INTRODUCTION:

There is a growing trend towards caesarean sections (CS) in developed countries. The most common indication for having an elective CS is a previous CS. Attempting a VBAC, also known as a TOLAC, is a safe and appropriate choice for most women who have had a prior caesarean delivery, including some women who have had two previous CS.

It avoids major abdominal surgery, lowers a woman’s risk of haemorrhage and infection, and shortens postpartum recovery. It may also help women avoid the possible future risks related to having multiple caesareans, such as hysterectomy, bowel and bladder injury, transfusion, infection, and abnormal placental conditions (placenta previa and placenta accreta).

METHODOLOGY:

Researchers of this study have selected all the women who were suitable for TOLAC. References, inclusion, and exclusion criteria were taken from the UK RCOG guidance, and a pro forma was prepared. When patients were admitted, all data and information were collected and completed by the time they were discharged from the hospital.

Cases with a single previous transverse LSCS with or without a history of previous vaginal birth, a singleton pregnancy, and a cephalic presentation were included in our study after informed consent. Women with previous uterine rupture or classical caesarean scars and those who have absolute contraindications to vaginal birth irrespective of the presence or absence of a scar (e.g., major placenta praevia) were excluded from the study.

MAIN OUTCOME MEASURES:

Maternal outcomes evaluated included VBAC success, predictors of success, and maternal major morbidities such as uterine rupture, hysterectomy, placenta accreta, and other placenta complications. The neonatal outcome measure includes neonatal morbidity (e.g., intensive care nursery admission and academia) and neonatal mortality.

FINDINGS OF THE STUDY:

A total of 71 patients had a history of one LSCS. Out of those, 70 were suitable for TOLAC. One was excluded as she had major placenta previa. Nine mothers chose ERCS after counselling. Six patients had ERCS by maternal request, one with an ovarian cyst, one with oligohydramnios with suspected cephalopelvic disproportion, and lastly, suspected macrosomia, while 61 patients had TOLAC. Regarding age distribution, a maximum number of patients were in the 30-34 age range (21/61) followed closely by 25-29 (18/61) and 35-39 (13/61). There were six patients in the 20–24-year age range, two in >40 years old, and only one patient was 20 years old. In terms of success rate, 37 patients had a normal vaginal delivery and one had a vacuum delivery, while 23 required LSCS (37.7%). Therefore, the total success rate of VBAC was (38/61) 62.3%.

Table 1. Gravida and mode of Delivery for patients with previous one LSCS

Gravida	Normal/ vacuum	Urgent CS	Total
2	9 (45%)	11 (55%)	20
3	13 (72%)	5 (28%)	18
4	7 (78%)	2 (22%)	9
5	4 (80%)	1 (20%)	5
6	1 (50%)	1 (50%)	2
7	2 (67%)	1 (33%)	3
8	1 (50%)	1 (50%)	2
9	-	1 (100%)	1
10	1 (100%)	-	1
Total	38	23	61

Regarding the gestational age, most patients (50/61, 82%) delivered between 37- 41 weeks gestation. There were 11 preterm deliveries (18%). Given the BMI, all patients with BMI >35 and 18 needed LSCS. Most patients with a BMI of 18 to 30 are delivered vaginally. (RR-2.9, p -0.63)

Regarding the indication of previous surgery and success rate, it was noted that two patients with previous LSCS due to CPD had 100% success. Similarly, one patient with previous LSCS due to abruption of the placenta and another one who had CS due to the big baby also had normal deliveries (100%). The majority of patients who had previous LSCS due to placenta previa (8/9) had normal deliveries this time (89%). It is closely followed by the previous LSCS due to an abnormal lie (10/12, 83%). A notable number of patients (9/15, 60%) with previous LSCS failed to progress, and half of the patients (50%) with presumed FD ended up with repeat LSCS in the index pregnancy. Those 3 patients whose previous LSCS was due to twins, a prolonged second stage, and a retroviral infection needed urgent LSCS this time.

In those who had previous VBAC, a significant number of them had successful vaginal deliveries this time (20/24, 83.3%) (P-value 0.01 and OD 0.34). For those without a previous VBAC, it was about 50%.

The majority of patients who had successful VBACs (27/39, 69%) had inter-pregnancy intervals was >2 years. There was only a 50% success rate (11/22) among those whose intervals between the pregnancies were <2 years. 22/61 patients needed induction of labour (IOL).

Of patients who received prostaglandin, 7 needed artificial rupture of membrane (ARM) and syntocinon infusion, and the majority (13/22) needed a combination. Successful VBAC was noted in 68% (15/22) of those who needed IOL and 61% (24/39) who went into labour spontaneously.

