Obstetrics Flashcards
On which day of the menstrual cycle does ovulation take place?
Day 14
Caused by release of luteinising hormone.
Where does fertilisation occur?
Fallopian tube
The blastocyst implants into the __1__ in the fundus of the uterus on day __2__.
1) decidua
2) 23
After the blastocyst has implanted there is
production of __1__ which causes the ovary to produce progesterone from the __2__ until 10-12 weeks, where the __3__ takes over.
1) B-hCG
2) corpus luteum
3) placenta
What value denotes a positive pregnancy test?
hCG >25 IU/mL
B-hCG stimulates release of __?__, which is the main pregnancy hormone that modifies maternal physiology.
Progesterone
What are some of the less desirable effects of progesterone on maternal physiology?
Stress incontinence, acid reflux and constipation due to progesterone induced smooth muscle relaxations
What infections are commonly associated with poor foetal growth?
Viral: Rubella, CMV, VZ, measles, hepatitis A & B
Protozoan: Toxoplasma
Bacterial: Listeria, syphilis
How is the estimated date of delivery calculated?
Date of last menstrual period + 9 months + 7 days
A pregnant lady attends for her booking appointment. Her last menstrual period was on 21/08/2020, what is her estimated due date?
28/05/2021
LMP + 7 days + 9 months
What bloods are done at the maternity booking visit?
First antenatal bloods:
- FBC: anaemia
- Group and save
- Haemoglobinopathies
- Blood group and antibody screen; early identification of rhesus-negative women
- Infection screen: HIV, Hepatitis B, Syphilis, Rubella
How is gravida and parity counted?
Parity: number of births after 24 weeks (inc. stillborn).
Losses before 24 weeks are given after the +.
e.g. Parity 1 + 0 indicates this woman has had one previous birth after 24 weeks, and no miscarriage or termination prior to 24 weeks.
Gravida also includes the current pregnancy, if applicable.
So a pregnant woman with two previous kids and an early miscarriage is:
G4 P2 + 1
What are the recommended folic acid doses for pregnant women?
400 micrograms/day for most women.
5 mg/day for higher risk women (previous neural tube defect or women with epilepsy).
How frequent are nulliparous women ideally seen for antenatal appointments?
10 antenatal appointments for nulliparous:
Booking (~10wks), 16, 25, 28, 31, 34, 36, 38, 40 and 41 weeks.
All the same as multiparous except two extras at 25 and 31 weeks.
How frequent are multiparous women ideally seen for antenatal appointments?
8 antenatal appointments for multiparous:
Booking (~10wks), 16, 28, 34, 36, 38, 40 and 41 weeks.
This feature is measured at the 11+2 - 14+2 week scan and may help identify foetuses at high risk of having Down’s syndrome.
Nuchal transparency.
An enlarged nuchal transparency is >0.35cm.
What measurements are taken at the 11 week scan that contribute to calculating the risk of a foetus having Down’s syndrome?
- Nuchal transparency (enlarged if >0.35cm)
- hCG
- PAPPA (pregnancy-associated plasma protein A, low levels may be seen in Down’s syndrome)
Management of backache and sciatica in pregnancy
Lifestyle mods, e.g. sleeping positions
Alternative therapies, e.g. massage
Physiotherapy
Simple analgesia
Management of haemorrhoids in pregnancy
Avoid constipation from early pregnancy
Ice packs and digital reduction of prolapsed haemorrhoids
Suppository and ointment for symptomatic relief
Surgical referral, if thrombosed
Management of varicose veins in pregnancy
Regular exercise
Compression hosiery
Consider thromboprophylaxis if other risk factors are present
Management of carpal tunnel syndrome in pregnancy
sleeping with hands over side of bed may help
Wrist splints may benefit
Usually resolves spontaneously after delivery
If evidence of neurology deficit, surgical referral may be indicated
Management of symphysis pubis dysfunction in pregnancy
Physiotherapy
Simple analgesia
Limit abduction of legs at delivery
C-section not indicated
Management of constipation in pregnancy
Usually improves through course of pregnancy
Lifestyle mods, e.g. increased fibre and water intake
Osmotic laxatives (lactulose)
Management of GORD in pregnancy
Lifestyle mods, e.g. sleeping propped up, avoid spicy food
Alginate preparations and simple antacids
If severe, H2 receptor antagonists (ranitidine)
How common is nausea and vomiting in pregnancy?
