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INTRODUCTION: -
Previous cesarean section makes a pregnancy an
instant high risk. Very close monitoring of the entire pregnancy and
more so of labor becomes mandatory. Even the academicians of our
subject have indulged in lots of debates and controversies as
regards the management of pregnancy and labor in a case of previous
cesarean section. The scar on a dynamic structure like uterus has
created this entire debate. As a student of the subject and as a
clinician it becomes necessary for us to learn about all possible
aspects related to it. This subject has been treated with a
clinical approach:
HISTORY: -
It becomes imperative to ask some vital
points regarding history to this mother. This includes number of
previous cesarean sections. It will decide as to whether a trial
of vaginal delivery can be given. If she had previous one
Cesarean Section (C.S), hospital delivery is a known rule for
previous two C.S. most believe that C.S. is absolutely
indicated. However a small minority does feel that a vaginal
trial can be given if the indications of previous both CS are
non-recurrent. These group of workers feel that three and more
C.S. only are an absolute indication for C.S.
Type of previous C.S.: Now a days, previous
lower segment C.S. is a rule and classical C.S. is an exception.
Previous classical C.S. is held against a trial for vaginal
delivery.
Timing of previous C.S.: It is believed
that uterine wounds heal better if a C.S. is done before the
onset of labor. Thus if a mother gives such a history, it
becomes a small added point in favor of a vaginal trial.
Extension of the scar: If the operative
information of previous surgery is available and indicates an
extension of the scar, or an inverted T incision, these go
against a vaginal trial, to a significant extent.
Puerperal infection: If the mother in
question gives history of puerperal sepsis, it is believed that
the strength of the scar is reduced. This has to be borne in
mind if a trial for vaginal delivery is to be given in this
obstetric performance.
Indication for previous C.S.: This is very
vital. A bony contraction of the pelvis is an obvious recurrent
indication. Mothers with such recurrent indications are
obviously a choice for cesarean section this time.
EXAMINATION :-
A short statured mother (< 145 cms. for
Indian mothers) is a high risk for repeat C.S. Cephalopelvic
Disproportion (CPD) is to be watched wisely. Failure to progress
in labor or dystocia is a leading indication for primary
cesarean section and has major impact on escalating CSR in the
USA. Recent literature indicates that the diagnosis of CPD has
no prognostic value from one pregnancy to the next and generally
should not exclude a patient from a trial of labour. Meier &
Porreco (1982) studied 230 trials of labor and found that, of
107 patients whose primary section was for CPD, 67.3% were
delivered vaginally 31% of which were larger than the one they
had by cesarean section. These authors also found that, of 83
women whose first pregnancy ended by cesarean section for CPD,
78% were delivered vaginally following trial of labor.
In patients who had a primary cesarean section
for breech presentation, 93.4% were delivered vaginally following
trial of labor. However in patients having breech presentation with
previous cesarean section scar, the consensus is that they should
have a repeat cesarean section. Paul et al examined 72 patients with
breech presentation and found that vaginal delivery was achieved in
46% of 18% allowed a trial of labor.
An anemic mother
requires extra efforts to treat her anemia because if she requires a
C.S., again, she enters labor, her anemic status be promptly
corrected. Presence of any other medical disorder which may have
occurred now like jaundice or might have missed last time, like a
heart disease, add to surgical risk and be promptly treated.
A systematic obstetric examination of the case
helps in identifying malpresentations if any .A previous C.S. with
breech, transverse lie or similar unfavorable presentations and lie
are not preferred for including a vaginal trial. For breech in
present pregnancy, it is stated that rarely but really, breech
extraction may be required. This may invite on intra uterine
manipulation. This may and increase the stress on the previous scar.
The role of External Cephalic Version was
recently addressed in a case with a previous C.S. Version attempts
were successful and women went on to have vaginal birth after
cesarean section. A total of 19 successful vaginal deliveries
occurred (50%) . Success rate of ECV was lowered when breech was the
indication of the previous cesarean section. The vaginal delivery
rate was increased after successful ECV in patients previously
vaginally delivered, but this difference did not reached
significance. No maternal or neonatal complications occurred.
