Category Archives: Emergencies

Arms: Identifying the need to intervene

This blog will discuss how to recognise the need to intervene to deliver the arms in a vaginal breech birth which has been physiological up until that point. Descriptions are provided as if the woman is in an upright kneeling position, facing away from the attendant midwife or obstetrician. I have been somewhat prescriptive about how delay and dystocia can be evaluated. Experienced practitioners will have their own comfort levels. My intention is to stimulate discussion among modestly experienced practitioners, to help distinguish patterns calling for intervention from those which do not. Once the umbilicus is born, depending on the condition of the baby, unnecessary delay in identifying dystocia could be dangerous.

Recognising what is normal …

birth of the extended fetal legs

birth of the extended fetal legs

Midwives and obstetricians attending vaginal breech births need to learn to ‘read’ what is visible (eg. outside the vagina), as it provides clues about what might be happening at higher levels in the pelvis. In the normal breech mechanisms, the breech descends sacrum transverse, with the fetal back to one side or the other. A rotation occurs as the shoulders engage in the pelvis in the transverse diameter, just as they do in a cephalic birth. The fetal torso fully rotates, finishing fully facing the attendant — “tum to bum.” When this rotation is observed externally, it provides reassurance that the birth is progressing internally. Once the umbilicus is born, there will be a short pause (usually less than 30 seconds) before gravity will begin to pull the unimpeded fetal body down further in the pelvis.

birth of the umbilicus - fetal torso fully rotated, "tum to bum"

birth of the umbilicus – fetal torso fully rotated, “tum to bum”

When the shoulders reach the pelvic floor, restitution will occur, just as it does in a cephalic birth. Simultaneously, internally, the aftercoming head is rotating to enter the pelvis in the transverse/oblique diameter, just as it does in a cephalic birth. Externally, this is observed as a slight rotation, in which the anterior fetal arm is released under the pubic arch. Almost immediately (usually less than 30 seconds), another rotation occurs in the opposite direction, and the posterior arm is released under the perineum. This coincides with the final internal rotation of the head, as it realigns to an occipito-anterior position ready to be born, just as it does in a cephalic birth.

A thorough understanding of what is ‘normal’ in a vaginal breech births helps attendants to be aware of when deviations from expected patterns may indicate a threat to fetal well-being. The video below repeats the above information, so that you can recreate it with a doll and pelvis in order to thoroughly understand why this mechanism unfolds in the way that it does.

… and what is not normal.

the anterior arm is caught up on the symphysis pubis - rotation is incomplete

the anterior arm is caught up on the symphysis pubis

A deviation from the mechanism described above may indicate a problem, if it is accompanied by a delay. In some cases, when women give birth in upright positions, the combination of a roomy pelvis and the effects of gravity creates a situation in which the fetus can tumble through almost all at once, and the mechanism remains unobserved or seemingly irrelevant to this baby and this mother. If the birth is proceeding rapidly, and the baby is in good condition, there is no need to intervene unless progress stops. Just prepare to break the baby’s fall.

The signal to intervene is an observed variation in the mechanisms, accompanied by a delay (> 30 seconds), unresponsive to spontaneous maternal movement — or any occasion in which the fetus appears compromised. In other words, you observe that descent has stopped and encourage the mother to wiggle, lift a leg, shift her torso, or some other gentle method of shifting the limb which is stuck – but it remains stuck. Some variations suggesting intervention may be necessary include:

Incomplete rotation

prayer hands

prayer hands

The baby has been born to the umbilicus. However, the torso has not completely rotated to face the attendant; the shoulders appear to be in the oblique or A-P diameter of the pelvis. You may need to restore the mechanism. Remember: the shoulders engage in the pelvic inlet in the transverse diameter, visible externally as a complete rotation to face the attendant. If the rotation is not complete, and progress does not resume with spontaneous maternal movement, assume one or both arms are caught up on the pelvic inlet. You can encourage rotation with your hands on the bony prominences of the pelvis (much like Løvset’s), but if this is not easily effective, do not risk twisting the fetal spine. Instead, use ‘prayer hands,’ with your fingertips against the bony prominences of the shoulder girdle, palms flat to avoid fetal organ damage. Elevate slightly to disimpact, and rotate the fetal torso so that the shoulders are in the transverse diameter. Descent should resume following this rotation. Once you have started to intervene, continue to assist the head to be born by manually flexing the head and controlling the delivery, or using shoulder press.

