Introduction

Induction of labor (IOL) in women with unfavorable cervical conditions is not an easy process and remains one of the challenges in obstetrics. In those conditions, the use of medications such as prostaglandin PG might be involved in spite of potential inconvenient side effects, high failure rates, and with Caesarean section deliveries. Multiple clinical studies have shown the adventages of mechanical methods for IOL when cervical conditions are unfavorble compared to the use of pharmaceutical agents.

Components of the different types of PICD

The Pre-Induction Cervical Dilators (PICD) are double balloon catheters that function as mechanical devices in order to facilitate the IOL process when the cervical conditions are unfavorable. There are three types of PICDs, each of which is based on the double balloon catheter construction.

• Type1 PICD

Does not offer the optional use of intra-cervical PG medications. It does not have an injection valve or an opening outlet to the cervical canal.

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• Type2 PICD

Provides a concomitant treatment option with its optional intra-cervical application of PG gel preparations in an opening located between the two balloons (the uterine and the vaginal) and corresponding to the cervical canal.

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• Type3 PICD

Has a concomitant extra-amniotic instillation option.
It has multiple openings located at the end of the catheter's long tip, corresponding to the
extra-amniotic space. Continuous administration of normal saline solution (for IOL) can be performed through a corresponding valve. Continuous extra-amniotic administration of diluted prostaglandin solutions such as PGE2 or PGF2 alpha are optional concomitant methods in patients with intra-uterine fetal demise or other indications necessitating late termination.

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Mechanism of action of the varous types of PICD

• Gradual dilatation of the cervix by the pressure applied by the inflated
   balloons, which are located on both openings of the cervix.
• Release of endogenous prostaglandin from the decidua adjacent to the
   inflated uterine balloon.
• Concomitant effect of the PG gel if applied to the cervical canal
   (Type 2 PICD) or by the effect of continuous extra-amniotic instillation
   (Type 3 PICD).

Insertion Technique:

• Inserting the device and inflating the uterine balloon.
• Inflating the vaginal balloon and removing the speculum.
• Additional inflation of the balloons until each balloon contains 80ml of
  fluid. At that point, the end of the device is being taped to the patient's
  thigh.
• Applying intra-cervical PG gel (type 2 PICD).
• Administering normal saline continuously (type 3 PICD).

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Removal of the device

This is performed by the deflation of the both balloons through the corresponding valves marked U and V. Our policy is to introduce the device late in the afternoon or evening according to patient and doctor's convenience and the device is removed the following morning. After removal of the device a cervical dilatation of 3 cm or more is usually detected.

Further labor management

Labor can be induced by artificial rupture of the membranes and by administration of intravenous oxytocin. If the membranes rupture spontaneously before removing the device, deflate the balloons and remove the device since contractions signaling active labor usually develop.

Spontaneous expulsion of the device

Spontaneous expulsion might occur if uterine contractions are regular, active labor has begun, and with cervical dilatation greater than 5 cm. After spontaneous expulsion of the device it is recommended to assess the cervical dilatation and the stage of labor.

Advantages

The PICDs offers the following advantages:
• Ripens and dilates the cervix by a mechanical device for better, more
  comfortable results.
• Eliminates the side effects of repeat medications.
• Affords excellent results with minimal discomfort.
• Adapts to contour of the cervical canal for easy insertion.
• Suits patients where prolonged uterine contractions are preferably
  avoided (IUGR, postdates) as well as those who have delivered
  previously by Caesarean section.
• Gives patients the ability to move and walk around while the device in
  place and is ideal for planned overnight cervical dilation and next day
  delivery.
• Is a cost-effective method with high success rates that have been
  documented by clinical trials.

Type1 PICD has been approved for the U.S. market (K040625).
Types 2 and 3 PICDs have been appoved by the CE and by the TGA (Australia).