Figure 1: Cervical dilatation on admission and success of VBAC

Table 2: Neonatal admissions for mothers with previous LSCS who tried VBAC

No	Identification	Mode of Delivery	Diagnosis	Days
1	27, G2, full term	VBAC, 3.6 kg	Meconium-stained liquor	1
2	28, G2 31+4 weeks	VBAC, 2.1 kg	Prematurity and Hyaline Membrane Disease (HMD)	29
3	31, G3 full term	VBAC- vacuum, 3.4 kg	Transient Tachypnoea of Newborn (TTN)	3
4	33, G6 full term	Emergency LSCS for Fetal Distress (pH-7.343), 3.2 kg	Pulmonary Hypertension 2* Meconium Aspiration Syndrome (MAS)	14
5	25, G2 full term	EmergencyLSCS for failure to progress, 3.7 kg	Cleft lip for observation	7
6	35, G4 full term	EmergencyLSCS for Fetal Distress.2.9 kg	Observation-photo therapy	1
7	28, G2 full term	EmergencyLSCS for Cephalopelvic Disproportion, 3.4 kg	Observation	1
8	24, G2P2 34+4 weeks (Retroviral infection)	EmergencyLSCS for PPROM 2.4 kg	Observation	4

When analyzing the indications for current LSCS, seven mothers needed a CS given the presumed foetal distress, followed by failed IOL, failure to progress, and suspected CPD for three patients in each group. Other indications were maternal request in labour (2), prolonged latent phase (2), big baby and maternal request (1), big baby and suspected CPD (1), and lastly, retroviral infection and PPROM (1).

Maternal complications were noted in 4 patients (6.6%) among trials in the VBAC group. Most maternal complications occurred in those who needed urgent LSCS; two patients who underwent LSCS had minor postpartum haemorrhage (PPH), one had uterine scar rupture, and the last had a retained placenta. Uterine scar rupture occurred in a 24-year-old, gravida 2, who had a previous CS for a twin pregnancy and a retroviral infection 18 months ago. She came in with preterm prelabour rupture of membrane (PPROM) at 34 weeks, and urgent LSCS was done immediately for suspected scar rupture, which was confirmed intra-operatively. One of the successful VBAC groups had retained placenta, requiring manual removal of placenta (MRP).In the ERCS group, one mother who had minor placenta previa experienced major PPH and needed a blood transfusion.

In the VBAC group, there were a total of 8/61, and 13.1% of babies were admitted to the Special Care Baby Unit (SCBU). 3 babies admitted to SCBU were born through normal vaginal deliveries: 1 had meconium-stained liquor, 1 due to prematurity and Hyaline Membrane Disease (HMD), and 1 had Transient Tachypnea of the Newborn (TTN). A baby who was premature and had TTN stayed in SCBU for 29 days, but the other two babies were admitted for 3 days. The rest (5/8) were born through an emergency LSCS; only one baby delivered by emergency LSCS for foetal distress stayed in SCBU for 14 days for pulmonary hypertension (PH) secondary to meconium aspiration syndrome (MAS), but the cord pH is 7.343. Three others were kept for observation and one for cleft lip. In the ERCS group, 2 out of 9 babies were admitted to SCBU for TTN for less than 3 days, with a neonatal admission rate of 20.2%.

Hospital stays for patients with a successful outcome were 1.6 days, and for those who ended up with LSCS were 4.1 days. For ERCS, the average stay was 4.7 days.

DISCUSSION:

According to the new VBAC guideline from ACOG (the American Congress of Obstetricians and Gynaecologists), it’s estimated that 60–80% of appropriate candidates who attempt VBAC will be successful.¹ As per the RCOG green-top guideline, women considering their options for birth after a single previous caesarean should be informed that, overall, the chances of a successful planned VBAC are 72–76%. ² The success rate of VBAC in this study is 63%, which is slightly lower than the RCOG guideline but within the range of the new ACOG VBAC guidelines.

Previous vaginal birth, particularly previous VBACs, is the single best predictor for successful VBACs and is associated with an approximately 87–90% success rate.^3,4,5 In this study, 83% of patients with previous successful VBAC had a successful vaginal delivery as compared with 51% who did not have a history of previous successful VBAC (83% vs 51% - OD-0.34, OD 0.34, P 0.01). Therefore, this shows a significant association between previous successful VBACs and successful VBACs. Risk factors for unsuccessful VBAC are induced labour, BMI > 30, and previous CS for dystocia. When all these factors are present, a successful VBAC is achieved in only 40% of cases. ^{6,
7, 8}

There were 11 preterm deliveries (18.03%) in our study, which is slightly higher than the preterm delivery rate of the general population of 11% (WHO 2020). 68% of induced patients and 61% of patients with spontaneous labour delivered normally, and IOL was not associated with a reduced success rate in this study, although others stated that IOL is associated with a lower success rate. In addition, all 4 patients whose BMI was >35 were delivered by urgent CS (RR 2.9, p -0.63), and most patients with BMIs 18 to 30 were delivered vaginally. We can see there is an association between high BMI and a higher risk of failed VBAC, but it did not reach a statistically significant level. All two patients with previous indications of dystocia delivered normally, and there was no association between the previous dystocia and the successful outcome. If the previous indication of CS is placenta previa and abnormal lying, there is a high success rate in this study.

