Labor and Delivery Practice Questions

Q: Which pelvic plane is most important in obstructed labor?

Plane of least pelvic dimension. ### Explanation The **Plane of Least Pelvic Dimension** (also known as the **Mid-pelvis**) is the most critical plane in obstructed labor because it is the narrowest part of the pelvic canal through which the fetal head must pass. **1. Why the Correct Answer is Right:** The plane of least pelvic dimension is bounded anteriorly by the lower border of the symphysis pubis, laterally by the **ischial spines**, and posteriorly by the tip of the sacrum. Because the interspinous diameter (approx. 10.5 cm) is the shortest diameter of the entire pelvis, this plane represents the most common site of **arrest of descent**. Internal rotation of the fetal head typically occurs at this level; failure to rotate or descend through this "bottleneck" results in obstructed labor. **2. Why the Other Options are Incorrect:** * **Plane of Inlet (A):** While "cephalopelvic disproportion" can occur here, the inlet is generally wider (transverse diameter ~13 cm). If the head engages, the inlet is bypassed. * **Plane of Outlet (B):** The outlet is diamond-shaped and consists of two muscle-bound triangles. It is rarely the primary site of obstruction unless there is a severe coccygeal deformity or an extremely narrow pubic arch. * **Plane of Greatest Pelvic Dimension (C):** As the name suggests, this is the roomiest part of the pelvis (extending from the mid-symphysis to the junction of S2-S3). Obstruction never occurs here. **3. NEET-PG High-Yield Pearls:** * **Obstetric Conjugate:** The most important diameter of the pelvic **inlet** (measured as Diagonal Conjugate minus 1.5–2 cm). * **Station Zero:** The fetal bony vertex is at the level of the **ischial spines** (Plane of least dimension). * **Mid-pelvic Contraction:** Suspected if the interspinous diameter is <10 cm. * **Clinical Landmark:** The ischial spines are the landmarks for administering a **pudendal nerve block**.

Q: Which of the following drugs is contraindicated for controlling atonic hemorrhage in a preeclamptic woman?

Methylergonovine. **Explanation:** The management of Postpartum Hemorrhage (PPH) in a patient with preeclampsia requires careful selection of uterotonics to avoid exacerbating underlying hypertension. **Why Methylergonovine is the Correct Answer:** Methylergonovine (Methergine), an ergot alkaloid, acts directly on the smooth muscles of the uterus and blood vessels. Its primary side effect is **generalized vasoconstriction**, which can lead to a sudden and severe increase in blood pressure (hypertensive crisis), stroke, or myocardial infarction. In a preeclamptic patient who already has compromised vascular resistance and endothelial dysfunction, Methylergonovine is **strictly contraindicated**. **Analysis of Incorrect Options:** * **Oxytocin (Option A):** This is the first-line drug for PPH in all patients, including those with preeclampsia. It causes rhythmic uterine contractions without significant effects on blood pressure when given as a slow infusion. * **Misoprostol (Option B):** A PGE1 analogue that is safe in hypertensive patients. It is typically administered sublingually or rectally and does not affect blood pressure. * **PGF2 alfa (Carboprost) (Option D):** This is a potent uterotonic used when oxytocin fails. While it is **contraindicated in asthmatics** (due to bronchoconstriction), it is safe to use in preeclamptic patients as it does not significantly elevate systemic blood pressure. **High-Yield Clinical Pearls for NEET-PG:** * **Methergine Contraindication:** Hypertension/Preeclampsia/Eclampsia. * **Carboprost (PGF2α) Contraindication:** Asthma. * **Misoprostol (PGE1) Contraindication:** Known hypersensitivity (generally safe in most systemic diseases). * **Active Management of Third Stage of Labor (AMTSL):** Oxytocin (10 IU IM) is the drug of choice. * **Ergotism:** Chronic toxicity of ergot alkaloids leading to gangrene (due to vasoconstriction) or convulsions.

Q: All of the following are methods of induction of labour except?

Estrogen. **Explanation:** Induction of labor (IOL) refers to the artificial stimulation of uterine contractions before the spontaneous onset of labor for the purpose of accomplishing delivery. **Why Estrogen is the Correct Answer:** While estrogen levels naturally rise during pregnancy and help increase the number of oxytocin receptors and gap junctions in the myometrium (preparing the uterus for labor), **exogenous estrogen is not a clinical method used for the induction of labor.** It lacks the immediate efficacy required to initiate active contractions and has no established role in modern obstetric protocols for IOL. **Analysis of Incorrect Options:** * **Oxytocin:** The most common pharmacological agent used for IOL. It acts directly on the oxytocin receptors in the myometrium to initiate and strengthen uterine contractions. * **Stripping of Membranes:** A mechanical method of induction. The clinician rotates a finger between the lower uterine segment and the fetal membranes, which triggers the local release of endogenous prostaglandins (PGF2α). * **PGE2 (Dinoprostone):** A prostaglandin used primarily for cervical ripening (Bishop score <6). It acts by breaking down collagen in the cervix and stimulating uterine smooth muscle. **High-Yield Clinical Pearls for NEET-PG:** * **Bishop Score:** The most important predictor of successful induction. A score of **≥8** suggests a high likelihood of successful vaginal delivery. * **Drug of Choice:** PGE2 (Dinoprostone) is preferred for an unfavorable cervix, while Oxytocin is preferred if the cervix is favorable or membranes are ruptured. * **PGE1 (Misoprostol):** Also used for induction but is contraindicated in patients with a previous cesarean section due to the high risk of uterine rupture. * **Mechanical Methods:** Include Foley’s catheter bulb induction and Artificial Rupture of Membranes (ARM/Amniotomy).

