What Is Uterine Inversion?

Introduction

What is uterine inversion? Join us throughout this article to learn about one of the most serious complications that can arise from childbirth. Uterine inversion is a condition that occurs when the upper part of the uterus, also called uterine fundus, collapses into the uterine cavity and is pulled down through the cervix into the vaginal canal. In simple terms, the uterus turns inside out during delivery. Estimated to complicate one in every two thousand births among both vaginal and caesarean procedures, uterine inversion is a rare occurrence that can potentially be a life-threatening condition due to the high risk of bleeding and shock.¹

Understanding uterine inversion is pivotal for reasons that range from the importance of early diagnostics to the awareness of pregnant women. Empowering soon-to-be mothers and their healthcare providers grants the best practices for preventive measures and prompt medical interventions. Informed decision-making during labour and delivery can avoid potentially life-threatening complications. 

Anatomy of the uterus

Overview of the female reproductive system

To better grasp how this condition represents a serious deviation from the typical anatomy of the uterus within the female reproductive system and its implications for feminine health, it is vital to revisit the central role played by the uterus. A set of organs, including the ovaries, fallopian tubes, uterus, cervix, and vagina, constitute the female reproductive system.² With its physiological functions governed by hormones throughout a woman’s lifetime, the goal of the female reproductive system is conception, pregnancy, and consequent childbirth.

Structure and layers of the uterus

Also usually referred to as “the womb”, the uterus is a pear-shaped organ placed within the lower abdomen that houses the developing embryo or fetus during pregnancy. As a cavity, the uterus’ walls consist of three main layers:

• Endometrium: this innermost layer is where a fertilised egg attaches and grows during the pregnancy months. In case no fertilisation occurs within a menstrual cycle, this layer thickens and sheds, resulting in menstruation.
• Myometrium: as the middle layer, the myometrium is mainly composed of muscle tissue that controls childbirth contractions responsible for pushing the baby out of the uterine cavity
• Perimetrium: finally, the outermost layer is a thin protection that wraps the organ

The normal position of the uterus

Considering the typical anatomy of the female reproductive system, the common uterine orientation presents its upper part pointing towards the front of the woman’s body. A slight tilt forward in the uterus position allows it to rest on top of the bladder.

Uterine inversion causes

In a setting of imbalance of the normal anatomy of the uterus, there are two factors most associated with the occurrence of uterine inversion: fundal pressure in a relaxed part of the uterine wall and extreme traction provoked by the umbilical cord with a fundal attachment of the placenta.³ 

Primary uterine inversion

Childbirth is the event most associated with uterine inversion, which might happen immediately after the delivery of a baby. It can occur in two possible ways:

• Excessive traction of the umbilical cord: in cases when the placenta is tightly attached to the uterine wall, applying excessive force to the umbilical cord can result in pulling down the top of the uterus and causing it to invert.
• Fundal pressure during the third stage of childbirth: uterine inversion might also be triggered by pressure being too vigorously applied to the top of the uterus by a healthcare provider when trying to help deliver the placenta.  

Secondary uterine inversion

A comprehensive overview of the main triggers of uterine inversion events aids the process of early detection and management. While primary uterine inversion is associated with childbirth, secondary uterine inversion is even less frequent and can be a result of previous procedures or pre-existing conditions such as the following:

• Uterine fibroids: disruption of the usual uterine structure and position due to the growth of benign polyps can make the organ more susceptible to an event of inversion
• Uterine anomalies: an abnormally shaped uterus caused by congenital uterine anomalies might be more susceptible to uterine inversion
• Uterine surgery: an increased risk of uterine inversion can be observed in women who have undergone a few medical interventions like a cesarean procedure or the removal of fibroids or polyps, procedures that can render the uterine wall weaker.

Types of uterine inversion 

Uterine inversion events can be divided into three main types or degrees.³ Identifying their own characteristics is crucial to assess the severity of the case and determine the most adequate health care. In practical terms, the degrees that differentiate each type heavily depend on the extent to which the uterus fundus has passed through the woman’s cervix.

• Incomplete uterine inversion: the uterine fundus presents a halfway process of turning itself inside-out. This condition can further progress and lead to serious complications such as infection and bleeding if left untreated.
• Complete uterine inversion: in the most severe form of uterine inversion, the internal lining of the top of the uterus protrudes through the cervix, making the fundus not palpable via the abdomen. A patient affected might experience severe pain, haemorrhage, and shock, posing a significant threat to the woman’s life.
• Prolapsed uterine inversion: the entire uterus prolapses through the cervical cavity, crossing the vaginal opening (also named vaginal introitus) and leading to a medical emergency. The protrusion of the uterus is an extremely painful and distressful event that can severely damage the organ and increase the risk of infections.

