From Breech to Brow - Case Study
by Thomas Ind MB BS MD MRCOG
St George Hospital, Kogarah, Sydney, Australia

Case of the Month - September 1998

Introduction

A fetal presentation is the lowest part of the fetus present in the pelvis or lower uterine segment. In over 95% of cases the presentation is a fully flexed vertex. Anything other than a fully flexed vertex is defined as a malpresentation. One of the most common malpresentations is a breech (diagram 1a). One of the rarest is a brow. This case study describes a woman with a brow presentation following external cephalic version for a breech. The baby was eventually delivered using a rotational ventouse. The discussion includes relevant points concerning these two situations. The case study includes intermittent lay summaries for the non-professional wishing to read and understand the article.

Diagram 1a & b: A breech and cephalic presentation

Case Summary

This is a case of a 31 year old married, Caucasian lady of high socio-economic and intellectual status who presented for booking in her first pregnancy at 8 weeks of gestation. All provisional blood tests were normal and her booking ultrasound scan confirmed her gestation. She had no significant past medical, gynaecological or obstetric history and she opted for midwifery care in an out-reach clinic. Other than a breech presentation which was noted from 32 weeks of gestation she had an uneventful antenatal course.

At 37 weeks she was referred to the hospital for external cephalic version. On this occasion the breech was engaged. An ultrasound scan performed prior to the version showed the baby to be a flexed breech of otherwise normal attitude. The estimated fetal weight was three kilograms; the placenta was posterior; the liquor volume was objectively normal; and the position was right saccro-anterior. The version was performed without tocolysis. The breech was manually disengaged and once the subsequent Braxton-Hicks contraction had gone the version occurred with ease and without undue pressure or distress using the forward roll method.

She presented in labour 8 days after version. At the time of presentation the midwife confirmed a cephalic presentation which was one fifth palpable abdominally. The cervical dilatation was 5 cm and the presenting part was just above the ischial spines. Her membranes were left intact and she was reassessed four hours later. On this occasion she was fully dilated and the membranes were ruptured. The attending midwife felt that the presenting part was 2 cm below the ischial spines but noted there was a significant amount of caput. The midwife thought that the presentation was a vertex and that the position was occipito-anterior. As the patient had no analgesia and an uncontrollable urge to push the active phase of labour was commenced. Once delivery had not occurred within an hour the midwife sought advice from the author.

When the author assessed the patient he noticed caput at 2 cm below the ischial spines with the presenting part 1 cm below the spines. An anterior fontanelle was felt just above the sacrum with minimal moulding inconsistent with the amount of caput. Anteriorly the author felt the orbital ridges, orbits and root of the nose. The diagnosis of a brow was explained to the patient and as the cardiotocogram was normal it was decided to site an epidural and urinary catheter. Once the epidural and catheter were sited the patient was reassessed and the findings were unchanged from before. Furthermore, the ischial spines were not prominent and the pelvis felt capacious in relation to the fetal head. A lengthy discussion was held with the woman and her partner who were also allowed time on their own to talk privately with each other. Two and half hours after the diagnosis of full dilatation it was decided to attempt a rotational vaginal delivery in theatre. It was agreed that if flexion, rotation and descent did not occur with the first contraction following application of the ventouse cup, then a Caesarean section would be performed. She was consented for and fully prepared for a Caesarean section.

In theatre the vaginal examination findings were unchanged. A 4 cm metal Bird cup was applied over the vertex as near to the posterior fontanelle as physically possible and 80 kg / cm2 suction was applied. Flexion and traction was applied which also achieved spontaneous rotation and subsequent delivery with an intact perineum. A health baby boy was delivered and an uncomplicated third stage was achieved using an intramuscular injection of syntometrine and a prophylactic infusion of syntocinon.

The baby boy weighed 3.2 kg and had Apgar scores of 8 at one minute and 10 at 5 minutes. The patient remained in hospital for 8 hours after delivery and the infant was discharged with the mother.

