Progesterone for short cervix
Progesterone therapy should be considered for women with a singleton pregnancy who have a history of previous spontaneous preterm singleton birth, and is recommended for those where cervical shortening has been detected.
Progesterone therapy should be considered in asymptomatic women with an incidentally diagnosed short cervix (<20 mm) on transvaginal cervical length assessment in the midtrimester.
So, this patient should be considered on the basis of the past history of premature birth alone, regardless of cervical length.
It is important for your local ultrasound services to look at the statement as regards to standardisation of cervical length scanning technique.
When to start? 16-24 weeks and continue to 34 to 37 weeks. In the setting of a GP unit, 36 weeks would seem to be reasonable
What dose? Vaginal pessary 100mg per day
What about the cerclage?
The history of a 12 week miscarriage might be relevant to cervical damage if was a cold D&C at that gestation, especially if no misoprostol was given pre-operatively. This has much less significance if it was at 12 weeks but the sac size was smaller and she had misoprostol, or it was an incomplete miscarriage when the cervix would already be open.
I think it wise that women with history of preterm birth do have a formal visit to a specialist early in the pregnancy for management planning. This gives a chance to look at the details of first pregnancy loss and treatment. Consider the details of premature birth – was it painless dilatation? APH? Previous LLETZ? Review swabs, examination, smoking, weight. A specialist visit allows a second opinion on these issues, and also will encourage some continuity and ownership of the issue if future opinion or management is needed. Most will not deliver early so will be suitable to stay under the GP care for the birth.
Remember basic stuff like excluding chlamydia in those under 25 (?30s). If HVS showed BV, I think I would still treat with a PV clindamycin course, though the strength of evidence for benefit is perhaps less than we previously thought.
Note that the evidence is changing each report. We are still awaiting the PROGRESS trial which should give better information about baby outcomes (not just whether the woman gave birth early or not). So to explain a RR 0.31 for PTB <34 weeks, one could say: ‘if you use the progesterone pessaries it will decrease by 70% the chance of you having the baby earlier than 34 weeks’. But what is the chance of having the baby earlier than 34w – does that decrease it from 10 in a 100 to 3 in a 100 – from a 90% chance of not delivering early to a 97% chance, or from 50 in a 100 (50% chance, 1 in 2) to 15 in a 100 (15% chance, 1 in 6), ie from a 50% chance of not delivering early to an 87% chance. This makes a big difference in how to counsel.
Should we do serial scans of the cervix? Not sure. Probably a second one at 22-24 if the first was at 16-20 as that might influence the decision about cerclage.
Prophylactic steroids – probably not in 2014.
Fibronectin at 24 or 26 weeks? I haven’t been using it in this situation. Does a positive result change management or just make you worry more? A negative result would be reassuring for a couple of weeks.
One could argue in all this that preterm birth has such bigger implications for a rural family compared to a city-based family (even if what changes is the gestation alone not the actual long term baby outcome) that our threshold for treatment could be justifiably lower. So where RANZCOG says ‘consider’, we might think that ‘rural location’ is a strong consideration.