fistula
瘻 centers on an abnormal passage or connection in the body: a fistula. The other given meanings (hunchback, sore, boil) are less common and may reflect related pathological swellings or lesions, but the primary medical sense is a fistula.
瘻 combines 疒 (sickness) with 婁, which likely contributes the sound. The character originally referred to a hunchback or swelling, later extended to fistula in medical contexts. The exact historical development of the inner component is uncertain.
The sickness enclosure 疒 wraps around 婁, which looks like a twisted, knotted shape. Picture a diseased, tunnel-like passage forming under the skin, like a fistula connecting two areas.
For ル, imagine a loop-shaped fistula: loop -> ル, and the sickness enclosure contains this looping passage.
obstetric fistula
fistula
fistula
rectovaginal fistula
percutaneous endoscopic gastrostomy; PEG