High complex anal fistula managed by the modified transanal opening of the intersphincteric space via the inter-sphincteric approach: A case report

Table 1 Anal sphincter pressure measurements by water-perfused anorectal manometry

Measurements	Values	References (in adults)
Anal resting pressure (mmHg)	51	50-70
Anal squeeze pressure (mmHg)	143	120-170
Functional anal canal length (cm)	3.2	3.2-3.5
Delayed defecation reflex	Reversible and pressure curve decline	Reversible and pressure curve decline
Rectoanal contraction reflex	+	+
Rectoanal inhibitory reflex	10 mL lead out	5-10 mL lead out
Anal reflex diastolic pressure (mmHg)	35	> 30
The first rectal sensation (mL)	20	10-30
Volume to get an urge to defecate (mL)	100	50-80
Maximal tolerated volume (mL)	170	110-280
Rectoanal pressure during defecation (mmHg)	83	> 45

Table 2 Merits and demerits of fistulectomy vs transanal opening of the intersphincteric space vs modified transanal opening of the intersphincteric space

	Fistulectomy	TROPIS	Modified TROPIS
Surgical procedure	Remove the fistula, and surrounding muscles, fat and connective tissues	Identify the internal opening. Lay open the fistula tract in the intersphincteric plane through the transanal route. Resect the lower part of the internal sphincter. Scrap out the remaining branching fistulas	Widen the intersphincteric plane through the transanal route Identify the internal opening. A thorough drainage of fistulas passing through the intersphincteric plane. Tunnel-like fistulectomy of fistulas lateral to the external sphincter
Merits	Definite efficacy	High cure rate; small wound area; fast recovery	Easy to identify the internal opening and favor to the drainage and surgical procedure. Low risks of postoperative anal dysfunction and recurrence. Small wound area. Less pain. Fast recovery
Demerits	Large wound area; intensive pain; long recovery	Unable to clearly expose the surgical field. Not suitable for anal fistulas without a clearly identified internal opening. Not suitable for Asian people. High risks of bleeding and postoperative recurrence	Less popular. Lack of long-term follow-up data. Lack of a comparative group

TROPIS: Transanal opening of intersphincteric space.