ORIGINAL
/ RESEARCH
Induction
of Labour by Foley's Catheter
Binti
R Bhatiyani, Parul S Shah, Jignesh J Kansaria, Shashank V Parulekar
Foley’s Catheter was
used for pre-induction cervical priming and to enhance induction of labour in
52 patients (out of which 38 were primis and 14 were multis). The procedure
was found to be a safe and effective method for induction of labour in patients
with unripe cervices with mean induction of labour to delivery time of 8 hours.
INTRODUCTION
The unripe cervix may present a problem when
delivery is indicated prior to the spontaneous
onset of labour. Conditions such as preeclampsia, IUGR or postdatism pose a
problem for delivery when the cervix is not favourable common manipulative procedures
to ripen the un-favourable cervix include the application of prostaglandin gel,
intracervical tents and Foley’s catheter. The purpose of this study was
to improve cervical compliance, ripen the cervix prior to induction of labour
and to improve the Bishop score rather than to induce labour itself.
MATERIAL AND METHODS
Fifty two patients with medical and obstetric indications for induction of labour
and with unfavourable cervices (modified Bishop’s score 0-4) were recruited.
The study group comprised 38 primigravidae (73%) and 14 multigravida (27%).
The mean maternal age was 30 (Table 1). There were 12 patients with post dates
(23%), 6 had IUFD (11.5%), 10 had IUGR (19.2%), 14 had preeclampsia (27%), 8
had oligohydramnios (15.3%) and two patients (3.8%) had anencephalic foetuses
(Table 2). On admission the foetal presentation was noted and cervical assessment
was done. The anterior lip of cervix was grasped with sponge holding forceps
under aseptic conditions and the balloon was distended with 30 ml normal saline.
The catheter was then pulled outward with slight tension and tapped to the anterior
abdominal wall.
During selection of patients for this procedure, contra indications for labour
were contraindications for balloon use in general, placental localization by
USG was a prerequisite before performing the procedure patients with ruptured
membranes were excluded from the study. Cervical scoring was done after 6 hours
after removing the Foley’s, in cases it was not spontaneously expelled.
When the catheter was expelled spontaneously, the cervix was found to be dilated
to at least 3 cm with significant effacement. In 32 patients the catheter was
spontaneously expelled. Labour was then initiated with oxytocin infusion and
artifical rupture of membranes.
RESULTS
Forty out of 52 patients delivered vaginally, 4 patients failed to progress
and the procedure was terminated in 2 patients who developed foetal distress.
Five patients had thin meconium stained amniotic fluid with borderline pelvis
and were then up for caesarean section. One patient had cord prolapse and was
then up for Caesarean section. In one patient the catheter was reinserted for
another 6 hours when the cervix failed to dilate. There were no cases of infection,
ruptured membranes, haemorrhage or other complication attributed to balloon
catheter use.
Mean induction to delivery interval was 8 hours.
DISCUSSION
The results from this study show that an inflated Foley’s catheter was
effective in ripening the unfavourable cervix prior to induction of labour.
Embery and Mollison1 advanced a theory on the possible mechanism by which a
Foley’s catheter effects changes on the various relevant components of
the Bishop score (dilatation, effacement and consistency). The mechanical action
of the Foley’s strips the foetal membranes from the lower uterine segment
and causes rupture of lysosomes in the decidual cells, part of which is phospholipase
A. These lytic enzymes act on phospholipids to form arachidonic acid which in
turn is converted to prostaglandin A which improves the consistency and effacement
of the cervix.
After the catheter balloon is inflated a variable time period is allowed in
many studies for spontaneous expulsion and adequate ripening. Whereas in some
studies2-7 the balloon is removed after 8 to 15 hours, others wait until it
get expelled spontaneously.1,8-11 In our study we had primed the cervix for
6 hours before removing the catheter. If the cervical score criteria had not
been met, a few studies have reinserted the balloon catheter.12,13 In our study,
we had reinserted the catheter for another 6 hours in one patient who had a
poor bishop score. In some patients, oxytocin drip was started after removing
the catheter and ARM was done when the cervix opened up to 2 cm or more.
