Structured clinical examinations in labor: rekindling the craft of obstetrics

Obstetric factors and neonatal outcomes of depressed skull fractures in newborns

PURPOSE

To determine the obstetric factors affecting the development of depressed skull fracture in neonates.

MATERIALS AND METHODS

This was a retrospectively cohort study on neonates born between July 2016 and August 2021. Neonates diagnosed with depressed skull fractures within one week of birth through X-ray and/or brain ultrasonography were included, and their mothers' obstetric characteristics were reviewed.

RESULTS

There were 12 cases in 6791 live births. Five women were over 35 years old. All except two were nulliparous. Five cases were delivered from labor induction and others presented with spontaneous labor. Except for two cases, delivery occurred within an hour after full cervical dilatation. Two cases were assisted by vacuum. None displayed fetal distress signs such as low Apgar scores below 7, meconium staining, and umbilical cord pH under 7.2. All depressed fractures were found in the right parietal area. Three cases resulted in focal hyperechoic lesion in brain ultrasonography and two of them showed small hemorrhage-like lesion in magnetic resonance imaging. All depressed skull fractures improved within 6 months in followed X-rays or ultrasonography.

CONCLUSIONS

There was no definitely associated obstetric condition for depressed skull fracture of neonates although nulliparous women were majority of the affected cases.

Descent of the presenting part assessed with ultrasound

Fetal head descent can be expressed as fetal station and engagement. Station is traditionally based on clinical vaginal examination of the distal part of the fetal skull and related to the level of the ischial spines. Engagement is based on a transabdominal examination of the proximal part of the fetal head above the pelvic inlet. Clinical examinations are subjective, and objective measurements of descent are warranted. Ultrasound is a feasible diagnostic tool in labor, and fetal lie, station, position, presentation, and attitude can be examined. This review presents an overview of fetal descent examined with ultrasound. Ultrasound was first introduced for examining fetal descent in 1977. The distance from the sacral tip to the fetal skull was measured with A-mode ultrasound, but more convenient transperineal methods have since been published. Of those, progression distance, angle of progression, and head-symphysis distance are examined in the sagittal plane, using the inferior part of the symphysis pubis as reference point. Head-perineum distance is measured in the frontal plane (transverse transperineal scan) as the shortest distance from perineum to the fetal skull, representing the remaining part of the birth canal for the fetus to pass. At high stations, the fetal head is directed downward, followed with a horizontal and then an upward direction when the fetus descends in the birth canal and deflexes the head. Head descent may be assessed transabdominally with ultrasound and measured as the suprapubic descent angle. Many observational studies have shown that fetal descent assessed with ultrasound can predict labor outcome before induction of labor, as an admission test, and during the first and second stage of labor. Labor progress can also be examined longitudinally. The International Society of Ultrasound in Obstetrics and Gynecology recommends using ultrasound in women with prolonged or arrested first or second stage of labor, when malpositions or malpresentations are suspected, and before an operative vaginal delivery. One single ultrasound parameter cannot tell for sure whether an instrumental delivery is going to be successful. Information about station and position is a prerequisite, but head direction, presentation, and attitude also should be considered.

Association between ultrasound measured angle of progression and remaining time in labor: a systematic review

OBJECTIVES

To evaluate the association between ultrasound measured angle of progression (AoP) during labor and time to delivery (TTD) or second stage of labor duration (SSLD).

METHODS

This systematic review (SR) was reported according to PRISMA statement 2020. Databases investigated were MEDLINE, CINHAL, Embase, Scopus, Web of Science. Other sources were references or related articles of included studies, Google Scholar, clinicaltrials.gov, thesis, expert groups. Main keywords: angle of progression, transperineal ultrasound, delivery, labor. Inclusion criteria were observational studies, single term pregnancy, cephalic presentation, AoP measurement during the first stage of labor or at the beginning of the second stage, without date restrictions. Language included: English, Italian, French, Spanish. Studies selection, evaluation of the risk of bias with Quality in Prognosis Studies (QUIPS) tool, and data extraction were carried out by two authors blindly and independently, with disagreement resolution by a third author. Qualitative summary of the results. This SR was registered on PROSPERO, number CDR42021232015.

RESULTS

Of 428 records, 14 were included, published from 2009 to 2021, cumulatively analyzing 2498 women. All studies highlighted an inverse relationship between AoP and TTD. Some have identified an AoP cutoff, contained in a range between 110° and 129°, beyond which the duration of labor is significantly shorter. Others, a range between 137° and 160°, beyond which the duration of the expulsive period is significantly shorter. Finally, some factors influence this association: parity, epidural, and oxytocin.

CONCLUSIONS

This SR confirms a significant association between AoP in labor and TTD. In clinical practice, AoP could help to predict the duration of labor, facilitating decision-making. The main limitations of this SR were the low number of included studies, their heterogeneity, and the high risk of bias related to confounding factors. For future research, further studies are needed to increase the strength of the evidence, obtain stratified results according to patients' characteristics and investigate groups of patients who have not yet been evaluated.