Re: Risk of 2nd trimester amniocentesis
From: The-Hung Bui (The-Hung.Bui@ks.se)
Mon May 21 08:43:04 2001
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From: evsono@pipeline.com (art fougner, md)
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Subject: Re: Risk of 2nd trimester amniocentesis
we use a disposable needle-guide which allows for insertion at a fixed
angle and see the entire length of the needle. transducer is draped
with sterile sheath - Civco - which we call the world's largest condom.
For latex sentive folk, we'll use sterile non-latex glove. we use the
Cook Needle with echo-tip at 22 gauge. most women don't feel more than
what they feel during a venipuncture. we quote loss rates comparable to
the literature - altho the "phone-call sign" suggests loss rates may be
lower.
art
At Sun, 20 May 2001, James S. Smeltzer, MD wrote:
>
>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
>>
--
art fougner, md
A series of 1000 cases begins with but a single anecdote.