It was therefore concluded in this study that ECV is acceptable
and effective in women with a prior low transverse uterine scar,
when safety criteria are observed. (Unger JB)
Presence of a fetal macrosomia in a case of
previous C.S. requires a close vigilance even if the previous
indication was non-recurrent. Presence of multiple pregnancy
with favorable presentation remains a controversial issue. Some
believe that this has no scope for vaginal delivery whereas
others feel it there is no harm if other criteria for a
favorable trial are met satisfactorily. In a retrospective study
by Gilbert et al, it was shown that a transverse low uterine
segment scar does not present a risk because of uterine
distension secondary to a twin pregnancy. Strong et al studied
the pregnancy outcome 56 women with twin gestation and a
previous section birth. In these patients 31 (55%) underwent an
elective repeat cesarean delivery and 25 (45%) attempted a
vaginal delivery. In the latter, 18 (72%) were vaginally
delivered of both infants. The dehiscence rate among women with
twin pregnancies who attempted a trial of labor was 4% compared
with 2% in women with a singleton pregnancy. The rule is to
individualize the case.
Antenatal pelvic assessment is fraught with
pit falls except if the deformity or contraction is very
distinct. It is therefore not preferred currently by many.
INVESTIGATIONS :-
A routine blood count to rule out anemia,
infection and bleeding profile is helpful.
USG is obviously the most important
investigative tool. Besides its routine use for any pregnant mother
in a case of previous C.S., it is required to localize the placenta.
A low-lying placenta on or adjacent to the scar is an important
finding of clinical bearing. It will guide one to allow a vaginal
delivery or otherwise. It will also make the obstetrician aware of
the difficulty he many encounter while doing a C.S. A congenitally
malformed fetus is a grave risk. This should be carefully looked for
and if found to be present and if the malformation is major,
termination is the obvious choice. It is sad to caesar out a baby
for failure to progress in a case of previous C.S. and the baby is
found to be hydrocephalic, causing this non-progression. The other,
aspects revealed by USG are as in any other case as well. These are
not repeated for reasons of brevity and relevance.
X-ray pelvimetry has a dying role in modern
obstetrics even, in cases of previous C.S. Clinical pelvimetry is
any day preferred as dynamic, judges the interplay of maternal
passages and the fetus and more accurate. Digital C.T. scan is
mentioned to be superior but not popular due to the cost involved.
The above three principles are employed in
a case of previous C.S. on booking of a case. The pregnancy is
monitored and the events on subsequent visits noted attentively.
Gain in weight that has more an adventitious prognostic
significance is kept a watch on. Fetal growth noted and the rise
or fall in hemoglobin attended to. As the pregnancy advances and
if the previous abdominal scar was vertical subumbilical than an
inscisional hernia can become obvious. Nothing much really
requires to be done for this, at this stage. But, if the skin
over the hernia gets ulcerated due to stretching, then admission
of the case for dressing is warranted. Also bed rest in such
cases will arrest the pressure on the skin
When the pregnancy
zeroes down on term two vital decisions are to be taken:
Vaginal delivery OR
Cesarean section.
Points in favor of vaginal delivery are:
Previous lower segment C.S.
Previous non recurrent indication
Presently no malpresentation
Adequate pelvis
Presently no placenta previa
No
cephalic pelvic disproportion
If these points are fulfilled one can plan a vaginal delivery,
if not a repeat cesarean section.
Risks Of Vaginal Trial of Labour:
Risks of a trial are inherent and
understandable. Among the 17,613 trial-of ???labor cases logged
(attempt rate 60.64%), the success rate was 73.73% (65.56% after
inducing labor and 75.06% after the previous-cesarean group:
maternal febrile episodes (relative risk (RR) 2.77, thromboembolic
events (RR 2.81), bleeding due to placental previa during
pregnancy.(RR 2.06), uterine rupture ( 92cases: RR 42.18), and
perinatal mortality ( 118 cases, including six associated with
uterine rupture: RR 1.33). The post cesarean group also showed a
0.28% rate of peripartum hysterectomy (81 cases: RR 6.07). There was
one maternal death in the group, compared with 14 maternal deaths in
the group without previous cesarean (no statistical significance).
