Obstetric Anesthesia Practice Questions

Q: Which of the following modalities of anesthesia cannot be used for LSCS?

Saddle anesthesia. **Explanation:** The correct answer is **Saddle Anesthesia**. **1. Why Saddle Anesthesia is incorrect for LSCS:** Saddle anesthesia is a form of low spinal anesthesia that targets the lower sacral nerves (S2-S4). It provides sensory loss restricted to the perineum, perianal area, and inner thighs—the areas that would touch a saddle. While it is suitable for vaginal deliveries, outlet forceps, or perineal surgeries, it is **inadequate for Lower Segment Cesarean Section (LSCS)**. An LSCS requires a sensory block level of at least **T4 (nipple line)** to ensure the patient does not feel the abdominal incision or the exteriorization of the uterus. **2. Analysis of other options:** * **General Anesthesia (GA):** Used in emergencies (e.g., fetal distress, cord prolapse) or when regional anesthesia is contraindicated. It provides rapid onset but carries risks of aspiration and difficult airway. * **Spinal Anesthesia (SAB):** The "Gold Standard" for elective LSCS. It provides a dense, rapid block. A level of T4 is targeted. * **Epidural Anesthesia:** Commonly used when a labor epidural is already in place and "topped up" for surgery, or for cases where a slower onset of sympathetic blockade is desired. **3. Clinical Pearls for NEET-PG:** * **Target Level for LSCS:** T4 (to prevent pain from peritoneal traction). * **Target Level for Vaginal Delivery:** T10 (to cover uterine contractions). * **Most common complication of Spinal Anesthesia in pregnancy:** Hypotension (due to aortocaval compression and sympathetic block). * **Drug of choice for hypotension in pregnancy:** Phenylephrine (preferred over Ephedrine as it maintains better fetal pH).

Q: A 28-year-old G3P2 parturient is undergoing general anesthesia for emergency cesarean section due to uterine rupture. All of the following findings would suggest an amniotic fluid embolism, except:

Increased maternal pH. **Explanation:** Amniotic Fluid Embolism (AFE) is a catastrophic obstetric emergency characterized by a triad of **hypoxia, hypotension, and coagulopathy**. **1. Why "Increased maternal pH" is the correct (except) answer:** AFE leads to sudden cardiovascular collapse and profound respiratory failure. This results in severe **metabolic acidosis** (due to low cardiac output and tissue hypoxia) and **respiratory acidosis** (due to ventilation-perfusion mismatch). Therefore, the maternal pH will be **decreased**, not increased. **2. Analysis of incorrect options:** * **Decreased EtCO2:** AFE causes a sudden mechanical obstruction of the pulmonary vasculature and intense pulmonary vasospasm. This leads to a massive increase in alveolar dead space, causing a sharp drop in End-tidal CO2 (EtCO2). * **Bleeding diathesis:** Up to 80% of AFE patients develop Disseminated Intravascular Coagulation (DIC). Amniotic fluid contains tissue factor which triggers the extrinsic clotting cascade, leading to consumption coagulopathy and massive hemorrhage. * **Upsloping EtCO2 tracing:** In the acute phase of AFE, severe bronchospasm often occurs (anaphylactoid reaction). On a capnograph, bronchospasm manifests as a "shark-fin" appearance or an **upsloping Phase III**, indicating obstructive physiology. **Clinical Pearls for NEET-PG:** * **Classic Triad:** Hypoxia, Hypotension, and Coagulopathy (DIC). * **Pathophysiology:** Now considered an "Anaphylactoid Syndrome of Pregnancy" rather than a simple embolic event. * **Diagnosis:** Primarily a diagnosis of exclusion; presence of fetal squames in pulmonary circulation is suggestive but not pathognomonic. * **Management:** Supportive (A-B-C). The **A-OK protocol** (Atropine, Ondansetron, Ketorolac) is a modern pharmacological approach used to counter the vasospasm and inflammatory surge.

Q: Which anesthetic agent can have a teratogenic effect?

