Management of Foley Catheter Induction Among Nulliparous Women

A Retrospective Study

Heidi Kruit; Oskari Heikinheimo; Veli-Matti Ulander; Ansa Aitokallio-Tallberg; Irmeli Nupponen; Jorma Paavonen; Leena Rahkonen

Disclosures

BMC Pregnancy Childbirth. 2015;15(276)

Discussion

We found that the need for oxytocin for induction and early epidural analgesia were associated with caesarean delivery in nulliparous women undergoing IOL by Foley catheter. Gestational diabetes was associated with maternal intrapartum infection, while early epidural analgesia was associated with neonatal infection. Surprisingly, Bishop score at the start of IOL, duration of the balloon remaining in the cervical canal, timing of amniotomy or timing of oxytocin induction had no association with caesarean section or infections. We acknowledge the limitations of our retrospective single-institution study; we may have been susceptible to selection bias, and our results may not be applicable to other settings.

The caesarean section rate in our study was 39.1 %. Frederiks et al. found a similar 42 % caesarean delivery rate in nulliparous women with a variety of induction methods.^[8] In another recent study, the overall rate of successful IOL in combination with different methods and an unfavourable Bishop score (<6) at 41 weeks of gestation was 51.3 %.^[7] We found a higher rate of successful labour induction resulting in vaginal delivery than these other recent studies. (The caesarean section rate among the 59 excluded women with sequential use of Foley catheter and intravaginal prostaglandin was even higher, 45.8 % (n = 27)).

The degree of cervical ripeness in this study was assessed using the Bishop score, which was originally derived from observations made on multiparous women.^[12] We used Bishop score ≥ 6 as a marker for a ripened cervix, at which time amniotomy and oxytocin augmentation may be used. Perhaps a more modern concept for a favourable cervix in a nulliparous women would be Bishop score ≥ 8.^[13]

In previous studies, low Bishop score (<5), increased maternal age, obesity and large birth weight have been associated with induction failure and operative delivery.^{[4,5,8,14–17]} This trend was also seen in our study. However, in multivariate regression analysis, only the need for oxytocin to induce contractions and early epidural analgesia remained associated with caesarean delivery, as also seen in a previous study.^[18] It has been suggested that since IOL, oxytocin use, low parity, prelabour rupture of membranes and obesity are all linked with increased caesarean delivery risk,^[19] this may explain the increased caesarean rate related to early epidural.^[20] However, the request for analgesia early in labour (cervical dilation of ≤ 3 cm) may be a marker for other risk factors for caesarean delivery.^[21]

The most common indication for caesarean delivery was failure to progress (failed induction and labour arrest), as was also noted in previous studies.^[3,5] Several studies suggest that a substantial proportion of women undergoing IOL and remaining in the latent phase for 12–18 hours with oxytocin administration and ruptured membranes will deliver vaginally if induction is continued.^[22–24] Previous studies have shown that active labour does not occur until about 6 cm of cervical dilation in women undergoing IOL, and that a diagnosis of failed induction should be made with caution prior to that stage.^[25,26] ACOG clinical guidelines recommend that arrest in the first stage of labour should be reserved for women ≥ 6 cm of cervical dilation with ruptured membranes who are failing to progress despite of 4 hours of adequate uterine activity or 6 hours of oxytocin administration without cervical change.^[11] In our study, the definitions for failed induction and arrest of labour varied. This suggests that some women undergoing IOL in our clinic might have been diagnosed with failed induction or labour arrest too early.

Macones et al. demonstrated that early amniotomy at ≤ 4 cm of cervical dilation during IOL shortened the time to delivery in nulliparous women, but did not impact the caesarean delivery rate,^[27] which was in line with our results. Oxytocin is more often used with Foley catheter IOL compared to pharmaceutical IOL or spontaneous labour.^[3] Oxytocin use was high in our study, which may partly explain our high caesarean section rate. The timing of oxytocin administration for IOL was not associated with caesarean section or maternal or neonatal infections. To our knowledge, no other study has focused on this in the context of Foley catheter IOL.

