Abnormal labor
(Dr Haider Al Shamma'a)
Learning outcome :To know the risks of abnormal labor
To know the types of abnormal labor
To know how to diagnose and how to treat these abnormalities
To know how to prevent or reduce complications
To know how to reduce maternal and fetal morbidity and mortality
Malposition & malpresentation of the head
This include
1 – occipito-posterior & deep transverse arrest
2 – face presentation
3 – brow presentation
Malposition and malpresentation carry an increased morbidity and mortality to the fetus and to the mother
specially if labor is attended by inexperienced personnel
Maternal risks
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Prolonged labor
Infection of the genital tract
Obstructed labor
Intrapartum hemorrhage
Post partum hemorrhage
Lacerations of the genital tract and perineum
Risks of anesthesia
DVT & pulmonary embolism
Vesico vaginal fistula
Fetal risks
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Cord prolaps
Hypoxia
Infection
Traumatic injuries
Meconium aspiration
Occipito-posterior position
the denominator is the occiput , which occupy the posterior part of the maternal pelvis
causes:
1. Anterior placenta
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Anthropoid pelvis
Android pelvis
Gross pendulous abdomencongenital malformation of the fetus
Extensor tone
Polyhydramnious
Prematurity
Multiple pregnancy
Leiomyoma of the uterus
Chance
Diagnosis of occiput posterior
On abdominal exam:
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Flattening of the lower abdomen below the umbilicus
Easily felt fetal limbs anteriorly
Difficult to feel the fetal back
The head is not engaged
Fetal heart heard at the flanks
0n pelvic exam:
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High presenting part
Bulging sausage shaped membranes
Early rupture of membranes ( less than 3 cm cervical dilatation )
Anterior fontanelle near pubic symphysis
Difficult to feel the posterior fontanelle
The ear directed posteriorly
Mechanism of labor
Engagement occur in oblique diameter with the occiput in the right occiputo posterior position ROP ( 3times
more than left occipito posterior LOP )
Engaging diameter is is the suboccipito frontal diameter of 10.5 cm if the head is well flexed . or the occipito frontal
of 11.5 cm if the head is deflexed . both are larger than the suboccipito bregmatic of 9.5 cm in case of occipito
anterior position
These diameters give an oval shaped presenting part which can not fit well on the cervix
With further descent the occiput will touch the pelvic floor first and will be rotated anteriorly through 3/8th of a
circle 135˚ ie long rotationthe occiput become anterior and the mechanism of labor will be tha same as in occipito
anterior position , this occur in about 70% of cases
In 10% of cases the head is deflexed and the sinciput will touch the pelvic floor first and the sinciput will be rotated
anteriorly which means the occiput will be rotated posterior by 1/8th of a circle 45˚ short rotation to give a direct
occipito posterior DOP . the mechanism of labor become different with further descent the head will deliver by a
combination of flexion and then extention at the outlet , the emerging diameter is the occipito frontal diameter of
11.5 cm which cause great distention of the vulva and perineum causing perineal tears
In 20% of cases rotation arrested at lateral position ROL and the mechanism of labor stops ,causing obstructed
labor . this needs assisted delivery
Features of labor in occipito posterior
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Slow progress
Backache is severe
Incoordinate uterine contraction is common
Increased incidence of premature rupture of membranes
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Increased incidence of cord prolaps
Increased incidence of perennial lacerations
Excessive molding may cause tentorial tears
Treatment
Before labor no attempt for correction should be done
During first stage
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Correction can not be done
Observation of ut cont. , cx. Dilat. , descent of the head ,fetal heart rate regularity using continuous fetal
monitoring and tachometer and plot the results on partogram
Nothing by mouth ( due to increased risks of operative delivery and the need of GA
Iv fluid 125 ml / hr of 1/5th glucose saline
Oxytocin infusion to treat irregular uterine contractions if present **
Analgesia best is epidural analgesia ** or pethidin 100 mg im
( ** very important part of treatment)
cesarean section is indicated in the following situations:
