Posterior Sagittal Anoplasty / PSARP Incision for Males
Colorectal Center surgeons at Cincinnati Children's Hospital Medical Center provides information about the incision in Posterior Sagittal Anoplasty / PSARP.
The incision starts somewhere in the middle portion of the sacrum and continues down through the center of the external sphincter, ending one to two centimeters anterior to it.
The electrical stimulator suggested for this operation is capable of delivering a range of current intensity from 20 to 240 milliamps, which is sufficient for the purpose of these operations in the author's experience.
Illustration of incision
line in PSARP for males.
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Suggested electrical
stimulator for
PSARP operation.
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High intensity stimulation (100 to 240 mA) may be necessary while stimulating through the skin in cases of older patients with significant amounts of scar tissue. Much lower intensity (20 to 40 mA) suffices in primary operations, particularly when stimulating directly on the muscle.
As one continues with this incision, one will be able to identify the parasagittal fibers. Every effort should be made to remain exactly in the midline. For this, use of the electrical stimulator seems to be particularly useful for assuring that the magnitude of the muscle contraction is the same on each side of the midline.
The figure below on the left shows the parasagittal fibers before the incision is extended across the center of the external sphincter. The vertical fibers (muscle complex) are not shown there because they are only located within the limits of the external sphincter.
The illustration above on the right shows the typical findings once we have continued our incision anteriorly through the center of the sphincter. Now the vertical fibers that continue deep into the subcutaneous tissue can be seen.
Following those fibers will lead to the levator muscle, in a later stage of the operation. The vertical fibers finish at the skin level and run perpendicular to the parasagittal fibers. The crossing of those vertical fibers with the parasagittal ones marks the posterior limit of the new anus.
The above figures shows the continuation of the incision anterior to the center of the external sphincter. Now it is easy to see the anterior limit of the external sphincter which is the point where the anterior edge of the "muscle complex" (vertical fibers) cross perpendicularly to the parasagittal fibers; that point will become the anterior limit of the new anus.
Remember that the vertical fibers are always medial to the parasagittal fibers. The thickness of those vertical fibers as measured in lateral dimension is usually not greater than 3mm, and, therefore, care must be taken to split these fibers exactly in the middle, leaving an equal amount of muscle on each side of the future anus. As the incision is extended anteriorly, the fat of the perineal body can be seen.
At the same time, by continuing to cut deeper into the subcutaneous tissue, the levator muscle is exposed.
Once the coccyx has been exposed, the needle tip cautery is used to split it exactly in the midline. The entire procedure is carried out with a needle tip cautery which allows for meticulous hemostasis.
The little vessels are cauterized in a precise manner to avoid unnecessary burning of the tissues. Working mainly in a dry field allows the surgeon to identify every single structure.
Once the coccyx has been split, the levator muscle can be divided beginning from cephalad to caudad. For this, we use a baby right-angle clamp which is introduced in front of the levator muscle at the level of the coccyx.
We then split the muscle between the arms of our baby right-angle clamp in order to remain exactly in the midline. All the striated muscle structures must be divided in order to identify the posterior rectal wall.
Examining the posterior rectal wall does not indicate where the urethra starts and where the rectum ends.
The preoperative distal colostogram gives us a precise clue of the type of defect we are dealing with.
This figure below illustrates the operative findings in a typical rectourethral bulbar fistula. The deepest point in this figure most likely represents the transition point between rectum and urethra.
For more information or to request an appointment, please contact the Colorectal Center at Cincinnati Children's.
