Pregnancy of Unknown Location (PUL) or Pregnancy of Unspecified Location is the clumsy term we use for patients during the early days of their IVF pregnancy, when the beta HCG blood test is positive, but it’s too early to do an ultrasound scan to find out whether the pregnancy is in the uterus ( as it is supposed to be), or in the fallopian tubes ( aka ectopic pregnancy).
Early IVF pregnancies are routinely monitored by measuring serial beta HCG values in the blood. Read more at www.drmalpani.com/knowledge-center/articles/hcg. In a healthy pregnancy, HCG values double every 2-3 days, and this is reassuring, and suggests the pregnancy is viable and intrauterine. However, the HCG is just a number, and does not provide all the information we need to assess the health of the pregnancy, or its location.
This is why we need to wait until the HCG level crosses about 1000 mIU/ml—what is called the discriminatory zone, because it allows us to differentiate between an ectopic pregnancy and an intrauterine pregnancy, using vaginal ultrasound. Read more at http://www.drmalpani.com/knowledge-center/articles/atlas-of-ultrasound-images-during-early-pregnancy.
Once the HCG rises to more than 1000 mIU/ml, modern ultrasound machines allow us to see the gestational ( pregnancy) sac inside the uterus. Before this stage, the sac is so small, that it’s not possible to visualize it on an ultrasound scan, which is why there is no point in doing ultrasound scans until the HCG crosses 1000 mIU/ml. In this gray zone, the pregnancy is called a PUL – pregnancy of unspecified ( or unknown) location.
The good news is that most of these pregnancies will be in the uterus, but because it’s important to diagnose the rare ectopic pregnancy as early as possible, we still do need to monitor all IVF pregnancies carefully.
PUL is the term used to describe the clinical scenarios where the pregnancy test is positive, but we are unable to identify a clear intrauterine pregnancy (IUP) or ectopic pregnancy (EP) on transvaginal ultrasound. Patients are clinically fine, and don’t have any symptoms or signs, which is why we need to track blood HCG levels serially.
In some cases, the HCG level declines on its own. This is called a biochemical pregnancy, or a “spontaneous resolving PUL”.
While most patients with a PUL will have a healthy pregnancy, some will be eventually diagnosed with an abnormal pregnancy . This could be either intrauterine ( an early miscarriage), or an ectopic. Read more at http://www.drmalpani.com/knowledge-center/articles/ectopic
The good news is that when the diagnosis is made early, this can be treated safely and easily with medicines.
While the uncertainty surrounding the final outcome of a PUL can be nerve-wracking for a patient, and your heart breaks if the levels drop or you end up having an ectopic, if you understand the medical protocol we follow, it will be much easier for you to handle your emotions. The good news is that the fact that you have got pregnant after your IVF treatment means that your chances of having a healthy baby in the next IVF treatment cycle are much better because embryo implantation has been documented – even if it was in the wrong location, or did not survive to become a baby.
Please get your doubts resolved free using our chatbot which is powered by AI based on Dr Malpani’s 40 years of clinical expertise and experience at https://www.drmalpani.com/chat-w-chatbot/index.html. This will ensure you’re on the right path and potentially save significant costs in the long run.