Spina bifida in pregnancy: A review of the evidence for preconception, antenatal, intrapartum and postpartum care

Short abstract

Women with spina bifida in pregnancy require complex multi-disciplinary management. Most women have uncomplicated pregnancies; however, complications are more frequent than in ‘low risk’ pregnancies. Careful antenatal planning and management of the complications can optimise outcome. There are currently no guidelines on the management of pregnant women with spina bifida, but there is a growing body of evidence from case reports and series examining the antenatal and postnatal course of these women. In this review, we examine the available literature and provide a framework on the prenatal counselling, antenatal, intrapartum and postnatal management of pregnant women with spina bifida.

Introduction

The term ‘spina bifida’ (SB) refers to a spectrum of disease resulting from failure of the caudal neural tube to fuse in the developing embryo. It is subdivided into open, occult (closed) and dysraphism.

Open SB (spina bifida cystica) refers to versions of caudal neural tube defect (NTD) where the spinal cord and/or meninges herniate through. The two forms are myelomeningocele and meningocele. Lesions are usually in the lumbar and sacral areas, with higher lesions causing more severe disability and worse cognitive function.¹

Myelomeningocele is the most severe and common form of SB cystica. It is often associated, in infancy or childhood, with downward displacement of the medulla, fourth ventricle and cerebellum through the foramen magnum and into the cervical spinal canal (Arnold-Chiari malformation type II), and with hydrocephalus. Those affected will most likely require ventriculo-peritoneal shunt insertion to treat secondary hydrocephalus.² Myelomeningocele can result in lifelong problems with mobility, sensation, urinary and bowel continence.³ Advancing fetal surgery techniques mean this abnormality can now be repaired in utero, with good results.⁴

SB occulta is a milder form of NTD, which often remains undetected. The vertebral arch fails to fuse in the midline, but the spinal cord does not protrude through the defect and there are no external lesions. SB occulta is a benign condition and there are no neurological manifestations.¹

Dysraphism involves closed skin-covered lesions, in which the cord is tethered. It can cause neurological and urological disability.

In 1995–1999, the UK incidence of SB was 0.8/10,000 live births.⁵ This followed the introduction of prenatal/antenatal folic acid supplementation, and is demonstrated by the rapid drop in rates from 11.8/10,000 live births in 1975–1979.⁵

The level of the spinal defect has a strong influence on long-term survival rates. For infants born between 1963 and 1971, survival rate to age 40 years was 17% in those born with a high sensory level (above T11) and 61% in those born with a low sensory level (below L3).⁶ Advances in surgical techniques to repair defects associated with SB means that more patients are now surviving to childbearing age and, as there is no reported reduction in their fertility, there is an increasing number who potentially could become pregnant.

Although there are currently no guidelines on the management of pregnant women with SB, there is a growing body of evidence from case reports and series examining the antenatal and postnatal course of these women. In this review we examine the available literature and provide advice on prenatal counselling and the antenatal, intrapartum and postnatal management of pregnant women with SB.

Pre-conception counselling

Pre-conception counselling of women with SB is strongly recommended for those of, or approaching, child-bearing age.³ A summary of suggested pre-conception management can be found in Table 1. Hydrocephalus in these patients can result in precocious puberty resulting in earlier menarche and ability to conceive.³ Pre-conception reviews should include optimisation of medications and tight control of secondary conditions associated with SB. Commonly associated conditions include urological and bowel abnormalities, hypertension, kyphoscoliosis, cerebrospinal fluid (CSF) shunts, epilepsy and orthopaedic issues.

Table 1.

Pre-conception counselling.

Genetic counselling	Multi-factorial aetiology
	Recurrence risk is 1–5% if one parent is affected and 15% if both parents are affected.
Folic acid	5 mg daily for women who have previously had an affected baby or couples with a personal history of spina bifida.
	Should be started a minimum of three months pre-conception and continued until 12 weeks of pregnancy.
Maternal obesity	More common in spina bifida population and causes increased risk of fetal spina bifida as well as other complications in pregnancy.
	Advised on optimising weight pre-conception.
Medication review	Review of all prescription and over-the-counter medications and where possible, stop or change any teratogens prior to pregnancy.
Epilepsy	Seizure frequency should be optimised prior to pregnancy and women should ideally be on AED monotherapy on the lowest effective dose.