Q: What is the normal bispinous diameter of the pelvis?

10.5 cm. **Explanation:** The **bispinous diameter** (also known as the interspinous diameter) is the transverse diameter of the **pelvic outlet** (specifically the plane of least pelvic dimensions). It represents the distance between the two ischial spines. 1. **Why 10.5 cm is correct:** In a standard gynecoid pelvis, the bispinous diameter measures approximately **10.5 cm**. This is clinically the narrowest part of the pelvic canal through which the fetal head must pass. It serves as the landmark for "zero station" and is the level where internal rotation of the fetal head typically occurs. 2. **Why other options are incorrect:** * **11.5 cm:** This is closer to the **obstetric conjugate** (anteroposterior diameter of the inlet) or the **transverse diameter of the outlet** (between ischial tuberosities, which is ~11 cm). * **12.5 cm:** This corresponds to the **oblique diameter** of the pelvic inlet or the **transverse diameter of the mid-cavity**. * **9.5 cm:** This is too narrow for a normal pelvis; a bispinous diameter of less than 9.0–9.5 cm usually indicates mid-pelvic contraction, which can lead to deep transverse arrest. **High-Yield Clinical Pearls for NEET-PG:** * **Narrowest Diameter:** The bispinous diameter is the shortest diameter of the pelvis. * **Mid-pelvic Contraction:** If the sum of the bispinous and posterior sagittal diameters is less than 13.5 cm, mid-pelvic contraction is suspected. * **Ischial Spines:** These are the most important landmarks during a vaginal examination to assess the descent of the fetal head (Station 0). * **Shape Association:** A narrow bispinous diameter is frequently seen in **Android** and **Anthropoid** pelvises.

Q: What is the treatment of choice in a primigravida at term in labor with a transverse lie and cervical dilatation of 6 cm with intact membranes?

Lower segment cesarean section. **Explanation:** In a **primigravida** at term with a **transverse lie**, the fetus cannot be delivered vaginally. Once labor has commenced (indicated here by 6 cm cervical dilatation), the risk of complications such as cord prolapse or obstructed labor with impending uterine rupture increases significantly. **1. Why Lower Segment Cesarean Section (LSCS) is the Correct Choice:** For a transverse lie at term in labor, **LSCS is the treatment of choice**. In a primigravida, the uterus is non-compliant, and the risk of uterine rupture during any intrauterine manipulation is high. Since the patient is already in active labor (6 cm), external cephalic version is contraindicated. LSCS ensures the safety of both the mother and the fetus by avoiding the trauma of obstructed labor. **2. Why Other Options are Incorrect:** * **Wait and watch:** A transverse lie is an absolute mechanical obstruction. Waiting will lead to "neglected shoulder presentation," cord prolapse, or uterine rupture. * **Internal Podalic Version (IPV):** IPV is strictly contraindicated in a singleton pregnancy at term with a live fetus. It is currently only indicated for the delivery of the **second twin** (non-vertex). * **Bipolar Version:** This is an obsolete procedure (MacDonald’s version) used in the past for placenta previa or to bring down a foot; it has no role in modern obstetric management of transverse lie. **Clinical Pearls for NEET-PG:** * **Most common cause** of transverse lie in primigravida: Pelvic contraction or placenta previa. * **Management of Transverse Lie:** * *Not in labor:* External Cephalic Version (ECV) can be attempted after 37 weeks. * *In labor:* Always LSCS (regardless of whether membranes are intact or ruptured). * **The "Hand-Prolapse":** If you see a hand prolapsing through the vagina in labor, the diagnosis is transverse lie; the immediate step is LSCS.

Q: What is the most common cause of breech presentation?

