Labor and Delivery Practice Questions

Q: What is the most commonly encountered presenting part in a longitudinal lie?

Vertex. **Explanation:** In obstetrics, **lie** refers to the relationship between the long axis of the fetus and the long axis of the mother. In a **longitudinal lie** (99% of term pregnancies), the fetus is oriented vertically. The **presenting part** is the portion of the fetus that lies over the internal os of the cervix. **Vertex** is the correct answer because it is the most common presentation within a longitudinal lie, occurring in approximately **95-96%** of all deliveries. This occurs when the fetal head is well-flexed, bringing the area between the anterior and posterior fontanelles (the vertex) to the cervix. This is the most favorable position for vaginal delivery as it presents the smallest diameter (**suboccipitobregmatic**, 9.5 cm) to the birth canal. **Incorrect Options:** * **Brow (A):** This occurs when the head is partially extended. It is the rarest presentation because it is usually unstable, typically converting to a vertex or face presentation. * **Face (B):** This occurs when the head is completely hyperextended. It is much less common than vertex (approx. 0.2% of births). * **Hand (D):** A hand presenting alongside the head is termed a **compound presentation**. It does not constitute the primary presenting part of a longitudinal lie and is often associated with prematurity or malpresentation. **High-Yield Clinical Pearls for NEET-PG:** * **Cephalic presentation** includes vertex, brow, and face. Vertex is the "norm." * The most common position within a vertex presentation is **Left Occipito-Anterior (LOA)**. * If the lie is **transverse**, the presenting part is typically the **shoulder** (acromion). * The denominator for a vertex presentation is the **Occiput**; for face, it is the **Mentum**; and for breech, it is the **Sacrum**.

Q: What is the common cause of retained placenta?

Atonic uterus. **Explanation:** **Retained placenta** is defined as the failure of the placenta to be expelled within 30 minutes of the birth of the baby (with active management). 1. **Why Atonic Uterus is correct:** The most common cause of a retained placenta is **uterine atony**. For the placenta to separate and be expelled, the myometrium must contract and retract effectively. These contractions reduce the surface area of the placental site, leading to cleavage through the decidua spongiosa. In an atonic uterus, the lack of muscular contraction prevents this separation and subsequent expulsion, making it the leading etiology in clinical practice. 2. **Analysis of Incorrect Options:** * **Constriction ring (Hourglass contraction):** This occurs when a localized ring of uterine spasm (often at the internal os) traps a separated placenta. While a known cause, it is less frequent than simple atony. * **Placenta accreta:** This involves morbid adhesion where chorionic villi invade the myometrium due to a defective decidua basalis. While it causes severe retention, it is a rare pathological condition compared to atony. * **Poor voluntary expulsive effort:** While this may delay the second stage of labor, the expulsion of the placenta (third stage) depends primarily on uterine contractions, not maternal pushing. **High-Yield NEET-PG Pearls:** * **Management:** The first step for a retained placenta is **Manual Removal of Placenta (MROP)** under general anesthesia. * **Risk:** The most significant immediate complication of a retained placenta is **Postpartum Hemorrhage (PPH)**. * **Active Management of Third Stage of Labor (AMTSL):** Reduces the incidence of retained placenta and PPH; the drug of choice is **Oxytocin (10 IU IM)**.

Q: Persistent occipitoposterior presentation is common in which type of pelvis?

