Prolonged labor is a pathologically delayed labor activity with a total duration of more than 18 hours. The reasons are overwork and insufficient preparation of a woman for childbirth, pregnancy complications, gynecological and extragenital diseases. Prolonged labor is characterized by weak and ineffective contractions, slow opening of the uterine pharynx, prolonged standing of the fetal head in one position. Partogram and cardiotocography data are sufficient to confirm the diagnosis. The tactics of management of women in labor involves medical stimulation of the uterus or cesarean section for emergency delivery.
O63 Prolonged labor
Prolonged labor accounts for up to 80% of all abnormal labor and occurs in 10-12% of women in labor. These include any variants of childbirth that proceed slower than physiological ones, regardless of the cause of the problem. For primiparous women, the boundary time interval of norm and pathology is considered to be 18 hours, and for repeat births this figure is 12-13 hours. If there is no opening of the cervix for more than 4 hours or the fetus progresses through the birth canal for more than 2 hours, obstructive labor is diagnosed.
The main factor of prolonged labor is recognized as the weakness of labor activity, which occurs primarily (insufficiently active contractions from the very beginning) or secondarily (a sharp weakening of normal uterine contractions). More rare causes include hypertensive dysfunction and discoordination of labor activity. In the painful period, pathology is observed when the fetus does not match the size of the pelvis (cephalopelvio-disproportion).
Specialists in the field of obstetrics and gynecology identify many endogenous and exogenous factors that provoke prolonged labor. Unmodified factors include a burdened obstetric history in the mother and closest relatives, the age of the first-time mother up to 18 years or older than 35 years, a long interval between pregnancies. Other reasons for slowing down labor activity:
- Anatomical narrowing of the pelvis. Pathology is observed on average in 3% of pregnant women. The most common is a transversely narrowed pelvis (45.2% of cases), less often a simple flat (13.6%), evenly narrowed (8.5%) and planarachytic (6.5%) are diagnosed. Oblique pelvis occurs in women who have suffered fractures of the pelvic bones with displacement, having exostoses and bone tumors.
- Incorrect insertion of the head. The slowing down of the second period of labor is typical for incorrect insertion of the fetal head: high straight and low transverse standing of the swept seam, extensor presentation, asynclitic insertion of the head.
- Endocrine diseases. Obesity is recognized as the most common risk factor, with severe form of which in 33% of cases, weakness of uterine muscle contractions is observed. Prolonged labor develops in 20% of women with hyperandrogenism. Possible risk factors include metabolic syndrome, thyroid pathology.
- Somatic diseases. Iron deficiency anemia has the greatest effect on the contractile activity of the myometrium. This is due to impaired myoglobin synthesis and hemic tissue hypoxia. An important predisposing factor is called chronic infections of the genitourinary tract – they increase the risk of prolonged labor by 2.6-7 times.
Physiological childbirth consists of 3 stages: opening of the cervix, expulsion (attempts), birth of the afterbirth. The period of opening of the cervical canal is divided into a latent and active phase, lasts 10-12 hours in primiparous women, 6-8 hours in repeat-bearing women. The expulsion of the fetus lasts 1-2 hours and 20-60 minutes, respectively. The duration of the third period is no more than half an hour, regardless of the number of births in the anamnesis.
Biochemical disorders play a significant role in the pathogenesis of prolonged labor. In the body of a woman in labor, the level of estrogens decreases, there is a low activity of enzymes of the pentose phosphate cycle, the balance of carbohydrate, protein and mineral metabolism is disturbed. The main morphological substrate of prolonged labor is a low level of contractile proteins in the cytoplasm of uterine myocytes.
At the same time, there is a disorganization of the conducting system and a displacement of the “rhythm driver”, which is why contractions become uncoordinated and sharply painful. Disorders of muscle contractility are accompanied by hypoxic changes, accumulation of under-oxidized products and activation of anaerobic glycolysis. Beta-adrenergic receptors, which are sensitive to oxytocin stimulation, are destroyed in the uterus, so childbirth is delayed.
The oppression of labor activity is indicated by weak, rare and short contractions. This type of uterine contractions occurs from the very beginning of labor or appears in their process, replacing normal labor activity. Prolonged and inconclusive contractions greatly tire a woman, are accompanied by severe pain, cause negative psychoemotional reactions.
