Uterine scarring is a histologically altered section of the uterine wall formed after its damage during surgical and diagnostic interventions or injuries. In non-pregnant women, it is not clinically manifested. During gestation and childbirth, it may be complicated by a rupture with the corresponding symptoms. To assess the condition of scar tissue, hysterography, hysteroscopy, ultrasound of the pelvic organs are used. In case of a threatening rupture, methods of dynamic monitoring of the fetal condition (CTG, Dopplerography of uteroplacental blood flow, ultrasound of the fetus) are recommended. Pathology is not subject to treatment, but is one of the key factors influencing the choice of natural or operative delivery.
General information
According to various data, in recent years the number of pregnant women with a scar on the uterus has increased to 4-8% or even more. On the one hand, this is due to a more frequent cesarean delivery (in Europe and the USA — up to 20%). On the other hand, thanks to the use of modern surgical techniques, the reproductive capabilities of women with diagnosed uterine fibroids or anatomical abnormalities of this organ have improved. In addition, if there are indications, gynecologists are increasingly deciding on the husking of fibroids at the 14th-18th week of pregnancy. The high probability of complications of pregnancy and childbirth in the presence of uterine scarring requires a special approach to their management.
Causes
Uterine scarring occurs after various traumatic effects. The most common reasons for the replacement of muscle fibers of the myometrium with scar tissue are:
- Caesarean section. Planned or emergency delivery is surgically completed by suturing the incision. To date, this is the most common cause of scarring on the uterus.
- Gynecological operations. Scar tissue in the uterine wall is formed after myomectomy, tubectomy during ectopic pregnancy, reconstructive plastic surgery with the removal of the rudimentary horn of the bicorn uterus.
- Rupture of the uterus in childbirth. Often, when the body or cervix ruptures with the transition to the internal pharynx, a decision is made to preserve the organ. In this case, the wound is sutured, and after its healing, a scar is formed.
- Damage caused by invasive manipulations. Perforation of the uterine wall can result in surgical abortion, diagnostic curettage, much less often — endoscopic procedures. After such damage, the scar is usually small.
- Abdominal injury. In exceptional cases, the integrity of the uterine wall is violated by penetrating wounds of the abdominal cavity and pelvis during road accidents, industrial accidents, etc.
Pathogenesis
The formation of a scar on the uterus is a natural biological process of its recovery after mechanical damage. Depending on the level of general reactivity and the size of the incision, rupture or puncture, the healing of the uterine wall can occur in two ways — by restitution (full regeneration) or substitution (incomplete recovery). In the first case, the damaged area is replaced by smooth muscle fibers of the myometrium, in the second — by coarse bundles of connective tissue with foci of hyalinization. The probability of formation of a connective tissue scar increases in patients with inflammatory processes in the endometrium (postpartum, chronic specific or nonspecific endometritis, etc.). It usually takes at least 2 years for the scar tissue to fully mature. The functional viability of the uterus directly depends on the type of healing.
Classification
The clinical classification of uterine scarring is based on the type of tissue with which the damaged area was replaced. Specialists in the field of obstetrics and gynecology distinguish:
- Wealthy scars are elastic areas that are formed by the fibers of the myometrium. They are able to contract at the moment of contraction, are resistant to stretching and significant loads.
- Untenable scars are poorly elastic areas formed by connective tissue and underdeveloped muscle fibers. They cannot contract during contractions, are unstable to rupture.
When determining the examination plan and obstetric tactics, it is important to take into account the localization of scars. Scar-altered may be the lower segment, the body, the neck with an area adjacent to the inner pharynx.
Symptoms of uterine scarring
Outside of pregnancy and childbirth, cicatricial changes in the uterine wall are not clinically manifested in any way. In the late gestational period and childbirth, the untenable scar may disperse. Unlike the primary rupture, the clinical manifestations in these cases are less acute, and some pregnant women may have no symptoms at the initial stage. With the threat of repeated rupture in the prenatal period, a woman notes pain of varying intensity in the epigastrium, lower abdomen and lower back. A depression can be felt on the wall of the uterus. As the pathology worsens, the tone of the uterine wall increases, bloody discharge from the vagina appears. Touching the pregnant woman’s stomach is sharply painful. A sharp deterioration in well-being with weakness, pallor, dizziness, up to loss of consciousness, indicates the completed rupture along the scar.
The rupture of an old scar during childbirth has almost the same clinical signs as during pregnancy, however, some features of the symptoms are due to labor activity. With the onset of scar tissue damage, contractions and attempts intensify or weaken, become frequent, irregular, stop after the rupture. The pain felt by a woman in labor during labor does not correspond to their strength. Fetal movement along the birth canal is delayed. If the uterus is torn along the old scar with the last attempt, there are no signs of a violation of the integrity of its wall at first. After the separation of the placenta and the birth of the afterbirth, the typical symptoms of internal bleeding increase.
