ACDM ~ Professional
Article of Interest To Midwives
Shoulder Dystocia --
The anatomical principles explaining why the use of a maternal "Hands and Knees" position helps to resolve a Shoulder Dystocia The following comments are excerpts from an ongoing dialogue between obstetricians on the efficacy of this simple, non-surgical technique recommended by midwives to resolve shoulder dystocia.
Synopsis: The original debate on an OB-Gyn ListServ was about the use of episiotomy in an attempt to resolve shoulder dystocia. The controversy was not only the therapeutic value of episiotomy but also whether or not the failure to "cut a big episiotomy" would subject a practitioner to charges of negligence and expose him or her to malpractice litigation.
While there were many dissenting opinions from obstetricians around the English-speaking world, the general agreement among those who posted on this topic was that shoulder dystocia was a bony dystocia (as opposed to a soft tissue dystocia) and therefore episiotomy (and particularly procto-episiotomy) were not indicated unless the practitioner needed the extra room to get a hand into the vagina to maneuver the baby. (see archives of OBGYN-L for full details of the episiotomy debate)
During this debate other possible maneuvers were suggested including the use of a hands and knees position in which an unanesthetized mother can be instructed to physically turn herself over on her hand and knees. The reason that this material position is effective is explained below. The recommendation of the author was: that the first and best maneuver in any suspected SD is to get the mother squatting or kneeling. Obviously, the use of epidural or general anesthesia would preclude the use of this valuable maneuver. An additional risk involved in the use of anesthesia for childbirth is the loss of the ability to use this simple technique.
Also midwives have observed that simply having the mother move herself and particularly, having her turn over seems to help free the impacted should via the torquing of the pelvis which is unstable (therefore flexible) at the end of pregnancy. The hand and knees position also facilitates an additional maneuver in which the practitioner goes into the vagina and draws out the baby's posterior arm. Once the posterior arm is free, it is fairly easy to complete the birth without further problems.
From: Jason Gardosi email@example.com
Subject: Re: episiotomy and shoulder dystocia
Original Question #1:
What I don't quite get the grasp of is your "on hands and knees" position for the patient with shoulder dystocia. As much as I try, and I have tried (and even discussed it with my partners), I can't envision that position giving more room for a shoulder dystocia since every response to the list has stated that it is a bony dystocia, not a soft tissue problem. I'm having trouble understanding the mechanics behind a change in the mother's position and a change in the orientation/size of the bony pelvis which is restricting the delivery of the infant's shoulders.
The anterio-posterior diameter is reduced in recumbent and lithotomy positions where the weight is taken on the sacrum. The sacrum is capable of rotational movement through an axis at the upper part of the sacro-iliac joint, about 5 cm below the sacral promontory (Weisl H: Acta Anat 1955;23:80-91). This movement results in an increase in the AP diameter of between 10 and 20 mm (Borrell V and Fernstrom I, Acta Obstet Gynec Scand 1957;36:42-57 and Acta Radiol 1957;47:365-70). As the sacrum is wedge-shaped in cross section, backwards movement will splay the iliac bones so that the transverse diameter also increases, as shown by JGB Russel's XRay studies (J obstet Gynaecol Br Cmwlth 1969;76:817-20; Br J Obstet Gynecol 982;89:712-5). In a vaginal ultrasound study published as part of my thesis, I have also found that upright positions increase the bispinous diameter (average 4mm). I think the first and best maneuver in any suspected SD is to get the mother squatting or kneeling. Many good midwives already do this, before (and usually instead of) hitting the panic button.
Jason Gardosi MD FRCS MRCOG
PRAM (Perinatal Research, Audit & Monitoring)
Queen's Medical Centre, Nottingham NG7 2UH, U.K.
Tel +44 115 9709211 Fax +44 115 9709791
Subject: Re: episiotomy and shoulder dystocia
Question #2 :
<< I'm having trouble understanding the mechanics behind a change in the mother's position and a change in the orientation/size of the bony pelvis which is restricting the delivery of the infant's shoulders. (snip)
Thanks for any light you can shed on my biomechanical dilemma.
Response From: Arthurfree@aol.com:
Biomechanically, there are a couple of things that may well help with the move to hands and knees. The first is the simple act of turning over - assymetrical loading of the pelvis while turning may actually dislodge the impaction. The second and probably more important is that gravity and "arching" the back may help dislodge the *posterior* shoulder by decreasing the sacral promontory. Folks who have tried this maneuver pass on that it tends to be easier to go in and get the posterior arm in this position as well. Midwives I've spoken with on the subject have been confident enough in the maneuver that they tend to move to hands and knees immediately if MacRoberts doesn't work rapidly.
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