Abnormally Thickened Endometrium Related to Pregnancy on Ultrasound

Abnormally thickened endometrium related to pregnancy is a common finding when doing ultrasound.   There are normal causes related to early pregnancy to potentially deadly conditions like ectopic pregnancy.  Ultrasound exams routinely evaluate the thickness of the endometrium.

What are some conditions that can result in thickened endometrium in pregnancy?

Early pregnancy before the sac is seen can result in thickened endometrium.  Ectopic pregnancy which is a pregnancy outside the uterine cavity can result in thickened endometrium.  Sometimes there can be fluid in the uterine cavity which we call a pseudo gestational sac.  Ectopic pregnancies are most commonly located in the tubes.  On ultrasound, there will be a cyst or mass next to the ovary. There will often be blood flow around this which we call the ring of fire.

Retained products of conception is another cause of thickened endometrium on ultrasound in pregnancy. This is retained placental or fetal tissue after delivery, miscarriage or termination of pregnancy.    This can present with vaginal bleeding, pelvic pain and fevers. On ultrasound, this presents as thickening of the endometrium or mass.  Often blood flow is present within the abnormal endometrium.

Blood clot within the uterine cavity can result in thickening of the endometrium related to pregnancy.  On real time scanning, actual movement of the blood can sometimes be seen.  On ultrasound, this will result in thickened endometrium without blood flow, unlike retained products.

Endometritis is infection or inflammation of the endometrium.  This can occur following delivery or miscarriage.  On ultrasound, the endometrium will be thickened.  There will be fluid and air within the endometrial cavity.  This is often a clinical diagnosis.  The ultrasound findings can overlap with normal post postpartum findings.

Gestational trophoblastic disease is a name for a group of disorders for which abnormal trophoblast cells proliferate in the uterus after conception.    This is related to trophoblastic cells which help with the pregnancy.  Most are benign tumors but some have malignant potential.  In hydatidiform mole, the trophoblasts proliferate abnormally and form masses.  In gestational trophoblastic neoplasia, the trophoblasts become invasive or cancerous.  The appearance on ultrasound is variable, but can appear as abnormally thickened endometrium.  Beta HCG hormone in the blood will be elevated.

Abnormally thickened endometrium on ultrasound related to pregnancy has many causes.  Many of these causes overlap with each other on ultrasound.  The clinical history and laboratory findings will help narrow the possibilities.