The Pubic Arch Angle: A Study on the Predictability of Labor and Delivery

Abstract

Study objective: to verify if the PAA (angle of the pubic arch) is a predictive data for the mode of delivery, the duration of labour and the expulsion period. Methods: we chose to measure the PAA in 100 women recruited, chosen from the 38th to the 42th week of gestation. The method involves the use of two-dimensional transperineal ultrasound. Data collection took place over a period of time from May to September 2015. The ante-partum data taken into consideration were the patient's name and surname, PAA, parity, age, height; those acquired in the post-partum provide for the calculation in minutes of the active phase of labor, the duration of the expulsion period, the execution of the amniorrhexis and the use of the synthetic oxytocin, the fetal cranial circumference, the fetal weight and the position of the presented part. Results: results discovered ultrasoundly 100 PAA, with an average value of 115.5° and we proceeded by evaluating 90 vaginal births. Infants at birth had a CC with an average value of 34.5 mm. By relating the two variables PAA and CC for the dependent variable "period expulsion in minutes", confirming that the expulsive period depends on the relationship between PAA and CC. The average of the minutes of the expulsion period is 50' in women with a PAA > 111.5° and a CC > 34.5 mm while in women with an PAA > 111.5° the media time is 30' regardless of the CC. It has been shown that oxytocin and amniorrhexis reduce the minutes of the expulsion period only in a case of PAA > 111.5° and a CC > 34.5 mm bringing them from 60' to 23'. Conclusion: the duration of the active phase of labor is not influenced by the PAA but it depends on external factors. In the case of the expulsion period, a predictability of the PAA on its duration is shown if the CC is taken into consideration; as regards the influence of the PAA on the method of delivery, it was not possible to carry out any analysis since all the useful cases had vaginal delivery.