Ruptur Uteri Dan Fetal Distress

8/20/2019 Ruptur Uteri Dan Fetal Distress

1/28

UTERINE RUPTURE

Williams Obstetrics 24th Edition (HAL 617 Chapter 31)

CLASSIFICATION

Uterine rupture typically is classified as either (1) complete when all layers of the uterine

wall are separated, or (2) incomplete when the uterine muscle is separated but the viscera

peritoneum is intact !ncomplete rupture is also commonly referred to as uterine

dehiscence "s e#pected, morbidity and mortality rates are appreciably $reater when

rupture is compleat %he $reatest ris& factor for either from of rupture is prior cesarean

delivery !n a review of all uterine rupture cases in 'ova cotia between 1** and 1+,

ieser and -as&ett (2..2) reported that 2 percent were in women with a prior cesarean

birth /olm$ren and associates (2.12) described 42 cases of rupture in women with a

prior hysterotomy Of these, 0 were in labor at the time of rupture

DIAGNOSIS

ro$ress of labor in women attemptin$ 3-" is similar to re$ular labor, and there is no

specific pattern that presa$es uterine rupture (5rasec&, 2.12 6 harper, 2.12b) -efore

hypovolemic shoc& deve&ops, symptoms and physical findin$s in women with uterine

rupture may appear bi7arre unless the possibility is &ept in mind 8or e#ample,

hemoperiteoneum from a ruptured uterus may result in diaphra$matic irritation with painreferred to the chest9directin$ one to a dia$nosis of pulmonary or amnionic fluid

embolism instead of uterine rupture %he most common si$n of uterine rupture is a

nonreassurin$ fetal heart rate pattern with variable heart rate decelerations that may

evolve into late decelerations and bradycardia as shown in 8i$ure 0194 ("merican

"cademy of ediatrics and "merican ole$e of Obstetricians and 5ynecolo$ists, 2.12)

!n 0 cases of such rupture durin$ a trial of labor, there were fetal si$ns in 24, maternal in

ei$ht, and both in three (/olm$ren, 2.12) 8ew women e#perience cessation of

contractions followin$ uterine rupture, and the use of intrauterine pressure catheters has

not been shown to assist reliably in the dia$nosis (:odri$ue7, 1*)

!n some women, the appeatance of uterine rupture is indentical to that of placental

abruption !n most, however, the is remar&ably little appreciable pain or tenderness "lso,

because most women in labor are treated for discomfort with either narcotics or epidural


2/28

anal$esia, pain and tenderness may not be readily apparent %he condition usually

becomes evident bacause of fetal distress si$n and occasionally because of maternal

hypovolemia from concealed hemorrha$e

!f the fetal presentin$ part has entered the pelvis with labor, loss of station may be

detected by pelvic e#amination !f the fetus is pattly or totally e#truded from the uterine

rupture site, abdominal palpation or va$inal e#amination may be helpful to identify the

presentin$ part, which will have moved away from the pelvic inlet " firm contracted

uterus may at times be felt alon$side the fetus

DECISION-TO-DELIVER TI!E

With rupture and e#pulsion of the fetus into the peritoneal cavity, the chances for

intact fetal survival are dismal, and reported mortality rates ran$e from ;. to +; percent

Fetal condition depends on the degree to which the placental implantation remains

intact, although this can change within minutes.With rupture the only chance of fetal

survival is afforded by immediate delivery9most often by laparotomy9otherwisse, hypo#ia

is inevitable !f rupture is followed by immediate total placental separation, then very few

intact fetuses will be salva$ed %hus, even in the best of circumstnces, fetal salva$e will

be impaired %he Utah e#periences are instructive here (/olm$ren, 2.12)

Of the 0; laborin$ patients with a uterine rupture, the decision9to9delivery time was

< 1* minutes in 1+, and none of these infants had an adverse neurolo$ical outcome Of

the 1* born = 1* minutes from decision time, the three infants with lon$9term

neurolo$ical impairments were delivered at 01,4., and 42 minutes %here were no deaths,

thus severe neonatal neurolo$ical morbidity developed in * percent of these 0; women

with uterine rupture

!n a study usin$ the wedish -irth :e$istry, ac7marc7y& and collea$ues (2..+)

found that the ris& of neonatal death followin$ uterine rupture was ; percent9a .9fold

increase in ris& compared with pre$nancies not complicated by uterine ripture !n the

'etwor& study seven of the 114 uterine rupture9 percent9associated with a trial of labor

were complicated by the development of neonatal hypo#ic ischemic encephalopathy

(pon$,2..+)


3/28

>aternal deaths from rupture are uncommon, 8or e#ample, of 2; milion women

who $ave birt in anada between 11 and 2..1, there were 1** cases of uterine

rupture, and four of these9.2 percent9resulted in maternal death (Wen, 2..;) !n other

re$ions of the world, however, maternal motality rates associated with uterine rupture are

much hi$her !n a report from rural !ndia, for e#ample, the maternal mortality rate

associated with uterine rupture was 0. percent (hatter?ee,2..+)

HSTERECTO! VERSUS REPAIR

With complete rupture durin$ a trial of labor, hysterectomy may be re@uired !n the

reports by >c>ahon (1) and >iller (1+) and their cowor&ers, 1. to 2. percent of

such women re@uired hysterectomy for hemostasis !n selected cases, however, suture

repair with uterine preservation may be performed heth (1*) described outcomes

from a series of women in whom repair of a uterine rupture was elected rather than

hysterectomy !n 2; instances, the repair was accompanied by tubal sterili7ation %hirteen

of the 41 mothers who did not have tubal sterili7ation had a total of 21 subse@uent

pre$nancies Uterine rupture recurred in four of these9appro#imately 2; persent Usta and

associates (2..+) identified 0+ women with a prior complete uterine rupture delivered

durin$ a 2;9year period in Aebanon /ysterectomy was performed in 11, and in the

remainin$ 2 women, the rupture was repaired %welve if these women had 24

subse@uent pre$nancies, one third of which were complicated by recurrent uterine

rupture !nanother study, however, women with a uterine dehiscence were not more li&ely

to have uterine rupture with a subse@uent pre$nancy (-aron,2.10b)

CO!PLICATIONS "ITH !ULTIPLE REPEAT CESAREAN DELIVERIES

-ecause of the concerns with attemptin$ a terial of labor9even in the women with

e#cellent criteria that forecast succesfull 3-"9most women in the United tates

Under$o elective repeat cesarean delivery %his choice in not without several si$nificant

maternal complication, and rates of these increase inwomen who have multiple repeat

operations %he incidences of some common complications for women with one prior

transverse cesarean delivery who under$o an elective repeat cesarean delivery were show

in tabele 0192 8inally, half of cesarean hysterectomies done at ar&land /ospital are in


4/28

women with one or more prior cesarean deliveries (/ernande7, 2.10)

