ABSTRACT
OBJECTIVE: To evaluate the impact of body mass index (BMI) on sonographic measurement of head perineum distance (HPD) before operative vaginal delivery (OVD). METHODS: This was a single-center retrospective cohort study (Lille, France) conducted from March 1, 2019 to October 31, 2020 including all singleton and OVD. HPD measurement was systematically performed without and with compression on the perineum soft tissues. The level of station was defined by vaginal examination and three maternal BMI groups were defined (normal BMI [<24.9 kg/m2] vs overweight [25-29.9 kg/m2] vs obese [≥30 kg/m2]). HPD measures were compared between BMI groups and compression, in distinct level of station, using a two-factor analysis of variance including BMI groups, the compression, and the interaction term BMI group compression. RESULTS: A total of 775 women were included: 488 with normal BMI, 181 overweight patients and 106 obese patients. The measurement of HPD before OVD without and with compression on the soft tissues was significantly different between the BMI groups only in the lower part, particularly between normal BMI and obese patients (mean difference (95% CI): 6.6 mm (4.0 to 9.2) without compression; 3.8 (1.1 to 6.4) with compression). CONCLUSION: The values of HPD without and with compression on the soft tissues on the maternal perineum were different according to the maternal BMI concerning lower part station. Thus, it seems important to define thresholds of HPD measures corresponding to each head station levels according to maternal BMI.
ABSTRACT
OBJECTIVE: Determine if head-perineum distance (HPD) measurement before vacuum extraction (VE) was predictive of an obstetric anal sphincter injury (OASIS) occurrence. METHODS: Retrospective, bicentric (Lille and Poissy, France) cohort study conducted from January 2019 to June 2020. All VE in singleton pregnancies of ≥34 weeks were included. HPD measurement was performed without compression of the tissues before each VE. The judgment criterion was the occurrence of an OASIS. RESULTS: Of 12 568 deliveries, VE was performed in 1093 (8.6%). Among these 1093 women undergoing VE, 675 (61.7%) with HPD measurement were included. OASIS was found in 6.5% of women (n = 44; 95% CI 4.5-8.7). HPD was not associated with OASIS (38.5 ± 12.6 mm in women with OASIS vs 37.4 ± 12.0 mm in women without; adjusted OR [aOR] per 5 mm increase = 0.92; 95% CI 0.79-1.06). Increased HPD was associated with higher risk of sequential extraction (aOR = 1.19; 95% CI 1.06-1.32), extraction duration >10 min (aOR = 1.12; 95% CI 1.02-1.23) and shoulder dystocia (aOR = 1.20; 95% CI 1.03-1.40). CONCLUSION: Ultrasound-measured head-perineum distance does not predict the occurrence of obstetric anal sphincter injury during a VE. The interest of HPD is more about predicting the success or difficulty of VE rather its specific complications.
