What Is the Cervix?

The cervix is a tube or cone-shaped structure which comprises the lower third of the uterus. Over the course of a woman's lifetime, the cervix undergoes changes in response to cyclical shifts in hormones. This structure is most notably involved in menstruation and delivery of a baby. The cervix is a common location for cancers to develop, so screening for cervical cancer is often recommended on a regular basis so that any signs of cellular changes can be quickly identified and addressed.

Also known as the neck of the uterus, the structure is easy to spot on anatomical drawings, although it is often labeled in a way which suggests that the os, or opening, is the whole cervix. Looking at drawings of the uterus and vagina from the front, the cervix is the narrowed area at the base of the uterus which opens into the vagina. It is important to note that the precise structure of the uterus can vary from person to person, and that small variations are not a cause for concern.

This anatomical structure is made from smooth muscle which forms a tube. During menstruation, the tube enlarges and the os opens so that the endometrium, the lining of the uterus, can be successfully shed. This can take several days. Sometimes "spotting," in which small drops of blood appear throughout the menstrual cycle, can also occur, especially in people who have certain gynecological conditions. During the menstrual cycle, this structure secretes varying amounts of mucus, which plays a role in fertility.

During pregnancy, the cervix stays closed to keep the uterus sealed in order to protect the developing fetus. In the last weeks of pregnancy, it starts to thin in preparation for dilating for labor and delivery. During the process of dilation, it opens wide to allow the baby to move through and into the vagina for delivery. Dilation can be assessed with a quick examination to determine how far labor has progressed. After delivery, the entire uterus will tighten back up to return to its normal size.

In screening for cervical cancer, sometimes false positives are returned. This occurs most commonly because an inflammation or infection has caused abnormalities in the cervical cells which will resolve once the cause of the abnormalities is addressed. When positive results are returned, additional follow up screenings may be recommended to determine whether or not additional action needs to be taken.

The bottom portion of the uterus, or cervix, is at the top of the vagina. It is a cylindrical organ that connects the vagina to the uterus. The cervix is a crucial component of the female reproductive system. It produces cervical mucus that aids sperm in reaching the uterus and fallopian tubes and opens a passageway for menstrual blood to exit the uterus and enter the vagina. Additionally, it acts as an infection-prevention shield between the uterus and the outside world. 

The cervix must be present during birthing. The cervix widens during labor, allowing the baby to pass through the birth canal. The cervix thins and stretches throughout work, forming an opening big enough for the baby to fit through. It is a crucial step in childbirth and is known as effacement. The amniotic sac, which aids in protecting the fetus during labor, is also kept in reasonable condition by the cervix.

The mucosa, submucosa, and muscularis are some of the tissue layers that make up the cervix. The cells that create cervical mucus are found in the mucosa, the deepest layer. The muscularis is a layer of muscle tissue that helps control how the cervix opens and closes. At the same time, the submucosa is a layer of connective tissue that aids in supporting the mucosa. 

A speculum, a device put into the vagina to allow the provider to see the cervix, can be used by a healthcare professional to inspect the cervix. The medical professional might also conduct a Pap smear to look for abnormal cervix cells. During a Pap smear, cells from the cervix are taken and sent to a lab for examination. 

When abnormal cells in the cervix develop out of control, it can lead to cervical cancer. It is the most prevalent female reproductive system cancer, and human papillomavirus (HPV) infection is typically the root of the problem. Vaginal blood, pain during sex, and unusual vaginal discharge are all signs of cervical cancer. Regular cervical cancer screenings can boost the likelihood of successful therapy by assisting in the early detection of this cancer.