CASE - Lay summary

  1. This is a case of a healthy pregnant woman with no complications when first presenting to the doctor.
  2. A breech was turned by the doctor at 37 weeks (photos 1a-c; & 2a & b).
  3. The woman went into spontaneous labour at 38 weeks and initially progressed normally.
  4. A forehead presentation was diagnosed once she failed to deliver the baby after an hour of pushing.
  5. Delivery occurred using a suction device (ventouse) (photos 3b & c) and repositioning the baby so that it was possible to pass through the pelvis.

Breech

A breech presentation (diagram 1a) occurs in about 2% of term deliveries 1, 2 & 3. A full description of the types, incidence, aetiology, management and complications is beyond the scope of this case study. However, most obstetricians are familiar with breech pregnancies and most good obstetric and midwifery textbooks cover this subject 1, 2 & 3.

BREECH - Lay summary

  1. A breech is when the baby presents bottom first rather than head first (diagram 1a, photo 1a).
  2. It occurs in about 2% of pregnancies after 37 weeks. However it is normal for a baby to be in the breech position prior to labour or 37 weeks with 14% of pregnancies being breech at 29 - 32 weeks 4.
  3. It can be associated with premature labour; fetal abnormalities; abnormally large or small babies; increased or decreased amount of fluid around the baby; abnormalities of the uterus; twins; and abnormalities of the pelvic bones.
  4. After 37 weeks it is sometimes possible for a doctor to turn the baby to the head down position using a technique called External Cephalic Version (ECV) (photos 1 & 2).
  5. If the presentation persists it is safe for many women to attempt a breech delivery depending on the size of the baby; the size of the pelvis; and a mothers previous medical and pregnancy history. Other women require a Caesarean section.

External Cephalic Version

JL McArthur wrote in 1964 5, ‘there are those who enthusiastically recommend it and those who violently oppose it, and still others who express a rather elegant distaste for it’. However, in 1988 there is unchallengeable evidence that external cephalic version (ECV) performed after 37 weeks of gestation for breech is of value 6 - 12. It has been shown to decrease the proportion of non-cephalic births at term and decrease the proportion of women having Caesarean sections 6 - 12. There is no proven value for the role of ECV prior to 37 weeks gestation 13 - 16.

Photos 1a - c: Breech presentation, external cephalic version, and cephalic presentation.

(Click on images to view larger version)

The success rate for ECV vary between 15% and 80% 6. The success rate varies depending on a woman’s parity, type of breech, placental position, fetal size and maternal habitus 17. The reversion rate is 8% for primips and 13% for multips (personal audit). Repeat ECV is possible if reversion occurs. It is possible to rupture the fetal membranes following successful ECV to induce labour and thus prevent reversion.

The complications of ECV are well documented but rarely encountered 1 - 3. They included placental abruption, cord entanglement, rhesus isoimmunisation, uterine trauma, and severe maternal discomfort 1 - 3. To date, no study has demonstrated an overall adverse fetal outcome as a result of ECV and the trend from the meta-analysis is towards a better fetal outcome 6. Many obstetricians consider the potential gains to outweigh the possible complications which is why this procedure is gaining favour again. It was for this reason why ECV was offered in this case.

Many of the supposed contraindications for ECV are disputed or are only relative. The reported contraindications include an alternative indication for a Caesarean section, uterine anomaly, uterine scars, severe maternal hypertension, other severe maternal disease, fetal anomaly, multiple pregnancy, growth retardation, macrosomia, oligohydramnios, polyhydramnios, ruptured membranes, placenta or vasa praevia, previous unexplained antepartum haemorrhage, and previous abruption 1.

Photos 2a & b: External cephalic version in progress (with the permission of Dr Greg Davis MB BS MD FRACOG MRCOG)

(Click on images to view larger version)

Many obstetricians use tocolytic agents such as beta-mimetics to assist ECV. Early published randomised controlled studies failed to demonstrate a benefit 18 - 21. The numbers in those studies are small and many obstetricians still advocate their use. More recently, one study demonstrated that the use of tocolytic agents resulted in successful versions in 30% of women in whom ECV had previously not worked. Furthermore two recent randomised controlled trials have shown a benefit 22 - 23. In this case tocolytic agents were not used and successful version occurred. It is the authors belief that the potential dangers associated with tocolytic agents are such that an attempt should first be made without their use. Only after ECV has failed does the author use tocolysis.

