Hegar Sign

Hegar sign is a non-specific indication of pregnancy that is characterized by the compressibility and softening of the cervical isthmus (i.e., the portion of the cervix between the uterus and the vaginal portion of the cervix). It typically presents between the fourth and sixth week of pregnancy and may be present until the 12th week of pregnancy. The Hegar sign is not a definitive indication of pregnancy, and the absence of it does not exclude a potential pregnancy. 

Other non-specific indications of pregnancy that can present between the fourth and eighth weeks of pregnancy are the Goodell and Chadwick signs. The Goodell sign is characterized by the softening of the cervical area. Whereas the Chadwick sign is typically characterized by a bluish discoloration of the cervix, vagina, and vulva due to an increase in venous blood flow to the area.

The Hegar sign is typically caused by various physiological changes that occur during the first six weeks of pregnancy. In early pregnancy, increased blood flow, estrogen, progesterone, and prostaglandin synthesis as well as other biochemical changes may alter cervical tissue composition. More specifically, these changes often lead to reductions in collagen concentration and an increase in dermatan sulfate proteoglycans in the cervical tissue, resulting in softening of the cervical isthmus, or Hegar sign.

The Hegar sign can be physically assessed by a medical professional through a bimanual examination in which two fingers of one hand are inserted into the vagina and two fingers of the other hand apply pressure externally to the abdomen in order to palpate the lower uterine segment. During bimanual palpation, the consistency of the lower uterine segment may feel soft compared to the body of the uterus situated above and cervix situated below. 

Hegar sign is a non-specific indication of pregnancy characterized by the compressibility and softening of the cervical isthmus. The Hegar sign usually presents during the fourth to sixth week of pregnancy and may be present until the 12th week of pregnancy. Hegar sign is typically a result of the various changes to the consistency of the cervical isthmus during the first six weeks of pregnancy. It can be physically assessed by a medical professional by bimanual examination in which the consistency of the lower uterine segment may feel soft when compared to the body of the uterus situated above and cervix situated below.