Fetal vacuum extraction

Extraction of the fetus by the head using a special vacuum device is called vacuum extraction. The operation of vacuum extraction of the fetus is a labor-releasing operation.

As is known, the most common cause of perinatal morbidity and mortality is fetal oxygen deficiency during labor and birth trauma. According to extensive statistics, fetal oxygen starvation and craniocerebral trauma account for 50-70% of all mortality in children under one year of age.

The risk of developing traumatic brain injury due to intranatal fetal hypoxia is especially increased in cases where obstetric operations are required to deliver the baby, since “instrumental” asphyxia is superimposed on “pre-instrumental” asphyxia.

Vacuum extraction of the fetus is one of the most common obstetric surgeries in Ukraine. The vacuum extractor is used on average in 1.3-3.6% of all births in maternity hospitals in the country. However, despite the widespread use of the vacuum extractor in continental Europe and Scandinavian countries, it should be noted that in most English-speaking countries it remains an unpopular operation. In the United States, there is an extremely reserved attitude towards the operation of vacuum extraction of the fetus compared to obstetric forceps. This advantage was further strengthened in favor of obstetric forceps after reports of severe fetal trauma caused by the operation of vacuum extraction of the fetus appeared in the literature.

American obstetricians very rarely use the operation of vacuum extraction of the fetus. This is apparently due to a number of reasons. Firstly, the national preference for obstetric forceps in the United States depends on the principles taught in obstetrics. Secondly, some obstetricians, including domestic ones, overestimated the importance of this operation and began to use it for expanded indications, which was not always justified and in some cases led to unfavorable results that were revealed during a comprehensive examination of newborns and during an analysis of remote results. Therefore, the positive reviews of many obstetricians who first used this operation were replaced by a more restrained assessment of it and even to a certain extent a negative attitude towards it from some specialists due to the increase in the number of children with damage to the central nervous system after operative delivery by this method.

However, to this day there is no unified assessment of the use of this operation, and the immediate and remote consequences of the physical and neuropsychic development of the newborn child have not been studied in detail. This is all the more important because in some obstetric situations (if there is a need for urgent delivery, when the moment for a cesarean section has been missed or there are contraindications for it, and the head is inaccessible for the application of obstetric forceps due to its high position) vacuum extraction of the fetus is the only possible operation for the birth of a living child. Some authors in monographs devoted to craniotomy in modern obstetrics believe that the latter can be considered indicated if there is an immediate threat to the life of the mother in the presence of contraindications to a cesarean section or other surgical interventions (application of obstetric forceps, classic rotation, etc.).

Therefore, the obstetrician must, in a specific situation, choose the most gentle method of delivery for both the mother and the fetus.

In recent years, the method of craniocerebral hypothermia of the fetus has been successfully used to treat intranatal fetal hypoxia, especially in cases of uteroplacental or fetoplacental blood flow disorders, when methods of treating fetal hypoxia by influencing the fetus through the mother's body are often ineffective. This method allows for direct influence on the fetus in order to increase the brain's resistance to oxygen starvation and prevent pathological consequences of oxygen deficiency. However, the available literature does not contain any works devoted to craniocerebral hypothermia of the fetus in surgical obstetrics. For this purpose, the Vacuum-Hypotherm-Extractor device was developed and created, as well as the technique of vacuum-hypotherm-extraction of the fetus. The device allows for simultaneous craniocerebral hypothermia of the fetus and obstetric operations, in particular, vacuum extraction of the fetus.

The use of simultaneous fetal hypothermia during vacuum extraction allows to reduce the intensity of oxidative and enzymatic processes, slow down the development of acidosis, minimize the so-called "biochemical" injury associated with it, reduce the blood flow rate and volumetric blood flow, improve microcirculation and prevent the development of post-hypoxic cerebral edema. Keeping the fetus under the protection of hypothermia makes it possible to extend the time interval for performing vacuum extraction of the fetus, to carry out less forced tractions compared to conventional vacuum extraction of the fetus. The new surgical technique allows for the most careful delivery, minimizing the possibility of both biochemical and mechanical craniocerebral injury of the fetus. Noting the advisability of using the developed vacuum-hypotherm extractor in obstetric practice, Academician M.S. Malinovsky wrote that “simultaneous craniocerebral hypothermia is very important for increasing the resistance of brain tissue to oxygen deficiency and preventing the occurrence of injuries during vacuum extraction.”

When determining the location of the fetal vacuum extraction operation in modern obstetrics, the number of pathological conditions in pregnant women and women in labor has not decreased and the frequency of surgical methods of delivery has not decreased. Only the proportion of individual pathological conditions has changed, which to one degree or another can complicate the course of pregnancy and childbirth. In addition, a significant expansion of indications for the use of a vacuum extractor in individual maternity institutions (up to 6-10% in relation to all births) has not reduced perinatal mortality and pathology in them. The possibilities of using a vacuum extractor, which is used in maternity hospitals in Ukraine in 15-35 cases per 1000 births, were soberly assessed.

