USING MVA AND EVA EQUIPMENT
||Prepare the aspirator
- Begin with valve buttons open and
plunger pushed fully into the barrel.
- Close valve by pushing the buttons
down and forward until locked in place.
||Create the vacuum
- Pull the plunger back until its arms
snap outward over the rim at end of the barrel.
- Make sure the plunger arms are positioned
over wide edges of the barrel rim.
||Gently dilate the cervix
- Use dilators of increasing size to accommodate
cannula size chosen based on gestational weeks.
- Denniston – dilate to cannula size
(e.g. size 7 for 7 mm cannula)
- Pratt – dilate to cannula size x 3
(e.g. 21 French for 7mm cannula)
||Choose a cannula
- Flexible: longer with two openings at tip
- Rigid: larger single opening at tip
- No significant difference in safety or efficacy
- Larger: faster aspiration, intact tissue
- Smaller: less dilation and resistance
NAF Provider’s survey (O’Connell 2009):
- 54% used size (in mm) = weeks gestation
- 37% used 1-2 mm < weeks gestation
- 9% used 1-3 mm > weeks gestation
||Insert the cannula
- Apply traction to tenaculum to straighten uterus.
Then holding cannula with fingertips, gently
insert through cervix with rotating motion.
- Attach aspirator to cannula.
- Do not grasp aspirator by plunger arms.
||Release the valve buttons
- When the pinch valve is released, the vacuum is
transferred through the cannula into the uterus.
- Blood, tissue, and bubbles will flow through the
cannula into the aspirator
||Evacuate the uterus
- Rotate the cannula and move it gently from fundus
to the internal os, applying a back and forth motion as clinically indicated until:
- Grittiness is felt through cannula
- Uterus contracts and grips cannula
- There is increased cramping, and / or
- No more blood passes through cannula
||Choice of Vacuum for Aspiration
- Availability / preference determine use
- MVA is FDA approved to 12 weeks
- Some use > 1 MVA to facilitate emptying, or switch to EVA > 9 weeks
- Minimal differences in pain, anxiety, bleeding, or acceptability (Dean 2003)
- EVA sound disturbs some patients; silent, in-wall suction is available.
- Attach cannula and close thumb valve
- Place cannula into uterus
- Turn on and check suction gauge
- To modify: turn dial or adjust valve
- Release suction (open thumb valve) when passing through cervical canal.
||Inspect the tissue
- Rinse and strain the tissue
- Place tissue in a clear container
- Backlight is recommended to inspect
tissue if gross visual inspection is non-diagnostic.
||Gestational sac at 6 weeks
- Shredded (on left) vs. intact
- To minimize shredding, consider using MVA
(< pressure than EVA); slightly larger cannula.
||Membranes and Villi (POC)
- Frond-like villi
- Clumps held by membrane
- Transparent like plastic wrap
- Luminescent; light refractory
- Turns white if vinegar added
- More stretchy
- Floats more in liquid media
- Size: see coin sizes above
|Decidua (not POC)
- No fronds
- No villi or thin membrane
- Opaque like wax paper
- Less light refractory
- Minimal color change
- More breakable
- Sinks more in liquid media
- Quantity variable
Caution not to confuse
a) gestational sac (8 week) with
b) decidua capsularis, a portion of the decidua
which grows proportionally to gestational sac
but is thicker and tougher(Image: Edwards, J).
|Fetal part development
Parts may be seen earlier.
≥ 10W look for 4 extremities, spine,
calvarium and gestational sac.≥12W must find all
fetal parts + placenta
Illustrated images adapted from MVA, a presentation by Physicians and ARHP, 2000; 2012.