Assisted Vaginal Delivery Indications
The correct answer is C: Category III fetal heart rate tracing is an indication for assisted vaginal delivery when the fetal head is adequately descended and all prerequisites are met. 1
Understanding the Question
This question asks about indications for operative vaginal delivery (forceps or vacuum extraction), not contraindications. Let me analyze each option:
Option C: Category III Fetal Heart Rate Tracing (CORRECT)
Category II-III fetal heart rate abnormalities require expedited delivery to prevent further fetal compromise, and operative vaginal delivery is the preferred method when feasible. 1
- Late decelerations with minimal variability indicate possible fetal hypoxia or acidemia, requiring discontinuation of oxytocin and expedited delivery via operative vaginal or cesarean delivery 1
- When the fetal head is adequately descended (typically +2 station or lower), operative vaginal delivery is safer and faster than cesarean section for achieving expedited delivery 1
- Accepted indications for forceps-assisted delivery include suspected fetal distress, which encompasses Category III tracings 2
Option A: Suspected Cephalopelvic Disproportion (INCORRECT)
Cephalopelvic disproportion is an absolute contraindication to operative vaginal delivery, not an indication. 3
- When cephalopelvic disproportion is confirmed, cesarean delivery is mandatory because vaginal delivery is "unlikely to be achievable, let alone safely" 3
- The risks of maternal and fetal damage are too great to attempt vaginal delivery when cephalopelvic disproportion is present 3
- A complete cephalopelvimetric evaluation is vital before considering operative vaginal delivery, and cephalopelvic disproportion represents a clear contraindication 4
Option B: Brow Presentation (INCORRECT)
Brow presentation is a malpresentation that represents a contraindication to operative vaginal delivery. 4
- Fetal malpresentation, including brow presentation, is a related factor to cephalopelvic disproportion and cannot be delivered vaginally 4
- Cesarean section is the safest and most prudent option when there is evidence of malpresentation that cannot be delivered vaginally 4
- Attempting operative vaginal delivery with brow presentation is futile and dangerous, as the malpresentation cannot pass through the pelvis 4
Option D: Prolonged First Stage of Labor (INCORRECT)
Prolonged first stage of labor is NOT an indication for operative vaginal delivery because the cervix is not yet fully dilated. 2
- Operative vaginal delivery can only be performed at full cervical dilation (10 cm) in the second stage of labor 2
- Prolonged first stage refers to abnormal labor progression before reaching 10 cm dilation 5
- Management of prolonged first stage involves oxytocin augmentation (if no cephalopelvic disproportion), amniotomy, or cesarean delivery—not operative vaginal delivery 3
Additional Valid Indications for Operative Vaginal Delivery
Beyond Category III fetal heart rate tracings, other accepted indications include:
- Prolonged second stage of labor (not first stage), which occurs after full dilation 2
- Maternal medical conditions that benefit from shortened second stage, such as cardiac disease or severe hypertension 2
- Maternal exhaustion in the second stage with adequate fetal descent 1
Critical Prerequisites
Before attempting operative vaginal delivery, all of the following must be confirmed:
- Full cervical dilation (10 cm) 2
- Ruptured membranes 2
- Engaged fetal head with adequate descent (typically +2 station or lower) 1
- Known fetal position 2
- Absence of cephalopelvic disproportion 3, 4
- Adequate maternal pelvis 2
- Vertex presentation (not brow, face, or breech) 4
Clinical Pitfall to Avoid
The most common error is confusing prolonged first stage with prolonged second stage of labor. Only the latter is an indication for operative vaginal delivery, as the cervix must be fully dilated before instruments can be applied 2. Attempting operative delivery before full dilation risks severe cervical lacerations and maternal hemorrhage.