Obstetric Anesthesia Practice Questions

Q: A 22-year-old primigravid woman at term presents to the labor room with contractions every 2 minutes. Her prenatal course was unremarkable, and she takes no medications and has no known drug allergies. Examination reveals her cervix to be 6 cm dilated and 100% effaced, with the fetus at 0 station. The fetal heart rate has a baseline in the 150s and is reactive. The patient desires an epidural for pain relief. Which of the following should be given orally shortly before the epidural is placed?

Antacid. **Explanation:** The correct answer is **A. Antacid**. **Why Antacids are given:** Pregnant women are at a significantly increased risk of **aspiration pneumonitis (Mendelson Syndrome)** during labor. This is due to several physiological changes: increased intra-abdominal pressure from the gravid uterus, progesterone-mediated relaxation of the lower esophageal sphincter, and delayed gastric emptying. Before administering neuraxial anesthesia (like an epidural), it is standard practice to administer a non-particulate antacid (e.g., **Sodium Citrate**). The goal is to increase the pH of the gastric contents. If an emergency arises requiring general anesthesia or if the patient vomits and aspirates, a higher gastric pH ( >2.5) significantly reduces the risk of severe chemical pneumonitis. **Why other options are incorrect:** * **B. Antibiotic:** Routine prophylactic antibiotics are not indicated for the placement of an epidural. They are reserved for specific indications like Group B Strep (GBS) prophylaxis or prior to a Cesarean section. * **C. Aspirin:** Aspirin is an antiplatelet agent and is contraindicated immediately before neuraxial anesthesia due to the risk of an epidural hematoma. * **D. Clear liquid meal:** While clear liquids are often allowed in early labor, they do not provide the protective pH-neutralizing effect required before an anesthetic procedure. **NEET-PG High-Yield Pearls:** * **Mendelson Syndrome:** Defined as aspiration of gastric contents with a pH 25 ml (0.4 ml/kg). * **Non-particulate antacids** (Sodium Citrate) are preferred over particulate ones (Magnesium hydroxide) because they are less harmful if aspirated. * **Prokinetic agents** (Metoclopramide) may also be used to facilitate gastric emptying in laboring patients.

Q: For painless delivery using epidural anaesthesia, what dermatomal level of block is typically desired?

T10 - S5. To achieve effective labor analgesia (painless delivery), the anesthetic block must cover the pain pathways associated with both the first and second stages of labor. **1. Why T10 – S5 is correct:** * **First Stage of Labor:** Pain is primarily visceral, caused by uterine contractions and cervical dilation. These impulses travel via sympathetic afferents to the **T10 to L1** spinal segments. * **Second Stage of Labor:** Pain becomes somatic due to the stretching of the pelvic floor, vagina, and perineum as the fetus descends. these impulses travel via the pudendal nerve to the **S2 to S4** spinal segments. * Therefore, a comprehensive block from **T10 to S5** ensures coverage for both stages, providing relief from uterine contractions through to the delivery of the baby. **2. Why other options are incorrect:** * **T11 – L5:** This range is insufficient. It misses the upper dermatomes (T10) required for the first stage and, more importantly, lacks the sacral coverage (S2–S4) necessary for the second stage. * **T4 – S5:** This level is too high. A T4 level is typically the target for a **Cesarean Section** to prevent discomfort during peritoneal traction. For labor analgesia, this would cause unnecessary motor blockade and potential hypotension. * **L1 – S5:** This misses the T10–T12 segments, leaving the patient with significant pain during uterine contractions in the first stage. **Clinical Pearls for NEET-PG:** * **Gold Standard:** Epidural analgesia is the gold standard for labor pain relief. * **Concentration:** "Walking epidurals" use low-dose local anesthetics (e.g., 0.0625% Bupivacaine) combined with opioids (Fentanyl) to provide sensory block while sparing motor function. * **Complication:** The most common side effect of regional anesthesia in obstetrics is **maternal hypotension** due to sympathetic blockade.

Q: Regarding the use of halothane in obstetric surgery, which statement is true?