In one previous study, Foley catheter IOL was associated with increased infectious morbidity.^[28] In several other studies, as well as in a recent Cochrane review, Foley catheter IOL has not been linked to increased maternal or neonatal infection rates.^[3,29,30] This is in agreement with our results. In our study, gestational diabetes was associated with maternal intrapartum infection. In a previous Danish study, type II or gestational diabetes showed a modestly increased risk of post-caesarean infection.^[31] In our study, the rate of neonatal clinical sepsis was similar to that in previous studies,^[3,29] but the rate of suspected neonatal infections was higher. We believe that potential bias related to Foley catheter induction and longer induction-to-delivery interval resulted in more neonates being admitted to the neonatal ward for observation or antibiotic administration. The duration of labour after ruptured membranes has previously been linked to neonatal infections.^[9,10] In our study, early epidural analgesia was associated with caesarean delivery and neonatal infections. This can be explained by the prolongation of labour.

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Table 1. Main indication for IOL ( n = 432)
	n	Percent
Post-term pregnancy	266	61.6
Pre-eclampsia/hypertension	56	13
Intrauterine growth restriction	23	5.3
Gestational diabetes	29	6.7
DM I	3	0.6
Oligohydramnion	19	4.4
Obstetric cholestasis	16	3.7
Maternal disease^a	3	0.6
Foetal disease^b	4	1
Psychosocial reasons^c	3	0.6
Decreased foetal movement	6	1.4
LGA	4	0.9

DM I diabetes mellitus type 1, LGA large for gestational age
^aBack pain, heart transplantation, difficulty urinating, ulcerative colitis
^bHeart malformation, Catc-22 h, suspected distress
cMaternal exhaustion, fear of labour, maternal preference

Table 2. Characteristics of the labour induction
	n	Percent
Bishop score ≤ 3 at start of IOL	209	47.9
Time the Foley catheter was retained, median (range)	666	(1–1647)
Spontaneous rupture of the membranes	25	5.8
Spontaneous contractions before balloon expulsion	60	13.9
Oxytocin administration	402	93.1
Oxytocin needed for induction	188	46.7
Early epidural analgesia ^a	15	3.5
Primary inertia ^b	15	3.5

^aOn maternal request in the absence of regular contractions
^bNo contractions despite oxytocin administration for ≥ 6 hours

Table 3. Maternal and neonatal outcomes
	Caesarean delivery n = 169		Vaginal delivery n = 263		p-value
	n	%	n	%	p-value
Maternal outcomes
Prophylactic antibiotic	154	91.1	87	33.1	<0.001
Oxytocin administration	158	93.5	244	92.8	0.78
For induction of labour	103	60.9	85	32.2	<0.001
Epidural/spinal analgesia	129	76.3	241	91.6	<0.001
Received before start of regular contractions	13	7.7	2	0.8	<0.001
Foetal scalp blood sampling	73	43.2	62	23.6	<0.001
Postpartum haemorrhage ≥ 1000 ml	55	32.5	37	14.1	<0.001
Meconium-stained amniotic fluid	59	34.9	61	23.2	0.008
Maternal intrapartum infection	22	13	5	1.9	<0.001
Maternal postpartum infection	12	7.1	5	1.9	0.007
Endometritis	5		4
Wound infection	5		1
Unspecified fever	2		0
Neonatal outcomes
Gestational weeks at delivery, mean (SD)	41.1	(1.3)	41,1	(1.4)	0.83
Male	99	58.6	127	48.3	0.04
Birth weight, mean(SD)	3720	(543)	3530	(483)	<0.001
Macrosomia (>4500 g)	11	6.5	3	1.1	0.004
Apgar 1 min < 7	20	11.8	20	7.6	0.13
Apgar 5 min < 7^a	11	6.5	6	2.3	0.023
Umbilical artery pH ≤ 7.05^b	1	0.6	9	3.6	0.06
Umbilical artery Base excess^b	2	1.3	7	2.8	0.30
Neonatal infection	28	16.6	10	3.8	0.08
Suspected sepsis	15	53.6	6	60	0.001
Clinical sepsis	11	39.3	1	10	<0.001
Unspecified infection	2	1.2	3	30	0.85
Admission to neonatal intensive care unit	4	2.4	5	1.9	0.74
Admission to neonatal ward	43	25.4	24	9.1	<0.001