%he 'etwor& addressed issuer of increased morbidity in a cohort .f 0.,102 women

who had from one to si# repeat cesarean deliveries (ilver, 2..) %his report addressed a

list of morbidities, most of which increased as a trend sith increasin$ number of repeat

operations %he rates of some of the more common or serious complication are depicted

in fi$ure 019; !n addition to the ones shown, rates of bowel or bladder in?ury, admission

to an intensive care unit or ventilator therapy, and maternal mortality, as well as operative

and hospitali7ation len$th, showed si$nificantly increasin$ trends imilar results have

been reported by others ('isenblat, 2..6Usta,2..;) >ore difficult to @uantify are ris&s

for bowel obstructions and pelvic pain from peritoneal adhesive disease, both of which

inctease with each successive cesarean delivery ("ndolf, 2.1.6>an&uta, 2.10)

oo& and collea$ues (2.10) from the United in$dom Obstertic urveillance system

(UO) described adverse se@uelae of women with multiple cesarean deliveries

Outcomes of those under$oin$ a fifth or $reater operation were compared with those

from women havin$ a second throu$h fourth procedure %hose havin$ five or more

cesarean deliveries had si$nificantly increased rates if morbidity compared with rates in

women havin$ fewer than five procedures pecifically, the ma?or hemorrha$e rate

increased 1*9fold6 visceral dama$e, 1+9fold6 critical care admissions, 1;.fold6 and

delivery < 0+ wee&s, si#fold >uch of this morbidity was in the 1* percent who had

placenta previa or accrete syndromes (hap41p+) " percreta may invade the bladder

or other ad?acent structures With this, difficult resection carries an inordinately hi$h ris&

of hysterectomy, massive hemorrha$e with transfusion, and maternal maotality

STATE OF VAGINAL #IRTH AFTER CESAREAN-$%1&

%he Bbest answerC for a $iven women with a prior cesarean delivery in un&nown We

a$ree with scott (2.11) re$ardin$ a Bcommon9senseC approach %hus, the women9 and her

partner if she wishes9are encoura$ed to actively participate with her health9care provider

in the final decision after appropriate counselin$ 8or women who wish %OA" despite a

factor that increases their specific ris&, additions to the consent form are recommended

("merican olle$e of Obstetricians and 5ynecolo$iss, 2.10a) -pnanno and collea$ues

(2.11) have provided such an e#ample


5/28

Williams Obstetrics 24th Edition (hal +.9+0 section 11 D chapter 41)

RUPTURE OF THE UTERUS

Uterine rupture may be primary, defined as accurrin$ in a previously intact or

unscarred unterus, or may be secondary and associated with a pree#istin$ myometrial

incision, in?ury, or anomaly ome of the etiolo$ies associated with uterine rupture are

presented in table 4190 !mportantly, the contribution of each of these underlyin$ causes

has chan$ed remar&ably durin$ the ppast ;. years pecifically, befor 1., when the

cesarean delivery rate was much lower than it is currently and when women of $reat

parity were numerous, primary uterine rupture predominated "s the incidence of

cesarean delivery increased and especially as a subse@uent trial of labor in these women

became prevalent throu$h the 1.s, uterine rupture throu$h the cesarean hysterotomy

scar became preeminent "s discussed in detail in hapter 01 (p1+) alon$ with

diminished enthusiasm for trial of labor in women with prior cesarean delivery, the two

types of rupture li&ely now have e@uivalent incidences !ndeed, in a 2.. study of 41

cases of uterine rupture from the /ospital orporation of "merica, half were in women

with a prior cesarean delivery (orreco,2..)

PREDISPOSING FACTORS AND CAUSES

!n addition to the pprior cesarean hysterotomy incision already discussed, ris& for

uterine rupture include other previous operations or manipulations thah traumati7e the

muometrium E#amples are uterine curetta$e or perforation, endometrial ablation,

myomectomy, or hysteroscopy (ieser, 2..26 elosi, 1+) !n the study by porreco and

collea$ues (2..) cited earlier, seven of 21 women with9out a prior cesarean delivery had

under$one prior uterine sur$ery

!n developed countries, the incidence of rupture was cited by $etahun and associates

(2.12) as 1 in 4*.. deliveriies %he fre@uency of primary rupture appro#imates 1 in

1.,... to 1;,... births (>iller, 1+6orreco, 2..) One reason is a decreased incidence

of women of $reat parity (>aymim, 116>iller, 1+) "nother is that e#cessive or

inappropriate unterine stimulation eith o#ytocin9previously a fre@uent cause9has mostly

disappeared "necdotally, however, we have encountered primary unterine rupture in a

disparate number of women in whom labor was induced with prosta$landin E1


6/28

PATHOGENESIS

:upture of the previously intact uterus durin$ labor most often involver the thinned9

out lower uterine se$ment When the rent is in the immediate vicinity of the cervi#, it

free@uently e#tends trensversely or obli@uely Where the rent is in the portion of the

uterus ad?acent to the broad li$ament, the tear is usually lon$itudinal "lthou$h these

rears develop primarily in the lower uterine se$ment, it is not unusual for them to e#tend

upward into the active se$ment or downward throu$h the cervi# and into the va$ina

(fi$41910) !n some cases, the bladder may also be lacerated (:acha$an, 11) !f the

rupture is of sufficient si7e, the uterine contents will usually escape into the peritoneal

cavity !f the presentin$ fetal part is firmly en$a$ed, however, then only a portition of the

fetus may be e#truded from the uterus 8etal pro$nosis is lar$ely dependent on the de$ree

of placental separation and ma$nitude of maternal hemorrha$e and hypovolemia !n some

cases, the overlyin$ peritoneum remains intact, and this usually is accompanied by

hemorrha$e that e#tends into the broad li$ment to cause a lar$e retroperitoneal hematoma

with e#tensive blood loss

Occasionally, there is an inherent wea&ness in the myomatrium in which the rupture

ta&es place ome e#amples include anatomical anomaalies, adenomyosis, and

connectivetissue defects such as Ehlers9anlos syndrome ("rici, 2.106'i&olaou, 2.10)

!ANAGE!ENT AND OUTCO!ES

%he varied clinical presentations of uterine rupture and its mana$ement are discussed

in detail in chapter 01 (p1+)

!n the recent maternal mortality statistics from the centers for isease ontrol and

revention, uterine rupture accounted for 14 of deaths caused by hemorrha$e (-er$,

2.1.) >aternal morbidity includes hysterectomy that may be necessary to control

hemorrha$e %here is also considerably increased perinatal morbidity and mortality

associated with uterine rupture " ma?or concern is that survivin$ infants develop severe

neurolo$ical impairment (orreco, 2..)