AED: anti-epileptic drug.

The possibility of a fetus having a NTD and risk reduction methods should also be discussed. A family history of a neural tube defect is a significant risk factor for the development of similar fetal malformations. If one parent is affected by SB, the risk of fetal SB is 1–5%; if both parents are affected, the risk increases to 15%.⁶

Genetic counselling

SB is thought to be multi-factorial in origin, with evidence of contributions from environmental factors and multiple genes. The most commonly attributed genes are those involved in folate homocysteine metabolism such as those coding for 5, 10-methylenetetrahydrofolate reductase (MTHFR), methionine synthase (MTR), methionine synthase reductase (MTRR) and methylenetetrahydrofolate dehydrogenase/methylenetetrahydrofolate cyclohydrolase/formyltetrahydrofolate synthetase (MTHFD1). Whether the risk of SB is related to interactions between these genes, presence of the gene on the maternal or fetal genome, or interaction of these genes with environmental factors, is unclear.⁷ As the aetiology is multi-factorial, it is not possible to accurately predict the risk of fetal SB pre-conceptionally from gene panels.⁸

Folic acid

It is internationally recognised that the daily intake of folic acid pre-conceptionally and throughout the first trimester of pregnancy significantly reduces the risk of fetal NTDs. In a multi-centre randomised control trial, the Medical Research Council demonstrated a 72% reduction (relative risk 0.28, 95% confidence interval 0.12–0.71) in cases of NTD in women who had previously had an affected fetus, when taking 4 mg folic acid supplements daily.⁹ A later prospective, multi-centre trial showed decreasing rates of NTD in all women, by increasing intakes (dietary and supplementary vitamins) of folic acid. Maximum effect (77% reduction) was seen in the group taking >1200 folate equivalents per day (equivalent to 1.2 mg dietary intake or 0.6 mg supplements).¹⁰

The National Institute for Health and Care Excellence (NICE) UK recommends daily supplements of 5 mg folic acid for all women at high risk of fetal SB. This includes couples where one or both partners have SB, women who have had a previous pregnancy affected with a NTD, couples who have family history of NTDs, women with pre-existing diabetes mellitus and women taking folate inhibitors. A lower dose of 0.4 mg is advised to be taken by all women who may become pregnant, regardless of whether pregnancy is planned imminently, and continued until 12 weeks of pregnancy.¹¹

Obesity

Female adults with SB are 50% more likely to be obese than the general population.¹² Those with abnormalities at the sacral level have the highest risk of obesity, possibly due to the increased risk of urinary incontinence and resultant apprehension of performing physical activity.¹² Antenatal and intrapartum complications are increased 2–3 fold in obesity¹³ and the risk of fetal spinal bifida is increased by a factor of 1.9–3.5.^14,15 Support should be provided to reduce weight prior to pregnancy, within the limits of exercise tolerance and mobility. This includes providing advice on lifestyle and monitoring of weight/body mass index (BMI) regularly.¹³

Epilepsy

Approximately 12% of people with SB have epilepsy complicating their condition.¹⁶ Pre-conception, epilepsy management should be targeted toward optimising seizure control with the fewest and lowest dose of anti-epileptic drugs (AEDs) and on the commencement of 5 mg folic acid supplements. Where possible, consideration should be made into changing anti-epileptic medications to those known to have less teratogenic effects. These decisions should be made between the woman and her epilepsy specialist. The risks of discontinuing epilepsy medications on seizure control and sudden unexpected death in epilepsy (SUDEP) should be discussed.¹⁷

