Abnormalities Of The Passenger

Abnormalities of the Passenger Liu Yuling

M.D. Department Of Obstetrics & Gynecology Renmin Hospital Wuhan University

Abnormalities of the Passenger  Be

known as fetal dystocia

 That

is that are caused by abnormalities of the fetus.

 Common

fetal abnormalities leading to dystocia include  Excessive

fetal size  Malposition  Congenital anomalies  Multiple gestation



Malposition and Malpresentation 

Vertex malpositions  

    

 

Occiput posterior Occiput transverse

brow presentation Face presentation Abnormal fetal lie Breech presentation Compound presentation

Fetal Macrosomia Fetal Malformation

Occiput posterior

occiput posterior position  It

may be normal in early labor, with about 10-20% of fetuses in occiput posterior position at onset of labor.

 In

87% of cases, the head rotates to the occiput anterior position when it reaches the pelvic floor

 If

the head does not rotate ( about 510% of cases ), persistent occiput anterior position may result in dystocia.  Approximately two-thirds of cases of occiput posterior presentation at delivery occur through malrotation during the active phase of labor.

Mechanism  The

mechanism of this fetopelvic disproportion is partial deflexion of the fetal head  This partial deflexion increases the diameter that must engage in the pelvis

Causative factors A

contracted pelvis

 Anthropoid

pelvis  Android pelvis  Insufficient

uterine action  Epidural anesthesia  Oxytocin augmentation

Diagnosis  Manual  The

vaginal examination

diagnosis is generally made by manual vaginal examination of the orientation of the fetal cephalic sutures.  It may by confirmed by palpating the configuration of the fetal ear

Treatment  Infusing  Clinical

of oxytocin

pelvimetry should be attempted  If no gross pelvic contraction is documented and uterine contractions are inadequate, cautious infusion of oxytocin may be tried

The modes of delivery  Depending

on the clinical findings, the following modes of delivery are available: Spontaneous vaginal delivery  Outlet forceps delivery of a direct occipital posterior presentation  Manual rotation to the occipital anterior position, followed by spontaneous or out forceps delivery  Misfire rotation and extraction  Vacuum extraction for rotation, extraction, or both  Cesarean section 

Occiput directly posterior. Low forceps (Simpson) delivery as an occiput posterior. (O= occiput, S = symphysis.)

PERSISTENT OCCIPUIT POSTERIOR POSITION 

Manual rotation Manual rotation to the occipital anterior position followed by spontaneous or out forceps delivery

Prognosis  The

infant The prognosis of the infant is excellent when macrosomia and gross fetopelvic disproportion have been excluded, other criteria for forceps delivery have been met, and the operator is sufficiently skilled

Maternal morbidity  Maternal

morbidity It occurs more frequently in occipital posterior deliveries

 Extension

of episiotomies  Higher rates of anal sphincter injury  Other birth canal lacerations

Occiput transverse

Occiput transverse  It

(like occiput posterior) is frequently a transient position, and in most labor the fetal head spontaneously rotates to the occiput anterior position

LOT(left occipito-transverse)

ROT(right occipito-transverse)

Persistent Occiput transverse It is frequently associated with  Pelvic

dystocia

 Platypelloid

pelvis  Android pelvis  Uterine

dystocia

 Diagnosis,

management and prognosis are similar to those of persistent occiput posterior presentation  When the fetal head engages but for various reasons does not rotate spontaneously in the midpelvis as in normal labor, midpelvic transverse arrest is diagnosed.

Deep transverse arrest  Occasionally

occurs at the inlet  Molding and caput succedaneum formation falsely indicating a lower descent  Cesarean section is required

Brow presentation

Brow Presentation  Brow

presentation usually is transient fetal presentations with various degrees of deflexion of the fetal head  During the normal course of labor, conversion to face or vertex presentation generally occurs  If no conversion takes place, dystocia is likely

The attitude of fetuses’ head occiput bregma brow presentation presentation persentation

★

flex

Not flex Not extention

deflextion

12

9.5 13.5 •The anteroposterior diameter of the deflexed fetal head exceeds the average 9.5 cm of the suboccipitobrematic diameter in vertex presentation. •The average value for the occipitofrontal diameter in the sinciput position is 12 cm for the occipitomental diameter in the brow position, 13.5 cm.

presentation

The average value

vertex presentation

suboccipitobrematic diameter

9.5 cm

sinciput position bregma presentation

occipitofrontal diameter

12 cm

brow position

occipitomental diameter

13.5 cm

 Causative

factors Be associated with the same causative factors as face presentation.  Associated findings In approximately 60% of cases, pelvic contraction, prematurity, and grand multiparity are associated findings.  Diagnosis The diagnosis is made by vaginal examination

Management 

Initial management is expectant 



Spontaneous conversion to vertex presentation occur in more than one – third of all brow presentations.

Arrest patterns and uterine inertia are common sequelae because pelvic contraction is so often associated with this presentation.

