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Preoperative Evaluation/Patient Issues/Ambulatory surgery for pregnant patients

QUESTION:

Iwork at a free-standing surgery center across from a medical center. Recently, a surgeon wanted to schedule an I & D of a breast abscess on a pregnant patient scheduled for an elective c-section in a few days. I was hesitant because of the risk of inducing labor, but more importantly, fetal distress. Is it wise to do this at a free-standing ASC? Should continuous fetal monitoring be utilized in this situation? If monitoring is used, is it incumbent to have the availability for an immediate c-section should problems arise? Are there any limitations on what procedures and when they can be performed as an out-patient on the pregnant patient?

-- From Steven Spiro, M.D., Mission Hills, CA

REPLY:

I think your hesitation about doing this case at your center was understandable. The risk of inducing labor is fairly high in the third trimester, for pelvic and uterine surgery, due to close proximity to the uterus. Even though breast surgery is a little remote from the uterus - the surgical procedure, site of surgery, and the patient's underlying condition have been shown to be associated with a higher incidence of abortion in the first trimester, labor in the third trimester, IUGR, and perinatal mortality.

It is probably not a good idea to operate on a pregnant patient, in the third trimester, at an ambulatory facility without obstetric back-up. Ideally, a labor and delivery nurse, midwife, or an obstetrician should be available intraoperatively to monitor fetal heart tones (FHTs) and uterine contractions. Normally, I & D of a breast abscess is a quick procedure and establishment of FHT monitoring/uterine contraction monitoring may take some time. Therefore, such monitoring may not be practical in this setting. However, as a general guideline, such monitoring should be instituted in all kinds of surgery, if technically possible. Post-operatively, the recommendation is to monitor for FHTs and uterine contractions for at least 24 hours.

Yes, FHTs should be monitored continuously intraoperatively, if technically feasible, and postoperatively.

Obviously, monitoring and any detection of fetal decelerations (late or variable) will necessitate immediate delivery. Facility and personnel to institute immediate delivery of the baby should be available on site. It may not be wise to rush the patient across the street to the medical center for delivery of a compromised fetus for both, safety issues and medico-legal reasons.

Each medical facility should adhere to their institutional regulations regarding surgery for the pregnant patient. Below are some general guidelines, modified from the references mentioned below and adapted for the ambulatory setting:

1. Avoid surgery during pregnancy, if possible.
2. Avoid surgery during first trimester (organogenesis) - high risk for abortion and congenital anomalies. Postpone surgery until second trimester, if possible.
3. Avoid surgery during third trimester - high risk for inducing labor. Postpone surgery until postpartum period, if possible.
4. Preoperative evaluation of patient by obstetrician.
5. Preoperative counselling of patient by anesthesiologist and obstetrician, especially regarding possible effects on fetus from agents and techniques used.
6. A thorough, preoperative airway examination by the anesthesia care team - risk of difficult tracheal intubation is almost 8 times higher in the pregnant patient. A difficult airway cart must be readily stocked and available on site.
7. Prophylaxis against pulmonary aspiration - use of non-particulate antacid, H2 antagonist, and metoclopramide (barring, no contraindications such as bowel surgery).
8. Avoid general anesthesia. Use regional or local anesthesia, if possible - paracervical blocks are contraindicated in a patient with a viable fetus.
9. If general anesthesia has to be used, avoid high concentration of nitrous oxide for a prolonged period of time. It may reduce uterine blood flow (animal studies). It is recommended to add a volatile agent to offset the uterine vasospasm associated with nitrous oxide. The volatile agent also reduces myometrial irritability and may prevent premature induction of labor. Use preoxygenation, rapid sequence induction/intubation, and cricoid pressure.
10. Consider tocolysis, especially in second trimester and third trimester. All tocolytics have cardiovascular adverse effects which should be weighed against the possible benefits of preventing premature labor.
11. Left uterine displacement should be maintained perioperatively (preop, intraop, and postop) in second and third trimester.
12. Monitor for FHTs and uterine contractions intraoperatively, if technically feasible, and postoperatively under proper supervision (labor and delivery nurse, midwife, or obstetrician). Transvaginal probes are available to allow monitoring during abdominal or pelvic surgery. Neuraxial analgesia may mask the pain associated with uterine contractions - therefore, monitoring uterine contractions post-operatively is essential. If necessary, tocolysis can be instituted expeditiously.
13. Maintain homeostasis (normal blood glucose, normal oxygenation, normal blood pressure, and normal carbon dioxide).
14. Document FHTs preoperatively, intraoperatively - if possible, and post-operatively.
15. Have an obstetric back-up (equipment and personnel) on site for monitoring and facilitating delivery - vaginal or cesarean.
16. Prophylax against venous thrombosis.

Good references for this topic include:

1. Nonobstetric surgery during pregnancy by Sheila Cohen, M. D. in David Chestnut's Obstetric Anesthesia, Principles and Practice, 2nd edition.
2. Anesthesia for the obstetric patient for non-obstetric surgery by Joy Hawkins, M. D. in IARS Review Course Lectures, 1997 series.

-- From Ashu Wali, M.D., F.F.A.R.C.S.I., Houston, TX

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