After I learned my anti-Kell titer was 64, putting my infant at risk of alloimmunization, the anxiety I was already feeling over my high-risk pregnancy really took off.
By this time, I had also been diagnosed with insulin-dependent gestational diabetes and complete placenta previa. The news about my anti-Kell antibodies, along with the threat of hemolytic disease of the fetus and newborn (HDFN), was the icing on the cake, so to speak.
I already had two kids at home. They were nine and 13 at the time, so they were plenty old enough to understand that sometimes, there are issues that can interfere with a baby’s health. As a parent, I have always wanted my kids to understand such issues, with an age-appropriate explanation. I wanted to reassure them that everything would turn out fine, and that it was all a matter of staying on top of careful monitoring. My son and daughter both knew that things were under control. I had reassured them, but really, the person I needed to convince the most was myself.
Any alloimmunized pregnancy involves close monitoring. Upon learning of these alloantibodies, every affected mother should have her titers checked. This involves a simple poke in the arm to check the antibody levels. If your titer has reached a “critical” level, further monitoring of the baby will be needed.
Middle cerebral artery (MCA) Doppler ultrasounds are advanced ultrasounds that are often performed weekly to help determine whether a fetus could be developing hemolytic anemia. They also measure blood flow velocity, as a fast blood flow through your baby’s brain may mean your baby could be losing red blood cells. At least three measurements, known as MCA-peak systolic velocity (PSV) “peaks”, are carefully recorded, then adjusted based on gestational age. This results in a multiple of the median (MoM) score.
I was told that an MoM score nearing or passing 1.5 warrants a re-scan within 24 to 72 hours. This score means mild to severe anemia may be occurring, and the only treatment for this prior to 35 to 37 weeks is a fetal blood transfusion. Fetal blood transfusions, which are commonly referred to as intrauterine transfusions (IUTs), are delicate, life-saving procedures. If a fetus has started developing severe hemolytic anemia, it will likely not survive without a transfusion with compatible donor blood. If a fetus has severe HDFN that has progressed to hydrops fetalis , IUTs are less likely to be successful.
What is hydrops fetalis?
Hydrops fetalis is a symptom of an underlying medical condition that affects an unborn baby and can occur with HDFN. In this condition, large amounts of fluid accumulate in the baby’s tissues or organs. If it remains untreated, this abundance of fluid can place stress on the fetal heart and other vital organs.
IUTs should be performed by an experienced maternal-fetal medicine specialist. If the mother is past around 35 to 36 weeks, delivery is typically safer than an IUT. Infants are easier to monitor than fetuses, after all!
MCA ultrasounds have been studied many times in recent years. Overall, they have a false-positive rate of 12%. False-negatives are much less common. There are several factors that can lead to an inaccurate MoM score, including conditions like maternal diabetes, a growth-restricted baby or something as minor as fetal activity MoM scores are only accurate with proper provider technique, as well. Personally, I recommend keeping a dated journal of every MoM score. It is important to take note of every MoM measurement, since they can fluctuate, and you want to avoid an upward trend.
By the time I was 29 weeks along, I’d already changed doctors twice and made it through six MCA scans. All of my MoMs were within a “normal” range. Then, I got a dreaded score that scared me: 1.47.
Cue the anxiety and fear. My doctor did not know 100% whether my baby was becoming severely anemic. The idea of an early delivery terrified me, but I also was not completely confident in my clinic’s experience with IUTs. I contacted an experienced perinatologist in another state who came highly recommended, and I had already developed a trusting rapport with her as a telehealth patient.
In a panic, I called my new doctor and we drafted a plan: my local MFMs would perform another MCA first thing in the morning. If this MCA showed an upward trend, I would travel to Ohio with my family, as we needed to prepare for a possible fetal blood transfusion within just a couple of days. This was indeed serious business, but I felt like I was in good hands.
The next morning, I had a second MCA. The MoM was significantly lower, even with an active baby. My family and I breathed a sigh of relief–likely the loudest, greatest sigh of relief I’d ever uttered in my adult life! The MCA monitoring continued until my 33rd week, when I chose to deliver my baby out of caution.
It is important to make sure your current health care provider is experienced in MCAs and IUTs. Ask them–it is more than fine. Be that patient who walks in with questions written down (thanks a heap, pregnancy brain!) and a plan in place, just in case your baby may need intervention. Undetected anemia is untreated anemia, which can put your baby at a higher risk for complications.
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