| The progress and final outcome of labor are influenced by 4 factors (1) thepassage (the bony and soft tissues of the maternal pelvis), (2) the powers (thecontractions or forces of the uterus), (3) the passenger (the fetus)and (4) the psyche .Abnormality of any of these components ,singly or in combination ,may result indystocia .The passage is not subject to change by therapeutic manipulation duringdelivery;the powers and the passenger can be influenced by medications or bymanual or forceps intervention .propulsion and expulsion of the fetus is brought aboutby contactions of the uterus ,reinforced during the second stage by voluntary orinvoluntary muscular action of the abdominal wall-"pushing". Uterus dysfunction ,characterized by infrequent low-intensity contractions ,is common with significantdisproportion because the uterus dose not often self-destruct when faced withmechanical obstruction . Both hypertonic uterine dysfunction and incoordinateuterine dysfunction may result in serious consequences to mother or fetus .Infection isa serious danger to which mother and fetus are exposed in labors complicated byprolonged labor ,especially in the setting of ruptured membranes . Bacteria inamnionic fluid traverse the amnion and invade deciduas and chronic vessels , thusgiving rise to maternal and fetal bacteremia and sepsis . Fetal pneumonia , caused byaspiration of infected amnionic fluid is another serious consequence . Intrapartuminfection is not only a maternal complication but also an important cause of fetal andneonatal death . When the fetal presenting part is firmly weighed into the pelvic inletbut does not advance for a considerable time ,portions of birth canal lying between itand the pelvic wall may be subjected to excessive pressure .Because of impairedcirculation ,necrosis may result and become evident several days after delivery withappearance of vesicovaginal ,vesicocervical or rectovaginal fistulas . Injury to thepelvic floor muscles or to their nerve supply or to the interconnecting fascia is aninevitable consequence of vaginal delivery , particularly if the delivery isdifficult .During childbirth the pelvic floor is exposed to direct compression fromthe fetal head as well as downward pressure from maternal expulsive efforts . Theseforces stretch and distend the pelvic floor resulting in functional and anatomicalalternations in the muscles , nerves ,and connective tissues . Intrauterine fetalanoxemia can cause intracranial hemorrhage ,which may impacts infantile intelligencedevelopment in future. Furthermore ,rate of operative vaginal delivery increaseaccording with uterine inertia . If the labor force survey is practiced duringlabor ,doctors can find the abnormality and take the interventional measures as soonas possible .Doing this ,the latent hurt on mother and child effected by bad birthoutcome can be decreased and the labor force survey can provide impersonalevidence for prospective interventional measures .The diagnosis of labor abnormalityare all retrospective and if doctors took measures later , it would provide matter forconverting quote .There is no impersonal evidence if doctors estimate the labor forceby palpation with their hands .Through our study ,we can find a quantitive criterionfor the power during labor .The internal measurement for intrauterine pressure hasbeen studied for many times before . Although it is accurate ,its complex manipulationand its side-effect such as infection and scathe restrict its clinical application .Wecan not obtain the true intrauterine pressure with external measurement ,but in ourstudy we use it because it can be manipulated easily and continually and it can notcause infection or scathe .It is generally accepted that uterine activity is regulated by complex and mutualinteractions among sex steroid hormones ,myometrial contractility , autonomicinnervation , [excitatory cholinergic, excitatory (α-adrenoceptor) and inhibitory (β-adrenoceptor) adrenergic and peptidergic nerves] and some autacoids (histamine ,5-hydroxytryptamine, prostaglandins and nitric oxide).since it is found in 1993 ,Adrenomedullin (AM) attract more and more attention .We can know that AM exertitself and hold the balance in female reproductive-incretion because it can beexpressed by uterus ,ovary and anterior lobe . Adrenomedullin concentration inplacenta ,uterus ,maternal blood and cord blood increases during normalpregnancy .AM can accelerate the speed of fetal growth and development. AMproduced by amnion and chorion increasing during delivery proves that AMparticipate in the onset of labor . In patients with gestational hypertension ,AMconcentration in fetal-placenta circulation increases but in plasma it mayincreases ,decrease or have no change compared with normal pregnant women .Inpatients with gestational diabetes , AM concentration in amniotic fluid increases ,butin maternal or fetal plasma it has no significant change compared with normalpregnant women .Recently ,there is not much study about its effect on uterinecontractility .We want to clarify the relationship between AM and uterine contractilitythrough the mensuration of AM concentration in retroplacental blood .OBJECTIVE :The purpose of this study was to find the range and difference ofsimulative montevideo units witch has been obtained with external monitor indifferent outcome of delivery and to offer impersonal evidence for prospectiveinterventional measures and forecasting outcome of delivery .The other purpose ofthis study was to analyze the quantitive relationship between AM and uterinecontractility through the mensuration of AM concentration in retroplacental blood andto clarify its effect in human labor.MATERIALS AND METHODS: A total of 90 parturient were included in thestudy. Group1:58 were delivered spontaneously and vaginally;Group 2: 9 weredelivered vaginally but with forceps operation .all women in this group were givenoutlet forceps (biparietal diameter reaching to pelvic floor and fetal presentationreaching to vaginal orifice) or low forceps (biparietal diameter crossing ischial spineand fetal presentation reaching to pelvic floor ,s+3 or more);Group 3:23 weredelivered with cesarean section (12 of these doing so for delayed labor or arrestedlabor) .Each patient had been surveyed intrauterine pressure with externalmeasurement for 20 minutes separately in latent and active phase .We got thesimulative montevideo units (sMU) through adding each uterine contractility within20 minutes and found the difference among these three groups with analysis ofvariance (ANOVA) and t-test .Group A:38 out of group 1 without oxytocin during thefirst stage of labor;Group B: 20 out of group 1 who used oxytocin for augment of thepower during the first phase;Group C: 9 were delivered vaginally but with forcepsoperation and 11 were delivered with cesarean section . In each patient of thesegroups , retroplacental blood were collected. AM concentration was measured byusing radioimmunoassay and we analyzed the relationship between AM concentrationin retroplacental blood and uterine contractility with linear regression analysis.RESULTS: There was no significant difference among sMU in latent phase ofgroup 1,group 2 and group 3 and in active phase , pregnant women in group 3 showedsignificantly lower sMU than the other two groups .AM concentrations inretroplacental blood and uterine contractility presented negative correlation andpregnant women showed lower AM concentrations in group A than group C . Therewas no significant difference between group A than group B.CONCLUSION : Labor force in latent phase can not determine the patterns ofdelivery and there may be valuable to find uterine inertia in active phase .It is moremeaningful to analyze the variety of one parturient by herself than to compare thevariety among individual . Bad labor outcome can not be avoided although laborpower manifests normal change in latent and active phase .So we should check fetalposition and find the abnormality as soon as possible once the labor power changedimperfectly .It is essential to survey the labor power and to induct parturients"pushing" correctly in the second stage of labor . AM can inhibit uterine contractilitybut its mechanism is still unknown .It is hopeful to put AM in use of prematuredelivery and uterine over-efficiency . |
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