OBJECTIVE: In this study we use transperineal ultrasound to identify how many women will achieve a normal vaginal delivery without substantial damage to the levator ani or anal sphincter muscles, and to create a model to predict patient characteristics associated with successful atraumatic normal vaginal delivery.

STUDY DESIGN: This is a retrospective, secondary analysis of data sets gathered in the context of an interventional perinatal imaging study. A total of 660 primiparas, carrying an uncomplicated singleton pregnancy, underwent an antepartum and postpartum interview, vaginal exam (Pelvic Organ Prolapse Quantification), and 4-dimensional translabial ultrasound. Ultrasound data were analyzed for levator trauma and/or overdistention and residual sphincter defects. Postprocessing analysis of ultrasound volumes was performed blinded against clinical data and analyzed against obstetric data retrieved from the local maternity database. Levator avulsion was diagnosed if the muscle insertion at the inferior pubic ramus at the plane of minimal hiatal dimensions and within 5 mm above this plane on tomographic ultrasound imaging was abnormal, ie the muscle was disconnected from the inferior pubic ramus. Hiatal overdistensibility (microtrauma) was diagnosed if there was a peripartum increase in hiatal area on Valsalva by >20% with the resultant area ≥25 cm2. A sphincter defect was diagnosed if a gap of >30 degrees was seen in ≥4 of 6 tomographic ultrasound imaging slices bracketing the external anal sphincter. Two models were tested: a first model that defines severe pelvic floor trauma as either obstetric anal sphincter injury or levator avulsion, and a second, more conservative model, that also included microtrauma.

RESULTS: A total of 504/660 women (76%) returned for postpartum follow-up as described previously. In all, 21 patients were excluded due to inadequate data or intercurrent pregnancy, leaving 483 women for analysis. Model 1 defined nontraumatic vaginal delivery as excluding operative delivery, obstetric anal sphincter injuries, and sonographic evidence of levator avulsion or residual sphincter defect. Model 2 also excluded microtrauma. Of 483 women, 112 (23%) had a cesarean delivery, 103 (21%) had an operative vaginal delivery, and 17 (4%) had a third-/fourth-degree tear, leaving 251 women who could be said to have had a normal vaginal delivery. On ultrasound, in model 1, 27 women (6%) had an avulsion and 31 (6%) had a residual defect, leaving 193/483 (40%) who met the criteria for atraumatic normal vaginal delivery. In model 2, an additional 33 women (7%) had microtrauma, leaving only 160/483 (33%) women who met the criteria for atraumatic normal vaginal delivery. On multivariate analysis, younger age and earlier gestation at time of delivery remained highly significant as predictors of atraumatic normal vaginal delivery in both models, with increased hiatal area on Valsalva also significant in model 2 (all P ≤ .035).

MATERIALS AND METHODS: We conducted a 6-year retrospective cross-sectional study from the 1st January 2016 until 31st December 2021. Clinical, demographic characteristics, perioperative parameters, operative indications, blood loss, maternal/neonatal outcomes and complications were analysed. Patients were subdivided, analysed and studied in two subgroups- emergency hysterectomy (EH) and planned hysterectomy (PH).

RESULTS: There were 65 cases of peripartum hysterectomy out of total 100,567 deliveries, with a prevalence rate of 0.06%. Overall, the majority of patients were multiparous (96.9%), having previous caesarean scar (73.8%) or diagnosed with placenta praevia (75.4%). More than half of the total patients (61.5%) have both previous caesarean scar and concomitant placenta praevia. EH was carried out in 39(60%) patients while 26(40%) patients underwent PH. The only indication for surgery in the PH group (100%) was abnormal placentation while the most common indication for surgery in the EH group (53.8%) was postpartum haemorrhage related to abnormal placentation. Patients who underwent EH were more likely to have massive blood loss (p=0.001), require ICU admissions (p=0.001), have DIVC cycles transfused (mean [SD] regime: 1.35 [0.95] vs 0.54 [0.99]; p=0.002), have lower postoperative haemoglobin level (mean [standard deviation, SD] haemoglobin: 9.23g/l [SD1.8] vs. 10.8 g/l [SD1.86]; p=0.001) and have higher difference between pre/post operative haemoglobin level (mean [SD] haemoglobin difference: 1.78g/l [SD6.34] vs 0.32g/l [SD1.7]; p=0.008) compared to patients with PH. Red blood cell transfusion, operating time, length of stay, weight of babies and Apgar score between two groups showed no significant differences. A significant reduction of blood loss between the first and the second half duration of the study (mean [SD] blood loss: 6978 ml [SD 4999.45] vs. 4100ml [SD2569.48]; p=0.004) was also observed. In the emergency group, 'non-placental cause' EH required significantly more red blood cell transfusion than 'placental cause' (p<0.05) while in the PH group, no significant difference was observed between the occlusive internal iliac artery 'balloon' and 'no balloon' subgroup in terms of operating time, total blood loss or blood transfusion. Overall complications showed more cases of post operative fever and relaparotomy in the EH group (18.4% vs. 7.6%) while urinary tract injuries including injuries to bladder and ureter occurred only in the PH group (9.4% vs. 0%).