I have heard several midwives use the term ‘prayer hands,’ including Helen Dresner-Barnes and Gail Tully.

Posterior arm born first

This is not always a problem, but it often happens because the anterior arm is nuchal, eg. raised beside the head. Again, not always a problem. Sometimes an arm in front of the face helps to keep the head flexed, and they can be born simultaneously. If descent and rotation continues, and the baby appears to be in good condition, watch and wait. However, if the posterior arm (closest to the attendant) is born first and there is a delay (> 30 seconds) before the birth of the anterior arm (nearest the symphysis pubis), intervention is likely required. Suspect a nuchal arm, raised alongside the head. Insert your hand behind the fetal back on the side of the arm which needs to be released. Sweep down, in front of the fetal face, and out. This will restore the mechanism and enable the head to descend to the pelvic outlet. If the arm is positioned behind the head and cannot be swept down, rotational manoeuvres may be required, using prayer hands.

One arm born with shoulders in the anterior-posterior (A-P) diameter

fingertips help to maintain alignment of the fetal head during the rotational manoeuvre

fingertips help to maintain alignment of the fetal head during the rotational manoeuvre

Sometimes, the posterior arm is born and the fetus has not rotated at all; the shoulders appear to be in the A-P diameter, with the posterior shoulder visible under the perineum. This is because the anterior arm is nuchal, stretched alongside the fetal head, and prohibiting further descent. It has become wedged tightly against the symphysis pubis, and it is not possible to sweep down in front of the fetal face. This situation will not respond to subtle maternal movements and requires immediate and assertive intervention, in the form of elevation and rotation. In my own experience of using rotational manoeuvres in this situation, I have used ‘prayer hands’ to rotate the fetus into an occipito-posterior position, where it becomes possible to sweep the nuchal arm down in front of the face and out under the pubic arch. The head should be kept in alignment and rotated back to an occipito-anterior position, where shoulder press or manual flexion can be used to deliver the head without delay.

A pause after the birth of the anterior arm, lasting >30 seconds

if a delay occurs, the second arm may need to be swept down in front of the fetal face

if a delay occurs, the second arm may need to be swept down in front of the fetal face

After the birth of the anterior arm, most of the baby is out. Gravity will usually do its magic, continuing to bring about steady but gradual descent. As the head is rotating into A-P alignment internally, ready to be born, the second arm will release under the perineum. If this process does not resume soon (< 30 seconds) after the birth of the anterior arm, and progress promptly, it suggests two possible problems. Either the posterior arm is blocking the head from descending and rotating, in which case sweeping the second arm down in front of the fetal face should result in both the delivery of the arm and alignment of the head. Or the head has not completely descended into the pelvis. In which case, delivery of the second arm will enable you to get on with assisting the head to be born.

Mechanisms appear normal, complete rotation, umbilicus born, with no further descent for >30 seconds, and especially after the onset of the next contraction

This is when apparent problems with the arms are not actually problems with the arms. The arms are under the sacrum, ready to be born, but they have not been born yet because the head has not entered the pelvis. Although it is possible to sweep them down, this will not solve the underlying problem that the head is extended at the inlet and impacted in the A-P diameter. As described above, the head needs to rotate into the oblique/transverse diameter to enter the pelvis. Begin by lifting the fetal torso to elevate the head off the pelvic inlet slightly. Then rotate to release the arms and enable the head to engage. As you have started to intervene, continue to assist the head to be born, flexing the head manually or using shoulder press once the head has entered the pelvis.

— Shawn

Thank you to Joy Horner, for sharing the photo on which the sketch above is based. And to Mary Cronk, who shared her slides and experience of managing a nuchal arm with me before I encountered it myself, enabling me to resolve it successfully. I am very grateful for the sharing of midwifery knowledge, so I am doing my own sharing in the hope that it will be helpful to another midwife or doctor in a tricky birth.

Read More

Visualizing the obstructed breech: Read Dr Rixa Freeze’s blog on how Spinning Babies midwife Gail Tully explains how to free the obstructed arm.

Videos

In this video, the posterior arm is born first, and the obstetrician (Diego Alarcon) gently assists the anterior arm by sweeping it down across the baby’s face.

In this video, the baby is born with the sacrum to the mother’s left and slightly posterior, it looks like due to the positioning of the feet. When the normal rotation to sacral anterior does not occur, the obstetrician (Michel Odent) immediately recognises that the mechanism has deviated from normal and intervenes. He assists the anterior arm to be born by sweeping it down across the baby’s face, restoring the mechanism.

