Embryologie des Malformations Ano-Rectales

Presentation Title

• Topic: Ano-rectal Malformations (MAR)
• Presenter: OUEDRAOGO Judion
• Degree: DES II in General Surgery
• Supervisor: Pr OUEDRAOGO Isso

Objectives

• Define MAR
• Explain the pathophysiology of fistula formation in MAR
• Establish a positive diagnosis
• Interpret the Invertogram
• Provide treatment guidelines for MAR

Plan

• General Information
  • Definition
  • Interest
  • Historical background
  • Embryological review
  • Anatomical review
  • Physiology
  • Physiopathology
  • Signs
  • Types of Disease (TDD)
  • Clinical Forms
• Diagnostic
  • Positive Diagnosis
  • Differential Diagnosis
• Treatment
  • Goals
  • Methods and Resources
  • Indications
• Conclusion
• Bibliography

General Information - Definition

• Congenital anomalies
• Partially or completely interrupting the terminal portion of the digestive tract
• Modifying its topographical characteristics

General Information - Interest

• Epidemiological
• Prevalence: 1 in 5000 births
• Predominance: male

General Information - Historical Background

• Known since antiquity
• Treated by trocarization and successive dilations
• 1835: Amussat performed the first proctoplasty
• 1982: Pena and De Vries synthesized PEC Forms for MAR

General Information - Embryological Review

• The primitive digestive tube has three zones
  • Anterior intestine
  • Middle intestine, connected to the umbilical vesicle by the vitelline duct
  • Posterior intestine (1/3 distal of the colon, transverse colon, descending colon, sigmoid colon, rectum, upper part of the anal canal)

General Information - Embryological Review (Continued)

• The posterior intestine participates in the formation of the urogenital sinus
• The posterior part opens into the cloaca, which receives the allantoid diverticulum
• The cloaca extends into the caudal intestine (post-natal)

General Information - Embryogenesis (Ano-Pelvi-Rectal)

• 4th and 10th gestational weeks
• 3 stages:
  • Formation of the cloaca and primary perineum (4th week)
  • Cloaca segmentation (7th week)
  • Anal canal canalization (10th week)

General Information - Embryology of MAR

• Membranous perforations: Persistence of the anal membrane
• Covered anus: Fusion of the anogenital folds forward
• Urogenital or skin communications: Incomplete fusion of the urogenital and rectal partitions

General Information - Anatomical Review

• Rectum
• Sigmoid Colon
• Anal Ampulla
• Anal Canal
• Ano-cutaneous Junction

General Information - Sphincteric Apparatus

• Sphincter internus
• Sphincter externus

General Information - Vascularization

• Superior mesenteric artery
• Inferior mesenteric artery
• Common Iliac artery
• Internal Iliac artery
• Middle sacral artery

General Information - Innervation

• The control of continence involves several components

General Information - Physiology- Continence Mechanism

• Puborectal muscle
• Iliococcygeus muscle
• Ischiococcygeus muscle
• Pubococcygeus muscle
• Internal smooth muscle
• External striated muscle

General Information - Physiology- Continence Mechanism (Continued)

• Rectal-anal sensitivity
• Voluntary motor control (external sphincter and levator ani muscles)
• Involuntary motor control (internal sphincter)
• Coordination (rectosigmoid motility)

General Information - Physiology - Other Factors

• Rectal adaptability
• External pressure: Pelvic floor and intra-abdominal pressures
• Intrinstic pressures: Pelvic floor and two sphincters

General Information - Physiology - Systems.

• Capacity system (rectums ability to adapt to its content)
• Resistance system (anal canal's resistance to passage of stools, basal tone, defecation efforts).

