Correct positioning of the iCup2® on the fetal head is essential to ensure the successful operation. The cup must be applied to the «flexion point». This «flexion point» is located on the sagittal suture 3 cm in front of the posterior fontanelle at thee intersection between the sincipital-chin diameter and the fetal scalp (Figures 2,3). The longer the lever (the distance between the atloid-occipital joint and the occiput) on which the instrument acts, the easier it is to flex the head, and the less traction is required to obtain this flexion (Figure 4).
In practice, the iCup2® should be positioned as nearest to the fetal occiput as possible.
If the iCup2® is placed too close the point where the fetal spine projects onto the skull, the efficacy of the device is reduced or even totally lost. An error in diagnosing the fetal position can transform the extractor into a deflexion instrument, leading to total dystocia (Figure 5).
The angle of traction depends on 2 factors:
1) The type of position of the fetal head
2) How high it is in the pelvis As a result, initially (during flexion), the traction is intended to complete the flexion of the presentation and then during the second stage (descent), it must be applied exactly in line with the natural progression of the fetal head, reproducing as far as possible the mechanics of spontaneous delivery.
The tractions should be gentle and continuous. First of all, after locating the posterior fontanelle, the cup is applied to the «flexion point». Then, depending on the type of position, there are theoretically 6 possible directions of traction:
Once maximum flexion has been obtained it is sometimes necessary to take the cup off; and reposition it nearest to the fetal occiput before starting second phase of traction.
If the flexion of the vertex is correct, there is no need for this first phase of traction. It should also be observed that in the case of an anterior position the direction of traction required to achieve flexion is the same as that used during the second stage of traction.
In case of posterior or transverse positions, it is usually possible and often sufficient to start the second stage of traction: counter-reaction of the fetal forehead pressing against the anterior arch of the pelvis is sufficient to achieve effective flexion.
The second stage of traction must reproduce, helping rather than hindering the natural progression of the vertex through the pelvis. The traction is not applied in a single direction, but in different directions depending on the progress of the vertex through the pelvis. We should remember that at all levels in the pelvis, the traction straps must always be perpendicular to the plane of the cup. A slight delay relative to the ideal direction of traction can often be helpful (always tend to pull downwards).
In the inlet pelvic strait traction is applied along the umbilico-coccygeal axis. When the traction strap of the cup comes into contact with the coccyxn this depresses the posterior perineum. To be able to work effectively, the obstetrician should sit or kneel on the floor, and pull towards his or her feet.
• Lateral swaying movements are not recommended
• The direction of traction should be raised gradually till it reaches horizontal when the cup appears at the perineum and finally, while still gradually raising the direction of traction, becomes almost vertical when the fetus is expelled
• The traction force, which is still moderate, is applied during the uterine contractions, and assisted by the mother’s abdominal pushing; between 2 uterine contractions, the obstetrician should simply hold the fetus where it had reached at the last push
• The descent of the vertex is checked by the finger of the obstetrician’s left hand, which remains inside the vagina
During expulsion, between the uterine contractions, good perineal amplitude is obtained by limited flexion-extension movements of the fetal head obtained using the iCup2®. However, doing this can exacerbate injuries of the fetal scalp.
When should one give up?
• After 10 minutes of traction
• After a period time corresponding to five uterine contractions
• After it has been dislodged twice
If the cup comes of (or «pops off»), it indicates that the cup has not been correctly positioned, the direction of traction is incorrect, cephalopelvic disproportion or defective vacuum, never happens suddenly, but is preceded by popping sounds of leakage before the cup comes off. If this happens, after checking the type of position (this can be checked using ultrasound in the labor room) and the level of the presentation in pelvic tract, changing the direction of traction can be effective. If the leakage continue, check the parameters of the pump. If the fetal head does not progress, this approach should be abandoned, and a C section carried out without delay.
• If lesions are produced on the fetal scalp
NOTE: the cardiotocographic recording must also be monitored constantly. Any exacerbation of the recording must lead to the desertion of the attempt to extract the fetus via the birth canal unless one is sure that it can be done quickly.
Factors for a lack of success of the method
• Deflexion or excessive asynclitism of the fetal head,
• Retraction of the cervix or incomplete dilatation of the cervix,
• Defective equipment or the lack of appropriate equipment,
• Dislodgement of the cup during traction along the wrong axis or while the mother is not pushing,
• Incorrect positioning of the cup. The obstetrical cup must be positioned nearest to the fetal occiput in order to promote flexion of the head. Any error in applying the cup leads to dystocia and increases the risks of fetal trauma,
• Lack of maternal cooperation,
• Fetopelvic disproportion.
If the use of the cup is expected to be difficult, it must be done in the cesarean theater or near to it, and in the presence of an anesthetist and a pediatrician.
The obstetrical cup is applied to the fetal skull, and does not make it any bigger. The obstetrical cup avoids the problem inherent in general anesthesia. Most studies have found that the cup produces less harmful effects on the soft tissues of the woman than the use of forceps. The only lesions observed are those resulting from inadequate monitoring of disengagement, or failing to check that the device has been installed properly.
Rare maternal damage :
Complete or complicated perineal tearing
The cup does not constitute a risk factor for these lesions in contrast to forceps. Promoting factors include a fetal weight in excess of 4 kg, primiparity, and occipito-sacral disengagement.
Extensions of vaginal tears to the uterine cervix are very rare.
Blood loss is often related to iatrogenic or traumatic perineal lesions.