Shoulder Press and Gluteal Lift

Helping the aftercoming head to flex in upright breech births

When women are in upright positions, many breech births will proceed completely spontaneously because the birth canal follows the flow of gravity. However, the attending clinician may need to assist, either because maternal effort no longer results in steady progress, or because the baby appears compromised and assistance will result in a quicker delivery.  In this blog, I describe one manoeuvre I have learned to help in upright breech births.

The shoulder press is very effective in the following circumstances:

Deflexed head in mid-pelvis

Deflexed head in mid-pelvis

  • The aftercoming head has descended through the pelvic inlet and is either on the perineum (chin visible) or mid-pelvis (chin not visible, but easily reached in the sacral space); and the occiput is anterior
  • The mother is in an upright, forward-leaning position (e.g. hands/knees or kneeling)
  • The clinician facilitating the birth is behind the mother, and the baby is directly facing the clinician (‘tum to bum’ with mother), with head and body in alignment
When baby's head has descended into the pelvis, the pubic bones are directly behind the occiput

When baby’s head has descended into the pelvis, the pubic bones are directly behind the occiput

In this scenario, the maternal pubic arch is directly behind the baby’s occiput. When pressure is applied to the baby’s torso just below the clavicular ridge, guiding the baby’s body straight back through the mother’s legs, the pubic arch will push the occiput up and forward. This causes the aftercoming head to flex and descend, following the curve of the birth canal. The sternocleidomastoid muscles (SCM), responsible for head flexion, attach to the superior aspect of the clavicle and keep the head in alignment throughout this process.

Gluteal Lift – If descents stops with the perineum tight on the baby’s forehead (bregma), and the shoulder press alone has no further effect, an assistant can augment the manoeuvre by lifting the woman’s buttocks up and out. This lifts the perineum over the bregma as the primary attendant performs the shoulder press, moving the baby in the opposite direction. This assisted manoeuvre is especially helpful when the woman has a very full figure, or the perineum is especially tight and intact.

The feeling and effectiveness of this manoeuvre is very easy to replicate using an obstetric model, turned upside down, as in the video below.

Potential benefits

Preserving an intact perineum. An intact perineum helps to maintain beneficial fetal flexion, and routine episiotomy should be avoided for this reason. However, when the aftercoming head has descended onto the perineum, reaching the maxillary or malar bones to perform a modified Mariceau-Smellie-Veit (MSV) can be difficult. Therefore, many clinicians will cut an episiotomy early in order to avoid cutting one while the baby’s face is on the perineum. However, this is not necessary. When the chin is visible, pressure on the maxillary bones through an intact perineum is possible, in combination with upward pressure on the occiput behind the pubic arch, enabling descent to continue. However, the shoulder press is more effective.

The path of the head must follow the arc of the pelvic cavity

The path of the head must follow the arc of the pelvic cavity

Clinicians who are inexperienced or untrained in manoeuvres specific to upright birth will be tempted to pull down on the baby’s torso to deliver the head. However, this does not follow the direction of the birth canal in the same way as the shoulder press as described. Pulling rather than pushing is potentially more likely to result in severe perineal damage, and may also cause cervical nerve damage in the baby due to increased resistance from the intact perineum.

Potential risks

Fractured clavicle. When applying pressure on the clavicle, fracture is an obvious potential risk. This potential risk can be minimised by spreading the fingers to apply even pressure just below the entire ridge, or by applying pressure with fingers or thumbs at the distal aspect, near the glenohumeral joint. The pressure exerted is firm but is not significantly different to that applied when delivering an anterior shoulder in a supine cephalic delivery, and therefore no more likely to result in trauma. The shoulder press minimises the amount of force needed to achieve delivery by promoting maximum head flexion and descent in the direction of the birth canal.

Limitations

The shoulder press as described, on its own, may not resolve a dystocia caused by a deflexed or hyperextended aftercoming head. A very high chin, pointing upwards, identifies a hyperextended head; only the bottom jawbone (resembling a ‘bird beak’) is felt at the very top of the maternal sacrum. If the deflexed head has impacted at the pelvic inlet, the baby’s whole body may need to be lifted in order to flex and/or rotate the head to oblique so that it can enter the pelvis before the shoulder press is useful. Additionally, suprapubic pressure performed by an assistant may help flex the head enough to pass through the pelvic inlet.

