Ask-the-Experts is a resource for healthcare providers that enables a user to submit a question to the Foundation's Board and Medical Advisory Committee. These are researchers and educators at the top of their respective fields. Members include specialists in hemostasis, thrombosis, sickle cell, obstetrics/gynecology and genetic counseling.

If you are a healthcare provider and have a question for one of our experts, click here to SUBMIT YOUR QUESTION. All Ask-the-Expert users must first read and agree to the conditions of Terms of Service.  

*Please note that our experts are unable to provide advice for specific patients, and are only available to answer questions from their colleagues. 


Read below to see an example of a question from a reader and the answer provided by a member of our elite team of blood disorder experts and professionals! To read more questions and answers, please click here to view our Ask-the-Expert Archive.

We have a woman, approximately 30 weeks pregnant and the father has documented severe VWD. We realize the mother is not at an increased risk for extraordinary bleeding but would this be considered a high risk pregnancy due to 50/50 risk of baby having VWD? 

Providers at an HTC

The baby is, as you say, at 50/50 risk for VWD, but not severe - only mild or mod. The OB should avoid operative vaginal delivery and scalp electrode. (No one does scalp sampling any more.) If the patient is in the third stage of labor and at a point of "no return" with fetal distress, the OB should choose forceps over vacuum, otherwise have a low threshold for C/S. Otherwise, C/S should be used for obstetric reasons only.

The OB should get two tubes of cord blood, light blue topped, so that studies can be run on the infant. Is it a girl or boy? If a boy, circumcision should be postponed until his status is known with respect to VWF/FVIII.

Andra James, MD, MPH
Director/Founder of the Women's Hemostasis and Thrombosis Clinic
Duke University Medical Center
Professor of Obstetrics & Gynecology
Duke University School of Medicine
Durham, NC


When someone gets a clot in pregnancy, do you anticoagulate them for the entire time, or do you anticoagulate them for 6 months and then switch to thromboprophylaxis? Also, do you ever ultrasound their legs or lungs to see what the clot is doing in order to choose?

Helen Feltovich, MD, Maternal-Fetal Medicine
Intermountain Healthcare, Provo, UT

At our institution, we fully anticoagulate a patient who gets a clot in pregnancy throughout pregnancy and for at least three months postpartum (PP), usually six months PP. We know from studies of clot incidence that there is still signal related to the increased incidence surrounding pregnancy as far out as three months. We do not image them until we are making a decision to stop anticoagulation and that is usually six months PP. I say "we," but at that time it is our Heme/Coag team who is making the decision. They will also check a d-dimer and assess other risk factors when deciding whether to stop or continue. In Europe, our heme/epi colleagues are concerned about the high rate of recurrence among their patients who receive low dose anticoag for a history of clot, let alone for a clot during that pregnancy. I just have been asked to participate on a steering committee for an international randomized trial of low vs. full dose anticoag for women with a history of clot. My impression is that the risk of recurrent clot is MUCH higher among women who have had a clot during that pregnancy. I am just not comfortable reducing a woman's anticoag to a low dose when she has had a clot during pregnancy, especially when all the risk factors that gave her a clot in the first place are still present. Then, PP, her risk increases another 5- to 20-fold higher than it was during pregnancy.

Andra James, MD, MPH
Founder of the Women's Hemostasis and Thrombosis Clinic
Duke University Medical Center
Associate Professor of Obstetrics & Gynecology
Duke University School of Medicine
Durham, NC


Hello, I had a question regarding oral contraception use in young women with essential thrombocytosis. They have an inherent thrombotic risk. We usually recommend IUD. If this is not possible, do you have any thoughts in regards to which (if any) OCP to use in this patient population. I was also wondering if you would advise medroxyprogesterone acetate (DMPA)? Thank you.

Caroline Cromwell, Assistant Professor Hematology
Mount Sinai School of Medicine

In general, combined oral contraceptives increase risk of thrombosis in susceptible women. Medroxyprogesterone acetate (DMPA) has also been shown to increase risk of thrombosis about 2-fold (so similarly). We usually recommend levonorgestrel releasing IUD or copper IUD for patients where we are concerned about thrombosis risk. The other alternative for an oral agent is the mini-pill, but some women don't tolerate side effects. If the patient chooses barrier methods, be sure she uses two things (e.g., condoms and spermicide).

Mary Cushman, MD, M.Sc.
Professor of Medicine, Hematology/Oncology Division
Department of Medicine
Professor of Pathology
University School of Vermont
Durham, NC


I have been following a wonderful young woman since she was 16-years-old. She has sickle cell disease and had 2 strokes the last being in 2006. She was treated with simple transfusion protocol; however, IV access became a problem. We placed a pheresis port and she has been successfully exchanged by Red Cross every three weeks with no complications. She graduated from college and because we could not find another center to continue the pheresis in Charlotte, she stayed in our clinic and is working to complete her Masters in Social Work.  Ferritin is 1500. She is now 26 weeks pregnant. I have been trying to find any experience of continued exchange transfusions through third trimester without much luck. In addition, we performed a thrombophilia evaluation last week. Patient is heterozygous for Factor V Leiden with Protein S of 24%. Factor 8-199% and Factor 5-174%. Homocysteine level is normal and no prothrombin mutation.So far, the baby is doing well and our patient is doing well. She is followed by Maternal Fetal at Novant Health Presbyterian Main Hospital in Charlotte. My plan is to continue exchange transfusions until delivery to maintain S below 30%. Concern for prethrombotic environment with the viscosity of simple transfusions may compromise placental perfusion. With the new findings of heterozygous Factor V Leiden and Protein S, and a history of presumed sickle cell related strokes, would the experts recommend additional treatment: Low dose heparin, Lovenox, etc.? Do they agree with the continued pheresis? Yes or No, and why? Thank you so much, and I would be glad to add any additional information they may need. 

Paulette Bryant MD
Charlotte, NC

This is a complicated clinical scenario. In addition, there is very little published literature in this area.  However, we have been concerned about the potential hemodynamic/intravascular pressure shifts that may exist during exchange and the impact on the fetus. We have used straight transfusions during the pregnancy then resumed exchanges postpartum. However, our patients did not have other thrombotic risk factors and they did well. I understand your concern regarding thrombotic risk and potential compromise to fetal growth. I like your plan to continue exchanges and monitor closely.

Sickle cell disease is a high-risk thrombophilia, as pointed out by Sophie Lanzkron and colleagues in their recent articles. Given this patient's additional risks of pregnancy, FVL, low protein S and history of stroke, I would think that at least low-dose LMWH plus ASA, or a moderate dose of LMWH, with heparin in the peripartum period should be considered, in addition to the standard treatment you and Kim have discussed.

What a challenging case!


Kim Smith-Whitley, MD
The Children's Hospital of Philadelphia
Philadelphia, PA

Andi James, MD, MPH
University of Virginia
Charlottesville, VA