A. Internal<unk>  intussusception. B. External (complete)<unk>  The different kinds of<unk>  can be difficult to grasp, as different definitions are used and some recognize some subtypes and others do not. Essentially,<unk> s may be *full thickness (complete), where all the layers of the<unk>  wall<unk> , or involve the mucosal layer only (partial) *external if they protrude from the anus and are visible externally, or internal if they do not *circumferential, where the whole circumference of the<unk>  wall<unk> , or segmental if only parts of the circumference of the<unk>  wall<unk>  *present at rest, or occurring during straining. External (complete)<unk> <unk>  procidentia, full thickness<unk> , external<unk>  is a full thickness, circumferential, true intussusception of the<unk>  wall which protrudes from the anus and is visible externally. Internal<unk>  intussusception (occult<unk> , internal procidentia) can be defined as a funnel shaped infolding of the upper<unk>  (or lower sigmoid) wall that can occur during defecation. This infolding is perhaps best visualised as folding a sock inside out, creating "a tube within a tube". Another definition is "where the rectum collapses but does not exit the anus". Many sources differentiate between internal<unk>  intussusception and mucosal<unk> , implying that the former is a full thickness<unk>  of<unk>  wall. However, a publication by the American Society of Colon and<unk>  Surgeons stated that internal<unk>  intussusception involved the mucosal and submucosal layers separating from the underlying muscularis mucosa layer attachments, resulting in the separated portion of<unk>  lining "sliding" down. This may signify that authors use the terms internal<unk>  and internal mucosal<unk>  to describe the same phenomena. Mucosal<unk>  (partial<unk>  mucosal<unk>  refers to<unk>  of the loosening of the submucosal attachments to the muscularis propria of the distal rectummucosal layer of the<unk>  wall. Most sources define mucosal<unk>  as an external, segmental<unk>  which is easily confused with<unk> d (3rd or 4th degree) hemorrhoids (piles). However, both internal mucosal<unk>  (see below) and circumferential mucosal<unk>  are described by some. Others do not consider mucosal<unk>  a true form of<unk> . Internal mucosal<unk> <unk>  internal mucosal<unk> , RIMP) refers to<unk>  of the mucosal layer of the<unk>  wall which does not protrude externally. There is some controversy surrounding this condition as to its relationship with hemorrhoidal disease, or whether it is a separate entity. The term "mucosal hemorrhoidal<unk> " is also used. Solitary<unk>  ulcer syndrome (SRUS, solitary<unk>  ulcer, SRU) occurs with internal<unk>  intussusception and is part of the spectrum of<unk>  conditions. It describes ulceration of the<unk>  lining caused by repeated frictional damage as the internal intussusception is forced into the anal canal during straining. SRUS can be considered a consequence of internal intussusception, which can be demonstrated in 94% of cases. Mucosal<unk>  syndrome (MPS) is recognized by some. It includes solitary<unk>  ulcer syndrome,<unk> , proctitis cystica profunda, and inflammatory polyps. It is classified as a chronic benign inflammatory disorder.<unk>  and internal<unk>  intussusception has been classified according to the size of the<unk> d section of rectum, a function of<unk>  mobility from the sacrum and infolding of the rectum. This classification also takes into account sphincter relaxation: * Grade I: nonrelaxation of the sphincter mechanism (anismus) * Grade II: mild intussusception * Grade III: moderate intussusception * Grade IV: severe intussusception * Grade V:<unk><unk>  internal mucosal<unk>  has been graded according to the level of descent of the intussusceptum, which was predictive of symptom severity: * first degree<unk>  is detectable below the anorectal ring on straining * second degree when it reached the dentate line * third degree when it reached the anal verge A. Normal anatomy: (r) rectum, (a) anal canal B. Recto-rectal intussusception C. Recto-anal intussusception The most widely used classification of internal<unk>  is according to the height on the<unk> /sigmoid wall from which they originate and by whether the intussusceptum remains within the rectum or extends into the anal canal. The height of intussusception from the anal canal is usually estimated by defecography. Recto-rectal (high) intussusception (intra-rectal intussusception) is where the intussusception starts in the rectum, does not protrude into the anal canal, but stays within the rectum. (i.e. the intussusceptum originates in the rectum and does not extend into the anal canal. The intussuscipiens includes<unk>  lumen distal to the intussusceptum only). These are usually intussusceptions that originate in the upper rectum or lower sigmoid. Recto-anal (low) intussusception (intra-anal intussusception) is where the intussusception starts in the rectum and protrudes into the anal canal (i.e. the intussusceptum originates in the rectum, and the intussuscipiens includes part of the anal canal) An Anatomico-Functional Classification of internal<unk>  intussusception has been described, with the argument that other factors apart from the height of intussusception above the anal canal appear to be important to predict symptomology. The parameters of this classification are anatomic descent, diameter of intussuscepted bowel, associated<unk>  hyposensitivity and associated delayed colonic transit: * Type 1: Internal recto-rectal intussusception *Type 1W Wide lumen *Type 1N Narrowed lumen *Type 2: Internal recto-anal intussusception *Type 2W Wide Lumen *Type 2N Narrowed lumen *Type 2M Narrowed internal lumen with associated<unk>  hyposensitivity or early megarectum *Type 3: Internal-external recto-anal intussusception
Rectal prolapse
Pelvic organ prolapse
Anal fistula
Vesicovaginal fistula
Anal fissure
Perianal cellulitis
Rectovaginal fistula
Anorectal abscess