Uses

The practice of supporting breech births with the mother in an upright position is somewhat controversial, as minimal research evidence regarding effectiveness exists. Although breech experience is generally at a very low level, most clinicians are only trained to perform lithotomy manoeuvres, and therefore the RCOG recommend lithotomy as the preferred maternal position (RCOG 2006). However, increasingly women are requesting freedom of movement and their own preference to be upright, which is potentially a more satisfying birthing position (Thies-Lagergren L et al 2013). In the absence of evidence that such an approach increases risks, introducing upright manoeuvres into mandatory training will enable this option.

In addition, through discussions with other midwives and participation in the risk management process for various Trusts, I have been informed of several cases of undiagnosed breech births where women were instructed to get onto their backs on their floor following the diagnosis of a breech in labour, due to lack of an obstetric bed in that setting. In some cases, this has been associated with severe delay in delivering the aftercoming head. In true lithotomy, head flexion is promoted by allowing the baby to hang off the end of the bed, where the maternal pubic arch again is responsible for lifting the occiput as gravity gently pulls the baby through the birth canal. This cannot occur on the floor, and the head becomes deflexed. In these cases, the midwives were only trained to perform lithotomy manoeuvres, and instructed that guidelines required them to manage breech births in this way, but the births occurred in settings with no obstetric bed. Providing mandatory training in upright breech to those working in midwifery-led settings will potentially improve outcomes in emergency cases in the short term, and increase maternal choice in the long term.

Read more

Visualizing the obstructed breech: Read Dr Rixa Freeze’s blog, on how Spinning Babies midwife Gail Tully teaches this manoeuvre.

Sources

I first learned about this mechanism from Dr Anke Reitter, FRCOG, of Frankfurt, Germany, and Jane Evans, an experienced UK Independent Midwife. At the University Hospital Frankfurt a similar technique is called ‘Frank’s Nudge’ after the lead obstetrician, Prof Frank Louwen, who introduced the upright management of breech birth to their unit. I do not refer to the manoeuvre as ‘Frank’s Nudge’ because my technique may differ slightly, and that team has yet to publish their own description of their manoeuvre. Some have described the mechanism as a reflex action, but my hands have experienced it as purely mechanical, and much more effective than Mariceau-Smellie-Veit when women are upright. I can only speak for my experience.

Shawn

Need a Reference?

Evans J. (2012) Understanding physiological breech birth. Essentially MIDIRS. 3(2):17–21.

RCOG (2006) The Management of Breech Presentation. RCOG Green-top Guidelines, No. 20b. London, Royal College of Obstetricians and Gynaecologists.

Thies-Lagergren L et al (2013) Who decides the position for birth? A follow-up study of a randomised controlled trial.” Women and Birth 26(4): e99-e104.

Walker, S. (2015) Turning breech upside down: upright breech birth. MIDIRS Midwifery Digest 25(3):325-330. This is the first time shoulder press is mentioned in print & contains a photo series.

“[B]irth attendants can assist the head to flex using forward pressure on the fetal chest — ‘shoulder press .’ This is applied in the sub-clavicular space, using either the fingers along the ridge, or the thumbs at the distal end of the clavicle, with the attendant’s fingers wrapped around the fetal shoulders. When the fetal body is brought straight back through the maternal legs and towards the maternal abdomen, the pubic bone will assist head flexion. However, if the fetal head is extended and caught at the inlet, the attendant may need to lift the fetal body to displace the head to a higher station, and rotate into the oblique or transverse diameter to assist engagement, before the flexion described above can be achieved — ‘elevation and rotation .’ (p 328)

Walker S, Scamell M, Parker P. Standards for maternity care professionals attending planned upright breech births: A Delphi study. Midwifery. 2016 Mar;34:7–14.

(‘Using subclavicular pressure to flex the head’ is an agreed manoeuvre professional should be taught in this consensus research involving an experienced international panel of midwives and obstetricians)

Updated 15 June 2016

Listen to midwives, listen to women

I always smile when people say, “It’s all well and good to support natural breech birth, but what happens if the head gets stuck?” Those of us who are supporting woman-centred, modern breech birth take an equally realistic view about the need to intervene in a skilled and confident manner when help is needed, although we are probably more realistic about the frequency with which such intervention is required. We also obsess about creating trusting relationships and environments which facilitate more spontaneous, easier births, with the end result that we need to use our skills less often.

