample may have been assessed. If chorioamnionitis or concern for bacteremia is present, strong consideration should be given to antibiotic treatment prior to neuraxial instrumentation.

Side effects from tocolytic therapy: Pulmonary edema, tachycardia, hypotension, hyperglycemia, and hypo- or hyperkalemia can all be present if the patient is on tocolytic therapy. Multiple tocolytic agents increase the likelihood of pulmonary edema.

Illicit drug use: Because it is a risk factor for preterm labor, many institutions routinely screen women in preterm labor upon arrival to the hospital, and later their neonates’ first stool for illicit substances. Because discovery of drug use may influence whether their baby leaves the hospital with them, a woman may be more motivated to cover up her drug use. Cocaine and methamphetamine use can significantly affect a patient’s responses to anesthesia and stress.

Multiple gestations, polyhydramnios, fetal abnormalities, fetal demise, abnormal fetal placentation, and abdominal trauma can all lead to preterm labor. Ultrasound results and a thorough history from the patient can ascertain this information.

Medically unstable conditions warranting further evaluation include infection untreated with antibiotics or, infection treated with antibiotics with the patient still displaying fever and hypotension or tachycardia. Also, pulmonary edema that is requiring increasing oxygen therapy.

Delaying surgery may be indicated if delaying an emergent cesarean delivery when the obstetric provider believes that an immediate threat to the life of a fetus or mother may be present can be fatal for the mother, the fetus, or both. Therefore, do not delay an emergency cesarean delivery. If an immediate threat to the life or well-being of the mother or fetus is not present then delaying the surgery of a patient with suspected infection such as chorioamnionitis until antibiotics are administered may be prudent to potentially decrease the risk of meningitis or epidural abscess should neuraxial anesthesia be pursued. This may be especially important if the patient displays signs and symptoms of bacteremia.

3. What are the implications of co-existing disease on perioperative care?

b. Cardiovascular system

Acute/unstable conditions:Hypotension and tachycardia warrant a work-up for infectious causes of the preterm labor. If infection is suspected, antibiotics should be administered prior to neuraxial instrumentation. Hypertension may warrant a work-up for preeclampsia with repeated blood pressure checks and assessment of urine protein. If preeclampsia is present, then initiating antihypertensive therapy can reduce the patient’s risk of cerebral hemorrhage, and initiating magnesium therapy can reduce the patient’s risk of seizure. Thrombocytopenia associated with preeclampsia may direct an anesthesiologist away from neuraxial instrumentation.

Baseline coronary artery disease or cardiac dysfunction – Goals of management: Occasionally, parturients have congenital or acquired heart disease such as valvular disease or peripartum cardiomyopathy. Patients with a history of arrhythmia, cardiac valvular disease, or especially hypertrophic obstructive cardiomyopathy could have significant decompensation from tocolysis, especially if beta adrenergic receptor agonists are used.

Perioperative evaluation-:Evaluation for significant cardiac disease in pregnancy involves a obtaining a history from the patient focused on shortness of breath, significant exercise intolerance, chest pain or fainting spells; performing a physical exam; and subsequently directing testing such as electrocardiogram and echocardiogram from the results of the history and physical.

Perioperative risk reduction strategies: The knowledge that a patient has significant cardiac disease such as an arrhythmia or peripartum cardiomyopathy may change an anesthesiologist’s monitoring recommendations for vaginal or surgical delivery. The type of anesthesia, the fluid management, and even the level of postpartum care can be directed by this information. Informing the entire perinatal team of any contraindications to beta-mimetic tocolytic therapy is also important.

c. Pulmonary

Perioperative evaluation: Simply asking a patient if she has a history of asthma is typically adequate for evaluation.

Perioperative risk reduction strategies: Uterotonic medications are occasionally necessary after preterm birth to treat uterine atony. The presence of asthma alerts the anesthesiologist to avoid Hemabate (prostaglandin F2-alpha) because this agent can cause bronchial constriction in asthmatic patients.

d. Renal-GI:

Perioperative evaluation: In preterm labor, no specific renal testing needs to be considered unless pre-eclampsia is present, in which case a creatinine level should be obtained. If the parturient reports gastroesophageal reflux disease, they may be at increased risk of aspitation.