Medication review

Women with SB may be taking a range of medications pre-conceptionally. These include analgesics, AEDs for seizure control, laxatives for chronic constipation, anti-cholinergics for bladder continence and antibiotics for recurrent urinary tract infection (UTI) prophylaxis/treatment. These medications should be reviewed in conjunction with the prescribing specialist prior to conception. Care should be taken to potentially alter teratogenic drugs (e.g. sodium valproate, carbamazepine) or those drugs that affect folate metabolism (e.g. trimethoprim in the first trimester). Potential long-term effects on neonatal & child development by AEDs should also be discussed.^18,19

Diabetes

Pre-existing diabetes mellitus is an independent risk factor for developing fetal malformations of the central nervous system. This risk appears to be directly proportional to glucose levels in the first trimester.²⁰ Diabetic women with SB, who are already high risk for fetal NTDs, should have their glycaemic control optimised pre-conception.

Antenatal management

Women with SB can be categorised according to the form and severity of their SB. Women with milder forms can still be considered low risk for pregnancy. Those with greater disability will require multi-disciplinary input including from obstetricians, neurologists, urologists and anaesthetists. We suggest the following management strategy for these patients (Table 2).

Table 2.

Suggested antenatal management.

Antenatal setting	Women with mild disease can often be managed with shared care between obstetricians and midwives.
	Women with moderate or severe disease will require multi-disciplinary input from obstetricians, midwives, neurologists, urologists, anaesthetists etc.
Screening	Screening for fetal neural tube defects on the anomaly scan by the fetal medicine unit should be offered to all women.
Urinary problems	Women may have under or overactive bladder patterns. Areflexic bladders can worsen in pregnancy and are more prone to infection.
	Perform serum urea and electrolytes, renal ultrasound scan and midstream urine culture at booking.
	Oxybutynin is thought to be safe in pregnancy for detrusor over-activity.
	Clean intermittent self-catheterisation may be offered to women with incomplete bladder emptying.
Hypertension	More common in women with spina bifida. Vigilance therefore required with routine screening.
Venous thromboembolism (VTE)	Reduced mobility is a risk factor for VTE and women should be undergo a VTE risk assessment to ensure other risk factors are considered.
Orthopaedic issues	Longstanding limb contractures can cause pelvic obliquity, requiring assessment for suitable mode of delivery.
	Scoliosis should be assessed in conjunction with anaesthetic colleagues in case regional anaesthesia is required.
Cerebrospinal fluid shunts	Ventriculo-peritoneal shunts in particular can become problematic due to displacement from a gravid uterus.
	Symptoms of hydrocephalus should be investigated with cranial magnetic resonance imaging. Monitoring of shunts by neurosurgeons is recommended.
Seizure control	9–12% patients have epilepsy. This should be managed according to normal epilepsy in pregnancy protocols.
Kyphoscoliosis	Women with SB and kyphoscoliosis require close monitoring with pulmonary function tests, pulmonary vascular pressures and echocardiography. In cases where kyphoscoliosis is severe, non-invasive positive pressure ventilation may be used to treat type 2 respiratory failure or nocturnal hypoventilation, and improve exercise tolerance.

AEDs: anti-epileptic drugs; SB: spina bifida.

Screening for NTDs

In view of the increased risk of fetal SB, in a mother with SB, particular attention should be made to exclude fetal SB through screening. Traditionally fetal SB is screened for at the 20-week anomaly scan, which has a detection rate of over 90%.²¹ Ultrasound examination can detect the level of lesion, type of SB and other associated cranial abnormalities including Arnold-Chiari malformation and ventriculomegaly.²² There is an increasing body of evidence for accurate diagnosis of SB in the first trimester, and patients already affected with SB should be referred to fetal medicine centres.²³

Median alpha-fetoprotein (AFP) level measured in the quadruple screening blood test is higher in pregnancies with open SB than in unaffected pregnancies. Bernard et al. showed that raised AFP levels in conjunction with biparietal diameter and β-human chorionic gonadotrophin (hCG) can enable earlier detection of open SB in two-thirds of affected pregnancies²⁴; however, these methods have become outdated and have been superseded by ultrasound. Counselling when an abnormality is detected should include level of defect, size, presence of hydrocephalus and potential surgical correction of the fetus or neonate. This discussion should be conducted in conjunction with the paediatric team. With regard to fetal SB surgery, the Management of Myelomeningocele Study (MOMS) trial showed benefit of in-utero correction of spina bifida, reducing need for shunt insertion in infancy.⁴ Discussion should also include offer of pregnancy termination and counselling that the full extent of disease may not be known until birth.²²

Urological and bowel issues

Urological abnormalities in patients with SB can be complex and are best managed in conjunction with a urologist.

