Five forces decide whether a birth can happen. Set lie, presentation, attitude, position and station on a live pelvis and watch the three-letter code assemble itself. Then build a contraction pattern and let the Montevideo units tell you whether those powers are adequate or dangerous. Then settle the only question that actually proves labour has started — and score a cervix that is being asked to start one.
Choose a bench
Lie — fetal spine against maternal spine
Presentation — what enters the pelvis first
Attitude — how the head is held
Side of the maternal pelvis
Where the reference point points
0
Centimetres above (negative) or below (positive) the ischial spines. Zero means the widest diameter of the head has passed the pelvic inlet — engagement.
Challenge
4
60 s
60 mmHg
10 mmHg
If you had no catheter — palpation grade
Frequency is measured beginning-of-one to beginning-of-the-next, in minutes. Duration is beginning to end of the same contraction, in seconds. Montevideo units add every contraction’s peak-minus-baseline amplitude across a 10-minute window.
Part one — true labour or false labour?
Findings called correctly0 / 0
The score runs out of 13. The chapter’s thresholds are 8 or more — a vaginal birth about as likely as with spontaneous labour — and 6 or less, which calls for cervical ripening before oxytocin.
Set the passengerThe code assembles as you choose
LOAleft occiput anterior
Longitudinal, cephalic, well flexed
Build a contraction patternThen read the Montevideo units
Frequency
2.5
min apart
Duration
60
seconds
Resting tone
10
mmHg
Adequate labour
Contractions that are too frequent are as dangerous as contractions that are too weak, because the placenta refills only between them. Tachysystole is more than five contractions in 10 minutes averaged over a 30-minute window.
Membranes have rupturedA gush of clear fluid, 30 seconds ago
Part two. Your patient is 4 cm, contracting every 5 minutes, and reports a sudden gush of warm clear fluid. What is your first action?
Confirming rupture, and reading the fluid
Pooling in the posterior fornix, a nitrazine strip turning blue-green, ferning on a dried slide, or a commercial placental protein assay. Amniotic fluid pH is about 6.5 to 7.5 against a vaginal pH of 4.5 to 5.5 — but blood, semen and infection all raise vaginal pH and give false positives.
What colour is the fluid?
The clock starts now. The risk of intra-amniotic infection climbs after about 18 to 24 hours of ruptured membranes, and vaginal examinations are kept to the minimum necessary from this point because each one imports organisms.
Bishop score 0 of 13Choose the five cervical findings
Component
Finding
Points
Waiting
Oxytocin is delayed 30 to 60 minutes after a dinoprostone insert is removed, and about 4 hours after a misoprostol dose. The dinoprostone insert is removable, which is its advantage if tachysystole develops.