7/28

TRAU!ATIC UTERINE RUPTURE

"lthou$h the distended pre$nant uterus is surprisin$ly resistant to blunt trauma,

pre$nant women sustainin$ such trauma to the abdomen should be watched carefully, for

si$n of a ruptured uterus (hap4+, p;4) Even so, blunt trauma is more li&ely to cause

placental abruption as described subse@uently !n a study by miller and paul (1),

trauma accounted for only three cases of uterine rupture in more than 1;. women Other

causes of traumatic rupture that are uncommon today are those due to internal podalic

version and e#traction, difficult forceps delivery, breech e#traction, and unsual fetal

enlr$ement such as with hydrocephaly

TA#LE &1-3' Se *a+,e, Uter./e R+pt+re

ree#istin$ Uterine !n?ury or "nomaly Uterine in?ury or "bnormality incurred in currentre$nancy

S+r0er ./22./0 the etr.+ 4

esarean delivery or hysterotomy

reviously repaired uterine rupture

>yomectomy incision throu$h or the endometrium

eep cornual resection of interstitial fallopian tube

>etroplasty

C./*.5e/ta +ter./e tra+a 4

"bortion with instrumentation9sharp or suction

curette, sounds harp or blunt trauma9assaults, vehicular accidents,

bullets,&nives

ilent rupture in previous pre$nancy

C/0e/.ta 4

re$nancy in undeveloped uterine horn

efective tissue9>arfan or Ehlers9anlos yndrome

#ere 5e.2er 4

ersistent, !ntense, pontaneous contractions

Aabor stimulation9o#ytocin or prosta$landins

!ntraamnionic instillation9saline or prosta$landins

erforation by internal uterine pressure catheter

E#ternal trauma9sharp or blunt

E#ternal 3ersion

Uterine overdistention9hydramnios, multifetal pre$nancy

D+r./0 5e.2er 4 !nternal version second twin

ifficult forceps delivery

:apid tumultuous labor and delivery

-reech e#traction

8etal anomaly distendin$ lower se$ment

3i$orous uterine pressure durin$ delivery

ifficult manual removal of placenta

A*+.re5 4

lacental accrete syndromes

5estational trophoblastic neoplasia

"denomyosis

acculation of entrapped retroverted uterus


8/28

REFERENCES

Williams Obstetrics F(edited bay) 85ary unnin$ham, enneth GAeveno, teven A

-loom, atherine H pon$, Godi ashe, -arbara A /offman, -rian >asey,

Geanne heffied924 th edition hal 1+ hapter 01 D hal +.9+0 section 11 D

chapter 41, 2.14)


9/28

TA#EL 31-& Se Re*e/5at./, Pre,,./a S+*.et.e, C/*er/./0 a tr.a a ar t Attept V#AC

C+/,e./0 Fa*..t.e, Other

"merican olle$e of

obstetricians and 5ynecolo$ist

(2.10a)

ociety of

Obstetricians and $ynaeclo$ists

of canada (2..;)

:oyal olle$e of Obstetricians

and 5ynaecolo$ists (2..+)

Offter to most women with one

prior low9transverse incision6

consider for two prior low9

tranverse incisions

Offer to women with one prior

transverse low9se$ment cesarean

delivery6 with=1 prior then

3-" li&ely successful but

increased ris&s

iscuss 3-" option with women

with prior low9se$ment cesarean

delivery6 decision between

obstetrician and patient

afest with ability for

immediate cesrean delivery6

patients should be allowed to

accept increased ris& when not

available

hould deliver in hospital in

which timely cesarean delivery

is available6 appro#imate

timeframe o 0. minutes

uitable delivery suite with

continuous care and

monitorin$6immediate

cesarean delivery capability

'ot precluded6 twins,

macrosomia, prior lowvertical

or un&nown type of incision

O#ytocin or foley catheter

induction safe, but

prosta$landins should not be

used6macrosomia, diabetes,

postterm pre$nancy, twins are

not contraindications

aution with twins and

macrosomia

I cesarean delivery63-"I 3a$inal birth after cesarean


10/28

-erief synopses of professional society $uidelines are shown in table 0194 5uidelines that tend to be more conservative are show

in table 019;

TA#LE 31-8' C/,er2at.2e G+.5e./e, t appra*h a tr.a ar 9./0 *e,area/ 5e.2er

F9 ACOG pra*t.*e 0+.5e./e,

E5+*at./ a/5 *+/,e./0

reconceptionally

rovide "O5 patient pamphletEarly durin$ prenatal care

evelop preliminary plan :evisit at least each trimester

-e willin$ to alter decision

/ave facilities availability

R.,: a,,e,,e/t

:eview previous operative note (s)

:eview relative and absolute contraindications

:econside ris& as pre$nancy pro$resses%read carefully J = 1 prior transverse , un&nown incision, twins, macrosomia

Lar a/5 5e.2er

autions for induction9unfavorable cervi#, hi$h station onsider ":O>

"void prosta$landins :espect o#ytocin9&now when to @uit-eware of abnormal labor pro$ress

:espect E8> pattern abnormalities

now when to abandon a trial of labor

"O5 I "merican olle$e of Obstetricians and 5ynecolo$ists6 ":O> I artificial rupture of membranes6 I esarean elivery 6

E8> I eleectronic fetal monitorin$


11/28

Williams Obstetrics 24th Edition (hal 419;.. chapter 24)

FETAL DISTRESS

%he terms fetal distress and birth asphy#ia are to broad and va$ue to be applied

with any precision to clinical situations ( "merican colla$e of obstetricians and

$ynecolo$ists, 2..;) Uncertainty re$ardin$ the dia$nosis based on interpretation of

fetal hearth rate patterns has $iven rise to descriptions such as reassuring or non

rearssuring. %he terms Breassurin$ su$$ests a restoration of confidence by particular

pattern, whereas Bnonreassurin$C su$$ests inability to remove doubt %hese patterns

durin$ labor are dynamic K they can rapidly chan$e from reassurin$ to nonreassurin$

and viceversa !n this situation, obstetrician lose confidence or cannot assua$e doubts

about fetal condition These assessments are subjective clinical judgments that areinevitably subject to imperfection and must be recognized as such.

Pathph,.0

Why is the dia$nosis of fetal distress based on hearth rate patterns so tenuousL

One e#planation, is that these patterns are more a reflection of fetal physiolo$y than of

patholo$y hysiolo$ical control of hearth rate includes various interconnected

mechanisms that depend on blood flow ande o#y$enation >oreover, the activity of

these control mecanisms influenced by the pree#istin$ state of fetal o#y$enation, for

e#ample, as seen with chronic plasental insufficiency !mportantly, the fetus is

tethered by an umbilical cord, whereby blood flow is constanly in ?eopardy

>oreover, normar labor is a process of increasin$ acidemia ( ro$ers 1*) %hus,

normal labor is a process of repeated fetal hypo#ic events resultin$ inevitably in

academia

ut another way, and assumin$ that Basphy#iaC can be defined hypo#ia leadin$ to

acidemia, normal parturition is an as phy#iatin$ event for the fetus

D.a0/,.,

-ecause of the above uncertainties it follows that identifications of Bfetal

distressC based on fetal heart rate patterns is imprecise and controversial !t is well

&nown that e#perts in interpretations of these patterns of ten dissa$re with each order

!n fact, parer (1+), a stron$ advocate of electronic fetal heart rate monitorin$ and an

or$ani7er of the 1+ '!/ fetal monitorin$ wor&shop, li$ht heartedly compared


12/28

the e#perts in attendance to marine i$uanas of the 5alapa$os !slands, to witJ Ball on

the same beach but facin$ different direntions and spittin$ at one another constantlyMC

