Uterine tachysystole

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Uterine Tachysystole is a condition of excessively frequent uterine contractions during pregnancy. [1] It is most often seen in induced or augmented labor, though it can also occur during spontaneous labor, [2] and this may result in fetal hypoxia and acidosis. This may have serious effects on both the mother and the fetus including hemorrhaging and death.[ citation needed ] There are still major gaps in understanding treatment as well as clinical outcomes of this condition. [3] Uterine tachysystole is defined as more than 5 contractions in 10 minutes, averaged over a 30-minute period. [1]

Contents

Signs and Symptoms

Excessive contractions may be a sign of placental abruption or obstructed labor potentially leading to Uterine Tachysystole. [3] Fetal hypoxia is often associated with uterine tachysystole as well as neonatal brachial plexus injury.[ citation needed ]

Cause and Correlations

Researchers have determined that uterine tachysystole is not able to be predicted by either demographic or clinical factors, [4] but there are factors that may correlate with the diagnosis. Misoprostol use and high-dose oxytocin use positively correlate highly with uterine tachysystole. [5] Oxytocin is suspected to be a contributor to abnormally increased uterine contractions and uterine tachysystole, but further research is needed for this suspicion to be confirmed. [6] There has been practice of using nipple stimulation to induce labor. However, one study reveals that this may be dangerous because of the uncontrolled release of oxytocin which has shown to correlate to the onset of uterine tachysystole. [7] Prostaglandins, commonly used for initial stages of labor induction or augmentation, have been associated with tachysystole as well as fetal distress. [8]

The presence of uterine leiomyomas have shown to correlate with the incidence of uterine tachysystole. [9]

Antepartum hemorrhage and chorioamnionitis are potential pathological causes for spontaneous Uterine Tachysystole.[ citation needed ] Previous cesarean sections could potentially be a precursor to future uterine tachysystole as well.[ citation needed ] There are no confirmed significant predictors for this condition. [4]

Pathophysiology

The function of the placenta is to act as the lungs and be a vessel of gas exchange for the fetus as this is where oxygen is exchanged for carbon dioxide. [1] In the absence of laboring and contracting, blood flow into the intervillous space results from spiral arterial pressure exceeding intramyometrial pressure, or uterine pressure. [1] During a contraction, uterine blood flow becomes disrupted as myometrial pressure elevates to a higher level than spiral arterial pressure, and this disallows oxygen to reach the fetus through the placenta during these contractions. [1] During normal labor contractions, there is adequate time for a fetus to recover its levels of oxygenation during the relaxation time between contractions. [3]

Contractions that are stronger than normal and have a shortened relaxation time disallow for the placenta to receive adequate levels of blood flow which likely leads to the fetus receiving lower levels of oxygen through the placenta. [3] A contraction with 30 mmHg or more leads to reduced placental blood flow and a potentially hypoxic fetus. [3] The duration of the contraction affects the length of time in which the spiral arteries are compressed, and the strength of the contraction affects the degree of arterial compression. [1] Throughout the laboring processing, this leads to progressive decrease in fetal oxygen saturation and fetal intracerebral oxygen saturation [3] as fetal hypoxia occurs when contractions are either too long or too strong. [1]

The fetal oxygen reserve functions to supply the fetus with the oxygen that it needs to maintain adequate oxygen levels during transient stages of decreased oxygen partial pressure such as during contractions so that the fetus is able to tolerate the contractions. [1] This fetal oxygen reserve is effective during normal laboring, but as contractions become more frequent, there is less and less time for oxygen levels to be replenished which then leads to fetal hypoxia. This reduced relaxation period between contractions also results in an inability to clear acidotic metabolites from the cells which may lead to fetal acidosis. [1]

