Physiological Changes in Pregnancy — MCQs
Which drug is associated with decreased fetal heart rate during labor?
Anesthesia of choice for cesarean section in severe preeclampsia:-
A lady with 10-12 wks pregnancy develops acute retention of urine. The likely cause is-
All are cardiovascular system changes in pregnancy except.
Functional residual capacity (FRC) is defined as the volume of air remaining in the lungs at which specific moment in the respiratory cycle?
Which of the following parameters is most critical for maintaining optimal oxygenation?
All of the following are physiological changes that occur during pregnancy, except which of the following?
A patient with juvenile myoclonic epilepsy on valproate comes to you at 5 months of pregnancy with a normal level II scan. What will you advise?
Balloon valvotomy is successful in all of the following cases except-
All the following cause malignant hyperpyrexia except?
Physiological Changes in Pregnancy Indian Medical PG Practice Questions and MCQs
Question 1: Which drug is associated with decreased fetal heart rate during labor?
- A. Oxytocin (Correct Answer)
- B. Sodium bicarbonate
- C. IV fluids
- D. Iron
Explanation: ***Oxytocin*** - **Oxytocin** stimulates uterine contractions, which can reduce blood flow to the placenta and temporarily decrease **fetal oxygenation**, leading to **fetal heart rate decelerations**. - Overstimulation of the uterus by oxytocin can result in **tachysystole** (>5 contractions in 10 minutes), potentially causing **fetal hypoxia** and associated changes in fetal heart rate patterns such as late decelerations or bradycardia. *Sodium bicarbonate* - **Sodium bicarbonate** is used to correct metabolic acidosis, but it does not directly affect **fetal heart rate** or uterine activity in a way that causes decelerations. - Its administration is unlikely to impact fetal heart rate unless the underlying condition causing acidosis also affects fetal well-being, which is not a direct drug effect. *IV fluids* - **Intravenous fluids** are often administered during labor to maintain hydration and support maternal circulation, which generally helps improve **fetal well-being** and maintain normal fetal heart rate patterns. - They can help optimize **uterine perfusion**, thereby improving oxygen delivery to the fetus and reducing the risk of fetal distress. *Iron* - **Iron** is essential for red blood cell production and preventing maternal anemia; it has no direct or acute effect on **fetal heart rate** during labor. - Administered as a supplement, iron is not a medication used during labor to impact **uterine contractility** or fetal heart rate in the way oxytocin does.
Question 2: Anesthesia of choice for cesarean section in severe preeclampsia:-
- A. Spinal (Correct Answer)
- B. GA
- C. Epidural
- D. Combined spinal-epidural (CSE)
Explanation: ***Spinal*** - **Spinal anesthesia** is generally preferred in severe preeclampsia because it provides **rapid onset** of dense block, which can be critical for emergent cesarean sections. - It avoids the risks associated with general anesthesia in these patients, such as difficult intubation and exaggerated **hypertensive response** to laryngoscopy. *GA* - **General anesthesia (GA)** in severe preeclampsia carries increased risks due to **airway edema**, potential for difficult intubation, and significant **blood pressure fluctuations** during induction and intubation. - It can exacerbate the already compromised uteroplacental perfusion due to the sympathetic blockade and the potential for a **hypotensive episode**. *Epidural* - While generally safe in less severe preeclampsia, an **epidural** has a **slower onset** compared to spinal anesthesia, which may be a disadvantage in emergent situations. - The gradual sympathetic blockade with an epidural is often preferred to avoid sudden drops in blood pressure, but the delay in achieving a surgical block might not be acceptable in severe, unstable cases. *Combined spinal-epidural (CSE)* - **Combined spinal-epidural (CSE)** offers the rapid onset of a spinal block with the flexibility of an epidural catheter for prolonged anesthesia or postoperative pain control. - However, in cases of severe preeclampsia where **hemodynamic instability** is a major concern, the relatively larger dose of local anesthetic required for epidural component can lead to a more pronounced or rapid drop in blood pressure.
Question 3: A lady with 10-12 wks pregnancy develops acute retention of urine. The likely cause is-
- A. Prolapse uterus
- B. Fibroid
- C. Retroverted uterus (Correct Answer)
- D. Urinary tract infection
Explanation: ***Retroverted uterus*** - A **retroverted uterus** can become impacted in the **pelvic cavity** as it grows during pregnancy, causing compression of the urethra. - This impaction typically occurs between **10-14 weeks of gestation**, leading to acute urinary retention. *Prolapse uterus* - Uterine prolapse is less likely to cause acute urinary retention in early pregnancy, as the pregnant uterus tends to **ascend out of the pelvis** at this stage. - While prolapse can be associated with urinary symptoms, acute retention due to prolapse is more common in **non-pregnant** or **postpartum** states. *Fibroid* - A **fibroid**, especially a large one or one located in the lower uterine segment, can obstruct the bladder outlet. - However, the most classic cause of acute urinary retention in early pregnancy is a **retroverted uterus**, which is more commonly implicated than fibroids in this specific scenario. *Urinary tract infection* - A **urinary tract infection (UTI)** can cause dysuria, frequency, and urgency, and in severe cases, might lead to urinary retention due to urethral inflammation or bladder dysfunction. - While a UTI is possible, in the context of early pregnancy and acute retention, a **mechanical obstruction** from uterine displacement is a more specific and common cause.