"yres9de9ampos and collea$ues (1) investi$ated interobserver a$reement of

fetal heart rate pattern interpretation and found that a$reement Kor conversely,

disa$reementNwas related to whether the pattern was normal, suspicious, or

patholo$ical pecifically, e#perts a$reed on 2 percent of normal patterns, 42 percent

of suspicious patterns, and only 2; percent of patholo$ical pattens eith and

cowor&ers (1;) as&ed each of 1+ e#perts to review ;. tracin$s on two occasions, at

least 1 month apart "ppro#imately 2. percent chan$ed their own interpratations, and

appro#imately 2; percent did not a$ree with the interpretations of their colla$ues "nd

althou$h >urphy and associates (2..0) conclude that at least part of the interpretation

problem is due to a lac& of formali7ed education in "merica trainin$ pro$ram, this is

obviously only on a small modifier ut another way, how can the teacher enli$hten

the student if the teacher is uncertainL

Nat./a I/,t.t+te, Heat "r:,hp, Three-T.er Ca,,..*at./ S,te

%he '!/ (1+) held a succession of wor&shops in 1; and 1 to develop

standardi7ed and unambi$uous defitions of fetal heart rate (8/:) tarcin$s and

published recommendations for interpretin$ these patterns !n 2..*, a second

wor&shops was convened to reevaluate the 1+ recommendations and to clarify

terminolo$y (see table 2491) (>acones,2..*) " ma?or result was the recommendation

of a three9tier system for classification of 8/: patterns (table 2492) %he "merican

olle$e of Obstetricians and 5ynecolo$ist (2.10b) subse@uently recommended use of

this tiered system

" few studies have been done to assets the three9tiered systems Gac&son and

cowo&ers (2.11) studied 4*,444 women in labor and found that cate$ory ! (normal

8/:) patterns were observed durin$ labor in ; percent of tracin$s ate$ory !!

(indeterminate 8/:) patterns were found in *41 percent of tracin$s, and cate$ory !!!

(abnormal 8/:) patterns were seen in .1 percent (;4 women) >ost K*4 percent of

women Khad a mi# of cate$ories durin$ labor ahill and collea$ues (2.12)

retrospectively studied the incidence of umbilical cord academia (h +1.)

correlated with fetal heart rate characteristics durin$ the 0. minutes precedin$

delivery 'one of the three cate$ories demonstrated a si$nificant association with cord

blood academia %he "merican olle$e of Obstetricians and 5ynecolo$ist and the


13/28

"merican "cademy of ediatrics (2.14) concluded that a cate$ory ! or !! tracin$ with

a ;9minutes "p$ar score = + or normal arterial blodd acid9base values was not

consistent with an acute hypo#ic9ischemic event

holapur&ar (2.12) also challen$ed the validity of the three tier system because

most abnormal fetal rate patterns fall into the inderterminate cate$ory !!, that is, one

for which no definite mana$ement recommendations can be made !t was further

su$$ested that this resulted from most fetal heart rate decelerations bein$

inappropriately classified as variable decelerations due to cord compression

aree and in$ (2.1.) compared the current situation in the United tates with

that of other countries in which a consensus on classification and mana$ement has

been reached by a number of professional societies ome of these include the :oyal

olle$e of Obstetricians and 5ynecolo$ist, the ociety of Obstetricians and

5ynecolo$ists of anada, the :oyal "ustralian and 'ew Pealand olle$e of

Obstetricians and 5ynecolo$ists and the Gapan ociety of Obstetricians and

5ynecolo$y arer and in$ (2.1.) further comment that the '!/ three9tier

system is inadfe@uate because cate$ory !!Ninderteminate 8/:Nconsist of a Bvast

hetero$enous mi#ture of patternsC that prevent development of a mana$ement

strate$y eter and !&eda (2..+) had previously proposed a color9coded five9tier

system for both 8/: interpretation and mana$ement %here have been two reports

comparin$ the five9tier and three9tier systems -annerman and associates (2.11)

found that the two system were similar in fetal heart rate interpretations for tracin$

that were either very normal or very abnormal oletta and cowo&ers (2.12) found

that the five9tier system had better sensitivity than the three9tier system !t is apparent

that, after ;. years of continuous electronic fetal heart rate monitorin$ use, there is not

a consensus on interpretation and mana$ement recommendations for 8/: patterns

(arer,2.11)

Tae $&'$ Three-t.er eta heart rate ./terpretat./ ,,te

Cate0r I-NOR!AL

!nclude all of the followin$J

• -aseline rate J 11. K 1. bpm

• -aseline 8/: variability J moderate

• Aate or variable decelerations J absent

•Early decelerations J present or absent

• "ccelerations J present or absent


14/28

ate$ory !! K !'E%E:>!'"%E

!nclude all 8/: tracin$s not cate$ori7ed as cate$ory ! or !!!

ate$ory !! tracin$s may represent an appreciable fraction of those encountered in

clinical care E#amples include any of the followin$J

-aseline rate• -radycardia not accompanied by absent baseline variability

• %achycardia

-aseline 8/: 3":!"-!A!%H

• >inimal baseline variability

• "bsent baseline variability not accompanied by recurrent decelerations

• >ar&ed baseline variability

"EAE%"%!O'

• "bsence of induced accelerations after fetal stimulation periodic or episodic

decelerations

• :ecurrent variable decelerations accompanied by minimal moderate baseline

variability

• rolon$ed deceleration Q min 2 but < 1. min

• :ecurrent late decelerations with moderate baseline variability

• 3ariable decelerations with other characterististic, such as slow return to

baseline, Bovershoot,C or BshouldersC

ate$ory !!!

!nclude either J

• "bsent baseline 8/: variability and any of the followin$ recurrent late

decelerations, recurrent variable decelerations, bradycardia

• inuisoidal pattern

-pm I beats per minute 6 8/: I fetal heart rate

8rom >acones, 2..*, with permission

!e*/.+ ./ the a/.t.* +.5

Obstetrical teachin$ throu$hout the past century has included the concept that

meconium passa$e is a potential warnin$ of fetal asphy#ia !n 1.0, G Whitrid$e

Williams observed and attributed meconium passa$e to Brela#ation of the sphincter

ani muscle induced by faulty aeration of the (fetal) bloodC Even so, obstetricians have

also lon$ reali7ed that the detection of meconium durin$ labor is problematic in the

prediction of fetal distress or asphy#ia !n their review, at7 and -owes (12)

emphasi7ed the pro$nostic uncertainty of meconium by referrin$ to the topic as a

Bmur&y sub?ectC !ndeed, althou$h 12 tp 22 percent of labors are complicated by

meconium, only a few are lin&ed to infant mortality !n an investi$ation from ar&land


15/28

/ospital, meconium was found to be a Blow9ris&C obstetrical ha7ard because the

perinatal mortality rate attribubutable to meconium was ! death per 1... live births

('athan,14)

%he theories have been su$$ested to e#plain fetal passa$e of meconium and in

part may e#plain the tenuous conection between its detection and infant mortality

