Case 14- Childbirth Flashcards
How the female pelvis assists in childbirth
The fetus rotates to align with the widest section of the female pelvis. The pelvic floor acts like a funnel to guide the fetal head through the birth canal. The rotation of the fetal head is due to the resistance from the pelvic floor.
Most common presentation in childbirth
Longitudinal cephalic line
Cardinal movements of childbirth
1) Engagement
2) Descent
3) Flexion
4) Internal rotation
5) Crowning
6) Extension
7) External rotation and restitution
Fetal position prior to descent
The body is facing head down towards. The back is curved and flexed, with their knees drawn into their chest.
Cardinal movement- Engagement
Largest diameter of the fetus head fits into the largest diameter of the maternal pelvis. Then moves towards the pelvis brim in either the left or right occipto-transverse position.
Cardinal movements- Descent
The baby descends through the pelvic inlet towards the pelvic floor. Occurs due to uterine contraction, amniotic fluid pressure and abdominal muscle contractions.
Cardinal movements- Flexion
The fetal head meets the pelvic floor and cervical flexion occurs. Allows foetus to be sub-occipito bregmatic. In this position the fetal skull has the smallest diameter
Cardinal movements- Internal rotation
The pelvic floor has a gutter shape (forward and downward slope), causes the head to rotate from a left or right occipto-transverse position to an occipto-anterior position.
Cardinal movement- Crowning
The largest diameter of the fetal head goes through the narrowest part of the bony pelvis. The head is visible at the vulva and no longer retreats between contractions.
Cardinal movements- Extension
The occiput slips beneath the suprapubic arch as the head extends, the nape of the neck pivots against the arch. Extension of the head causes stretching of the perineum.
Cardinal movements- External rotation and restitution
The head externally rotates to face the right or left medial thigh of the mother. The shoulders rotate from a transverse position to an anterior-posterior position. The re-alignment of the shoulders with the head is restitution.
Partuition
Delivery
Delivery of a baby
- Uterine contractions causes flexure of the uterine neck, this means the smallest diameter of the fetal skull is presented.
- The fetus moves further down the pelvis and the Occiput meets the pelvic floor, there is rotation of the fetal skull.
- The shoulders do not rotate and are misaligned to the skull.
- Causes the Occiput to present (crowning).
- The fetal face is birthed and the shoulders realign in a process called restitution. The anterior shoulder moves below the subpubic arch and is delivered first
- The midwife will do lateral flexion to release the posterior shoulder
- Following normal labour the placenta is birthed.
How is the sacrum adapted for childbirth
It is curved (curve of carus)
Foetal skull
Near the end of pregnancy the cartilaginous neurocranium ossifies to form the adult skull. At the calvaria (skull cap), flat bones are separated by dense connective tissue membranes that eventually form sutures (fibrous joints). Large fibrous areas called fontanelles are located between certain sutures (anterior, posterior, sphenoid, and mastoid). They are because the bones have not completely fused, they allow the bones to slide over each other (molding), aids in partition.
Symmetry in the foetal skull
All the bones are paired and you have one on each side i.e. a left and right frontal bone
Foetal skull- sutures
- The frontal suture is between the two frontal bones fuse after 2-3 months
- The coronal suture is between the frontal and parietal bone.
- The sagittal suture is between the two parietal bones
- The lanmboid suture is between the Occiput and parietal bone
Role of fontanelles in the fetal skull
Allow the skull bones to move over each other during birth, to aid passage of the fetal skull through the narrow pelvis. It allows for rapid stretching as the brain grows
Divisions of the fetal skull
Down from the Glabella is the face. The underside of the skull is the base of the skull. The remained of the skull is classified as the vault. The Clavaria is the top part of the skull. Compared to an adult skull the face is a lot smaller then the vault
What bones are in the Clavaria
Frontal, Parietal, Temporal and Occipital
The Fontanelles in the fetal clavaria
- Anterior fontanelle- bounded by the coronal, frontal and sagittal suture. Fuses after 18 months
- Posterior fontanelle- bounded by the sagittal and lambdoid suture, it fuses after 3 months
- Sphenoidal fontanelle- fuses after 6 months, lateral side
- Mastoid fontanelle- lateral backside, fuses between 6-18 months.