Perioperative risk reduction strategies: To prevent reflux of gastric contents into the lungs, most anesthesiologists employ aspiration prophylaxis for parturients going to the operating room. Oral sodium citrate, intravenous metoclopramide, H2 receptor blocking medications and rapid sequence intubation techniques are examples of medications and techniques used to reduce the risk of aspiration for parturients.

e. Neurologic:

Acute issues: Unless preeclampsia or eclampsia is present, patients with preterm labor have no greater neurologic concerns than do women with singleton pregnancies.

Chronic disease:Unless preeclampsia or eclampsia is present, patients with preterm labor have no greater neurologic concerns than do women with singleton pregnancies. Prior to all neuraxial techniques, it is important to obtain a history of any neurologic dysfunction or prior surgeries of the lumbar spine.

f. Endocrine:

If gestational diabetes is present, obstetricians will closely follow blood glucose levels in parturients in order to minimize neonatal hypoglycemia after birth.

g. Additional systems/conditions which may be of concern in a patient undergoing this procedure and are relevant for the anesthetic plan (eg. musculoskeletal in orthopedic procedures, hematologic in a cancer patient)

N/A

4. What are the patient's medications and how should they be managed in the perioperative period?

N/A

h. Are there medications commonly seen in patients undergoing this procedure and for which should there be greater concern?

Tocolytic therapy may be used to treat preterm labor. Tocolytic agents include calcium channel blocking agents (e.g., nifedipine), beta-adrenergic receptor agonists (e.g., terbutaline or ritodrine), magnesium sulfate and cyclooxygenase inhibitors (e.g., indomethacin). Side effects of beta-adrenergic receptor agonists include hypotension, tachycardia, cardiac arrhythmias (specifically supraventricular tachycardia), pulmonary edema, hyperglycemia, hypokalemia, and increased fetal heart rate as a result of placental transfer. Although nifedipine has fewer side effects, hypotension, headache, nausea, flushing and dizziness have been reported. Magnesium sulfate also has fewer cardiovascular side effects than beta adrenergic receptor agonists, but hypotension, tachycardia, pulmonary edema, and sedation can occur. Magnesium therapy must be monitored closely in patients with renal failure as it is eliminated entirely by the kidney. Magnesium toxicity can result in respiratory arrest, cardiac arrest, and death. Magnesium toxicity is treated with calcium gluconate or calcium chloride. Magnesium also potentiates the effect of nondepolarizing muscle relaxants. In addition to tocolytic therapy, magnesium may also be used as a bolus and infusion prior to delivery for fetal neuroprotection.

Antenatal corticosteroid therapy for fetal lung maturity utilizes betamethasone or dexamethasone. These agents can cause maternal hyperglycemia. Chronic medications to control blood glucose levels should be continued through labor and cesarean delivery with maternal glucose levels followed closely.

Anticoagulant medications should be noted by the anesthesia provider, and the performance of neuraxial anesthesia should follow the American Society of Regional Anesthesia guidelines as closely as possible.

If patients are on cardiac medications for chronic hypertension or a history of arrhythmia, these should be continued throughout labor or cesarean delivery.

Medications that cause sedation in the mother will likely cause a similar effect in the neonate, and informing the neonatology team is important so they can provide appropriate care, especially in cases of mothers on high doses of opioids or benzodiazepines. Do not acutely withdraw a parturient from such chronic medications in order to decrease fetal exposure.

i. What should be recommended with regard to continuation of medications taken chronically?

Cardiac: Continue all antiarrhythmic and antihypertensive medications throughout labor or cesarean delivery.

Pulmonary: Typically asthma improves with pregnancy, but continuation of asthma inhalers or oral medications is appropriate throughout labor or prior to cesarean delivery.

Neurologic: Antiseizure medications should be continued throughout labor or surgery.

Antiplatelet: Anticoagulant medications should be noted and the performance of neuraxial anesthesia should follow the American Society of Regional Anesthesia guidelines as closely as possible. (. ASRA guidelines http://www.asra.com/publications-anticoagulation-3rd-edition-2010.php)

Psychiatric: Continue all chronic antipsychotic, opioid, and benzodiazepine medications throughout labor or cesarean delivery and inform the neonatology team. Do not acutely withdraw a parturient prior to the birth.

j. How To modify care for patients with known allergies –

N/A

k. Latex allergy- If the patient has a sensitivity to latex (eg. rash from gloves, underwear, etc.) versus anaphylactic reaction, prepare the operating room with latex-free products.

