Percutaneous Obliteration of Patent Processus VaginalisA Rat Model for Future Inguinal Hernia Repair in Children

Yassir Assiri, Saad Al-Kahtani5th year medical student

KSU

Inguinal Hernia Repair in Children

• Inguinal hernia affects 3.5-5% of all full term infants and 9-11% of premature babies

• Hernia surgery is one of the commonest procedures performed by pediatric surgeons Glick PL , 2007

• Failure of in-utero Processus Vaginalis obliteration is believed to be the main pathology

(PPV)

Seen#2 (still photo): normal closed canal (processus vaginalis)

Current options for treating symptomatic Patent Processus Vaginalis (PPV) in children

1. Open inguinal herniotomy (most popular) Ein SH, 2006 & Vogels HD 2010

– Painful inguinal incision– Possible injury to vas deference and testicular vessels – Risk of chronic pain and numbness due to ileo-inguinal nerve injury

2. Laparoscopic hernia repair Schier F,2002 & Chan KL, 2007

– Higher recurrence rates– Postoperative hydrocele formation– Possible injury to the vas and gonadal vessels– Higher cost concerns. McCormack K, 2005

3. Mini-scar inguinal herniotomy Al-Jazaeri et al, 2011

– Small incision but difficult to perform– Not for all children– Risk of vas & vessels injury

Per-cutaneous approach has been the natural evolution for many open surgeries

• Deep cavity abscess drainage• Coronary stenting • Cerebral aneurysm treatment • Fetal intervention (PUV, Twins transfusion..)• Tumor ablation and embolization (liver, kidney,..)• Aortic Aneurysm repair• Heart valve replacement

…and the list is growing

Percutaneous Obliteration of Patent Processus Vaginalis

(PO-PPV)A Possible

Future Model for Inguinal Hernia Repair in

Children

The Current Challenges…• How to access the thin PPV?

- Very thin membrane- Collapsed

• How to avoid injuring other structures while accessing PPV?-Bowel -Vas deference-Testicular vessels

• How to effectively obliterate the PPV ?- Achieve a complete closure- Avoid recurrence

The concept of our experimental design…Percutaneous Obliteration of PPV (PO-PPV)

Inflate PPV with air

Per-cutaneous access

Inject tissue adhesive

Obliterated PPV

Cannula (V.needle) pneumo-

peritoneum

Insert a cannula while

aspirating

2-octyl-cyanoacrylate

radiological & histological

analysis

The adhesive molecule2-Octyl-Cyanoacrylat (2-OC)

2-OC + H2O Polymerization=> Adhesive effect

Liquid Plastic-like bonding molecule

Insufflators

Our poor patient….

Inducing pneumoperitonium

Intra-peritoneal cannula insertionCannula is introduced while aspirating

Air indicates intra-peritoneal position

In future human model the cannula can be introduced directly into the inflated inguinal canal

Inflated abdomen

The cannula is advanced through the PPV

Two cannulas are used for bilateral PO-PPV

2-OC is injected inside the PPV while

2-OC (blue)

External pressure is applied to prevent

intra-abdominal leak

Two cannulas are used for bilateral PPV obliteration

Air is then injected to minimize rapid polymerization of 2-OC by the peritoneal H2O

External pressure is maintained for 5-min

Experimental Groups

4 weeks old Lewis rats

Unilateral PO-PPV(n=11)

Bilateral PO-PPV(n=15)

Sham (saline injected)

(n=14)

Outcomes …

• Effectiveness (PPV obliteration)– Herniography– Gross post-mortum inspection

• Safety of vas & testicular tissue– Post-mortum hitological analysis

• Vas patency• Testicular changes

– Treatment group fertility

The Experimental Timetable

Week #4 •Procedure (PO-PPV)

Week #6 •Mating

Week #8 •Herniograpahy

Week # 12 •Sacrificed -> histology Rat age

IRB approval

Herniography…

Effectiveness (PPV obliteration)