Nitrous oxide (N2O). **Explanation:** The correct answer is **Nitrous oxide (N2O)**. **Why Nitrous Oxide is the Correct Answer:** Nitrous oxide is the only anesthetic agent listed with a proven mechanism for potential teratogenicity. It inhibits the enzyme **Methionine Synthase**, which is responsible for converting homocysteine to methionine. This inhibition disrupts the **Vitamin B12 metabolism**, leading to a decrease in DNA synthesis and cell division. In animal studies, prolonged exposure to high concentrations of N2O has been linked to skeletal abnormalities and fetal resorptions. While clinical evidence in humans is limited, it is traditionally avoided or used with caution during the **first trimester** (organogenesis) of pregnancy. **Why the Other Options are Incorrect:** * **Halothane, Isoflurane, and Desflurane (Volatile Anesthetics):** These halogenated agents are not considered teratogenic in humans. While they can cause dose-dependent uterine relaxation and maternal hypotension (which may affect placental perfusion), they do not interfere with DNA synthesis or metabolic pathways essential for organogenesis. **High-Yield Clinical Pearls for NEET-PG:** * **Safe Period:** Surgery during pregnancy is ideally performed during the **second trimester** to minimize the risk of teratogenesis (1st trimester) and preterm labor (3rd trimester). * **MAC in Pregnancy:** The Minimum Alveolar Concentration (MAC) of volatile anesthetics is **decreased by 30-40%** due to increased progesterone levels and endogenous opioid activity. * **Aspiration Risk:** Pregnant patients are always considered "full stomach" after the first trimester due to increased intra-abdominal pressure and decreased lower esophageal sphincter tone. * **Fetal Oxygenation:** The most important factor in preventing fetal demise during non-obstetric surgery is maintaining **maternal normotension and oxygenation**.

Q: A paracervical block relieves pain from all but one of the following. Which is it?

Pain from the lower third of the vagina and episiotomy. ### Explanation The **Paracervical Block (PCB)** is a regional anesthetic technique used primarily during the **first stage of labor**. To understand why it fails to provide anesthesia for an episiotomy, one must understand the dual innervation of the female reproductive tract. **1. Why Option C is Correct:** The paracervical block targets the **Frankenhauser’s plexus** (uterovaginal plexus), which carries visceral sensory fibers from the uterus, cervix, and the upper portion of the vagina. These fibers travel alongside sympathetic nerves to enter the spinal cord at **T10–L1**. However, the **lower third of the vagina, the perineum, and the site for an episiotomy** are innervated by the **Pudendal Nerve (S2–S4)**. Since the paracervical block does not affect the sacral nerves, it provides no relief for the second stage of labor or perineal procedures. **2. Analysis of Incorrect Options:** * **Options A & B:** Dilatation of the cervix and uterine contractions are the primary sources of pain in the first stage of labor. These impulses travel via the paracervical plexus; thus, PCB is highly effective for these. * **Option D:** The upper third of the vagina derives its nerve supply from the uterovaginal plexus, which is successfully anesthetized by a paracervical block. **3. High-Yield Clinical Pearls for NEET-PG:** * **Indication:** Specifically for the **first stage of labor** (cervical dilatation). * **Major Complication:** **Fetal Bradycardia** (occurs in up to 15% of cases). This is thought to be due to uterine artery vasoconstriction or direct fetal toxicity from local anesthetic absorption. * **Contraindication:** It should not be used if there is evidence of **fetal distress** or placental insufficiency. * **Anatomy:** The injection is made into the lateral vaginal fornices at the 3 and 9 o'clock positions.

Q: Internal podalic version is typically performed under which type of anesthesia?