Nausea: 80-85%
Vomiting: 52%
True or false: Normal nausea and vomiting associated with pregnancy often resolves within the 16-20 weeks.
True
What is the most common complaint in pregnancy?
Nausea and vomiting
Management of nausea and vomiting in pregnancy?
Lifestyle modifications, e.g. smaller meals, increase fluid intake
Ginger, e.g. tea
Acupressure
Antiemetics
Hyperemesis gravidarum may warrant hospital admission
What sequelae are associated with hyperemesis gravidarum?
Maternal:
- Hyponatraemia (rapid reversal may result in central pontine myelinosis)
- Thiamine deficiency → Wernicke’s encephalopathy
Fetal:
- intrauterine growth restriction (IUGR) if mother loses 10% of her body weight
- Fetal death may occur in cases of Wernicke’s encephalopathy
What fluid is contraindicated in patients with hyperemesis gravidarum?
Dextrose-containing fluid must not be given to women with hyperemesis gravidarum as they can precipitate Wernicke’s encephalopathy
Which antiemetics are recommended for hyperemesis gravidarum?
Metoclopramide 10 mg/8 hr PO/IM/IV
Cyclizine 50 mg/8 hr
Prochlorperazine 12.5 mg tds IV/IM or 5 mg PO tds
What is given in hyperemesis gravidarum to protect mother from developing Wernicke’s encephalopathy?
Thiamine
Thiamine hydrochloride 25-50 mg PO tds
or
Thiamine 100 mg infusion weekly
When are corticosteroids indicated in the treatment of hyperemesis gravidarum?
If vomiting is protracted and unresponsive to fluids and antiemetics, consider a trial of corticosteroids (prednisolone 40-50 mg PO daily in divided doses or hydrocortisone 100 mg/12 h IV).
What measure is used to calculation gestation between 8 and 13 weeks?
Crown-rump length (CRL)
Measured by USS from one fetal crown to the other along its longitudinal axis in a straight line.
What measurements can be used to measure growth of the foetus?
Crown-rump length
External uterine measurements
Biparietal diameter
Head circumference
Abdominal circumference
Femur length
What physiological factors are used to customise fetal growth charts?
Maternal height (although relevant, paternal height is not used)
Maternal weight in early pregnancy
Parity
Ethnic origin
Gender of fetus
What are some reasons for a uterus measuring small for dates?
Wrong dates
Oligohydramnios
Intrauterine growth restriction (IUGR)
Presenting part deep in pelvis
Abnormal fetal lie
What are some reasons for a uterus measuring large for dates?
Wrong dates
Polyhydramnios
Macrosomia
Multiple pregnancy
Presence of fibroids
What causes polyhydramnios?
Idiopathic
Maternal disorders (diabetes, renal failure)
Twins (twin-twin transfusion syndrome)
Fetal anomaly (upper GI obst., inability to swallow, chest abnormality, myotonic dystrophy)
What are the clinical features of polyhydramnios?
Maternal discomfort
Large for dates
Taut uterus
Fetal parts difficult to palpate
What are the complications associated with polyhydramnios?
Preterm labour, maternal discomfort, abnormal le and malpresentation
True or false: If a pregnant woman comes in with bleeding at 5 weeks a transvaginal ultrasound is indicated to check the status of the fetus.
False.
To check the viability of the fetus you need to see the heart pulsating. The fetal heart cannot be seen to beat until after 6 weeks.