However we sometimes rely on these skills to achieve a safe outcome. Therefore we share our experiences with others, for when they might be needed. And we know that supporting others to confidently support more breech births will create new knowledge which will in turn help us to improve our own practice.

Where does this knowledge come from? Hint: not Randomised Controlled Trials. One of the many ways midwives create knowledge about practice is by listening to each other and listening to women. For example, in the training aid linked above, one of the options involves assisting a woman who is on all fours to become straight upright on her knees, and applying suprapubic pressure. This is how my own personal learning about that happened (participants not identified to maintain confidentiality):

The baby’s head was hyperextended at the time of delivery, but not before. Woman on all fours, no progress with the next contraction, no spontaneous movements from the baby to assist his own flexion. Neither the midwife managing nor the Registrar who was supporting could reach the baby’s chin, just what felt like a bird beak (the lower jaw bone) pointed up to the sky, so Mariceau-Cronk was not an option. All present were fairly inexperienced, and no training aids were available, so the decision to get the woman upright was instinctive. The decision to apply suprapubic pressure while doing so was based on RCOG guidelines about how to help when the woman is in lithotomy, transcribed to the current situation. The occiput was felt during suprapubic pressure. Then suddenly the baby’s head dropped into the pelvis, and was immediately born wearing his placenta like a hat. Several minutes of resuscitation were required. Baby recovered quickly and well.

Following on from this story, I returned to the sources I use over and over again. Anne Frye’s Holistic Midwifery described how some midwives get the woman upright (for breech and shoulder dystocia) because this tightens the abdominal muscles, promoting head flexion. So someone else has a theory for how it works. There is also increasing radiological evidence that when upright or prone (e.g. shoulders, pelvis and knees in a straight line), the pelvic inlet is largest, while squatting significantly enlarges the mid-pelvis and pelvic outlet. The strategy of assisting the woman to move into an upright posture and use suprapubic pressure may have resulted in an even better outcome if performed earlier, as soon as the dystocia was identified.

Once you begin to see the patterns, they emerge in the stories you immerse yourself in. Reading Jennie Clegg’s story about her ‘Breech VBAC at home,’ I found this:

The next push I gave it everything I had and rumping happened very quickly followed by the body; the relief of the pressure was immense. Two sharp sensations happened which were the legs releasing, I remember looking through my legs and seeing a little body! Then there were a few sharp uncomfortable movements which were caused by the baby wriggling its arms out. My contractions at this point had stopped.

Debs could see no chin on the chest to examined me and found the head to be extended. An ambulance was called and Debs started manoeuvres to birth the baby. No movement was felt so I was encouraged to change position and Michelle tried nipple stimulation to get contractions coming. Michelle and James helped me to stand, Debs attempted head flexion, movement was felt and I was encouraged to push, baby was born immediately followed by the placenta! (Midwifery Matters, ISSUE 135, Winter 2012)

This scenario was slightly different, but maternal movement was again helpful. Jane Evans, a midwife with many years of breech experience, writes and talks about how her understanding of the physiology of breech birth has been informed by listening to and close observation of women (Evans 2012a, Evans 2012b).

Listen to women. Listen to midwives. Share your stories. Share your skills.

Feel free to share your own stories in the comments below. Community support for breech professionals is available via a Breech Birth Network Facebook group.

References

Michel, S. C., Rake, A., Treiber, K., Seifert, B., Chaoui, R., Huch, R., . . . Kubik-Huch, R. A. (2002). MR obstetric pelvimetry: effect of birthing position on pelvic bony dimensions. AJR Am J Roentgenol, 179(4), 1063-1067. doi: 10.2214/ajr.

Anne Frye’s Holistic Midwifery: A Comprehensive Textbook for Midwives in Homebirth Practice, Vol II is now available to download as a PDF, you lucky ducks! My father still complains about having to transport the heavy tome across London on the underground when he brought it to me from America one Christmas.

Cord prolapse: what do midwives do?

This post was originally written as a Letter to the Editor, but when I went to submit it, I discovered the on-line journal does not accept any unsolicited writing. All of the articles are ‘commissioned by the Editors from specialists in their field,’ so I guess we should read them as more of a pronouncement than the opening of a dialogue?

