Abdominal pain and weight loss due to compression of the superior mesenteric vein

I describe below a previously unknown compression syndrome characterized by post-prandially unbearable abdominal pain, post-prandial distension of the abdomen mainly in the right upper abdomen, weight loss to cachexia due to an inability to eat sufficiently as a consequence of a venous congestion of the small intestine due to a compression of the superior mesenteric vein and splenic vein at their confluence by the hepatic artery.

The four patients presented here, three women aged 41 (A),  25 (B), 22 (D), a young man (15 years), suffered from hypermobility syndrome with significantly hypermobile joints and widened (A,B) or hypertrophic (C) scars.

The patients experienced the following main symptoms, which significantly overlapped:

Patient A experienced a weight loss of 12 kg within 12 months. Feeling full after eating for about 15 minutes, followed by bloating and loud, stormy bowel movements audible externally. Bloody stools despite an unremarkable colonoscopy. Recurrent diarrhea, change in bowel habits from constipation to diarrhea. Slow intestinal transport caused severe pain in the right flank. Due to pain and nausea, the patient was unable to eat and was on the brink of parenteral nutrition with a BMI of 14. The patient also experienced recurrent thrombosis of the anal canal, gastroparesis, incomplete paraparesis, and numbness of the anus and rectal canal.

Patient B has experienced frequent abdominal pain since early childhood, with increasing intensity. Requires total parenteral nutrition and percutaneous gastrostomy. Experiences unbearable pain when using the gastrostomy. Has postprandial pain localized in the right hypochondrium. Has lost 30 kg in the last six months. Severe nausea and frequent vomiting with no appetite or hunger; extreme constipation; burping; early satiety; intestinal bleeding; bloating; dizziness; tachycardia; shortness of breath; and episodes of dyspnea. She must use a wheelchair due to instability in her knee joints.

Patient C has suffered from chronic, postprandial abdominal pain since very early childhood. He started preferring mashed food at an early school age. He developed increasing weakness due to malnourishment from his inability to consume sufficient food. The patient experiences postprandial pain in the upper midline abdomen at a level of 8/10, starting three minutes after the first bite. He suffers from chronic headaches and vertigo that worsen when he stands or sits. He is unable to stand for a few minutes and requires parenteral nutrition for 60% of his daily calories.

Patient D suffered from unbearable post-prandial pain in the right hypochondrium, daily diarrhoea, inability to take up sufficient amount of food, headaches, menstrual pain

Sonographic signs of small bowel dysfunction were found, including significant meteorism, disturbed peristalsis, distension of the descending portion of the duodenum, retroperistalsis, immediate gas formation in the duodenum after food contact, a feeling of disturbed food transport without evidence of duodenal compression, and severe constipation.

Despite active gastric contractions, the duodenal dysfunction was impressive in Patient C. This resulted in cessation of intestinal transport in the descending portion of the duodenum.

The patients suffered from other abdominal vascular compression syndromes:

Compression syndromes are caused by the narrowing of the abdominal cavity due to increased lumbar lordosis and a flat thorax with reduced sagittal width at the upper and lower aperture.

One way to measure this is by determining the minimum distance between the inner lining of the abdominal wall and the highest apex of the lordotic curvature. Regarding the development of gastrointestinal symptoms, it is important to note that the small intestines, which lie ventral to the spine and compete with the patient’s soft veins for space in the midline of the abdominal cavity, require a minimum space of 20-25 mm during peristalsis. This explains why these patients experience cramping pain in the mid and lower abdomen, which radiates towards the pelvis, about 30 minutes after beginning a meal. Assuming normal peristaltic activity, this is the time when food arrives in the lower abdomen. Then, the filled jejunum and ileum enlarge to a transverse diameter of 20-25 mm, which is obviously greater than the minimum distance found in the four patients presented here. The measurements were taken while the patients were lying supine, and they would probably decrease further while standing due to increased lumbar lordosis.

Postural tachycardia due to a massive volume shift toward the lower body occurred in all patients, causing an inability to stand and signs of postural tachycardia syndrome. Quantitative color Doppler sonography was used to evaluate the extent of this venous pooling, which was observed as a reduction in left ventricular filling while standing compared to a horizontal posture.

A normal orthostatic perfusion drop is less than 8%. For affected patients, however, it ranged between 22 and 66%.

This caused severe cerebral and circulatory symptoms when upright, whether sitting or standing. Patients could not sit or stand for even a few minutes without becoming dizzy or nearly fainting. Patient C was so severely affected that he lost his ability to remember, so he could not write simple texts. He was constantly on the verge of losing consciousness and had to lie down constantly. Impressively, after decompressing the left renal vein and the left common iliac vein, he could walk up to 10 km a day, although he still could not stand for long periods of time, despite reducing his left ventricular filling loss to 30%. However, he could memorize again, sit upright for longer periods, and interact with his family members.

However, all four patients suffered from congestion of the small intestines due to compression of the mesenteric vein at its unification with the splenic vein. We could quantify this in Patient C with four-dimensional PixelFlux measurements of the superior mesenteric vein’s venous flow volume before and after a meal.

For patient A, one-finger palpation of the most painful area corresponded exactly to the sonographically localized compression site of the mesenteric vein.

In patient B, compression of the mesenteric vein increased postprandially due to additional squeezing of the vein between the enlarging duodenum and the lesser curvature of the stomach.

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For patient C, compression was most pronounced when lying horizontally or sitting slouched. Sitting with a straight back significantly reduced compression.

Orthostatic nephroptosis was determined sonographically by measuring the distance between the upper or lower pole of the kidney and the ipsilateral iliac crest.

Two of the three patients had nephroptosis of the right kidney, which could be explained by simultaneous hepatoptosis.

Thus, it is worthwhile to search for compression of the mesenteric and splenic veins in cachectic patients (BMI <20) with severe, postprandial abdominal pain localized in the right upper quadrant, diarrhea, and the need for parenteral nutrition due to an inability to be sufficiently nourished by the oral route.