General Information - Physiology- Resistant Organ

• Internal sphincter: Permanent pressure barrier
• External sphincter: Emergency continence
• Levator ani muscles: Maintains anorectal angulation

General Information - Defecation

• Cortical centers sense rectal fullness and need
• Relaxation: Internal or recto-anal inhibitory reflex
• Conscious and voluntary contraction of the external sphincter and puborectal muscle
• Stools are stopped at the upper part of the anal canal

General Information - Pathophysiology

• Interruption of digestive continuity: obstruction of meconium expulsion
• Partial: Fistula
  • Skin of the perineum
  • Vulva or vagina
  • Recto-genital fistula
  • Blatter or urethra
  • Recto-urinary fistula
• Total: Neonatal occlusion
  • Absence of meconium emission
  • Abdominal distension
  • Vomiting (green mucus)
  • Fluid sequestration
  • Microbial overgrowth
  • Hypovolemic and septic shock

General Information - Signs

• TDD: MAR/recto-urinary fistula in a male newborn
• CDD variables
  • Neonatal perianal examination
  • Parent's account: Absence of anus
  • Functional triad in newborns
    • Absence of meconium emission
    • Abdominal distention
    • Bilious vomiting

General Information - Signs (Continued)

• General signs:
  • General state deterioration
  • Fontanelle depression
  • Persistent skin fold, secondary to vomiting
• Physical signs:
  • Abdominal distension
  • Collateral venous circulation
  • Absence of an anal opening
• Physical Signs (Continued)
• Search for related abnormalities: urogenital and spinal cord

General Information - Signs (Para-clinical)

• Imaging
  • Precise anatomical type
  • Identification of possible fistula (urinary, vaginal, or perineal)
  • Detect associated abnormalities.
  • Visualize the rectal ampulla
  • Precise the level of rectal cul-de-sac

General Information - Signs (Para-clinical)- Imaging (Invertogram)

• Performed 12 hours after birth
• Child in head-down position for at least 5 minutes
• Knees bent at 90°
• Placement of a metallic marker on the anal fossa
• Locate the position of the rectal cul-de-sac in relation to the levator ani muscles and anal fossa.

General Information - Signs (Para-clinical)- Opacifications

• Fistulography
• Colostography

General Information - Signs (Para-clinical) - Ponction Opacification

• Perineal area without fistula
• Transperineal puncture of the cul-de-sac with a fine needle under fluoroscopic guidance
• Opacification with a soluble iodine product

General Information - Signs (Para-clinical) - Additional Imaging Techniques

• MRI of the perineum
• CT of the perineum
• Retrograde cystography

General Information - Signs (Para-clinical) - Additional Imaging Techniques (Continued)

• Urography
• Preoperative endoscopy

General Information - Signs (Para-clinical) - Additional Assessment

• Ultrasound and MRI of the kidneys, to detect abnormalities.
• Ultrasound and MRI of the spinal cord, search for dysraphism, low spinal cord, presacral mass, compatible with Currarino syndrome.
• Echocardiography
• Karyotype study, in case of suspected genetic abnormalities

General Information - Signs (Biological)

• Complete blood count (CBC)
• Blood typing and Rh factor
• Blood electrolytes
• Blood urea nitrogen (BUN) and creatinine
• Assessment of renal function

General Information - Evolution (Non-Treated)

• Continuous abdominal distension
• Vomiting (green)
• Fluid sequestration
• Bacterial overgrowth (origin)
• Hypovolemic and septic shock

General Information - Clinical Forms

• Symptomatic forms
  • Occlusive forms (without fistulae)
  • Insufficient fistulae
  • Non-occlusive forms (sufficient fistula caliber)
    • Stools are softer
• Anatomical (high) forms
  • Male: anorectal atresia, recto-urinary fistula
  • Female: anorectal atresia, recto-vaginal fistula
• Anatomical (intermediate) forms
  • Male: anal atresia, recto-bulbar fistula
  • Female: anal atresia, recto-vestibular fistula
• Anatomical (low) forms
  • Male: perineal fistula.
  • Female: anal stenosis, perineal fistula

General Information - Clinical Forms (Continued)

• Cloacal forms
  • Short cloaca, low MAR (communicating colon < 3cm)
  • Long cloaca, low MAR (communicating colon > 3cm)

General Information - Associated Malformations

• VACTERL association
  • Vertebral anomalies
  • Anorectal anomalies
  • Cardiac anomalies
  • Tracheal anomalies
  • Esophageal anomalies
  • Renal anomalies
  • Limb anomalies
• Pallister-Hall syndrome
• Pallister-Killian syndrome

General Information - Associated Malformations (Continued)

• Currarino syndrome
• MURCS association
  • Müllerian duct anomalies
  • Renal and/or reproductive tract anomalies
  • Cervical and thoracic organ abnormalities