8irst, the phatolo$ical e#planation proposes that fetuses pass meconium in response to

hypo#ia and that meconium therefore si$nals fetal crompomise (wal&er, 1;0)

econd, the physiolo$ical e#planation is that in utero passa$e of meconium represents

normal $astrointestinal tract maturation under neural control (>athews, 1+) " final

theory posits that meconium passa$e follows va$al stimulation from common but

transient umbilical cord entrapment with resultant increased bowel peristalsis

(/on,11) %hus, meconium release may represent physiolo$ical processes

:amin and associates (1) studied almost *... pre$nancies with meconium

stained amniotic fluid delivered at ar&land /ospital >econium aspiration ayndrome

was si$nificantly associated with fetal academia at birth Other si$nificant correlates

of aspiration included cesarean delivery, forceps to e#pedite delivery, intrapartum

heart rate abnormalities, depressed ap$ar scores, and need for assisted ventilation at

delivery "nalysis of the type of fetal academia based on umbilical blood $ases

su$$ested that the fetal compromise associated with meconium aspiration syndrome

was an acute event %his is because most academic fetuses had abnormally increased

O2 values rather than a pure metabolic academia

awes and cowor&ers (1+2) observed that such hypercarbia in fetal lambs

induces $aspin$ and resultant increased amnionis fluid inhalation Govanovic and

'$uyen (1*) observed that meconium $asped into the fetal lun$s caused aspiration

syndrome only in asphy#iated animals :amin and collea$ues (1) hypothesi7ed

that the pathophysiolo$y of meconium aspiration syndrome includes, but is not

limited to, fetal hypercarbia, which stimulates fetal respiration leadin$ to aspiration of

meconium into alveoli Aun$ parenchymal in?ury is secondary to academia K induced

alveolar cell dama$e !n this phatophysiolo$ical scenario, meconium in amniotic fluid

is a fetal environmental ha7ard rather than a mar&er of pree#istent compromise %his

proposed pathophysiolo$ical se@uence is not all inclusive, because is does not account

for appro#imately half of the cases of meconium aspiration syndrome in which the

fetus was not academic at birth

%hus, it was concluded that the hi$h incidence of meconium observed in the


16/28

amniotic fluid durin$ labor often represents fetal passa$e of $astrointestinal contents

in con?unction with normal physiolo$ical processes "lthou$th normal, such

meconium becomes an environmental ha7ard when fetal academia supervenes

!mportantly, such academia occurs acutely, and therefore meconium aspiration is

unpredictable and li&ely unpreventable >oreover, 5reenwood and collea$ues (2..0)

showed that clear amniotic fluid was also a poor predictor !n a prospective study of

*04 women with clear amniotic fluid, they found that clear fluid was an unreliable

si$n of fetal well9bein$

5rowin$ evidence indicates that many infants with meconium aspiration

syndrome have suffered chronic hypo#ia before birth (5hidini,2..1) -lac&well and

associates (2..1) found that .R of infants dia$nosed with meconium aspiration

syndrome had umbilical artery blood / Q +,2., implyin$ that the syndrome was

unrelated to the neonatal condition at delivery imilary, mar&ers of cronic hypo#ia,

such as fetal arythropoietin levels and nucleated red blood cell counts in newborn

infants, su$$est that chronic hypo#ia is involved in many meconium aspiration

syondrome case (ollber$, 2..1J Ga7ayeri,2...)

!n the recent past, routine obstetrical mana$ement of a newborn with meconium9

stained amniotic fluid included intrapartum suctionin$ of the oropharyn# and

nasopharyn# 5uidelines from the "merican "cademia of ediatric and the "merican

olle$e of Obstetricians and 5ynecolo$ists, however, recommend that such infants no

lon$er routinely receive intrapartum suctionin$ because it does not prevent meconium

aspiration syndrome (eelman,2.1.) "s discusses in chapter 02 (2), if the infant is

depressed, the trachea is intubated, and meconium suctioned from beneath the $lottis

!f the newborn is vi$orous, defined as havin$ stron$ respiratory efforts, $ood muscle

tone, and a heart rate = 1.. bpm, then tracheal suction is not necessary and may in?ure

the vocal cords

!ANAGE!ENT OPTIONS

%he principal mana$ement options for si$nificantly variable fetal heart rate

patterns consist of correctin$ any fetal insult, if possible >easure su$$ested by the

"merican olla$e of Obstetritians and 5ynecolo$ists (2.10b,c) are listed in table 249

0 >ovin$ the mother to the lateral position, correctin$ maternal hypotension caused

by re$ional anal$esia, and discontinuin$ o#ytocin serve to improve uteroplasental

paerfusion E#amination is done to e#clude prolapsed cord or impendin$ delivery


17/28

impson and ?ames (2..;) assessed benefits of three maneuvers in ;2 women with

fetal o#y$en saturation sensors already in place %he used intravenous hydration K ;..

to 1... ml of lactated :in$er solution $iven over 2. minutes J lateral versus supine

position J and usin$ a nonrebreathin$ mas& that administered supplemental o#y$en at

1. AFmin Each of these maneuvers si$nificantly increased fetal o#y$en saturation

levels, althou$h the increments were small

TOCOLSIS

" sin$le intravenous or subcutaneous in?ection of .,2; m$ of terbutaline sulfate

$iven to rela# the uterus has been described as a tempori7in$ maneuver in the

mana$ement of nonreassurin$ fetal heart rate patterns durin$ labor %he rationale is

that inhibition of uterine contractions mi$ht improve fetal o#y$enation, thus achievin$

in utero resuscitation oo& and spinnato (14) described their e#perience durin$ 1.

years with tertabuline tocolysis for fetal resuscitation in 0* pre$nancies uch

resuscitation improved fetal scalp blood p/ values, althou$h all fetuses underwent

cesarean delivery %hese investi$ators concluded that althou$h the studies were small

and rarely randomi7ed, most reported favorable results with terbutaline tocolysis for

nonreasurin$ patterns mall intravenous doses of nitro$lycerin K . to 1*. S$ K also

have been reported to be beneficial ( mercier, 1+) %he "merican olla$e of

Obstetricians and 5yneclolo$ist (2.10b) has concluded that there is insufficient

evidence to recommend tocolysis for noreassurin$ fetal heart rate patterns

A!NIOINFUSION

5abbe and cowor&ers (1+) showed in mon&eys that removal of amniotic fluid

produced variable decelerations and that decelerations and that replenishment of fluid

with saline reliaeved the decelerations >iya7a&i and taylor (1*0) infused saline

throu$h an intrauterine pressure catcheter in laborin$ women who had either variable

decelerations or prolon$ed decelarations attributed to cord entrapment uch therapy

improved the harth rate pattern in half of the women who had either variable

decelerations or prolon$ed decelerations attributed to cord entrapment uch theraphy

improved the heart rate pattern in half of the women studied Aater, >iya7a&i and

'evare7 (1*;) randomly assi$ned nulliparous women in labor with cord

compression patterns and found that those who werw treated with amnioinfusion

re@uired cesarean delivery for fetal distress less often


18/28

-ased on many of these early reports, transva$inal amnioinfusion has been

e#tended into three clinical areas %hese include J (1) treatment of variable or

prolon$ed decelerations, (2) prophyla#is for women with oli$ohydramnions, as with

prolon$ed ruptured membranes, and (0) attempts to dilute or wash out thic&

meconium (hap00,p0*)

