Labor and Delivery — MCQs

Labor and Delivery Indian Medical PG Practice Questions and MCQs

Question 1031: The prostaglandin most commonly used at term for induction of labor is?

A. PGI2
B. PGE1
C. PGE2 (Correct Answer)
D. PGF2a

Explanation: ***PGE2*** - **Dinoprostone**, a synthetic form of **PGE2**, is widely used for **cervical ripening** and **labor induction** at term. - It softens and dilates the cervix, making it more favorable for the onset of uterine contractions. *PGI2* - Also known as **prostacyclin**, **PGI2** primarily acts as a **vasodilator** and **inhibitor of platelet aggregation**. - It is not commonly used for labor induction due to its different physiological effects. *PGE1* - **Misoprostol**, a synthetic **PGE1** analog, is also used for labor induction, but **PGE2** (dinoprostone) is generally considered the most commonly used prostaglandin at term for this purpose in many clinical settings. - **PGE1** can be associated with a higher risk of uterine hyperstimulation compared to PGE2. *PGF2a* - **PGF2a** (e.g., carboprost) is primarily used to manage **postpartum hemorrhage** due to its potent **uterotonic effects**. - While it causes uterine contractions, it is not the primary prostaglandin used for routine induction of labor at term.

Question 1032: Which nerve is most commonly injured in McRoberts maneuver?

A. Femoral nerve (Correct Answer)
B. Lumbosacral trunk
C. Obturator nerve
D. Pudendal nerve

Explanation: ***Femoral nerve*** - The **McRoberts maneuver** involves hyperflexion of the maternal hips, which can cause significant stretch on the maternal **lumbosacral plexus**. - Specifically, the **femoral nerve** (originating from L2-L4) can be compressed or stretched between the inguinal ligament and the hyperflexed thigh, leading to neuropathy. *Lumbosacral trunk* - While the **lumbosacral trunk** is part of the plexus, direct injury to its main body is less common than specific nerve branches during this maneuver. - The compression or stretch is often more focused on individual nerves passing through the pelvic outlet, such as the femoral nerve. *Obturator nerve* - The **obturator nerve** (L2-L4) passes through the obturator foramen and is less directly susceptible to injury from the hyperflexion of the hips in the McRoberts maneuver compared to the femoral nerve. - Its protected anatomical course makes it less vulnerable to the external forces applied during this maneuver. *Pudendal nerve* - The **pudendal nerve** (S2-S4) is typically associated with injury during vaginal delivery due to compression by the fetal head or forceps, not primarily from the hip hyperflexion in the McRoberts maneuver. - Its location deep within the perineum protects it from the mechanism of injury in the McRoberts maneuver.

Question 1033: What degree of perineal tear is indicated by an injury to the rectal mucosa?

A. First
B. Second
C. Third
D. Fourth (Correct Answer)

Explanation: ***Fourth*** - A **fourth-degree perineal tear** involves the perineal skin, vaginal mucosa, perineal muscles, external and internal anal sphincter, and the **rectal mucosa**. - This is the most severe type of tear, extending completely through the **anal sphincter complex** and into the rectum. *First* - A **first-degree tear** only involves the **perineal skin** and/or the **vaginal mucosa**. - It does not extend to the muscles or anal sphincter, let alone the rectal mucosa. *Second* - A **second-degree tear** involves the perineal skin, vaginal mucosa, and the **perineal muscles**, but not the anal sphincter. - While deeper than a first-degree tear, it does not reach the rectal mucosa. *Third* - A **third-degree tear** involves the perineal skin, vaginal mucosa, perineal muscles, and the **anal sphincter complex** (external and/or internal anal sphincter). - It does not extend to the rectal mucosa; if it did, it would be classified as a fourth-degree tear.

Question 1034: What are the potential complications associated with occipito posterior position during labor?