Question 4: All are cardiovascular system changes in pregnancy except.
- A. Increase in blood volume
- B. Increase in heart rate
- C. Increase in peripheral resistance (Correct Answer)
- D. Increase in cardiac output
Explanation: ***Increase in peripheral resistance*** - During normal pregnancy, **peripheral vascular resistance actually decreases** due to the effects of hormones like progesterone and the presence of the low-resistance uteroplacental circulation. - This decrease in resistance helps accommodate the increased blood volume and cardiac output. *Increase in cardiac output* - **Cardiac output increases significantly** during pregnancy (by 30-50%) to meet the metabolic demands of the growing fetus and maternal tissues. - This is primarily achieved through an increase in both stroke volume and heart rate. *Increase in blood volume* - **Blood volume increases substantially** (by 30-50%) during pregnancy, with plasma volume increasing more than red blood cell mass. - This expansion supports the increased cardiac output and placental perfusion. *Increase in heart rate* - **Heart rate increases** during pregnancy, typically by 10-20 beats per minute, contributing to the overall increase in cardiac output. - This physiological adaptation helps maintain adequate circulation.
Question 5: Functional residual capacity (FRC) is defined as the volume of air remaining in the lungs at which specific moment in the respiratory cycle?
- A. During active expiration
- B. After normal expiration (Correct Answer)
- C. At peak inspiration
- D. During active inspiration
Explanation: ***After normal expiration*** - **Functional residual capacity (FRC)** is the volume of air remaining in the lungs at the end of a **normal, passive expiration**. - It represents the sum of the **expiratory reserve volume (ERV)** and the **residual volume (RV)**. *During active expiration* - **Active expiration** involves the use of accessory muscles to force more air out of the lungs than during normal expiration. - This process would result in a lung volume less than FRC, closer to the **residual volume**. *At peak inspiration* - **Peak inspiration** represents the total lung capacity (TLC), which is the maximum volume of air the lungs can hold after a maximal inspiratory effort. - This is the largest lung volume, significantly greater than FRC. *During active inspiration* - **Active inspiration** is the process of inhaling air, which increases lung volume. - FRC is a static volume measured at the end of expiration, not during the dynamic process of inhaling.
Question 6: Which of the following parameters is most critical for maintaining optimal oxygenation?
- A. FiO2
- B. Respiratory rate
- C. PEEP (Correct Answer)
- D. Tidal volume
Explanation: ***PEEP*** - **Positive End-Expiratory Pressure (PEEP)** is crucial for maintaining optimal oxygenation because it prevents **alveolar collapse** at the end of expiration, thereby increasing the **functional residual capacity** and improving gas exchange. - By keeping alveoli open, PEEP increases the number of available alveoli for ventilation, preventing **atelectasis** and optimizing the **venous admixture** from non-ventilated lung units. *FiO2* - While **Fraction of Inspired Oxygen (FiO2)** is essential for providing sufficient oxygen, simply increasing FiO2 without proper alveolar recruitment and patency (often achieved with PEEP) can be less effective and potentially harmful due to **oxygen toxicity**. - High FiO2 can improve oxygenation in cases of **hypoxemia**, but it doesn't address underlying problems like **alveolar collapse** or **ventilation-perfusion mismatch** as directly as PEEP does. *Respiratory rate* - **Respiratory rate** primarily affects **carbon dioxide elimination** (PaCO2) and, to some extent, alveolar ventilation. - While an adequate respiratory rate is necessary for overall gas exchange, it is not the most direct or critical parameter for optimizing **oxygenation** compared to PEEP's role in maintaining alveolar patency. *Tidal volume* - **Tidal volume** also primarily affects **carbon dioxide elimination** and plays a role in overall minute ventilation. - Excessive tidal volume can lead to **ventilator-induced lung injury (VILI)**, while insufficient tidal volume can reduce minute ventilation, but it does not directly optimize oxygenation by preventing **alveolar collapse** in the same way PEEP does.
Question 7: All of the following are physiological changes that occur during pregnancy, except which of the following?
- A. Decrease in renal plasma flow (Correct Answer)
- B. Increase in cardiac output
- C. Increase in glomerular filtration rate
- D. Increase in blood volume
Explanation: ***Decrease in renal plasma flow*** - This statement is incorrect because **renal plasma flow actually increases** significantly during pregnancy due to vasodilation. - The increased renal plasma flow contributes to the elevated **glomerular filtration rate** observed in pregnant women. *Increase in cardiac output* - **Cardiac output increases by 30-50%** during pregnancy to meet the metabolic demands of the growing fetus and maternal tissues. - This increase is primarily due to an increase in both **heart rate** and **stroke volume**. *Increase in glomerular filtration rate* - The **glomerular filtration rate (GFR) increases by 30-50%** during pregnancy, leading to increased renal clearance of waste products. - This physiologic change is partly due to the **increased renal plasma flow** and changes in renal hemodynamics. *Increase in blood volume* - **Blood volume increases by 30-50%** during pregnancy, with a proportionally greater increase in plasma volume compared to red blood cell mass. - This expansion in blood volume is crucial for meeting the demands of the uteroplacental circulation and protecting against hemorrhage during delivery.