Cleidocranial dysplasia (CCD)
Anterior fontanelles dont fuse, causes lack of clavicles, supernumerary teeth
Signs and symptoms of prgnancy
- Amenorrhoea (secondary)- stopping your period
- Nausea- with or without vomiting, 4-7th week
- Breast enlargement and tenderness
How is a pregnancy confirmed
1) Home pregnancy tests
2) GP confirms by sending off a urine sample
What do pregnancy tests check for
hCG (Human chorionic gonadotropin). On the test hCG binds to the antibodies in the test zone, they are associated with an enzyme that changes colour. Excess antibodies bind to the mobilised antibodies in the control zone to show the test has worked correctly.
What do pregnancy tests check for
hCG (Human chorionic gonadotropin). On the test hCG binds to the antibodies in the test zone, they are associated with an enzyme that changes colour. Excess antibodies bind to the mobilised antibodies in the control zone to show the test has worked correctly.
Hcg
We measure or it in pregnancy as its the first hormones produced by the Synctio-trophoblasts and rises by a lot. It maintains the corpus luteum and peaks around week 10. It replaces LH in promoting Progesterone production
Placental steroidogenesis
At 8 weeks there is a shift in Steroidogenesis from the ovary to the placenta, requiring cooperation between the maternal and foetal systems
Connections in hormone production between the mother, placenta and fetus
1) Cholesterol is produced from maternal blood.
2) The Progesterone is produced in the Placenta as the fetus lacks 3β-HSD and is transported to maternal and fetal blood.
3) The fetus converts Cholesterol and Progesterone into DHEA, this is then converted to oestrogen in the placenta by Aromatase. The Placenta can not produce its own DHEA
Progesterone
Inhibits FSH and LH. Increases breast development especially alveolar and lobular development. It relaxes smooth muscle, in the uterus it inhibits oxytocin receptors. Maintains endometrial lining.
Oestrogen
Inhibits FSH and LH. Stimulates breast growth especially ductal tissue. Stimulates uterine growth (smooth muscle hypertrophy). Relaxes joints and ligaments to allow accommodation for the fetus. Softens cervix.
Human placental lactogen
Decreases insulin sensitivity, increases maternal blood glucose but mother uses less of it. Increases lipolysis so more fatty acids are released. The mother uses more of the fatty acids so the fetus has more access to glucose. Has an important role in metabolism, supporting fetal nutrition even in mild maternal malnutrition.
Relaxin-hormone
It relaxes maternal structures before delivery through 3 actions: causing rupture of the fetal membrane, allowing softening and dilation of the cervix and allowing the pelvic ligaments to stretch
Role of Oxytocin and Prolactin
Oxytocin- causes contraction of the uterus
Prolactin- stimulates lactation
Weight gain in pregnancy
The mother gains 0.3-0.5kg per week. Total weight gain is 12.5kg. Contributions to weight gain are breast tissue, baby, placenta, uterus, amniotic fluid, fat stores and blood supply.
Changes to the reproductive tract during pregnancy
The volume and weight of the uterus increases from 50g to 1kg. There is hypertrophy till week 20 then it stretches, blood supply increases by ten times. The cervix increases in glands and there secretions. The cervical canal fills with a thick mucus plug. The vagina and canal becomes more elastic to permit dilation, there is an increase in bacteria which lowers the pH in the vagina.
Changes to the Breast during pregnancy
There is tenderness, increased size, vascularity, nipple enlargement, pigmentation and enlargement of areolas. Oestrogen, growth hormones and Glucocorticoid’s cause duct proliferation. Progesterone and Prolactin cause Alveolar/lobules (milk secreting tissue) proliferation.
Haematological changes during pregnancy
Increase in blood volume (30%), increased plasma volume, RBC and clotting fibres / fibrinogen. Decreased Albumin, this can cause Oedema (albumin increase) and DVT (clotting factor increase). Plasma volume increases a lot more then RBC causing Haemodilution
How decreased albumin causes oedema
- H2O: Is disassociated into H+ & O2
- H+ attracted to Albumin- (causes high oncotic pressure)
- H2O moves into the circulation
- Decreased protein in the circulation (Albumin)
- H2O stays in interstitium as the oncotic pressure is lower
- Causes peripheral oedema
Adaptions to mother Lymphocytes
The fetus is an allograph as it expresses paternal antigens and should be rejected by the mother. The mothers lymphocyte count is maintained but function and cell mediated immunity decreases. This helps to prevent rejection of the fetus but lowers maternal resistance to infection. Maternal immunity is transferred to the fetus as the antibodies can cross the placenta.
