Diverticula of the Small Intestine Caused by Vitelline

Diverticula of the Small Intestine Caused by Vitelline Abnormalities; A comparison of 4 Cases H. K. Barnes, L. R. Martinez, P. G. Kelly. Equine Division, Department of Veterinary Clinical Sciences and Animal Husbandry, University of Liverpool, Leahurst, Neston, Wirral CH 64 7 TE, UK. Tel: (+44) 0151 794 6041 Fax: (+44) 0151 794 6034. Background • Distal jejunal diverticula are uncommon but recognised developmental abnormalities in horses, but well-recognised as a cause of intestinal obstruction in humans (Sun et al. , 2012). • Diverticula can be congenital or acquired and can occur along almost any part of the gastrointestinal tract (Simstein 1986). • True embryological diverticula as described generally occur at the antimesenteric border with acquired diverticula frequently occurring at the mesenteric border (Srisajjakul et al. , 2016). • Acquired diverticulae occur secondary to muscular hypertrophy or mucosal rupture and this is evident during histological examination (Navas de Solis et al. , 2015). Objectives • To present cases of distal jejunal diverticula admitted over a six month period for acute abdominal discomfort. Results • Four horses met the inclusion criteria. The mean age was 2. 25 years (range: 1 -4 years). Two horses were mares, two were geldings. • Key findings on arrival included tachycardia in all cases, elevated packed cell volume in 2/4, along with hyperlactatemia (see Table 1). • Multiple loops of distended small intestine were identified on rectal examination. No net reflux was obtained in any case. • All horses displayed moderate to severe discomfort unresponsive to analgesia and underwent exploratory laparotomy. • Cases 1 and 2 had similar mesenteric diverticula at the distal jejunum oral to a mesodiverticular band • Presumed chronic low grade constriction leading to acquired diverticula • No apparent lumincal constriction or muscular hypertrophy to support and acquired aetiology. Case details and outcome Table 1: Results of clinical examination and intraoperative findings Clinical parameters HR (beats per minute) RR (breaths per minute) Gastro-intestinal sounds Mucous membranes Capillary refill (seconds) Rectal temperature (°C) Rectal findings Ultrasonography findings PCV (%) TP (g/l)) Systemic Lactate (mmol/l) Abdominocentesis Nasogastric intubation Intra op findings Case 1 64 Case 2 52 Case 3 80 Case 4 60 24 36 36 Not taken. Absent Pink and moist Mildly congested Hyperaemic and tacky Not recorded >3 <2 3 Not recorded 36. 7 38. 5 39. 0 Not taken. Multiple loops distended small intestine (DSI) Multiple loops DSI (up to 5. 5 cm)and increased mural thickness (4 mm) 37 70 low Multiple loops DSI (up to 6 cm) Multiple loops DSI 54 66 low Multiple loops DSI with thickened wall and severe peritoneal effusion. 50 80 11. 5 Pale yellow and clear with TP 22 g/l and lactate 2. 3 mm/l No net reflux. Not performed Serosanguinous Not performed No net reflux Not performed Mesenteric diverticulum oral to mesodiverticular band. Segmental volvulus of jejunum 240 cm Jejunojejunal PTS at 24 hours – developed post operative ileus and client elected not to continue Meckels diverticulum Mesoodiverticular resulting in strangulation of band strangulating a segment of jejunum distal jejunum and ileum N/A 205 cm N/A Jejunocaecal PTS during surgery – Client PTS at 10 days – repeat decision colic. Necrotic ileal stump Mesenteric diverticulum oral to mesodiverticular band. Simple impaction of diverticulum Length of resection 80 cm Anastomosis Jejunojejunal Outcome Discharged at 8 days 36 58 2. 2 • Survival to discharge from the hospital was 25%. • All cases required small intestinal resection with two jejuno-jejunostomies (cases 1 and 2) and one jejunocaecostomy (case 4). • Repeat laparotomy was performed in case 4 at 10 days post-surgery due to repeat colic and the horse was euthanised during surgery with a necrotic ileal stump. Discussion Figure 1: Intra-operative image (Case 1) showing large mesenteric diverticulum with thin aboral mesodiverticular band (at left hand). Figure 3: Jejunal segment following resection (Case 2) demonstrating the mesodiverticular band to the left and the mesenteric diverticulum. Figure 5: Mesodiverticular band adhered to omentum with strangulated distal jejunum and ileum (Case 4). The horse has a side to side jejunocaecal anastomoisis performed, however was euthanised at 10 days post op due to necrosis of the ileal stump. Figure 2: The serosal surface following surgical excision of the mesenteric diverticulum in Case 1 (see figure 1). Figure 4: Meckel’s diverticulum associated with stragulation of distal jejunum (Case 3). The client elected not to proceed with treatment. • Congenital diverticula frequently form from vitelline remnant abnormalities (Riccaboni et al. , 2000), • Mesodiverticular bands develop from a persistent omphalomesenteric artery and Meckel’s Diverticulum from the omphalomesenteric duct (Southwood, 2008). • Two diverticula (cases 1 and 2) were present on the mesenteric border. A similar lesion is previously described (Wefel et al. , 2011); however in contrast to that report there was no strangulation or incarceration associated with the mesodiverticular band (Abutarbush et al. , 2003). • This is also in contrast to case 4 which represents a more commonly reported presentation with incarceration of jejunum and or ileum into the diverticulum • The true aetiology of the first two lesions requires further investigation • This series highlights the different configurations of distal jejunal diverticula and highlights the potential sequalae that can develop as a result of a previously asymptomatic abnormality. Conclusions • Vitelline abnormalities, while uncommon, should be considered as a differential for acute abdominal pain in horses less than 4 years of age. • Further investigation is required to classify and define the pathogenesis of some lesions References • Abutarbush, S. M. , Shoemaker, R. W. & Bailey, J. V. , 2003. Strangulation of the small intestines by a mesodiverticular band in 3 adult horses. Canadian Veterinary journal, Volume 44, pp. 1005 -1006. • Navas de Solis, C. et al. , 2015. Imaging diagnosis- muscular hypertrophy of the small intestine and pseudodiverticula in a horse. Veterinary radiology and ultrasound, Volume 56, pp. 13 -16. • Riccaboni, P. , Tassan, S. & Mayer, P. , 2000. Rare intestinal malformaiton (diverticulum confluens) in a horse. Equine Veterinary Journal, 32(4), pp. 351 -353. • Simstein, N. L. , 1986. Congenital gastric abnormalities. The American Journal of Surgery, Volume 52, pp. 264 -268. • Southwood, L. L. , 2008. Gastrointestinal tract diverticula: What, when and why? . Equine Veterinary Education, 20(11), pp. 572 -574. • Srisajjakul, S. , Prapaisilp , P. & Bangchokdee, S. , 2016. Many faces of Meckel’s diverticulum and its complications. Japan Journal of Radiology, Volume 34, pp. 313 -320. • Sun, C. , Hu, X. & Huang, L. , 2012. Intestinal obstruction due to congenital bands from vitelline remnants. Journal of ultrasound medicine, Volume 31, pp. 2035 -2038. • Wefel, S. , Mendez-Angulo, J. L. & Ernst, N. S. , 2011. Small intestinal strangulation caused by a mesodiverticular band diverticulum on the mesenteric border of the small intestin in a horse. Canadian Veterinary Journal, Volume 52, pp. 884 -887.