>any different amnioinfusion protocols have been reported, but most include a

;.. K to *.. >l bolus of warmed normal saline followed by a continuous infusion of

a appro#imately 0 >l per minute (Owen, 1. Jressman, 1) !n another study,

:inehart and collea$ues (2...) randomly $ave a ;.. >l bolus of normal saline at

room temperature alone or ;.. >l bolus plus continuous infusion of 0 >l per minute

%heir study included ; women with variable decelerations, and the investi$ators

found neither method to be superior Wenstrom and associates (1;) surveyed use of

amnioinfusion in teachin$ hospitals in the 1* centers surveyed, and it was estimated

that 0 to 4 percent of all women delivered at these centers received such infusion

otential complications of amnioinfusion are summari7ed in table 2494

Tae $&-& Cp.*at./, A,,*.ate5 ".th A/../+,./ Fr a S+r2e 1;6

O,tetr.*a U/.t,'

CO!PLICATION CENTERS N'(


19/28

and 5ynecolo$ists (2.10a) recommends considerations of amnioinfusion with

persistent variable decelerations

PROPHLACTIC A!NIOINFUSION FOR OLIOGOHDRA!NIOS

"mnioinfusion in women with oli$ohydramnios has been used prophylactically

to avoid intrapartum fetal heart rate pattern from cord occlusion 'a$eotte and

cowo&ers (11) found that this resulted in si$nificantly decreased fre@uency and

severity of variable decelarations in labor /owefer, the cesarean delivery rate or

condition of term infants was not improved !n a randomi7ed investi$ation, >acri and

collea$ues (12) studied prophylactic amnioinfusion in 1+. term and postterm

pre$nancies complicated by both thic& meconium and oli$ohydramnios

"mnioinfusion si$nificantly reduced cesarean delivery rates for fetal distress and

meconium aspiration syndrome !n contrast, O$undipe and associates (14)

randomly assi$ned 11 term pre$nancies with an amnionic fluid inde# < ; cm to

receive prophylactic amnioinfusion or standard obstetrical care %here were no

si$nificant differences in overall cesarean delivery rates, delivery rates for fetal

distress, or umbilical cord acid Kbase studies

A!NIOINFUSION FOR !ECONICU! =STAINED A!NIONIC FLUID

ierce and associates (2...) summari7ed the result of 10 prospective trials of

intrapartum amnioinfusion in 124 women with moderate to thic& meconium9stained

fluid !nfants born to women treated by amnioinfusion were si$nificantly less li&ely to

have meconium below the vocal cords and were lessli&ely to develop meconium

aspiration syndrome than infants born to women not under$oin$ amnioinfusion %he

cesarean delivery rate was also lower in the amnioinfusion $oup imilar result were

reported by :athore and cowo&ers (2..2) !n contrast, several investi$ators were not

supportive of amnioinfusion for meconium stainin$ 8or e#ample, Usta and associates

(1;) reported that amnioinfusion was not feasible in half of women with moderate

or thic& meconium who were randomi7ed to this treatment %hese investi$ators were

unable to demonstrate any improvement in neonatal outcomes pon$ and cowo&ers

(14) also concluded that althou$h prophylactic amnioinfusion did dilute meconium,

it did not improve perinatal outcome Aast, 8raser and collea$ues (2..;) randomi7ed

amnioinfusion in 1* women with thic& meconium stainin$ of the amnionic fluid in

labor and found no benefits -ecause of these findin$s, the "mericans olle$e of


20/28

Obstetricians and 5ynecolists (2.12a,2.10c) does not recommended amnioinfusion to

dilute meconium9stained amnionic fluid "ccordin$ to Tu and cowo&ers (2..+), in

areas lac&in$ continuous monitorin$, amnioinfusion may be used to lower the

incidence of meconium aspiration syndrome

FETAL HEART RATE PATTERNS AND #RAIN DA!AGE

"ttemps to correlate fetal heart rate patterns with brain dam$e have been based

primarily on studies of infants identified as a result of medicole$al actions helan and

"hn (14) reported that amon$ 4* fetuses later found to be neurolo$ically impaired,

a persistent nonreactive fetal heart rate tracin$ was already present at the time of

admission in +. percent %hey concluded that fetal neurolo$ical in?ury occurred

predominately before arrival to the hospital When they loo&ed retrospectively at heart

rate patterns in 2. brain9dama$ed infants, they concluded that there was not a sin$le

uni@ue pattern associated with fetal neurolo$ical in?ury ("hn, 1) 5raham and

associated (2..) reviewed the world literature published between 1 and 2.. on

the effect of fetal heart rate monitorin$ to prevent perinatal brain in?ury and found no

benefit

E>PERI!ENTAL EVIDENCE

8etal heart rate patterns necessary for perinatal brain dama$e have been studied in

e#perimental animals >yers (1+2) describe the effects of complete and partial

asphy#ia omplete asphy#ia was produced by total occlusion of umbilical blood flow

that led to prolon$ed deceleration (fi$ 24901) 8etal arterial h did not drop to +.

until appro#imately *minutes after complete cessation of o#y$enation and umbilical

flow "t least 1. minutes of such prolon$ed deceleration was re@uired before these

was evidence of brain dama$e in survivin$ fetuses

>yers (1+2) also produced partial asphy#ia in rhesus mon&eys by impedin$

maternal aortic blood flow %his resulted in late decelerations due to uterine and

placental hypoperfusion /e observed that several hours of these late decelerations did

not dama$e the fetal brain unless the h fell bellow +. !nded, "damsons and >yers

(1++) reported subse@uently that late decelerations were a mar&er of partial asphy#ia

lon$ before brain dama$e occurred

%he most common fetal heart rate pattern durin$ laborNdue to umbilical cord


21/28


22/28

electronic monitorin$ were bein$ voiced from the Office O8 %echnolo$y "ssesment,

the United tates on$ress, and the enters for isease ontrol and revention

-anta and %hac&er (2..2) reviewed 2; years of the controversy on the benefits, or

lac& thereof, of electronic fetal monitorin$ Usin$ the ochrane atabase, "lfirevic

and collea$ues (2.10) reviewed 10 randomi7ed trials involvin$ more than 0+,...

women %hey concluded that electronic fetal monitorin$ in increased the rate of

cesarean and operative va$inal deliveries but produced no declines in rates of

perinatal mortality, neonatal, sei7ures, or cerebral palsy 5rimes and eipert (2.1.)