Oxytocin is not recommended  Continuous electronic fetal monitoring is necessary  Liberal use of cesarean section should be made for delivery in cases complicated by a poor outlook for labor 

Prognosis  Perinatal

mortality rates are low when corrected for congenital anomaly, prematurity, and manipulative vaginal delivery

Face presentation

Definition  The

fetal head is fully deflexed from the longitudinal axis  This presentation occurs in about 0.2% of all deliveries

The attitude of fetuses’ head

occiput presentation

bregma presentation

brow persentation

face persentation

★

flex

Not flex Not extention

deflextion

extension

12

9.5 13.5 •The anteroposterior diameter of the deflexed fetal head exceeds the average 9.5 cm of the suboccipitobrematic diameter in vertex presentation. •The submentobregmatic diameter is only slightly larger than the 9.5 cm suboccipitobregmatic diameter

Fetal position in face presentation

Symphyasis pubis

sacrum Fetal position in face presentation is determined by using the mentum as the fetal point of reference to the maternal pelvis.

Causative factors  Congenital

malformations (particularly anencephaly)  Cephalopelvic disproportion  Prematurity  Grand multiparity

Diagnosis  The

fourth maneuver of Leopold  Vaginal examination  ultrasonography

The fourth maneuver of Leopold

Vaginal examination

Differential Diagnosis Breech presentation  Face presentation may be distinguished from breech presentation by identification of the mouth and both malar eminences in triangular configuration

Mechanism

The mechanism of labor in these cases consists of the cardinal movements of descent, internal rotation, and flexion, and the accessory movements of extension and external rotation.

Prognosis & Treatment  The

prognosis for vaginal delivery is guarded for face presentation  The submentobregmatic diameter is only slightly larger than the 9.5 cm suboccipitobregmatic diameter, but complications generally arise with simultaneously occurring pelvic contraction or a persistent mentum posterior position

Mentum posterior positions  Mentum

posterior positions in averagesize fetuses are not deliverable vaginally as they are unable to extend

A persistent mentum posterior position

Face presentation. The occiput is the longer end of the head lever. The chin is directly posterior. Vaginal delivery is impossible unless the chin rotates anteriorly. At the same time, the skull undergoes considerable molding, manifested by an increase in length of the occipitomental diameter of the head

Mentum posterior positions  Arrested

labor is typical when spontaneous rotation to the mentum anterior position fails to occur  There is little or no place for manual flexion of the fetal head or manual rotation from the mentum posterior position to the mentum anterior position

Mentum anterior positions  Oxytocin

augmentation

With mentum anterior positions, oxytocin augmentation may be used for arrested labor if cephalopelvic disproportion can be ruled out  Delivery

may be accomplished by

Spontaneous vaginal delivery  Use of low forceps to rotate to the mentum anterior position  Cesarean section for arrested labor 

FACE PRESENTATION

Edema in face presentation Edema may sometimes significantly distort the face.

Abnormal fetal lie

Definition 

In transverse or oblique lie, the long axis of the fetus is perpendicular to or at an angle to the maternal longitudinal axis.

TRANSVERSE LIE  When

the long axis of the fetus is approximately perpendicular to that of the mother

:obligue lie, unstable lie :shoulder-over the pelvic inlet head-in one iliac fossa breech-in the other iliac fossa

 Abnormalities  occur

in axial lie

overall in about 0.33% of all deliveries  occur 6 times more frequently than normally in premature labors

Causative factor  Grand

multiparity Unusual relaxion of the abdominal wall resulting from high parity  Prematurity  Pelvic contraction  Abnormal placental implantation Placenta previa  Excessive

amnionic fluid

TRANSVERSE LIE  Diagnosis 

Inspection 



wide abdomen Ut fundus extends to only slightly above umbilicus

Palpation (Leopold’s maneuvers ) 



no fetal pole in the fundus ballottable head in one iliac fossa breech in the other back  



anterior-> (hard resistance plane) posterior-> irregular nodulations representing small parts

Be confirmed by real-time ultrasound scanning

TRANSVERSE LIE  vaginal

examination

 the

side of the thorax  further dilatation: scapula or clavicle  axilla: shouler direction  later

in labor  shoulder become tightly wedged in the pelvis  a hand and arm frequently prolapse

TRANSVERSE LIE  Course

of labor spontaneous delivery of a fully developed infants is impossible with a persistent transverse lie

TRANSVERSE LIE 

After ROM, labor continue fetal shoulder is forced into the pelvis, the corresponding arm frequently prolapse



After some descent shoulder is arrested in pelvis, with the head is in the one iliac fossa and breech in the other







As labor continues  the shoulder is impacted firmly in the upper part of the pelvis  contracts vigorously After a time  a retraction ring rises increasingly higher if not promptly managed  uterine rupture  mother & fetus die

conduplicato corpore if small fetus(<800g), large pelvis in spontaneous delivery ->the head and thorax pass through the pelvic cavity at the same time

