Which woman is the best candidate for a trial of labor after cesarean (TOLAC)?

Correct Answer: B

Rationale: The correct answer is B: A 21-year-old gravida 2, para 1 with one previous low-transverse cesarean section for CPD. This candidate is the best choice for a trial of labor after cesarean (TOLAC) because a low-transverse incision has the lowest risk of uterine rupture during labor compared to classical, T-shaped, or vertical incisions. Additionally, the indication for the previous cesarean section being cephalopelvic disproportion (CPD) suggests that the pelvis may have been the limiting factor in the previous delivery, making a TOLAC a reasonable option. The other choices have higher risks of uterine rupture (classical incision, T-shaped incision) or indications that may increase the likelihood of complications during TOLAC (prematurity, late decelerations).

Correct Answer: A

Rationale: The active phase of labor begins at 6 cm dilation according to ACOG guidelines. At this point, the cervix is significantly dilated, signaling the transition to active labor. This stage is crucial as it signifies the acceleration of labor progress and typically involves stronger contractions leading to efficient cervical dilation. Choices B, C, and D are incorrect as they do not align with the established criteria for the active phase of labor. Choice B (3 cm) is too early for active labor, choice C (5 cm) is close but not quite at the threshold for active labor, and choice D (10 cm) is actually the full dilation stage, not the beginning of active labor. Hence, choice A (6 cm) is the correct answer.

Correct Answer: C

Rationale: The correct answer is C because the expected length of the third stage of labor, which is the delivery of the placenta, is typically around 1 hour for a multiparous person (someone who has given birth before) and around 2 hours for a nulliparous person (someone who is giving birth for the first time). This is based on the normal physiological process of the uterus contracting to expel the placenta. Choice A and B are incorrect as they provide specific time limits that are not generally applicable to all individuals. Choice D is incorrect as it suggests longer durations which are beyond the typical range for the third stage of labor.

Correct Answer: D

Rationale: The correct answer is D because during labor, progesterone levels decrease, estrogen levels increase, and oxytocin plays a key role in initiating contractions. Progesterone inhibits contractions, so its decrease is necessary for labor to start. Estrogen helps stimulate uterine contractions. Oxytocin, released from the brain, triggers and enhances contractions. Option A is incorrect because an absence of oxytocin would not initiate labor. Option B is incorrect because increased progesterone would inhibit labor. Option C is incorrect because oxytocin is needed to initiate labor.

Correct Answer: E

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.