Highly Confused

[Babycatcher2B]

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So I am studying for Step II and doing USMLE World questions. I came across the following scenario:

28 year old primigravida presents in active labor. Over four hours, progresses from 3 cm to 8 cm and -1 to +1 station. 6 hours later, is at the same dilation and descent. Baby is in LOA. External tocometer read contractions every 3 mins lasting 50 seconds each. Internal pelvic assesment show prominent ischial spines. Fetal heart tracing shows HR at 140s with frequent accelerations. Ultrasound at 37 weeks shows average size fetus. Most appropriate next step in management?

Answer: C-section

It is obvious that the patient is in arrest of dilation and descent. It seems that the contractions are adequate. However, what is confusing me is that the baby is at +1 station, which means the largest part of the head (and fetus) has successfully trasversed the widest part of the pelvis. I see the question states that their are prominent ischial spines. The question is: is it still possible to have pelvic disproption even after descending past 0 station. My answer to the question was to start IV oxytoxin (even though the contractions seem adequate, however you cannot be 100% sure until you insert an internal monitor). Any thoughts?

 

[Global Disrobal]

Here is my opinion:

The key phrase in this question is the "prominent ischial spines." This generally indicates an android pelvis (from clinical pelvimetry) or a contracted pelvis. This can result in pelvic dystocia leading to need for a cesarean delivery.

If you keep it as simple as the 3 "P's" in your head, the answer would make sense. In this case, "power" and "passenger" are favorable, but "passage" is inadequate.

Another option (if the ischial spine comment was ommitted) would be to give Oxytocin, but with contractions every 3 minutes, its unlikely that this would do much.

Hope this helps. Good luck on the test.

 

[Trillgirl]

USMLE questions, as you know, are usually poorly written and they are trying to get you to answer the question as they want it answered - not necessarily the "right" answer.

It's a stupid question.

First, if the baby is truly in +1 station, the presenting part of the head should be past the ischial spines (0 = ischial spines)... Global is right, though. The passage is probably hinting at a non-gynecoid pelvis.

But more importantly... what OB worth their salt would let a patient sit at 8 cm for SIX hours without an IUPC to see if the contractions were adequate? The patient fell off the ole Friedman curve ages ago.

Cut.