Measurement of retropubic tissue thickness using intrapartum transperineal ultrasound to assess cephalopelvic disproportion

Abstract

PurposeFirst, to describe a new method of assessing cephalopelvic disproportion by measuring the retropubic tissue thickness (RTT), and second, to determine whether RTT was associated with an eventual delivery by cesarean section.MethodsThree-dimensional transperineal ultrasound scans were performed on 129 laboring nulliparous women to obtain 3-dimensional volume datasets for assessing RTT. RTT was measured off-line by three operators (A, B, and C) as the shortest distance between the capsule of the pubic symphysis and the outer border of the fetal skull. The intraoperator repeatability of operator A and the interoperator reproducibility among A, B, and C were determined. The RTT in women who were delivered by cesarean section due to failure to progress was compared to that of women who had a vaginal delivery.ResultsThe intraoperator repeatability for RTT was 1.2 mm. The overall RTT interoperator interclass correlation was 0.97 (0.95-0.98). The RTT in women who had a spontaneous, instrumental, or cesarean delivery was 1.16±0.32 cm, 1.12±0.25 cm, and 0.94±0.25 cm, respectively. Women who were delivered by cesarean section had a significantly smaller RTT than women who had a spontaneous delivery (P=0.008). There was no statistically significant difference in RTT between patients who had a normal vaginal delivery and patients who had an instrumental delivery (P=0.990), or between those who had an instrumental delivery and those who had a cesarean delivery after the Bonferroni correction (P=0.120).ConclusionRTT can be measured with satisfactory intraoperator repeatability and interoperator reproducibility. RTT was significantly smaller in women who eventually had a cesarean delivery than in those who had a vaginal delivery.

Ultrasonic assessment has high sensitivity for pregnant women with previous cesarean section occurring uterine dehiscence and rupture

“…Several factors influence the LUS rupture risk of pregnancy with prior CS, including inter-pregnancy interval, number of previous CS, maternal age, wound infection after the CS, previous classical or inverted T incision and previous uterine rupture, type of prior hysterotomy closure, suture materials, fetal weight, uterine induction with oxytocin or prostaglandins, induction using mechanical methods, remarkable decrease of retropubic tissue thickness, and thin thickness of LUS with CS scar measured by US. [ 4 – 9 , 14 , 19 ] All pregnant women with CS were monitored continuously to term by 4 to 7 weeks from the time of measurement of LUS thickness of 1.0 mm or less in this study, during the monitoring time, 9.34% (10/107) women developed LUS rupture. This suggests that if the gestation has not come to the term, it is still reasonable to monitor to the term, other than to undergo preterm CS birth.…”

Dynamic finite-element simulations reveal early origin of complex human birth pattern

“…288-1, 7.6–8.6 mm in Sts 14, and 8.0 mm in MH2 (Table 1 ). This contrasts to the average fetopelvic soft tissue thickness of about 9.5 mm (associated with emergency Caesarean section in modern humans) to 12.6 mm (associated with vaginal delivery) to which it is compressed in the birth canal 30 (see Methods); the fetopelvic soft tissue consists of the fetal scalp, the amnion, chorion and the mean of the retropubic and presacral soft tissue of the mother’s pelvic canal. Consistent with this, we observed a mean fetopelvic soft tissue thickness in the midsagittal plane of 11.3 mm in our in silico birth simulation of an average modern human female pelvis paired with an average sized fetal skull (Supplementary Fig.…”

“…During labour, soft tissue in the birth canal can be compressed by the fetal head only to a certain degree. Using intrapartum transperineal ultrasound, retropubic tissue thickness in humans during vaginal delivery (measured as the shortest distance between the outer capsule of the pubic symphysis and the outer surface of the skin of the fetal head) has been determined as 11.6 ± 3.2 mm ( N = 59), while Caesarean section was associated with a retropubic tissue thickness of 9.4 ± 2.5 mm ( N = 23) 30 . To this, we added the thickness of the skin of the fetal head as 1.8 mm, measured on intrapartum MRI scans 31 , 80 , 81 .…”

Utilizing intrapartum transperineal ultrasound in the second stage of labor to predict the difficulty in operative forceps delivery

“…The traditional evaluation of head station and position depends on vaginal digital examination, which is subjective, unreliable and poorly reproducible [14][15][16][17]. In contrast, intrapartum ultrasound has been demonstrated to be far more precise in assessing fetal head station and position during delivery [17,18], and it has been used for diagnosing the degree of birth progress and predicting the nal method of delivery [19][20][21][22][23][24][25][26][27].…”