There is an increased risk of postpartum hemorrhage.. **Explanation:** **1. Why Option A is Correct:** Halothane, like other potent volatile anesthetic agents (Isoflurane, Sevoflurane), causes **dose-dependent relaxation of the uterine smooth muscle**. It inhibits the action of oxytocin on the myometrium, leading to uterine atony. In the context of obstetric surgery (like a Cesarean section), a relaxed uterus cannot contract effectively after placental delivery to compress the intramyometrial vessels. This failure of contraction significantly increases the risk of **Postpartum Hemorrhage (PPH)**. **2. Why Other Options are Incorrect:** * **Option B:** Halothane has a profound effect on uterine musculature; it is a potent tocolytic (uterine relaxant). * **Option C:** Halothane is generally **avoided** or used at very low concentrations (usually <0.5 MAC) in Cesarean sections specifically because of the risk of atony and hemorrhage. Modern practice prefers neuraxial anesthesia (Spinal/Epidural) or rapid sequence induction with low-dose volatile agents supplemented by nitrous oxide and opioids after delivery. **3. High-Yield Clinical Pearls for NEET-PG:** * **MAC and Uterus:** Volatile agents relax the uterus significantly at concentrations >0.5 MAC. At 1.5–2.0 MAC, the uterus becomes completely unresponsive to oxytocin. * **Clinical Utility:** While avoided in routine C-sections, the uterine-relaxing property of Halothane/Isoflurane is clinically useful in specific emergencies requiring intrauterine manipulation, such as **Breech extraction, Internal Podalic Version, or Manual Removal of a Retained Placenta.** * **Drug of Choice:** For routine General Anesthesia in obstetrics, **Sevoflurane** is often preferred over Halothane due to its faster induction/recovery and slightly less profound effect on uterine tone at low concentrations.

Question 1

A pregnant patient at full term has both mitral stenosis and mitral regurgitation. If the obstetrician plans to conduct a normal delivery, what would be the preferred method of analgesia?

Accepted Answer

Neuraxial analgesia

Answer

Parenteral opioids

Answer

General anesthesia

Answer

Inhalational analgesia

Question 2

A term gestation patient with critical aortic stenosis presents to labor, and her cervix is 6 cm dilated. Your approach to the treatment of this patient includes all except:

Accepted Answer

Restrict IV fluids to decrease cardiac preload.

Answer

Provide epidural analgesia.

Answer

Limit activity.

Answer

Perform pulmonary artery catheterization.

Question 3

A 22-year-old primigravid woman at term presents to the labor room with contractions every 2 minutes. Her prenatal course was unremarkable, and she takes no medications and has no known drug allergies. Examination reveals her cervix to be 6 cm dilated and 100% effaced, with the fetus at 0 station. The fetal heart rate has a baseline in the 150s and is reactive. The patient desires an epidural for pain relief. Which of the following should be given orally shortly before the epidural is placed?

Accepted Answer

Antacid

Answer

Antibiotic

Answer

Aspirin

Answer

Clear liquid meal

Question 4

Which of the following drugs is the vasopressor of choice in pregnancy?

Accepted Answer

Ephedrine

Answer

Phenylephrine

Answer

Methoxamine

Answer

Mephentermine

Question 5

Which of the following statements regarding neuraxial opioids for labor and delivery is true?

Accepted Answer

Systemic absorption is similar to intramuscular administration.

Answer

Opioids should never be used as a sole agent.

Answer

The most common side effect is fetal bradycardia.

Answer

Intrathecal morphine is associated with a quick peak in concentration and early onset maternal respiratory depression.

Question 6

For painless delivery using epidural anaesthesia, what dermatomal level of block is typically desired?

Accepted Answer

T10 - S5

Answer

T11 - L5

Answer

T4 - S5

Answer

L1 - S5

Question 7

Which of the following statements is NOT true regarding epidural anesthesia in pregnancy?

Accepted Answer

Associated with increased cardiac output.

Answer

Administered via the epidural space.

Answer

Leads to decreased venous return.

Answer

Can cause hypotension.

Question 8

High concentration of bupivacaine during labor is contraindicated due to which of the following?

Accepted Answer

Cardiotoxicity

Answer

Central nervous system depressant action

Answer

Central nervous system stimulant action

Answer

Hypersensitivity reaction

Question 9

Regarding the use of halothane in obstetric surgery, which statement is true?

Accepted Answer

There is an increased risk of postpartum hemorrhage.

Answer

It has no effect on uterine musculature.

Answer

It is best used in cesarean sections.

Answer

None of the above statements are true.

Question 10

During maintenance of a general inhaled anesthetic for urgent non-obstetric surgery, what difference would be expected in a pregnant patient versus a non-pregnant patient?

Accepted Answer

Faster induction of anesthesia

Answer

Minimal change in depth of anesthesia

Answer

Slower emergence from anesthesia

Answer

No difference

Obstetric Anesthesia — MCQs

Obstetric Anesthesia — MCQs

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