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Congenital and Traumatic Anorectal diseases

1. TRAUMATIC DISEASES

Etiology

  • Falling on a pointed object in a sitting position
  • Penetrating injury
  • Sexual assault or activity involving the anus
  • Foetal head injury during childbirth – using forceps

Diagnosis

  • Anus inspected and abdomen palpated
  • If abdomen is rigid – do laparotomy
  • Use water soluble contrast enema and/or CT – to visualise perforation

Treatment

  • Perforation – under general anaesthesia use finger and speculum or laparotomy
  • Intraperitoneal rupture of rectum – suture
  • Colostomy in left iliac fossa after closing laparotomy wound
  • If rectum severely damaged – resection (Hartmann’s procedure)
  • Sphincter function must be preserved
  • Antibiotics

2. CONGENITAL ABNORMALITIES

Anal atresia (imperforate anus)

  • There is no opening/stenosis of the anus
  • It can be high or low depending on site of rectal termination in relation to the pelvic floor
  • Low defects (easy to correct) – more common boys, rectourethral fistula seen
  • High defects (difficult to correct) – girls, imperforate anus with fistula opening in posterior vestibule

In girls

  • Anal opening is missing/closed off
  • Opening is in wrong place and too small
  • Rectum connects to vagina
  • Cloaca –  a posterior orifice that serves as the only opening for the digestive, reproductive, and urinary tracts

In boys

  • Anal opening is missing/closed off
  • Opening is in wrong place and too small
  • Rectum connects to urethra/bladder
  • High rectum connects into bladder – poor prognosis

Clinical features/investigations

  • Perineal exam
  • Meconium on perineum – low defect
  • Meconium in urine – urinary tract fistula
  • First 24hrs – IV fluids, antibiotics, monitor for other congenital abnormalities (VACTERL anomalies)
  • Lateral prone XR – distal limit of air within rectum (indicates distance between rectal stump and perineum)
    • To differentiate between low and high malformation

Treatment

  • Low abnormalities or perineal fistula – anoplasty
    • 1o neonatal pull-through without colostomy – if perineal fistula or closed rectal pouch seen on pelvic XR
    • Cystoscopy – rule out malformation
  • Complex malformation
    • Early colostomy (temporary) followed by definitive repair several months later
    • Left lower quadrant incision – large colon divided at point where descending colon meets sigmoid colon. Both ends brought to abdominal wall
    • Later operation – large portion of colon is available to bring down to perineal skin

Post anal dermoid

  • Cystic soft tissue swelling in front of lower part of sacrum and coccyx
  • Not often discovered unless inflamed
  • Clinical features begin in adult life – difficult defecation
  • Palpable on rectal exam
  • Treatment – excision
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