General Information - Chromosomal Abnormalities

• "Cat Eye" syndrome (chromosome 22 duplication/inversion)
• Coloboma of the iris

Diagnostic - Positive Diagnosis

• Lack of an anus or abnormal anus in the perineum
• Recto-urinary fistula in males, recto-vaginal in females

Diagnostic - Imaging

• ASP Wagensteen-Rice
• Direct or fistulographic opacification of the rectal cul-de-sac

Treatment - Goals

• Save the patient's life
• Emptying stools
• Restructuring the anorectal or anocutaneous continuity
• Achieve socially acceptable anal continence
• Preventing and treating complications

Treatment - Medical Means

• Hospitalization
• Peripheral intravenous line
• Urinary and/or gastric catheterization
• Pre- and post-operative fluid and electrolyte replacement (100 ml/kg)
• Analgesics: paracetamol (15 mg/kg every 6 hours)
• Antibiotic: ceftriaxone (80 mg/kg daily)

Treatment - Medical Means (Continued)

• Vitamin K1
• Patient warming

Treatment - Surgical Means - Temporary

• Principles: Temporary diversion of the digestive tract
• Colorectal resection
• Performed Neonatally
• Location: Transverse or sigmoid colon
• Positioning: Horizontal line through the umbilicus, away from the costal margin and iliac crest

Treatment - Surgical Means - Temporary (Continued)

• Advantages: Life-saving
• Covers future surgical repair
• Distal cologram to aid in determining exact location of fistula.
• Reduces risk of prolapse
• Disadvantages: Parent acceptance issues.

Treatment - Surgical Means - Definitive

• Principles: Rectal lowering to its presumed anatomic level
• Preservation of rectal vascularization
• Creation of a new anus (neoanus) or (anoplasty)

Treatment - Surgical Techniques - Anoplasties

• Joining the rectal cul-de-sac to the skin
• Creation of a neoanus with an anocutaneous flap, via a perineal approach.

Treatment - Surgical Techniques - Anorectoplasties

• Types of approaches
  • Pure perineal
  • Abdominopelvic
  • Laparoscopic
• Examples:
  • Pellerin Y-V anoplasty
  • Hendren anoplasty
  • Santulli anal transposition
  • Denis Brown cut back anoplasty
  • Leape anoplasty
  • Nixon anoplasty -Douglas sacroperineal anorectoplasty -Mollard anorectoplasty -Sagittal posterior anorectoplasty(Vries)

Treatment - Indications for Specific Cases

• Low MAR with fistula
  • Perineal fistula in both sexes
  • Pellerin Y-V proctoplasty
  • Anorectal fistula in females
  • Pellerin proctoplasty
• Intermediate or high MAR without fistula
  • Colorectal resection and temporary colostomy
  • Sacroabdominal decompression, Stephans technique
  • Perineal or abdominopelvic decompression, Mollard technique
  • Sacropelvic posterior anorectoplasty(Pena)

Treatment - Indications for Specific Cases (Continued)

• Intermediate/high MAR with recto-vaginal/urinary fistula
  • Colorectal diversion (colostomy)
• Anal placement
  • "Y-V" Pellerin anoplasty by lambeau.
• Low MAR without fistula
  • Pellerin Y anoplasty by lambeau.

Treatment - Post-operative Follow Up

• Antibiotic prophylaxis (3-5 days)
• Follow-up (10-15 days)
• Local antiseptics
• Anal dilation with Hégar bougies (10-15 days)

Treatment - Post-operative Follow Up (Continued)

• Colorectal anastomosis (3 to 6 months)

Treatment - Complications:

• Early/late secondary complications
  • Urological (urinary fistula, urethral stenosis, ureteral damage, damage to the vas deferens)
  • Digestive (anal stenosis, anorectal mucosal eversion)
  • Genital (vaginal stenosis)
• Late complications
  • Fecal incontinence
  • Episodes of soiling
  • Constipation
  • Psychological and social issues

Conclusion

• Early MAR diagnosis is critical.
• Multidisciplinary approach in specialized settings
• Parental counseling (limitations for social continence with some compromises)
• Varying surgical techniques based on MAR type
• Good prognosis for life and acceptable function