Shame group

Herniography

Contrast is seen around testis due

to Patent PV

Sham group

Shame group

Herniography

Contrast is passing through PPV

Sham group

Herniography Obliterated PV

Patent PV

Unilateral PIH group

Herniography

Unilateral PIH group

Herniography

Unilateral PIH group

Bilateral PPV obliteration

Herniography

Obliterated PV

Contrast filled abdomen

Bilateral PIH group

Bilateral PPV obliteration

Herniography

Bilateral PIH group

Obliterated PV

Effectiveness (PPV obliteration)

Sides Sham (n=14) Unilateral (n=11) Bilateral (n=30)

PPV Obliteration

Herniography (sides) 0 11 (100%) 25 (83.3%)

Post-mortum PV analysis (sides)

0 11 (100%) 30 (100%)

Both sides are treated

Histology…

Safety...

Histological Analysis Sham (n=14) Unilat (n=12) Bil (n=30)

Fibrosis

None 14 12 28 Moderate 0 1 2 Sever 0 0 0Fat necrosis

None 13 1 4 Moderate 1 8 13 Sever 0 3 13FB reaction

None 13 1 4 Moderate 1 8 13 Sever 0 3 13Vas patency (gross&histology)

Patent 14 12 30 Narrowed 0 0 0 Obliterated 0 0 0

Normal vas deferens mucosa and muscular wall.

Normal and patent Vas Deferens with a focus of gaint cells reaction

Calcification

CalcificationCalcification

A co

rd o

f gia

nt ce

lls

Safety...Fertility (mating)

+X1 Boy X 2 Girls

All rats were fertile after mating

Safety...Fertility (mating)

Limitations and future plansChallenges Solution / Alternative Strategy

Rapid polymerization in H2O (peritoneal fluid)

Marine Biomimetics Adhesives

Low viscosity intra-peritoneal leak Mix with alginate (inert thickening agent derived from seaweed)

Safety of foreign body inflammatory reaction induced by 2-OC?

Mesh has long track record of safety in adult inguinal hernia

Long term effectiveness and safety Larger animal model and long follow up is needed

Marine Mussel Adhesion

The future of tissue adhesives

blue mussel, Mytilus edulis

Produce adhesives that work in aquatic environment

Wide potential applications in surgery and dentistry

ConclusionPer-cutaneous obliteration of PPV is possible and safe

in animal

Some challenges have to be addressed before the safe and effective transfer to human

Percutaneous hernia repair is likely to be the next step in the evolution of hernia repair

for both children and adults

Thank youSimplified Animation….

References• Glick PL, Boulanger SC. Inguinal hernias and hydroceles. In: O'Neill JA, Rowe MI, Grosfeld JC, et

al, editors. Pediatric surgery, 5th edn, Mosby, St Louis 2007, 1172-92.• Ein SH, Njere I, Ein A. Six thousand three hundred sixty-one pediatric inguinal hernias: a 35 year

review. J Pediatr Surg 2006;41:980–6• Vogels HD, Bruijnen CJ, Beasley SW. Establishing benchmarks for the outcome of herniotomy in

children. Br J Surg 2010;97:1135-9• Schier F, Montupet P, Esposito C. Laparoscopic inguinal herniorrhaphy in children: a three-center

experience with 933 repairs. J Pediatr Surg 2002;37:395-7.• Chan KL, Chan HY, Tam PK. Towards a near-zero recurrence rate in laparoscopic inguinal hernia

repair for pediatric patients of all ages. J Pediatr Surg 2007;42:1993-7.• McCormack K, Wake B, Perez J, Fraser C, Cook J, McIntosh E, et al. Laparoscopic surgery for

inguinal hernia repair: systematic review of effectiveness and economic evaluation. Health Technol Assess. 2005;9:1–203, iii–iv.

• Al-Jazaeri A, Al-Hassan N, Al-Hassan B, Harakati D, Al-Hezayen R, Al-Zahem A. Mini-Scar Inguinal Herniotomy in Selected Children: Comparative Analysis of Safety, Effectiveness and Parents’ Satisfaction. J Laparoendo surg tech, 2011

• Silverman HG, Roberto FF. Understanding Marine Mussel Adhesion. Mar Biotechnol (NY). 2007 December; 9(6): 661–681.