A multiparous woman at 40 weeks in active labour has been in the second stage for 90 minutes with no progress. The fetal head is at +2 station, OA position, no caput or moulding. CTG is reassuring. The obstetrician elects ventouse (vacuum) delivery. The cup is placed 3 cm anterior to the posterior fontanelle (flexion point). After 3 consecutive pulls without descent, the procedure is abandoned. This is called a:
- A Failed forceps
- B Failed ventouse — three pop-offs rule ✓
- C Trial of instrumental delivery
- D Abandoned operative delivery due to operator fatigue
Correct answer: B. Failed ventouse — three pop-offs rule
Explanation
The 'three pop-offs rule' is a safety criterion for ventouse delivery: if the cup detaches (pop-off) three times despite correct technique and placement, the procedure should be abandoned. Similarly, failure of progressive descent after three pulls also mandates abandonment. This prevents excessive traction force and fetal trauma. In this case, three pulls without descent (not three pop-offs) indicate a failed ventouse; proceeding to caesarean is appropriate. 'Trial of instrumental delivery' is planned in theatre, not this scenario.
Reference: Williams Obstetrics, 26th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.