TABLE 1: CLINICAL CHARACTERISTICS OF RESPONDENTS
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Variable Parity
nulliparous multiparous χ2 P n (%) n (%)
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110(72.4) 42(38.2) - - Age group (years)
< 25 10 (9.1) 0 (0.0) 4.29 0.1170
25 – 34 84 (76.3) 34 (81.0)
35 and above 16 (14.5) 08 (18.0) Mean age 30.4 ± 4.3
Cervical ripening time
< 12 hours 24 (21.8) 26 (38.1) 4.15 0.0416
>12 hours 86 (78.2) 16 (6I.9) Duration of labour
< 12 hours 98 (89.1) 38 (90.5) 0.06 0.5328
>12 hours 12 (10.9) 04 (09.5) Whole process of induction of labour
<24 hours 78 (70.9) 31 (73.8) 0.13 0.7225
>24 hours 32 (29.1) 11 (26.2) Outcome
SVD* 75 (65.5) 37 (95.2) 13.90 0.0000
EMLSCS** 35 (34.5) 05 (04.8) Failed induction rate (%)
31.8 11.9 - -
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* Spontaneous Vertex Delivery X2 - Chi-square
** Emergency Lower Segment Caeserean Section
Failed induction rate amongst the respondent = 26.3%
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Figure 1 - BAR CHART SHOWING THE INDICATION FOR EMERGENCY LOWER SEGMENT CAESEREAN SECTION AMONGST THE WOMEN WITH POST-DATE PREGNANCY
CPD - Cephalopelvic disproportion
0 5 10 15 20 25
CPD Cervical Stasis fetal distress
0 0
5 21
7
7
Nulliparous Multiparous
50 Table 2 - THE MEDIAN VALUES OF PRE-CERVICAL RIPENING CERVICO-VAGINAL FETAL FIBRONECTIN LEVEL, THE CERVICAL RIPENING TIME, THE DURATION OF LABOUR AND THE WHOLE PROCESS OF LABOUR INDUCTION AMONGST THE RESPONDENTS
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Variable N Median U P
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Fetal fibronectin (ng/ml)
Nulliparous 110 45.35 2053.0 0.289 Multiparous 42 46.93
Cervical ripening time (hrs)
Nulliparous 110 15.3 1910.0 0.099 Multiparous 42 14.3
Duration of labour (hrs)
Nulliparous 110 7.10 2155.0 0.523 Multiparous 42 6.45
Whole process of labour induction (hrs)
Nulliparous 110 22.05 1929.0 0.116 Multiparous 42 20.02
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Note: U= Mann Whitney U test
51
Figure 2 - HISTOGRAM SHOWING THE DISTRIBUTION OF CERVICO-VAGINAL FETAL FIBRONECTIN AMONGST THE WOMEN WITH POST DATED PREGNANCY
52
Table 3: ASSOCIATION BETWEEN PRE-CERVICAL RIPENING CERVICO-VAGINAL FETAL FIBRONECTIN LEVEL AND CERVICAL RIPENING TIME IN WOMEN WITH POST-DATED PREGNANCY UNGERGOING CERVICAL RIPENING AND INDUCTION OF LABOUR
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Variable Fibronectin Level Total χ2 P
Low High _______________________________________________________________________
Nulliparous n (%) n (%) n (%)
Cervical ripening <45.35ng/ml >45.35ng/ml
< 12 hours 20 (83.3) 4 (16.7) 24 (100) 15.09 0.000
>12 hours 34 (39.5) 52 (60.5) 86 (100)
Total 54 (49.1) 56 (50.9) 110 (100)
Multiparous
Cervical ripening <46.93ng/ml >46.93ng/ml
<12 hours 10 (62.5) 6 (37.5) 16 (100) 1.62 0.2037
>12 hours 11 (42.3) 15 (57.7) 26 (100)
Total 21 (50.0) 21 (50.0) 42(100)
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53
Figure 3: SCATTERED DIAGRAM SHOWING THE CORRELATION BETWEEN CERVICO-VAGINAL FETAL FIBRONECTIN LEVEL AND CERVICAL RIPENING TIME AMONGST NULLIPAROUS WOMEN WITH POST DATED PREGNANCY
54
Figure 4: SCATTERED DIAGRAM SHOWING THE CORRELATION BETWEEN CERVICO-VAGINAL FETAL FIBRONECTIN LEVEL AND CERVICAL RIPENING TIME AMONGST MULTIPAROUS WOMEN WITH POST DATED PREGNANCY
