Chapter 1 - Normal Pregnancy Flashcards
Obstetric physical examination
Inspection, palpitation and auscultation
Inspection:
- size of distension
- asymmetry
- fetal movements
- cutaneous signs: linea nigra, striae gravidarum, striae albicans
Palpitation:
- symphysis fundal height (measured >20weeks)
- estimate no of fetuses (no of poles)
- fetal lie (longitudinal, oblique or transverse)
- presentation (cephalic, breech or other)
- amniotic fluid vol (tense + impalpable fetal parts, normal or compact abdomen with too easily palpated fetal parts)
Auscultation
- heart heard best at the anterior shoulder
- Doppler US from 12 weeks
- fetal stethoscope from 24 weeks
General exam
- BMI
- BP
- heart and lung auscultation (flow murmurs normal)
- thyroid gland
- breast
- skeletal abnormalities
When does the uterus become palpable?
12 weeks gestation
When does the uterus reach the umbilicus?
20 weeks
When does the uterus reach the xiphi sternum?
36 weeks
When is symphysis fundal height most efficacious?
In detecting small for gestation (40-60% small for dates fetuses can be detected).
It is less efficacious in detecting large for dates fetuses
How do you measure symphysis fundal height?
Tape measured from the highest point of the fund us to the upper margin of the symphysis pubis
How do you estimate appropriate fetal growth on examination?
Symphysis fundal height
- appropriate growth is number of weeks:
+/- 2cm from 20w to 36w
+/- 3cm between 36w-40w
+/- 4cm at 40w
When does engagement usually occur?
In nulliparous, engagement usually occurs at 37weeks
Afrocarribeans may occur later, even as late as labour
In multiparous it may not occur until labour
Rare causes of non engagement must always be considered and investigated with US.
- placenta previa
- fetal abnormality
Describe the assessment of engagement
5/5 palpable = head completely above the pelvic brim
2/5 palpable = engaged
- sinciput (forehead) just felt, occiput felt
More easily the head is felt the less engaged it is
Breech can be mistaken for a deeply engaged head
Describe fetal positions
Insert pic
OA normal
Differences between female and male pelvis
- female pelvis is broader with more slender bones
- females are oval shaped transversely with the widest part forward rather than heart shaped in men
- females are wider with a larger outlet
Pelvic anatomy
Label pic
Insert pic
Describe the 4 pelvic shapes
1) Gynaecoid - classical female pelvis with the inlet transversely oval
2) Anthropoid - long and narrow, oval shaped pelvis due to the assimilation of the sacral body to the 5th lumbar vertebra
3) Android - the inlet is heart-shaped and the cavity is funnel-shaped with a contracted outlet
4) Platypolloid - a wide pelvis flattened at the brim with the sacral promontory pushed forward
Name the 5 main bones of the fetal cranium
2 parietal
2 frontal
1 occipital
Give the name of the suture separating the frontal bones from the parietal?
Coronal suture
Give the name of the suture separating the two parietal bones
Sagittal suture
Give the name of the suture separating the occipital bone from the parietal bones
Lamboid suture
Give the name of the suture separating the frontal bones
Frontal suture
What is a fontanella?
The irregular membranous area at the meeting of two sutures
Name the membranous area at the junction of the coronal and Sagittal suture
Frontal suture
When does the bregma ossify?
18months post natal
Name the fontanella at the junction of the sagittal and lamboid suture
Posterior fontanella or lambda
Cause of caput seccedaneum
During labour the dilating cervix May press on the fetal scalp preventing venous blood and lymphatic fluid from flowing normally. This may result in a boggy tissue swelling
It usually disappears within 24hours of birth
Describe the degrees of moulding
Moulding can be assessed vaginally
1+ suture lines meet
2 + bones overlap but can be reduced with gentle pressure
3+ bones overlap and are irreducible with gentle pressure
Term given to the lowermost part of the fetus presenting to the pelvis.
Presentation
- in 95% it is the vertex = normal
- anything other than vertex is malpresentation
Term given to the most definable peripheral land mark of the presenting part
Denominator
Occiput for vertex
Mentum for face
Sacrum for breech
Define station
The relationship of the most prominent leading part of the presenting part to the ischial spines expressed as +/- 1,2,3cm
When does the zygote enter the uterus?
Day 3-5
When does implantation of the blastocyst occur?
Day 7 and is finished by day 11
What does the inner call mass of the blastocyst form?
The embryo, yolk sac and amniotic cavity
What does the trophoblast form?
The future placenta, chorion and extraembryonic mesoderm
When the blastocyst embeds in the decidua, trophoblastic cells differentiate and the embryo becomes surrounded by two layers:
The inner mononuclear cytotrophoblast
And
The outer mulitnucleated syncytiotrophoblasts
In early placenta development__________ Invade endometrial blood vessels forming interotrophoblastic maternal blood filled sinuses_______.
In early placenta development trophoblasts Invade endometrial blood vessels forming interotrophoblastic maternal blood filled sinuses, lacunar spaces
In early placenta development,_______ cells advance as early or primitive vili, consisting of cytotrophoblasts surrounded by the syncytium
In early placenta development, trophoblastic cells advance as early or primitive vili, consisting of cytotrophoblasts surrounded by the syncytium
When are fetal blood vessels completed by?
Day 21…
Early vili mature into secondary and tertiary vili and the mesodermal core develops to form blood vessels by day 21
How many stem vili are there in the placenta?
60, each cotyledon contains 3-4 major stem vili
Describe the placenta at term
20cm & 500g
Fetal surface is smooth covered by amnion
Maternal surface is spongy and rough divided by cotyledons supplied by its own spiral artery
Name the vessels in the umbilical cord
2 umbilical arteries (carrying deoxygenated blood from the fetus to placenta)
1 umbilical vein (carrying oxygenated blood from the placenta to the fetus)
Blood flow 350ml/min
The cord is 30-90cm
Name the systems in the placental circulation
1) Uteroplacental (maternal blood circulating through the intervillous space at 500ml/min)
2) fetoplacental
How do spiral arteries adapt to the increasing demand to the placental bed
Spiral arteries become low pressure, high flow vessels
- they become tortuous, dilated and less elastic by trophoblasic invasion
Describe trophoblastic invasion of spiral arteries
trophoblasts invade to enhance blood supply to the placental bed
1) 1st trimester the decidual segments of the spiral arterioles are modified
2) second trimester invasion results in myometrial segment modification