I went to a periontologist for a nuchal screen at 13 weeks. He recommended an ultrasound every 2 weeks starting at 18 weeks. My ob recommeded evert 3-4 weeks after ~28 weeks. I am currently 15 weeks, healthy and both twins are measuring right on with no problems. I have to drive 3 hrs for an ultrasound and rather limit them anyway but want to do what is best. What did your ob prescribe? Thank you in advance
Frequency of Ultrasounds for mono/di twins after 18 weeks?
That's too many for me. I had them about every 4 weeks and I was making my OB nervous. But they were measuring very close in size and they both moving well (I could tell them apart by about 25 weeks, I think). I did start having NST's at 32 weeks. I think I started them every 2 weeks, then weekly. The boys were born at 38 weeks.
Do some research about TTS. It often starts around 18 weeks. I felt OK with less ultrasounds because my first ultrasound at 22 ish weeks showed NO signs. Not everyone feels this way. So make your OWN decision and listen to your gut a lot!!
Well mine were di/di so maybe that makes a difference? But I had U/S every 4 weeks starting at 18 weeks. We had NSTs, weekly I think, starting at 32-weeks, IIRC. And at every OB appointment they'd do a quick U/S to find a heartbeat. So I saw them a lot, but not the full anatomy scans every 2 weeks. That seems like a lot, but I know TTS can sneak up on you.
My girls are MZ but were di-di. My peri had us come in for an u/s every 4 weeks, which with scheduling sometimes became 5-6 weeks, for a total of 5 u/s between 19 and 37 weeks. According to him, that was as few as possible, because things were going well. Mono-di twins do carry added risks, TTTS being the most well known. So I might have agreed to more frequent u/s.
Guess it depends on your attitude. I don't know enough about TTTS surgery to know whether it would be something I'd be willing to try if necessary. Would you induce if the OBs thought there'd be a benefit? If there's anything the u/s would change - more monitoring might be worth it. If not, don't do it.
The suggestion of every 2 weeks for mono-di twins sounds pretty standard to me. Being seen less frequently might be a reasonable choice too; it's something worth weighing.
Our MFMs/perinates seem to recommend every 2-3 weeks for mono/di to watch for TTTS from roughly 16-24ish weeks, then monthly growth sonos. It IS a lot, especially if you are having to drive that far. Best of luck working out a monitoring schedule that feels good/safe for both you and your care providers!
TTTS is a real risk with mono-di twins and it can happen quite quickly. I would absolutely err on the side of caution and go for the number of ultrasounds your peri/MFM recommends, even if it's 3 hours away (I know that's a hassle, I just think it's worth it).
I have mono-di twins who are now 7.5 months, or 5 months adjusted. I went with my high-risk OB's recommendation for ultrasounds every two weeks after 16w (I was with a high-risk OB because initially they thought my twins were mono-mono, and she was great, so I stuck with her even after they saw the membrane - then it turns out I was lucky I did). Anyway, my scans were fine until 22w when there was a mild size discordance, then it was gone at 24w, but at 26w it was back and much worse. They admitted me to hospital overnight, then I was an outpatient on bedrest with NSTs every second day and ultrasounds 2-3x per week to monitor my smaller baby. They were prepared to go in at any point and save him if they needed to, but the goal was to get to 32w. I ended up with PTL anyway (I think the babies' way of saying it was time to come out), and had them at 29w2d.
In the end what I had wasn't technically TTTS because I didn't meet many of the diagnostic criteria - just one baby with IUGR who wasn't getting what he needed from the placenta. Point being, issues with the placenta and growth discordance can be fairly quick and very serious with mono-di twins. I'd go for the scans every two weeks, just to be safe.
I never even had a peri - we are very rural here and all we have are a couple OB's an hour away. So I had an u/s at 21wks - when we found out there were twins, then one at 27wks - the soonest they could get me in again being very rural and only one tech for MANY MANY MANY towns. My next was at 35wks. I had a quick scan at 37 with the hand held machine on the OB ward to check for placement and my Duo were born at 38w5d.
I am very lucky that all was well and they were within ounces of each other the entire pregnancy - at birth they were only 4oz different and now, 22mths later they always remain 4-6oz different.