On this episode of the podcast, Penny looks at a recent study published in the NEJM looking at the genetic basis for certain congenital defects and the possible role of niacin (vitamin B3) in their prevention. In particular, how does this paper stack up to the claims in the media, and what does it mean for clinicians?
In other news, there is a new Australian O&G podcast on the block. Check out Conversations in Obstetrics and Gynaecology here.
And, you can catch up with Penny at the RANZCOG ASM in Auckland in October 2017 where she will be presenting a masterclass in Social Media. Come along!
In this episode of the podcast, Penny has a rant about one of her pet peeves – the ever changing due date – and gives lots of tips on how to determine the estimated due date (EDD) with the greatest accuracy.
Take home messages:
The only way to know the exact EDD for certain is an IVF pregnancy with a known implantation date.
The next most accurate method is an ultrasound measurement of crown-rump length between ~7 and 13+6 weeks (or maybe even up to 23 weeks, if you believe the Canadians). Dates based on LMP are fraught with assumptions and risks of error.
Transabdominal measurements are just as good as transvaginal scans at determining the EDD.
The margin of error increases the later the scan is done – about 5 days in first trimester, 7-10 days up to 20 weeks, 2 weeks in late second trimester, and up to 3 weeks in third trimester.
International organisations agree that ultrasound should be offered universally between 8 and 13+6 weeks and an EDD based on first trimester crown-rump length should be the definitive date. Note, however, that in practice, some radiologists will leave the EDD as per the LMP if it’s within 5-7 days.
Offering universal early dating scan reduces the rate of interventions in the post-dates period.
Check for inaccurate dates written on request forms, or typos on reports.
Never use HCG to determine gestational age.
Don’t be fooled into adjusting the due dates based on growth parameters later in pregnancy!
Australasian Society of Ultrasound Medicine recommendations:
Earliest measurement of gestational age in pregnancy should be the definitive assessment
If the first scan is after the first trimester –> if the ultrasound measurements are within one week of EDD as determined by LMP date, the scan confirms the LMP date.
If the first scan is 14 – 20 weeks and differs from the LMP date by more than one week, a new EDD is assigned, if the different measurement parameters are in agreement.
This week we discuss bleeding and pain in early pregnancy, and how to diagnose miscarriage.
Take Home Messages:
Miscarriage occurs in 1 in 5-6 confirmed pregnancies.
A pregnancy that has not yet been sighted on USS remains a ‘Pregnancy of Unknown Location’ and remains a possible ectopic pregnancy until proven otherwise.
Serial B-hCGs can be helpful in guiding your clinical decision making, however you cannot ‘locate’ a pregnancy with a blood test alone.
In the symptomatic patient, a falling, plateauing or rising B-hCG can ALL be associated with an ectopic pregnancy – these must be followed until an ectopic pregnancy can be diagnosed or excluded.
A rise of B-hCG in 48hrs of > 63% is relatively reassuring for an ongoing intrauterine pregnancy, make sure to confirm it with an USS as soon as you can.
The ultrasound diagnosis of both a blighted ovum and a missed miscarriage (with a foetal pole) have strict criteria – refer ASUM guidelines below.
This week on the podcast we examine the common and very troublesome problem of vomiting in pregnancy, from mild morning sickness to the more severe hyperemesis gravidarum.
Take home messages:
Standard investigations include FBC, UEC, LFT, TFTs, urinalysis and obstetric ultrasound
In severe cases, consider secondary causes of vomiting such as urosepsis, GI or neurological pathology
Dietary advice, ginger and P6 acupressure have mixed evidence but are unlikely to do harm and useful for some patients
Pyridoxine (vitamin B6) and doxylamine have the best evidence for safety and efficacy and are recommended for first line
Second line options include metoclopramide, prochlorperazine and promethazine which are all considered safe in early pregnancy
If significant ketonuria, electrolyte imbalance or dehydration, refer for intravenous hydration, parenteral anti-emetics and thiamine
Bits & Bumps 