Reproductive Health & Endometrial Trauma

Learn About the Anatomy of the Uterus

What is the Uterus?

The uterus, sometimes called the womb, is the hollow pear-shaped organ located in the female pelvis that is attached to the top of the vagina, and to the fallopian tubes which serve as the meeting place for sperm and egg. It comprises a top portion (the wide part of the pear) called the uterine corpus, and a narrow part, called the cervix.

What are the Endometrial Cavity and the Cervical Canal?

The endometrial cavity is the space within the uterine corpus that is the resting place for a developing pregnancy. The endometrial cavity can be thought of as a triangle pointing “down” with two tiny openings in the top two angles connecting with the fallopian tubes, and below, a larger but still small opening that connects with the cervical canal. The cervical canal is a narrow channel within the cervix that starts with the endometrial cavity and ends by opening into the top of the vagina. This canal allows sperm to gain access to the endometrial cavity, for menstruation to exit the endometrial cavity, and, following dilation, for the expulsion of a baby during the process of labor.

What is the Endometrium?

The endometrium is the lining of the the endometrial cavity. The top layer of the endometrium (“functional layer”) is shed with each normal menstrual period, and then regenerates every month from the bottom layer (“basilar layer”) under the hormonal control of estrogen and progesterone originating from the ovary. The purpose of the endometrium is to allow the very early pregnancy (the embryo) to implant and grow and also serve as an interface between what will become the placenta and the muscular wall of the uterus called the myometrium. After delivery of a baby, the intact basilar endometrium allows the placenta to separate from the uterus allowing the myometrium to contract and stop the bleeding that normally occurs. Weeks to months after pregnancy, when the ovary resumes function, the intact basilar endometrium regenerates the functional layer and menstrual periods resume. This process is typically delayed by breastfeeding or the use of contraceptive methods that contain progestins with or without estrogens.

This Figure shows simplified uterine anatomy and physiology. Depicted is the normally pear-shaped uterus situated anterior to (in front of) the colon, posterior to (behind) the bladder, and attached to the vagina. The hollow organ includes a corpus, primarily comprising specialized muscle (myometrium), lined by a layer of tissue called the endometrium, and a cervix, connecting the endometrial cavity to the vagina via the cervical canal. After conception, the embryo is transferred via the fallopian tube to the endometrial cavity, where it attaches to and is then enveloped by the endometrium, where, as a fetus, it develops until reaching maturity. At that point, in the process of labor, it is expelled from the endometrial cavity by dilation of the cervical canal and contractions of the muscular uterine corpus. If a pregnancy does not occur, the superficial portion of the endometrium, the functionalis, is discharged during menstruation.

Endometrial Trauma & Intrauterine Adhesions (IUAs)

  • The endometrial trauma of concern is that which results in damage to the basilar layer of the endometrium, as it is not regenerated, allowing for the formation of IUAs, The causes of the trauma are almost always medical procedures that affect the endometrium, most commonly related to pregnancy, but, perhaps paradoxically, also those operations that are designed to improve the chances of pregnancy. The most common pregnancy related procedures are pregnancy termination, and “D&C” to remove parts of a pregnancy not expelled following miscarriage or delivery. Operations designed to improve fertility can include myomectomy (removal of fibroid tumors) or division of a congenital abnormality called a septum. Infections, most commonly tuberculosis, are relatively common causes of endometrial trauma and IUAs in parts of Africa and South Asia, but are rarely identified in developed countries.

  • Intrauterine adhesions (IUAs), also known as Asherman syndrome, are an acquired condition where scar tissue (adhesions) form inside the uterus following medical procedures that involve and traumatize the inner lining called the endometrium.

  • Endometrial trauma is what causes IUAs by allowing damaged areas on either side of the endometrial cavity to stick to one another that ultimately forms the adhesions – basically “scarring” gone wrong.  It is important to understand that removal of the IUAs will restore the shape and volume of the endometrial cavity, but often dp not treat the endometrial trauma. That may remain and cause clinical problems related to pregnancy. The severity of adhesions may range from mild and essentially irrelevant, to severe, reflecting extensive trauma to the basilar layer of the endometrium.

  • As previously described, if there hasn’t been an intrauterine procedure, endometrial trauma will not occur and neither will IUAs. Most with endometrial trauma have no symptoms. If IUAs develop and are either extensive or located in particular locations, menstrual bleeding may reduce in volume, and in some cases become absent altogether, a symptom called “amenorrhea”. Some may develop pain with menstrual periods. For those trying to conceive, infertility or recurrent pregnancy loss may result.