Fetal pulse oximetry gave researchers the means to quantify the effects that result from uterine tachysystole. [1] In 2008, 1,493 contractions were studied across 30 patients. The conclusion of this study revealed that there is a 6% decrease in fetal partial pressure of oxygen every 8 minutes during uterine tachysystole. [1] The fetus’ oxygen saturation levels begin to deplete within about 5 minutes of the onset of uterine tachysystole and their hypoxic states exacerbated until the UT was able to be stopped. [1] Several other factors may worsen the clinical presentation of uterine tachysystole such as pregnancy or labor complications that compound hypoxia or acidosis in the fetus, a fetus with a already compromised baseline oxygenation due to intrauterine growth restriction, oligohydramnios, and cord compression, and preexisting uteroplacental insufficiency due to hypertensive disorders, post-term pregnancy, or diabetes. [1]

Diagnosis

Uterine Tachysystole is diagnosed upon the presence of several different clinical presentations of a laboring patient. If a patient experiences any of the following presentations during labor, they may receive a diagnosis of Uterine Tachysystole: [1]

  1. The patient experiences more than five contractions in 10 minutes over a 30 minute time period [1]
  2. The patient experiences a series of single contractions with a duration of at least two minutes [1]
  3. The patient experiences contractions with normal duration, but the contractions occur within one minute of each other [1]

Treatment or Management

When fetal distress and hypoxia results from uterine tachysystole, tocolytic medications may be used to attempt to improve the baby’s oxygen levels. There is not sufficient research that gives a clear indication as to which tocolytic drug is safer for the patient. [3] An emergency delivery or cesarean section may also be an effective treatment option, tocolytic drugs are very important in low-resource environments when a C-section may not be available. [3] Methods such as inserting a transcervical foley catheter are also effective in reducing the incidence of uterine tachysystole.[ citation needed ]

Prognosis

Visual depiction of placental abruption Gross pathology of placental abruption.jpg
Visual depiction of placental abruption

Serious effects may result in hypoxic babies that suffer through Uterine Tachysystole such as cerebral palsy, organ damage, acidemia/acidosis, brain damage and death. [3] Some of these consequences may be life-long for the mother or the fetus. [1] Newborns born to mothers that experiences tachysystole were two times as likely to be admitted into NICU. [10] There are also risks that are posed to the mother as well resulting from UT including increased C-section rates, cervical laceration, placental abruption or uterine rupture (for women with history of C-sections), infection, antepartum or postpartum hemorrhage, increased risk of amniotic fluid embolism, and death.[ citation needed ]

Epidemiology

A study of 890 patients revealed that about 11.1% of the sample had a minimum of one episode of uterine tachysystole with the incidence being higher in non-whites. [10] The adjusted odds ratio for UT in Hispanics was about 1.66 with a 95% confidence interval of 1.28-2.05, 1.58 for African Americans with a 95% confidence interval of about 1.05-2.38, and 1.51 for Asians with a 95% confidence interval of about 1.13-2.0. [10] The subjects in the study with uterine tachysystole had a higher usage of epidural analgesia with 62.2% of those with UT having taken an epidural compared to the 40.9% of the subjects in the group without UT having taken an epidural ( p < 0.001). [10] Uterine Tachysystole was found in higher rates among women who had yet to have previously born a viable child as well as in women carrying heavier fetuses. [10]

Research directions

Further research is needed on Uterine Tachysystole with larger sample sizes of women. [3] Future directions of research may include the measure of clinically relevant outcomes for the mother and the baby resulting from Uterine Tachysystole such as death, well-being, and safety of the mother and/or the baby. [3] Future research on the administration of misoprostol is needed so that this medication may be able to be safely administered to induce labor while simultaneously minimizing the risk of developing Uterine Tachysystole. [4]

Related Research Articles

<span class="mw-page-title-main">Misoprostol</span> Medication to induce abortion and treat ulcers

Misoprostol is a synthetic prostaglandin medication used to prevent and treat stomach and duodenal ulcers, induce labor, cause an abortion, and treat postpartum bleeding due to poor contraction of the uterus. It is taken by mouth when used to prevent gastric ulcers in people taking nonsteroidal anti-inflammatory drugs (NSAID). For abortions it is used by itself or in conjunction with mifepristone or methotrexate. By itself, effectiveness for abortion is between 66% and 90%. For labor induction or abortion, it is taken by mouth, dissolved in the mouth, or placed in the vagina. For postpartum bleeding it may also be used rectally.

