Prolonged Dystocic Labor in Neuraxial Analgesia and the Role of Enkephalin Neurotransmitters: An Experimental Study

Abstract

The investigation studied the enkephalinergic neuro fibers (En) contained in the Lower Uterine Segment (LUS) during the prolonged dystocic labor (PDL) with Labor Neuraxial Analgesia (LNA). PDL is generally caused by fetal head malpositions in the Occiput Posterior Position (OPP), Persistent Occiput Posterior Position (POPP), in a transverse position (OTP), and asynclitism (A), and it is detected by Intrapartum Ultrasonography (IU). The En were detected in the LUS samples picked up during cesarean section (CS) of 38 patients undergoing urgent CS in PDL, compared to 37 patients submitted to elective CS. Results were statistically evaluated to understand the differences in En morphological analysis by scanning electron microscopy (SEM) and by fluorescence microscopy (FM). The LUS samples analysis showed an important reduction in En in LUS of CS for the PDL group, in comparison with the elective CS group. The LUS overdistension, by fetal head malpositions (OPP, OTP, A) and malrotations, lead to dystocia, modification of vascularization, and En reduction. The En reduction in PDL suggests that drugs used during the LNA, usually local anesthetics and opioids, cannot control the “dystocic pain”, that differs from normal labor pain. The IU administration in labor and the consequent diagnosis of dystocia suggest stopping the numerous and ineffective top-up drug administration during LNA, and to shift the labor to operative vaginal delivery or CS.

Intrapartum ultrasound and mother acceptance: A study with informed consent and questionnaire

“…Malvasi et al . demonstrates that the overdistention of the LUS by fetal head in malposition determine the structural alteration both in neurofibres and neurotransmitters [46] , [47] . This study was conducted during the COVID-19 [48] , [49] pandemic and biofeedback during pregnancy has been shown to reduce maternal anxiety, especially when the presence of relatives in the ambulatory wasn’t’allowed.…”

Localization of Catecholaminergic Neurofibers in Pregnant Cervix as a Possible Myometrial Pacemaker

“…It is also known that epinephrine decreases after regional analgesia and that adrenaline and noradrenaline are tocolytic at concentrations encountered in laboring women because of a greater presence of beta-adrenergic receptors in the pregnant uterus [ 50 ]. Pain relief after combined spinal-epidural (CSE) analgesia may cause a transient impairment in the action and level of maternal catecholamine, leading to uterine hyperactivity and fetal heart rate (FHR) abnormalities [ 58 , 59 ].…”

Oxytocin augmentation and neurotransmitters in prolonged delivery: An experimental appraisal

“…The impact of dystocia and the tensile characteristics and changes of the LUS in previous caesarean scars were documented by Buhimschi et al [6] . Malvasi et al revealed that in the PDD there is a morphometric reduction of adrenergic fibers, evaluated by SEM and FM [7] , and of enkephalinergic neurofibers in comparison to non-progressive dystocic labor (NPDD) [8] . This study investigated, by SEM and FM, the presence of oxytocinergic Nfc in NPDD and PDD during cesarean section (CS).…”