N/A

l. Does the patient have any antibiotic allergies? (common antibiotic allergies and alternative antibiotics)

N/A

m. Does the patient have a history of allergy to anesthesia?

Malignant hyperthermia (MH)

Documented: Avoid all trigger agents such as succinylcholine and inhalational agents:

Proposed general anesthetic plan:
Ensure MH cart available: [MH protocol]
Family history or risk factors for MH:

Local anesthetics/muscle relaxants

Local anesthetic or opioid allergies may change a neuraxial anesthesia plan. For example, if a patient reports a morphine allergy, intrathecal morphine could be avoided for cesarean delivery and postoperative pain control could be managed with patient controlled intravenous analgesia with an alternative opioid such as fentanyl or hydromorphone. Also, if an amide local anesthetic allergy is reported, using an ester local anesthetic such as 2-chloroprocaine is appropriate, or alternatively a general anesthetic could be performed for cesarean delivery.

5. What laboratory tests should be obtained and has everything been reviewed?

Hemoglobin levels: Although red cell mass increases in pregnancy, plasma volume increases even more creating a “relative” anemia with a parturient’s hemoglobin typically being around 11.7.

Electrolytes: Magnesium levels for patients on magnesium therapy with renal insufficiency are important. Hypokalemia may be present in patients who are on beta adrenergic receptor agonists.

Coagulation panel: Patients with preeclampsia should have a platelet count and arguably a coagulation profile. If the platelet count is abnormal, if the preeclampsia is severe, placental abruption is suspected, or subcutaneous unfractionated heparin has been administered, a coagulation profile including PT, INR, APTT, and fibrinogen are indicated.

Imaging: Include stress tests, renal imaging tests, etc. Ultrasound imaging of the preterm fetus can assess the position and well-being of the fetus (via a biophysical profile). Abnormal placentation can sometimes also be identified by ultrasonography, alerting the anesthesiologist to the risk of massive blood loss.

Intraoperative Management: What are the options for anesthetic management and how to determine the best technique?

For preterm labor and vaginal delivery, regional anesthesia with an epidural or a combined spinal epidural can provide excellent analgesia. For preterm cesarean delivery, after aspiration prophylaxis, intravenous catheter placement, and routine noninvasive monitoring placement, a regional or a general anesthetic are options. The regional technique is generally preferred, allowing the mother to be awake for the birth of her baby, resulting in lesser exposure of the fetus to anesthetic agents, avoiding the necessity of airway manipulation, and providing better postoperative analgesia. Left uterine displacement should be utilized at all times until after delivery.

For a cerclage procedure, after aspiration prophylaxis, intravenous catheter placement, and routine noninvasive monitoring placement, a regional or a general anesthetic are options. Whether the cervix is dilated and the membranes exposed will influence the choice of anesthetic. Immobility during the procedure is key to avoid damaging the membranes during placement of the cerclage. Regional anesthesia with a spinal is the preferred technique for a prophylactic cerclage. If the membranes are exposed, the choice of regional versus general anesthesia is less clear. General anesthesia with volatile agents allows for relaxation of the uterus and decreased intrauterine pressure, facilitating replacement of the membranes back into the uterus and placement of the cerclage. However, if the patient coughs from the endotracheal tube or experiences vomiting after the anesthetic, this can raise intra-uterine pressure.

Regional anesthesia decreases the likelihood of endotracheal tube induced coughing or postoperative vomiting, but could, with the flexion of the spine required for placement, transiently raise intrauterine pressure. Regional anesthesia does not provide the uterine relaxation provided by volatile agents, although other tocolytic agents can be used. Therefore, discussion of the risks and benefits of each technique with both the patient and surgeon is necessary. Of note, this author generally prefers regional anesthesia for both prophylactic and emergent cerclage procedures. If regional anesthesia is chosen for a cerclage, blockade of T10 through S4 is necessary with a spinal or epidural technique. Left uterine displacement positioning is important if the gestation is beyond 18 to 20 weeks.