Vacuum extraction of the fetus does not replace obstetric forceps, it is an independent operation, the use of which has its own indications, conditions and consequences. This operation is theoretically justified and, if carried out correctly, does not increase the trauma to the fetus in comparison with other obstetric operations that extract the fetus through the birth canal. At the same time, it should be noted that at present there is no preferential trend towards the operation of applying forceps in comparison with the operation of vacuum extraction of the fetus.

Indications for vacuum extraction of the fetus

On the mother's side - complications of pregnancy, childbirth or somatic pathology that require shortening the second stage of labor:

• weakness of labor activity in the second stage of labor;
• infectious and septic diseases with a deterioration in the general condition of the woman, high body temperature.

From the fetus: progressive acute hypoxia (distress) of the fetus in the second stage of labor when it is impossible to perform a cesarean section.

Conditions for performing vacuum extraction of the fetus

1. Living fruit.
2. Complete opening of the cervix.
3. Absence of amniotic sac.
4. Correspondence between the sizes of the fetal head and the mother's pelvis.
5. The fetal head should be located in the pelvic cavity or in the plane of the pelvic outlet in the occipital presentation.

To perform the operation of vacuum extraction of the fetus, the active participation of the woman in labor is necessary, since the pushing is not turned off during the operation. The presence of diseases in the mother that require turning off pushing is a contraindication to this method of extracting the fetus. The operation is performed under local anesthesia (pudendal anesthesia). If the birth is carried out under epidural anesthesia, then vacuum extraction is also performed under this type of anesthesia.

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Vacuum extractor models

The vacuum extractor consists of a cup, a flexible hose and a special device that provides negative pressure under the cup, not exceeding 0.7-0.8 kg/cm2 ^. Vacuum extractor cups can be metal (Maltstrom vacuum extractor), more modern models have plastic rigid (polyethylene) or stretchable (silicone) disposable cups. In the Maelstrom cup, the vacuum tube and chain are in the center. Modified cups have been created (GC Bird): "front" - the chain is in the center, and the vacuum tube is eccentric; "back" - the chain is in the center, and the tube is on the side. These cups are selected depending on the position of the head. Currently, disposable silicone cups are mainly used.

Technique of vacuum extraction of the fetus

The following points are highlighted during the operation:

• insertion of the vacuum extractor cup;
• creating a vacuum using a special device;
• traction on the fetal head;
• removing the cup.

Inserting the vacuum extractor cup into the vagina is not difficult. With the left hand, spread the genital slit, and with the right, supporting the cup in a vertical-lateral position, insert it into the vagina and bring it to the head.

The inserted cup "sticks" to the head, after which it should be correctly positioned by moving it along the head. The cup should be located closer to the leading point on the fetal head, but not on the fontanelles. If the cup is located 1-2 cm in front of the posterior fontanelle, the head bends during traction, which facilitates the implementation of the flexion moment of the labor biomechanism in occipital presentation. If the cup is attached closer to the anterior fontanelle, the head unbends during traction. A significant displacement of the cup to the side of the sagittal suture during traction facilitates asynclitic insertion of the head.

After the cup is placed, negative pressure is created underneath it using a special device. Care should be taken to ensure that the soft tissues of the woman's birth canal (cervix, vagina) do not get under the cup.

For successful performance of the vacuum extraction operation of the fetus it is very important to choose the direction of tractions to ensure the advancement of the head according to the biomechanism of labor, when the conductive point of the head moves along the conductive axis of the pelvis. Tractions should be perpendicular to the plane of the cup. Otherwise, distortion and separation of the cup from the head of the fetus are possible.

The direction of traction corresponds to the rules described above for obstetric forceps. When the head is positioned in the plane of entry into the small gas, the tractions should be directed downwards (with this position of the head, it is more rational to perform a cesarean section); in case of displacement of the head into the cavity of the small pelvis, the direction of traction changes to horizontal (towards oneself); during the eruption of the head, when the suboccipital fossa approaches the symphysis, the tractions are directed upwards. The number of tractions when applying a vacuum extractor should not exceed four.

Tractions are performed synchronously with pushing. If the cup slips off the head, it cannot be moved more than twice, as this is a major trauma for the fetus. Sometimes, after an unsuccessful attempt at vacuum extraction of the fetus, conditions arise for performing an operation to apply obstetric forceps.

When applying a vacuum extractor, an episiotomy is indicated. After the fetal head has been completely extracted, the vacuum extractor cup is removed, reducing the negative pressure underneath it.

Contraindications to vacuum extraction of the fetus

• Discrepancy between the sizes of the fetal head and the mother's pelvis, in particular: hydrocephalus; anatomically or clinically narrow pelvis.
• Stillbirth.
• 3 Facial or frontal insertion of the fetal head.
• High, straight standing head.
• Breech presentation of the fetus.
• Incomplete opening of the cervix.
• Premature fetus (up to 30 weeks).
• Obstetric or extragenital pathology, which requires the exclusion of the second stage of labor.

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Complications of vacuum extraction of the fetus

Complications of vacuum extraction for the mother may include ruptures of the vagina, perineum, labia majora and minora, and the clitoral area. Complications for the fetus include: damage to the soft tissues of the head, cephalhematomas, and hemorrhages. When using soft cups of the vacuum extractor, the incidence of soft tissue damage is less common.

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