There are three main bladder abnormalities associated with SB:

• Hyperreflexia (un-inhibitable contraction)

• Areflexia (absence of contractions)

• Mixed dysfunction.

The urological sphincter can also be affected and be either:

• Dyssynergic (no coordination between bladder and sphincter function)

• Non-functional

• Synergic (bladder and sphincter function coordinated).²⁵

The most common pattern in SB is areflexic bladder with non-functional sphincter which can lead to damage of the upper renal tract due to high backflow pressure from the bladder. Detrusor overactivity (hyper reflexia) can lead to urinary incontinence. Bladder stasis (areflexia) combined with vesico-ureteric reflux can increase the propensity for UTIs and renal damage.³

Pregnancy can exacerbate urinary symptoms. Production of prostaglandin E2 decreases ureteric peristalsis, which increases hypomotility and distension. The increase in progesterone and oestrogen causes hypertrophic changes exacerbating hypomotility. The gravid uterus can cause mechanical obstruction worsening ureteric distension and hydronephrosis.²⁶

Pregnant women with SB should have a full assessment of renal function early in pregnancy. This should include urea, creatinine and electrolytes, renal tract ultrasound and mid stream urine culture (MSUC).³ Subsequent antenatal visits should include regular MSUC with sensitivities to facilitate prompt treatment of infection avoid antibiotic resistance. Women should be questioned regarding symptoms of loin pain, dysuria and haematuria and if present should be promptly investigated.

Congenital renal and genitourinary abnormalities can result in women undergoing urinary diversion procedures preceding pregnancy, with an ileal conduit being the mainstay of treatment for incomplete bladder emptying prior to 1980.²⁷ A case series by Arata et al., showed that most ileal conduits functioned well in pregnancy with very few undergoing leakage, stenosis or ulceration. However, a high degree of suspicion should be maintained for obstruction or displacement of conduits during the antenatal period.²⁷

Case reports of women with SB and augmentation cystoplasty in pregnancy demonstrate that aside from encountering the above problems of recurrent UTIs and hydronephrosis, these patients are also at increased risk of metabolic complications such as vitamin B12 deficiency, hypokalaemic hyperchloraemic metabolic acidosis, hypocalcaemia and hypomagnesaemia. Serum blood levels of the above should be closely monitored in pregnancy.²⁸

Presently, women with incomplete bladder emptying and sphincter overactivity are offered intermittent catheterisation. This method may not be suitable for all and is associated with UTIs.^3,27 Those with indwelling catheters (urethral or suprapubic) are at a higher risk of bladder stones. Women with repeated catheter blockages or haematuria should be referred for cystoscopy.²⁹

Urinary incontinence associated with detrusor overactivity may be treated with anti-cholinergics, namely oxybutynin which is thought to be safe in pregnancy.³ Anti-cholinergics may exacerbate constipation and thereby also increase the risk of UTI in pregnancy. In cases of detrusor overactivity where anti-cholinergics are contraindicated or ineffective, botulinum toxin bladder wall injections may be used. Women should be aware that a catherisation regime may be required after such a treatment.²⁹

Patients with asymptomatic bacteriuria should be treated with appropriate antibiotics to prevent pyelonephritis.³ Evidence has shown that recurrent urinary infections can lead to fetal growth restriction and preterm delivery.³⁰ Antibiotic prophylaxis should be considered in these cases to also avoid upper renal tract damage.