wrote a urrent ommentary on electronic fetal monitorin$ in Obstetrics and

5ynecolo$y %hey summari7ed that such monitorin$, althou$ht it has been used in *;

percent of the almost 4 million annual births in the United tates, has failed as a

public health screenin$ pro$ram %hey noted that the positive predictive value of

electronic fetal monitorin$ for fetal death in labor or cerebral palsy is near 7eroN

meanin$ that Balmost every positive test result is wron$C

%here have been two recent attempts to study the epidemiolo$ical effect of fetal

monitorin$ in the United tates, each usin$ national vital statistics of births lin&ed to

infant deaths hen and cowo&ers (2.11) used 2..4 data on 1,+02,211 sin$leton live

births, * percent of which underwent electronic fetal monitorin$ %hey reported that

monitorin$ increased operative delivery rates but decrease early neonatal mortality

rates %his benefits was $estational a$e dependent, however, and the hi$hest impact

was seen in peterm fetuses >ost recently, "nanth and collea$ues (2.10) reported a

similar but lar$er epidemiolo$ical study usin$ United tates birth certificate data

lin&ed with infant death certificate %hey studied ;+,*0,2; nonanomalous sin$leton

livebirths born between 1. and 2..4 %he temporal increase in fetal monitorin$ use

between 1. and 2..4 was associated with a decline in neonatal mortality rates,

especially in peterm $estations !n an accompanyin$ editorial, :esni& (2.10)

cautioned that an eoidemiolo$ical association between fetal monitorin$ and reduced

neonatal death does not establish causation /e su$$ested that the limitations of the

study by "nanth Bshould ma&e the reader s&eptical of the findin$sC /e opined that

the electronical fetal monitorin$ debate Boes on and on and onC "nd it does

indeed

PAR?LAND HOSPITAL E>PERIENCE4 SELECTIVE VERSUS UNIVERSAL


23/28

!ONITORING

!n ?uly 1*2, an investi$ation be$an at ar&land /ospital to ascertain whether all

women in labor should under$o electronic monitorin$ (Aevono, 1*) !n alternatin$

months, universal electronic monitorin$ was rotated with selective heart rate mo

nitorin$, which was the prevailin$ practice urin$ the 0 years investi$ation, 1+, 41.

labor were mana$ed usin$ universal electronic monitorin$, and these outcomes were

compared with a similar9si7ed cohort of women selectively monitored electronically

'o si$nificant differences were found in any perinatal outcomes %here was a small

but si$nificant increase in the cesarean delivery rate for fetal distress associated with

universal monitorin$ %hus increase application of electronic monitorin$ at par&lamd

hospital did not improve perinatal results, but it sli$htly increased the fre@uency of

cesarean delivery for fetal distress

CURRENT RECO!!ENDATIONS

%he methods most commonly used for intrapartum fetal heart monitorin$ include

auscultation with a fetal stethoscope or a oppler ultrasound device, or continuous

electronic monitorin$ of the heart and uterine contractions 'o scientific evidence has

identified the most effective method, includin$ the fre@uency or duration of fetal

surveillance that ensures optimum result ummari7ed in %able 249; are the

recommendations of the "merica "cademy of ediatrics and the "merican olle$e of

obstetricians and 5ynecolo$ists (2.12) !ntermittent auscultation or continuous

electronic monitorin$ is considered an acceptable method of intrapartum surveillance

in both low9 and hi$h9 ris& pre$nancies %he recommended interval between chec&in$

the heart rate, however, is lon$er in the uncomplicated pre$nancy When auscultation

and for . seconds !t also recommended that a 19to1 nurse9patient ratio be used if

auscultation is employed %he position ta&en by the "merican olle$e of

Obstetricians and 5ynecolo$ists (2.10b) in their ractice -ulletin, however, is

somewhat different While ac&nowled$in$ that the available data do not show a clear

benefit for the use of electronic monitorin$ over intermittent auscultation, the

commite recommends limitin$ use of auscultation to low ris& pre$nancies and further

recommends recordin$ the fetal heart rate every 1; minutes in active first sta$e labor

and every ; minutes in the second sta$e

S+r2e.a/*e L9 r.,: pre0/a/*.e, H.0h r.,: pre0/a/*.e,


24/28

A**eptae eth5,

!ntermitten auscultation

ontinuous electronic

monitorin$ (internal or

e#ternal)

Hes

Hes

Hes a

Hes b

E2a+at./ ./ter2a,

8irst9sta$e labor (active)

econd9sta$e labor

0. min

1; min

1; min a,b

; min a,c

a9 predurin$, ferably before, and after a uterine contraction

b9 includes tracin$ evaluation and chartin$ at least every 1; min

c9 tracin$ should be evaluated at least every ; min

form the "merican "cademy of ediatrics and the "merican olla$e of Obtetricians

and $ynecolo$ist, 2.12

INTRAPARTU! SURVEILLANCE OF UTERINE ACTIVIT

"nalysis of electronically measured uterine activity permits some $eneralities

concernin$ the relationship of certain contraction patterns to labor outcome %here is

considerable normal variation, however, and caution must be e#ercised before ?ud$in$

true labor or its absence solely from a monitor tracin$ Uterine muscle effiociency to

effect delivery varies $reatly %o use an analo$y, 1..9meter sprinters all have the same

muscle $roups yet cross the finish line at different times

INTERNAL UTERINE PRESSURE !ONITORING

"mniotic fluid pressure is measured between and durin$ contraction by a fluid K

filled plastic catheter with its distal tiplocated above the presentin$ part (8i$24902)

%he chateter is connected to a strain K $au$e pressure sensor ad?usted to the same

level as the chateter tip in uterus %he amplified electrical si$nal produced in the strain

$au$e by variation in pressure within the fluid system is recored on a calibrated

movin$ paper strip simultaneously with the fetal heart rate recordin$ ( see fi$249)

!ntrauterine pressure chateters are now avaible that have the pressure sensor in the

chatete tip, which obviates the need for the fluid column

E>TERNAL !ONITORING

Uterine contraction can be measured by a displacement transducer in which the


25/28

transducer button, or J Bplun$erC, is held a$ainst the abdominal wall "s the uterus

contracts, the button moves in proportion to the stren$th of the contraction %his

movement is convered into a measurable electrical si$nal that indicated the relative

intensity of the contraction !t has $enerally been accepted to not $ive an accurate

measure of intensity -a&&er and associates (2.1.) performed a randomi7ed trial

comparin$ internal versus e#ternal monitorin$ of uterine contractions in 14; women

%he two methods were e@uivalent in terms of operative deliveries and neonatal

outcomes

PATTERNS OF UTERINE ACTIVIT

aldeyro9barcia and oseiro (1.), from >ontevideo, Uru$uay, were pioneers

who have done much to elucidate the pattern of spontaneous uterine activity

throu$hout pre$nancy ontractile waves of uterine activity werw usually measured

usin$ intraamniotic pressure catheters -ut early in their studies, as many four

simultaneous intramiometrial microballons were also used to record uterine pressure

%hese investi$ators also introduced the concept of >ontevideo units to define uterine

activity (hap 20,pJ 4;*) -y this definition, uterine performance is the product of the

intensity K increased uterine pressure above baseline tone of a contraction in mm/$

multiplied by contraction fre@uency per 1. minutes 8or e#ample, three contractions

in 1. minutes, each of ;. nn /$ intensity, would e@ual 1;. >ontevideo units

urin$ the first 0. wee&s of pre$nancy,uterine activity is comparatively

@uiescent ontraction are seldom $reater than 2. mm /$ "nd these have been

e@uated with those first described in 1*+2 by Gohn -ra#ton /ic&s Uterine activity

increase $radually after 0. wee&s, and it is noteworthy that these -ra#ton /ic&s

ontractions also increase in intensity and fre@uency 8urther increases in uterine

activity are typical of the last wee&s of pre$nancy, termed prelabor urin$ this phase

%he cervi# ripens (hap21J41.)