Android pelvis. **Explanation:** The orientation of the fetal head during labor is significantly influenced by the shape of the pelvic inlet and the available space in the forepelvis. **1. Why Android Pelvis is Correct:** The **Android (masculine) pelvis** is characterized by a heart-shaped inlet with a narrow, triangular forepelvis and a wide hindpelvis. Because the anterior segment is cramped, the fetal head is forced to occupy the roomier posterior segment. This favors an **Occipitoposterior (OP)** position. Furthermore, the convergent side walls and prominent ischial spines in an android pelvis often lead to a failure of internal rotation, resulting in **Persistent Occipitoposterior** position or deep transverse arrest. **2. Analysis of Incorrect Options:** * **Anthropoid Pelvis:** This pelvis has a long anteroposterior diameter and a narrow transverse diameter. While it is the most common pelvis associated with a fetus *starting* in an OP position (Direct OP), the spacious AP diameter often allows for easier delivery or spontaneous rotation compared to the android type. * **Gynaecoid Pelvis:** The "ideal" female pelvis. It is round/oval with adequate space in all segments, favoring the Occipito-anterior (OA) position and smooth internal rotation. * **Platypelloid Pelvis:** A "flat" pelvis with a short AP and wide transverse diameter. This type typically leads to **Persistent Transverse** positions (asynclitism) rather than OP. **NEET-PG High-Yield Pearls:** * **Most common pelvis:** Gynaecoid (50%). * **Most common pelvis for OP position:** Anthropoid (initially), but **Persistent OP** is most classically linked to Android. * **Android Pelvis** is associated with the highest incidence of instrumental delivery (forceps/ventouse) and "Deep Transverse Arrest." * **Platypelloid Pelvis** is the rarest type and is associated with "Delayed Engagement."

Q: How is CPD (Cephalopelvic Disproportion) best assessed?

Clinical pelvic assessment. **Explanation:** Cephalopelvic Disproportion (CPD) occurs when there is a mismatch between the size of the fetal head and the maternal pelvic capacity, making vaginal delivery difficult or impossible. **Why Clinical Pelvic Assessment is the Correct Answer:** Clinical assessment remains the "gold standard" because CPD is a **functional diagnosis** that can often only be definitively confirmed during the trial of labor. Clinical pelvimetry (assessing the pelvic inlet, cavity, and outlet via vaginal examination) combined with the **Muller-Hillis maneuver** (to check for head engagement) allows for a dynamic evaluation. Unlike static imaging, clinical assessment accounts for the molding of the fetal head and the relaxation of pelvic ligaments during labor. **Why Other Options are Incorrect:** * **CT Scan & Radio pelvimetry (A & C):** While these provide precise bony measurements, they are poor predictors of actual labor outcomes. They cannot account for fetal head molding or the "give" of the pelvic joints. Furthermore, radiopelvimetry involves unnecessary ionizing radiation. * **Ultrasound (B):** USG is excellent for estimating fetal weight and head circumference (biometry), but it cannot accurately predict how that head will navigate the birth canal. **High-Yield Clinical Pearls for NEET-PG:** * **Muller-Hillis Maneuver:** The most common clinical method to assess CPD. If the head can be pushed into the pelvis without overriding the symphysis pubis, CPD is unlikely. * **Trial of Labor (TOL):** Indicated in mild to moderate degrees of suspected CPD (specifically in borderline contracted pelvis). It is contraindicated in major degrees of CPD. * **Diagnosis of Exclusion:** True CPD is often diagnosed retrospectively when labor fails to progress despite adequate uterine contractions (Power), favorable fetal position (Passenger), and no obvious pelvic deformity (Passage).

Q: Which of the following is a false statement regarding the anthropoid pelvis?

Ischial spines are prominent.. The **Anthropoid pelvis** is one of the four classic types of female pelves described by Caldwell and Moloy [1]. It is characterized by an oval-shaped inlet where the **anteroposterior (AP) diameter is greater than the transverse diameter**, resembling the pelvis of great apes [1]. ### Why the Correct Answer is Right: In an Anthropoid pelvis, the **ischial spines are typically blunt (not prominent)** [1]. Prominent or "encroaching" ischial spines are a hallmark feature of the **Android (masculine) pelvis**, which often leads to transverse arrest during labor. Therefore, the statement that ischial spines are prominent in an anthropoid pelvis is false. ### Analysis of Other Options: * **Option A:** True. The defining feature of the anthropoid pelvis is its long AP diameter and relatively narrow transverse diameter [1]. * **Option C:** True. The subpubic angle in an anthropoid pelvis is generally **wide or normal**, unlike the narrow, acute angle seen in the android pelvis [1]. * **Option D:** True. The sacrosciatic notch in the anthropoid pelvis is typically **large, shallow, and wide**, providing more posterior space [1]. ### NEET-PG High-Yield Pearls: * **Gynecoid:** Most common (50%); ideal for delivery; round inlet; wide subpubic angle. * **Android:** Heart-shaped inlet; prominent ischial spines; narrow subpubic angle; increased risk of instrumental delivery. * **Anthropoid:** Oval inlet (AP > Transverse); common in non-white races; associated with **occipito-posterior (OP) position** of the fetus [2]. * **Platypelloid:** Rarest; kidney-shaped inlet (Transverse > AP); flat pelvis.