Palpation determines a decrease in the tone and excitability of the uterus, possibly uneven tension of its individual segments. The adjacent part of the fetus is in the same plane for a long time. A vaginal examination reveals a delayed opening of the cervical canal. Against the background of prolonged labor, the process of urination is often disrupted, although there are no signs of compression of the bladder.
Irregular and prolonged muscle contractions cause disorders of uteroplacental blood flow and fetal hypoxia. In the absence of an emergency delivery, a child may experience hypoxic-ischemic encephalopathy, asphyxia, neonatal hypoglycemia. When fetuses are extracted using obstetric instruments, there is a risk of cerebral hemorrhage, Duchene-Erb and Dejerin-Klumpke paralysis, fracture of the collarbone, humerus or femur.
Prolonged labor dramatically increases the risk of complications in the mother. Decreased tone and overstretching of the uterus are fraught with problems with the birth of the afterbirth in the third period, prolonged hypotonic bleeding. With a prolonged anhydrous period or invasive manipulations, postpartum endometritis, peritonitis, obstetric sepsis may develop.
Complications may occur after stimulation, which is traditionally used to accelerate prolonged labor. Inadequate uterine contractions in strength and frequency are fraught with premature placental abruption, rupture of the uterus and birth canal, profuse bleeding. Critical disruption of blood flow in the uterus causes severe hypoxia and intranatal fetal death.
The examination of a woman is carried out by an obstetrician-gynecologist directly in the prenatal ward or in the delivery room. Prolonged labor is a clinical diagnosis that is established with constant monitoring of the course of labor and fixing its key indicators on the partogram. To study the nature of the course of labor, the following diagnostic methods are used:
- Obstetric research. Prolonged labor is indicated by the duration of the latent phase of the first period of more than 8 hours, the opening of the uterine pharynx less than 2 cm during 4 hours of the active phase, the absence of lowering of the fetal head or its pronounced configuration.
- Cardiotocography. Continuous recording of fetal heartbeat and uterine tone allows you to monitor the condition of the child, detect signs of intranatal hypoxia and other life-threatening conditions in time. A terrible signal is a decrease in the basal fetal heart rate of less than 110 per minute, multiple decelerations.
To choose an adequate method of delivery, differentiation of the causes of prolonged labor is carried out. Weak labor activity, which requires hormonal or prostaglandin stimulation, should be distinguished from discoordination, in which such therapy is contraindicated. With a prolonged course of the second period, differential diagnosis with an anatomically and clinically narrow pelvis is shown.
Tactics of conducting protracted labor
To stimulate labor activity in the first period, amniotomy with the introduction of oxytocin, prostaglandins is indicated. They stimulate uterine contractions and accelerate the course of labor. The drugs are administered intravenously drip under the control of cardiotocography. The rate of administration varies from 6-8 to 40 drops of solution per minute. In the second period, when the amniotic fluid is poured out, it is also possible to administer oxytocin under strict control of the fetal heartbeat.
The criterion for effective stimulation of labor is adequate labor activity: 4-5 uterine contractions of average intensity for 10 minutes. At the same time , contractions should be regular and last about 40-50 seconds . After 2 hours from the start of the drug administration, the rate of cervical dilation should be 0.5-1 cm per hour. In the second period, doctors try to achieve the advancement of the head along the genital tract within 1 hour after the start of the infusion.
With the ineffectiveness of hormonal stimulation, symptoms of fetal hypoxia and deterioration of the condition, women take measures to complete prolonged labor as soon as possible. If the woman in labor is in the first period, delivery is carried out by emergency Caesarean section. When the head is located in the pelvic cavity, the child is removed by vacuum extraction or the application of obstetric forceps.
Prognosis and prevention
Most protracted labor ends with a successful delivery and the birth of a live fetus. However, this does not exclude postpartum complications in the mother and long-term negative consequences for the baby. To prevent abnormal labor, it is necessary to properly manage pregnancy, psychological preparation for childbirth, and create a comfortable environment for a woman in labor: the possibility of active behavior, rest, eating and drinking water at will.