obstetrics Flashcards
formula for calculating EDD
FIRST day of LMP minus 3 months plus 7 days if 28 day cycle. Add or subtract a day for each day longer/shorter the cycle is. Some obstetricians prefer to add 10 days
What proportion of women give birth within 5 and 10 days of their EDD?
40 within 5, 2/3 within 10
what is the average number of days from LMP to due date?
283 days
symptoms of pregnancy
nausea/vomitting, commonly within 2 weeks of missing period, frequency of micturation
what are the basic principles of CVS and amniocentesis?
amniocentesis; 15-17 weeks, 0.5-1% misscarraige, 2-5% won’t work, chromosome number by 3 days, karyotype 2-3 weeks, fine needle transabdo
CVS, slightly more risky 2% misscarriage, 10-12 weeks, not before as more risk, chromosome number by 3 days, karyotype 2-3 weeks, fine needle transabdo or transcervical
May detect other abnormalities eg CF, sickle cell, rhesus (will be given anti d injection),
Other risks, damage to placenta (usually repairs itself, fetal deformities in CVS (loss of digits, much lower after 10 weeks), club foot in amniocentesis (very low after 15 weeks), infection (about 1 in 1000). Very occasional detection of mosaicism in CVS meaning some placental cells affected some not, may require amniocentesis. CVS cannot detect neural tube defects, amnio and a blood test can
What routine screening is done on a first antenatal check
height, weight, BMI (less than 20 increased risk of fetal growth restriction and perinatal mortality, poor weight gain assoc with IUGR), bp, urine dip (proteinuria, haematuria, gycosuria)
Haematological for anaemia, blood group, rubella, syphilis
If risk factors, B-haemoglobinopathies, hep b, HIV
when is anaemia screened for during pregnancy,
first visit, 28 weeks and 36 weeks
what type of anaemia is more common during pregnancy, which others can occur?
Fe deficiency in 90% of cases, can be macrocytic due to folate deficiency/various parasitic infections
at what stage and in what incidences should patients be screened for diabetes?
28 week, 1st degree relative with diabetes, prev unexplained stillbirth, previous infant born >4kg, BMI >35, repeated glycosuria
What previous medical conditions need to be noted in an obstetric history?
Diabetes, cardiac disease, hypertension, renal, infectious disease (HIV/hepititis)
In diabetes screening, fasting blood glucose levels of less than ….mmol/l indicates no need to test further than this. If it is higher than this a gtt should be performed
4.5
What effects does smoking have on perinatal mortality/morbidity?
Reduces birthweight and crown heel length. Perinatal mortality increased 20% if smoking 20 a day and 35% in excess of this
What is the definition of pregnancy induced hypertension
Systolic at least 140 or diastolic at least 90 on 2 or more occasions after 20 weeks and before 24 hours postpartum. Can also be rise of at least 30 systolic/15 diastolic
What is the definition of protein urea
Concentrations greater than 0.3g/l in 24 hour collection or greater than 1g/l on random sample 2 occasions 6 hours apart
What is the definition of odema
Pitting odema or weight gain >2.3kg in a week
What is defined as mild/severepre-eclampsia
Diastolic 110 severe
What are the symptoms of pre-eclampsia/impending eclampsia? Which is most significant?
Frontal headache, blurred vision. Hyperactive reflexes, abdo pain (epigastric), abdo pain most significant
How would mild pre-eclampsia be managed?
Hospital. Rest and observation, plasma urate, plt count, 24 hr urine, creatinine clearance, assess fetal growth and placenta
Improves, manage as opt, persistent, anti hypertensive, deliver at 36 with epidural
How would severe preeclampsia be managed?
Anti-convulsants (mgSO4, diazepam), control bp hydralazine
Monitor bp, resp, CVP, colour, pulse, PCWP, strict fluid balance, delivery of infant
What are the complications of pre eclampsia?
Placental abruption, reduced glomerular filtration (oliguria and anuria), intrahepatic haemorrhage and liver failure, dic and consequences, maternal complications eg; cerebral infarction, heart failure, ards
Risk factors for developing pre eclampsia
History of preeclampsia. A personal or family history of preeclampsia increases your risk of developing the condition.
First pregnancy. The risk of developing preeclampsia is highest during your first pregnancy.