TRANSVERSE LIE Prognosis :maternal risk, fetal hazard: increased :even with the best care, morbidity is incereased ->placenta previa, cord prolapse

Treatment  External

cephalic version

conversion to a longitudinal lie (before or early labor)  with the membrane intact, no indication of cesarean delivery  Only after 39 weeks because of spontaneous conversion to a longitudinal lie  next several contraction: fix the head in the pelvis (during the early labor)

 Prompt  the

low vertical cesarean delivery

onset of active labor  cesarean-vertical incision difficulty in extraction of the fetus (not foot or head on incision site)

Compound presentation

Compound presentation A prolapsed extremity alongside the presenting part constitutes compound presentation.

 Compound

presentation complicates about 0.1% of deliveries  Prematurity and a large pelvic inlet are associated clinical findings

Diagnosis  Physical

examination

 Compound

presentations are often diagnosed during physical examination and investigation for failure  Most commonly, a hand is palpated beside the vertex

 Vaginal

delivery

 Labor

in most of these patients will end in uncomplicated vaginal delivery

 Cesarean

section

 Cesarean

section should be done in the presence of dystocia or cord prolapse

 Attempts

to reposition the fetal extremity are discouraged, except for gentle pinching of the digits to determine whether the fetus will retract the extremity.

Fetal Macrosomia

Definition  Excessive

fetal size

 LGA

implies a birth weight greater than the 90th percentile  Macrosomia implies growth beyond a certain size, usually 4000-4500 g, regardless of gestational age  It

occurs in about 5% of delivery

Risk factors Associated risk factors  maternal diabetes  maternal obesity (>70kg)  excessive maternal weight gain (>20kg)  postdate pregnancy  previous delivery of a macrosomic infant However, less than 40% of macrosomic infants are born to patients with identifiable risk factors.

Diagnosis  Abdominal 

palpation

Diagnosis by abdominal palpation is notoriously inaccurate

 Parameters

from ultrasound

A better estimated weight may be possible with ultrasonography and standard measured parameters  Ultrasound also lacks accuracy, particularly with increased fetal size 

Estimated weight of fetus (FW) Fundal size (FS) Abdomen circumference (AC)

Maternal

FW = FS(cm) × AC(cm) ± 250g FS(cm) ＋ AC(cm) ≥ 140(cm)

80% ≥ 4000g (cm)

FS(cm) ＋ AC(cm) ≥ 135 (cm) Fetal Macrosomia BPD ＋ FL ≥ 17 (cm) is possible

Estimated weight of fetus (FW) Ultrasound BPD≥8.7cm FL≥6.9cm

FW ＞ 2500g

BPD≥9.6cm FL≥7.6cm

80% FW ＞ 3500g

FW= BPD(cm) × 900 - 5200g Error±250g

Prognosis  Perinatal

mortality  Shoulder dystocia While morbidities to infant and mother increase with increasing size between 4000 and 4500 g, perinatal mortality for fetuses weighting more than 4500 g is about fivefold higher than in normal term infants, and incidence of shoulder dystocia is at least 10% in this group.

SHOULDER DYSTOCIA Incidence :varies depending on the criteria used for diagnosis :0.9%ture shouder dystocia-0.2% (1987) :maneuvers were required so, current report-0.6~1.4% #increasing factor(1960-1980) :increasing birthweight :shoulder-to-head, chest-to head disproportions :increased attention



SHOULDER DYSTOCIA 

Use of maneuvers – define shoulder dystocia :but, use of one or more maneuvers-NO diagnosis :TIME INTERVAL (head to body) -normal: 24 seconds -shoulder dystocia: 79seconds  exceeding 60 seconds: define shoulder dystocia

SHOULDER DYSTOCIA 

Shoulder dystocia drill 1.call for help 2.generous episiotomy 3.suprapubic pressure -simple, only one assistant -while normal downward traction 4.McRoverts maneuver -two assistants -resolve most case -if fail, next steps may be attempted

SHOULDER DYSTOCIA 5. the Woods screw maneuver 6. posterior arm delivery is attempted 7. other technique -Zavanelli maneuver -fracture of ant. clavicle, humerus

Fetal Malformation

 Fetal

malformation may cause dystocia, primarily through fetopelvic disproportion

Fetal anomalies  hydrocephalus  with

an incidence of 0.05%

 enlargement  distended

of the fetal abdomen

bladder  ascitesabdominal neoplasms  other fetal masses  Meningomyelocele  cystosarcoma.

Fetal abdominal dystocia at 28 weeks caused by immensely distended bladder. Delivery was made possible by expression of fluid from bladder through perforation at umbilicus. Median sagittal section shows interior of bladder and compression of organs of abdominal and thoracic cavities. A black thread has been laid in the urethra. ( From Savage, 1935.)

Management Management is determined by the severity of the disorder and its prognosis.