Fetal distress, also known as non-reassuring fetal status, is a condition during pregnancy or labor in which the fetus shows signs of inadequate oxygenation. Due to its imprecision, the term "fetal distress" has fallen out of use in American obstetrics. The term "non-reassuring fetal status" has largely replaced it. It is characterized by changes in fetal movement, growth, heart rate, and presence of meconium stained fluid.

<span class="mw-page-title-main">Cardiotocography</span> Technical means of recording the fetal heartbeat and the uterine contractions during pregnancy

Cardiotocography (CTG) is a technique used to monitor the fetal heartbeat and uterine contractions during pregnancy and labour. The machine used to perform the monitoring is called a cardiotocograph.

<span class="mw-page-title-main">Gestational hypertension</span> Medical condition

Gestational hypertension or pregnancy-induced hypertension (PIH) is the development of new hypertension in a pregnant woman after 20 weeks' gestation without the presence of protein in the urine or other signs of pre-eclampsia. Gestational hypertension is defined as having a blood pressure greater than 140/90 on two occasions at least 6 hours apart.

<span class="mw-page-title-main">Atosiban</span> Chemical compound

Atosiban, sold under the brand name Tractocile among others, is an inhibitor of the hormones oxytocin and vasopressin. It is used as an intravenous medication as a labour repressant (tocolytic) to halt premature labor. It was developed by Ferring Pharmaceuticals in Sweden and first reported in the literature in 1985. Originally marketed by Ferring Pharmaceuticals, it is licensed in proprietary and generic forms for the delay of imminent preterm birth in pregnant adult women.

<span class="mw-page-title-main">Placental abruption</span> Medical condition

Placental abruption is when the placenta separates early from the uterus, in other words separates before childbirth. It occurs most commonly around 25 weeks of pregnancy. Symptoms may include vaginal bleeding, lower abdominal pain, and dangerously low blood pressure. Complications for the mother can include disseminated intravascular coagulopathy and kidney failure. Complications for the baby can include fetal distress, low birthweight, preterm delivery, and stillbirth.

<span class="mw-page-title-main">Cerebral hypoxia</span> Oxygen shortage of the brain

Cerebral hypoxia is a form of hypoxia, specifically involving the brain; when the brain is completely deprived of oxygen, it is called cerebral anoxia. There are four categories of cerebral hypoxia; they are, in order of increasing severity: diffuse cerebral hypoxia (DCH), focal cerebral ischemia, cerebral infarction, and global cerebral ischemia. Prolonged hypoxia induces neuronal cell death via apoptosis, resulting in a hypoxic brain injury.

<span class="mw-page-title-main">Uterine rupture</span> Medical condition

Uterine rupture is when the muscular wall of the uterus tears during pregnancy or childbirth. Symptoms, while classically including increased pain, vaginal bleeding, or a change in contractions, are not always present. Disability or death of the mother or baby may result.

A contraction stress test (CST) is performed near the end of pregnancy to determine how well the fetus will cope with the contractions of childbirth. The aim is to induce contractions and monitor the fetus to check for heart rate abnormalities using a cardiotocograph. A CST is one type of antenatal fetal surveillance technique.

<span class="mw-page-title-main">Cervical effacement</span>

Cervical effacement or cervical ripening refers to the thinning and shortening of the cervix. This process occurs during labor to prepare the cervix for dilation to allow the fetus to pass through the vagina. While this a normal, physiological process that occurs at the later end of pregnancy, it can also be induced through medications and procedures.

<span class="mw-page-title-main">Intrauterine hypoxia</span> Medical condition when the fetus is deprived of sufficient oxygen

Intrauterine hypoxia occurs when the fetus is deprived of an adequate supply of oxygen. It may be due to a variety of reasons such as prolapse or occlusion of the umbilical cord, placental infarction, maternal diabetes and maternal smoking. Intrauterine growth restriction may cause or be the result of hypoxia. Intrauterine hypoxia can cause cellular damage that occurs within the central nervous system. This results in an increased mortality rate, including an increased risk of sudden infant death syndrome (SIDS). Oxygen deprivation in the fetus and neonate have been implicated as either a primary or as a contributing risk factor in numerous neurological and neuropsychiatric disorders such as epilepsy, attention deficit hyperactivity disorder, eating disorders and cerebral palsy.

