1. Abdominal mass in a pregnancy
-Case presentation
By R3陳世昱

2. General & Past History 35 y/o female
Denied past history of systemic disease or op
No contributable family/drug/allergy history
H: 160cm, W: 54kg
Pregnancy (6wks ; LMP:2003/3/17) with progressive abdominal distention

3. Present Illness (summary 1)
RLQ pain 9 yrs ago
1998/10, TAS:7x6cm right pelvic mass, suspect endometriosis (which regressed 3 months later spontaneously)
1999/8, TAS:12x8x8cm heterogeneous mass over uterine fundus and ~30ml ascites; MRI revealed a 1.5cm ROV cyst, and CA-125:WNL
No GI or URO S/S nor ↑CA-125, so OPD f/u was suggested and kept.

4. Present Illness (summary 2)
Missed MC period in 2003/4, and urine pregnancy test showed positive result
Progressive abdominal distension soon later
4/23 OPD :
TAS: >25x20cm pelvic mass c lacunar pattern and solid component and moderate ascites
↑CA-125: 578μ/ml
R/O ovarian malignancy → surgical evaluation

6. 麻醉紀錄

8. Non-obstetric Surgery during Pregnancy
Discussion :
Non-obstetric Surgery during Pregnancy

9. Incidence About 0.3~2% of deliveries Most common: appendectomy
Almost every type of surgical procedure

10. Basic objectives Maternal safety Avoidance of teratogenic drugs
Avoidance of intrauterine fetal asphyxia
Prevention of preterm labor

11. Monitoring Routine monitors
Fetal heart rate monitoring: Doppler apparatus such as tocodynamometer(≥umbilicus) after 16wks of pregnancy.
An obstetrician is present throughout operation
Elevations of maternal BP may treat fetal bradycardia, and inhalation agents may diminish the amplitude of uterine contractions.

12. Physiologic Changes

13. Teratogenic drugs(1)
Teratogen: a substance produces an increase in incidence of a particular defect that can’t be attributed to chance. A sufficient dose at a critical point in development is needed.
Critical point in human: during organogenesis, which extends from 15 days’ to approximately 60 days’ gestational age.
CNS does not fully develop until after birth, so critical time for this system could be through the entire gestation.

14. Teratogenic drugs(2)
Almost every anesthetic or drug has been found to be a teratogen in an animal model (in greatly exceeded doses than used clinically), but no anesthetic drug has been documented to be a teratogen in humans.
BZD, Barbiturates, Ketamine, Propofol and Etomidate are known teratogens in animals, but have never been demonstrated in humans.
Narcotics: CNS abnormalities in hamster, but never been reproduced in humans. Low-birth-weight babies has been associated with chronic administration, but no congenital defects.

15. Teratogenic drugs(3)
Muscle relaxants: cause skeletal abnormalities in the chick embryo, but never been reproduced in the human fetus; do NOT cross the placenta
Nitrous oxide: ↓Vit.B12→↓methionine synthetase→↓DNA synthesis, but has been used in hundreds of anesthetics s problems.
Halogenated agents: beneficial to fetus by  uterine relaxation and  increasing uterine blood flow, and so far found it safe in clinical doses.

16. Avoidance of intrauterine fetal asphyxia
Maintain maternal PaO2:
Relative difficult airway
↓FRC→↑rate of desaturation
Prevent high leveltoxic local anesthetics toxicity andoversedation in regional anesthesia
Adequate maternal PaCO2:
Hypocapnia:
By excessive positive ventilation→↑intrathoracic pressure→↓venous return→↓uterine blood flow
Maternal alkalosis→vasoconstriction & left shift of O2-Hb dis. curve
Hypercapnia: fetal acidosis
Maintain uterine blood flow:
Perfusion pressure: prevent hypotension, aortocaval compression, hemorrhage and “heavy” regional anesthesia
Vasoconstriction: prevent α-agonist, ↓PaCO2 & ↑catecholamines (pain, insufficient anesthesia or so)

17. Prevent of Preterm Labor
The only factors correlated with preterm labor are the type and location of the procedure.
No study documents any correlation of anesthetic drug or technique with preterm labor
However, in theoretically, some anesthetic agents such as ketamine(>1mg/kg) and phenylephrine that can increase uterine tone should be avoid as possible.
The halogenated agents ↓uterine tone &↑uterine blood flow and may be beneficial in this aspect.

18. Recommendations of anesthetizing a pregnancy for Non-obstetric Surgery
Avoid surgery and anesthesia in the first trimester, if possible, without compromising maternal health.
Non-particulate antacid for aspiration pneumonitis prophylaxis after first trimester
Transport patient with left uterine displacement
Continuing fetal/uterus monitoring if possible
Regional anesthesia is recommended whenever possible (fluid preloading; fluid and/or ephedrine)

19. Recommendations of anesthetizing a pregnancy for Non-obstetric Surgery
General anesthesia:
Avoid hypotension with fluid preloading
Airway managements:
Pre-oxygenation with 100%O2
Induction : rapid-sequence with cricoid-pressure
Maintain adequate oxygenation(50% or higher) and normocarbia
Anesthetic agents:
Drug of Choice: with a long history and relative safety
Pentothal, morphine, fentanyl, meperidine,nitro-oxide
SCC,Atracurium, vecuronium, curare and pancuronium
Halogenated agents may be beneficial
Ketamine and α-agonist should be avoid
Antagonize muscle relaxant and extubate when fully awake and able to control airway reflexs

20. Thanks for Your attention!!