The risk of uterine rupture for patients with previous cesareans was
elevated in the trial-of-labor group compared with the group without
trail of labor (RR 2.07), but all other maternal risks, including
peripartum hysterectomy were lower. When comparing the women having
a trial of labor, the 70 with uterine rupture more often had induced
labor (24.29% compared with 13.92% in the nonrupture group, had
epidural anesthesia (24.29% compared with 8.44%:), had an abnormal
fetal heart rate tracing (32.86% compared with 8.53%:), and had
failure to progress (21.43% compared with 7.98%). Thus, a history of
cesarean delivery significantly elevates the risks for mother and
child in future deliveries. Nonetheless, a trial of labor after
previous cesarean is safe. Induction of labor, epidural anesthesia,
failure to progress, and abnormal fetal heart rate pattern are all
associated with failure of a trial of labor and uterine rupture. (Rageth
JC-1999)
A quality psychological support is also
necessary. Results underline that patients are more disposed to
accept the operation in repeat cesarean rather than in primary
cesarean. Women who have a repeat cesarean section are more likely
to accept this kind of delivery since the beginning, with positive
effects on their post operative course. Women who have a
repeat cesarean section face more serenely not only prenatal but
also post-natal period and show less serious psychophysical sequel
with respect to primary cesarean section because of their previous
experience. As a result, an appropriate psychological support
coupled with adequate information can reduce discomfort in cesarean
patients. (Bique C 1999)
It is needless to over assert the need for
biophysical fetal monitoring both on USG and cardio tocography. As
term approaches in such cases, CTG is regularly repeated and any
unfavorable feature, warrants immediate and appropriate
intervention.
If the pregnancy has reached term and a trial
for vaginal delivery has been carefully decided, it is advisable to
induce labour. Now a days it is not considered as harmful and PGE2
gel can be safely used for this purpose. Some workers have expressed
fears in the past about giving trials in unknown scars. This
was recently reviewed. Pruett et all reviewed 393 patients
undergoing trial of labor after one or more previous section. In
this study, 300 patients had an unknown type of uterine scar: the
rate of vaginal delivery and maternal and fetal morbidity was no
different in those patients with an unknown prior uterine incision
compared with those having a known prior low transverse incision.
Similar findings have been noted in our unit.
At term the labor is induced and closely
monitored. Any signs of feto maternal distress in the form of
tachycardia or maternal uterine scar tenderness is dangerous and C.S.
be resorted to. Fetal Distress In Labor: Although this is an
acceptable indication for cesarean section, identification of the
fetus at risk from hypoxia in not always easy. The diagnosis of
hypoxia based on cardio-tocography alone has led to an increase in
CSR. Some workers found that fetal distress was the cause of
one quarter of cesarean sections in their study. Ayromlooi &
Garfinkel (1980) found that fetal blood sampling has helped reduce
CSR. Mac Donald et al, however, have shown that electronic fetal
monitoring did not influence the number of cesarean sections in
low-risk pregnancies at the National Maternity Hospital, Dublin.
Development of an unexplained tachycardia &/or
vaginal bleeding in a mother with previous C.S. scar can indicate an
early dehiscence and immediate intervention is the rule. The role of
Intrapartum CTG monitoring in such cases was recently reviewed.
Silent tracing appearing during cesarean section usually does not
indicate fetal distress. Poor intra-cesarean fetal heart tracings
were associated with worse indicators of neonatal well being.
Although umbilical pH was lower than scalp values, when the
correction described in the literature was applied, the difference
was of little clinical relevance. It is concluded that anesthetic,
pharmacological and surgical events have slight repercussion in
fetal well being. However, in a few cases fetal heart monitoring
during cesarean section could detect otherwise undiagnosed cases of
transient ischaemia or depression in the fetus.(De Meeus, JB-1998)
If the labor progress is satisfactorily
reinforced by a partogram, even augmentation with a syntocinon drip
can be done. However care should be taken to prevent an unmonitored
administration. Head above the brim is more dangerous than below.
This is because the head above can rummage into the previous scar
and it is advisable to wait for starting syntocinon upto that time
as and when the major portion of the head descends below, the inlet.
Once the trial
progresses satisfactorily, it is advisable to cut short the second
stage with ventouse or forceps as per the pre-requisites fulfilled.
Labor does not end till the complete delivery
of placenta is ensured. Part of the placental tissue can be adherent
to the scar and warrant a manual removal. Routine and universal
exploring of the uterus especially the scar line after delivery is
now not advocated. Individualization of the case is the order of the
day.
MANAGEMENT OF TRIAL OF SCAR (TOS) IN S.S.G HOSPITAL, BARODA: -
The perinatal mortality rate for patients with
previous section is higher than the rest of the population, and the
need for antenatal surveillance is emphasized. We believe that trial
of labor is as safe for the fetus as elective repeat section. In our
unit the following rules are applied in the management of TOS.