Prematurity. **Explanation:** **1. Why Prematurity is the Correct Answer:** The most significant factor determining fetal presentation is the relationship between fetal size and amniotic fluid volume. In early pregnancy, the fetus is small relative to the volume of liquor, allowing for free movement. As the pregnancy advances towards term, the fetus grows and the "Law of Accommodation" takes effect: the fetus maneuvers to fit its bulkier part (the buttocks and lower limbs) into the wider fundus of the uterus, while the smaller head engages in the narrower lower segment. Since the majority of fetuses spontaneously version to cephalic by 34 weeks, any delivery occurring before this time (prematurity) is statistically the most common cause of breech presentation. At 28 weeks, approximately 25% of fetuses are breech, whereas only 3-4% remain breech at term. **2. Analysis of Incorrect Options:** * **Contracted Pelvis:** While a narrow pelvis can prevent the head from engaging (leading to malpresentation), it is a much rarer clinical finding compared to the frequency of preterm births. * **Oligohydramnios:** Reduced amniotic fluid actually restricts fetal movement. While it can "trap" a fetus in a breech position if it is already there, it is not the *most common* cause. * **Placenta Previa:** A low-lying placenta can occupy the lower uterine segment, preventing the head from entering the pelvis. While a recognized risk factor, it occurs in less than 1% of pregnancies. **3. NEET-PG High-Yield Pearls:** * **Most common type of breech:** Frank breech (especially in primigravidae at term). * **Most common cause of breech at term:** Idiopathic. * **Best time for External Cephalic Version (ECV):** 36 weeks in primigravida; 37 weeks in multigravida. * **Prerequisite for vaginal breech delivery:** Spontaneous onset of labor, frank breech, and an estimated fetal weight between 2.5kg and 3.5kg.

Q: Labour is said to be prolonged when the first and second stage extend arbitrarily beyond which duration?

18 hours. **Explanation:** In clinical obstetrics, **Prolonged Labor** is defined as labor lasting for more than **18 hours**. This duration is calculated as the combined time of the first and second stages of labor. 1. **Why 18 hours is correct:** Traditionally, the upper limit of normal labor is considered 18 hours. Beyond this threshold, there is a significant increase in maternal and neonatal morbidity, including maternal exhaustion, dehydration, and an increased risk of chorioamnionitis and fetal distress. 2. **Why other options are incorrect:** * **12 hours (Option A):** While many primigravida labors conclude within 12 hours, it is still within the physiological range and not yet classified as "prolonged." * **24 hours (Option C):** Historically, 24 hours was used as the cutoff (often termed "Protracted Labor"), but modern obstetric guidelines (WHO) have shifted the threshold to 18 hours to allow for earlier intervention and better outcomes. * **6 hours (Option D):** This is far too short; the latent phase alone in a primigravida can normally last up to 20 hours. **High-Yield Clinical Pearls for NEET-PG:** * **Friedman’s Curve:** Traditionally used to track cervical dilation over time. * **WHO Partograph:** The "Alert line" and "Action line" are separated by **4 hours**. If the labor curve crosses the Action line, intervention is required. * **Stage-specific Prolongation:** * **Second Stage:** Prolonged if it exceeds 2 hours in primigravida (3 hours with epidural) or 1 hour in multigravida (2 hours with epidural). * **Commonest Cause:** The most frequent cause of prolonged labor is **Cephalopelvic Disproportion (CPD)** or malpresentation (e.g., Occipito-posterior position).

Question 1

Which pelvic plane is most important in obstructed labor?

Accepted Answer

Plane of least pelvic dimension

Answer

Plane of inlet

Answer

Plane of outlet

Answer

Plane of greatest pelvic dimension

Question 2

Inversion of the uterus is not caused by which of the following?

Accepted Answer

Controlled cord traction

Answer

Undue fundal pressure

Answer

Fundal attachment of placenta

Answer

Faulty placental extraction

Question 3

Which of the following drugs is contraindicated for controlling atonic hemorrhage in a preeclamptic woman?

Accepted Answer

Methylergonovine

Answer

Oxytocin

Answer

Misoprostol

Answer

PGF2 alfa

Question 4

All of the following are methods of induction of labour except?

Accepted Answer

Estrogen

Answer

Oxytocin

Answer

Stripping of membrane

Answer

PGE2

Question 5

What is the normal bispinous diameter of the pelvis?

Accepted Answer

10.5 cm

Answer

11.5 cm

Answer

12.5 cm

Answer

9.5 cm

Question 6

All of the following are features of obstructed labor, except?

Accepted Answer

Unruptured membranes present

Answer

Hot dry vagina

Answer

Bandl's Ring

Answer

Tonic contracted uterus

Question 7

What is the treatment of choice in a primigravida at term in labor with a transverse lie and cervical dilatation of 6 cm with intact membranes?

Accepted Answer

Lower segment cesarean section

Answer

Wait and watch until full dilation of the cervix

Answer

Internal podalic version and breech extraction

Answer

Bipolar version

Question 8

A 30-year-old woman with a previous history of stillbirth at 24 weeks of gestation is now at 30 weeks of gestation. What is her obstetric score?

Accepted Answer

G2P1L0

Answer

G1Ab1

Answer

G2Ab1

Answer

G2P2L0

Question 9

What is the most common cause of breech presentation?

Accepted Answer

Prematurity

Answer

Contracted pelvis

Answer

Oligohydramnios

Answer

Placenta previa

Question 10

Labour is said to be prolonged when the first and second stage extend arbitrarily beyond which duration?

Accepted Answer

18 hours

Answer

12 hours

Answer

24 hours

Answer

6 hours

Labor and Delivery — MCQs

Labor and Delivery — MCQs

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