General anesthesia. **Explanation:** **Internal Podalic Version (IPV)** is an obstetric maneuver used to convert a non-vertex presentation (usually a transverse lie of a second twin) into a breech presentation by reaching into the uterus, grasping the feet, and pulling them through the cervix. **Why General Anesthesia (GA) is correct:** The primary requirement for a successful IPV is **profound uterine relaxation**. A contracted uterus tightly encircling the fetus makes manipulation impossible and significantly increases the risk of uterine rupture. GA using **volatile inhalational agents** (like Halothane, Isoflurane, or Sevoflurane) at high concentrations provides rapid and reliable uterine relaxation (tocolysis), allowing the obstetrician to reach the feet and turn the fetus safely. **Why other options are incorrect:** * **Pudendal Block:** This only provides anesthesia to the perineum and vagina. It offers no pain relief for intrauterine manipulation and zero uterine relaxation. * **Intravenous Diazepam:** While it provides sedation and minimal skeletal muscle relaxation, it does not relax the smooth muscles of the uterus. * **Spinal Anesthesia:** While excellent for pain relief, neuraxial blocks (Spinal/Epidural) do not provide uterine relaxation. In fact, they may increase uterine tone due to sympathetic blockade, making version more difficult. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice for Rapid Relaxation:** If GA is not used, **IV Nitroglycerin (NTG)** is the pharmacological agent of choice for rapid, short-acting uterine relaxation during obstetric emergencies. * **Twin Delivery:** IPV is most commonly indicated for the **delivery of the second twin** in a transverse lie. * **Uterine Relaxants in Anesthesia:** Halogenated inhalational agents are potent uterine relaxants; this is beneficial for IPV but a disadvantage during the third stage of labor as it can lead to **Postpartum Hemorrhage (PPH)** due to uterine atony.

Question 1

Which of the following modalities of anesthesia cannot be used for LSCS?

Accepted Answer

Saddle anesthesia

Answer

General anesthesia

Answer

Spinal anesthesia

Answer

Epidural anesthesia

Question 2

What is the preferred anaesthesia for Cesarean delivery in patients with stable placenta previa?

Accepted Answer

Epidural Anaesthesia

Answer

Spinal Anaesthesia

Answer

General Anaesthesia

Answer

Combined spinal and epidural anaesthesia

Question 3

A 28-year-old G3P2 parturient is undergoing general anesthesia for emergency cesarean section due to uterine rupture. All of the following findings would suggest an amniotic fluid embolism, except:

Accepted Answer

Increased maternal pH

Answer

Decreased EtCO2

Answer

Bleeding diathesis

Answer

Upsloping EtCO2 tracing

Question 4

Which anesthetic agent can have a teratogenic effect?

Accepted Answer

Nitrous oxide (N2O)

Answer

Halothane

Answer

Isoflurane

Answer

Desflurane

Question 5

Epidural anesthesia is initiated in a primigravida at 38 weeks gestation with a bolus of 15mg of bupivacaine. Within a few minutes, fetal heart rate monitoring shows variable decelerations. If scalp pH reveals fetal acidosis, compared with a normal pH, what is the state of the anesthetic absorbed by the fetus?

Accepted Answer

Higher concentration, mostly in ionized form

Answer

Lower concentration, mostly in ionized form

Answer

Higher concentration, mostly in unionized form

Answer

Unchanged concentration, equal fraction of ionized and unionized

Question 6

A paracervical block relieves pain from all but one of the following. Which is it?

Accepted Answer

Pain from the lower third of the vagina and episiotomy

Answer

Pain from dilatation of the cervix

Answer

Uterine pain

Answer

Pain from the upper third of the vagina

Question 7

For operative vaginal delivery, what is the level of sensory block needed to cover pain?

Accepted Answer

S2-S4

Answer

T10-L1

Answer

T10-S1

Answer

L1-S1

Question 8

What is the best method of analgesia for a 25-year-old primigravida with mitral stenosis and mitral regurgitation who desires a normal delivery?

Accepted Answer

Neuraxial blockade analgesia

Answer

Inhalational analgesia

Answer

Intravenous opioids

Answer

Spinal anesthesia

Question 9

Internal podalic version is typically performed under which type of anesthesia?

Accepted Answer

General anesthesia

Answer

Pudendal block

Answer

Intravenous diazepam

Answer

Spinal anesthesia

Question 10

A patient at 38 weeks of gestation with pre-eclampsia is started on oxytocin to augment her labor and requests epidural analgesia. What are the key anesthetic considerations?

Accepted Answer

The presence of hypertension and edema requires further workup before proceeding with epidural anesthesia.

Answer

No workup is required prior to performing epidural anesthesia, as this will treat her hypertension.

Answer

Neuraxial anesthesia should be avoided due to an increased risk of bleeding.

Answer

Systemic opiates should be avoided as the risk of respiratory depression is too high.

Obstetric Anesthesia — MCQs

Obstetric Anesthesia — MCQs

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