Blood Clot Symptoms During Pregnancy: A Story of Missed Diagnosis

Anne shares her story of blood clot symptoms during pregnancy and the impact of a missed diagnosis.

During my pregnancy in 2025, I developed a pelvic vein thrombosis in the 36th week, caused by a venous compression syndrome that had gone unrecognized for months. In pregnancy, venous compression syndrome can occur when the growing uterus compresses major blood vessels, such as the pelvic veins, and restricts blood flow to the heart.

Early Symptoms of Blood Clots During Pregnancy

The symptoms had actually started about three months earlier, when I was around 24 weeks pregnant, and my belly grew bigger. The pattern was so striking that I even called it iliac compression syndrome myself before I had any diagnostics: the symptoms appeared as soon as I sat with my legs bent and improved when I stretched my legs, stood up, or lay down. Iliac compression involves compression of the veins in the pelvis, specifically the iliac veins, and can reduce blood return from the legs. Pregnancy increases the risk for iliac compression syndrome due to increased pressure on the pelvis.

I mentioned this to my obstetrician, and because an ultrasound during pregnancy was difficult with the baby in the way, her suggestion was to assess the vessels properly after pregnancy. Unfortunately, I did not think about the possibility that a blood clot could develop from this, so I simply thought I could manage by avoiding sitting upright until the end of the pregnancy.

Long before the “obvious” signs appeared, I kept feeling suddenly unwell whenever I sat with my legs bent — I would feel faint, weak, nauseous, and as if my circulation was collapsing. It became so bad that I carried a camping chair everywhere with me so I could sit in a more reclined position. Neither my midwife nor my obstetrician was familiar with this type of iliac compression syndrome.

When Pregnancy Symptoms Mask Something More Serious

Looking back, I am honestly shocked by how much I kept reassuring myself that everything was probably “normal.” At 34 weeks pregnant, for example, I was on a five-hour train ride to visit my sister when I suddenly felt somewhat short of breath for about two hours. I considered getting off and going to a hospital at several stops, but in the end, I convinced myself it might just be a panic attack — even though I had never had one before or since. This was never investigated, so I cannot say for certain whether it was a pulmonary embolism (PE) or a blood clot in my lung, but since the iliac vein thrombosis was diagnosed two weeks later, I think it is quite possible that it was a small PE. It is frightening to think how badly things could have ended simply because I did not take myself seriously enough and did not want to “disturb” anyone at the hospital.

Delayed Diagnosis of Pelvic Vein Thrombosis in Pregnancy

In the days before my leg became visibly swollen and blue, I developed strong lower back pain and eventually started vomiting. At first, in the hospital, I was treated for pyelonephritis (a kidney infection), although that did not really fit my complaints. Only afterwards, after reading many personal stories and learning more about iliac vein thrombosis, did I realize that lower back and/or groin pain seem to be common early symptoms.

Even once I was in the hospital, the diagnosis was still delayed by other obstetricians, despite my worsening pain shifting to the left groin, elevated inflammatory markers, the sudden swelling and slightly purple discoloration of my leg, and the fact that I am a physician myself and clearly voiced my suspicion of a blood clot.

When my leg finally became swollen and bluish-purple, I immediately knew what it was. I told the doctor clearly that I was worried about a large blood clot, since the whole leg was swollen, but for reasons I still do not understand, she did not find the leg particularly concerning, and I had to insist on an ultrasound to be organized.

When Other Priorities Delay Critical Care

At the same time, I also had cramps and the baby was in breech position, so the obstetricians were concerned that labor might be starting. I think that focus made it harder for them to realize and accept that I had another serious and urgent problem. Instead, the female colleague who dismissed my concern insisted on attempting an external cephalic version first, which involved applying manual pressure on my abdomen several times to turn the baby into a head-down position, before I finally received the ultrasound for my leg. In hindsight, that could have killed me, with a fresh, untreated, and quite extensive clot in my pelvis underneath.

Diagnosis and Ongoing Impact of a Pregnancy-Related Blood Clot

Later, when thrombosis was finally suspected, an MRI was needed because ultrasound alone was not sufficient to visualize the iliac veins. The MRI confirmed the diagnosis and showed the compression. A coagulation disorder was ruled out, so the likely trigger was the combination of iliac vein compression from the growing uterus and pregnancy-related hormonal changes.

After the MRI in the afternoon, I finally received proper treatment and pain medication. The cramps and vomiting stopped completely — which shows they had only been caused by the pain rather than by labor.

Because the diagnosis was made too late, with the start of blood thinners being delayed, I have been left with a chronic thrombosis. The clot has only partially recanalized, restoring blood flow to about 10–20% so far. I am still injecting anticoagulants, as this is the only blood thinner option besides warfarin that is compatible with breastfeeding. The treatment was extended to one year in the hope that the vein might reopen a bit more, although according to the angiologists (vascular medicine specialists), it is very unlikely that the thrombus will fully dissolve. After that, anticoagulation will most likely be discontinued, since the triggering factors are no longer present and a coagulation disorder has been ruled out.

Luckily, according to the clinical score, I do not currently have post-thrombotic syndrome. My leg does not swell, and I do not have cramps or paresthesia. However, vascular testing shows that the venous return on the affected side is still significantly slower than on the healthy side. In daily life, I notice this clearly: I wear compression stockings from morning until evening, taking them off only for showering, because it feels uncomfortable — a mix between pain and heaviness — when I am upright without them.

Advocating for Yourself When Symptoms Are Dismissed

What makes this especially painful in retrospect is that throughout my pregnancy, I kept telling myself I just had normal pregnancy issues and was probably just being overly sensitive. It was my first pregnancy, and although I had felt truly unwell for months, I assumed other women were simply stronger and coping better than I was. Like many women, I had learned to minimize my symptoms and doubt my own instincts, even when my body was clearly warning me that something was wrong.

Looking back, the delayed diagnosis was not only a medical failure, but also part of a larger pattern in which women’s symptoms are too often dismissed by others, and eventually by themselves.

I want to share my story to raise awareness of the increased risk of blood clots during pregnancy, including rare and easily missed presentations. More than that, I want other women to know that if something feels off, they should trust that feeling, keep asking questions, and keep pushing until someone listens. Trusting your gut is not being dramatic — it can be lifesaving.

If you have questions you might like to ask Anne about her experience, she has graciously offered to address them. You can send your questions to [email protected] and we will connect you with Anne directly.