There are numerous other factors associated with a decreased likelihood of success, including: VBAC at or after 41 weeks of gestation, birth weight >4000 g, no epidural anaesthesia, previous preterm caesarean birth, cervical dilatation 4 cm at admission, 2 years from a previous caesarean birth, advanced maternal age, non-white ethnicity, short stature, and a male infant.

In the index study, 57% of the patients with cervical dilatation <4 cm on admission and 92% with >4 cm had a successful VBAC (p 0.02, RR 0.19, CI 0.29–1.3055). A significant association between a successful VBAC and cervical dilatation of >4 cm on admission was noted during this study.

All babies whose birth weight was less than 2.5 kg and 66% of babies in the range of 2.5 to 3.5 kg were born through normal vaginal delivery. But only 4/12 babies (34%) who were >3.5 kg were delivered vaginally. Therefore, higher birth weight and a failed VBAC were associated.

Taking epidural anaesthesia during labour is not a routine practice in RIPAS Hospital, and therefore, we cannot draw a conclusion regarding epidural use in labour. The majority of successful VBACs (69%) fell in those whose interpregnancy intervals were >2 years than those whose intervals were 2 years. Therefore, it is advisable to defer pregnancy for at least 2 years after LSCS. This finding was supported by RCOG Guideline ¹ but not by Wu Y et al. (9). 50% of patients who were >40 years old had a successful VBAC as compared to 68% of patients who were >30–40 years old. Advanced maternal age is associated with a high risk of unsuccessful VBAC, and this finding was agreed upon by both the RCOG and Australian studies. ^{9, 10, 11}

In this study, there was one uterine scar rupture among the group of women who were selected to undergo VBAC. In her case, she came with PPROM and was decided for an urgent cesarean section instead. There was no scar trial, and uterine scar rupture was confirmed intraoperatively. Fortunately, both mother and baby had a good outcome.

The absolute risk of adverse outcomes for both planned VBACs and ERCS is small. The benefits to a woman of having a planned VBAC are generally related to vaginal birth, as this typically has the lowest morbidity. Most maternal morbidity related to a planned VBAC occurs if an emergency CS (as opposed to an ERCS11) is required. Consequently, a woman’s risk of morbidity is closely related to her probability of VBAC. ¹²

Three maternal complications occurred in the failed VBAC group: two patients had minor PPH and one had uterine scar rupture; in the successful group, one had a retained placenta and needed MRP. One major PPH was noted in the ERCS group. Therefore, maternal complications were more common in the failed VBAC group.

The neonatal admission rate was slightly lower in the trial of the VBAC group (13.1%), but two babies were admitted for more than 14 days: one was prematurity and another was MAS. 2/10 (20%) babies from ERCS were admitted for TTN, but they stayed less than 3 days. Therefore, there were no serious neonatal complications in both groups of patients.

The number of days of hospital stay was definitely shorter in patients who had successful VBACs (1.6) compared to those with failed VBACs and who underwent emergency LSCS as well as those with elective LSCS (4.3 days). A study done by Lai concluded that days spent in the hospital in the emergency CS group were 6.9, the vaginal birth group was 2.7, and the elective CS group was 6, which is similar to our study. ¹³

CONCLUSION:

In this current study, authors conclude 62.3% of patients had a successful VBAC, and there was no evidence of an increase in serious complications with a VBAC compared to a vaginal birth in nulliparous women. In those who had previous VBACs, cervical dilatation of >4 cm at the time of admission is a significant factor for a successful VBAC. There are often differences in VBAC success rates between centers and published studies, and even though this study was done a few years ago, there was not much change in terms of success and factors associated with success rate. This study provides important additional information to the pregnant lady with a previous LSCS scar at RIPAS Hospital for counselling about the trial of VBAC and ERCS regarding success rate and complications and will help them decide on their mode of delivery. Actually, the only way to eliminate the risks associated with each of these two options is to obviate the need for both of them by avoiding the primary caesarean that permanently scars the uterine wall.

DISCLOSURE OF INTERESTS:

None.

CONTRIBUTION TO AUTHORSHIP:

Soe, N.N: Project development, data collection, manuscript writing, and editing

Caroline. T.C.P: Manuscript writing and editing

Mon Mon Yee: Manuscript writing and editing

Hlaing. M.T: Data analysis

REFERENCES:

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10. The Royal Australian and New Zealand College of Obstetricians and Gynaecologists. Birth after previous caesarean section. College Statement C-Obs 38.].2019 http://www.ranzcog.edu.au

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https://www.health.qld.gov.au/__data/assets/pdf_file/0022/140836/g-vbac.pdf

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Received on 12.05.2023 Modified on 08.06.2023

Research J. Pharm. and Tech 2023; 16(7):3353-3357.

DOI: 10.52711/0974-360X.2023.00554