External Cephalic Version (ECV)- Lay summary

  1. 1 ECV is a technique where-by a doctor turns a breech to the head down position (photos 1 & 2).
  2. It is generally considered a safe procedure but is contra-indicated in some women.
  3. The procedure involves the baby being turned manually by pressure on a pregnant woman's tummy (photos 1 & 2).
  4. There is evidence that ECV decreases a woman's risk of a Caesarean section or breech when there is a breech presentation after 37 weeks. However, the success rate is not 100% and a proportion of babies turn back once ECV has been performed.
  5. Some doctors use a drug to relax the uterus when performing ECV. Other doctors do not.

Brow

Incidence

A brow (diagram 2) is the most uncommon form of fetal pole malpresentation 24 - 26. Berger et al 24 found the incidence to be one in 1050 deliveries. In a series of nearly 60,000 pregnancies at the Parkland Hospital between 1991 & 1994 the incidence was 1 in 3240 25. Another author reports the incidence to be 1 in 1500 pregnancies 26.

Diagram 2: An orbito-posterior brow.

Aetiology

The causes are the same as for other malpresentations such as fetal macrosomia, hydrops, and fetal anomaly 1-3. However, no aetiological cause is found in the majority of cases 27. The incidence is twice as common in premature labours 24 & 25. In 1950 Hellman et al 28 reported that 40% were associated with a contracted pelvis. However, Meltzer et al 29 found this association in only 10.9% of cases in 1967. Contracted pelvis is less commonly reported than before in the Western world and it is probable that this association is lower in 1998.

In this example, the woman had another malpresentation prior to external cephalic version. However, no other predisposing factor was ascertained.

Mechanical considerations

A normal presentation is a fully flexed vertex. This accounts for 95% of all cephalic presentations. In this position the suboccipito-bregmatic portion of the fetal head (diameter 9.5 cm) presents through the pelvis. The mid-pelvis is circular with anterio-posterior and lateral diameters equal (12 x 12 cm). With a brow, the mento-vertical portion of the head presents with a diameter classically reported as being 13.5 cm (diagrams 3a & b). It is therefore uncommon for the head to engage or negotiate the mid-pelvis but this may be possible with a small fetus and a capacious birth canal.

Diagrams 3a & b: The fetal head and dimensions.

A - Flexed vertex 9.5 cm. Suboccipito-bregmatic.

B - Deflexed vertex 11.5 cm. Occipitofrontal.

C - Brow - 13.5 cm. Mentovertical.

D - Face - 9.5 cm. Submentobregmatic.

Seventy seven percent of brow presentations are orbito-anterior 30. In these cases the presentation may convert to a mento-anterior face (submento-bregmatic - 9.5 cm diameter) and deliver vaginally. When a brow is orbito-posterior, conversion to a mento-posterior face presentation would not permit vaginal delivery unless rotation occurred. This is because the final extension phase of labour would not be possible in a head which was already fully deflexed.

Brow presentations in labour are normally associated with a prolonged labour and CTG abnormalities. In this case the head was engaged at the onset of labour, the position was orbito-anterior, progression was not delayed and there were no CTG abnormalities.

Diagnosis

Although diagnosis can be obtained antenatally by x-ray and ultrasound, the presentation is normally defined during labour 31. However, it is often missed on vaginal examination as in this case 31. Brows are normally associated with marked caput over the forehead resulting in difficulty in feeling the sutures. Furthermore, if the brow is orbito-anterior, an anterior fontanelle can often be felt facing the sacrum giving an accoucher the false impression that the fetus has a fully flexed vertex presentation with an occipito-anterior position. In such circumstances, the presentation can be defined by palpating anteriorly towards the symphasis pubis where the presence of the root of the nose and orbital ridges confirm the diagnosis.

Management

If diagnosed prior to rupture of the membranes a conversion manoeuvre can be attempted 31. The Thorn manoeuvre 31 consists of manual correction to a mento-anterior face presentation through the cervix under general anaesthietic. However, there are few incidences where this would be considered safe. Furthermore, it is unlikely that many modern day obstetricians have had exposure to this type of management. The author has no experience of the Thorn manoeuvre.