^aMissing values 4
^bMissing values 23

Table 4. Univariate analysis for caesarean delivery, maternal intrapartum, postpartum and neonatal infections
	n	Caesarean delivery (n=169)^c		Maternal intrapartum infection (n=27)^d		Maternal postpartum infection (n=17)		Neonatal infection (n=38)		Neonatal clinical sepsis (n=12)^e
	n	OR	(CL 95 %)	OR	(CL 95 %)	OR	(CL 95 %)	OR	(CL 95 %)	OR	(CL 95 %)
Maternal age ≥ 37 (years)	43	1.9	1.0–3.6	0.7	0.2–3.1	1.8	0.2–13.9	1.1	0.4–3.2	4.9	1.4–17.0
IVF^a	19	1.4	0.6–3.6	0	0	0.7	0.1–5.8	2	0.6–7.3	0	0
Smoking	61	1	0.6–1.8	1.8	0.7–4.7	1.2	0.3–5.6	1.2	0.5–2.9	2.1	0.5–7.9
BMI ≥ 30 kg/m² (kg/m²)^b	64	1.8	1.1–3.1	1	0.3–3.0	0	0	1.6	0.7–3.7	2	0.5–7.5
Gestational diabetes	81	1.9	1.2–3.1	3.3	1.5–7.4	3.8	0.5–29.2	1.4	0.6–3.1	4.6	1.4–14.6
Pre-eclampsia or hypertension	68	1	0.6–1.8	0.9	0.3–2.8	0		1.5	0.6–3.4	1.5	0.8–9.5
Bishop^a ≤ 3 at the start of induction	206	1.6	1.1–2.4	1.4	0.6–3.0	1.7	0.6–4.7	0.9	0.5–1.8	1.5	0.5–4.8
Cervical effacement > 2 cm at the time of amniotomy	32	0.8–3.4	0.6–2.1	1.1	0.2–4.7	1.5	0.3–7.0	0		0	0
Cervical dilation ≤ 3 cm at the time of amniotomy	19	1.6	0.8–3.4	0.7	0.2–3.0	0.9	0.1–7.7	0.99	0.3–3.0	1.2	0.2–10.0
Time of amniotomy after balloon expulsion
≤2 h vs. >2 h	195	1.4	0.9–2.0	0.9	0.4–2.0	1.6	0.6–4.4	1	0.5–2.1	1.3	0.4–4.3
≤12 h vs.>12 h	47	0.9	0.5–1.7	2.5	0.9–6.5	2	0.3–15.6	0.8	0.3–2.2	1.7	0.4–8.2
Oxytocin for induction of labor	188	3.3	2.2–4.9	1	0.5–2.3	1.1	0.4–3.0	1.2	0.6–2.4	1.6	0.5–5.3
Time of starting oxytocin for IOL after amniotomy
≤3 h vs. > 3 h	103	1.1	0.6–1.9	1.8	0.5–5.8	0.5	0.1–2.5	0.8	0.3–2.4	0.4	0.4–3.9
≤12 h vs. > 12 h	52	1.3	0.7–2.5	2	0.4–9.5			1.8	0.6–5.4	2.7	0.4–19.4
Early epidural analgesia	15	11.2	2.5–50.5	1	0.5–2.3	0.5	0.1–4.1	2.7	0.7–10.0	6	1.2–30.3

IVF; in vitro fertilization, BMI; body mass index
^aMissing values 2
^bMissing values 4
^cMaternal age ≥ 37 (p=0.045), BMI≥30 (p=0.029), gestational diabetes (p=0.01), Bishop ≤ 3 (p=0.018), oxytocin induction (p<0.001), early epidural analgesia (p=0.002)
^dGestational diabetes (p=0.004)
^eMaternal age ≥ 37 (p=0.013), gestational diabetes (p=0.01), early epidural analgesia (p=0.029)

Table 5. Main indication for caesarean delivery ( n = 169)
	n	Percent
Foetal distress	63	37.3
Infection	12	7.1
Failure to progress	85	50.3
Labour arrest	53	31.4
Failed induction	32	18.9
Bleeding	1	0.6
Pre-eclampsia	3	1.8
Umbilical cord prolapse	1	0.6
Maternal exhaustion	2	1.2
Failed vaginal instrumental delivery	2	1.2