55
Table 4: ASSOCIATION BETWEEN PRE-CERVICAL RIPENING CERVICO-VAGINAL FETAL FIBRONECTIN LEVEL AND DURATION OF LABOUR IN WOMEN WITH POST-DATED PREGNANCY UNGERGOING CERVICAL RIPENING AND INDUCTION OF LABOUR
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Variable Fibronectin Level Total χ2 P
Low High ___________________________________________________________________________
Nulliparous n (%) n (%) n (%)
Duration of labour (<45.35ng/ml) (>45.35ng/ml)
< 12 hours 48 (49.0) 50 (51.0) 98 (100) 0.22 0.6377
>12 hours 6 (50.0) 6 (50.0) 12 (100)
Total 54 (49.1) 56 (50.9) 110 (100)
Multiparous
Duration of labour (<46.93ng/ml) (>46.93ng/ml)
<12 hours 19 (50.0) 19 (50.0) 38 (100) 0.00 1.000
>12 hours 2 (50.0) 2 (50.0) 4 (100) Total 21 (50.0) 21 (50.0) 42 (100)
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56
Figure 5: SCATTERED DIAGRAM SHOWING THE CORRELATION BETWEEN PRE-CERVICAL CERVICO-VAGINAL FETAL FIBRONECTIN LEVEL AND DURATION OF LABOUR AMONGST NULLIPAROUS WOMEN WITH POST DATED PREGNANCY
57
Figure 6: SCATTERED DIAGRAM SHOWING THE CORRELATION BETWEEN PRE-CERVICAL CERVICO-VAGINAL FETAL FIBRONECTIN LEVEL AND DURATION OF LABOUR AMONGST MULTIPAROUS WOMEN WITH POST DATED PREGNANCY
58
Table 4: ASSOCIATION BETWEEN PRE-CERVICAL RIPENING CERVICO-VAGINAL FETAL FIBRONECTIN LEVEL AND THE WHOLE PROCESS OF INDUCTION OF LABOUR IN WOMEN WITH POST-DATED PREGNANCY UNGERGOING CERVICAL RIPENING AND INDUCTION OF LABOUR
___________________________________________________________________________
Variable Fibronectin Level Total χ2 P
Low High ___________________________________________________________________________
The whole process of induction of labour
Nulliparous n (%) n (%) n (%)
<45.35ng/ml >45.35ng/ml
< 24 hours 36 (46.2) 42 (53.8) 78 (100.0) 0.93 0.33360
>24 hours 18 (56.3) 14 (43.8) 32 (100.0)
Total 54 (49.1) 56 (50.9) 110 (100.0)
Multiparous < 46.93ng/ml >46.93ng/ml
<24 hours 15 (48.4) 16 (51.6) 41 (100.0) 0.12 0.7256
>24 hours 6 (54.5) 5 (45.5) 11 (100.0) Total 21 (50.0) 21 (50.0) 42 (100.0)
___________________________________________________________________________
59 Figure 7: SCATTERED DIAGRAM SHOWING THE CORRELATION BETWEEN PRE-CERVICAL RIPENING CERVICO-VAGINAL FETAL FIBRONECTIN LEVELS AND THE WHOLE PROCESS OF INDUCTION OF LABOUR AMONGST NULLIPAROUS WOMEN WITH POST-DATED PREGNANCY
60
Figure 8: SCATTERED DIAGRAM SHOWING THE CORRELATION BETWEEN PRE-CERVICAL RIPENING CERVICO-VAGINAL FETAL FIBRONECTIN LEVELS AND THE WHOLE PROCESS OF INDUCTION OF LABOUR AMONGST MULTIPAROUS WOMEN WITH POST-DATED PREGNANCY
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CHAPTER 5
DISCUSSION
In minimising the risk of potentially unsatisfactory outcome that occurs with prolonged pregnancy, induction of labour is usually performed. The success of this common obstetric procedure relies on initiating the process in women with favourable cervices. Recent research works are focussing on the objective cervical assessment for favourability of the cervix for induction of labour and determination of its success. Hence, cervico-vaginal fetal fibronectin, a biochemical marker, as a predictor of cervical ripening time and duration of labour is the focus of this study.