Constipation can be common in patients with SB due to autonomic dysfunction. This can be treated conservatively by increasing oral fluid intake and dietary fibre. Appropriate laxatives such as glycerine suppositories can be used to relieve more persistent symptoms.³

Hypertension

Patients with SB are more susceptible to hypertension and at a younger age. Stepanczuk et al. showed that for age-matched controls women with SB aged 30–39 had a 6% higher risk of hypertension.³¹ The underlying pathophysiology is not completely understood but may be due to longstanding renal damage. Additional risk factors include ambulatory status, smoking, age and BMI.³¹ Women with raised blood pressure (above 140/90 mm Hg) at booking should have a baseline renal function and proteincreatinine ratio measured. If blood pressure is greater than 150/100 mm Hg, treatment should be considered. Those with underlying renal dysfunction should aim for blood pressure less than 140/90 mm Hg as indicated by the NICE Hypertension in Pregnancy guidance.³² Low-dose aspirin can be started (from 12 weeks antenatally) in those with pre-existing hypertension, to reduce the risk of pre-eclampsia, whilst uterine artery Dopplers performed at 20–24 weeks can aid pre-eclampsia risk stratification. First-line anti-hypertensive medications in an SB-affected pregnancy are the same as in non-SB pregnancy.³²

Venous thromboembolism prophylaxis

Whilst specific data regarding risk of venous thromboembolism (VTE) in immobile pregnant patients are lacking, there is evidence which demonstrates that immobile/paralysed limbs are at greater risk of developing deep vein thrombosis.³³

The Royal College of Obstetricians and Gynaecologists (RCOG) UK recommends all pregnant women should be assessed for risk of VTE antenatally. Thromboprophylaxis should be commenced in those who are immobile with four risk factors in total from first trimester or three in total from 28 weeks of gestation.³⁴ Since mobility for women with SB can vary throughout pregnancy, risk assessment should continue throughout the antenatal and postnatal period.²⁷

Orthopaedic issues and mobility

SB can lead to a variety of orthopaedic problems including hip, knee, foot and rotational deformities. Lower limb contractures are common; patients are often treated with orthoses from childhood and require extensive orthopaedic input.³⁵ The degree of mobility in patients with SB depends on the level of the defect: the higher the lesion the worse the degree of disability. Those with lesions at L4 and L5 are usually ambulatory, lesions above L3 are usually non-ambulatory.³⁵ In a case series by Arata et al., immobility did not prevent pregnancy – 4 out of the 17 women with SB were wheelchair-dependent.

Long-standing contractures can lead to pelvic obliquity which can affect women’s reproductive anatomy by alteration of the pelvic floor.³⁶ Careful assessment is necessary when considering mode of delivery due to anticipated difficulty with vaginal examinations and vaginal delivery which may necessitate instrumental intervention. Wheelchair dependence led to more frequent hospital admissions and an increased caesarean section rate.²⁷

Increased care is required to prevent pressure sore development, exacerbated by weight gain in pregnancy. Mobility can deteriorate in pregnancy and previously mobile women may require wheelchair assistance. Arata et al. also showed that mobility does return to pre-pregnancy levels postnatally in most cases.²⁷ Additionally, up to 50% of women with SB have some degree of scoliosis which can affect placement of regional anaesthesia (see anaesthetic review below).

Kyphoscoliosis and cardiorespiratory complications

Kyphoscoliosis is a recognised secondary condition of SB, which can cause chronic hypoxemia due to hypoventilation. This can lead to pulmonary vasoconstriction and cause right ventricular remodelling with hypertrophy and dilatation. This can result in right heart failure and pulmonary hypertension. In pregnancy, the gravid uterus can decrease diaphragmatic activity and spinal curvature can become more exaggerated, worsening pre-existing cardiorespiratory abnormalities.³⁶ Women with kyphoscoliosis and SB should be managed in conjunction with respiratory physicians.