Consideration should be given to fetal heart rate monitoring although the obstetricians will check fetal heart tones by ultrasound before and after the procedure. If the patient is undergoing an emergent cerclage with exposed membranes, the obstetric team may desire Trendelenberg positioning. In these scenarios, hyperbaric intrathecal medications should be avoided and isobaric utilized.

a. Regional anesthesia

For labor analgesia in the preterm mother, a lumbar epidural may be placed and subsequently bolused with 10-20 mL of dilute bupivacaine (typically 0.0625%-0.125%) with fentanyl (typically 2 mcg/mL) and then maintained at 5-10 mL per hour via a continuous infusion pump with a patient controlled epidural analgesia option (typically around 5 mL of the solution upon patient demand every 5-15 minutes). A traditional epinephrine-containing test dose is often administered (eg. 3 mL of 1.5% lidocaine with 1:200,000 epinephrine) to check for intrathecal or intravascular placement of the epidural catheter. The benefits of this analgesic technique include excellent patient comfort during labor, as well as a vehicle for securing neuraxial anesthesia should the need for cesarean delivery arise.

Regional anesthesia for cesarean delivery for preterm labor includes the epidural option or a spinal anesthetic which is often performed with hyperbaric bupivacaine (e.g. 1.5 mL of 0.75% bupivacaine with dextrose) with fentanyl (e.g. 10-25 mcg) and morphine (e.g., 0.1-0.3 mcg). An alternative is a combined spinal-epidural technique which involves placing the spinal anesthetic and threading an epidural catheter as well, either for labor or if the surgery may last longer than the duration of the spinal.

Regional anesthesia can be used for cerclage procedures. A spinal anesthetic achieving above a T10 level with, for example, 1.0-1.2 mL of 0.75% bupivacaine or 50 mg spinal lidocaine are options, with lidocaine providing a shorter block time and faster recovery but greater potential for transient neurologic symptoms. Fentanyl 10-25 mcg should also be added. Another option for regional anesthesia is a midlumbar epidural incrementally loaded with 10 to 15 mL of 2% lidocaine with 100 mcg of fentanyl to achieve a T8 through S4 sensory block, although achieving sacral segment block is less reliable with an epidural anesthetic.

Neuraxial

Benefits: For labor, the benefit is deceased pain of childbirth for the parturient. For a cesarean delivery, the mother gets to be awake for the birth of her baby. There is typically no need for maternal airway management. The fetus is not exposed to general anesthetic agents. The obstetricians do not feel the urgency to proceed rapidly from induction to delivery in order to reduce anesthetic exposure for the fetus.

For a prophylactic cerclage, the benefits of neuraxial anesthesia include avoiding airway manipulation, immobility, avoiding exposure to general anesthesia for the fetus, and decreased postoperative nausea and vomiting. For an emergent cerclage, the benefits include decreasing the risk of raising intrauterine pressure with coughing as a result of airway manipulation or vomiting as a result of postoperative nausea.

Drawbacks: There are few drawbacks for regional anesthesia labor analgesia or cesarean anesthesia or prophylactic cerclage anesthesia. The typical risks for bleeding, infection, nerve damage, postdural puncture headache, and, for epidural placement, local anesthetic toxicity should be discussed with the patient. For emergent cerclage, a drawback includes that no volatile anesthetic will be present to relax the smooth muscle of the uterus, although other tocolytic agents can be used. Also, the positioning required for a neuraxial technique may raise intrauterine pressure. The rare risk for bleeding, infection, or nerve damage is present with neuraxial instrumentation.

These risks may be greater in patients with HELLP syndrome, bleeding diatheses, or who are on antithrombotic medications such as low molecular weight heparin, unfractionated heparin, Coumadin, or Plavix. The latter two are rarely used in pregnancy in the United States. Risk of infection may be increased in patients with a systemic infection, such as untreated chorioamnionitis, and therefore treatment with antibiotics is recommended prior to instrumentation of the neuraxis. Patients with preexisting nerve damage, spinal stenosis, or hardware about the spine may be at increased risk of neurologic complications, although all risks and benefits need to be weighed, and despite these conditions, neuraxial is often chosen.

Local anesthetic toxicity is a possibility with epidural anesthesia. Mothers may feel discomfort during cesarean delivery, more so under epidural than spinal anesthesia. Hypotension after initiation of neuraxial anesthesia can lead to nausea, vomiting, and fetal distress. This is easily treated with left uterine displacement positioning, co-loading with crystalloid intravenous solution, and vasopressors such as an intravenous phenylephrine drip or boluses of ephedrine and/or phenylephrine.