"ccordin$ %o aldeyro K -arcia and oseiro (1.), clinical labor usually

commences when uterine activity reaches values between *. ande 12. >ontevideo

units %his translates into appro#imately three contractions of 4. mm /$ every 1.

minutes !mportantly, there is not clear K cut division between prelabor and labor, but

rather a $radual and pro$ressive transition

urin$ first9sta$e labor, uterine contarctions increase pro$ressively in intensity

from appro#imately 2; mm /$ at commencement of labor to ;. mm /$ at the end Et


26/28

the same time, fre@uency increases from there to five contractions per 1. minutes, and

uterine baseline tone from * to 2. mm /$ Uterine activity further increases durin$

second K sta$e labor, aided by maternal pushin$ !ndeed, contractions .f *. to 1..

mm/$ are typical and occur as fre@uently as five to si# per 1. minutes !nterestin$ly,

the duration of uterine contractions K . to *. second K does not increase appreciably

from early active labor throu$h the second sta$e (-a&&er,2..+J ontonnier,1+;)

resumably, this duration constanly serves fetal repiratory $as e#chan$e urin$ a

uterine contarctions, as the intrauterine pressure e#ceeds that of the intervillous space,

respiratory $as e#chan$e is halted %his leads to functional fetal Jbreath holdin$C

Which has a . K to *. K second limit that remains relatively constant

aldeyro K -arcia and oseiro (1.) also observed empirically that uterine

contarctions are clinically palpable only after their intensity e#ceeds 1. mm /$

>oreover, until the intensity of contarctions reaches 4. mm /$, the uterine wall can

readily be depressed by the fin$er "t $reater intensity, the uterine wall then becomes

so hard that is resist easy depression Uterine contarctions usually are not associated

with pain until their intensity e#ceeds 1; mm /$, presumably because this is the

minimum pressure re@uired for distendin$ the lower uterine se$ment and servi&s !t

follows that -ra#ton /ic&s contractions e#ceedin$ 1; mm /$ may be perceived as

uncomfortable because distension of the uterus, cervi#, and birth canal is $enerally

thou$ht to produce discomfort

/endric&s (1*) observed that Bthe clinican ma&es $reat demands upon the

uterusC %he uterus is e#pected to remain well rela#ed durin$ pre$nancy, to contract

effectively but intermittently durin$ labor, and then to remain in a state of almost

constant contaction for severa hours postpartum 8i$ure 24 K 00 demonstates an

e#ample of normal uterine activity durin$ labor Uterine activity pro$ressively and

$radually increases from prelabor throu$h late labor !nterestin$ly, as shown in 8i$ure

24 K 00, uterine contraction after birth are identical to those resultin$ in delivery of

the infant !t is there identical to those resultin$ in delivery of the infant !t is therefore

not suprisin$ that the uterus that performs poorly before delivery is also prone to

atony and puerperal hemorrha$e

ORIGIN AND PROPAGATION OF CONTACTIONS

%he uterus has not been studied e#tensively in term of its nonhormonal


27/28

physiolo$ical mechanisms of function %he normal contractile wave of labor

ori$inates near the uterine and of one of the fallopian tubes %hus, these areas act as

Bpacema&ersC (8i$20904) %he ri$ht pacema&er usually predominates over the left

and starts most contractile waves ontractions spreds from the pacema&er area

throu$htout the uterus at 2 cmFsec, depolari7in$ the whole or$an within 1; seconds

%his depolari7in$ wave propa$ates downward toward the cervi& !ntensity is $reatest

in the fundus, and it diminishes in the lower uterus %his phenomenon is thou$ht to

reflect reductions in myometrial thic&ness from to the cervi# resumably, this

descendin$ $radient of pressure serves to direct fetal descent toward the cervi# and to

efface the cervi# !mportantly, all parts of the uterus are synchroni7ed and reach their

pea& pressure almost simultaneously, $ivin$ rise to the curvilinear waveform shown

in 8i$ure 24904 Houn$ and Phan$ (2..4) have shown that the initiation of each

contarctions is tri$$ered by a tissue9level bioelectric event

%he pacema&er theory also serves to e#plain the varyin$ intensity of ad?acent

coupled contarctions shown in panels " and - of 8i$ure 24900 uch couplin$ was

termed incoordination by aldeyro K -arcia and oseiro (1.) " contractile wave

be$ins in one corneal K re$ion pacema&er, but does not synchronously depolari7e the

entire uterus "s a result, another contraction be$ins in the contralateral pacema&er

and produces the second contractile wave of the couplet %hese small contactions

alternatin$ with lar$er ones appear to be typical of early labor !ndeed, labor may

pro$ress with such uterine activity, albeit at a slower pace %hese authors also

observed that labor would pro$ress slowly if re$ular contractions were hypotonic K

that is, contarctions with intensity less than 2; mm /$ or fre@uenly less than 2 per 1.

minutes

/auth and cowor&ers (1*) @uantified uterine contraction pressures in 1.

women at term who received o#ytocin for labor induction or au$mentation >ost of

these women achieved 2.. to effect delivery %he authors su$$ested that these levels

of uterine activity should be sou$ht before consideration of cesarean delivelry for

presumed dystocia

NE" TER!INOLOG FOR UTERINE CONTRACTIONS

%his has been recommended by the "merican olle$e of Obstetricians and


28/28

5ynecolo$ists (2.10b), for the description and @uantification of uterine contarctions

'ormal uterine activity is defined as five or fewer contactions in 1. minutes, avera$e

over a 0. K minutes window Tachysystole was defined as more than five contarctions

in 1. minutes, avera$ed over 0. minutes %achysystole can be applied to spontaneous

or induced labor (hap2,p;2+) the term hyperstimulation was a abandoned

tewart and associates (2.12) prospectively studied uterine tachysystole in ;*4

women under$oin$ labor induction with misoprostol at ar&land /ospital %here was

no association of adverse infant outcomes with increasin$ number of contarctions per

1. minutes or per 0. minutes i# or more contractions in 1. minutes, however, werw

si$nificantly associated with fetal heart rate decelerations

CO!PLICALTIONS OF ELECTRONIC FETAL !ONITORING

Electrodes for fetal heart rate evaluation and catheters for uterine contraction

measurement are both associated with infre@uent but potentially serious

complications :arely, an intrauterine pressure catheter durin$ placement may lacerate

a fetal vessel in the placenta "lso with insertion, placental and possibly uterine

perforation can cause hemorrha$e, serious morbidity, and spurious recordin$s that

have resulted in inappropriate mana$ement evere cord compression has been

described from entan$lement with the pressure catheter !n?ury to the fetal scalp or

breech by a heart rate electrode is rarely severe /owever, application at some other

site K such as the eye in face presentations K can be serious

-oth the fetus and the mother may be at increased ris& of infection from internal

monitorin$ (8aro, 1.) calp wounds from the electrode may become infected, and

subse@uent cranial osteomyelitis has been reported (-roo&, 2..;6 E$$in&s, 2..46

>c5re$or, 1*) the "merican olle$e of Obstetricians and 5ynecolo$ists (2.12)

have recommended that certain maternal infections, includin$ human

immunodeficiency virus (/!3), herpes simple# virus, and hepatitis - and virus, are

relative contraindications to internal fetal monitorin$

Ruptur Uteri Dan Fetal Distress

Documents