Vena cava syndrome in pregnancy: what it is and how it manifests itself

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Dizziness, paleness, sweating and fainting. These are the most common symptoms associated with supine hypotension syndrome, better known as vena cava syndrome, a circulatory disorder that arises when pressure on the inferior vena cava prevents blood from flowing freely to the heart.

In particular, the vena cava syndrome occurs when the woman, especially in the last stages of pregnancy, lays down on her back and in this way the weight of the uterus rests on the vena cava. The crushing of this important vein leads to a decrease in blood pressure which can lead to dizziness and fainting.

In this article

  • what is the vena cava
  • vena cava syndrome
  • symptoms
  • how to avoid compression of the vena cava

What is the vena cava?

The vena cava is the largest venous trunk we have inside our body and is located in the abdominal cavity. Its function is very important and consists of collect and transport oxygen-poor blood to the heart. "The vena cava is a collecting vein that collects blood from all peripheral veins," explains the Prof. Sergio Ferrazzani, associate professor of gynecology and obstetrics at the Catholic University of the Sacred Heart of the city. "In our body we distinguish the inferior vena cava and the superior vena cava. In particular, the inferior vena cava collects blood from the veins of the lower limbs and abdomen, and carries it to the right side of the heart."

When the inferior vena cava is squeezed, for example by the uterus of a pregnant woman, blood no longer circulates freely and blood pressure decreases. In this case we can talk about vena cava syndrome.

Read also: High blood pressure in pregnancy

Vena cava syndrome in pregnancy

"Vena cava syndrome is a circulatory problem which can occur in pregnant women, especially during the third trimester, "explains the Prof. Maria Teresa , Director of the Operational Unit of Obstetrics and Gynecology of the Hospital of the University of Padua. "It doesn't happen to all women, let's remember, however it can happen that when the expectant mother is in supine position you begin to feel dizzy, dizzy and faint. It happens because the pregnant uterus is able to compress the inferior vena cava and in this way less blood reaches the heart ", he explains.

Vena cava syndrome, or supine hypotension syndrome, most often occurs in the second or third quarter, when the uterus begins to have a considerable weight. "The uterus of a non-pregnant woman weighs about 70 grams, towards the end of pregnancy, however, it weighs 1 kilogram, to which we must add 1 liter of amniotic fluid and over 3 kilos of fetus. This load. compresses the abdominal vessels and it is for this reason that if the woman is in the supine position a lot it is possible that she will faint "says Prof. Ferrazzani.

Read also: Uterus: how it turns in pregnancy and childbirth

Symptoms of vena cava syndrome

Symptoms of supine hypotension syndrome are:

  • drop in blood pressure;
  • dizziness;
  • sweating;
  • nausea;
  • pallor;
  • edema on the legs;
  • fainting
  • rapid heartbeat (tachycardia);
  • difficulty in breathing.
Read also: Low blood pressure in pregnancy

What to do to avoid compression of the inferior vena cava?

Compression of the vena cava occurs when the woman is in a supine position, i.e. lying on her back with the belly up. "As soon as you feel the symptoms, it is appropriate that the woman puts herself in a different position, for example on the side, and the problem is solved "explains the doctor, who then adds" if the woman does not change position, even the fetus can suffer, but generally it does not happen precisely because the woman immediately feels the typical symptoms of this syndrome ".

However, remember that it does not necessarily happen to all women and a lot depends on the size of the uterus and the physical structure of the mother. The advice, however, remains that of do not spend too much time in the supine position and to prefer the position on the right or left side instead.

Sources used:

  • Consultancy by Prof. Maria Teresa, Director of the Obstetrics and Gynecology Unit of the Hospital of the University of Padua;
  • Advice from Prof. Sergio Ferrazzani, associate professor of gynecology and obstetrics at the Catholic University of the Sacred Heart of the city;
  • Guidelines of the Del Paesena Society of Obstetric Gynecological Ultrasound (2022)

  • wellness in pregnancy
  • pregnancy pressure
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