A. All of the options (Correct Answer)
B. Prolonged labor
C. Increased risk of cesarean delivery
D. Fetal distress

Explanation: ***All of the options*** Occipito posterior (OP) position is associated with **all three major complications**: 1. **Prolonged labor** - The OP position results in inefficient uterine contractions and suboptimal fetal head alignment with the maternal pelvis. This leads to a **protracted active phase** and **prolonged second stage**, with slower cervical dilation and descent. 2. **Increased risk of cesarean delivery** - Due to the combination of prolonged labor, arrest of descent, and failure of rotation, OP position carries a **2-3 times higher cesarean delivery rate** compared to occipito anterior positions. When spontaneous rotation fails or labor arrests, **operative intervention** becomes necessary. 3. **Fetal distress** - The prolonged labor, ineffective contractions, and increased compression on the fetal head can lead to **abnormal fetal heart rate patterns**, umbilical cord compression, and reduced placental perfusion, resulting in fetal compromise. **Why individual options are incomplete:** - While prolonged labor, increased cesarean risk, and fetal distress are each independently correct complications, selecting only one option would be incomplete - The question asks for "potential complications" (plural), and all three commonly occur together in OP presentations - The most comprehensive and accurate answer recognizes that **all of these complications** are associated with occipito posterior position

Question 1035: If the anal sphincter is injured, what degree of perineal tear does this represent?

A. First degree
B. Third degree (Correct Answer)
C. Fourth degree
D. Second degree

Explanation: ***Third degree*** - A third-degree perineal tear involves the **perineal skin**, **vaginal mucosa**, muscles of the perineal body, and extends to the **anal sphincter complex**. - These tears are categorized further into 3a (less than 50% external anal sphincter involvement), 3b (more than 50% external anal sphincter involvement), and 3c (both external and internal anal sphincter involvement). *First degree* - A first-degree tear involves only the **perineal skin** and/or the **vaginal mucosa**, without involving the deeper perineal muscles or anal sphincter. - These tears are usually **superficial** and often do not require suturing. *Fourth degree* - A fourth-degree tear is the most severe and involves the perineal skin, vaginal mucosa, perineal muscles, **anal sphincter complex**, and extends through the **rectal mucosa**. - This tear penetrates into the **lumen of the rectum**, carrying a higher risk of complications like rectovaginal fistula. *Second degree* - A second-degree tear involves the perineal skin, vaginal mucosa, and the **muscles of the perineal body**, but does not extend to the anal sphincter. - These tears typically require **suturing** to repair the muscle and fascial layers.

Question 1036: The pelvic inlet is usually considered to be contracted if its shortest anteroposterior diameter is less than 10 cm.

A. 10 cm (Correct Answer)
B. 12 cm
C. 14 cm
D. 8 cm

Explanation: ***10 cm*** - A pelvic inlet is clinically defined as **contracted** when its shortest anteroposterior diameter (the **obstetric conjugate**) is **less than 10 cm**. - This is the standard threshold used in obstetric practice to identify inlet contraction that may lead to **cephalopelvic disproportion**. - The normal obstetric conjugate measures approximately **10-11 cm**, so values below 10 cm indicate a contracted pelvis requiring careful assessment and management. *8 cm* - While 8 cm represents a **severely contracted pelvis** with significant risk of obstructed labor, it is not the defining threshold. - This measurement indicates **absolute contraction** where vaginal delivery is extremely difficult or impossible, but the standard definition of contraction begins at less than 10 cm. *12 cm* - A measurement of 12 cm for the obstetric conjugate is considered **normal to adequate**, well above the threshold for contraction. - This diameter would facilitate uncomplicated vaginal birth in most cases and poses no concern for inlet contraction. *14 cm* - An obstetric conjugate of 14 cm represents a **very capacious pelvis**, far exceeding normal measurements. - This measurement would pose no risk of cephalopelvic disproportion and indicates an unusually wide pelvic inlet.

Question 1037: Cord prolapse is most likely with -

A. Footling breech (Correct Answer)
B. Oligohydramnios
C. Vertex presentation with engaged head
D. Transverse lie

Explanation: ***Footling breech*** - **Footling breech** (one or both feet presenting) is the presentation with the **highest risk** of umbilical cord prolapse, with rates as high as **10-20%**. - The small, irregular presenting part (feet) **does not fill the pelvic inlet adequately**, leaving significant space for the umbilical cord to slip past, especially during rupture of membranes. - This is a **classic obstetric emergency** requiring immediate cesarean delivery when cord prolapse occurs. *Transverse lie* - **Transverse lie** also carries a significantly elevated risk of cord prolapse because the shoulder or arm presents, with **no presenting part engaging the pelvis**. - However, transverse lie is usually **identified before labor** and managed with planned cesarean section, often with **controlled membrane rupture**, which may reduce the actual incidence compared to footling breech where spontaneous rupture can occur. *Vertex presentation with engaged head* - An **engaged vertex** presentation provides excellent protection against cord prolapse because the fetal head **fills the pelvic inlet**, effectively blocking the cord from descending. - This is the **lowest risk** presentation for cord prolapse. *Oligohydramnios* - **Oligohydramnios** (reduced amniotic fluid) is **NOT** a recognized risk factor for cord prolapse. - In fact, reduced fluid volume may limit cord mobility. The related condition **polyhydramnios** (excessive fluid) is associated with increased cord prolapse risk due to increased cord mobility and space.