Postterm pregnancy is when a woman has not yet delivered her baby after 42 weeks of gestation, two weeks beyond the typical 40-week duration of pregnancy. Postmature births carry risks for both the mother and the baby, including fetal malnutrition, meconium aspiration syndrome, and stillbirths. After the 42nd week of gestation, the placenta, which supplies the baby with nutrients and oxygen from the mother, starts aging and will eventually fail. Postterm pregnancy is a reason to induce labor.

<span class="mw-page-title-main">Uterine atony</span> Loss of tone in the uterine musculature

Uterine atony is the failure of the uterus to contract adequately following delivery. Contraction of the uterine muscles during labor compresses the blood vessels and slows flow, which helps prevent hemorrhage and facilitates coagulation. Therefore, a lack of uterine muscle contraction can lead to an acute hemorrhage, as the vasculature is not being sufficiently compressed. Uterine atony is the most common cause of postpartum hemorrhage, which is an emergency and potential cause of fatality. Across the globe, postpartum hemorrhage is among the top five causes of maternal death. Recognition of the warning signs of uterine atony in the setting of extensive postpartum bleeding should initiate interventions aimed at regaining stable uterine contraction.

Couvelaire uterus is a rare but not a life-threatening condition in which loosening of the placenta causes bleeding that penetrates into the uterine myometrium forcing its way into the peritoneal cavity. This condition makes the uterus very tense and rigid.

<span class="mw-page-title-main">Vaginal delivery</span> Delivery through the vagina

A vaginal delivery is the birth of offspring in mammals through the vagina. It is the most common method of childbirth worldwide. It is considered the preferred method of delivery, with lower morbidity and mortality than Caesarean sections (C-sections).

A uterotonic, also known as an oxytocic or ecbolic, is a type of medication used to induce contraction or greater tonicity of the uterus. Uterotonics are used both to induce labor and to reduce postpartum hemorrhage.

<span class="mw-page-title-main">Circumvallate placenta</span> Medical condition

Circumvallate placenta is a rare condition affecting about 1-2% of pregnancies, in which the amnion and chorion fetal membranes essentially "double back" on the fetal side around the edges of the placenta. After delivery, a circumvallate placenta has a thick ring of membranes on its fetal surface. Circumvallate placenta is a placental morphological abnormality associated with increased fetal morbidity and mortality due to the restricted availability of nutrients and oxygen to the developing fetus.

Fetal scalp blood testing is a technique used in obstetrics during active labor to confirm whether a fetus is receiving enough oxygen. This is a supplementary procedure used to determine if fetal acidemia has occurred following fetal cardiac distress. While continuous fetal heart rate monitoring is the primary method for assessing fetal wellbeing during labor, a change in fetal heart rate is not indicative of fetal acidemia. Some of the signs and symptoms of oxygen deprivation are pH in the umbilical cord, abnormal fetal heartbeat and abnormal coloration of amniotic fluid. This correlation can only be concluded by sampling fetal scalp blood and measuring acid status. Therefore, fetal scalp blood testing could be used to reduce the number of unnecessary emergency caesarean sections made on the decision of fetal heart rate alone.

<span class="mw-page-title-main">Placental expulsion</span>

Placental expulsion occurs when the placenta comes out of the birth canal after childbirth. The period from just after the baby is expelled until just after the placenta is expelled is called the third stage of labor.

<span class="mw-page-title-main">Prolonged labor</span> Medical condition

Prolonged labor is the inability of a woman to proceed with childbirth upon going into labor. Prolonged labor typically lasts over 20 hours for first time mothers, and over 14 hours for women that have already had children. Failure to progress can take place during two different phases; the latent phase and active phase of labor. The latent phase of labor can be emotionally tiring and cause fatigue, but it typically does not result in further problems. The active phase of labor, on the other hand, if prolonged, can result in long term complications.

References

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