New paternity. Each pregnancy with a new partner increases the risk of preeclampsia over a second or third pregnancy with the same partner.
Age. The risk of preeclampsia is higher for pregnant women younger than 20 and older than 40.
Obesity. The risk of preeclampsia is higher if you’re obese.
Multiple pregnancy. Preeclampsia is more common in women who are carrying twins, triplets or other multiples.
Prolonged interval between pregnancies. This seems to increase the risk of preeclampsia.
Diabetes and gestational diabetes. Women who develop gestational diabetes have a higher risk of developing preeclampsia as the pregnancy progresses.
History of certain conditions. Having certain conditions before you become pregnant — such as chronic high blood pressure, migraine headaches, diabetes, kidney disease, rheumatoid arthritis or lupus — increases the risk of preeclampsia.
Which blood tests should be performed in pre eclampsia/hypertension and why?
FBC, especially platelets, renal and lfts, uric acid (good indicator of progression), clotting studies if severe, catecholamine (specially if severe and no protein, phaeochromocytoma)
What fetoplacental investigations should be performed in pre eclampsia?
Fetal ultrasound. Your doctor may also recommend close monitoring of your baby’s growth, typically through ultrasound twice a week This test directs high-frequency sound waves at the tissues in your abdominal area. These sound waves bounce off the curves and variations in your body, including your baby. The sound waves are translated into a pattern of light and dark areas — creating images of your baby on a monitor that can be recorded electronically or on film for a look at the inside of your uterus.
Nonstress test or biophysical profile. These make sure your baby is getting enough oxygen and nourishment. A nonstress test is a simple procedure that checks how your baby’s heart rate reacts when your baby moves. Your baby is doing fine if the heart rate increases at least 15 beats a minute for at least 15 seconds twice in a 20-minute period. A biophysical profile combines an ultrasound with a nonstress test to provide more information about your baby’s breathing, tone, movement and the volume of amniotic fluid in your uterus.
Doppler flow studies of umbilicus. Increase in systole to diastole flow ratio or reversal of flow indicate increased vascular resistance and fetal compromise,
Antenatal ctg
What would be the procedure for induction of a woman with preeclampsia?
Ripen cervix if not ripe with prostaglandin e2 in post fornix (Caesarian if unripe and persistent proteinuria/fits)
ARM
Oxytocin infusion if no labour within an hour of ARM. Infusions starting at 1-4mu/min increasing to 32 every half hour until response
Discontinue if evidence of fetal distress or excessively strong/frequent contractions
What drugs are used to treat acute hypertension in pregnancy
Hydralazine bolus 5mg, labetalol 20 mg
What percentage of pregnancies are affected by hypertension/pre eclampsia/eclampsia
In the uk, hypertension affects 10-15%, but only 2-3% will also develop proteinuria, les than 1 in 100 develop eclampsia
under which circumstances should delivery of infant occur in a patient with pre eclampsia
Nonreassuring fetal heart status
Ruptured membrane
Uncontrollable BP
Oligohydramnios, with amniotic fluid index (AFI) of less than 5 cm
Severe intrauterine growth restriction in which the estimated fetal weight is less than 5%
Oliguria (< 500 mL/24 hr)
Serum creatinine level of at least 1.5 mg/dL
Pulmonary edema
Shortness of breath or chest pain with pulse oximetry of < 94% on room air
Headache that is persistent and severe
Right upper quadrant tenderness
Development of HELLP syndrome
what should the management of eclampsia after delivery be?
continues for up to 7 days, fits can occur up to 4 weeks after delivery but majority occur before 48 hours. After this epilepsy or cortical vein thrombosis must be considered.
Management; maintain in quiet environment under constant observation, maintain appropriate sedation levels. MgSO4 if used continue to 24 hours after last fit, continue antihypertensives until bp normal. Hypertension may persist for 6 weeks
What proportion of eclamptic fits occur after delivery/after 48 hours
45% after deliver, 12% after 48hr
what are the values in a GTT suggest normal/abnormal glucose tolerance
75g loading dose of glucose, normal fasting less than 6mmol/l fasting and 2 hour less than 7.8 mmol
gestational IGT, fasting 6-7 and 2 hour 7.8-11.1
diabetes fasting >7 and 2 hour >11.1