By Laura Rollán Guilén BSc (embryologist).
Last Update: 04/15/2014

One in every three pregnant woman presents spotting or slight bleeding during the first quarter of gestation. It can be due to a minor problem or, conversely, it may indicate that something is going wrong. One of the most common causes of bleeding during early pregnancy are the so-called intrauterine hematomas.

The different sections of this article have been assembled into the following table of contents.

What are intrauterine hematomas?

They are crescent- or wedge-shaped structures located between the chorionic tissue and the uterine wall or the fetal membranes (between the tissue created for pregnancy and the most superficial layers of the uterus). They appear as small blood pools seep within the endometrium, that is to say, among the layers of the uterus. Depending on their location, they are subdivided into:

  • Retroplacental
  • Subchorionic
  • Marginal
  • Supracervical

Causes of intrauterine hematomas

  • Alterations in the development of the trophoblast (single layer which provides the embryo with nutrients; it develops as an important part of the placenta) and the spiral arteries responsible for the nourishment of the placenta.
  • Mechanical factors.
  • Autoimmune factors.
  • Hematologic factors.

Prognosis of intrauterine hematomas

Usually, the pregnant woman detects a slight bleeding and, therefore, she visits the gynecologist. Then, the expert may carry out an ultrasound in order to check the fetus state. In case there is no bleeding, the hematoma may be detected during routinely ultrasounds.

If there is a hematoma, pregnancy may be considered at high risk. Therefore, rest is recommended as a preventive measure. In this situation, the health care provider will monitor the pregnant woman during her pregnancy. Intrauterine hematomas do not usually lead to pregnancy loss. They might be reabsorbed and, then, disappear. However, if the hematoma is very large, it will take longer to heal and the bleeding will be extended.

This injury’s prognosis is based upon two main elements: its location and its size.

Grades of severity

A small or not too big hematoma, which is not accompanied by other symptoms, usually presents a favourable development and, therefore, it is not a symptom of threatened abortion. As pregnancy develops, circulation returns to normal, and most hematomas gradually disappear.

A large hematoma located in the wrong place -such as central, large retroplacental hematomas, in which the division between the chorionic tissue and the decidua basalis (layers surrounding the placenta) occurs- may cause placental abruption or prelabor rupture of membranes, leading, thus, to abortion or premature labour during late gestation.

If you have been detected this injury, it is important to follow your doctor’s directions, which are usually getting plenty of rest, refraining from sexual activity, and, in some cases, taking progesterone.

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Authors and contributors

 Laura Rollán Guilén
Bachelor's Degree in Biology from the University of Valencia (UV). Specialist in Human Assisted Reproduction. Writer of scientific contents. More information
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