Damage of the vaginal mucosa if a fold remains trapped between the cup and the presentation.
Cervical damage (if the cup has been positioned before complete cervical dilatation has occurred) which involves the same mechanism.
Incidents of this type can easily be avoided by carefully checking the position of the cup when it is inserted.
• Annular detachment of the cervix
• Bladder-vagina or bladder-uterine fistula
Remote damage: anal and/or urinary incontinence
Damage of the pudendal nerve seems to be responsible for disorders affecting pelvic statics. Instrumental extractions are a promoting factor, especially forceps deliveries.
Few statistical studies have demonstrated isolated responsibility of vacuum assisted delivery cup in neonatal accidents, particularly in a context of concomitant fetal distress. The most serious and unusual complications can occur after the prolonged and difficult use of vacuum cups during which maximum traction forces may have been applied to the scalp.
The praiseworthy intention of seeking to reduce the number of C-sections obviously does not justify running any neonatal risk in borderline indications for the vacuum cup. The forces applied by the cup to the fetal scalp can lead to secondary injuries. Four types of force are applied to the fetal skull: negative suction pressure, traction force, a circular force in the context of rotation, and shear forces. The combination of these phenomena explain the various different lesions observed and reported on the neonate.
Damage of the fetal scalp
This is fairly common and banal, it can correspond to a simple «bun» corresponding to the concavity of the vacuum cup, which disappears within a few hours (12 to 18 hours), or alternatively can be a visible and palpable hematoma bounded by a major supporting cellulo-adipose tissue. In large examples, 20 to 40 ml of blood may collect, which results in anemia and accentuation of the physiological jaundice due to an excess of unconjugated bilirubin that has to be resorbed. A puncture should not be carried out.
Excoriation of the scalp
Abrasion and laceration of the skin occur when the cup pops off or slips. These skin lesions can provide an entry point for infection, but the outcome is usually benign. Local antiseptic treatment and sterile fields are called for. Serious lesions are rare, and often secondary to the causes of failure of the cup discussed above. In exceptional cases, local alopecia has been observed subsequently.
Local detachment of the skin
This involves a caput succedaneum plus detachment of the skin extending over several cm2 where the skin is limp and fluctuating. Within a few days, this will become taut again and spontaneously adhere to the scalp.
Cephalohematoma or sub-periosteal hematoma
This is the collection of blood between the bone and the periosteum and although it does occur during spontaneous childbirth, it happens more often during vacuumassisted deliveries. Asynclitism is a promoting factor. Unlike caput succedaneum, it does not extend over the sutures, and is often parietally located, where it forms a fluctuating swelling clearly outlined by a palpable ridge corresponding to periosteal detachment. It is secondary to a rupture of the diploic veins. It currently develops on Day 2 or 3 of life. It is very slowly resorbed, and this occurs at the cost of ossification over several weeks. It is sometimes associated with fracture of the skull and if there is any doubt, an X-ray could be useful. Like caput succedaneum, it can result in moderate anemia and resorption jaundice. No attempt should be made to puncture it.
Diffuse, subcutaneous hematoma of the scalp
Diffuse, subcutaneous hematomas of the scalp are promoted by fetal distress, infection, coagulation disorders, a persistent occipito-posterior position and a difficult vacuum-assisted delivery. Their rarity (<2°/°° per births) should not lead us to forget that they can be extremely serious. This condition involves bleeding from damage of Santorini’s emissary veins that develops insidiously and continuously, since it is not restricted by any anatomic structure: the blood spreads between the epicranial aponeurosis and the periosteum in a slack cellular space, without any supporting tissue, and this can contain up to 260 mL of blood in a neonate. The entire scalp becomes detached, masking the bone sutures. The clinical signs may become apparent from a few hours to several days after birth.
Sub-dural, extra-dural, intra-parenchymatous or intra-ventricular bleeding does not seem to be directly linked to vacuum-assisted childbirth, but can be secondary to prolonged cerebral anoxia in the context of acute fetal distress or of a congenital clotting disorder. Retinal hemorrhage
has been more frequent with obstetrical vacuum cups. They have usually been correlated with the duration of labor. They are resorbed spontaneously, and no sequelae have been reported in the literature.
Fractures of the skull
The iCup2® does not seem to be particularly likely to produce a fracture of the bones of the skull, because unlike older vacuum pumps it does not result in a risk of a depressed fracture of the skull if the cup pops off.
Jaundice has been reported in a context of vacuum-assisted extraction, requiring more phototherapy Infections. It does not look as though any infective role can be attributed to vacuum cups.
Lesions affecting the brachial plexus are not specific to the use of vacuum cups; but are linked to dystocia of the shoulders. Nevertheless, be carefull in case if the foetus is suspected of having macrosomy.
No publications have reported any differences between spontaneous deliveries and those carried out using forceps or vacuum cups. Cups and forceps do not increase the long-term morbidity and do not influence intelligence when the neonate reaches adulthood
|CONVERSION TABLE OF PRESSURE MEASUREMENTS|
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|* 1st and 2nd levels|
Do not use the device it its package has been opened or damaged, or if its shows any defect due to transport, or bad conditions of storage, or a bad handling, which could be harmful to its useWe remind you that this device is strictly disposable which can not be reuses in case of reuse, this performance could be affected with an important risk of contamination
Mentions Single patient use. Sterile unless unit container is opened or damaged. Destroy after single patient use. Do not re-sterilise.