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If no progress on 2 different examinations
Maternal distress
Fetal distress
During second stage
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A mistake in diagnosis of 2nd stage is not uncommon as involuntary bearing down can occur before full Cx
dilatation due to pressure of larger occiput on the rectum and the sacral plexus
Pv exam is important to Dx full Cx dilatation before encourage the patient to push
Assess the degree of deflexion of the head
Assess the degree of molding
Assess the degree of caput succedaneum
If the head deflexed ,excessive molding and caput then spontaneous labor may not occur and the patient
need assisted delivery
Assisted delivery is indicated in the followings
delay of the second stage
deep transverse arrest
Fetal distress
Maternal distress
Assisted delivery
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cesarean section
manual rotation + forceps traction
forceps rotation and traction (Kielland's forceps)
vacuum traction (Ventouse vacuum extractor)
cesarean ection:indicated in the following
1. fetal ditress in first stage
2. OP + abnormal pelvis
3. Cord prolaps
There is a tendency of more cesarean section than traumatic vaginal delivery specially in developed countries
Manual rotation
Correction of OP by using the fingers and try to rotate the head to OA and then pull the head by forceps
Disadvantages :
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Need anesthesia
The hand take additional pace
May cause trauma
Pulling by the hand is not feasible and need to use forceps
Kiellands' rotation traction
It is a special type of forceps with a light construction deigned to permit rotation of fetal head. It is very useful BUT
dangerous in the hands of inexperienced person, it may cause severe vaginal lacerations and fetal damage
Ventouse vacuum extractor
It is composed of a metal or plastic cup connected by tube system to a vacuum pump , the cup applied to the fetel
scalp and fixed by –ve pressure (vacuum) and then can pull the fetus by its scalp
Advantages
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Can be applied without GA
Not take extra space
Easier to use
Can be used before full Cx dilatation
Face presentation
Occur when the head I fully extended, it occur in 1/300 deliveries
Causes
As in OP
Mechanism of labor
The denominator is the chin (mentum)
Mento posterior position -------no mechanism of labor as the engaging diameter is the sterno bregmatic of 16 -18
cm becaue the chest and the head try to pass the brim at the same time
Mento-anterior position engagement occur in the transverse or oblique diameter of the inlet descent occur late in
the second stage engagement only occur at +3 station (compared to zero station in vertex presentation)
Due to the oblique line of thrust the econd tage will be more prolonged than usual , internal rotation will bring the
chin anterior , the face deliver by flexion the emerging diameter is the submento vertical of 11cm causing
considerable stretching of the vulva and perineum
The rest of the body deliver by the usual mechanism
Diagnosis
On abdominal exam finding
Longitudinal lie ,cephalic presentation , groove can be felt between the head and the back,the head is not engaged
On vaginal exam feeln the chin , soft cheeks ,mouth , nose , cheek bone and orbital ridge
management
exclude congenital malformation, contracted pelvis, exclude other risks factors like age , parity ,previous
obstetrical history , preeclampsia . estimate fetal weight if > 3.5 kg then cesarean section is considered
if cesarean section wa not indicated
manage the first stage as high risk labor ( as in Occiput Posterior mentioned above )
rarely may use forceps to deliver face presentation
vacuum extractor Is contraindicated .
Brow presentation
Occur in 1/1000 delivery when there is incomplete extension of the head and it is usually a transient presentation
and change to face presentation if extension become complete , or change to vertex if flexion occur
Causes
Same as face presentation
Diagnosis
on abdominal exam as in face presentation but the groove at the neck is less prominent
on vaginal exam feel nose , orbital ridge , brow , anterior fontanelle . but can not feel the chin
mechanism of labor
engaging diameter is the mentovertical diameter of 14cm no mech. Of labpor
management
usually convert to face or vertex if brow persist for more than 2 hrs then cesarean section is indicated
References
1. Obstetrics illustrated
2. Obstetrics by Ten teachers
3. William 's obstetrics