Oxytocin is administered when required, to a
maximum of 12 m U/min, but may be increased to 40 mU/min upon a
consultant decision. Induction of labor is associated with high
success rates and does not increase the true uterine rupture,
provided proper patient selection is made and induction performed
and supervised correctly. We believe the use of artificial rupture
of the membranes and intravenous oxytocin is safe, when properly
managed. Automatic monitoring of maternal blood pressure and pulse
recordings should be made at 15-min intervals.
Epidural analgesia for TOS: we demonstrated
that epidural analgesia for patients undergoing TOS is safe for
mother and fetus in properly conducted trial of labor. Patients are
often having their first vaginal delivery and require more pain
relief. An increased instrumental delivery rate can be anticipated
in patients with trial of labor and a further 15-20% may require
termination of trial by cesarean section. Both procedures are often
easier and safer under regional analgesia.
Anaesthetic and pediatric staff is informed of
the trial.
Compatible cross-matched blood should always be
available.
A resident doctor is in attendance at all
times.
Cesarean section theatre is available.
Trial of labour following previous section is
associated with little risk of true rupture, and with no added risk
to the fetus. Our policy and management have helped maintain over
the past 5 years an overall CSR of 10-11%. Over the same period, the
vaginal delivery rate was 82% no perinatal death was associated with
delivery and there was total elimination of true rupture.
In case the mother does not satisfy the
criteria for a successful trial, than cesarean section is warranted.
A bad disfigured previous scar has to be excised. It is a practice
to follow the previous scar and not to create a new scar on the
abdomen. Omental adhesions to the previous scar are frequently found
and be lysed quickly. The bladder can be densely adherent
warranty a sharp dissection. It is not always possible to go through
the previous scar of the uterus as the decision regarding the
uterine scar placement is taken in relation to the fetal biparietal
diameter. Current practices of not suturing the visceral peritoneum
and using synthetic absorbable suture material will reduce the
operative difficulties in a case for repeat cesarean section.
EPILOGUE: -
It is sad but true that defensive obstetrics
is practiced more often today. The National Institutes of Health (NIH)
consensus committee on cesarean section recommends that hospitals
with appropriate facilities, service and staff for prompt emergency
cesarean birth in proper selection cases should permit a safe trial
of labour and vaginal delivery for women who have had a previous
lower segment cesarean section. It also supports the belief that the
physician who opts to allow appropriately selected patients to
undergo a trial of labour, while following the well-established
guidelines for management of such patients, would be subjected to a
very low risk of a successful suit for malpractice. Because the
medical profession is vulnerable, it must be prepared to fight back
against the litigious urge and the small groups of unprincipled
lawyers who bring discredit to the legal profession, unnecessary
anxiety to the doctor, and inflict hardship, not to mention possible
dangers, on the unfortunate and unsuspecting patient. What better
way to do this than follow through with what we believe to be the
correct management in a given circumstance and so obviate this
growing cancer within our specialty known as defensive obstetrics.
In management of patients with prior cesarean section, it must be
realized that intensive antenatal surveillance is required. In our
unit we demonstrated that perinatal mortality associated with
delivery following previous cesarean section is increased
irrespective of the method of delivery. The risk of true uterine
rupture is extremely low with modern obstetric practice. In S.S.G.
Hospital, Baroda the incidence of true rupture in the last 5 years
was 0.2% and hence it must not be retained as the excuse for
choosing elective repeat caesarian delivery. At any instance of
time, previous cesarean case is a high-risk pregnancy. An
alert and wise obstetric decision with strong individualization is
the rule of the day.
REFRENCES:
Ayromlooi J, Garfinkel R: Int. Jr. Obst. Gynecol.:1980, 17,391
Bique
C: Acta Obstet Gynecol Scand 1999, Mar;78(3):198-201
De Meeus JB: Eur J Obstet Gynecol Reprod.
Biol 1998 Oct:81(1):65-8,
Gilbert
L, Saunders N, Sharp F: Brit. Jr. Obst. & Gynecol: 1988, 95,1312.
Mac
Donald D, Grant A, Pereira M: Am J Obstet Gynecol.,1985,154,524
Meier & Porreco Am J Obstet Gynecol, 1982,144,671
Paul,
Phelan, Yen: Am J Obstet Gynecol,1985,151,297
Pruett
K M, Kirshon B, Cotton D B: Am J Obstet Gynecol,1988,159,807
Rageth
JC: Obstet Gynecol, 1999,Mar, 93(3): 332-7
Unger
JB: Am J Obstet Gynecol 1998 Dec; 176(6Pt1):1473-8- |