Cardiac adaptions in pregnancy
Hypertrophy (approx. 10%). Increased cardiac output through increased heart rate and stroke volume, stroke volume increases more. There is increased blood flow to the uterus. Causes a displaced apex beat and a systolic flow murmer. Peripheral resistance is decreases via vasodilation. Progesterone relaxes smooth muscle and influences heart rate. There is a decrease in blood pressure in the first trimester which returns to normal towards the third trimester. An increase in BP should be investigated as it may be related to pre-eclampsia.
Cardiac complications with pregnancy
It can put pressure on the maternal circulation, precipitating or worsening cardiac failure
IVC and supine hypotension
Occurs at 20 weeks when the uterus compresses the IVC when the patient is supine. It decreases CO by 30%. When the mother is supine you should raise the right hip and lie on the left side, using the left lateral tilt.
Compression of the IVC can cause varicose veins and swollen ankles It also causes a shift in the apex beat of the heart
What does the increase in cardiac output cause in pregnant women
A benign systolic murmur
Respiratory adaptions in pregnant women
Oxygen consumption increases by 20% due to an increased metabolic rate. Progesterone increases the sensitivity of the CNS to CO2 to stimulate respiration. There is an increase in minute volume (air flow/min) and tidal volume (by 40%). Respiratory rate remains the same.
Changes to the chest and lungs during pregnancy
There is an increase in intra-abdominal pressure due to the growing fetus, this causes the diaphragm to rise by 4cm. The thoracic cage circumference increases by 5cm. The functional residual capacity reduces due to compression. Oxygen saturation decreases during pregnancy
Renal adaptions during pregnancy
Increased renal blood flow (30-50%), increased GFR, increased urinary output and increased water retention required for increased plasma. There is mild proteinuria and glycosuria due to the increase in filtration. There is an increase in the size of the kidneys and ureters. There is relaxation of ureter smooth muscle causing urinary stasis and increased risk of UTI and pyelonephritis.
Other changes during pregnancy
Gastrointestinal- Haemorrhoids and constipation are more common
Metabolic i.e. increased insulin resistance- increased glucose in the blood
Musculoskeletal i.e. lower back pain
Dermatological i.e. skin pigmentation
New born screening
- A physical exam is offered within 72 hours of birth
- Hearing test using an automates otoacoustic emission test
- Blood spot test
- Heal prick test screens for 9 conditions (sickle cell disease, cystic fibrosis, congenital hypothyroidism, 6 different inherited metabolic diseases).
Cancer Screening
- Cervical screening- smear test for women aged 25-64
- Breast screening- x-ray (mammogram) for women aged 50-70
- Bowel cancer screening, a home test for stool is offered for people aged 60-74. In some regions an endoscopic exam is offered from 55.
Abdominal aortic eye screening
An ultrasound offered to men >65
Diabetic eye screening
Tests for early signs of diabetic retinopathy. Annual test for people with diabetes over 12
Using a pregnancy wheel to estimate date of delivery
Set the blue arrow to the first day of their last menstrual period. The wheel will show the estimated date for their first, second and third trimester and the Estimated date of delivery (EDD) at 40 weeks gestation. Inaccurate, especially if the patient has irregular menses, better to use ultrasound
Using an ultrasound to estimate date of delivery
Scan is usually done transabdominally. It should occur at 10-15 weeks gestation (normally 12). Scan shows fetal size, which determines weeks of gestation and estimated date of delivery. Shows the number of fetus’s present, adequate growth of the fetus, location of the fetus and confirms the precense of a heartbeat. It checks for features of ectopic or molar pregnancies and gives information on major fetal abnormalities.
Other ways to check gestational age
Measurement of crown-rump shows gestational age if done before 13 weeks. Can also be done by measuring biparietal diameter, head circumference or femur length.
Screening for downs syndrome
Done at 10-14 weeks of pregnancy uses a combined test of blood tests and ultrasound scan which measures the fluid at the back of the baby’s neck (nuchal translucency). The US for downs can occur at the dating scan but must be between 10-14 weeks after that only blood tests can be used
Screening for downs syndrome
Done at 10-14 weeks of pregnancy uses a combined test of blood tests and ultrasound scan which measures the fluid at the back of the baby’s neck (nuchal translucency). The US for downs can occur at the dating scan but must be between 10-14 weeks after that only blood tests can be used
