A 26-year-old primigravid woman at 39 weeks' gestation is admitted to the hospital in active labor. Pregnancy was complicated by mild oligohydramnios detected a week ago, which was managed with hydration. Her pulse is 92/min, respirations are 18/min, and blood pressure is 134/76 mm Hg. Pelvic examination shows 100% cervical effacement and 10 cm cervical dilation; the vertex is at 0 station. Cardiotocography is shown. Which of the following is the most appropriate next step in management?

Maternal repositioning and oxygen administration

A 27-year old primigravid woman at 37 weeks' gestation comes to the emergency department because of frequent contractions for 4 hours. Her pregnancy has been complicated by hyperemesis gravidarum which subsided in the second trimester. The contractions occur every 10–15 minutes and have been increasing in intensity and duration since onset. Her temperature is 37.1°C (98.8°F), pulse is 110/min, and blood pressure is 140/85 mm Hg. Uterine contractions are felt on palpation. Pelvic examination shows clear fluid in the vagina. The cervix is 50% effaced and 3 cm dilated. After 4 hours the cervix is 80% effaced and 6 cm dilated. Pelvic examination is inconclusive for the position of the fetal head. The fetal heart rate is reassuring. Which of the following is the most appropriate next step?

Perform external cephalic version

Perform Mauriceau-Smellie-Veit maneuver

A 26-year-old G1P0 woman at 40 weeks estimated gestational age presents after experiencing labor pains. Pregnancy has been uncomplicated so far. Rupture of membranes occurs, and a transvaginal delivery is performed under epidural anesthesia, and the baby is delivered alive and healthy. The patient voids a few hours after the delivery and complains of mild irritation at the injection site on her back. On the second day, she complains of a severe headache over the back of her head. The headache is associated with pain and stiffness in the neck. Her headache is aggravated by sitting up or standing and relieved by lying down. The pain is relieved slightly by acetaminophen and ibuprofen. The patient is afebrile. Her vital signs include: pulse 100/min, respiratory rate 18/min, and blood pressure 128/84 mm Hg. Which of the following statements is the most accurate regarding this patient’s condition?

This patient’s condition can resolve on its own

A blockage of CSF is the cause of this patient’s headache

An infection is present at the epidural injection site

Excessive bed rest will worsen this patient’s condition

Immediate intervention is required

A 28-year-old primigravid woman at 36 weeks' gestation comes to the emergency department for 2 hours of contractions. Her pregnancy has been uncomplicated. The contractions occur once every 20–30 minutes, last less than 30 seconds, and have been consistent in intensity and duration since onset. During that time there has been an increase in fetal movements. Her temperature is 37.1°C (98.8°F), pulse is 98/min, and blood pressure is 104/76 mm Hg. Pelvic examination shows clear cervical mucus and a firm uterus consistent in size with a 36-week gestation. The cervix is 0% effaced and undilated; the vertex is at -3 station. The fetal heart rate is reassuring. After an hour of monitoring in the emergency department, the character of the contractions and pelvic examination findings remain unchanged. Which of the following is the most appropriate next step?

Admit for continuous monitoring

Offer local or regional anesthesia

A 30-year-old woman, gravida 2, para 1, at 38 weeks' gestation comes to the hospital for regular, painful contractions that have been increasing in frequency. Her pregnancy has been complicated by gestational diabetes treated with insulin. Pelvic examination shows the cervix is 50% effaced and 4 cm dilated; the vertex is at -1 station. Ultrasonography shows no abnormalities. A tocometer and Doppler fetal heart monitor are placed on the patient's abdomen. The fetal heart rate monitoring strip shows a baseline heart rate of 145/min with a variability of ≥ 15/min. Within a 20-minute recording, there are 7 uterine contractions, 4 accelerations, and 3 decelerations that have a nadir occurring within half a minute. The decelerations occur at differing intervals relative to the contractions. Which of the following is the most appropriate next step in the management of this patient?

Placement of fetal scalp electrode

Second stage of labor for USMLE Step 3: High-Yield OB/GYN Lessons

Second Stage of Labor - The Final Push

Definition: Full cervical dilation (10 cm) to delivery of the infant.
Duration: Varies by parity and anesthesia.
- Nulliparous: ~50 min (up to 3 hours with epidural).
- Multiparous: ~20 min (up to 2 hours with epidural).
Cardinal Movements: Fetal descent through the pelvis.

⭐ Persistent occiput posterior (OP) is the most common malposition, associated with a prolonged second stage, intense back pain, and higher rates of operative delivery.

Cardinal Movements of Labor

Cardinal Movements - Baby's Grand Exit

Cardinal movements of labor

Sequential fetal movements through the maternal pelvis, crucial for successful vaginal delivery.

📌 Every Darn Fool In Egypt Eats Raw Eggs
- Engagement: Biparietal diameter passes the pelvic inlet.
- Descent: Downward passage through the pelvis.
- Flexion: Fetal chin tucks to chest.
- Internal Rotation: Occiput rotates towards the pubic symphysis.
- Extension: Head extends as it passes under the pubic symphysis.
- External Rotation (Restitution): Head realigns with the shoulders.
- Expulsion: Delivery of shoulders and body.

⭐ Asynclitism, where the fetal head is misaligned with the maternal pelvis (sagittal suture not centered), can halt labor progress.

Management & Monitoring - Coaching the Delivery

Pushing Technique:
- Encourage spontaneous, open-glottis pushing with contractions.
- Avoid sustained, closed-glottis (Valsalva) pushing to ↓ risk of fetal acidosis & perineal trauma.
Maternal Positioning:
- Upright or lateral positions (e.g., squatting, hands-and-knees) are preferred over supine.
- Helps optimize pelvic diameters and may shorten the stage.
Fetal Monitoring:
- Continuous or intermittent auscultation per ACOG guidelines.

⭐ The Ferguson reflex-pressure on the cervix and vaginal walls-triggers oxytocin release, strengthening contractions and the maternal urge to push.

Labor Arrest & Dystocia - When Things Get Stuck

Arrest of Descent: Defined by the American College of Obstetricians and Gynecologists (ACOG) as no fetal descent after specific durations of pushing in the second stage of labor.
Diagnostic Criteria (Time spent pushing with no descent):
- Nulliparous: ≥4 hours with an epidural, ≥3 hours without.
- Multiparous: ≥3 hours with an epidural, ≥2 hours without.

⭐ Always evaluate the "3 Ps" (Power, Passenger, Passage) to determine the etiology before intervening. This is a classic exam concept.

Etiology (The 3 Ps):
- Power: Inadequate uterine contractions (use IUPC to assess).
- Passenger: Fetal malposition (e.g., occiput posterior, asynclitism) or macrosomia.
- Passage: Cephalopelvic disproportion (CPD).

High‑Yield Points - ⚡ Biggest Takeaways

Begins at full cervical dilation (10 cm) and ends with delivery of the infant.

Duration is longer in nulliparous women and with epidural anesthesia; prolonged if >3 hours (nulliparous) or >2 hours (multiparous) with an epidural.

Key cardinal movements are internal rotation to pass the ischial spines and extension of the fetal head.

Progress is monitored by assessing fetal station (descent relative to the ischial spines).

Arrest of descent is a major indication for operative vaginal delivery (forceps/vacuum) or cesarean section.

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