Q: Arrest disorder is defined as the cessation of cervical dilatation in the active phase of labor of more than:

2 hours. **Explanation:** In modern obstetrics, labor abnormalities are categorized into **protraction disorders** (slow progress) and **arrest disorders** (complete cessation of progress). **1. Why Option D is Correct:** According to Friedman’s criteria, an **Arrest of Dilatation** is defined as the cessation of cervical dilatation for **2 hours or more** during the active phase of labor. For this diagnosis to be valid, the patient must have already entered the active phase (traditionally defined as ≥4 cm dilatation, though modern guidelines like Zhang’s often use 6 cm). This indicates a failure of the "power" (contractions), "passenger" (fetal size/position), or "passage" (pelvis). **2. Analysis of Incorrect Options:** * **Options A, B, and C:** These timeframes do not meet the diagnostic threshold for an arrest disorder. * **1.2 hours (Option B) and 1.5 hours (Option C)** are specific rates associated with **Protraction Disorders**. In the active phase, a primigravida should dilate at a rate of at least **1.2 cm/hr**, and a multigravida at **1.5 cm/hr**. If the rate is slower than this, it is "protraction," not "arrest." **3. NEET-PG High-Yield Pearls:** * **Arrest of Descent:** Failure of the fetal station to advance for **1 hour** or more. * **Active Phase definition:** While Friedman used 4 cm, the **WHO and ACOG** now define the start of the active phase at **6 cm** dilatation. * **Management:** Before diagnosing arrest in modern practice, ACOG recommends waiting for **4 hours** if contractions are adequate (measured via IUPC as >200 Montevideo units) or **6 hours** if contractions are inadequate and oxytocin is being used. * **Friedman’s Curve:** Remember that the active phase consists of the acceleration phase, phase of maximum slope, and deceleration phase. Arrest most commonly occurs during the phase of maximum slope.

Q: What is the commonest type of vertex presentation?

Left occipito transverse. **Explanation:** In vertex presentation, the position is determined by the relationship between the **occiput** (denominator) and the maternal pelvis. **Why Left Occipito-Transverse (LOT) is correct:** Statistically, **Left Occipito-Transverse (LOT)** is the most common initial position at the onset of labor. This is primarily due to the anatomical shape of the pelvic inlet. The transverse diameter of the pelvic inlet is wider than the anteroposterior diameter. Additionally, the presence of the sigmoid colon on the left side of the pelvis often pushes the occiput into a transverse or slightly anterior position. While many textbooks previously cited Left Occipito-Anterior (LOA) as the most common, modern obstetric studies and ultrasound data confirm that LOT is the most frequent starting position. **Analysis of Incorrect Options:** * **Left Occipito-Anterior (LOA):** This is the second most common position. It is often considered the "ideal" position for delivery, as the head is already partially rotated toward the symphysis pubis. * **Right Occipito-Anterior (ROA):** This occurs less frequently than LOA. The liver on the right side and the positioning of the descending colon on the left generally favor left-sided positions. * **Right Occipito-Posterior (ROP):** This is the most common **malposition** (not presentation). While it is the most frequent among posterior positions, it is significantly less common than LOT or LOA. **High-Yield Clinical Pearls for NEET-PG:** * **Most common position at onset of labor:** LOT. * **Most common malposition:** ROP (Right Occipito-Posterior). * **Most common mechanism of delivery:** The head usually enters in LOT, rotates 90° anteriorly during the second stage of labor to become Occipito-Anterior (OA) for delivery. * **Internal Rotation:** This occurs when the leading part (occiput) hits the pelvic floor and rotates toward the symphysis pubis.

Q: Deep transverse arrest is seen in all except?

