Friday, November 28, 2008

rumenotomy procedure at a glance

    Surgical opening of the rumen by making the incision on the wall of rumen is known as rumenotomy. Rumenotomy is a routine procedure for treating many diseases in ruminants.
    a) Persistant ruminal impaction.
    b) Frothy Bloat.
    c) Foreign bodies lodged in distal esophagus, rumen, and reticulum.
    d) Traumatic reticulitis.
    e) Atony of omasum and abomasum.
    f) Reticular herniorraphy.
    g) Exploratory rumenotomy for diagnosis of intraruminal diseases. other than foreign bodies.
    h) Ingestion of toxic plants.
    i) Diaphragmatic hernia.
    Site of incision
    The site of incision is
    · Left mid flank vertical incision.
    · In case of traumatic reticulitis in large size animal the site of incision is parallel to last rib.
    · The site of incision is usually equidistant from tubercoxae and the last rib beginning 5 cm ventral to the lumbar transverse process.

    Anatomical considerations
    1. Rumen occupies almost left half of the abdominal cavity from 7th or 8th intercostal space to the pelvic inlet and extend over the medial plane to the right side ventrally.

    2. The rumen is marked on its parietal (left) and visceral (right) surface by longitudinal, anterior and posterior grooves. These grooves divide the rumen into dorsal and ventral sacs, anterior and posterior blind sacs. The rumen is generally opened for rumenotomy through dorsal sac of rumen.
    3. Different structures encountered during rumenotomy are:
  • skin
  • subcutis and subcutaneous fat
  • external oblique muscle, fibres of which passes somewhat downward and backward
  • ·internal oblique muscle, fibres of which pass downward and forward
    transverses abdominis, which is thin and fibres extends in perpendicular direction
  • ·deep iliac fascia
  • ·subperitoneal fat
  • parietal layer of peritoneum
  • rumen wall
    4. While dividing these structures in this region 1st and 2nd lumbar nerves which runs nearly perpendicular in direction are encountered.
    5. The blood supply to flank is contributed by deep circumflex iliac and phrenico-abdominal vessels. The blood vascular channels of the rumen are located in the left and right longitudinal grooves and anterior and posterior transverse grooves of it.

Premedication and anaesthesia
The rumenotomy operation is performed in standing position. The desensitization of flank area with animal in standing position can be achieved by:
1. Inverted ‘L’ block
2. Field block
3. Paravertebral anaesthesia

v In most of the animals Paravertebral anaesthesia is used and for this T13, 1L and L2 nerves are blocked.
v Although usually local anaesthesia of the flank and Paravertebral block is sufficient for rumenotomy, however in non cooperative animals tranquilization may be required.

Preparation of site
1. The whole dorsum of left abdominal wall should be thoroughly cleaned with soap and water to remove all the dirt and dust before further preparation for surgery is done followed by shaving of left flank with surrounding area.
2. Scrubbing should be done.
3. Again clean with soap and water.
4. Apply 70% isopropyl alcohol to the incision site.
5. After that tincture iodine is painted over the site.
6. Drapes are put over the site leaving the proposed site of incision.
7. The bars of trevis, used to control the animal, which immediately faces the surgeon should be covered with sterile sheets and drapes.
Surgical procedure
Upper flank laparotomy:
1. The skin is incised with a smooth but firm motion. The pressure on the scalpel should be adequate enough to ensure complete penetration of the skin.
2. Dissection of the subcutaneous fascia and oblique muscles continues to expose the glistening aponeurosis of transverse abdominis muscle.
3. Different muscles from outside to inside are incised one by one along with their fascia after grasping them with Allis tissue forceps. In the last peritoneum is grasped with allis tissue forceps and then it is incised taking care not to cause any injury to underlying rumen.
4. The length of incision from skin to the peritoneum should be in descending order to facilitate closure.
5. The skin incision should be long enough to allow the surgeon’s arm inside the abdomen.
6. If the rumen is not full, the walls of rumen and abdomen separate out spontaneously to facilitate exploration.
7. The abdominal cavity should be thoroughly explored to examine the wall of diaphragm, outer wall of reticulum, spleen and liver for any pathological lesion.
8. A thorough search is made by inserting hand in the abdominal cavity through the incision and rolling over the rumen on all sides to rule out any herniation, abcessation or foreign bodies.
9. No attempt should be made to break down the firm adhesions if present.