Peripheral nerve block

Not applicable

b. General Anesthesia

Benefits: For a cerclage procedure, general anesthetic with volatile agents allows for relaxation of the uterus and decreased intrauterine pressure, facilitating replacement of the membranes back into the uterus and placement of the cerclage. For a cesarean delivery, general anesthesia mitigates the risk of neuraxial bleeding in patients with bleeding diatheses. In cases in which massive hemorrhage or cesarean hysterectomy is anticipated, the patient is already under general anesthesia.

Drawbacks: For a cerclage, if the patient coughs from the endotracheal tube under light anesthesia or experiences vomiting after the anesthetic, intrauterine pressure can be increased. Drawbacks for general anesthesia for a cesarean delivery include the following: The mother is asleep for the birth of her baby. The fetus is exposed to general anesthetic agents. The obstetricians feel additional pressure to operate rapidly to minimize exposure of the fetus to the anesthetic agents. Previously it was believed that general anesthesia put a mother at greater risk of mortality than regional anesthesia because of the risk of loss of airway at induction; however, more recent data indicate that this may not be the case.

Other issues: Postoperative nausea and vomiting can lead to increased intrauterine pressure. General anesthesia for cesarean delivery is a procedure with a high risk of intraoperative awareness.

Airway concerns: Parturients carry greater airway concerns than nonpregnant patients including decreased apnea time (decreased functional residual capacity and increased oxygen consumption), increased risk for aspiration (decreased lower esophageal tone and a displaced stomach), increased airway edema, increased risk of airway bleeding (especially nasal bleeding with manipulation). Further, the need to obtain an airway rapidly in the event of an emergency cesarean delivery may be more likely in the parturient with preterm gestations. Rapid sequence intubation with cricoid pressure is recommended for parturients undergoing general anesthesia for cesarean delivery: this is especially important for patients in labor or those who are not appropriately fasted.

Monitored Anesthesia Care

This author does not recommend performing an anesthetic for a cerclage procedure under monitored anesthesia care because of the risk of patient discomfort and movement.

6. What is the author's preferred method of anesthesia technique and why?

What prophylactic antibiotics should be administered?

No antibiotics are routinely given for vaginal delivery or cerclage. Cefazolin 1-2 grams are given prior to cesarean delivery.

What can I do intraoperatively to assist the surgeon and optimize patient care?

If uterine relaxation is needed during cerclage placement, uterine relaxants such as nitroglycerin (sublingual spray or 50-500 mcg IV), terbutaline (0.25 mg IV or subcutaneously), or increased volatile anesthetic agents (if under general anesthesia) could be administered.

What are the most common intraoperative complications and how can they be avoided/treated?

Hemorrhage is a possibility with any delivery, with the most common cause uterine atony. Uterotonic agents such as oxytocin, ergot alkaloids (e.g., Methergine), prostaglandin F2 alpha (Hemabate), and misprostol (Cytotec) are treatment options. Uterine inversion or severe shoulder dystocia may need to be treated with uterine relaxants such as nitroglycerin, terbutaline, or volatile anesthetic agents if intubated. The most common complication of an emergent cerclage is rupture of membranes during the procedure. Avoidance of this can occur by limiting movement, coughing, vomiting and perhaps maintenance of Trendelenberg positioning. Amniotic fluid embolism is a rare but deadly complication in the peripartum period. Little is known as to what can potentially prevent the complication, but supportive care including cardiopulmonary resusc0itation, advanced cardiac life support, and even ECMO or cardiopulmonary bypass are treatment options.

Complications

Cardiac: Tocolytic agents can cause tachycardia and hypotension.

Pulmonary: Tocolytic agents can cause pulmonary edema. Pulmonary edema can be treated with supportive therapy as necessary to maintain oxygenation and ventilation (diuresis, CPAP, BIPAP, or intubation with mechanical ventilation). Intravenous furosemide, careful fluid management, and discontinuation of multiple tocolytic agents can also assist in treatment.

a. Neurologic

Postdural puncture headache can occur with neuraxial anesthesia.

b. If the patient is intubated, are there any special criteria for extubation?

Recent data indicate that postoperative airway loss is a cause of anesthesia-related maternal mortality. Waiting to extubate until standard extubation criteria have been met and appropriate monitoring in transport and in the postoperative area are important for patient safety. After cerclage procedures, balance this with the need to avoid coughing on the endotracheal tube by using narcotics or intravenous lidocaine to suppress the cough reflex.

c. Postoperative management

What analgesic modalities can I implement?