  • There are 3 approaches to prevention of endometrial trauma:

    1. Avoidance of procedures that traumatize the endometrium.

    2. If a procedure is needed, use of techniques that reduce the trauma and interventions designed to allow endometrial healing and prevention of IUA formation (Primary Prevention).

    3. If adhesions have already occurred, and division of adhesions is needed, use of technique and interventions designed to facilitate endometrial healing and reduce the risk of reformation of IUAs (Secondary Prevention).

  • The standard treatment for IUAs is a surgical procedure where the adhesions are visualized with a hysteroscope (a special type of telescope) passed through the cervix, followed by division of the adhesions usually with scissors – a process called hysteroscopic adhesiolysis Because the adhesions can reform, more than one adhesiolysis may be needed – this occurs variably, from 3% to 62.5%, depending on the severity of the adhesions at baseline. At the present time, there are no devices or medications approved by the US Food and Drug Administration (FDA) for the prevention of endometrial trauma and IUAs following procedures involving the endometrium.

  • When it is necessary to perform removal of tissue from the uterus following pregnancy different techniques are being developed, many using hysteroscopy, to reduce the endometrial trauma associated with the procedures.

    Researchers have developed materials to place within the endometrial cavity following surgery to separate the endometrial surfaces during the early healing period. These materials, known as intrauterine barriers or “spacers” may require later removal, or dissolve in one to three weeks following placement, when the endometrium has had a chance to heal without the formation of adhesions

    Other research is evaluating means by which endometrial growth can be stimulated, including the use of the “stem cells’ which potentially could be designed to replace endometrium that has been damaged beyond repair.

Endometrial Trauma Committee

  • Bala Bhagavath, MD

    Dr. Bhagavath’s extensive experience includes infertility treatments of all types, including ovulation induction, intrauterine insemination and in vitro fertilization. He is a nationally recognized surgeon with special interest in minimally invasive surgery including robot assisted surgery and offers this service for tubal anastomosis, fibroids, endometriosis and developmental anomalies of the genital tract. He is the Director of the Fellowship in Minimally Invasive Gynecologic Surgery program and is co-director of the University of Rochester Medicine Fibroid Center and Director of Third Party Reproduction.

  • Mark Hans Emanuel, MD

    Dr. Emanuel is a specialist in advanced hysteroscopic surgery. He directs an International Referral Center for advanced hysteroscopic surgery and Asherman Syndrome and was awarded as Dutch Inventor of the Year for the development of Hysteroscopic Morcellation or Tissue Removal Systems. He won several awards from The Society of Reproductive Surgeons and The American Association of Gynecological Laparoscopists. He holds three patents related to Hysteroscopic Morcellation, Gel instillation Sonohysterography and Hysterosalpingo Foam Sonography respectively.

  • Heather Huddleston, MD

    Dr. Heather Huddleston is a specialist in reproductive endocrinology (hormonal function) and infertility. She has special interests in polycystic ovary syndrome (PCOS), recurrent pregnancy loss and uterine disorders, including Asherman's syndrome (a condition involving scar tissue in the uterus). She also has expertise in techniques for diagnosing and treating complex uterine causes of infertility, including hysteroscopy. As director of the University of California in San Francisco PCOS Clinic and research program, Huddleston oversees multiple research projects focused on improving medical understanding of PCOS.

  • Angelo B. Hooker, MD

    Dr. Hooker is an obstetrician and gynecologist at the Zaans Medical Center and Amsterdam UMC Department of Obstetrics and Gynecology. He has published work on topics including recurrent incarceration of the gravid uterus, reproductive outcomes in women with mild intrauterine adhesions, and immediate and long-term complications of delayed surgical management in the postpartum period.

  • Malcom G. Munro, MD, FRCSC, FACOG

    Dr. Munro is a gynecologist, Clinical Professor in the Department of Obstetrics & Gynecology at UCLA, in Los Angeles, and a long time consultant to the medical device and pharma industries, particularly in the gynecology space. He has special interests in radiofrequency electricity, extensive experience in clinical trial design and interpretation, and has aided companies in negotiations with the FDA for regulatory approval.

  • Christina A. Salazar, MD

    Dr. Christina Salazar is a fellowship trained minimally invasive gynecologic surgeon at the University of Texas at Austin Dell Medical School.  Her specialty focus is on advanced hysteroscopic surgery for management of fibroids, Mullerian anomalies, Asherman’s Syndrome, as well as office hysteroscopy and resectoscopy.  Dr. Salazar has served as the Chair of the AAGL Hysteroscopy SIG from 2021 to 2023, and currently serves as a board member on the AAGL MIGS Fellowship Board.  At Dell Medical School, she is actively engaged in research and in teaching MIGS fellows, residents, and medical students.