In the presence of a normally progressing labour and no evidence of pelvic contraction, observation is all that is required 27 & 31. Conversion to a face occurs in 28% of cases and rotation of the head can occur if the position is mento-posterior. However, assessment of progress must be made with caution as increasing caput succedaneum can give a false impression of descent. Few obstetricians would consider augmenting labour with oxytocics once secondary arrest or a primary dysfunctional labour was diagnosed because of the potential risks of uterine rupture. However, others recommend the use of oxytocics for on hour 27.

If a brow persists at full dilatation, an assisted vaginal delivery can be attempted 27, 31 & 32. Rotation using Kjelland’s forceps (photo 3a) or ‘posterior’ ventouse cup (photo 3b & c) can increase flexion facilitating delivery 31 & 32. However, an obstetrician should only proceed with extreme caution. With improved outcomes for fetuses and mothers after Caesarean section there is a general trend away from attempting difficult vaginal deliveries 27 & 33. Due to the potential risks of maternal and fetal trauma associated with these procedures it is the authors view that such manoeuvres should only be undertaken in a controlled environment by an experienced obstetrician.

In this case, it was decided to have one gentle attempt at rotation and flexion using the ventouse in theatre. An epidural was sited prior to the attempt and the theatre was prepared for an immediate Caesarean section should it fail. This was a balanced decision made on the basis that prior to the second stage there was no delay; that the pelvis felt capacious; and the baby was not overly large on clinical palpation. Furthermore, a full and informed discussion was had with the mother who was in favour of the attempt. A prior decision was made to abandon the procedure if descent, flexion and rotation were not all achieved with the first contraction after applying the ventouse cup.

In this example a 4 cm Bird cup was applied parallel with the posterior vaginal wall over the vertex as near to the posterior fontanelle as physically possible (photo 3c). The process of traction and head flexion resulted in spontaneous rotation to an occipito-anterior position and facilitated delivery.

Brow- Lay summary

  1. A brow is when a baby presents by it's forehead instead of the back of the head (diagram 2).
  2. It occurs very rarely (between 1 in 1000 and 1 in 3000 pregnancies).
  3. It can be associated with premature labour; fetal abnormalities; abnormally large or small babies; increased or decreased amount of fluid around the baby; abnormalities of the uterus; and abnormalities of the pelvic bones.
  4. When a brow is diagnosed and labour is progressing normally, it is often possible just to observe the labour as the position of the baby may change.
  5. If the presentation persists it is usual to require a Caesarean section. However, in some exceptional circumstances it is possible for the baby's position to be changed by the doctor using forceps or the ventouse (suction device).

Photo 3a-c: Kjellands forceps, a ‘posterior’ ventouse cup (in this example a 6 cm O’Neill cup) and a demonstration of the position required for a ventouse cup for delivery of an orbito-anterior brow.

Conclusions

There are two morals to this story. The first is to remember that even though the cause of a malpresentation may be idiopathic, what ever predisposes to one malpresentation may predispose to another. Secondly, the thought of performing a difficult rotational delivery in a modern day teaching hospital may fill many obstetricians with horror. However, residents and other trainees should remember that a specialist is not a person who can remember rules and dogma but someone who can argue and understand the relative merits and disadvantages of the treatments they recommend. Furthermore, a specialist should be able to modify care pathways that text books write in stone to suit an individual patient and unique clinical scenario.

In this example the author performed a rotational mid-cavity delivery for an orbito-anterior brow presentation when many would have performed a Caesarean section. Some may argue that the appropriateness of this procedure was only apparent in hindsight and that the actions were foolish. ‘Something that may have been acceptable five or ten years ago is not acceptable now’. The author would argue that in this unique situation with this individual patient the procedure was justified irrespective of hindsight. However, once a decision has been made to break the rules a conscious effort must be made to avoid a cavalier approach. The accoucher must bear in mind the potential problems and take the greatest care to avoid them. Furthermore, full informed consent is necessary in order to work with the patient as part of the team.

Related Links

References

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