Spontaneous Vaginal Delivery
Introduction
Labour is a series of repetititive uterine contractions, lasting 30-60 seconds, associated with progressive cervical dilation and effacement of the cervix. Term is 37-42 weeks, with preterm before and postterm after.
Can be associated with "bloody show", diarrhea (because of prostaglandin), or rupture of membranes.
Care begins with assessment and admission to hospital. As this can be an uncertain and fearful time, a caring attitude of the admitting health care professional is critical to set the stage for what is to come.
Assessment of progress should be done with a sterile gloved hand. In areas where perinatal infection rates are high, soaking the gloved hand in 0.25% chlorhexidine solution can be helpful.
Supplies Required
coming soon
Evaluating Labour
- history
- physical exam
- fetal monitoring
History
When documenting obstetrical history, use bullets and acronyms as appropriate. Consise is important.
birth history
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medications past medical history family history
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Right Now
group B strep status contractions
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ruptured membranes |
Physical Exam
Vitals of mother and baby
- fetal heart rate (doptone, NST)
Abdominal exam
- symphysis to fundal height
Leopold's maneuvers to determine position of fetus
Presentation
PV exam
0 |
1 |
2 |
3 |
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dilation |
closed |
1-2 |
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effacement |
0-30 |
40-50 |
60-70 |
80+ |
station |
-3 |
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consistency |
firm |
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position |
post |
Sterile speculum exam
- sterile q-tip, with nitrosine or ferning under microscope
Assessing Progress in Labour
First ensure labour is occurring
Progress as per primip/multip
- PV exam q2hours: more frequent if pain is substantial,
Fetal Monitoring
Normal HR 120-180
Variability changes in short term/long term
Accelerations: increases of 15 bpm x 15 sec above baseline
Decelerations:
- depends on...
can use tophometer or scalp monitoring (more accurate; used if worrying FHR, multiples)
Non stress test
As food will not pass through the gut during labour, food should be avoided, especially if general anesthetics are possibly to be used. However, low-fibre, low-fat meals or drinks likely pose little hazard, and may in fact prevent ketoacidosis. (O'Sullivan et al, 2009).
The following should be monitored during the first stage:
- pulse, temperature, and blood pressure every 2 hours
- assess frequency, strength, and intensity of uterine contractions
- monitor fetal heart rate every 15 minutes
- assess cervical dilatation every 4 hours to determine progress and descent of presenting part
- discuss ongoing analgesic needs
- determine position of head
Progress is again dependent on the three P's:
- power of contractions
- passage
- passenger: flexion or position can be enhanced using manual, vacuum, or forceps technique
Six Cardinal Mechanisms of Labour
Descent
- occurs prior to onset and then throughout labour, with other mechanisms superimposed on it
- occurs at greater rate during latter part of 1st stage and 2nd stage
Flexion
- present before labour to some degree due to natural muscle tone
- further encouraged during labour by resistance from cervix, walls of pelvis, and pelvic floor
- optimizes presenting diameter of head
Internal Rotation
- head enters transversely and then rotates so that occiput is turned towards symphysis pubis (OA, occiput anterior position)
- 20% of the time, the head rotates OP, occiput posterior, though at least 75% of fetuses will rotate back as labour progresses
Extension
- to follow the path of the vagina, as the head moves under the symphysis it needs to move from flexion to extension
- make sure there's not too much extension
- crowning - when the largest diameter of the head is encircled by the vaginal opening, occurs during extension
External Rotation/Restitution
- the delivered head now rotates back to the transverse position, as it originally was, realigning the head with the back and shoulders
Delivery/Expulsion
- as descent continues, anterior shoulder delivers under the symphysis pubis, followed by the posterior shoulder. The rest of the body quickly follows
Stage III
- delivery of baby and placenta; duration avg 5-10 min; range 0-30 min
- signs of placental separation:
- gush of blood from vagina
- ubbilical cord lengthening
- fundus of uterus moves up into abdomen
- uterus becomes firm and globular
- watch closely for postpartum hemorrhage
- inspect cervix, vagina, and perineum for lacerations and repair if necessary
- inspect placenta to ensure complete removal
Used during delivery
IV oxytocin is effective within 30-60 seconds
IM oxytocin is effective in 3-4 minutes.