Complications
Uterine scarring wall causes anomalies in the location and attachment of the placenta — its low location, presentation, tight attachment, increment, ingrowth and germination. In such pregnant women, signs of fetoplacental insufficiency and fetal hypoxia are more often observed. With a significant size of the scar and its localization in the isthmic-corporeal department, the threat of placental abruption, spontaneous abortion and premature birth increases. The most serious threat to pregnant women with cicatricial changes in the uterine wall is the rupture of the uterus during childbirth. Such a pathological condition is often accompanied by massive internal hemorrhage, DIC syndrome, hypovolemic shock and, in the vast majority of cases, antenatal fetal death.
Diagnostics
The key task of the diagnostic stage in patients with a suspected uterine scarring is to assess its viability. The most informative methods of examination in this case are considered:
- Hysterography. The insolvency of scar tissue is evidenced by the altered position of the uterus in the pelvic cavity (usually with its significant forward displacement), filling defects, thinning and jagged contours of the inner surface in the area of a possible scar.
- Hysteroscopy. In the area of scarring, there may be retraction, indicating thinning of the myometrium, thickening and whitish coloration in the presence of a large array of connective tissue.
- Gynecological ultrasound. The connective tissue scar is characterized by an uneven or intermittent contour, the myometrium is usually thinned. A lot of hyperechoic inclusions are detected in the uterine wall.
The data obtained during the research are taken into account when planning the next pregnancy and developing a plan for its management. From the end of the 2nd trimester, such pregnant women perform ultrasound of the scar on the uterus every 7-10 days. Ultrasound of the fetus, dopplerography of placental blood flow are recommended. If a threatening scar rupture is suspected in childbirth, the shape of the uterus and its contractile activity are evaluated with the help of an external obstetric examination. During ultrasound, the condition of the scar tissue is determined, areas of thinning of the myometrium or its defects are revealed. Ultrasound examination with dopplerometry and cardiotocography are used to monitor the fetus. Differential diagnosis is carried out with threatening abortion, premature birth, renal colic, acute appendicitis. In doubtful cases, an examination by a urologist and a surgeon is recommended.
Treatment
Currently, there are no specific ways to treat scarring on the uterus. Obstetric tactics and the preferred method of delivery are determined by the condition of the scar zone, the peculiarities of the course of the gestational period and childbirth. If during the echography it was determined that the fetal egg was attached to the uterine wall in the area of the postoperative scar, the woman is recommended to terminate the pregnancy using a vacuum aspirator. If the patient refuses an abortion, regular monitoring of the state of the uterus and the developing fetus is provided.
Independent childbirth with a scar on the uterus is recommended for women with one previously undergone cesarean section performed through a transverse incision. Mandatory conditions for choosing in favor of natural delivery are uncomplicated pregnancy, the consistency of scar tissue, the normal functioning of the placenta and its attachment outside the zone of scarring, the head presentation of the fetus, its compliance with the size of the mother’s pelvis. In such cases, a pregnant woman is hospitalized at 37-38 weeks of pregnancy for a comprehensive examination. To improve the prognosis with the onset of labor, the appointment of antispasmodics, antihypoxic and sedative drugs, and means to improve fetoplacental blood flow is indicated.
Surgical delivery is recommended for patients with a high risk of repeated rupture. Direct indications are:
- Longitudinal scar. The probability of scar tissue divergence after dissection of the uterine wall in the longitudinal direction is several times higher than with transverse incisions.
- The presence of more than one scar. If a woman has had more than one Cesarean section, the pregnancy is completed surgically.
- Some gynecological interventions. Conservative myoectomy of the node on the posterior wall of the uterus, reconstructive plastic surgery for abnormalities of uterine development and surgery for cervical pregnancy are contraindications to natural childbirth.
- Previously transferred rupture of the uterus. If the previous birth was complicated by a rupture of the uterine wall, the next pregnancy is completed by caesarean section.
- Failure of the scar. If diagnostic signs of the predominance of coarse-fibrous connective tissue in the scar area are detected, an operation is performed.
- Pathology of the placenta. Surgical delivery is indicated with placenta previa or its location in the scarring zone.
- Clinically narrow pelvis . The loads that occur during the passage of a fetus whose dimensions do not correspond to the pelvis of a woman in labor, as a rule, provoke a repeated rupture.
If, during spontaneous labor, a woman in labor with a scar on the uterus has a threat of rupture, a caesarean section is performed in an emergency. After the operation, the defect of the uterine wall is sutured. Extirpation of the uterus is carried out only with extensive injuries with the impossibility of suturing or the occurrence of massive intraligmental hematomas.
Prognosis and prevention
Choosing the right obstetric tactics and dynamic monitoring of the pregnant woman minimizes the likelihood of complications during pregnancy and during childbirth. For a woman who has undergone cesarean section or gynecological surgical interventions, it is important to plan pregnancy no earlier than 2 years after surgery, and when it occurs, regularly visit an obstetrician-gynecologist and follow his recommendations. To prevent repeated rupture, it is necessary to ensure a competent examination of the patient and constant monitoring of the scar, to choose the optimal method of delivery, taking into account possible indications and contraindications.