What is the earliest you can tell the gender of a fetus?
15-16 weeks
What are the risk factors associated with placenta abruption?
Hypertension (including preclampsia), smoking, trauma to maternal abdomen, cocaine, polyhydramnios, multiple pregnancy, IUGR
How might placental abruption present?
Maternal collapse, feeling cold, light-headedness, restlessness, distress/panic, painful rigid abdomen and vaginal bleeding.
__?__ is the premature separation of the placenta from the uterine wall, leading to haemorrhage that is acutely dangerous for the mother and fetus.
Placental abruption
What risk factors are associates with placenta praevia?
Multiple gestation, previous c-section, uterine structural anomaly, assisted conception
How might placenta praevia present?
Low lying placenta at 20 week scan, maternal collapse, feeling cold, light-headedness, restlessness, distress, painless vaginal bleeding.
True or false: placental abruption is characteristically associated with painless bleeding.
False.
Placental abruption is associated with a painful, rigid abdomen alongside bleeding (to varying amount vaginally, as may be concealed).
Painless vaginal bleeding is characteristic of placenta praevia.
How should patients be investigated if there is a suspicion of placenta praevia?
Transvaginal USS to allow accurate measurement of the placental edge from the internal os.
True or false: Placenta praevia is generally more dangerous for the mother, while placental abruption is more dangerous for the fetus.
True.
Placenta praevia is most dangerous for the mother.
Placental abruption is more dangerous for the fetus than the mother.
What is vasa praevia?
Vasa previa occurs when fetal vessels traverse the fetal membranes over the internal cervical os.
How does vasa praevia present?
The diagnosis of vasa praevia is usually suspected when rupture of the membranes (spontaneous or artificial) is accompanied by painless fresh vaginal bleeding from rupture of the fetal vessels.
Once vasa praevia is suspected, what must happen?
If the fetus is still alive, once the diagnosis of vasa praevia is suspected the immediate course of action is delivery by emergency Caesarean section.
Placenta praevia is most dangerous for the __?__.
Placenta praevia is most dangerous for the MOTHER.
Placental abruption is more dangerous for the __?__ than the __?__.
Placental abruption is more dangerous for the FETUS than the MOTHER.
Vasa praevia is not dangerous for the __?__ but is nearly always fatal for the __?__.
Vasa praevia is not dangerous for the MOTHER but is nearly always fatal for the BABY.
What are the main causes of postpartum haemorrhage?
4 T’s:
Tone: uterus fails to contract
Trauma: Injury to tissue leading to haemorrhage
Tissue: Infected tissue or tissue that is physically impeding uterine contraction
Thrombin: Thrombocytopenia, coagulopathies, DIC
If a pregnant women tests positive for gestational diabetes, how is this managed?
If fasting glucose <7, trial diet and exercise.
- If targets not met after 2 weeks, start metformin
- If targets still not met, add insulin (short-acting for gest diabetes).
If fasting glucose >=7, start insulin.
Glibenclamide may be offered, but only for women who cannot tolerate metformin or those who fail to meet targets with metformin but decline insulin.
What is first-line for management of eclampsia?
Magnesium sulphate
In eclampsia, seizures are both prevented and treated with magnesium sulphate. If magnesium sulphate is not available, or if it fails to terminate the seizure, a benzodiazepine (such as midazolam) can be considered.
Due to the elevated blood pressure, an anti-hypertensive agent should also be given (labetalol, hydralazine, nifedipine are good options)
What are the diagnostic criteria for hyperemesis gravidarum?
Hyperemesis gravidarum, diagnostic triad:
- 5% pre-pregnancy weight loss
- Dehydration
- Electrolyte imbalance
What drug should be administered as part of active management of the third stage of labour? When is it given?
10 IU of IM oxytocin should be administered after delivery of the anterior shoulder.
What are the two main contraindications for VBAC?
Previous uterine rupture
Classical caesarean scar
