A G2P1 woman at 41+2 weeks with a Bishop score of 3 requires cervical ripening and induction. A transcervical Foley catheter is placed. What is the mechanism by which mechanical cervical ripening causes cervical effacement and dilation?
- A Stretching the lower uterine segment releases oxytocin from the posterior pituitary
- B Balloon pressure compresses cervical collagen fibres, directly causing mechanical effacement
- C Foley catheter acts as a foreign body inducing cytokine-mediated myometrial contractions
- D Direct pressure stimulates local prostaglandin release from decidua and cervical stroma, initiating cervical ripening ✓
Explanation
Mechanical cervical ripening with a transcervical Foley catheter works primarily through local prostaglandin production — the pressure of the balloon on the lower uterine segment and cervix stimulates the release of prostaglandins (particularly PGE2 and PGF2α) from the cervical stroma, decidua, and membranes. These prostaglandins promote collagen remodelling, increase hyaluronic acid content, activate matrix metalloproteinases (MMPs), and inhibit progesterone receptors in the cervix, collectively causing cervical softening, effacement, and dilation. The effect is not purely mechanical collagen compression.
Reference: Williams Obstetrics, 26th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.