Transverse lie. **Explanation:** **Deep Transverse Arrest (DTA)** occurs when the fetal head has descended to the level of the ischial spines (deep in the pelvic cavity) but fails to rotate from the occipito-transverse position to the occipito-anterior position. **Why "Transverse Lie" is the correct answer:** For DTA to occur, the fetus must be in a **longitudinal lie** with a cephalic presentation. In a **transverse lie**, the long axis of the fetus is perpendicular to the mother’s, and the presenting part is usually the shoulder. Since the head does not engage or descend into the pelvis in a transverse lie, the mechanism of "arrest of rotation" at the level of the spines is impossible. **Analysis of Incorrect Options:** * **Android Pelvis:** This is the most common cause of DTA. The narrow fore-pelvis and convergent side walls prevent the natural internal rotation of the fetal head. * **Epidural Analgesia:** It causes relaxation of the pelvic floor muscles (levator ani). Since the resistance of these muscles is essential for the fetal head to rotate, epidural anesthesia significantly increases the risk of DTA. * **Uterine Inertia:** Weak uterine contractions (secondary uterine inertia) provide insufficient force to push the fetal head against the pelvic floor, failing to facilitate internal rotation. **High-Yield Clinical Pearls for NEET-PG:** * **Definition:** Arrest of internal rotation at the level of the ischial spines for >1 hour. * **Pelvic Type:** Most common in **Android** and **Anthropoid** pelvis. * **Management:** If the pelvis is adequate and there is no CPD, it can be managed by **Manual Rotation** or **Kielland’s Forceps**. If these fail or CPD is present, **Cesarean Section** is the definitive treatment. * **Prerequisite:** The head must be engaged for DTA to be diagnosed.

Question 1

What is the most commonly encountered presenting part in a longitudinal lie?

Accepted Answer

Vertex

Answer

Brow

Answer

Face

Answer

Hand

Question 2

What is the common cause of retained placenta?

Accepted Answer

Atonic uterus

Answer

Constriction ring

Answer

Placenta accreta

Answer

Poor voluntary expulsive effort

Question 3

A 20-year-old G1P0 female at 40 weeks of gestation presents to the labor room with rupture of membranes and early onset of labor. She is extremely anxious with peripheral IV placement and begins to hyperventilate. If allowed to continue hyperventilation, what will occur?

Accepted Answer

Decreased maternal uterine artery flow

Answer

Decreased maternal arterial pH

Answer

Increased placental perfusion

Answer

Increased fetal arterial pH

Question 4

Cephalopelvic disproportion (CPD) in the absence of gross pelvic abnormality can be diagnosed by which of the following methods?

Accepted Answer

Trial of labor

Answer

Maternal height less than 158 cm

Answer

X-ray pelvimetry

Answer

Pelvic examination

Question 5

Persistent occipitoposterior presentation is common in which type of pelvis?

Accepted Answer

Android pelvis

Answer

Anthropoid pelvis

Answer

Gynaecoid pelvis

Answer

Platypelloid pelvis

Question 6

How is CPD (Cephalopelvic Disproportion) best assessed?

Accepted Answer

Clinical pelvic assessment

Answer

CT scan

Answer

Ultrasound

Answer

Radio pelvimetry

Question 7

Which of the following is a false statement regarding the anthropoid pelvis?

Accepted Answer

Ischial spines are prominent.

Answer

Anteroposterior diameter is greater than the transverse diameter.

Answer

Subpubic angle is wide.

Answer

Sacrosciatic notch is shallow and wide.

Question 8

Arrest disorder is defined as the cessation of cervical dilatation in the active phase of labor of more than:

Accepted Answer

2 hours

Answer

1 hour

Answer

1.2 hours

Answer

1.5 hours

Question 9

What is the commonest type of vertex presentation?

Accepted Answer

Left occipito transverse

Answer

Left occipito anterior

Answer

Right occipito anterior

Answer

Right occipito posterior

Question 10

Deep transverse arrest is seen in all except?

Accepted Answer

Transverse lie

Answer

Android pelvis

Answer

Epidural analgesia

Answer

Uterine inertia

Labor and Delivery — MCQs

Labor and Delivery — MCQs

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