14w3d: Out

My belly and the word are both out. I have told my close friends, family, and my boss. I have booked childcare. Random colleagues are coming up to me to wish me congratulations. Presents are starting to appear in the mail.

Apart from the few moments of terror and fear, I am mostly starting to feel a little bit excited. Cautiously optimistic, sometimes. I am now officially in my second trimester.

Frustratingly, I am still having trouble finding a consistent heartbeat with my cheap eBay doppler. I am trying not to worry too much, as even the tech couldn't get a good abdominal scan at my last ultrasound with her fancy-pants machine. I have my next check-up in 11 days.

Finally, I will not be able to make it to my next IVF support group dinner. I have not yet told any of the ladies my news, as I do not see any of them outside these events. Should I send an email? Should it be individual or reply-all? What should it say?

The NT scan

This Tuesday last week I was anxiously counting down the hours until my NT test. I was a bundle of nerves, and had to break down the activity into tiny steps so that I could get through it (get dressed, leave house, get to hospital, walk through front doors, etc). My doppler still hasn’t arrived, so I had no idea if the foetus was even alive.

I arrived 30 minutes early and impatiently waited for my husband to arrive, as he left it to the last minute and only arrived 5 minutes early. Twenty minutes after that, they called us in. My first transabdominal ultrasound, I didn’t even have to take off my pants.

The technician pressed down on my belly and a grainy picture appeared. At first glance, it didn’t look that different from the scan three weeks ago, and my heart froze. But she pointed out the heartbeat and I started to relax. I thought that I had been a responsible patient by drinking a litre of water an hour beforehand, but the technician said that all I was doing was forcing my uterus further towards my spine. She sent me to the bathroom to empty my bladder, and then got down to business.

Everything looked great. The foetus was measuring 6.5 cm (12w6d) at 12w0d with a femur length of 0.68 cm and a NT thickness of 1.49mm (photo of the fetus with a hand on its nose here). I was so relieved when I saw that NT measurement. Then the technician went on to check all the organs, pointing them out as she went along: brain, stomach, kidneys, spine, fingers, feet, even the four chambers of the heart. Due to the position of my uterus, she switched to a transvaginal probe for some of the measurements, so I got a visit from my old friend too. All in all, she concluded “it is a good baby”.

The foetus waved its hands in front of its head, occasionally wiggling and kicking. Although the print outs were a bit poor, seeing the live-action movement on the screen was incredible. With my husband by my side, holding my hand and smiling at me, we could have watched that little thing for hours.

After she had finished, the supervising doctor came in to double-check the measurements. I was a little concerned that the heart rate was a little low (151 bpm) – (the mean rate is 159 +/- 3 bpm at 13 weeks). She did something where she did four different types of doppler heartbeat measurements and said that everything looked fine.

My urine, weight, and blood pressure looked good, so they printed out an official certificate of pregnancy that I need for my work and for securing a childcare position. A few days later I heard that my combined trisomy risk is 1:11 600 for T13 and 1:20 000 for the others.

So, there we are. So far, things look good. Now another three weeks until my next check-up, and another seven weeks until the big anomaly scan.

12w0d

Everything looks great. We have a wriggling 6.5 cm fetus with a 1.5 mm NT measurement. Arms, legs, brain, heart, etc all look good Details and pictures to follow.

11w3d: Exhausted

In exactly four days time I will be making my way to the hospital for my NT scan. I am scared of all the things that can go wrong, and excited about what a milestone it will be if everything looks good.

So in order to get me into the spirit of the occasion, I have been doing what any good scientist would do, and reading through the literature surrounding the tests that will be conducted at this appointment, mainly, the NT scan and the blood tests.

The nuchal translucency (NT) test measures the thickness of the sack of fluid behind the neck of the fetus. In general, a fetus with a trisomy (three copies of a chromosome, rather than two) has a thicker NT than a chromosomally normal fetus.

The first figure below illustrates this observation. Each black dot represents two measurements (the crown-rump length and the NT thickness) of a single fetus that was subsequently found to have trisomy 21 (Down's Syndrome). The dark grey rainbow is the distribution of 90% of chromosomally normal fetuses. As you can see, in normal fetuses the NT thickness gradually gets thicker as the fetus gets larger. However, in trisomy 21 fetuses, the thickness remains relatively constant during this gestational period, with a mean thickness of 3.4 mm.

(from Kagan, et al., Ultrasound Obstet Gynecol 2008; 31: 618-624)

The second test is a blood test of the mother to measure our old friend beta-human chorionic gonadotropin (beta-hCG) as well as pregnancy-associated plasma protein-A (PAPP-A). The values on the axis are multiples of the median (MoM), that is, by how many-fold does a result differ from the median value from all normal women. By definition, the median beta-hCG for unaffected pregnancies is 1.0, and the median PAPP-A for unaffected pregnancies is also 1.0.

This second figure below shows how the blood tests from women with trisomy 21 fetuses varies from women with chromasomally normal fetuses. Each dot represents the values from a single patient with a trisomy 21 fetus. The unfilled oval represents the lab values of 90% of women with chromasomally normal fetuses. The median beta-hCG values were 2-fold higher and the the PAPP-A values were 2-fold lower in women with trisomy 21 fetuses.

(from Kagan, et. al., 2008, Ultrasound Obstet Gynecol, 31: 618-624)

So here's hoping that all my dots fall in the normal range, and I can pass this test and start to look forward to moving into the second trimester. It is still feeling unreal, so I hope that seeing a wiggling little fetus on the ultrasound next Tuesday will put some of my anxiety to rest.

References:

Kagan, K.O., Wright, D., Baker, A., Sahota., D., & Nicolaides, K.H. 2008. Screening for trisomy 21 by maternal age, fetal nuchal translucency thickness, free beta-human chorionic gonadotropin and pregnancy-associated plasma protein-A. Ultrasound Obstet Gynecol., 31: 618-624