Arrest of Dilation - All You Need to Know

Introduction:

The arrest of dilation is an abnormality that occurs during pregnancy. Normal labor is progressive dilation and effacement of the cervix due to uterine contractions. Several milestones have been defined to identify normal labor. The failure to meet these milestones suggests an increased risk and is categorized as abnormal labor. The arrest of dilation may be the slowing of labor below an expected rate or maybe a complete arrest in which no progress is made for at least two hours.

What Is Normal Labor?

Normal labor is the painful and regular uterine contractions that result in delivering the fetus and placenta. Labor is predominately divided into three stages.

1. First Stage: Zero to ten centimeters.

• Latent phase.

• Active phase.

2. Second Stage: Involves the delivery of the fetus. It is again of 2 phases:

• Latent, which includes the completion of cervical dilation to the start of expulsive efforts by the mother.

• The active phase includes the onset of expulsive efforts to deliver the fetus.

3. Third Stage: It is the expulsion of the placenta.

What Is Abnormal Labor?

Abnormal labor can occur in the first, second, or third stages of labor. Abnormal delivery can occur in the first stage, where the cervix should, in normal cases, start to dilate till the completion of the same. Or in the second stage, which should result in the delivery of the baby, it can also be in the third stage, where the placenta is to be delivered.

• First and second-stage abnormalities are called protraction disorders which means that the delivery is progressing at a slower rate than what is considered normal. It can also be an arrest disorder which is a complete cessation in progress.

• Abnormal third-stage labor is the retention of the placenta beyond 30 minutes. This is considered abnormal, as the third stage should be concluded within ten to twenty minutes of delivery.

What Is Arrest of Dilation?

Friedman curve was designed to identify women at risk of dangerous vaginal delivery. According to this scale, during active labor, the cervix should progressively dilate at a rate that is not less than 1.2 cm per hour to 1.4 cm per hour for first-time labor and subsequent labor, respectively. If the delivery is not progressing at this rate, it is called the arrest of dilation or arrest of labor.

What Are the Causes of Abnormal Labor?

For the uncomplicated progression of labor, it requires certain characteristics, such as:

• Power from uterine contractions.

• Adequate pelvis for the mother to facilitate passage.

• A favorable fetal position that enables movement or passage.

Abnormal labor can be caused due to problems in any of these stages.

The size of the fetus and the capacity of the maternal pelvis are measured during propulsion from the uterus. If there is a deficiency in uterine contractions, it can be overcome by the administration of oxytocin. However, if labor abnormalities arise due to the pelvic fetal mismatch, it can lead to cesarean delivery. Maternal obesity is correlated with a more prolonged first stage of labor. In the third stage, postpartum hemorrhage (blood loss after delivery) can also be a risk. Again, this may require blood transfusions or even maternal death.

What Are the Causes for Arrest of Labor?

There are mainly two causes for the arrest of labor:

1. Inadequate Contractions:

If the contractions are not as frequent as required (more than four-minute intervals) or they do not last long enough (less than 30 seconds). In most cases, both these conditions are observed.

2. Mechanical Obstruction of Labor:

Mechanical impediments include,

• The maternal pelvis is not large enough for the baby to pass through the canal; it is called absolute fetopelvic disproportion.

• Relative fetopelvic proportion means the presence of a snug fit, but if enough time and adequate contractions are present, the fetus can pass through the birth canal.

• Fetal malposition is when the fetal head is not in a favorable position, such as the hand preceding the head or if the fetus is in a transverse position.

• If the head is slightly positioned to one side, also there may be difficulty passing through the canal, called asynclitism.

What Are the Symptoms of Arrested Dilation?

• Labor may extend for more than 14 to 20 hours.

• Dehydration, along with maternal exhaustion and drying of the mouth.

• Decrease in labor pains.

• Increased pulse rate.

• Fetal distress may develop.

• Abnormal contractions.

What Is to Be Monitored?

In order to identify abnormal labor, certain symptoms are reviewed, such as:

• Leakage of fluid or loss of mucus plug.

• Any history of vaginal bleeding may indicate placental abruption.

• The gestational age should be determined properly.

• The abdominal examination helps to determine the fetal weight and position of the fetus and whether it is in a favorable position for the descent.

• Fetal heart rate should be continuously monitored to determine the status of the baby.

• A manual vaginal examination can help evaluate maternal pelvis capacity, the degree of cervical dilation, and the relationship between the pelvis and the fetus.

What Is the Management for Abnormal Labor?

The management is based on the stage in which abnormality occurs.

A. First Stage:

1. Latent Phase:

• This stage can be prolonged for hours or even days. The decision to admit the patient should be based on the following:

• Status of the cervix.

• The psychological state of a patient.

• Any pre-existing complications.

• Tolerance to pain.

• Distance to hospital.

• If the patient is well rested, oxytocin may be administered.

2. Active Phase:

For women who are in the active stage with cervical dilation of less than 1cm, oxytocin may be administered, followed by an amniotomy. Amniotomy is the intentional breaking of an amniotic sac by the doctor. This is delayed for four to six hours in cases where the position of the fetus is high in relation to the cervix.

• If there is no change in the cervix or contractions even after four hours, it is advisable to perform cesarean delivery.

• But if labor is progressing slowly but normally, oxytocin may be continued, provided the patient does not have a history of cesarean delivery.

B. Second Stage:

• Oxytocin is administered if no changes are observed even after 60 to 90 minutes of pushing.

• If the fetus moves or rotates to a favorable position for vaginal delivery and the fetal heart rate is maintained, then operative intervention should be delayed.

• If the fetal heart rate is weak, a cesarean section is performed irrespective of the progression of the labor.

C. Arrested Dilation:

Inadequate contractions can be managed by administering oxytocin which stimulates the uterus. It is slowly administered until the desired effect is achieved; it is then lowered or stopped depending on the frequency of contractions.

The management can be summarized as follows:

• Administration of oxytocin.

• Amniotomy (intentional rupture of the amniotic sac).

• Vacuum or forceps delivery.

• Cesarean section. If one management is failing, the next step is executed.

What Are the Complications of the Arrest of Dilation?

The risks of arrested or even prolonged labor affect both the mother and the baby.

Prolonged labor can give rise to the following complications:

• Sphincter injury.

• Operative vaginal delivery.

• Perineal lacerations.

• Cesarean delivery.

• Urinary retention.

• Chorioamnionitis (infection of chorion and amnion).

• Endometritis (inflammation of the uterine lining).

• Postpartum hemorrhage (bleeding after delivery).

Danger to Fetus:

• Sepsis.

• Fetal distress due to lack of oxygen.

• Intracranial hemorrhage.

• Need for forceps or vacuum delivery.

• Long-term complications such as seizures and cerebral palsy.

Danger to the Mother:

• Cervical tears, vaginal tears.

• Intrauterine infections.

• Postpartum infection.

Conclusion

Normal delivery should typically result in the delivery of the fetus. However, numerous complications and risk factors may cause abnormalities during delivery. Physicians and nurses should be aware of the signs of abnormal labor to identify them on time. Proper monitoring and education of the nurses and doctors are necessary to prevent such complications and treat them promptly. The timely management of such complications can reduce fetal and maternal mortalities and morbidities.