Cardiotocograph: the tracing behind the NST · tap to expand
Ultrasound: four of the five BPP points live here · tap to expand
Placenta: chronic insufficiency drains the fluid · tap to expand
Fetal profile: movement, tone, breathing are watched here · tap to expand
🤳
Is the Baby Okay? The Fetal Surveillance Ladder
A patient's water breaks at 30 weeks. Every test you order now answers one question: deliver, or wait? Climb the ladder the boards climb: NST first, BPP when the NST won't commit, delivery when the score says stop waiting.
A 29-year-old G2P1 at 30 weeks is on day 2 after confirmed rupture of membranes, receiving latency antibiotics and betamethasone. Today's NST shows no accelerations over 40 minutes even after vibroacoustic stimulation. She is afebrile, non-tender, and the fetal heart baseline is 140 with moderate variability.
What is the single best next step?
Immediate cesarean delivery
Biophysical profile
Repeat the NST tomorrow
Start oxytocin induction
Start Here
Confirm the Rupture, Then Read the Screen
Name the leak, then start the first rung: the nonstress test. It is a screen, not a verdict.
Spot the leak
Fluid gush before 37 weeks with pooling, ferning, and a positive nitrazine test on a sterile speculum exam = preterm premature rupture of membranes (PPROM). Confirm with speculum only. No digital exam, because a finger seeds infection and shortens latency.
Four terms the boards blur together. Tap each to separate them.
PPROM: rupture before term, before contractions
Membranes rupture before 37 weeks and before labor starts. The infection clock is running. This is the setup for the whole surveillance ladder.
PROM: rupture at term, before contractions
Same "before labor" idea, but at or after 37 weeks. The P you drop is "preterm." Management leans toward delivery because the fetus is mature.
Prolonged ROM: the clock, not the calendar
Membranes have been ruptured more than 18 hours regardless of gestational age. It is a risk marker for infection, not a gestational stage.
Preterm labor: contractions, cervix changing
Regular contractions with cervical change before 37 weeks. Membranes may still be intact. Different problem, different first move (tocolysis considerations, steroids), and it can coexist with PPROM.
Rung 1: the nonstress test (NST)
Reactive = at least 2 accelerations of ≥15 bpm lasting ≥15 seconds within 20 minutes (the 15x15 rule). Before 32 weeks, immaturity earns the softer 10x10 rule (10 bpm for 10 seconds).
An acceleration means an intact autonomic nervous system driving a healthy heart. Reactive is reassuring.
⚡THE PUNCH: A nonreactive NST is a screening failure, not a diagnosis. The most common reason a fetus won't accelerate is that it is asleep. You do not buy an operating room off a screen. You climb to the next rung.
⚠
Digital exam in PPROM without labor
If she is not in labor, keep your fingers out. Every digital exam drags bacteria up the canal and shortens the latency period. Sterile speculum confirms the rupture; the finger is the trap.
Interactive
NST Strip Judge
Stylized tracings, not real strips. Count the accelerations, then call it reactive or nonreactive before you reveal the logic.
When the screen fails, what next?
First, wake the fetus: vibroacoustic stimulation or simply extend the strip to catch a sleep cycle.
Still nonreactive? Climb to the biophysical profile.
Never go straight from a nonreactive NST to cesarean. The false-positive rate is high, and the usual culprit is a nap.
Signature Game
Build the Biophysical Profile
Five components, two points each, all-or-nothing. Toggle each tile, watch the total and the management band recolor live, then read what the score forces you to do.
The Five-Point Verdict
NST plus four ultrasound windows. A component either earns its 2 points or earns 0. There is no partial credit.
0/10
Toggle tiles to score
Each tile you switch on adds 2. The band and the next move update as you go.
TEST THE BABY ON MY FLOOR
A dumb five-word hook for the components: Tone, The Breathing, Movement, Monitor (NST), Fluid. Five words, five points.
8 IS GREAT, 6 IS A MAYBE, 4 GET IT OUT
8 to 10 = reassuring. 6 = equivocal, repeat or deliver depending on maturity. 4 or less = deliver soon. 0 to 2 = deliver now.
FLUID IS THE MEMORY
Breathing, movement, tone, and NST all tell you about hypoxia right now. Amniotic fluid tells you about hypoxia over days. Low fluid with normal acute markers is a chronic story, not a code.
The shortcut: modified BPP
When you don't need the full five, the modified BPP = NST + amniotic fluid index. It pairs the best acute marker (NST) with the best chronic marker (fluid). Reassuring modified BPP buys time; an abnormal one sends you to the full profile.
Put It Together
Gestational Age Fork and the Delivery Triggers
Slide the weeks. Watch the PPROM plan redraw. Then walk the decision tree, guessing each branch before it opens.
30 weeks
2224283437
🚨Red overlay, any age: chorioamnionitis, placental abruption, or non-reassuring fetal status = deliver now. These jump the calendar. Fever + fundal tenderness + fetal tachycardia in PPROM is clinical chorioamnionitis: broad-spectrum antibiotics and delivery, do not stall for a score.
Decision tree: guess before each reveal.
Rung 1 · NST is nonreactive at 30 weeks on expectant PPROM. Next?
Wake the fetus, then image. Nonreactive usually means sleep. Vibroacoustic stimulation or an extended strip, then a biophysical profile. A screen never earns an OR by itself.
Rung 2 · BPP comes back 6/10 in a preterm fetus. Next?
6 is the equivocal band. If preterm, repeat within 24 hours and watch closely. If term, that same 6 tips you toward delivery. The number is read against the calendar.
Rung 3 · BPP shows low fluid but normal breathing, movement, tone, and NST. What does it mean?
Fluid is the memory. Normal acute markers with low fluid is a slow, days-long story of placental insufficiency, not a minute-to-minute emergency. This is a delivery-timing conversation, not a resuscitation.
Rung 4 · BPP is 2/10, or fever + fundal tenderness + fetal tachycardia appears. Next?
Hostile uterus, stop waiting. A very low BPP or clinical chorioamnionitis overrides the 34-week calendar. Deliver; add broad-spectrum antibiotics for chorio. The environment is now more dangerous than prematurity.
SCREEN FAILS, DON'T CUT
Nonreactive NST is the classic board trap. The move is almost never cesarean. It is stim, extend, then BPP.
STEROIDS EVEN IF YOU'RE WAITING
Between 24 and 34 weeks, give betamethasone even when delivery isn't planned today. The lungs need the head start you can't take back.
Prove It
Board Walkthrough
Original vignette bank, 5 dealt per round, answer choices shuffled, never-repeat within a round. Tap a wrong answer first to see why it almost works, then read the glowing clues.
Medically reviewed by Kaitlyn Cocuzzo, MD and Fatima Ali, DO · Last updated July 2, 2026 at 9:08 AM ET
Bone Wizardry is an independent educational resource for visual learning in the medical sciences. It is not affiliated with, endorsed by, or sponsored by any licensing or examination board, contains no real or recalled examination questions, and does not guarantee any educational or examination outcome.