This study was carried out among pregnant women with post-dated pregnancy which happens to be a very common indication for induction of labour31, 53.The ages of these women range between 21 - 43 years with a mean age of 30.4 ± 4.3 years. This is within the expected reproductive age group with no statistical significant.
In this study, the population consists of both nulliparous and multiparous women. Others have carried out similar study just within nulliparous women, others consider both like this study and some other did not make contra-distinction in the grouping 16, 26, 54, 55, 56, 57. Nulliparity is an important risk factor
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for prolonged labour and induction of labour among them is most challenging due to the cervical factor29, 53, 54 . In this study, it took longer than 12 hours to achieve cervical ripening in 78% of study population. Cervical ripeness exerts a significant influence upon induced labour outcome 15, 53. Furthermore, nulliparity is a risk factor for prolonged pregnancy which is borne out in this study, as 72% of the study group were nulliparous with postdated pregnancy compared to 28% of the multiparous women6, 56, 57.
Seventy three percent of the women in this study had successful vaginal delivery with a failed induction rate of 26% and a resort to Caesarean section following indications for fetal distress, cephalopelvic disproportion and cervical stasis. This is comparable to a similar study in South - South Nigeria by the findings of Osaheni et al who reviewed the outcome of labour induction53. The study had a failed induction rate of 24.1% and an overall success rate of 75.9%
was reported with similar indications for Caesarean section. These findings are similar to the 70.3% reported in the United States60. However, 91% success rate was recorded by Ekele et al when only foley catheter was used as a cervical ripening method in women with varying indications and gestational ages for induction of labour59. In this case, the foley catheters were left in-situ for as long as it was expelled spontaneously whereas in this study, gentle traction was applied in some of the cases.
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A greater number of the women delivered within 24 hours and the induction-delivery intervals were of median values of 22.05 hours and 20.02 hours in the nulliparous and multiparous women respectively in this study. This is similar to a study in which subjects who used single balloon catheter as method for cervical ripening among nulliparous women had an induction delivery interval spent of 23.2 hours within a range of 20.8 - 25.8 hours60. Also, Jindal et al had similar induction-delivery time interval of 19.45 hours amongst the women who had foley catheter as cervical ripening method61.
The role of fetal fibronectin in the success of labour induction had only hitherto been largely investigated mostly in Caucasians and study carried out in south west Nigeria commonly found that fetal fibronectin is expected to be present in cervicovaginal sample at term gestation16, 54, 55, 56, 57 . A quantitative assessment in this study observed a range of 32 - 402.40 ng/ml with median value of 45.35ng/ml and 46.93ng/ml in the cervico-vaginal samples for the nulliparous and multiparous women respectively.
Lockwood et al found quantitative values < 60ng/ml in women at 39 weeks as a prediction of pregnancy that would go beyond 41 weeks; while Blanch et al and Ahner et al, with qualitative assessment, suggested a predictor of the success of labour induction54, 55, 63. In this study, values above the median values were suggested as positive or high fetal fibronectin levels in the
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cervicovaginal samples; while negative or low levels are values below the values with respect to parity.
Conflicting reports have however been observed using cervico-vaginal fetal fibronectin as an objective marker as a predictor of success of labour induction. Ahner et al were the first to establish a correlation of fetal fibronectin results with successful labour induction55. They noted that fibronectin - positive patients had shorter intervals to delivery than fibronectin-negative patients in a qualititative assessment of fetal fibronectin in cervicovaginal sample and in women at term but with varying gestational ages and indications for induction of labour. In as much as the Blanch et al study did agree with the Ahner et al findings but their opinion was different when they analysed the multiparas differently54, 55. They found out that cervical dilatation as component of modified Bishop score had a better predictive value rather than relying on the fetal fibronectin level in the multiparous women. However, these studies misoprostol was used as cervical ripening method. Adeniji et al shared the same opinion with the above mentioned work but stopped short of investigating the relationship between the qualitative assessment of fetal fibronectin in cervico vaginal sample and the cervical ripening time using two methods of cervical ripening methods - transcervical foley catheter and Misoprostol16. The qualitative study concluded
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that positive fetal fibronectin predicted shorter cervical ripening time16. However, this result was common for the patients in the misoprostol group regardless of their parity and gestational ages at term.