Whereas some series suggest that spontaneous labour follows balloon expulsion
in only few patients, others2,8,12,10.7 suggest that this may occur in 30-60%
of the patients. This is consistent with the concept that labour is correlated
with myometrial preparedness and contractility in as much as both the cervix
and myometrium are under mutual endocrine-paracrine regulation. Thus it is reasonable
that the unripe cervix is associated with lower concentrations of myometrial
oxytocin receptors and gap junctions. This is also suggested by the relatively
high rates of operative vaginal deliveries and Caesarean deliveries for dysfunctional
labour. In our series, 1/3rd of caesarean deliveries were carried out for dysfunctional
labour. The rates of caesarean deliveries vary significantly among series and
range from 4 to 46%. These rates however reflect the high risk nature of the
population undergoing cervical ripening.
Side effects of balloon cervical ripening
Most series report very few side effects of cervical ripening by a Foley’s
catheter, the most common are intrapartum or postpartum fever and vaginal bleeding
after insertion.1,2,5,6,8 Less frequent side effects reported are rupture of
membranes,
displacement of the presenting part or umbilical cord prolapse.13
Clinical experience and review
TABLE
7
Comparison of induction to delivery interval |
 |
| Study
done by |
Year |
Induction
to delivery
interval (hours) |
1.
St Onge and Connors10 |
1995 |
16 + 1.7 |
| 2.
Schreyer et al2 |
1989
|
6.4 |
| 3.
James et al6 |
1994 |
7.3 |
| 4.
Sherman et al16 |
1996 |
12.8 |
| 5.
Present series |
2002 |
8 |
| |
|
|
CONCLUSION
| |
TABLE
8 |
|
|
| Study
done by |
Year |
Operative
vaginal delivery % |
| 1.
Lyndrup et al12 |
1994 |
19 |
| 2.
James et al6 |
1994
|
26 |
| 3.
St Onge and Connors10 |
1995 |
38 |
| 4.
Sherman et al16 |
1996 |
8 |
| 5.
Present series |
2002 |
9 |
| |
|
|
TABLE
9
Comparison of operative vaginal delivery (percentage) |
|
| Study
done by |
Year |
Percentage(%) |
| 1.
Rouben and Arias5 |
1993
|
34 |
| 2.
Lyndrup et al5 |
1994
|
19 |
| 4.
St Onge and Connors10 |
1995
|
38 |
| 5.
Present series |
2002
|
23.07
|
| |
|
|
TABLE
10
Comparison of change in cervical scores |
|
| Study
done by |
Year |
Change
in
cervical score |
| 1.
Lyndrup et al12 |
1994
|
2.2
|
| 2.
James et al6 |
1994
|
3.5
|
| 3.
St Onge and Connors10 |
1995
|
2.9 |
| 4.
Sherman et al16 |
1996 |
4 |
| 5.
Present series |
2002
|
4 |
| |
|
|
Cervical ripening with extraamniotic catheter possesses the advantage of simplicity,
low cost, reversibility and lack of systemic or serious side effects.
However ripening with Foley’s subsequently requires oxytocin stimulation
augmentation.
While the effect of Foley’s catheter might not be as pronounced as extra
amniotic prostaglandin, it is sufficient to allow a successful induction of
labour and reduces the induction delivery interval from what it would have
been with an unripe cervix. Cases of uterine hypertonous and foetal bradycardia
have been reported following the use of prostaglandin (Mackenzie and Embery
1978; Mackenzie and Embrey 1979) and this necessitates cardiotocographic monitoring
when these potent agents are used. This does not apply to the use of Foley’s
catheter which is cheap and easily available.
REFERENCES
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