Magnetic resonance imaging in late pregnancy to improve labour and delivery outcomes - a systematic literature review.

BACKGROUND: Magnetic resonance imaging (MRI) provides excellent soft tissue visualisation which may be useful in late pregnancy to predict labour outcome and maternal/neonatal birth trauma. OBJECTIVE: To study if MRI in late pregnancy can predict maternal and neonatal outcomes of labour and birth. METHODS: Systematic review of studies that performed MRI in late pregnancy or immediately postpartum. Studies were included if they imaged maternal pelvic or neonatal structures and assessed birth outcome. Meta-analysis was not performed due to the heterogeneity of studies. RESULTS: Eighteen studies were selected. Twelve studies explored the value of MRI pelvimetry measurement and its utility to predict cephalopelvic disproportion (CPD) and vaginal breech birth. Four explored cervical imaging in predicting time interval to birth. Two imaged women in active labour and assessed mouldability of the fetal skull. No marker of CPD had both high sensitivity and specificity for predicting labour outcome. The fetal pelvic index yielded sensitivities between 59 and 60%, and specificities between 34 to 64%. Similarly, although the sensitivity of the cephalopelvic disproportion index in predicting labour outcome was high (85%), specificity was only 56%. In women with breech presentation, MRI was demonstrated to reduce the rates of emergency caesarean section from 35 to 19%, and allowed better selection of vaginal breech birth. Live birth studies showed that the fetal head undergoes a substantial degree of moulding and deformation during cephalic vaginal birth, which is not considered during pelvimetry. There are conflicting studies on the role of MRI in cervical imaging and predicting time interval to birth. CONCLUSION: MRI is a promising imaging modality to assess aspects of CPD, yet no current marker of CPD accurately predicts labour outcome. With advances in MRI, it is hoped that novel methods can be developed to better identify individuals at risk of obstructed or pathological labour. Its role in exploring fetal head moulding as a marker of CPD should be further explored.

Predicting the level of difficulty of the double-stapling technique in laparoscopic total mesorectal excision.

BACKGROUND: The transection of rectum and fashioning of anastomosis is a crucial step in laparoscopic total mesorectal excision (TME) and the double-stapling technique (DST) is often employed. This study aimed to evaluate the factors that were associated with difficult DST. METHOD: Cases of laparoscopic TME were retrospectively reviewed. The clinico-anatomical parameters were retrieved from a prospectively maintained database. In addition, pelvic dimensions were taken by reviewing the magnetic resonance imaging scan. The number of stapler cartridges used for intracorporeal transection of rectum was used as a surrogate for the level of difficulty of DST and its relationship with various parameters were evaluated. RESULTS: There were a total of 121 consecutive cases analyzed. The mean number of stapler cartridges used was 2.1 ± 0.7. Pelvic inlet (p = 0.002) and tumor height (p = 0.015) were predictors of the number of cartridges used, R2 = 0.366. A model was developed to predict the likelihood of transecting the rectum with two or less stapler cartridges, which included the following parameters: gender, pelvic inlet, interspinous distance, intertuberous distance, and tumor height. The predicted probability also correlated with overall operation time (p = 0.009) and anastomotic leakage (p = 0.023). CONCLUSION: The difficulty of DST was associated with patient's clinico-anatomical factors. Surgeons can consider other feasible alternatives, like transanal anastomosis, when a technically challenging DST is anticipated.

Predictive Value of MRI Pelvimetry in Vaginal Delivery and Its Practicability in Prolonged Labour-A Prospective Cohort Study.

BACKGROUND: Pelvic dimensions are crucial variables in the labour process. We used magnetic resonance imaging (MRI) pelvimetry to predict the probability of vaginal delivery and distinguish the cephalopelvic disproportion risk in women with prolonged active labour. METHODS: This prospective cohort study enrolled term nulliparous women willing to undergo MRI pelvimetry and a trial of labour. A nomogram, with vaginal birth as the outcome, was developed and evaluated by calibration curve and decision curve analyses. The pairwise association between maternal and fetal parameters and a prolonged first stage of labour was quantified. RESULTS: Head circumference (HC), abdominal circumference (AC), intertuberous distance (ITD), interspinous diameter (ISD), and body mass index (BMI) were introduced to develop a nomogram with good diagnostic performance (area under the curve = 0.799, sensitivity = 83%, and specificity = 73%). The cephalopelvic index of diameter (CID) in 54 women with a prolonged first stage of labour was much smaller in those who delivered via cesarean section compared with those who delivered vaginally (18.09 ± 1.14 vs. 21.29 ± 1.06; p = 0.046). CONCLUSIONS: An MRI pelvimetry-based nomogram may predict the probability of vaginal delivery. Practitioners should reassess the pelvimetry parameters to decide whether the trial of labour should be continued if it is prolonged.

Magnetic resonance imaging pelvimetry predicts the technical difficulty of rectal surgery.

BACKGROUND: The relationships between the pelvimetry and technical difficulties in performing rectal surgery for mid-low rectal cancer remain unclear. METHODS: Two hundred and twenty-one cases of mid-low rectal cancer patients who underwent sphincter-preserved total mesorectum excision (TME) were analyzed. The data of the pelvimetry and the relative position between trocar site and tumor were measured with magnetic resonance imaging (MRI). RESULTS: Univariate analysis showed that the interspinous diameter, the sacrococcygeal distance, and the angle of sacral promontory inclination were significantly associated with the technical difficulty during laparoscopic surgery, but only the interspinous diameter remained an independent risk factor in multivariate analysis. The simulated trocar angle θ was an independent risk factor affecting the operation time during laparoscopic surgery, simulated trocar angle η was significantly related to intraoperative blood loss in both laparoscopic surgery and transanal TME (taTME) surgery groups. CONCLUSION: Interspinous diameter can predict difficulty in laparoscopic surgery and may provide useful information for preoperative planning and consideration of approach.

MRI-based pelvimetric measurements as predictors for a successful vaginal breech delivery in the Frankfurt Breech at term cohort (FRABAT).

OBJECTIVES: The purpose of this study was to investigate the role of the maternal pelvis, assessed by MRI pelvimetry in nulliparous women expecting a term fetus in breech presentation, to predict a successful and safe vaginal birth. STUDY DESIGN: In this monocentric and anonymized cohort study, we enrolled 367 nulliparous women with breech presentation at 39+0 to 41+0 weeks of gestation during a period of 8 years at the University Women's Hospital in Frankfurt/Main. Pelvic measurements were obtained by standard MRI imaging. We correlated the obstetric conjugate, the pubic angle and the distance between the ischial tuberosities (intertuberous distance) with the maternal and fetal outcomes of vaginally intended breech births. The data was evaluated using logistic regression analysis. RESULTS: 241 of 367 participants (65.7%) experienced a successful vaginal delivery whereas 126 patients (34.3%) were subjected to secondary cesarean section. An increasing obstetric conjugate was significantly associated with an increasing rate of successful vaginal deliveries. No significant correlation of the intertuberous distance and the pubic angle with the mode of delivery could be shown. Although statistically not significant, we were able to define cut-off values of 10.9 cm in the intertuberous distance and 70° in the pubic angle; below these values, no successful vaginal delivery was recorded. No significant differences in the short-term outcomes were seen between the neonates of the vaginal delivery and the cesarean section groups. Inter- and intraobserver variability showed excellent reproducibility for all MRI parameters. CONCLUSION: The obstetric conjugate correlates with the rate of vaginal deliveries in nulliparous women at term and can be used as a useful criterion for pre-selection and counseling of women with breech presentation and the desire for a vaginal delivery.