Signs and symptoms

Considering the serious complications that can arise, paying close attention to signs and symptoms that can drive uterine inversion is essential for prompt medical care and treatment when this condition is suspected.¹ These signs and symptoms include:

• Severe pelvic pain: a sudden, intense, and cramp-like low abdominal pain, especially during or soon after childbirth
• Presence of a mass in the vaginal canal: protruding mass or tissue visible at the vaginal opening
• The uterine fundus is not palpable in the abdomen.
• Haemorrhage: this form of severe bleeding can result in shock and death if not timely addressed
• Disproportionate blood loss (shock): heavy vaginal bleeding, accompanied or not by clots, that can lead to shock with a rapid heartbeat, confusion, and low blood pressure

In the long run, an episode of uterine inversion can also render a woman susceptible to infection and anaemia due to the exposure of uterine tissue and severe bleeding, respectively. Last but not least, uterine inversion can be a traumatic incident that heavily impacts a woman’s fertility due to potential damage to uterine walls and provokes a profound psychological impact on the childbirth experience. 

Diagnosis

Diagnosis of uterine inversion can be constituted by three complementary approaches: clinical evaluation, imaging, and differential diagnosis.  

• Clinical evaluation: a healthcare provider will review the patient’s medical history and run a physical examination to assess potential symptoms and examine the pelvic area and vaginal canal for abnormalities such as any visible mass or protrusion.
• Imaging: different techniques aid in visualisation of the uterus and to assess the presence of the uterine inversion and its extent. While a transvaginal ultrasound helps determine whether the inversion episode is complete or incomplete, Magnetic Resonance Imaging, or MRI, provides more detailed imaging in a more challenging diagnosis scenario.
• Differential diagnosis: a few symptoms that uterine inversion shares with other conditions may be confounding factors for diagnosis. Uterine prolapse, fibroids, and polyps are examples that make differential diagnosis necessary. 

Treatment options

With a confirmed diagnosis of uterine inversion, prompt medical intervention is critical. The treatment of choice depends heavily on the patient’s overall health conditions and the severity of the inversion episode.  

First and foremost, regardless of the type or extent of the inversion that occurred, medical care is timely in managing symptoms, stabilising the patient, and addressing complications that can be very serious. 

• Manual uterine replacement: performed under anaesthesia. The replacement is performed by applying pressure on the abdomen, gently pushing the uterus back into its usual position. It’s important to note that contractions create a constriction ring in the cervix, making this manoeuvre more difficult.
• Use of pharmacological agents: medication may be used to either relax or contract the uterine muscles towards repositioning it.
• If surgical intervention is needed, the Huntington procedure aims to restore the uterus’ proper position via laparotomy (surgical incision in the abdominal cavity) 
• Under extensive uterine tissue damage, the complete removal of the uterus – called hysterectomy, might be the last resort. A hysterectomy has a profound impact on a woman’s reproductive and mental health, so this option should be thoroughly discussed with the patient and only left for emergencies.

A complete recovery can be expected when successful treatment is achieved, and the patient can live a healthy life. Under prognosis optics, it is important to stay on top of potential complications such as infection, bleeding, and pain. However, healthcare follow-up after treatment by monitoring these signs, adequately managing pain, and providing emotional support helps ensure the patient’s recovery and well-being. 

In the long run, women of childbearing age should explore fertility options and family planning discussions to assess any impacts that uterine inversion might have had on their fertility. Moreover, counselling and therapy are important tools to address the potential psychological distress caused by a uterine inversion experience.

Summary

Uterine inversion is a rare yet serious disruption of the uterus's usual position when it turns upside down. Varying degrees of uterus displacement categorise the episodes according to the severity of inversion. Early diagnosis coupled with well-prepared and immediate medical attention are timely for successful management and prevention of a life-threatening progression of this condition. While recovery is attainable, awareness regarding potential physical complications and psychological well-being are key to a healthy recovery process. By staying informed, healthcare providers, expectant mothers, and their support teams can work together to minimise its occurrence and ensure the best outcome for mothers and their newborns.