v If the rumen is grossly distended, aspiration is done by piercing a 16” needle on dorsal aspect.
v A fold of rumen is exteriorized. For better exteriorization, retention and to avoid contamination of abdominal cavity with ruminal contents, several ruminal fixation techniques are used such as:

A. Stay suture technique:
After laparotomy, the rumen has to be pulled out gently out of the laparotomy incision and rumen walls were anchored to the incision dorsally, ventrally, cranially and caudally by placing four or more sutures between ruminal walls and skin by using no.2 silk or nylon as suture material.

B. Rumen skin fixation sutures technique:
After rumenotomy the rumen wall can be fixed to the skin incision by a continuous inverting suture pattern to pull the rumen over the edges of the skin incision.

C. Weingarth ring technique:
Following laparotomy, a Weingarth ring is fixed to the dorsal commisure of the incision by its thumb screw. The rumen is fixed to the ring. As the rumen wall is incised hooks are placed into cut edges of ruminal wall, pulled out and hooked around the frame until the rumen had been reflected outward all the way around the incisio

D. Rumen skin clamp fixation technique:
The rumen is incised and fixed with skin on either side with the help of towel clamps.

E. McLintock’s sheet and ring fixator.
Here ruminal incision can be fixed with rubber shroud. The ruminal wall is held outside the incision by using a rubber ring.

v After fixation, the rumen is incised longitudinally in the vertical direction on the dorsal compartment
v In case, if the rumen is full of large amount of liquid digested material, a very large diameter stomach tube can be used to siphon off the content of rumen to allow the exploration of other chambers.
v In case of coarse material manual removal is done.
v Maximum 80% of the ruminal contents may be evacuated. If complete rumen is emptied fresh cud or microflora should be kept in rumen before its closure.
v The hand is then inserted in the rumen and entire rumen, reticulum, reticulo-ruminal fold and esophageal groove are searched out and if any foreign body is present, it is removed.
v A magnet may be introduced and swept over rumen and reticulum to retrieve any metallic substance.
v After surgical intervention the surgeon rescrubs his hands and the edges of rumen incision are thoroughly cleaned and redrapped.
v The rumen incision is closed by double row of continuous inverting sutures using chromic catgut no. 2 or 3.
v The suture site and exposed area is irrigated with polyionic fluids with or without antiseptic solution.
v Rumen fixation instruments or sutures are removed and all the soiled substances are discarded.
v The surgeon scrubs again before starting the suturing of peritoneum, muscle and skin incision.
Closure of laparotomy incision:
v A flank laparotomy incision can be sutured in different layers depending on the preference of surgeon. Most preffered method is closure in 4 layers.
v The 1st layer of a simple continuous suture is applied using no 2 or 3 catgut on peritoneum and transverse abdominis muscle.
v The two oblique muscle are sutured together in 2nd layer with catgut or silk No. 2.
v Subcuticular sutures are applied to bring the opposite edges of skin near to each other and to obliterate dead space.
v Suturing of skin by placing series of simple interrupted or interrupted mattress sutures leaving 3-4 stay sutures to apply the gauge piece or bandage piece to cover the wound.
Post operative care
Ø Course of antibiotic coverage for 5-7 days.
Ø Anti inflammatory/analgesics drugs for 2-3 days
Ø Dressing on alternate days for 7-10 days
Ø Fluid therapy, if required.
Ø Mild osmotic laxative, may assist in prompting gut motility
Ø Light diet to animal for few days after the surgery
Ø Removal of Skin sutures on 8th to 10th day post operation day.