Its duration of action is 5-15 mins.
hyperstimulation
fetal heart decel
hyponatremia occurs really only after dose of 40 mIU/min
Perinatal Bloodwork
- platelets
- RBC
- WBC
- manual differential
- other
- blood chemistries
Platelets
Platelet normally 150-400 x 109/L
Platelets are acute phase reactants, so a low count may suggesr sepsis or coagulopathy (ie pregnancy-induced hypertension in HELLP syndrome - hemolysis, elevated liver enzymes, low platelets)
<150 warrants mention and <100 is concerning; if platelets are less than 40x 109/L, spontaneous bleeding can occur, ie into the neonatal cerebral ventricles.
A count higher than 400 may indicated fungal infection in those susecptible
Hemoglobin
Hgb
adult females 120-145 g/L
neonates 160-200 g/L
In a situation of acute hemorrhage, the hgb will be unchanged. It will take 3-12 h for fluid volume to be replaced and hgb to drop
RBC, hematocrit, MCV, MCH, MCHC not as helpful acutely, but can assist with explanation of type of anemia.
White Blood Cell Count
WBC
women in labour have a higher WBC (10-21) due to the stress reaction
sepsis in labour can lead to 16-24
Neonates
- first 24 hours of life: up to 24x109 (stress reaction)
- 24-48h: 12-20
- after 48h: 4-12
- a corrected WBC neonatal count is the manual count of WBCs; an automated count may include nucleated RBCs due to the stress of birth
Manual Differential
A manual differential will give band count.
An infection will lead to neutrophils
Neutrophils
The more immature cells circulating, the more concerning the situation.
If there is a major blood loss
Other
Kleihauer test
indicated percentage of fetal RBCs in the mother's circulation. Normal 0-0.2%.
If mother needs WinRho therapy, and the Kleihauer result exceeds 0.2%, the dosage of WinRho must be adjusted upwards.
It is normally only requested in Rh-negative mothers, but also can be ordered on any mother in whom fetal-maternal hemorrhage is suspected (ie abruption).
ABO/Rh type
read carefully to see whether it refers to mother's blood or cord (CD) blood
DAT Direct Antibody Test
measures presence of antibodies
WinRho A/D suggests antibodies have been triggered by WinRho, not infant.
A positive result in an infant suggests increased risk of hemolytic hyperbilirubinemia.
Blood Chemistries
Cord Gases
arterial - reflects neonate's status at moment of delivery
venous - reflects mother's status at that time, so is almost always more normal than the arterial result.
pH arterial:
- normal adult: 7.35-7.45
- infant at birth: >7.2
- neonate: 7.32-7.42
pCO2 arterial:
- normal adult: ~40 mmHg
- infant at birth: <60 mmHg
- neonate: 30-45 mmHg
BE
HCO3
pO2: always very low in a cord arterial sample
- irrelevant in a cpillary heel stick sample
Bilirubin
- total = conjugated plus unconjugated
- babies almost always have unconjugated
protein
- total protein = albumin, immunoglobulins, etc
- TProt correlates with albumin
- albumin transports unconjugated bilirubin, preventing it from crossing the BBB
- a low albumin leads to increased risk of kernicterus, even though bilirubin levels can be normal
- albumin levels will be low in neonates who are preterm, small for gestational age, or otherwise malnourished
ESR and CRP
- non-specific; may be elevated in hemolysis or injury
- CRP faster than ESR
Resources and References
O'Sullivan G et al. 2009. Effect of food intake during labour on obstetric outcome: randomised controlled trial. BMJ. 338:b784
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