Question 8: A patient with juvenile myoclonic epilepsy on valproate comes to you at 5 months of pregnancy with a normal level II scan. What will you advise?
- A. Increase the dose of the drug
- B. Change the drug
- C. Decrease the dose of the drug
- D. Continue the drug in the same dose (Correct Answer)
Explanation: ***Continue the drug in the same dose*** - As the patient is already at **5 months of pregnancy** with a **normal level II scan**, the risk of major congenital malformations has largely passed. - **Maintaining seizure control** is crucial during pregnancy, as uncontrolled seizures pose significant risks to both the mother and fetus. *Change the drug* - Changing an antiepileptic drug during pregnancy, especially in the second trimester, can lead to a **loss of seizure control** and potentially expose the fetus to a new drug with unknown risks. - The period of highest risk for **major congenital malformations** from valproate exposure is during the first trimester. *Decrease the dose of the drug* - Decreasing the dose of valproate could lead to **breakthrough seizures**, which are dangerous for both the mother and the fetus. - **Plasma drug levels** often decrease in pregnancy due to increased volume of distribution and metabolism, potentially requiring a stable or even increased dose to maintain therapeutic levels. *Increase the dose of the drug* - Increasing the dose without clear clinical indication (e.g., breakthrough seizures or subtherapeutic levels) could increase the risk of **dose-dependent side effects** for both mother and fetus. - While therapeutic drug monitoring for valproate is often done in pregnancy, a **normal level II scan** does not automatically warrant a dose increase.
Question 9: Balloon valvotomy is successful in all of the following cases except-
- A. Calcified mitral stenosis (Correct Answer)
- B. Congenital aortic stenosis
- C. Congenital pulmonary stenosis
- D. Mitral stenosis in pregnancy
Explanation: ***Calcified mitral stenosis*** - **Balloon valvotomy is LEAST successful** in **calcified mitral stenosis** due to the reduced ability of the calcified valve leaflets to split properly, increasing the risk of suboptimal results and complications like **mitral regurgitation**. - The presence of **significant calcification** (Wilkins score >8) is a relative **contraindication** and often necessitates **surgical valve replacement** rather than percutaneous repair. - Heavy calcification predicts poor outcomes with high rates of procedural failure and need for early surgery. *Congenital aortic stenosis* - Balloon valvotomy can be performed for **congenital aortic stenosis**, particularly in children and young adults as a **palliative or temporizing measure**. - However, it has **significant limitations** including high rates of **restenosis** (up to 25-40%) and **aortic regurgitation**, often requiring repeat intervention or surgical valve replacement. - It is less successful than balloon valvotomy for pulmonary stenosis but may provide symptomatic relief and delay the need for surgery in selected cases. *Congenital pulmonary stenosis* - **Congenital pulmonary stenosis** is the **MOST FAVORABLE** condition for **balloon valvotomy**, with high success rates (>90%) and excellent long-term outcomes, especially for isolated valvar stenosis. - It is the **treatment of choice** (gold standard) for significant valvar pulmonary stenosis and effectively relieves right ventricular outflow obstruction. *Mitral stenosis in pregnancy* - **Balloon mitral valvotomy** is a safe and effective treatment option for **severe mitral stenosis** during **pregnancy** when valve morphology is favorable (pliable, non-calcified valves). - It can alleviate symptoms and improve maternal and fetal outcomes without exposing the fetus to the risks of cardiopulmonary bypass required for open-heart surgery. - The procedural risk is generally low, and it helps manage the increased hemodynamic burden of pregnancy.
Question 10: All the following cause malignant hyperpyrexia except?
- A. Methoxyflurane
- B. N20 (Correct Answer)
- C. Isoflurane
- D. Halothane
Explanation: ***N2O*** - **Nitrous oxide (N2O)**, or laughing gas, is an inhaled anesthetic that does not trigger **malignant hyperthermia (MH)**. - It is often used as a carrier gas or adjunct during anesthesia, even in patients susceptible to MH, as it does not affect **ryanodine receptors**. *Methoxyflurane* - **Methoxyflurane** is a volatile inhaled anesthetic known to trigger **malignant hyperthermia (MH)** in susceptible individuals. - It causes an uncontrolled release of **calcium** from the sarcoplasmic reticulum in muscle cells, leading to severe hypermetabolism. *Isoflurane* - **Isoflurane** is a commonly used volatile inhaled anesthetic that can induce **malignant hyperthermia (MH)** in genetically predisposed individuals. - Like other volatile agents, it activates **ryanodine receptors** in skeletal muscle, leading to excessive muscle contraction and heat production. *Halothane* - **Halothane** is a potent volatile inhaled anesthetic historically associated with a high incidence of triggering **malignant hyperthermia (MH)**. - Its use has largely been replaced by newer agents due to concerns about MH and **hepatotoxicity**.
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