In pregnancy, kyphoscoliosis may prevent the necessary increase in cardiac output required for pregnancy, leading to an increased load on the right ventricle and possible pulmonary hypertension.³⁶ Women with SB and kyphoscoliosis require close monitoring with pulmonary function tests, pulmonary vascular pressures and echocardiography. Those with pre-existing pulmonary hypertension have less favourable outcomes in pregnancy.³⁷ The forced vital capacity can decrease further in pregnancy leading to reduced exercise tolerance, fatigue and nocturnal hypoxia. It is postulated that a forced vital capacity of around 1L is required for a successful pregnancy, although women with worse restrictive lung function have undertaken successful pregnancy. In cases where kyphoscoliosis is severe, non-invasive positive pressure ventilation may be used to correct nocturnal hypoventilation and improve exercise tolerance.³⁸

Growth scans at 3–4 weekly intervals from 28 weeks are required due to potential compression of the fetus and growth restriction.² There may also be an increased risk of a fetal malpresentation. A case series of 22 women and 34 pregnancies with kyphoscoliosis in pregnancy by Chopra et al. showed a higher risk of caesarean section.³⁹

Latex allergy

Compared to the general population, SB patients are known to be at higher risk of developing latex sensitisation and allergies. The percentage of SB patients sensitised to latex is approximately 40–48%, with 15–18% being truly allergic to natural rubber latex.^40,41

It is hypothesised that this may be secondary to the repeated surgeries SB patients are subjected to in early life. It is therefore important to ask all SB patients regarding latex allergy in the antenatal period and consider this possibility when choosing gloves, catheters and other latex products.

CSF shunts

Hydrocephalus is present in approximately 90% of patients with myelomeningocele, most of whom have CSF shunts.⁴² CSF shunts are not a contraindication to pregnancy and those with successfully managed hydrocephalus can have a safe pregnancy and birth.⁴³

Previous studies have shown that most shunt-related problems in pregnancy were associated with ventriculo-peritoneal shunts, due to increasing size of the gravid uterus.⁴⁴ Liakos et al. reported on 70 women with CSF shunts in pregnancy, with seven of these women requiring shunt revision.⁴³ Less severe complications included seizures, abdominal pain and headaches. These complications were managed conservatively and resolved postnatally.³⁶ A further case series by Bradley et al. reported on 37 women with ventriculo-peritoneal shunts, of which 84% had no shunt malfunctions or revisions.⁴⁵

Close monitoring of shunt function and position, with guidance from the neurosurgical team, is required throughout pregnancy. Symptoms of hydrocephalus can present from early pregnancy and include headache, nausea and vomiting. Unfortunately, these can be mistaken for normal symptoms of early pregnancy. Women presenting with severe headache and neurological signs should have an magnetic resonance imaging (MRI) scan to determine ventricular size and investigation for shunt malfunction.⁴⁴

Shunt malfunction can be dealt with conservatively by manual aspiration of CSF. Women with severe shunt malfunction may require preterm delivery with caesarean section and shunt revision.² Women with functioning shunts or mild shunt dysfunction can have vaginal deliveries with appropriate monitoring in labour, only requiring caesarean section for obstetric reasons.⁴⁵ Caesarean section is associated with increased risk of shunt infection and adhesion formation can lead to shunt obstruction at the distal end of the catheter.⁴⁴ There is no clear evidence regarding antibiotic prophylaxis in these patients.

There are varying opinions on shortening the length of the second stage of labour in patients with CSF shunts. Previous reports advocated a shortened second stage (by elective instrumental delivery) to avoid raised intracranial pressure.⁴⁶ Advances in shunts with unidirectional flow valves have made this somewhat redundant.⁴⁴

Postnatal shunt malfunction has been reported, even in patients with an uneventful antenatal and intrapartum period. In these cases, shunt revision may be required.⁴⁵

Epilepsy

Approximately 12% of patients with SB have active epilepsy.¹⁶ These women should be managed under joint Neurology and Obstetric care. Women who have had a seizure within one year prior to conception should be more closely monitored. Around 60% of women will not have seizure deterioration during their pregnancy. Counselling regarding sudden unexplained death in epilepsy and possible increase in frequency of seizures in 30% of women should occur. Women should also be counselled that there is increased risk to the fetus if seizure frequency is not controlled.¹⁷

Women with epilepsy should take preconception folic acid 5 mg and continue until 12 completed weeks of pregnancy.

