Re: Risk of 2nd trimester amniocentesis
From: Terry J DuBose (tjdubose@juno.com)
Sun May 20 16:53:59 2001
This is very similar to the method we use. We do us a zip-lock plastic
bag that is gas sterilized in the tray as the transducer sheath. I scan
while the obstetrician and I discuss the best pocket to go for.
We then do the prep. The sonographer-assistant (me) gloves right hand
and uses left to squirt gel in the bag and gently lower the transducer
into the bag which is held by the physician. I keep the transducer cable
out of the field with my left hand and scan with the gloved right. When
we agree again on the area, I hold the transducer in the location while
she gets the needle and approaches the stick at the edge and in the of
the plane of view. I move the transducer only enough to visualize the
needle, we can see the tissue around the needle move. I keep the needle
tip visualized because it usually emits a bright echo.
This allows her to have both hands free to deal with the needle,
syringes, and tubes.
Peace, Terry J DuBose
Little Rock, Arkansas USA
On Sun, 20 May 2001 16:29:44 -0500 "James S. Smeltzer, MD"
<gaperina@mindspring.com> writes:
> Allen,
>
> The scan-head of a curvilinear scanner defines a plane. The needle
> is within
> that plane until fluid is encountered.
>
> The method:
>
> Background:
>
> 1. Physical fact: Realize that vertical and horizontal are the ONLY
> directions we can reproduce with fair exactitude. If we are more
> than a few
> degrees off on vertical we fall over. We don not fall over, because
> we KNOW
> vertical and can reproduce it either with the plane of the scan
> head,
> amniocentesis needle or both.
>
> 2. Physical fact: If a plane is vertical and one point of a
> vertical line
> is in that plane, then ALL points of that line are on that plane.
>
> The principal:
>
> Identify the entry point for a vertical insertion into the pocket
> with the
> vertical scan head. Angling the plane 45 degrees and holding it in a
> vertical plane that includes the insertion point and inserting the
> needle
> vertically permits one to see the needle. If you insert to where you
> should
> see the needle traveling from the top right at 45 degrees and don't
> angle
> the probe a few degrees until you do. If you still do not something
> is off
> so "flash" the stylette with color on - beware as there is some beam
> width
> and you can see the needle when not in the exact plane, the max echo
> is the
> right plane within the 1-3 mm range you have when doing a PUBS.
>
> The Method:
>
> Do NOT use Monoject needles. Use only Becton Dickenson standard
> spinal
> needles, 20 or 22 Ga as per preference. 3.5 inch for most women, 5
> inch for
> large - 20 really helps visibility here. Draw is much quicker with
> 20, but
> if you hit a vessel, you are more likely to lacerate it. 22s are
> better for
> Early amnios, as they are sharper and less likely to tent the
> amnion, and
> the patient barely feels it if you are swift.
>
> Use the sonogram to identify the best likely sites - whether the
> baby moves
> or not. 5-7 MHz works best, slightly excessive gain to show lurking
> loops of
> cord and more easily see the needle and see any streaming if present
> after
> tap.
>
> Prep the abdomen with iodophore to include these sites.
>
> Check your syringes and extension tube (short 10- 30 cm). Expel air
> to break
> seal in syringe. attach to extension tube.
>
> Glove the transducer and remove air.
>
> Scan the sites to refind the best one, with the transducer oriented
> anatomically so the plane you see on the screen corresponds to the
> plane you
> have in front of you so what you see is what you get (For a righty
> working
> from the patient's left side this will be BACKWARDS anatomically for
> the
> sonographer on the patient's right).
>
> Find the best insertion point for a vertical insertion and mark it,
> avoiding
> fetal head, placenta, cord and fetus in that order of importance.
> Note the
> depth of the uterus from the skin.
>
> Mark it with a needle cover or finger nail.
>
> Back off so the spot is at the end of the gloved probe.
>
> Insert the needle vertically at the spot to a depth of about a cm
> less than
> the pocket vertically and rapidly. The patient will probably feel
> this as
> the parietal peritoneum is at about that location. Have the patient
> continue to breath slowly, see your shot and take it. Adjust as
> needed to do
> this.
>
> Needle shows more readily if gain is up a bit. Stylette moving in &
> out are
> usually visible (esp with bevel marked by notch in stylette hub
> towards
> probe). They are ALWAYS visible - a little too visible, even
> slightly out of
> plane with the color on.
>
> When needle in, assistant holds probe while you remove stylette,
> attach
> extension tube, and draw sample.
>
> If flow stops, release suction on syringe, turn needle with
> extension tube -
> you do not need to touch it.
>
> If flow does not come, have assistant find needle, reinsert stylette
> and
> slide up & down. If it looks like you are in but no flow, you did
> not
> cleanly enter the pocket. If you have room, stylette in and advance
> a cm or
> two quickly. If desperate and you have room you can enter the deep
> membranes, backed up by decidua and myometrium to push the amnion
> onto the
> needle.
>
> For PUBS, I have the operator continue to hold everything and have
> the
> assistant remove the stylette, insert the tuberculin syringes for
> samples
> (stat ABG and Hemocue and CBC or other specimen), push the
> vecuronium, and
> then insert the extension tube for IUT, start the transfusion - if
> streaming
> of initial saline is seen in the cord.
>> ----- Original Message -----
> From: "Allen Worrall" <jworrall@alaska.net>
> To: "Multiple recipients of list ULTRASOUND"
> <ultrasound@mail.medispecialty.com>
> Sent: Sunday, May 20, 2001 1:05 PM
> Subject: Re: Risk of 2nd trimester amniocentesis
>
> > Jim, thanks for your response. Please describe the two-handed
> technique of
> > amniocentesis. Do you place the transducer in a sterile glove? Do
> you hold
> > the transducer with one hand and the needle with the other?
> >
> > Allen
> >
>