Unless significant vaginal trauma has occurred, analgesia other than ibuprofen are not necessary after vaginal preterm delivery. After cesarean delivery, intrathecal long-acting opioid medications (e.g., 0.1-0.3 mg preservative-free morphine) can be administered at the time of a spinal anesthetic. Epidural long-acting opioid medications (e.g., 4 mg PF-morphine) can also be administered. Alternatively, an epidural infusion can continue into the postoperative period for analgesia. Typically, postprocedure pain is not significant after a cerclage procedure.

What level bed acuity is appropriate?

After preterm vaginal delivery, cesarean delivery or cerclage, L&D floor care is appropriate. Following cerclage, patients will need intermittent or continuous fetal monitoring.

What are common postoperative complications, and ways to prevent and treat them?

Parturients having a preterm vaginal delivery may be at increased risk of a prolonged third stage of labor or retained placenta, requiring a manual extraction for removal. Manual extraction of the placenta can be extremely painful. If a labor epidural is in place, bolusing it with a surgical concentration of local anesthetic to attain a T10 level (e.g., 10-15 mL of 2% lidocaine) can facilitate the procedure. If an epidural is not in place, a spinal anesthetic may be performed, or a general anesthetic could also be considered. Heavy sedation should be avoided in a laboring patient who may be at risk of aspiration.

After cesarean delivery, appropriate postoperative assessments for hypoventilation are important in patients who have been administered intrathecal long-acting opioids (e.g. PF-morphine) as well as patients that are on intravenous opioid patient controlled analgesia pumps. The ASA Guidelines for Prevention of Respiratory Depression after Neuraxial Opioids should be followed.

What's the Evidence?

“ACOG Committee on Obstetric Practice. Magnesium sulfate before anticipated preterm birth for neuroprotection”. Obstet Gynecol . vol. 115. 2010. pp. 669-71. (American College of Obstetricians & Gynecologists' guidelines on use of magnesium for fetal neuroprotection before anticipated preterm birth.)

Lyell, DJ, Pullen, K, Campbell, L, Ching, S, Druzin, ML, Chitkara, U, Burrs, D, Caughey, AB, El-Sayed, YY. “Magnesium sulfate compared with nifedipine for acute tocolysis of preterm labor, a randomized controlled trial”. Obstet Gynecol . vol. 110. 2007. pp. 61-7. (An RCT comparing the two most commonly used tocolytics that led to an effective oral tocolytic agent with fewer side effects than intravenous magnesium.)

Haas, DM, Imperiale, TF, Kirkpatrick, PR, Klein, RW, Zollinger, TW, Golichowski, AM. “Tocolytic therapy: a meta-analysis and decision analysis”. Obstet Gynecol . vol. 113. 2009. pp. 585-94. (This is a good overview of the available tocolytics and their risks and benefits from an obstetrician's point of view.)

Amin, SB, Ginkin, RA, Glantz, JC. “Metaanalysis of the effect of antenatal indomethacin on neonatal outcomes”. Am J Obstet Gynecol . vol. 197. 2007. pp. 486.e1-e10. (A good review of the potential adverse effects of this very effective tocolytic agent.)

Simhan, HN, Caritis, SN. “Prevention of preterm delivery”. N Engl J Med . vol. 357. 2007. pp. 477-87. (This is a good review article covering the limited things we can do to prevent preterm delivery.)

Phibbs, CS, Baker, LC, Caughey, AB, Danielsen, B, Schmitt, SK, Phibbs, RH. “Level and volume of neonatal intensive care and mortality in very-low birth-weight infants”. N Engl J Med . vol. 356. 2007. pp. 2165-75. (Busier NICUs have better outcomes.)

Horlocker, TT, Wedel, DJ, Rowlingson, JC. “Regional anesthesia in the patient receiving antithrombotic or thrombolytic therapy: American Society of Regional Anesthesia and Pain Medicine evidence-based guidelines (third edition)”. Reg Anesth Pain Med . vol. 35. 2010. pp. 64-101. (This is not necessarily related to preterm labor but relevant to provision of neuraxial analgesia or anesthesia for these parturients who may be on prophylactic anticoagulation.)

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