Nephrosplenic entrapment occurs when the left portion of the large colon becomes entrapped in the space between the spleen
and the kidney. Other terms to describe this displacement are renosplenic entrapment or left dorsal displacement of the colon.
The nephrosplenic space is defined as the space formed by the left kidney, nephrosplenic ligament, dorsal edge of the spleen
and the dorsal body wall. Because the left colon is not attached to the body wall it can freely move throughout the abdomen.
The displacement is generally thought to occur secondary to gas distention lifting the left colon over the spleen. Recently,
it has been theorized that some horses with wide and deep nephrosplenic spaces are predisposed to colonic entrapment (Photo
1). In most cases, the entrapment causes a non-strangulating obstruction, and clinical signs generally include a mild intermittent
colic with a low heart rate. Rectal palpation can be variable depending on the size of the horse and the arm length of the
palpator. The most definitive finding is palpation of the colon in the nephrosplenic space. Gas distention of the colon can
make the diagnosis difficult. Medial displacement of the spleen can occur but is not pathognomonic for nephrosplenic entrapment.
Ultrasound has been beneficial in diagnosing nephrosplenic entrapment.
Photo 1: A. Spleen with a shallow nephrosplenic space. B. Spleen with a deep nephrosplenic space and recurrent nephrosplenic
Nephrosplenic space ablation
While exact incidence of the disease process is unknown, it has been reported that the entrapment or displacement has a recurrence
rate between 7 and 9 percent. Many techniques have been described to prevent recurrence of the disease process, including
resection of the colon, colopexy and nephrosplenic space ablation. Colon resection is an invasive procedure that requires
general anesthesia and predisposes the patient to contamination of the peritoneal cavity. Depending on the amount of colon
removed, nutrient absorption can be affected and a special diet required. Surgical attachment (colopexy) of the large colon
has been described for a ventral midline celiotomy and a ventral laparoscopic technique. In most cases, colopexies are reserved
for horses that are not intended athletes. However, show-hunting horses have been able to perform successfully after colopexy.
Photo 2: Incisional hernias.
Nephrosplenic space ablation has been described for a standard open approach through a seventeenth rib resection. It is a
difficult procedure with minimal visibility and a large incision. Recently, a laparoscopic approach for nephrosplenic space
ablation has been described. The technique allows better visualization of the spleen, and more complete ablation of the space
using a minimally invasive technique. The concept behind the surgery is to remove the shelf of the spleen so the colon has
nowhere to become entrapped. Regardless of technique, the colon must be reduced and placed back into normal position prior
Indications for laparoscopic nephrosplenic space ablation include horses that have displaced more than one time, young horses
that have displaced once and horses with wide, deep nephrosplenic spaces.
Photo 3: A horse in surgery with portal placement.
Signalment: An 18-year-old Hanovarian gelding that has been used for jumping and dressage.
History: The horse had five previous colic surgeries all to correct nephrosplenic entrapments.
Physical examination: The horse was in good physical condition with all parameters within normal limits. The horse had multiple body wall hernias
on ventral midline associated with previous abdominal surgeries (Photo 2).
Photo 4: The first suture bite of the surgery.
Surgical procedure: The horse was placed in a stall with food, but not water, withheld for 24 hours. Prior to surgery the horse was given 2 gm
phenylbutazone per mouth and 35 ml procaine penicillin intramuscularly. The horse was placed in stocks and sedated with xylazine
and butorphanol. The tail-head was clipped and prepared for a caudal epidural using detomidine (40 mcg/kg qs. to 12 ml with
0.9 percent saline). The left paralumbar fossa was clipped and prepared for an inverted "L" block with 2 percent lidocaine
and a focal block in the last intercostal space. The clipped area was then aseptically prepared and draped for surgery allowing
access to the last intercostal space rostrally, the transverse processes dorsally, the tuber coxae caudally and the fold of
the flank ventrally. Insufflation of the abdomen was achieved by placing a mare urinary catheter through a skin incision (instrument
portal 2) into the abdomen and attaching it to an electric CO2 insufflator. The abdomen was insufflated to a pressure of 15
mmHg. Three instrument portals were used: the first in the last intercostal space at the level of the tuber coxae, the second
at the same level between the last rib and the tuber coxae, and the third 5-cm ventral to the second portal (Photo 3). Eleven-millimeter
cannulas were used in the first and second portals and a specially designed 35-mm polyvinylchloride tube was used for the
third portal. The large-diameter cannula is fitted with threads in the rostral portion to help pull the peritoneum onto the
cannula. A groove at the end of the threads holds the peritoneum in place. The first two portals were used for the telescope
and a needle holder; the third portal was used for needle movement into and out of the abdomen. The suture material preferred
by the author is size 0 Maxon; 30-inch looped suture (effective length 60 inches) on a T-60 taper needle (Photo 4). One arm
of the suture is cut at the needle and a loop is tied in the tail of the suture material.
After all of the cannulas have been placed, the insufflation is discontinued. The spleen serves to keep the intestine away
from the surgical area rendering insufflation unnecessary. However, the surgeon must be careful when inserting the needle
to minimize puncture of bowel caudal to the kidney. The telescope is placed in the second portal and a needle holder in the
first portal. The needle is grasped in a second needle holder and introduced into the peritoneal cavity through the large
cannula. The needle is repositioned once it is in the abdomen and placed through the peritoneum adjacent to the kidney and
the splenic capsule as far rostral as possible. The needle is then placed through the loop that was previously tied (Photo
4). Tension should be kept on the suture line at all times to prevent it from loosening. The needle should be removed from
the abdomen at each bite to reduce the chance of tying knots inadvertently. Suture bites are taken approximately 1 cm to 2
cm apart until the caudal border of the kidney is reached. The telescope is moved to the first portal after approximately
half the space has been closed (Photo 5). Once the caudal border of the kidney or the nephrosplenic ligament has been reached,
two more suture bites are taken but now in a rostral direction. The author prefers to tie the suture line using an extracorporeal
knot, but an intracorporeal knot can be used.
Photo 5: The space is partially closed at this stage of surgery.