Influence of the disengagement of the forceps on levator ani muscle injuries in instrumental delivery: A multicenter study

Which type of forceps is better for nonrotational operative births? A simulation study comparing Thierry spatulas and Simpson-Braun and Kielland forceps

OBJECTIVE

Obstetric forceps play an important role in safe childbirth, yet there is a lack of distinction between various forceps types in clinical practice. This study aimed to evaluate and compare perineal pressure and forces on the baby during nonrotational forceps-assisted births using Simpson-Braun forceps, Kielland forceps, and Thierry spatulas on a simulation model.

METHODS

This experimental study involved six obstetricians conducting 108 forceps-assisted births on a simulation model. Instruments were assessed for their impact on perineal pressure, traction force, and operator-assessed difficulty.

RESULTS

Thierry's spatulas exerted the lowest force on the baby, while Kielland forceps exhibited the lowest perineal pressure, though not statistically significant. An experienced obstetrician demonstrated less perineal pressure with Simpson forceps. Notably, no significant differences in difficulty were observed between instruments.

CONCLUSION

This study highlights distinctions in forceps performance, with Thierry spatulas applying the least force on the fetal head, while an experienced obstetrician fared better with Simpson forceps in terms of perineal pressure. Kielland forceps remain a viable alternative for nonrotational forceps births, showing comparable outcomes.

Prevalence of levator ani avulsion in a multicenter study (PAMELA study)

PURPOSE

The objective is to determine the prevalence of levator ani muscle (LAM) avulsion using four-dimensional ultrasound in primiparous women after vaginal delivery and according to delivery mode.

METHODS

This prospective, multicenter study included 322 women evaluated at 6-12 months postpartum by four-dimensional transperineal ultrasound to identify levator ani muscle avulsion. The researcher who performed the ultrasound was blinded to all clinical data. Meaningful data about the birth were also recorded: mode of delivery, mother's age and body mass index, duration of second stage, episiotomy, perineal tearing, anesthesia, assistant, head circumference and fetal weight.

RESULTS

303 volumes were valid for evaluation. The overall prevalence of levator ani muscle avulsion was 18.8% (95% CI 14.4-23.2%). In our multivariate analysis, only mode of delivery reached statistical significance as a risk factor for levator ani muscle avulsion (p < 0.001). The prevalence according to the different modes of delivery was 7.8% in spontaneous delivery, 28.8% in vacuum-assisted and 51.1% in forceps-assisted delivery. Compared with spontaneous delivery, the OR for LAM avulsion was 12.31 with forceps (CI 95% 5.65-26.80) and 4.78 with vacuum-assisted delivery (CI 95% 2.15-10.63).

CONCLUSIONS

Levator ani avulsion during vaginal delivery in primiparous women occurs in nearly one in every five deliveries. Delivery mode is a significant and modifiable intrapartum risk factor for this lesion. The incidence is lower in spontaneous delivery and significantly increases when an instrument is used to assist delivery, especially forceps.