This was a quantitative study which was carried out among women with post-dated pregnancy with specific gestational age using only transcervical foley catheter as cervical ripening method and the relationship of quantitative levels of fetal fibronectin to cervical ripening time, duration of labour and whole labour induction process (induction- delivery interval). Significant low levels of fetal fibronectin in nulliparous women suggested cervical ripening time less than 12 hours and otherwise when levels are higher. Eventually, an insignificant correlation was observed between the cervicovaginal fetal fibronectin levels and cervical ripening time with the nulliparous women.
Findings were similar among the multiparous patient but the fetal fibronectin levels were not statistically significant in this case and an insignificant correlation was observed as well. With respect to the duration of labour, there was no significant relationship and no correlation with cervicovaginal fetal fibronectin levels. For the whole process of labour induction (induction-delivery interval), there were no significant relationship as well and an insignificant correlation was observed in both nulliparous and the multiparous women.
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The findings of this study are similar to the work carried out by Dale Ojitiku et al56. Quantitative fetal fibronectin levels in cervico vaginal fetal fibronectin samples were assessed in the women at gestational age of 40 weeks + 11 days and a relationship between the values and the latent phase of labour (cervical ripening time), the length of labour and the induction-delivery time were observed. However, it was carried out only among nulliparous women. A single ripening method was used - Prostin. No relationship was found between the fetal fibronectin and the variables - latent phase, length of labour and induction-delivery interval56. They concluded that the modified Bishop score was reliable and better as a predictive tool. Some other study that used transcervical catheter as the ripening method, though noticed a shorter induction delivery interval with positive fetal fibronectin women, there were no appreciable difference between the negative fetal fibronectin women as regards to these timing and the eventual outcome of the labour process27. It disregarded the fetal fibronectin further since it could not help arrive at which of the groups would end up with caesarean section or vaginal delivery which is the basis for determining a successful induction of labour. Also, Reis et al in their study also found out that only obstetric history and digital examination predicted accurately vaginal delivery within 24 hours and were independently associated with labor duration; while fetal fibronectin assessment and
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ultrasound scan measurement of the cervical length failed to predict accurately the outcome of induced labour at term42.
Fetal fibronectin presence in cervico-vaginal samples may actually not relate to the labour process as cervical ripeness does not solely influence the process and its outcome. Lockwood et al, actually suggested it could predict a pregnancy that could be postdate and values ≥ 60ng/ml at thirty-ninth week gestation suggested spontaneous labour within 7 days63. On the other hand, there were other studies that had a counter opinion, in which they found out that high level of Fetal Fibronectin at term did not predict impending labour64.
Investigators have tried to express cervical ripeness using different definitions and in most cases the complex nature of labour has not been addressed.
Maybe the normal disruption of the choriodecidual membrane is incomplete in
‘‘postdated’’pregnancy and results in variable expression of fetal fibronectin, which thus, does not bear any relationship to impending labour. Although, fetal fibronectin is associated with cervical dilatation the exact relationship is not known. The mechanisms involved in pre-term labour may be different from those in post-term pregnancies. The expression of fetal fibronectin in the cervico-vaginal fluid maybe part of a much larger series of events yet to be described and it is possible that ‘‘occult’’ leakage of amniotic fluid may also affect the results of these studies.
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The limitations encountered in the study were firstly, the difficulties with accurate determination of the cervical ripening time, the duration of labour and the whole labour process (the induction-delivery-interval). The cervical ripening time could only be calculated from the insertion of transcervical catheter and when spontaneous expulsion occurred or the time when the removal was by gentle traction. Hence, the exact time of cervical ripening couldn’t be determined. Furthermore, determining the exact time when the induction process ended in cases of failed induction was also a limitation.
Secondly was the subjectivity of the digital assessment of the cervix using the modified Bishop scoring system to determine the favourability of the cervix and the progress in labour. Finally, the various factors in labour that can only be accounted for during labour, that is, the fetal adaptability to the stress of labour, the moulding capability of the presenting part, fetal attitude, the pelvic give and maternal fortitude to labour.
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CHAPTER 6
CONCLUSION AND RECOMMEDATION