Strict seizure control in pregnancy should be achieved with an appropriate AED, preferably aiming for monotherapy at the lowest dose. Pregnancy can cause changes in plasma concentrations, for example the protein-bound drug lamotrigine can a fall by 70%.⁴⁷ There is no evidence to justify routine monitoring of serum levels of AEDs in but this may be required on an individualised basis.¹⁷

Women on AEDs will require fetal echocardiography at 20–24 weeks in addition to their detailed anomaly scan at 20 weeks.¹⁷ Women should be counselled that fetal exposure to AEDs in utero increases the risk of a small for gestational age fetus by 3.5 fold. Women on AEDs should therefore have serial growth scans at 28, 32 and 36 weeks.⁴⁸

Delivery should take place on a consultant-led obstetric unit in case of seizures in labour.⁴⁷ Those with increased seizure frequency close to delivery may require a long-acting benzodiazepine such as clobazam.¹⁷ Seizures in the intrapartum and peripartum period can be reduced by effective analgesia, hydration and sleep. Safety principles regarding care of the neonate and discussion regarding an increased risk of peripartum seizures ought to occur. Women should have a family member or friend with them at all times if cared for in a side room.¹⁷

There are no contraindications to breastfeeding on AEDs and women with epilepsy should be encouraged to breastfeed.⁴⁷

Anaesthetic review

All parturients with SB cystica, with SB occulta and neurological symptoms or suspicion of tethered cord should be referred to the obstetric anaesthesia team as early as possible. This will enable sufficient time to assess, investigate (an MRI is often indicated), obtain previous records, consult the neurology team if needed and discuss options for labour analgesia and caesarean section as early as possible. These patients may be medically complex, therefore early anaesthetic assessment and optimisation are vital. Referral to specialist centres for delivery may be warranted. There should be an established anaesthetic plan, written in advance. A consultant anaesthetist should be informed when the patient presents in labour or for elective caesarean section.

Labour, epidural analgesia and anaesthesia for caesarean section is usually uncomplicated in SB occulta. However, a minority of these women may have spinal cord tethering or spinal dysraphism,⁴⁹ precluding the use of spinal techniques without prior MRI imaging, due to the risk of spinal cord injury.

In SB cystica, spinal anaesthesia is normally contraindicated due to risk of failure/patchy block and theoretical risk of spinal cord injury. Epidural analgesia is possible and mostly successful in case series.^50,51 There is, however, an increased risk of dural puncture due to abnormal supporting ligaments,^49,50 abnormal spread of anaesthetic⁵⁰ and technical difficulties in placing these (often due to kyphoscoliosis), which may be improved with the use of ultrasound. The use of ultrasound to accurately locate the midline and measure the depth of the epidural space is becoming more widespread and has also been used to diagnose occult SB.⁵¹ The epidural catheter is normally placed above the level of the lesion. This may result in insufficient perineal analgesia due to sacral segment sparing (poor caudal spread of local anaesthetic). In this case, a second epidural catheter can be placed below the level of the lesion⁵² or other regional nerve blockade adjuncts such as lumbar plexus or pudendal nerve blocks used.⁵³ This two-epidural technique has been used for caesarean section.

During general anaesthesia there is an associated increased risk of difficult intubation⁵⁴ and potential for perioperative respiratory problems with severe thoracic kyphoscoliosis. Patients may need postoperative non-invasive ventilation.

Intrapartum

Delivery on a consultant-led obstetric unit is imperative for complex patients with SB. Antenatal planning in conjunction with obstetricians, anaesthetists, neurologists and urologists allows for an individualised care plan for labour and delivery.⁴⁹ See Table 3 for a summary of suggested intrapartum management.

Table 3.

Suggested intrapartum management.