I have some concerns about an intervention for cord prolapse described in a recent article on Abnormal Labour (Obstetrics, Gynaecology and Reproductive Medicine, Volume 23, Issue 4, Pages 121-125, April 2013): “Filling the urinary bladder (with 500-750 ml normal saline) helps to elevate the presenting part off the cord – this technique is particularly more suitable to the homebirth or standalone midwifery unit setting where prolonged manual elevation during transfer to an obstetric unit is difficult to maintain. In the hospital setting, filling the urinary bladder offers no increase in survival or improvement in fetal umbilical cord gases over manual elevation alone, although may be a useful adjunct if there is no theatre immediately available.”

As I said, I have some concerns. The authors suggest filling the urinary bladder as a method of preventing cord compression following cord prolapse. They say this technique has not been shown to improve outcomes in a hospital setting, but is ‘particularly more suitable to the homebirth or standalone midwifery unit.’ There are no references provided for the evidence related to use of this technique in either setting. As a midwife who has worked in two countries and the complete range of midwifery-led settings, I have never encountered this technique, nor anyone carrying appropriate equipment to enact it. I am concerned that an unproven, potentially harmful intervention not in widespread use is being presented as best practice, for use by midwives.

I am also concerned that, although the case scenario ended in a vaginal birth, the discussion presents caesarean section as the preferred method of delivery when a cord prolapse is seen, without discussing the importance of determining whether or not delivery is imminent before intervening. Cord prolapse is a common occurrence preceding the birth of a second twin, and during the births of babies with complete (knees flexed) and footling breech presentations. A prolapsed cord at full dilatation may precede a healthy vaginal birth with a delivery interval significantly less than a caesarean section (Gannard-Pechin et al 2012, Huang et al 2012), and when accompanying non-frank breech and twin births is associated with fetal compromise less often than for cephalic singletons (Kouam & Miller 1980, Broche et al 2005). Therefore, giving the impression that the best course of action upon seeing a cord in every situation is to elevate the presenting part manually, effectively preventing descent and spontaneous delivery in preference of a crash section, in many instances will cause more harm than good. This may seem like a matter of course to experienced practitioners, but it won’t be for the inexperienced.

Judging which instances require such emergency measures, and which would benefit from cautious expectant management, is a matter of skill and experience (in theory and practice), to which articles like the one linked above could usefully contribute. Factors to consider include cervical dilatation, type of presentation, signs of fetal distress, and descent with expulsive effort. Additionally, management of breech deliveries with the woman in an all fours position may reduce cord compression (as the cord is above the fetal body rather than below), and can easily be converted to a knees-chest position for more active intervention if delivery does not progress as quickly as expected. This is a strategy midwives are actually using in the community.

Update (December 2014): Those of you who are interested in this topic should read this report from the Netherlands:

M Smit et al, Umbilical cord prolapse in primary care settings in the Netherlands; a case series, Part 2, The Practising Midwife 17 (7); 34-38.

When considering what is recommended and best practice for midwives working in primary care settings, evidence needs to come from those settings. In this study, 2/8 UCP’s were managed with retrograde bladder filling, and these two instances were associated with the poorest Apgars, and the only death reported. While the numbers are small, they suggest that bladder filling in primary care settings may not offer benefits over manual elevation of the presenting part. Additionally, because it is time consuming, especially for a single midwife on her own at home, it may lead to unnecessary delays, compared to outcomes which were conducted in settings where assistance from other staff was immediately available.

What do you think? Are you carrying equipment to inflate women’s bladders if you detect a cord prolapse at home?

Broche, D. E., Riethmuller, D., Vidal, C., Sautiere, J. L., Schaal, J. P., & Maillet, R. (2005). [Obstetric and perinatal outcomes of a disreputable presentation: the nonfrank breech]. J Gynecol Obstet Biol Reprod (Paris), 34(8), 781-788.

Gannard-Pechin, E., Ramanah, R., Cossa, S., Mulin, B., Maillet, R., & Riethmuller, D. (2012). [Umbilical cord prolapse: a case study over 23 years]. J Gynecol Obstet Biol Reprod (Paris), 41(6), 574-583. doi: 10.1016/j.jgyn.2012.06.001

Huang, J. P., Chen, C. P., Chen, C. P., Wang, K. G., & Wang, K. L. (2012). Term pregnancy with umbilical cord prolapse. Taiwan J Obstet Gynecol, 51(3), 375-380. doi: 10.1016/j.tjog.2012.07.010

Kouam, L., & Miller, E. C. (1980). [Prolapse of umbilical cord – new aspects]. Zentralbl Gynakol, 102(13), 724-733.