Question 1038: Which of the following represents the shortest transverse diameter of the fetal skull?

A. Biparietal diameter (BPD)
B. Bimastoid diameter (Correct Answer)
C. Bitemporal diameter
D. Suboccipitobregmatic diameter

Explanation: ***Bimastoid diameter*** - The **bimastoid diameter** is the shortest transverse diameter of the fetal skull, measuring approximately **7.5 cm** - It is the distance between the tips of the **mastoid processes** and is crucial for understanding the fetal head's fit through the maternal pelvis *Biparietal diameter (BPD)* - The biparietal diameter measures the distance between the two parietal eminences, typically around **9.5 cm** - It is a commonly used measurement in ultrasound to assess fetal growth and gestational age - This is a larger transverse diameter than the bimastoid *Bitemporal diameter* - The bitemporal diameter is measured between the furthest points on the coronal sutures, typically around **8.0 cm** - It is slightly larger than the bimastoid diameter but still considered a relatively narrow transverse measurement *Suboccipitobregmatic diameter* - The suboccipitobregmatic diameter is an **anteroposterior diameter**, not a transverse one, measuring from beneath the occipital bone to the center of the anterior fontanelle (bregma) - This diameter is approximately **9.5 cm** and is the optimal engaging diameter for vaginal birth when the head is well-flexed - This is not a transverse diameter and therefore cannot be the answer

Question 1039: What is the normal uterine blood flow at term?

A. 50-75 ml/min
B. 150-200 ml/min
C. 350-400 ml/min
D. 500-700 ml/min (Correct Answer)

Explanation: ***500-700 ml/min*** - At term, the uterus receives a substantial blood supply to meet the demands of the **growing fetus** and **placenta**. - This flow represents approximately **10-15% of the total cardiac output** in pregnant women. *50-75 ml/min* - This value is significantly **too low** for uterine blood flow at term. - Such a low flow would be insufficient to sustain fetal growth and development, leading to **fetal compromise**. *150-200 ml/min* - While an increase from non-pregnant levels, this value is still **below the normal range** for a full-term pregnancy. - It would not adequately perfuse the **placental bed** and transfer necessary nutrients and oxygen. *350-400 ml/min* - This range represents a considerable increase but is still somewhat **lower than the typical uterine blood flow at term**. - Uterine blood flow continues to increase throughout pregnancy, peaking in the **third trimester**.

Question 1040: Which layer of the uterus is primarily responsible for its contractile function during childbirth?

A. Perimetrium (outer layer)
B. Functional layer of endometrium
C. Myometrium (Correct Answer)
D. Basal layer of endometrium

Explanation: ***Myometrium*** - This **thickest layer** of the uterine wall is composed primarily of **smooth muscle cells**. - These muscle cells are responsible for generating the forceful **contractions** necessary to expel the fetus during childbirth. *Perimetrium (outer layer)* - The perimetrium is the **outermost serous layer** of the uterus, continuous with the broad ligament. - Its primary function is protective, reducing friction with surrounding organs; it does not contribute to uterine contractions. *Functional layer of endometrium* - This is the **superficial layer** of the endometrium that **sheds during menstruation** if pregnancy does not occur. - Its main roles are to provide a site for **implantation** and nourish an early embryo, not uterine contraction. *Basal layer of endometrium* - The basal layer is the **permanent layer** of the endometrium that remains after menstruation. - Its function is to **regenerate** the functional layer after each menstrual cycle, not to contract during labor.

Practice by Chapter

Physiology of Labor

Practice Questions

Stages of Labor and Normal Progression

Practice Questions

Fetal Monitoring Techniques

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Pain Management in Labor

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Induction and Augmentation of Labor

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Operative Delivery (Forceps and Vacuum)

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Cesarean Section: Indications and Techniques

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Dystocia and Abnormal Labor Patterns

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Obstetric Emergencies

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Postpartum Hemorrhage Management

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