Epidural/spinal anaesthesia	Risk of spinal cord injury if spinal cord is tethered or compressed.
	Spina bifida cystica can result in patchy block.
	Increased risk of dural puncture, although the risk can be reduced by ultrasound guidance.
	Refer for an anaesthetic opinion antenatally. MRI may be required.
Mode of delivery	Those with urinary and bowel diversion procedures who require caesarean section for obstetric indication will need surgical input at delivery from colorectal and urology teams.
	Patients with fixed adduction deformities may require elective caesarean section. Problems encountered intrapartum are positioning for women who are non-ambulatory and those with fixed contractures.
	Women with neurological defects may warrant elective instrumental delivery if they are unable to actively bear down.
	Women should be catheterised to prevent bladder distension.

Women with urinary and bowel diversion procedures who require caesarean section for an obstetric indication will need surgical input at delivery from colorectal and urology teams.²⁸ This includes women with augmentation cystoplasty, who often have anatomical alterations from the bladder augmentation surgery. The gravid uterus can exacerbate these changes further.

Vaginal delivery is possible in SB,²⁷ although it may be contraindicated with some of the complicating conditions. Women with fixed adduction deformities may require elective caesarean section.²⁷ Women who are non-ambulatory and those with fixed contractures may encounter problems with positioning in labour.³⁶ Advice on physical aids in labour may be sought from occupational therapists. Spinal dysraphism can predispose to reduced bearing-down efforts in the second stage and increase the need for instrumental delivery.² The presence of a CSF shunt does not necessarily require shortening of the second stage.

There is more susceptibility to hypertensive episodes in labour and careful monitoring of blood pressure is required. Patients with kyphoscoliosis will necessitate additional monitoring of oxygen saturation and respiratory rate.⁵⁵

Appropriate bladder care is vital to reduce UTIs. Women should be catheterised to avoid bladder distension.²⁵ Adequate hydration and anti-embolism compression stockings are essential to reduce the risk of VTE.³⁴

Postnatal management

Although there is little evidence regarding postnatal care in women with SB, there are several points that can be drawn from antenatal and intrapartum care. These are summarised in Table 4.

Table 4.

Suggested postnatal management.

Venous thromboembolism	Perform a risk assessment of other factors and consider prolonging VTE prophylaxis in the presence of immobility.
Breastfeeding	Consider drug safety in accordance with a full repeated medication history.
	Positioning for breastfeeding might be difficult in the presence of kyphoscoliosis. Take advice from breastfeeding specialists.
Seizures	Usual epilepsy safety advice should be given to women at risk of seizures.
Contraception	No specific contraindications but oestrogen-containing preparations may be avoided if there is already an increased risk of VTE.

VTE: venous thromboembolism.

Arata et al. showed that most women with SB had an uncomplicated postpartum course although there were reports of UTI, worsening hypertension and postnatal shunt relapse.²⁷ Women with SB may require extended VTE prophylaxis in the postpartum period due to reduced mobility.³⁴

Breastfeeding may be problematic especially in women with kyphoscoliosis who have difficulties in positioning the neonate on the breast. Breastfeeding specialists may provide extra support to establish breastfeeding.³⁹

Women at risk of seizures should be advised caution when carrying their babies (for example, not to carry in arms downstairs) and if bathing the neonate when unattended by another person. A visit from an occupational therapist could assist in arranging their home to facilitate safer care.⁴⁷

Careful discussion should take place regarding contraception avoiding oestrogen-containing contraceptives in those who are at increased risk of VTE. Insertion of intrauterine devices may be particularly difficult in patients with fixed contractures.³

Discussion

Women with SB in pregnancy require complex multi-disciplinary management. Most women will have an uncomplicated antenatal, intrapartum and postnatal course; however, several complications may occur and some have serious consequences on both the mother and fetus. Careful planning of pregnancy with management of the complicated pregnancies at a tertiary centre can optimise outcome.

Declaration of conflicting interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship and/or publication of this article.

Guarantor

KS

Contributorship

Kenga Sivarajah developed the idea for this article. Kenga Sivarajah, Sophie Relph and Spyros Bakalis contributed equally to the writing of the article. Radha Sabaratnam contributed to the anaesthetic section. Kenga Sivarajah, Sophie Relph and Spyros Bakalis edited the article prior to publication.